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Re: Looking for a XYZ ARINC407 syncho explanation in simple terms
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jla...@highlandsniptechnology.com
Feb 8, 2021, 1:03:13 PM2/8/21
to
On Mon, 08 Feb 2021 17:06:03 +0000, Peter <nos...@nospam9876.com>
wrote:
>I have read a lot about this subject and can see how it works. Most of
>the material is 50+ years old and it is really mostly quite simple.
>
>But I need some specific advice for something I am building.
>
>It is a box which takes in serial data containing an angle, 0 to -180
>(for western headings) or 0 to +180 (for eastern headings).
>
>Yes, south can be both -180 or +180 but that's not a problem :)
>
>I am using two DACs to generate the two output sinewaves, 400Hz. These
>are called X and Y.
>
>I could optionally also generate the reference one, possibly called Z
>I think, also 400Hz but for reasons unrelated a lot more power
>capability is needed.
>
>What I can't get my head around is how to arrange the phases.
>
>I *think* the reference would be an INPUT to this box, and the angle
>is represented using the two other sinewaves, which I will be
>generating. The phase will be relative to the reference, somehow.
>
>I can't work out whether X and Y carry the heading between themselves
>or whether they are shifted symmetrically around the reference, or
>whatever.
>
>The signals will go to various instruments used in aviation, for
>testing.
>
>Many thanks in advance for any info. I am sure the answer is very
>simple!
Is this a 2-phase system? Synchros are 3 phases.
"Phases" here doesn't mean continuous phase shifts in a synchro-like
system, it means multiplication of the reference in the range -1,1.
Something like this might be it. I'm not sure of your application.
https://www.dropbox.com/s/b871rgh34ddfej6/Synchro-2p.jpg?raw=1
We do that sort of thing in our synchro simulators, with ADCs and DACs
and DSP and transformer coupling. We've done similar things with
analog multipliers, at higher frequencies, like for oil debris sensor
simulation.
This was fun, used when developing a digital synchroscope.
https://www.dropbox.com/s/7ooglw8uihylmb7/Synchro_Template.JPG?raw=1
--
John Larkin Highland Technology, Inc
The best designs are necessarily accidental.
wrote:
>I have read a lot about this subject and can see how it works. Most of
>the material is 50+ years old and it is really mostly quite simple.
>
>But I need some specific advice for something I am building.
>
>It is a box which takes in serial data containing an angle, 0 to -180
>(for western headings) or 0 to +180 (for eastern headings).
>
>Yes, south can be both -180 or +180 but that's not a problem :)
>
>I am using two DACs to generate the two output sinewaves, 400Hz. These
>are called X and Y.
>
>I could optionally also generate the reference one, possibly called Z
>I think, also 400Hz but for reasons unrelated a lot more power
>capability is needed.
>
>What I can't get my head around is how to arrange the phases.
>
>I *think* the reference would be an INPUT to this box, and the angle
>is represented using the two other sinewaves, which I will be
>generating. The phase will be relative to the reference, somehow.
>
>I can't work out whether X and Y carry the heading between themselves
>or whether they are shifted symmetrically around the reference, or
>whatever.
>
>The signals will go to various instruments used in aviation, for
>testing.
>
>Many thanks in advance for any info. I am sure the answer is very
>simple!
Is this a 2-phase system? Synchros are 3 phases.
"Phases" here doesn't mean continuous phase shifts in a synchro-like
system, it means multiplication of the reference in the range -1,1.
Something like this might be it. I'm not sure of your application.
https://www.dropbox.com/s/b871rgh34ddfej6/Synchro-2p.jpg?raw=1
We do that sort of thing in our synchro simulators, with ADCs and DACs
and DSP and transformer coupling. We've done similar things with
analog multipliers, at higher frequencies, like for oil debris sensor
simulation.
This was fun, used when developing a digital synchroscope.
https://www.dropbox.com/s/7ooglw8uihylmb7/Synchro_Template.JPG?raw=1
--
John Larkin Highland Technology, Inc
The best designs are necessarily accidental.
John Larkin
Feb 8, 2021, 2:34:37 PM2/8/21
to
On Mon, 08 Feb 2021 18:52:41 +0000, Peter <nos...@nospam9876.com>
wrote:
>
>jla...@highlandsniptechnology.com wrote
>example on page 68 here
>http://www.mikeg.net/hobbies/aviation/avionics/installation/Shadin%20ADC-200%20Install.pdf
>you can see the reference coming in on H (Z,C being the GND for that)
>and the two sinewaves on X and Y.
>
>
>However your diagram suggests that all three sinewaves are always in
>phase and it is only the amplitude of X and Y that varies.
That's how a synchro or a resolver or an LVDT works. The information
is in the ratio of in-phase voltages. The 400 Hz excitation available
on an airplane can be really ugly, "wild power", but shaft angles can
still be accurately extracted from the voltage ratios. There are some
clever tracking algorithms.
>
>A multiplying DAC would be a good solution but (a) needs the reference
>to be a good sinewave and (b) the DACs I have, inside an ARM CPU, have
>a limited Vref range.
You probably need bipolar multiplication, too, in the range -1 to 1.
>
>So, if my theory is right about using the reference *phase* and
>generating the two X and Y outputs relative to that, I would just use
>the reference zero crossings for the timing and then generate two
>sinewaves of the appropriate phase and amplitude.
You could do that if the excitation frequency were constant. It's more
normal to multiply the excitation waveform, analog or digitally.
PWM multipliers might be fun.
wrote:
>
>jla...@highlandsniptechnology.com wrote
>
>>Is this a 2-phase system? Synchros are 3 phases.
>>
>>"Phases" here doesn't mean continuous phase shifts in a synchro-like
>>system, it means multiplication of the reference in the range -1,1.
>>
>>Something like this might be it. I'm not sure of your application.
>>
>>https://www.dropbox.com/s/b871rgh34ddfej6/Synchro-2p.jpg?raw=1
>
>I think that is probably it. It is widely used in avionics. For
>>Is this a 2-phase system? Synchros are 3 phases.
>>
>>"Phases" here doesn't mean continuous phase shifts in a synchro-like
>>system, it means multiplication of the reference in the range -1,1.
>>
>>Something like this might be it. I'm not sure of your application.
>>
>>https://www.dropbox.com/s/b871rgh34ddfej6/Synchro-2p.jpg?raw=1
>
>example on page 68 here
>http://www.mikeg.net/hobbies/aviation/avionics/installation/Shadin%20ADC-200%20Install.pdf
>you can see the reference coming in on H (Z,C being the GND for that)
>and the two sinewaves on X and Y.
>
>
>However your diagram suggests that all three sinewaves are always in
>phase and it is only the amplitude of X and Y that varies.
That's how a synchro or a resolver or an LVDT works. The information
is in the ratio of in-phase voltages. The 400 Hz excitation available
on an airplane can be really ugly, "wild power", but shaft angles can
still be accurately extracted from the voltage ratios. There are some
clever tracking algorithms.
>
>A multiplying DAC would be a good solution but (a) needs the reference
>to be a good sinewave and (b) the DACs I have, inside an ARM CPU, have
>a limited Vref range.
You probably need bipolar multiplication, too, in the range -1 to 1.
>
>So, if my theory is right about using the reference *phase* and
>generating the two X and Y outputs relative to that, I would just use
>the reference zero crossings for the timing and then generate two
>sinewaves of the appropriate phase and amplitude.
You could do that if the excitation frequency were constant. It's more
normal to multiply the excitation waveform, analog or digitally.
PWM multipliers might be fun.
John Larkin
Feb 8, 2021, 2:59:30 PM2/8/21
to
On Mon, 08 Feb 2021 19:40:56 +0000, Peter <nos...@nospam9876.com>
wrote:
>
>John Larkin <jlarkin@highland_atwork_technology.com> wrote
>around. An LVDT obviously cannot change the phase of anything.
>
>I wonder how the system manages to output 180 degrees accurately.
>excitation?
>the KFC225 autopilot.
>
>Referring to your diagram, how is the input angle to be encoded into
>the two multiplication ratios?
It's not. Just scale the input sine wave to the outputs.
For a synchro, there are three paths, A B and C. A resolver has two, X
and Y. An LVDT or RVDT could have one or two.
wrote:
>
>John Larkin <jlarkin@highland_atwork_technology.com> wrote
>
>>>However your diagram suggests that all three sinewaves are always in
>>>phase and it is only the amplitude of X and Y that varies.
>>
>>That's how a synchro or a resolver or an LVDT works.
>
>OK; I get it. I didn't realise this is an LVDT, but one which is bent
>>>However your diagram suggests that all three sinewaves are always in
>>>phase and it is only the amplitude of X and Y that varies.
>>
>>That's how a synchro or a resolver or an LVDT works.
>
>around. An LVDT obviously cannot change the phase of anything.
>
>I wonder how the system manages to output 180 degrees accurately.
>
>>The information
>>is in the ratio of in-phase voltages. The 400 Hz excitation available
>>on an airplane can be really ugly, "wild power", but shaft angles can
>>still be accurately extracted from the voltage ratios. There are some
>>clever tracking algorithms.
>
>Do you mean phase-locking an internal reference sinewave to the
>>The information
>>is in the ratio of in-phase voltages. The 400 Hz excitation available
>>on an airplane can be really ugly, "wild power", but shaft angles can
>>still be accurately extracted from the voltage ratios. There are some
>>clever tracking algorithms.
>
>excitation?
>
>>>A multiplying DAC would be a good solution but (a) needs the reference
>>>to be a good sinewave and (b) the DACs I have, inside an ARM CPU, have
>>>a limited Vref range.
>>
>>You probably need bipolar multiplication, too, in the range -1 to 1.
>
>Sure.
>>>A multiplying DAC would be a good solution but (a) needs the reference
>>>to be a good sinewave and (b) the DACs I have, inside an ARM CPU, have
>>>a limited Vref range.
>>
>>You probably need bipolar multiplication, too, in the range -1 to 1.
>
>
>>>So, if my theory is right about using the reference *phase* and
>>>generating the two X and Y outputs relative to that, I would just use
>>>the reference zero crossings for the timing and then generate two
>>>sinewaves of the appropriate phase and amplitude.
>>
>>You could do that if the excitation frequency were constant. It's more
>>normal to multiply the excitation waveform, analog or digitally.
>
>That's a very good point. And I know of systems which are ~500Hz e.g.
>>>So, if my theory is right about using the reference *phase* and
>>>generating the two X and Y outputs relative to that, I would just use
>>>the reference zero crossings for the timing and then generate two
>>>sinewaves of the appropriate phase and amplitude.
>>
>>You could do that if the excitation frequency were constant. It's more
>>normal to multiply the excitation waveform, analog or digitally.
>
>the KFC225 autopilot.
>
>>PWM multipliers might be fun.
>
>That's one way to do multiplication.
>>PWM multipliers might be fun.
>
>
>Referring to your diagram, how is the input angle to be encoded into
>the two multiplication ratios?
It's not. Just scale the input sine wave to the outputs.
For a synchro, there are three paths, A B and C. A resolver has two, X
and Y. An LVDT or RVDT could have one or two.
John Larkin
Feb 8, 2021, 3:37:59 PM2/8/21
to
On Mon, 08 Feb 2021 20:05:02 +0000, Peter <nos...@nospam9876.com>
>
>I have an input parameter, a decimal value from -180 to +180, coming
>via RS232.
>
>I have the reference waveform, nominally 400Hz. This is supposed to be
>sine but is often pretty square.
>
>I need to generate the two outputs X and Y.
Suppose you want to simulate 45 degrees. Multiply the reference
sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
call that Y.
If some time later you want to change the simulated angle, change the
two multipliers. The Y factor is cos(angle) and the x factor is sin.
>>>Referring to your diagram, how is the input angle to be encoded into
>>>the two multiplication ratios?
>>
>>It's not. Just scale the input sine wave to the outputs.
>>
>>For a synchro, there are three paths, A B and C. A resolver has two, X
>>and Y. An LVDT or RVDT could have one or two.
>
>You've lost me there :)
>>>the two multiplication ratios?
>>
>>It's not. Just scale the input sine wave to the outputs.
>>
>>For a synchro, there are three paths, A B and C. A resolver has two, X
>>and Y. An LVDT or RVDT could have one or two.
>
>
>I have an input parameter, a decimal value from -180 to +180, coming
>via RS232.
>
>I have the reference waveform, nominally 400Hz. This is supposed to be
>sine but is often pretty square.
>
>I need to generate the two outputs X and Y.
Suppose you want to simulate 45 degrees. Multiply the reference
sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
call that Y.
If some time later you want to change the simulated angle, change the
two multipliers. The Y factor is cos(angle) and the x factor is sin.
Bill Sloman
Feb 8, 2021, 8:26:25 PM2/8/21
to
On Tuesday, February 9, 2021 at 7:37:59 AM UTC+11, John Larkin wrote:
> On Mon, 08 Feb 2021 20:05:02 +0000, Peter <nos...@nospam9876.com>
> wrote:
>
> >
> >John Larkin <jlarkin@highland_atwork_technology.com> wrote
> >
> >>>Referring to your diagram, how is the input angle to be encoded into
> >>>the two multiplication ratios?
> >>
> >>It's not. Just scale the input sine wave to the outputs.
> >>
> >>For a synchro, there are three paths, A B and C. A resolver has two, X
> >>and Y. An LVDT or RVDT could have one or two.
> >
> >You've lost me there :)
> >
> >I have an input parameter, a decimal value from -180 to +180, coming
> >via RS232.
