Homebuilt stall warning?
Matthew Long & Agnès Peillet
for use on a homebuilt? I know one could be salvaged from a factory
built, and there are lots of tempting comical answers, but I'm actually
looking for some sketches or plans. I'm thinking of more that, say, an
angle of attack vane, something with both visual and audible (buzzer)
warning.
TIA,
Matthew
--
Matthew Long & Agnès Peillet
Jamaica Plain, Massachusetts, USA
owln...@gis.net
AIRPLANEIT
bit on the Bacon Saver. It's the exact thing you're looking for, Angle of
Attack vane. I'm sure it could easily be set up for a microswitch to set off an
audible warning.
The AOA indicator has also been the talk in the thread "What instruments
required for day/night VFR"
-Nick Stolley
PA-18-90 Super Cub
Woodbury, MN
GuyGratton
In article <364D27EE...@gis.net>, Matthew Long & =?iso-8859-1?Q?Agn=E8s?=
Peillet <owln...@gis.net> writes:
>Anyone know of any designs for simple, effective, stall warning devices
>for use on a homebuilt?
If the stall warning is really that bad, the best and easiest may be triangular
strips (often called "Toblerone Strips") on the inboard leading edge of the
wing. This should cause buffet through the stick through turbulence hitting
the elevator as the stall is approached. Also tends to stop it stalling too
violently. BUT do this with great care, you can end up badly effecting the
handling qualities if you're not careful.
Matthew Long & Agnès Peillet
AIRPLANEIT wrote:
--
jkahn
>
> Anyone know of any designs for simple, effective, stall warning devices
> built, and there are lots of tempting comical answers, but I'm actually
> looking for some sketches or plans. I'm thinking of more that, say, an
> angle of attack vane, something with both visual and audible (buzzer)
> warning.
>
> TIA,
> Matthew
>
> --
You can make an AOA indicator using an airspeed indicator. The pitot
and static sides of the airspeed indicatior are connected to
upper and lower chambers of a tube that is installed laterally
in the airstream. A plate separates the upper and lower chambers.
A row of holes are drilled at the 2 and 4 o'clock positions (in
cross section), 3 o'clock being the direction of flight, one row
into the upper chamber and one row into the lower chamber. As
angle of attack increases the lower row of holes gets a more direct
blast of air as the upper row gets a less direct blast, creating
a pressure differential the registers as an airspeed indication.
You cover the number markings on the airspeed face and paint on
markings to denote stalling aoa by flight testing.
This was in a Sport Aviation years back... can't say myself how
well it works... be fun to try though...
John Kahn
AIRPLANEIT
>well it works... be fun to try though...
Heard it works great...best with a low speed ASI, like off a cub or ultralight.
Fred Huber
effective, but the concept has a problem.
Airspeed indicators work on differential pressure from static (the basically
non-moving air such as found in an enclosed cockpit that is not pressurized)
and the dynamically pressurized air sensed by the pitot tube. The pitot
tube is set up to have the air that is being entered by the aircraft enter a
hole and cause a pressurization of the airspeed indicator. The static side
is arranged such as to be able to equalize pressure with the air surrounding
the aircraft, and not be affected by most normal flight conditions. The
differential pressure is a fairly accurate method of indicating airspeed,
but does have a correction factor for altitude. Thus you will see IAS
(Indicated Air Speed) and TAS True Air Speed) reported in aviation magazine
articles. Most airspeed indicators used in homebuilts do not have the
altitude correction built in. but for less than 10,000 ft the correction
will be less than 5 kts for speeds under 150 kts.
Given a standard wing loading and straight/level flight the stall speed of
any aircraft is very predictable and stall warning can be derived directly
from IAS. When you bank, maneuver or increase payload/fuel load, the IAS
based stall warning will occur AFTER the