> >
> >I have the reference waveform, nominally 400Hz. This is supposed to be
> >sine but is often pretty square.
> >
> >I need to generate the two outputs X and Y.
>
> Suppose you want to simulate 45 degrees. Multiply the reference
> sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
> call that Y.
If you want to simulate 45 degrees you need to add equal parts of an in-phase sine wave and a quadrature sine wave (which is to say a cosine wave) and scale the sum back by 0.707 (which will leave you with the same peak amplitude as the sine and cosine waves - though it won't peak at the same time as either of them peaks.
> On Mon, 08 Feb 2021 20:05:02 +0000, Peter <nos...@nospam9876.com>
> wrote:
>
> >
> >John Larkin <jlarkin@highland_atwork_technology.com> wrote
> >
> >>>Referring to your diagram, how is the input angle to be encoded into
> >>>the two multiplication ratios?
> >>
> >>It's not. Just scale the input sine wave to the outputs.
> >>
> >>For a synchro, there are three paths, A B and C. A resolver has two, X
> >>and Y. An LVDT or RVDT could have one or two.
> >
> >You've lost me there :)
> >
> >I have an input parameter, a decimal value from -180 to +180, coming
> >via RS232.
> >
> >I have the reference waveform, nominally 400Hz. This is supposed to be
> >sine but is often pretty square.
> >
> >I need to generate the two outputs X and Y.
>
> Suppose you want to simulate 45 degrees. Multiply the reference
> sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
> call that Y.
John Larkin's exposition seems to have left out the phase shifts.
> If some time later you want to change the simulated angle, change the
> two multipliers. The Y factor is cos(angle) and the x factor is sin.
--
Bill Sloman, Sydney
jla...@highlandsniptechnology.com
Feb 9, 2021, 10:16:08 AM2/9/21
to
On Tue, 09 Feb 2021 07:02:44 +0000, Peter <nos...@nospam9876.com>
wrote:
>
>Bill Sloman <bill....@ieee.org> wrote
Sloman is confusing synchronous motor with synchro. The only
deliberate phase shift from the reference in a
synchro/resolver/CT/LVDT/RVDT system is 0 or 180.
There are no intentional phase shifters inside a synchro or resolver.
>
>I wonder how this is done in typical avionics instruments, given the
>reference is usually a crappy waveform. Typically it comes out of a
>crude two transistor oscillator driving a transformer, which enables
>it to be done without +/- supplies. So the XY outputs should be the
>same crappy waveform. And filtering won't do it because you will get a
>massive phase shift. Perhaps the answer is that it just works...
In a real airplane, the 400 Hz can come from all sorts of places:
ground power, one of the main engines, the APU, batteries, or "the
thing you never want to see used", a RAT. So naturally, it's not very
stable on frequency or voltage. There are some special alternators
that make a decent 400 Hz over a range of shaft speeds.
>
>Doing it properly would involve a PLL. That would solve both the
>crappy reference waveform, and the frequency which is only roughly
>400Hz.
Synchros work to arc-seconds precision with junky references. The
angular data is encoded in amplitude ratios. I don't understand your
application, but it sounds like you need two MDACs or equivalent.
>
>One recent avionics product (from Garmin) no longer works with the
>usual reference; they insist on a pure sinewave :)
Tacky. Possibly dangerous.
wrote:
>
>Bill Sloman <bill....@ieee.org> wrote
>
>>> Suppose you want to simulate 45 degrees. Multiply the reference
>>> sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
>>> call that Y.
>>
>>If you want to simulate 45 degrees you need to add equal parts of an in-phase sine wave and a quadrature sine wave (which is to say a cosine wave) and scale the sum back by 0.707 (which will leave you with the same peak amplitude as the sine and cosine waves - though it won't peak at the same time as either of them peaks.
>>
>>John Larkin's exposition seems to have left out the phase shifts.
>>
>>> If some time later you want to change the simulated angle, change the
>>> two multipliers. The Y factor is cos(angle) and the x factor is sin.
>>
>>Not the clearest exposition ever posted.
>>
>>--
>
>OK - super many thanks. I get it!!
>>> Suppose you want to simulate 45 degrees. Multiply the reference
>>> sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
>>> call that Y.
>>
>>If you want to simulate 45 degrees you need to add equal parts of an in-phase sine wave and a quadrature sine wave (which is to say a cosine wave) and scale the sum back by 0.707 (which will leave you with the same peak amplitude as the sine and cosine waves - though it won't peak at the same time as either of them peaks.
>>
>>John Larkin's exposition seems to have left out the phase shifts.
>>
>>> If some time later you want to change the simulated angle, change the
>>> two multipliers. The Y factor is cos(angle) and the x factor is sin.
>>
>>Not the clearest exposition ever posted.
>>
>>--
>
Sloman is confusing synchronous motor with synchro. The only
deliberate phase shift from the reference in a
synchro/resolver/CT/LVDT/RVDT system is 0 or 180.
There are no intentional phase shifters inside a synchro or resolver.
>
>I wonder how this is done in typical avionics instruments, given the
>reference is usually a crappy waveform. Typically it comes out of a
>crude two transistor oscillator driving a transformer, which enables
>it to be done without +/- supplies. So the XY outputs should be the
>same crappy waveform. And filtering won't do it because you will get a
>massive phase shift. Perhaps the answer is that it just works...
In a real airplane, the 400 Hz can come from all sorts of places:
ground power, one of the main engines, the APU, batteries, or "the
thing you never want to see used", a RAT. So naturally, it's not very
stable on frequency or voltage. There are some special alternators
that make a decent 400 Hz over a range of shaft speeds.
>
>Doing it properly would involve a PLL. That would solve both the
>crappy reference waveform, and the frequency which is only roughly
>400Hz.
Synchros work to arc-seconds precision with junky references. The
angular data is encoded in amplitude ratios. I don't understand your
application, but it sounds like you need two MDACs or equivalent.
>
>One recent avionics product (from Garmin) no longer works with the
>usual reference; they insist on a pure sinewave :)
Tacky. Possibly dangerous.
jla...@highlandsniptechnology.com
Feb 9, 2021, 10:51:37 AM2/9/21
to
On Tue, 09 Feb 2021 15:43:59 +0000, Peter <nos...@nospam9876.com>
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>I don't understand your
>>application, but it sounds like you need two MDACs or equivalent.
>
>I am just trying to generate the XYZ signals for testing avionic
>instruments.
Buy one of these!
http://www.highlandtechnology.com/DSS/P545DS.shtml
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>I don't understand your
>>application, but it sounds like you need two MDACs or equivalent.
>
>instruments.
Buy one of these!
http://www.highlandtechnology.com/DSS/P545DS.shtml
jla...@highlandsniptechnology.com
Feb 9, 2021, 11:28:17 AM2/9/21
to
On Tue, 09 Feb 2021 16:22:32 +0000, Peter <nos...@nospam9876.com>
Short attention span.
>
>I need something small, and I will build 5-10 of them. It is a part of
>something else.
Let me know if I can help, design review or something.
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>>I am just trying to generate the XYZ signals for testing avionic
>>>instruments.
>>
>>Buy one of these!
>>
>>http://www.highlandtechnology.com/DSS/P545DS.shtml
>
>You have been very productive in your life! :)
>
> jla...@highlandsniptechnology.com wrote:
>
>>>I am just trying to generate the XYZ signals for testing avionic
>>>instruments.
>>
>>Buy one of these!
>>
>>http://www.highlandtechnology.com/DSS/P545DS.shtml
>
Short attention span.
>
>I need something small, and I will build 5-10 of them. It is a part of
>something else.
Let me know if I can help, design review or something.
DecadentLinux...@decadence.org
Feb 9, 2021, 11:40:04 AM2/9/21
to
jla...@highlandsniptechnology.com wrote in
news:ltd52gpgpr8btgtha...@4ax.com:
> On Tue, 09 Feb 2021 16:22:32 +0000, Peter <nos...@nospam9876.com>
> wrote:
>
>>
>> jla...@highlandsniptechnology.com wrote:
>>
>>>>I am just trying to generate the XYZ signals for testing avionic
>>>>instruments.
>>>
>>>Buy one of these!
>>>
>>>http://www.highlandtechnology.com/DSS/P545DS.shtml
>>
>>You have been very productive in your life! :)
>
> Short attention span.
>
>>
>>I need something small, and I will build 5-10 of them. It is a
>>part of something else.
>
> Let me know if I can help, design review or something.
>
>
>
First off, there is no ARINC 407.
IN the 400 Series, there is 404, 424, and 429. It is all ATR
comms.
There is a 604 for built in test equipment.
407 is only in interface spec. 3 wire.
Study ATR and the 400 series and answers about synching interlinks
will emerge.
news:ltd52gpgpr8btgtha...@4ax.com:
> On Tue, 09 Feb 2021 16:22:32 +0000, Peter <nos...@nospam9876.com>
> wrote:
>
>>
>> jla...@highlandsniptechnology.com wrote:
>>
>>>>I am just trying to generate the XYZ signals for testing avionic
>>>>instruments.
>>>
>>>Buy one of these!
>>>
>>>http://www.highlandtechnology.com/DSS/P545DS.shtml
>>
>>You have been very productive in your life! :)
>
> Short attention span.
>
>>
>>I need something small, and I will build 5-10 of them. It is a
>>part of something else.
>
> Let me know if I can help, design review or something.
>
>
>
IN the 400 Series, there is 404, 424, and 429. It is all ATR
comms.
There is a 604 for built in test equipment.
407 is only in interface spec. 3 wire.
Study ATR and the 400 series and answers about synching interlinks
will emerge.
Tauno Voipio
Feb 9, 2021, 12:48:09 PM2/9/21
to
On 8.2.21 19.06, Peter wrote:
> I have read a lot about this subject and can see how it works. Most of
> the material is 50+ years old and it is really mostly quite simple.
>
> But I need some specific advice for something I am building.
>
> It is a box which takes in serial data containing an angle, 0 to -180
> (for western headings) or 0 to +180 (for eastern headings).
>
> Yes, south can be both -180 or +180 but that's not a problem :)
>
> I am using two DACs to generate the two output sinewaves, 400Hz. These
> are called X and Y.
>
> I could optionally also generate the reference one, possibly called Z
> I think, also 400Hz but for reasons unrelated a lot more power
> capability is needed.
>
> What I can't get my head around is how to arrange the phases.
>
> I *think* the reference would be an INPUT to this box, and the angle
> is represented using the two other sinewaves, which I will be
> generating. The phase will be relative to the reference, somehow.
>
> I can't work out whether X and Y carry the heading between themselves
> or whether they are shifted symmetrically around the reference, or
> whatever.
>
> The signals will go to various instruments used in aviation, for
> testing.
>
> Many thanks in advance for any info. I am sure the answer is very
> simple!
Get the book from <https://www.ddc-web.com/Documents/synhdbk.pdf>,
> I have read a lot about this subject and can see how it works. Most of
> the material is 50+ years old and it is really mostly quite simple.
>
> But I need some specific advice for something I am building.
>
> It is a box which takes in serial data containing an angle, 0 to -180
> (for western headings) or 0 to +180 (for eastern headings).
>
> Yes, south can be both -180 or +180 but that's not a problem :)
>
> I am using two DACs to generate the two output sinewaves, 400Hz. These
> are called X and Y.
>
> I could optionally also generate the reference one, possibly called Z
> I think, also 400Hz but for reasons unrelated a lot more power
> capability is needed.
>
> What I can't get my head around is how to arrange the phases.
>
> I *think* the reference would be an INPUT to this box, and the angle
> is represented using the two other sinewaves, which I will be
> generating. The phase will be relative to the reference, somehow.
>
> I can't work out whether X and Y carry the heading between themselves
> or whether they are shifted symmetrically around the reference, or
> whatever.
>
> The signals will go to various instruments used in aviation, for
> testing.
>
> Many thanks in advance for any info. I am sure the answer is very
> simple!
read it and come back with the remaining questions.
--
-TV
John Larkin
Feb 9, 2021, 4:31:14 PM2/9/21
to
On Tue, 09 Feb 2021 21:18:21 +0000, Peter <nos...@nospam9876.com>
wrote:
>
>Tauno Voipio <tauno....@notused.fi.invalid> wrote
>
>I've just gone through it and struggled to find something which
>directly tells me how this system is implemented.
>
>Maybe some of the maths was applicable but maths is not my strong
>point :)
>
>The diagram posted above by John, with the two multiplying DACs, seems
>very clear.
A resolver transmitter is a shaft with an armature winding. The 400 Hz
excitation powers that coil. The case has two stator windings,
mechanically 90 degrees apart. The AC mag field from the armature
induces AC voltage into the stator windings, voltage ratio ballpark
1:1, minimal phase shift. As the armature changes angular position,
the coupling into the two stator coils changes in the obvious way.
It's just a pair of variable transformers.
A transmitter synchro has three stator windings.
Connect two units, and they can act as if an invisible coupling
connects the two synchro shafts, but they are not generally used that
way.
wrote:
>
>Tauno Voipio <tauno....@notused.fi.invalid> wrote
>
>>
>>Get the book from <https://www.ddc-web.com/Documents/synhdbk.pdf>,
>>read it and come back with the remaining questions.
>
>Thank you.
>>
>>Get the book from <https://www.ddc-web.com/Documents/synhdbk.pdf>,
>>read it and come back with the remaining questions.
>
>
>I've just gone through it and struggled to find something which
>directly tells me how this system is implemented.
>
>Maybe some of the maths was applicable but maths is not my strong
>point :)
>
>The diagram posted above by John, with the two multiplying DACs, seems
>very clear.
A resolver transmitter is a shaft with an armature winding. The 400 Hz
excitation powers that coil. The case has two stator windings,
mechanically 90 degrees apart. The AC mag field from the armature
induces AC voltage into the stator windings, voltage ratio ballpark
1:1, minimal phase shift. As the armature changes angular position,
the coupling into the two stator coils changes in the obvious way.
It's just a pair of variable transformers.
A transmitter synchro has three stator windings.
Connect two units, and they can act as if an invisible coupling
connects the two synchro shafts, but they are not generally used that
way.
Phil Hobbs
Feb 9, 2021, 5:26:50 PM2/9/21
to
mainly in antenna rotators.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
John Larkin
Feb 9, 2021, 5:49:54 PM2/9/21
to
loop, with a motor doing the heavy lifting. A bare synchro receiver
can move small stuff, like a needle in an instrument display.
A lot of military gear used synchros to do math, like targeting
torpedoes, before computers. They are still a common position sensor
in aircraft. A throttle lever is usually an RVDT these days, similar
to a synchro transmitter.
Phil Hobbs
Feb 9, 2021, 6:17:25 PM2/9/21
to
though. Or maybe the receiver ran a big mag amp gizmo that controlled
the motor?
>
> A lot of military gear used synchros to do math, like targeting
> torpedoes, before computers. They are still a common position sensor
> in aircraft. A throttle lever is usually an RVDT these days, similar
> to a synchro transmitter.
stage motion controllers, and they work great--competitive with
calibrated glass linear scales, but with far less sensitivity to
cross-axis motion.
John Larkin
Feb 9, 2021, 7:36:46 PM2/9/21
to
On Tue, 9 Feb 2021 18:17:08 -0500, Phil Hobbs
There were all sorts of things, like amplidynes (getting gain out of a
generator by inputting into the field).
One of the RadLab books is "Servomechanisms"
>
>>
>> A lot of military gear used synchros to do math, like targeting
>> torpedoes, before computers. They are still a common position sensor
>> in aircraft. A throttle lever is usually an RVDT these days, similar
>> to a synchro transmitter.
>
>LVDTs and RVDTs are a really good technology. I've used LVDTs in scan
>stage motion controllers, and they work great--competitive with
>calibrated glass linear scales, but with far less sensitivity to
>cross-axis motion.
LVDTs can have nm resolution. But they are not very linear or
repeatable between units.
generator by inputting into the field).
One of the RadLab books is "Servomechanisms"
>
>>
>> A lot of military gear used synchros to do math, like targeting
>> torpedoes, before computers. They are still a common position sensor
>> in aircraft. A throttle lever is usually an RVDT these days, similar
>> to a synchro transmitter.
>
>LVDTs and RVDTs are a really good technology. I've used LVDTs in scan
>stage motion controllers, and they work great--competitive with
>calibrated glass linear scales, but with far less sensitivity to
>cross-axis motion.
repeatable between units.
Bill Sloman
Feb 9, 2021, 8:37:25 PM2/9/21
to
On Wednesday, February 10, 2021 at 2:16:08 AM UTC+11, jla...@highlandsniptechnology.com wrote:
> On Tue, 09 Feb 2021 07:02:44 +0000, Peter <nos...@nospam9876.com>
> wrote:
>
> >
> >Bill Sloman <bill....@ieee.org> wrote
> >
> >>> Suppose you want to simulate 45 degrees. Multiply the reference
> >>> sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
> >>> call that Y.
> >>
> >>If you want to simulate 45 degrees you need to add equal parts of an in-phase sine wave and a quadrature sine wave (which is to say a cosine wave) and scale the sum back by 0.707 (which will leave you with the same peak amplitude as the sine and cosine waves - though it won't peak at the same time as either of them peaks.
> >>
> >>John Larkin's exposition seems to have left out the phase shifts.
> >>
> >>> If some time later you want to change the simulated angle, change the
> >>> two multipliers. The Y factor is cos(angle) and the x factor is sin.
> >>
> >>Not the clearest exposition ever posted.
> >
> On Tue, 09 Feb 2021 07:02:44 +0000, Peter <nos...@nospam9876.com>
> wrote:
>
> >
> >Bill Sloman <bill....@ieee.org> wrote
> >
> >>> Suppose you want to simulate 45 degrees. Multiply the reference
> >>> sine-ish wave by 0.707 and call that X. Multiply it again by 0.707 and
> >>> call that Y.
> >>
> >>If you want to simulate 45 degrees you need to add equal parts of an in-phase sine wave and a quadrature sine wave (which is to say a cosine wave) and scale the sum back by 0.707 (which will leave you with the same peak amplitude as the sine and cosine waves - though it won't peak at the same time as either of them peaks.
> >>
> >>John Larkin's exposition seems to have left out the phase shifts.
> >>
> >>> If some time later you want to change the simulated angle, change the
> >>> two multipliers. The Y factor is cos(angle) and the x factor is sin.
> >>
> >>Not the clearest exposition ever posted.
> >
> >OK - super many thanks. I get it!!
>
> Sloman is confusing synchronous motor with synchro. The only
> deliberate phase shift from the reference in a
> synchro/resolver/CT/LVDT/RVDT system is 0 or 180.
True. I screwed up. Linear variable transformers and rotary variable transformers both work by multiplying the drive waveform by number between +1 and -1.
>
> Sloman is confusing synchronous motor with synchro. The only
> deliberate phase shift from the reference in a
> synchro/resolver/CT/LVDT/RVDT system is 0 or 180.
Since they are transformers the output lags the drive - the one time I had to worry about it is was by about a degree.
It is a simple-minded system, because it dates back to a time when electronics had to be kept simple.
--
Bill Sloman, Sydney
Bill Sloman
Feb 9, 2021, 8:49:24 PM2/9/21
to
They should be better than Moire gratings - everything is averaged over the whole assembly - even if they can't be as good as an interferometer driven from a genuinely monochromatic source.
--
Bill Sloman, Sydney
Tauno Voipio
Feb 10, 2021, 3:52:26 AM2/10/21
to
On 9.2.21 23.18, Peter wrote:
>
> Tauno Voipio <tauno....@notused.fi.invalid> wrote
>
>>
>
> Tauno Voipio <tauno....@notused.fi.invalid> wrote
>
>>
>> Get the book from <https://www.ddc-web.com/Documents/synhdbk.pdf>,
>> read it and come back with the remaining questions.
>
>> read it and come back with the remaining questions.
>
> Thank you.
>
> I've just gone through it and struggled to find something which
> directly tells me how this system is implemented.
>
> Maybe some of the maths was applicable but maths is not my strong
> point :)
>
> The diagram posted above by John, with the two multiplying DACs, seems
> very clear.
For a three-phase synchro system, it is difficult to avoid trigonometry
>
> I've just gone through it and struggled to find something which
> directly tells me how this system is implemented.
>
> Maybe some of the maths was applicable but maths is not my strong
> point :)
>
> The diagram posted above by John, with the two multiplying DACs, seems
> very clear.
(of 30, 60 and 90 degrees, at least).
The two-DAC system usually creates a two-phase system, at 90 degrees
phase shift. It is convertible to three phases using a thing called
the Scott T-transformer. It should be in the book.
For your problem, see section V in the book, from page 49 onward.
--
-TV
Jan Panteltje
Feb 10, 2021, 9:54:58 AM2/10/21
to
On a sunny day (Wed, 10 Feb 2021 13:46:15 +0000) it happened Peter
<nos...@nospam9876.com> wrote in <s00o34$9bq$2...@dont-email.me>:
>
>Bill Sloman <bill....@ieee.org> wrote
>artificial horizon. The LVDT there is "bent" into a circle.
I dunno about all this, sounds like ages old stuff
I have pitch-roll for a boat here, can display it anyway you like by changing the software...
http://panteltje.com/pub/pitch_roll.gif
roll -0° pitch -4 ° bottom screen
is just a MEMS chip:
https://invensense.tdk.com/products/motion-tracking/6-axis/mpu-6050/
No cables, board connected to an old raspberry 1 that does all the other stuff you see too.
My Xiaomi smartphone has a compass and a level,
likely a similar or the same chip.
No wonder planes are expensive and heavy ;-)
Save fuel go digital...
<nos...@nospam9876.com> wrote in <s00o34$9bq$2...@dont-email.me>:
>
>Bill Sloman <bill....@ieee.org> wrote
>
>>> LVDTs can have nm resolution. But they are not very linear or
>>> repeatable between units.
>>
>>They can't be spectacularly linear. You've got a moving slug that adjusts the coupling between the diver coil and the receiving
>>coils. They should be pretty repeatable - the coils involved are wound with wire that has a 2% tolerance on its dimensions, but
>>you should be able to get the same numbers of turns on every winding you ship, and the moving slug and coil formers should be
>>equally close-toleranced.
>>They should be better than Moire gratings - everything is averaged over the whole assembly - even if they can't be as good as
>>an interferometer driven from a genuinely monochromatic source.
>
>A "famous" LVDT implementation is the pitch/roll pickoff on a KI256
>>> LVDTs can have nm resolution. But they are not very linear or
>>> repeatable between units.
>>
>>They can't be spectacularly linear. You've got a moving slug that adjusts the coupling between the diver coil and the receiving
>>coils. They should be pretty repeatable - the coils involved are wound with wire that has a 2% tolerance on its dimensions, but
>>you should be able to get the same numbers of turns on every winding you ship, and the moving slug and coil formers should be
>>equally close-toleranced.
>>They should be better than Moire gratings - everything is averaged over the whole assembly - even if they can't be as good as
>>an interferometer driven from a genuinely monochromatic source.
>
>artificial horizon. The LVDT there is "bent" into a circle.
I dunno about all this, sounds like ages old stuff
I have pitch-roll for a boat here, can display it anyway you like by changing the software...
http://panteltje.com/pub/pitch_roll.gif
roll -0° pitch -4 ° bottom screen
is just a MEMS chip:
https://invensense.tdk.com/products/motion-tracking/6-axis/mpu-6050/
No cables, board connected to an old raspberry 1 that does all the other stuff you see too.
My Xiaomi smartphone has a compass and a level,
likely a similar or the same chip.
No wonder planes are expensive and heavy ;-)
Save fuel go digital...
jla...@highlandsniptechnology.com
Feb 10, 2021, 10:47:28 AM2/10/21
to
On Wed, 10 Feb 2021 13:43:35 +0000, Peter <nos...@nospam9876.com>
>not moving coil. So you get a very positive pointer drive, whereas
>moving coil are affected by the smallest stiction etc.
There is probably a tiny bit of 400 Hz vibration in a synchro off
null, and that can break up static friction.
There were some needle-type carburetors (British sliding-piston SU,
Honda rubber diaphragm) that shouldn't have worked but for engine
vibration. Tweaking an SU carb outside a gay bar won me my wife.
I guess there could be some vibration on an airplane too.
>>The receivers are generally used as the error detector in a servo
>>loop, with a motor doing the heavy lifting. A bare synchro receiver
>>can move small stuff, like a needle in an instrument display.
>
>Indeed; the higher quality aircraft instruments are sunchro driven,
>>loop, with a motor doing the heavy lifting. A bare synchro receiver
>>can move small stuff, like a needle in an instrument display.
>
>not moving coil. So you get a very positive pointer drive, whereas
>moving coil are affected by the smallest stiction etc.
There is probably a tiny bit of 400 Hz vibration in a synchro off
null, and that can break up static friction.
There were some needle-type carburetors (British sliding-piston SU,
Honda rubber diaphragm) that shouldn't have worked but for engine
vibration. Tweaking an SU carb outside a gay bar won me my wife.
I guess there could be some vibration on an airplane too.
jla...@highlandsniptechnology.com
Feb 10, 2021, 10:49:49 AM2/10/21
to
jla...@highlandsniptechnology.com
Feb 10, 2021, 11:38:53 AM2/10/21
to
On Wed, 10 Feb 2021 16:10:02 +0000, Peter <nos...@nospam9876.com>
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>Tweaking an SU carb outside a gay bar won me my wife.
>
>hahahahaha
At the bar she told me her MG Midget was running bad. It was idling at
3000 RPM and I always carry a Swiss army knife. Poor girl thought I
was a genius.
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>Tweaking an SU carb outside a gay bar won me my wife.
>
At the bar she told me her MG Midget was running bad. It was idling at
3000 RPM and I always carry a Swiss army knife. Poor girl thought I
was a genius.
jla...@highlandsniptechnology.com
Feb 10, 2021, 11:48:09 AM2/10/21
to
On Wed, 10 Feb 2021 16:12:33 +0000, Peter <nos...@nospam9876.com>
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>>The two-DAC system usually creates a two-phase system, at 90 degrees
>>>phase shift. It is convertible to three phases using a thing called
>>>the Scott T-transformer. It should be in the book.
>>
>>Yes, but quad dacs are cheap.
>
>AFAICT I will only ever need two outputs, XY, and possibly also
>generate the reference output.
>
>I have never seen three phases used to transmit a heading in avionics.
>
>What I have seen done, and probably 3 phases, is the transmission of a
>bearing, from an instrument where you can twiddle a compass card all
>the way round.
>
I work with big jets. They use 3-stator synchros for things like
engine vane and flap positions, running into a FADEC or some other
computer, not directly to an indicator. Maybe because the 3 phases
provide failure indication.
Throttle levers tend to be RVDTs for some reason. Failure detection
can be done on them, too.
On a 2-phase resolver, four angular positions can lose a signal and
still look correct.
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>>The two-DAC system usually creates a two-phase system, at 90 degrees
>>>phase shift. It is convertible to three phases using a thing called
>>>the Scott T-transformer. It should be in the book.
>>
>>Yes, but quad dacs are cheap.
>
>generate the reference output.
>
>I have never seen three phases used to transmit a heading in avionics.
>
>What I have seen done, and probably 3 phases, is the transmission of a
>bearing, from an instrument where you can twiddle a compass card all
>the way round.
>
I work with big jets. They use 3-stator synchros for things like
engine vane and flap positions, running into a FADEC or some other
computer, not directly to an indicator. Maybe because the 3 phases
provide failure indication.
Throttle levers tend to be RVDTs for some reason. Failure detection
can be done on them, too.
On a 2-phase resolver, four angular positions can lose a signal and
still look correct.
Tauno Voipio
Feb 10, 2021, 12:02:58 PM2/10/21
to
needed to overcome the stiction in the basic aircraft pointer
instruments. In a Piper Navajo simulator there are real aircraft
instruments and behind the panel there is a small DC motor with
an excentric weight on the shaft to vibrate the panel to keep the
instruments alive.
A different story is that modern high quality aircraft instrumenta
are currently panel displays without mechanical pointers, see e.g.
Garmin G1000 glass cockpit. The attitude and heading references are
not gyros anymore, but electronic sensors instead.
--
-TV
jla...@highlandsniptechnology.com
Feb 10, 2021, 12:16:46 PM2/10/21
to
sensor can tell where "down" is? Maybe an accelerometer with a very
long time constant?
Tauno Voipio
Feb 10, 2021, 12:37:18 PM2/10/21
to
The raw attitude needs to be integrated over longish time to even
out random changes. In the similar way, there are etiher optical gyros
or micromechanical rotation sensors. The magnetic heading is sensed
with 3D Hall sensors and rotated to the sensed attitude to compensate
for aircraft attitude and magnetic field tilt.
The main reason for integrating the attitude is that the sensed vertical
differs from the real one in turns and sudden pitch changes.
The attitude gyro in conventional instruments is actually integrating
the sensed vertical with a long time constant. The gyro units contain
special valve systems to adjust the position in the long run.
The electronic sensors are currently available in packages of the
size of a cigarette pack (AHRS), but they are not aircraft-certifiable.
In previous instruments, the magnetic heading was sensed with a flux
valve, which is a saturable magnetic core. It gives out a 3 phase
signal which goes to a synchro-based servo adjusting the heading
master gyro. The output of the master gyro steers the main heading
reference system.
--
-TV
DecadentLinux...@decadence.org
Feb 10, 2021, 12:58:34 PM2/10/21
to
Jan Panteltje <pNaOnSt...@yahoo.com> wrote in
news:s00s3q$1s4n$1...@gioia.aioe.org:
> I dunno about all this, sounds like ages old stuff
> I have pitch-roll for a boat here, can display it anyway you like
> by changing the software...
> http://panteltje.com/pub/pitch_roll.gif
> roll -0ø pitch -4 ø bottom screen
>
It would seem to me that there would be a MEMS chip out there that
does it.
Hell, GE uses an IRU (Inertial Reference Unit) for precise motion
transitions in all directions.
I put a couple hundred in mobile satellite transceivers. They are
$50k each and we were charging $100k each. Every C-130 in service now
has a secure, hot, mobile Internet connection back to the Pentagon with
the cost being a small 2 foot tall bump on top of the fuselage at the
center escpape hatch port. A 12" dish sits under that continually
tracking its bird.
news:s00s3q$1s4n$1...@gioia.aioe.org:
> I dunno about all this, sounds like ages old stuff
> I have pitch-roll for a boat here, can display it anyway you like
> by changing the software...
> http://panteltje.com/pub/pitch_roll.gif
>
It would seem to me that there would be a MEMS chip out there that
does it.
Hell, GE uses an IRU (Inertial Reference Unit) for precise motion
transitions in all directions.
I put a couple hundred in mobile satellite transceivers. They are
$50k each and we were charging $100k each. Every C-130 in service now
has a secure, hot, mobile Internet connection back to the Pentagon with
the cost being a small 2 foot tall bump on top of the fuselage at the
center escpape hatch port. A 12" dish sits under that continually
tracking its bird.
DecadentLinux...@decadence.org
Feb 10, 2021, 1:08:23 PM2/10/21
to
jla...@highlandsniptechnology.com wrote in
news:j1582gdo9bobhab93...@4ax.com:
It is called an inertial reference unit. They replaced gyros over a
decade ago. The GE unit is like 7 x 7 x 9 inches cube and has
several miles of fiber optic coils in it, but has a super fine
resolution too. Smaller units like that in your phone uses MEMS and
are far less resolved.
Here's one (another military grade unit):
<https://aerospace.honeywell.com/en/learn/products/sensors/hg4930-
mems-inertial-measurement-unit>
news:j1582gdo9bobhab93...@4ax.com:
decade ago. The GE unit is like 7 x 7 x 9 inches cube and has
several miles of fiber optic coils in it, but has a super fine
resolution too. Smaller units like that in your phone uses MEMS and
are far less resolved.
Here's one (another military grade unit):
<https://aerospace.honeywell.com/en/learn/products/sensors/hg4930-
mems-inertial-measurement-unit>
jla...@highlandsniptechnology.com
Feb 10, 2021, 1:16:06 PM2/10/21
to
On Wed, 10 Feb 2021 19:37:09 +0200, Tauno Voipio
Or slow turns.
I recall pilots manually zeroing the artificial horizon now and then
to correct for gyro drift, when they could clearly see the horizon.
>
>The attitude gyro in conventional instruments is actually integrating
>the sensed vertical with a long time constant. The gyro units contain
>special valve systems to adjust the position in the long run.
>
>The electronic sensors are currently available in packages of the
>size of a cigarette pack (AHRS), but they are not aircraft-certifiable.
>
>In previous instruments, the magnetic heading was sensed with a flux
>valve, which is a saturable magnetic core. It gives out a 3 phase
>signal which goes to a synchro-based servo adjusting the heading
>master gyro. The output of the master gyro steers the main heading
>reference system.
--
I recall pilots manually zeroing the artificial horizon now and then
to correct for gyro drift, when they could clearly see the horizon.
>
>The attitude gyro in conventional instruments is actually integrating
>the sensed vertical with a long time constant. The gyro units contain
>special valve systems to adjust the position in the long run.
>
>The electronic sensors are currently available in packages of the
>size of a cigarette pack (AHRS), but they are not aircraft-certifiable.
>
>In previous instruments, the magnetic heading was sensed with a flux
>valve, which is a saturable magnetic core. It gives out a 3 phase
>signal which goes to a synchro-based servo adjusting the heading
>master gyro. The output of the master gyro steers the main heading
>reference system.
--
Steve Wilson
Feb 10, 2021, 3:14:31 PM2/10/21
to
jla...@highlandsniptechnology.com wrote:
> I recall pilots manually zeroing the artificial horizon now and then
> to correct for gyro drift, when they could clearly see the horizon.
I owned a Piper Malibu, N4360V, for many years. It was a 6-place,
> I recall pilots manually zeroing the artificial horizon now and then
> to correct for gyro drift, when they could clearly see the horizon.
pressurized, air conditioned, full IFR, certified for flight into known
icing, 25,000 foot ceiling, full autopilot, yaw damper, RNAV, LORAN, VOR,
radio altimeter, 16GPH cross-country plane.
http://www.jetphotos.net/viewphoto.php?id=5874208&nseq=0
It was a dream to fly.
I flew it all over the US, from Boisie to San Diego, Rochester to LA, San
Jose to Boca Raton, San Jose to Boulder, CO, and many other places.
In all the years I owned it, I never had to reset the artificial horizon
even once. Any drift would have messed up the autopilot really bad, which
could have been a disaster at midnight in IMC.
A problem with gyros is they can fail without warning. This invariably
leads to a crash if you are flying in the clouds. I duplicated the pilot's
instrument panel for the copilot's seat so I would always have at least one
working horizon.
Planes that required resetting the artificial horizon may have had bad
gyros that could fail soon. This needs to be fixed before the next flight.
--
The best designs are no accident - sw
Jan Panteltje
Feb 11, 2021, 1:51:41 AM2/11/21
to
On a sunny day (Wed, 10 Feb 2021 15:16:43 +0000) it happened Peter
<nos...@nospam9876.com> wrote in <s00tcs$ipj$1...@dont-email.me>:
>
> Jan Panteltje <pNaOnSt...@yahoo.com> wrote:
>
>>>A "famous" LVDT implementation is the pitch/roll pickoff on a KI256
>>>artificial horizon. The LVDT there is "bent" into a circle.
>>
>>I dunno about all this, sounds like ages old stuff
>>I have pitch-roll for a boat here, can display it anyway you like by changing the software...
>> http://panteltje.com/pub/pitch_roll.gif
>>roll -0° pitch -4 ° bottom screen
>>
>>is just a MEMS chip:
>> https://invensense.tdk.com/products/motion-tracking/6-axis/mpu-6050/
>>No cables, board connected to an old raspberry 1 that does all the other stuff you see too.
>>
>>My Xiaomi smartphone has a compass and a level,
>>likely a similar or the same chip.
>>
>>No wonder planes are expensive and heavy ;-)
>>Save fuel go digital...
>
>This is digressing but you can't certify a ten bob "AHRS" chip as a
>primary pitch/roll reference.
>
>For a start you need to sense the gravity vector, for the slow
>background erection, but you also need three yaw gyros; 2 for pitch
>and roll and one for heading.
>
>All this stuff drifts like hell so it needs to be temperature
>stabilised.
I wrote, years ago a small simulation in what was it language? for an an object (say plane) in space
using those 6 axis chips.
I then wanted to know if inertial navigation was possible (so no GPS but just by recording the MEMS output)
After asking in some some group I ran a drift experiment on that chip, using its internal sensor
to stabilize temperature
then ran some drift tests
http://panteltje.com/pub/acceleration_x_40000_seconds.gif
http://panteltje.com/pub/acceleration_y_40000_seconds.gif
http://panteltje.com/pub/acceleration_z_40000_seconds.gif
I also wanted to know if I could detect the moon orbiting from G measurement with that chip:
http://panteltje.com/pub/z_to_21_8_2015_8_35.gif
from that data I concluded what I was seeing was day-night temperature variation in spite of using the chips internal temperature
sensor to keep it at a fixed temperature.
Thinking about that, it seemed to me PCB temperature change does put mechanical stress on the chip, could be an explanation.
Then some uni repeated that experiment with the whole thing in a temp controlled oven.
IMO that was a good move,, usually those projects then go silent as DOD gets interested,
I went on to playing with the next interesting thing.....
But big mechanical giros (V2?) or laser giros (bit later)? or MEMS ?
MEMS may be good enough,
>The mechanical gyros are accepted because they have been around for
>many decades.
So have been camp fires :-)
Personally I use a microwave.
<nos...@nospam9876.com> wrote in <s00tcs$ipj$1...@dont-email.me>:
>
> Jan Panteltje <pNaOnSt...@yahoo.com> wrote:
>
>>>A "famous" LVDT implementation is the pitch/roll pickoff on a KI256
>>>artificial horizon. The LVDT there is "bent" into a circle.
>>
>>I dunno about all this, sounds like ages old stuff
>>I have pitch-roll for a boat here, can display it anyway you like by changing the software...
>> http://panteltje.com/pub/pitch_roll.gif
>>roll -0° pitch -4 ° bottom screen
>>
>>is just a MEMS chip:
>> https://invensense.tdk.com/products/motion-tracking/6-axis/mpu-6050/
>>No cables, board connected to an old raspberry 1 that does all the other stuff you see too.
>>
>>My Xiaomi smartphone has a compass and a level,
>>likely a similar or the same chip.
>>
>>No wonder planes are expensive and heavy ;-)
>>Save fuel go digital...
>
>primary pitch/roll reference.
>
>For a start you need to sense the gravity vector, for the slow
>background erection, but you also need three yaw gyros; 2 for pitch
>and roll and one for heading.
>
>All this stuff drifts like hell so it needs to be temperature
>stabilised.
I wrote, years ago a small simulation in what was it language? for an an object (say plane) in space
using those 6 axis chips.
I then wanted to know if inertial navigation was possible (so no GPS but just by recording the MEMS output)
After asking in some some group I ran a drift experiment on that chip, using its internal sensor
to stabilize temperature
then ran some drift tests
http://panteltje.com/pub/acceleration_x_40000_seconds.gif
http://panteltje.com/pub/acceleration_y_40000_seconds.gif
http://panteltje.com/pub/acceleration_z_40000_seconds.gif
I also wanted to know if I could detect the moon orbiting from G measurement with that chip:
http://panteltje.com/pub/z_to_21_8_2015_8_35.gif
from that data I concluded what I was seeing was day-night temperature variation in spite of using the chips internal temperature
sensor to keep it at a fixed temperature.
Thinking about that, it seemed to me PCB temperature change does put mechanical stress on the chip, could be an explanation.
Then some uni repeated that experiment with the whole thing in a temp controlled oven.
IMO that was a good move,, usually those projects then go silent as DOD gets interested,
I went on to playing with the next interesting thing.....
But big mechanical giros (V2?) or laser giros (bit later)? or MEMS ?
MEMS may be good enough,
>The mechanical gyros are accepted because they have been around for
>many decades.
So have been camp fires :-)
Personally I use a microwave.
Jan Panteltje
Feb 11, 2021, 1:53:17 AM2/11/21
to
On a sunny day (Wed, 10 Feb 2021 17:58:24 +0000 (UTC)) it happened
DecadentLinux...@decadence.org wrote in
<s016rv$1a9g$1...@gioia.aioe.org>:
Nice!
DecadentLinux...@decadence.org wrote in
<s016rv$1a9g$1...@gioia.aioe.org>:
jla...@highlandsniptechnology.com
Feb 11, 2021, 6:19:51 AM2/11/21
to
On Wed, 10 Feb 2021 20:14:25 -0000 (UTC), Steve Wilson <sp...@me.com>
wrote:
The guy was an aerobatics instructor. He'd fly radically for an hour
at a time, which probably affected gyros. I don't get motion sick, but
an hour with him before lunch did reduce my appetite.
We's steal cheap toilet paper from work, unfurl a roll at 7000 feet,
and see how many times we could cut it in half before it (or we) hit
Lake Pontchartrain.
wrote:
at a time, which probably affected gyros. I don't get motion sick, but
an hour with him before lunch did reduce my appetite.
We's steal cheap toilet paper from work, unfurl a roll at 7000 feet,
and see how many times we could cut it in half before it (or we) hit
Lake Pontchartrain.
Jan Panteltje
Feb 11, 2021, 6:33:11 AM2/11/21
to
On a sunny day (Thu, 11 Feb 2021 03:19:41 -0800) it happened
jla...@highlandsniptechnology.com wrote in
<vb4a2g519jmqesgfr...@4ax.com>:
>We's steal cheap toilet paper from work, unfurl a roll at 7000 feet,
>and see how many times we could cut it in half before it (or we) hit
>Lake Pontchartrain.
We'd teleport to Mars before dinner to gets some Martian rabbits:
http://panteltje.com/panteltje/space/mars/easthills-bunny.jpg
jla...@highlandsniptechnology.com wrote in
<vb4a2g519jmqesgfr...@4ax.com>:
>We's steal cheap toilet paper from work, unfurl a roll at 7000 feet,
>and see how many times we could cut it in half before it (or we) hit
>Lake Pontchartrain.
http://panteltje.com/panteltje/space/mars/easthills-bunny.jpg
Jan Panteltje
Feb 11, 2021, 10:07:56 AM2/11/21
to
On a sunny day (Thu, 11 Feb 2021 14:36:59 +0000) it happened Peter
<nos...@nospam9876.com> wrote in <s03fed$o13$1...@dont-email.me>:
>
> Jan Panteltje <pNaOnSt...@yahoo.com> wrote:
>
>>But big mechanical giros (V2?) or laser giros (bit later)? or MEMS ?
>>MEMS may be good enough,
>
>Lots of people have been trying to do this, using solid state devices
>for navigation, and it is no good by a factor of 100+. Maybe one day.
>
>Too much drift.
>
>The temp stabilisation, typically +65C, doesn't produce very reliable
>electronics too, due to the thermal cycling.
Since I actually measured that stuff I have to disagree.
As to thermal cycling, why cycle?
My project with that raspberry pi had an uptime of > 220 days or so,
could have left it on, but was moving house, now it is back on on a UPS.
The tritium decay project with build in temp control was on for many years
from 2013 to end of last year:
http://panteltje.com/panteltje/tri_pic/
full battery backup (twice, added lipos later), stopped only because I had enough data.
All these small things need very little power to keep at some elevated temperature.
MEMS...
TCXOs
etc
There are often simple solutions for all those, often hypothetical, problems.
<nos...@nospam9876.com> wrote in <s03fed$o13$1...@dont-email.me>:
>
> Jan Panteltje <pNaOnSt...@yahoo.com> wrote:
>
>>But big mechanical giros (V2?) or laser giros (bit later)? or MEMS ?
>>MEMS may be good enough,
>
>for navigation, and it is no good by a factor of 100+. Maybe one day.
>
>Too much drift.
>
>The temp stabilisation, typically +65C, doesn't produce very reliable
>electronics too, due to the thermal cycling.
Since I actually measured that stuff I have to disagree.
As to thermal cycling, why cycle?
My project with that raspberry pi had an uptime of > 220 days or so,
could have left it on, but was moving house, now it is back on on a UPS.
The tritium decay project with build in temp control was on for many years
from 2013 to end of last year:
http://panteltje.com/panteltje/tri_pic/
full battery backup (twice, added lipos later), stopped only because I had enough data.
All these small things need very little power to keep at some elevated temperature.
MEMS...
TCXOs
etc
There are often simple solutions for all those, often hypothetical, problems.
jla...@highlandsniptechnology.com
Feb 11, 2021, 11:44:13 AM2/11/21
to
On Thu, 11 Feb 2021 14:38:54 +0000, Peter <nos...@nospam9876.com>
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>The guy was an aerobatics instructor. He'd fly radically for an hour
>>at a time, which probably affected gyros. I don't get motion sick, but
>>an hour with him before lunch did reduce my appetite.
>
>Yes; you can't do this with mechanical gyros. They topple, hit stops,
>etc.
I noticed that he liked to do rolls clockwise, which probably biased
the gyros.
Frank had a wild snap roll. He let me fly straight up into a vertical
stall and come down backwards. That was cool.
I'm guessing that an artificial horizon is a slow averaging response
to the gravity vector, so maneuvers can fool it. No affordable gyro is
going to be set on the ground and remain pointed at the center of the
earth for long, especially in a Aerobat.
MEMS accelerometers probably use electronic averaging, same problem.
Time constants are apparently in the minutes range.
There must be wires or slip rings or something to power the gyro in an
artificial horizon. Shipboard gyrocompasses float their gyro inside a
sphere, in a pool of conductive liquid, and use the liquid for
conduction. So there's no friction. But people don't fly ships upside
down.
wrote:
>
> jla...@highlandsniptechnology.com wrote:
>
>>The guy was an aerobatics instructor. He'd fly radically for an hour
>>at a time, which probably affected gyros. I don't get motion sick, but
>>an hour with him before lunch did reduce my appetite.
>
>etc.
I noticed that he liked to do rolls clockwise, which probably biased
the gyros.
Frank had a wild snap roll. He let me fly straight up into a vertical
stall and come down backwards. That was cool.
I'm guessing that an artificial horizon is a slow averaging response
to the gravity vector, so maneuvers can fool it. No affordable gyro is
going to be set on the ground and remain pointed at the center of the
earth for long, especially in a Aerobat.
MEMS accelerometers probably use electronic averaging, same problem.
Time constants are apparently in the minutes range.
There must be wires or slip rings or something to power the gyro in an
artificial horizon. Shipboard gyrocompasses float their gyro inside a
sphere, in a pool of conductive liquid, and use the liquid for
conduction. So there's no friction. But people don't fly ships upside
down.
Steve Wilson
Feb 11, 2021, 12:17:48 PM2/11/21
to
anywhere, just up and down. Save the wear and tear. Cage the attitude
indicator.
Jan Panteltje
Feb 11, 2021, 12:19:38 PM2/11/21
to
On a sunny day (Thu, 11 Feb 2021 08:44:04 -0800) it happened
jla...@highlandsniptechnology.com wrote in
<2rma2gps57jgj9grd...@4ax.com>:
>On Thu, 11 Feb 2021 14:38:54 +0000, Peter <nos...@nospam9876.com>
>wrote:
>
>>
>> jla...@highlandsniptechnology.com wrote:
>>
>>>The guy was an aerobatics instructor. He'd fly radically for an hour
>>>at a time, which probably affected gyros. I don't get motion sick, but
>>>an hour with him before lunch did reduce my appetite.
>>
>>Yes; you can't do this with mechanical gyros. They topple, hit stops,
>>etc.
>
>I noticed that he liked to do rolls clockwise, which probably biased
>the gyros.
>
>Frank had a wild snap roll. He let me fly straight up into a vertical
>stall and come down backwards. That was cool.
>
>I'm guessing that an artificial horizon is a slow averaging response
>to the gravity vector, so maneuvers can fool it. No affordable gyro is
>going to be set on the ground and remain pointed at the center of the
>earth for long, especially in a Aerobat.
>
>MEMS accelerometers probably use electronic averaging, same problem.
>Time constants are apparently in the minutes range.
You are aware that those chips are in every [toy] drone right?
reaction time is milliseconds, to keep the thing horizontal.
From
MPU-6000/MPU-6050 Product Specification; (PS-MPU-6000A.pdf google it)
5 Features
5.1 Gyroscope Features
The triple-axis MEMS gyroscope in the MPU-60X0 includes a wide range of features:
Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with a user-programmable full-
scale range of ±250, ±500, ±1000, and ±2000°/sec
External sync signal connected to the FSYNC pin supports image, video and GPS synchronization
Integrated 16-bit ADCs enable simultaneous sampling of gyros
Enhanced bias and sensitivity temperature stability reduces the need for user calibration
Improved low-frequency noise performance
Digitally-programmable low-pass filter
Gyroscope operating current: 3.6mA
Standby current: 5µA
Factory calibrated sensitivity scale factor
User self-test
5.2 Accelerometer Features
...
-------
It also says:
"The part features a robust 10,000g shock tolerance, and has programmable low-pass
filters for the gyroscopes, accelerometers, and the on-chip temperature sensor."
------
10,000 g is a lot...
And that is an older chip, I am sure better ones are now available.
And no I have connection and have no shares in InvenSense...
jla...@highlandsniptechnology.com wrote in
<2rma2gps57jgj9grd...@4ax.com>:
>On Thu, 11 Feb 2021 14:38:54 +0000, Peter <nos...@nospam9876.com>
>wrote:
>
>>
>> jla...@highlandsniptechnology.com wrote:
>>
>>>The guy was an aerobatics instructor. He'd fly radically for an hour
>>>at a time, which probably affected gyros. I don't get motion sick, but
>>>an hour with him before lunch did reduce my appetite.
>>
>>Yes; you can't do this with mechanical gyros. They topple, hit stops,
>>etc.
>
>I noticed that he liked to do rolls clockwise, which probably biased
>the gyros.
>
>Frank had a wild snap roll. He let me fly straight up into a vertical
>stall and come down backwards. That was cool.
>
>I'm guessing that an artificial horizon is a slow averaging response
>to the gravity vector, so maneuvers can fool it. No affordable gyro is
>going to be set on the ground and remain pointed at the center of the
>earth for long, especially in a Aerobat.
>
>MEMS accelerometers probably use electronic averaging, same problem.
>Time constants are apparently in the minutes range.
reaction time is milliseconds, to keep the thing horizontal.
From
MPU-6000/MPU-6050 Product Specification; (PS-MPU-6000A.pdf google it)
5 Features
5.1 Gyroscope Features
The triple-axis MEMS gyroscope in the MPU-60X0 includes a wide range of features:
Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with a user-programmable full-
scale range of ±250, ±500, ±1000, and ±2000°/sec
External sync signal connected to the FSYNC pin supports image, video and GPS synchronization
Integrated 16-bit ADCs enable simultaneous sampling of gyros
Enhanced bias and sensitivity temperature stability reduces the need for user calibration
Improved low-frequency noise performance
Digitally-programmable low-pass filter
Gyroscope operating current: 3.6mA
Standby current: 5µA
Factory calibrated sensitivity scale factor
User self-test
5.2 Accelerometer Features
...
-------
It also says:
"The part features a robust 10,000g shock tolerance, and has programmable low-pass
filters for the gyroscopes, accelerometers, and the on-chip temperature sensor."
------
10,000 g is a lot...
And that is an older chip, I am sure better ones are now available.
And no I have connection and have no shares in InvenSense...
Tauno Voipio
Feb 11, 2021, 12:43:58 PM2/11/21
to
constants of minutes in digital processing of electronic sensors.
The traditional aircraft gyros run on air pressure, or actually suction.
There is usually a vacuum indicating instrument on the panel for
monitoring.
For redundancy, the turn rate indicator is usually electrically driven.
Due to the limited movement of the gyro frame, it is pretty easy to
feed electricity to the motor without needing brushes.
--
-TV
jla...@highlandsniptechnology.com
Feb 11, 2021, 12:48:53 PM2/11/21
to
center of the earth. People die from that difference.
I wonder if the electronic attitude indicators have a manual zero
reset button. Something has to reset the integrators.
>
>From
> MPU-6000/MPU-6050 Product Specification; (PS-MPU-6000A.pdf google it)
>5 Features
>5.1 Gyroscope Features
>The triple-axis MEMS gyroscope in the MPU-60X0 includes a wide range of features:
> Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with a user-programmable full-
> External sync signal connected to the FSYNC pin supports image, video and GPS synchronization
> Integrated 16-bit ADCs enable simultaneous sampling of gyros
> Enhanced bias and sensitivity temperature stability reduces the need for user calibration
> Improved low-frequency noise performance
> Digitally-programmable low-pass filter
> Gyroscope operating current: 3.6mA
> Standby current: 5ľA
> Integrated 16-bit ADCs enable simultaneous sampling of gyros
> Enhanced bias and sensitivity temperature stability reduces the need for user calibration
> Improved low-frequency noise performance
> Digitally-programmable low-pass filter
> Gyroscope operating current: 3.6mA
> Factory calibrated sensitivity scale factor
> User self-test
>5.2 Accelerometer Features
>...
>-------
>It also says:
>"The part features a robust 10,000g shock tolerance, and has programmable low-pass
> filters for the gyroscopes, accelerometers, and the on-chip temperature sensor."
>------
>10,000 g is a lot...
>
>And that is an older chip, I am sure better ones are now available.
>And no I have connection and have no shares in InvenSense...
>
An accelerometer doesn't tell you if you are horizontal. It tell you
> User self-test
>5.2 Accelerometer Features
>...
>-------
>It also says:
>"The part features a robust 10,000g shock tolerance, and has programmable low-pass
> filters for the gyroscopes, accelerometers, and the on-chip temperature sensor."
>------
>10,000 g is a lot...
>
>And that is an older chip, I am sure better ones are now available.
>And no I have connection and have no shares in InvenSense...
>
that you think you are horizontal.
jla...@highlandsniptechnology.com
Feb 11, 2021, 12:50:37 PM2/11/21
to
On Thu, 11 Feb 2021 17:17:43 -0000 (UTC), Steve Wilson <sp...@me.com>
Beats me. I just saw him tweak the instrument now and then, in rare
moments of level flight.
moments of level flight.
Steve Wilson
Feb 11, 2021, 12:57:04 PM2/11/21
to
Tauno Voipio <tauno....@notused.fi.invalid> wrote:
[...]
> The traditional aircraft gyros run on air pressure, or actually suction.
> There is usually a vacuum indicating instrument on the panel for
> monitoring.
The venturi are subject to icing, so they fail when you need them the the
most.
Pitot tubes for airspeed indicators are also subject to icing, which brought
down air France flight 447. They did not turn on the pitot heaters.
> For redundancy, the turn rate indicator is usually electrically driven.
> Due to the limited movement of the gyro frame, it is pretty easy to
> feed electricity to the motor without needing brushes.
Wires bias the gyro frame leading to precession which generates error.
The Malibu has a vacuum pump to drive the attitude indicator. There are no
wires attached to the gyro.
[...]
> The traditional aircraft gyros run on air pressure, or actually suction.
> There is usually a vacuum indicating instrument on the panel for
> monitoring.
most.
Pitot tubes for airspeed indicators are also subject to icing, which brought
down air France flight 447. They did not turn on the pitot heaters.
> For redundancy, the turn rate indicator is usually electrically driven.
> Due to the limited movement of the gyro frame, it is pretty easy to
> feed electricity to the motor without needing brushes.
The Malibu has a vacuum pump to drive the attitude indicator. There are no
wires attached to the gyro.
Tauno Voipio
Feb 11, 2021, 1:10:21 PM2/11/21
to
On 11.2.21 19.56, Steve Wilson wrote:
> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
> [...]
>
>> The traditional aircraft gyros run on air pressure, or actually suction.
>> There is usually a vacuum indicating instrument on the panel for
>> monitoring.
>
> The venturi are subject to icing, so they fail when you need them the the
> most.
The gyro vacuum is generated by engine-driven vacuum pump(s).
> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
> [...]
>
>> The traditional aircraft gyros run on air pressure, or actually suction.
>> There is usually a vacuum indicating instrument on the panel for
>> monitoring.
>
> The venturi are subject to icing, so they fail when you need them the the
> most.
> Pitot tubes for airspeed indicators are also subject to icing, which brought
> down air France flight 447. They did not turn on the pitot heaters.
zero, though I was sure that I was still flying. This happened despite
of the pitot heating being on. The plane was flyable by the groundspeed
indications from the navigation system.
>> For redundancy, the turn rate indicator is usually electrically driven.
>> Due to the limited movement of the gyro frame, it is pretty easy to
>> feed electricity to the motor without needing brushes.
>
> Wires bias the gyro frame leading to precession which generates error.
gyros. There are intentional springs limiting the gyro frame movement.
--
-TV
John Larkin
Feb 11, 2021, 1:44:08 PM2/11/21
to
things now and then.
Tauno Voipio
Feb 11, 2021, 2:07:26 PM2/11/21
to
the attitude gyro ('artigicial horizon').
The turn indicator is set to respond to angular velocity around the
airplane's vertical axis, and it does not need to be reset.
--
-TV
Jan Panteltje
Feb 11, 2021, 2:13:55 PM2/11/21
to
On a sunny day (Thu, 11 Feb 2021 09:48:44 -0800) it happened
jla...@highlandsniptechnology.com wrote in
<85ra2glu2a3k7bqim...@4ax.com>:
>On Thu, 11 Feb 2021 17:16:38 GMT, Jan Panteltje
><pNaOnSt...@yahoo.com> wrote:
>>You are aware that those chips are in every [toy] drone right?
>>reaction time is milliseconds, to keep the thing horizontal.
>But in a moving airplane, the gravity vector does not point at the
>center of the earth. People die from that difference.
Drones move too ,and fast sometimes
>I wonder if the electronic attitude indicators have a manual zero
>reset button. Something has to reset the integrators.
The 'reset' in my Hubsan drone is before you take off,
you leave it a few seconds standing on the ground for horizontal gyro calibration.
then rotate the thing horizontal for compass, then around vertical axis for compass (3 axis compass),
For a quad drone to move in some direction it has to slightly tilt forward in that direction:
Not to scale:
\
0 --->
\
So all you change is attitude, here now the air stream from the props is going to the left., and the thing to the right.
>An accelerometer doesn't tell you if you are horizontal. It tell you
>that you think you are horizontal.
The chip has both an accelerometer AND a gyroscope.
quote:
"
The MPU-60X0 is the world's first integrated 6-axis MotionTracking device that combines a 3-axis
gyroscope, 3-axis accelerometer, and a Digital Motion ProcessorTM (DMP) all in a small 4x4x0.9mm
package. With its dedicated I C sensor bus, it directly accepts inputs from an external 3-axis compass to
provide a complete 9-axis MotionFusionTM output.
...
"
So far my drone has had no problems with all this, and I did some wild things with it.
http://panteltje.com/panteltje/quadcopter/index.html
Have not tried flying upside down. would require the propellers to turn the other way...
You can find out for yerself.
https://www.ebay.com/itm/201415045005
1$23
more than 10,000 sold....
jla...@highlandsniptechnology.com wrote in
<85ra2glu2a3k7bqim...@4ax.com>:
>On Thu, 11 Feb 2021 17:16:38 GMT, Jan Panteltje
><pNaOnSt...@yahoo.com> wrote:
>>You are aware that those chips are in every [toy] drone right?
>>reaction time is milliseconds, to keep the thing horizontal.
>But in a moving airplane, the gravity vector does not point at the
>center of the earth. People die from that difference.
>I wonder if the electronic attitude indicators have a manual zero
>reset button. Something has to reset the integrators.
you leave it a few seconds standing on the ground for horizontal gyro calibration.
then rotate the thing horizontal for compass, then around vertical axis for compass (3 axis compass),
For a quad drone to move in some direction it has to slightly tilt forward in that direction:
Not to scale:
\
0 --->
\
So all you change is attitude, here now the air stream from the props is going to the left., and the thing to the right.
>An accelerometer doesn't tell you if you are horizontal. It tell you
>that you think you are horizontal.
quote:
"
The MPU-60X0 is the world's first integrated 6-axis MotionTracking device that combines a 3-axis
gyroscope, 3-axis accelerometer, and a Digital Motion ProcessorTM (DMP) all in a small 4x4x0.9mm
package. With its dedicated I C sensor bus, it directly accepts inputs from an external 3-axis compass to
provide a complete 9-axis MotionFusionTM output.
...
"
So far my drone has had no problems with all this, and I did some wild things with it.
http://panteltje.com/panteltje/quadcopter/index.html
Have not tried flying upside down. would require the propellers to turn the other way...
You can find out for yerself.
https://www.ebay.com/itm/201415045005
1$23
more than 10,000 sold....
Steve Wilson
Feb 11, 2021, 2:49:13 PM2/11/21
to
Tauno Voipio <tauno....@notused.fi.invalid> wrote:
> On 11.2.21 19.56, Steve Wilson wrote:
>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>
>> [...]
>>
>>> The traditional aircraft gyros run on air pressure, or actually
>>> suction. There is usually a vacuum indicating instrument on the panel
>>> for monitoring.
>>
>> The venturi are subject to icing, so they fail when you need them the
>> the most.
>
> The gyro vacuum is generated by engine-driven vacuum pump(s).
The Malibu has twin turbochargers. There is no vacuum available.
> On 11.2.21 19.56, Steve Wilson wrote:
>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>
>> [...]
>>
>>> The traditional aircraft gyros run on air pressure, or actually
>>> suction. There is usually a vacuum indicating instrument on the panel
>>> for monitoring.
>>
>> The venturi are subject to icing, so they fail when you need them the
>> the most.
>
> The gyro vacuum is generated by engine-driven vacuum pump(s).
>> Pitot tubes for airspeed indicators are also subject to icing, which
>> brought down air France flight 447. They did not turn on the pitot
>> heaters.
> I have seen in-flight that the airspeed indication slowly dropped to
> zero, though I was sure that I was still flying. This happened despite
> of the pitot heating being on. The plane was flyable by the groundspeed
> indications from the navigation system.
flight.
>>> For redundancy, the turn rate indicator is usually electrically
>>> driven. Due to the limited movement of the gyro frame, it is pretty
>>> easy to feed electricity to the motor without needing brushes.
>>
>> Wires bias the gyro frame leading to precession which generates error.
>
> The turn indicator is a different beast thn the heading and attitude
> gyros. There are intentional springs limiting the gyro frame movement.
gyro. It is driven by vacuum. Venturis are subject to icing. The Malibu has
a vacuum pump, one for each pilot seat.
Clifford Heath
Feb 11, 2021, 5:53:47 PM2/11/21
to
suffer gimbal lock if they get to 90 degrees from horizontal. The more
advanced ones use quaternions, and so can still work upside-down.
It's usual to have GPS, compass (magnetometer), gyro and accelerometers,
and to fuse all those with a Kalman filter.
Check the code of px4 to know how it should be done.
CH
Jan Panteltje
Feb 12, 2021, 1:55:27 AM2/12/21
to
On a sunny day (Fri, 12 Feb 2021 09:53:39 +1100) it happened Clifford Heath
<no....@please.net> wrote in <VziVH.11085$LL1....@fx33.iad>:
Explain to me how you then reverse propeller direction,
when you turn the thing 'upside down' it pushes the air upwards and digs a hole into the ground..
Of course for this Hubsan anything near 90 degrees is out of the question.
Basically you need more downward directed air to keep the weight up there, and a relative
much smaller amount to move forward (in horizontal direction relative to earth I mean).
That is why I wrote 'not to scale'.
In the youtube video you see this drone flying slowly horizontal and you cannot even see the tilt.
The software (in this case reading simulated GPS data) limits the horizontal speed and sets the position in 3D from second to second.
Load dropping:
https://www.youtube.com/watch?v=bI_0mjwlvNw
>It's usual to have GPS, compass (magnetometer), gyro and accelerometers,
>and to fuse all those with a Kalman filter.
Yes
<no....@please.net> wrote in <VziVH.11085$LL1....@fx33.iad>:
when you turn the thing 'upside down' it pushes the air upwards and digs a hole into the ground..
Of course for this Hubsan anything near 90 degrees is out of the question.
Basically you need more downward directed air to keep the weight up there, and a relative
much smaller amount to move forward (in horizontal direction relative to earth I mean).
That is why I wrote 'not to scale'.
In the youtube video you see this drone flying slowly horizontal and you cannot even see the tilt.
The software (in this case reading simulated GPS data) limits the horizontal speed and sets the position in 3D from second to second.
Load dropping:
https://www.youtube.com/watch?v=bI_0mjwlvNw
>It's usual to have GPS, compass (magnetometer), gyro and accelerometers,
>and to fuse all those with a Kalman filter.
Tauno Voipio
Feb 12, 2021, 6:22:05 AM2/12/21
to
On 11.2.21 21.49, Steve Wilson wrote:
> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
>> On 11.2.21 19.56, Steve Wilson wrote:
>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>>
>>> [...]
>>>
>>>> The traditional aircraft gyros run on air pressure, or actually
>>>> suction. There is usually a vacuum indicating instrument on the panel
>>>> for monitoring.
>>>
>>> The venturi are subject to icing, so they fail when you need them the
>>> the most.
>>
>> The gyro vacuum is generated by engine-driven vacuum pump(s).
>
> The Malibu has twin turbochargers. There is no vacuum available.
>
>>> Pitot tubes for airspeed indicators are also subject to icing, which
>>> brought down air France flight 447. They did not turn on the pitot
>>> heaters.
>
>> I have seen in-flight that the airspeed indication slowly dropped to
>> zero, though I was sure that I was still flying. This happened despite
>> of the pitot heating being on. The plane was flyable by the groundspeed
>> indications from the navigation system.
>
> Something is wrong with your plane. It must be fxed before your next
> flight.
The airplane was OK (Piper Turbo Arrow IV) and verified airworthy.
> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
>> On 11.2.21 19.56, Steve Wilson wrote:
>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>>
>>> [...]
>>>
>>>> The traditional aircraft gyros run on air pressure, or actually
>>>> suction. There is usually a vacuum indicating instrument on the panel
>>>> for monitoring.
>>>
>>> The venturi are subject to icing, so they fail when you need them the
>>> the most.
>>
>> The gyro vacuum is generated by engine-driven vacuum pump(s).
>
> The Malibu has twin turbochargers. There is no vacuum available.
>
>>> Pitot tubes for airspeed indicators are also subject to icing, which
>>> brought down air France flight 447. They did not turn on the pitot
>>> heaters.
>
>> I have seen in-flight that the airspeed indication slowly dropped to
>> zero, though I was sure that I was still flying. This happened despite
>> of the pitot heating being on. The plane was flyable by the groundspeed
>> indications from the navigation system.
>
> Something is wrong with your plane. It must be fxed before your next
> flight.
It seems that you've never been on Finnish winter sky.
>>>> For redundancy, the turn rate indicator is usually electrically
>>>> driven. Due to the limited movement of the gyro frame, it is pretty
>>>> easy to feed electricity to the motor without needing brushes.
>>>
>>> Wires bias the gyro frame leading to precession which generates error.
>>
>> The turn indicator is a different beast thn the heading and attitude
>> gyros. There are intentional springs limiting the gyro frame movement.
>
> We are talking about the attitude indicator. There are no wires to the
> gyro. It is driven by vacuum. Venturis are subject to icing. The Malibu has
> a vacuum pump, one for each pilot seat.
I wrote.
--
-TV
Clifford Heath
Feb 12, 2021, 6:37:54 AM2/12/21
to
On 12/2/21 5:52 pm, Jan Panteltje wrote:
> On a sunny day (Fri, 12 Feb 2021 09:53:39 +1100) it happened Clifford Heath
> <no....@please.net> wrote in <VziVH.11085$LL1....@fx33.iad>:
>
>> On 12/2/21 6:10 am, Jan Panteltje wrote:
>>> The chip has both an accelerometer AND a gyroscope.
>>> quote:
>>> "
>>> The MPU-60X0 is the world's first integrated 6-axis MotionTracking device that combines a 3-axis
>>> gyroscope, 3-axis accelerometer, and a Digital Motion ProcessorTM (DMP) all in a small 4x4x0.9mm
>>> package. With its dedicated I C sensor bus, it directly accepts inputs from an external 3-axis compass to
>>> provide a complete 9-axis MotionFusionTM output.
>>> ...
>>> "
>>>
>>> So far my drone has had no problems with all this, and I did some wild things with it.
>>> http://panteltje.com/panteltje/quadcopter/index.html
>>>
>>> Have not tried flying upside down. would require the propellers to turn the other way...
>>> You can find out for yerself.
>>> https://www.ebay.com/itm/201415045005
>> AIUI, some drone IMU software used normal 3D coordinates and would
>> suffer gimbal lock if they get to 90 degrees from horizontal. The more
>> advanced ones use quaternions, and so can still work upside-down.
>
> Explain to me how you then reverse propeller direction,
I'm not sure how that needs explaining. Obviously when the gravity
> On a sunny day (Fri, 12 Feb 2021 09:53:39 +1100) it happened Clifford Heath
> <no....@please.net> wrote in <VziVH.11085$LL1....@fx33.iad>:
>
>> On 12/2/21 6:10 am, Jan Panteltje wrote:
>>> The chip has both an accelerometer AND a gyroscope.
>>> quote:
>>> "
>>> The MPU-60X0 is the world's first integrated 6-axis MotionTracking device that combines a 3-axis
>>> gyroscope, 3-axis accelerometer, and a Digital Motion ProcessorTM (DMP) all in a small 4x4x0.9mm
>>> package. With its dedicated I C sensor bus, it directly accepts inputs from an external 3-axis compass to
>>> provide a complete 9-axis MotionFusionTM output.
>>> ...
>>> "
>>>
>>> So far my drone has had no problems with all this, and I did some wild things with it.
>>> http://panteltje.com/panteltje/quadcopter/index.html
>>>
>>> Have not tried flying upside down. would require the propellers to turn the other way...
>>> You can find out for yerself.
>>> https://www.ebay.com/itm/201415045005
>> AIUI, some drone IMU software used normal 3D coordinates and would
>> suffer gimbal lock if they get to 90 degrees from horizontal. The more
>> advanced ones use quaternions, and so can still work upside-down.
>
> Explain to me how you then reverse propeller direction,
vector is reversed the thrust must be also. The props aren't so
efficient in the reverse direction either, and the control algorithm
must take account of that.
I've seen video of a drone that can flip like this, but it's regarded as
quite unusual. I don't think it's done by manual control - but by a
pre-programmed flip manoeuvre commanded by a pushbutton.
CH
Jan Panteltje
Feb 12, 2021, 7:57:38 AM2/12/21
to
On a sunny day (Fri, 12 Feb 2021 22:37:45 +1100) it happened Clifford Heath
<no....@please.net> wrote in <fMtVH.1052$z%1....@fx03.iad>:
>>> On 12/2/21 6:10 am, Jan Panteltje wrote:
>> Explain to me how you then reverse propeller direction,
>
>I'm not sure how that needs explaining. Obviously when the gravity
>vector is reversed the thrust must be also. The props aren't so
>efficient in the reverse direction either, and the control algorithm
>must take account of that.
>
>I've seen video of a drone that can flip like this, but it's regarded as
>quite unusual. I don't think it's done by manual control - but by a
>pre-programmed flip manoeuvre commanded by a pushbutton.
Maybe just for show ? Does not make much sense to me.
Much better shows are the ones China does with drones in formation:
https://www.youtube.com/watch?v=VnTQTm7vNbY
Is quite easy actually using that software I wrote to control the Hubsan
but I only have one.
EU now has, from the start of this year, new drone regulations and you have to get a license
plus pass some tests, pay for it of course, thing needs an ID transmitter,
just the usual fascist control trip by a bunch of old women brought into
politics that are afraid of everything from cats to kitchen knives.
I think I played enough and have a good attack system against their F35 whatever follies.
https://www.rt.com/news/515261-israel-missile-drones-asia-investigation/
;-)
Sometimes it is better to be a pirate.
Just imagine 100 toy drones appearing out of nowhere in front of an F35 taking off here locally.
Hell it was already declared damaged when the fire brigade on the airport showered it with foam as welcome!
http://panteltje.com/pub/first_F35_was_on_fire_it_seems_IXIMG_0228.JPG
Cost compare....
?? agent has ...
fuck the high tech
I am beginning to miss trump!
We need wars to get rid of all the crap, especially all the US fake weapons
but likely US will turn black, those multiply faster, due to their lower
IQ but higher numbers they will grab power and claim they invented the wheel
and everything after that, remove all references to how things really happened
and black ages will start.
I see similar crap happening here too, it is like a poison, whites start imitating it
and there goes civilization (note the shit babble music for example).
CO2 crap, vaccines crap, green crap, sex equality crap, media censoring crap,
total control of you and your data crap,
printing money 24/7 to help everybody crap, lock-downs, no free speech (testing),
<no....@please.net> wrote in <fMtVH.1052$z%1....@fx03.iad>:
>>> On 12/2/21 6:10 am, Jan Panteltje wrote:
>> Explain to me how you then reverse propeller direction,
>
>I'm not sure how that needs explaining. Obviously when the gravity
>vector is reversed the thrust must be also. The props aren't so
>efficient in the reverse direction either, and the control algorithm
>must take account of that.
>
>I've seen video of a drone that can flip like this, but it's regarded as
>quite unusual. I don't think it's done by manual control - but by a
>pre-programmed flip manoeuvre commanded by a pushbutton.
Much better shows are the ones China does with drones in formation:
https://www.youtube.com/watch?v=VnTQTm7vNbY
Is quite easy actually using that software I wrote to control the Hubsan
but I only have one.
EU now has, from the start of this year, new drone regulations and you have to get a license
plus pass some tests, pay for it of course, thing needs an ID transmitter,
just the usual fascist control trip by a bunch of old women brought into
politics that are afraid of everything from cats to kitchen knives.
I think I played enough and have a good attack system against their F35 whatever follies.
https://www.rt.com/news/515261-israel-missile-drones-asia-investigation/
;-)
Sometimes it is better to be a pirate.
Just imagine 100 toy drones appearing out of nowhere in front of an F35 taking off here locally.
Hell it was already declared damaged when the fire brigade on the airport showered it with foam as welcome!
http://panteltje.com/pub/first_F35_was_on_fire_it_seems_IXIMG_0228.JPG
Cost compare....
?? agent has ...
fuck the high tech
I am beginning to miss trump!
We need wars to get rid of all the crap, especially all the US fake weapons
but likely US will turn black, those multiply faster, due to their lower
IQ but higher numbers they will grab power and claim they invented the wheel
and everything after that, remove all references to how things really happened
and black ages will start.
I see similar crap happening here too, it is like a poison, whites start imitating it
and there goes civilization (note the shit babble music for example).
CO2 crap, vaccines crap, green crap, sex equality crap, media censoring crap,
total control of you and your data crap,
printing money 24/7 to help everybody crap, lock-downs, no free speech (testing),
Steve Wilson
Feb 12, 2021, 9:41:07 AM2/12/21
to
Tauno Voipio <tauno....@notused.fi.invalid> wrote:
> On 11.2.21 21.49, Steve Wilson wrote:
>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>
>>> On 11.2.21 19.56, Steve Wilson wrote:
>>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
[...]
> On 11.2.21 21.49, Steve Wilson wrote:
>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>
>>> On 11.2.21 19.56, Steve Wilson wrote:
>>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
[...]
>>> I have seen in-flight that the airspeed indication slowly dropped to
>>> zero, though I was sure that I was still flying. This happened despite
>>> of the pitot heating being on. The plane was flyable by the
>>> groundspeed indications from the navigation system.
>>
>> Something is wrong with your plane. It must be fxed before your next
>> flight.
>
> The airplane was OK (Piper Turbo Arrow IV) and verified airworthy.
> It seems that you've never been on Finnish winter sky.
An airspeed indication of zero while you are flying clearly shows something
>>> zero, though I was sure that I was still flying. This happened despite
>>> of the pitot heating being on. The plane was flyable by the
>>> groundspeed indications from the navigation system.
>>
>> Something is wrong with your plane. It must be fxed before your next
>> flight.
>
> The airplane was OK (Piper Turbo Arrow IV) and verified airworthy.
> It seems that you've never been on Finnish winter sky.
is wrong with your plane. It cannot be certified airworthy.
It doesn't matter if you are in Finland or anywhere else. You cannot fly
with an airspeed indicator that reads zero.
[...]
>> We are talking about the attitude indicator. There are no wires to the
>> gyro. It is driven by vacuum. Venturis are subject to icing. The Malibu
>> has a vacuum pump, one for each pilot seat.
> It seems that you did not read my previous posts. It is exactly what
> I wrote.
Tauno Voipio
Feb 12, 2021, 2:12:46 PM2/12/21
to
On 12.2.21 16.41, Steve Wilson wrote:
> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
>> On 11.2.21 21.49, Steve Wilson wrote:
>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>>
>>>> On 11.2.21 19.56, Steve Wilson wrote:
>>>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
> [...]
>
>>>> I have seen in-flight that the airspeed indication slowly dropped to
>>>> zero, though I was sure that I was still flying. This happened despite
>>>> of the pitot heating being on. The plane was flyable by the
>>>> groundspeed indications from the navigation system.
>>>
>>> Something is wrong with your plane. It must be fxed before your next
>>> flight.
>>
>> The airplane was OK (Piper Turbo Arrow IV) and verified airworthy.
>> It seems that you've never been on Finnish winter sky.
>
> An airspeed indication of zero while you are flying clearly shows something
> is wrong with your plane. It cannot be certified airworthy.
>
> It doesn't matter if you are in Finland or anywhere else. You cannot fly
> with an airspeed indicator that reads zero.
It seems that you have never met severe icing.
> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
>> On 11.2.21 21.49, Steve Wilson wrote:
>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>>>
>>>> On 11.2.21 19.56, Steve Wilson wrote:
>>>>> Tauno Voipio <tauno....@notused.fi.invalid> wrote:
>
> [...]
>
>>>> I have seen in-flight that the airspeed indication slowly dropped to
>>>> zero, though I was sure that I was still flying. This happened despite
>>>> of the pitot heating being on. The plane was flyable by the
>>>> groundspeed indications from the navigation system.
>>>
>>> Something is wrong with your plane. It must be fxed before your next
>>> flight.
>>
>> The airplane was OK (Piper Turbo Arrow IV) and verified airworthy.
>> It seems that you've never been on Finnish winter sky.
>
> An airspeed indication of zero while you are flying clearly shows something
> is wrong with your plane. It cannot be certified airworthy.
>
> It doesn't matter if you are in Finland or anywhere else. You cannot fly
> with an airspeed indicator that reads zero.
The indication returned as I descended out of the cloud and the
pitot heat did its job.
--
-TV
Tauno Voipio
Feb 12, 2021, 2:38:49 PM2/12/21
to
On 12.2.21 16.28, Peter wrote:
> which overwhelmed the heating.
>
> There are general aviation avionics which become completely useless if
> the pitot tube ices up. More recently they have been doing GPS backups
> for airdata, which is a good idea.
It seems that Steve does not believe what severe icing does.
It was a surprise that all five pitots on AF447 went out of service.
The crew still had useable speed information from the navigation
system, and the flight probably could have been salvaged if the crew
had kept thrust and attitude constant after the upset. The gyros
and engine instruments were fine.
In both cases when I have been in severe icing with an airplane
not certified for it, I handled the situation with the navigation
system information until out of the icing zone.
--
-TV
>
> Steve Wilson <sp...@me.com> wrote:
>
>> Pitot tubes for airspeed indicators are also subject to icing, which brought
>> down air France flight 447. They did not turn on the pitot heaters.
>
> They had pitot heat on, but the tubes got filled up with crystals
> Steve Wilson <sp...@me.com> wrote:
>
>> Pitot tubes for airspeed indicators are also subject to icing, which brought
>> down air France flight 447. They did not turn on the pitot heaters.
>
> which overwhelmed the heating.
>
> There are general aviation avionics which become completely useless if
> the pitot tube ices up. More recently they have been doing GPS backups
> for airdata, which is a good idea.
It seems that Steve does not believe what severe icing does.
It was a surprise that all five pitots on AF447 went out of service.
The crew still had useable speed information from the navigation
system, and the flight probably could have been salvaged if the crew
had kept thrust and attitude constant after the upset. The gyros
and engine instruments were fine.
In both cases when I have been in severe icing with an airplane
not certified for it, I handled the situation with the navigation
system information until out of the icing zone.
--
-TV
Tauno Voipio
Feb 12, 2021, 2:40:34 PM2/12/21
to
On 12.2.21 16.33, Peter wrote:
> gravity vector as a slow background process, so if you do "just the
> right kind of" flying for too long, you will fool it.
>
> AIs can be vacuum driven or electric. The reason for the vacuum ones
> is that it avoids having two alternators (and two batteries, etc) for
> IFR certification. You can nowadays remove the vacuum system and go
> fully electric, with the cert requirement being met by a backup
> battery in the instrument; usually 1hr or so, which I don't regard as
> an acceptable solution :) But I have a backup alternator... OTOH I
> also still have the vacuum AI.
>
> As I said, lots of work has gone into AHRS for navigation and nobody
> has got anywhere near. For attitude (pitch, roll, heading) yes, no
> problem, although you still need to feed a fluxgate (or some other mag
> field) sensor into the heading (Z axis yaw) gyro code - because long
> term accurate heading = viable solid state navigation :)
>
The turn indicator does not use the gravity reference. It just senses
the rotation velocity around the airplane's vertival axis.
--
-TV
>
> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>
>>> For redundancy, the turn rate indicator is usually electrically driven.
>>> Due to the limited movement of the gyro frame, it is pretty easy to
>>> feed electricity to the motor without needing brushes.
>>
>> That must get interesting in a snap roll. Maybe that's why Frank reset
>> things now and then.
>
> All these devices can be fooled - because they have to sense the
> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>
>>> For redundancy, the turn rate indicator is usually electrically driven.
>>> Due to the limited movement of the gyro frame, it is pretty easy to
>>> feed electricity to the motor without needing brushes.
>>
>> That must get interesting in a snap roll. Maybe that's why Frank reset
>> things now and then.
>
> gravity vector as a slow background process, so if you do "just the
> right kind of" flying for too long, you will fool it.
>
> AIs can be vacuum driven or electric. The reason for the vacuum ones
> is that it avoids having two alternators (and two batteries, etc) for
> IFR certification. You can nowadays remove the vacuum system and go
> fully electric, with the cert requirement being met by a backup
> battery in the instrument; usually 1hr or so, which I don't regard as
> an acceptable solution :) But I have a backup alternator... OTOH I
> also still have the vacuum AI.
>
> As I said, lots of work has gone into AHRS for navigation and nobody
> has got anywhere near. For attitude (pitch, roll, heading) yes, no
> problem, although you still need to feed a fluxgate (or some other mag
> field) sensor into the heading (Z axis yaw) gyro code - because long
> term accurate heading = viable solid state navigation :)
>
The turn indicator does not use the gravity reference. It just senses
the rotation velocity around the airplane's vertival axis.
--
-TV
Steve Wilson
Feb 12, 2021, 7:16:36 PM2/12/21
to
on several occasions that required activation of the boots, but nothing I
would categorize as severe.
You could have prevented considerable waste of time by stating icing was
the cause of your airspeed reading. It could also have been caused by
numerous other issues which would have resulted in grounding the plane
until they were fixed.
You stated
> It seems that you did not read my previous posts. It is exactly what
> I wrote.
Since you deliberately cause confusion by omitting relevant facts, and fail
to specify the reason for your objections, I don't see a reason for wasting
any more of my time with you.
Steve Wilson
Feb 12, 2021, 7:53:53 PM2/12/21
to
Tauno Voipio <tauno....@notused.fi.invalid> wrote:
> On 12.2.21 16.28, Peter wrote:
>>
>> Steve Wilson <sp...@me.com> wrote:
>>
>>> Pitot tubes for airspeed indicators are also subject to icing, which
>>> brought down air France flight 447. They did not turn on the pitot
>>> heaters.
>>
>> They had pitot heat on, but the tubes got filled up with crystals
>> which overwhelmed the heating.
>>
>> There are general aviation avionics which become completely useless if
>> the pitot tube ices up. More recently they have been doing GPS backups
>> for airdata, which is a good idea.
>
> It seems that Steve does not believe what severe icing does.
Don't be a jerk. Of course I know what severe icing is. I was in the RCAF
> On 12.2.21 16.28, Peter wrote:
>>
>> Steve Wilson <sp...@me.com> wrote:
>>
>>> Pitot tubes for airspeed indicators are also subject to icing, which
>>> brought down air France flight 447. They did not turn on the pitot
>>> heaters.
>>
>> They had pitot heat on, but the tubes got filled up with crystals
>> which overwhelmed the heating.
>>
>> There are general aviation avionics which become completely useless if
>> the pitot tube ices up. More recently they have been doing GPS backups
>> for airdata, which is a good idea.
>
> It seems that Steve does not believe what severe icing does.
and have flown in icing conditions you would not believe.
> It was a surprise that all five pitots on AF447 went out of service.
> The crew still had useable speed information from the navigation
> system, and the flight probably could have been salvaged if the crew
> had kept thrust and attitude constant after the upset. The gyros
> and engine instruments were fine.
Yet, as the New York Times points out, "Investigators found that the loss
of valid speed readings lasted for no more than a minute of the plane's
terrifying four-minute descent." Even if the air-speed data had been lost
entirely, the pilots could have saved the plane, BEA director Jean-Paul
Troadec told reporters.
https://www.pbs.org/wgbh/nova/insidenova/2011/07/air-france-flight-447-
could-have-been-saved.html
The big problem with Airbus is changing the flight characteristics when the
plane gets into trouble.
Quote:
There are four reconfiguration modes for the Airbus fly-by-wire aircraft:
alternate law 1, alternate law 2, direct law and mechanical law. The ground
mode and flare modes for alternate law are identical to those modes for
normal law.
https://en.wikipedia.org/wiki/Flight_control_modes
With full up elevator, the plane stalled, but the stall warning was turned
off when the airspeed was below a certain level. As soon as the pilot
relaxed the control and the airspeed increased, the stall warning blared
again until he returned to full up. Here is what happened:
Quote:
At 02:10:05 UTC, the autopilot disengaged, most likely due to hailstones
blocking the pitot tubes, and the aircraft transitioned from "normal law"
to "alternate law 2".[64]
The engines' auto-thrust systems disengaged three seconds later. As the
pilot flying, first officer Bonin took over control of the aircraft, using
the command language "I have the controls." Without the auto-pilot, the
aircraft started to roll to the right due to turbulence, and Bonin reacted
by deflecting his side-stick to the left. One consequence of the change to
alternate law was an increase in the aircraft's sensitivity to roll, and
the pilot's input over-corrected.
During the next 30 seconds, the aircraft rolled alternately left and right
as Bonin adjusted to the altered handling characteristics of the aircraft.
[65] At the same time he abruptly pulled back on his side-stick, raising
the nose. This action has been described as unnecessary and excessive under
the circumstances.[66]
The aircraft's stall warning briefly sounded twice due to the angle of
attack tolerance being exceeded, and the aircraft's indicated airspeed
dropped sharply from 274 knots (507 km/h; 315 mph) to 52 knots (96 km/h; 60
mph). The aircraft's angle of attack increased, and subsequently began to
climb above its cruising altitude of 35,000 ft (FL350). During this ascent,
the aircraft attained vertical speeds well in excess of the typical rate of
climb for the Airbus A330, which usually ascend at rates no greater than
2000 feet per minute (10.16 m/s). The aircraft experienced a peak vertical
speed close to 7,000 feet per minute (36 m/s; 130 km/h),[65] which occurred
as first officer Bonin brought the rolling movements under control.
At 02:10:34 UTC, after displaying incorrectly for half a minute, the left-
side instruments recorded a sharp rise in airspeed to 223 knots (413 km/h;
257 mph), as did the Integrated Standby Instrument System (ISIS) 33 seconds
later.[67] The right-side instruments were not recorded by the recorder.
The icing event had lasted for just over a minute,[68][69][2]:198[70] yet
first officer Bonin continued to make nose-up inputs. The trimmable
horizontal stabilizer (THS) moved from three to 13 degrees nose-up in about
one minute, and remained in the latter position until the end of the
flight.
At 02:11:10 UTC, the aircraft had climbed to its maximum altitude of around
38,000 feet (12,000 m). At this point, the aircraft's angle of attack was
16 degrees, and the engine thrust levers were in the fully forward
takeoff/go-around detent (TOGA). As the aircraft began to descend, the
angle of attack rapidly increased toward 30 degrees.
A second consequence of the reconfiguration into alternate law was that the
stall protection no longer operated, whereas in normal law the aircraft's
flight management computers would have acted to prevent such a high angle
of attack.[71] The wings lost lift and the aircraft began to stall.[3]
Confused, first officer Bonin exclaimed "[Expletive] I don't have control
of the airplane any more now", and two seconds later, "I don't have control
of the airplane at all!"[28] First officer Robert responded to this by
saying, "controls to the left", and took over control of the aircraft.[72]
[31] Robert pushed his side-stick forward to lower the nose and recover
from the stall; however, Bonin was still pulling his side-stick back. The
inputs cancelled each other out and triggered an aural "dual input"
warning.
At 02:11:40 UTC, captain Dubois re-entered the cockpit after being summoned
by first officer Robert. Noticing the various alarms going off, he asked
the two crew members, "er what are you (doing)?"[31] The angle of attack
had then reached 40 degrees, and the aircraft had descended to 35,000 feet
(11,000 m) with the engines running at almost 100% N1 (the rotational speed
of the front intake fan, which delivers most of a turbofan engine's
thrust). The stall warnings stopped, as all airspeed indications were now
considered invalid by the aircraft's computer due to the high angle of
attack.[73] The aircraft had its nose above the horizon but was descending
steeply.
Roughly 20 seconds later, at 02:12 UTC, Bonin decreased the aircraft's
pitch slightly. Airspeed indications became valid, and the stall warning
sounded again; it then sounded intermittently for the remaining duration of
the flight, stopping only when the pilots increased the aircraft's nose-up
pitch. From there until the end of the flight, the angle of attack never
dropped below 35 degrees. From the time the aircraft stalled until its
impact into the ocean, the engines were primarily developing either 100
percent N1 or TOGA thrust, though they were briefly spooled down to about
50 percent N1 on two occasions. The engines always responded to commands
and were developing in excess of 100 percent N1 when the flight ended.
First officer Robert responded to captain Dubois by saying: "We've lost all
control of the aeroplane, we don’t understand anything, we’ve tried
everything".[31] Soon after this, Robert said to himself, "climb" four
consecutive times. Bonin heard this and replied, "But I've been at maximum
nose-up for a while!" When Captain Dubois heard this, he realized Bonin was
causing the stall, and shouted, "No no no, don't climb! No No No!"[74][31]
When first officer Robert heard this, he told Bonin to give the control of
the airplane to him.[2] In response to this, Bonin temporarily gave the
controls to Robert.[31][74][2] Robert pushed his side stick forward to try
to regain lift for the airplane to climb out of the stall. However, the
aircraft was too low to recover from the stall. Shortly thereafter, the
ground proximity warning system sounded an alarm, warning the crew about
the aircraft's imminent crash with the ocean. In response, Bonin (without
informing his colleagues) pulled his side stick all the way back again,[31]
[2] and said, "[Expletive] We're going to crash! This can't be true. But
what's happening?"[74][31][2][75][28] The last recording on the CVR was
captain Dubois saying: "(ten) degrees pitch attitude."
https://en.wikipedia.org/wiki/Air_France_Flight_447
So the design of the aircraft caused the crash.
> In both cases when I have been in severe icing with an airplane
> not certified for it, I handled the situation with the navigation
> system information until out of the icing zone.
Steve Wilson
Feb 19, 2021, 5:00:16 PM2/19/21
to
Steve Wilson <sp...@me.com> wrote:
[...]
[...]
Update: Captain Chesley Sullenberger, hero of "Miracle on the Hudson",
shows how the copilot pulled the sidestick back and crashed the plane.
The sidesticks in the Airbus are not coupled together, so the pilot had no
idea what the copilot was doing.
He also shows the same action would be difficult to conceal in a Boeing
since the yokes are mechanically coupled together.
https://www.youtube.com/watch?v=kERSSRJant0
--
The best designs occur in the theta state. - sw
[...]
Update: Captain Chesley Sullenberger, hero of "Miracle on the Hudson",
shows how the copilot pulled the sidestick back and crashed the plane.
The sidesticks in the Airbus are not coupled together, so the pilot had no
idea what the copilot was doing.
He also shows the same action would be difficult to conceal in a Boeing
since the yokes are mechanically coupled together.
https://www.youtube.com/watch?v=kERSSRJant0
--
The best designs occur in the theta state. - sw
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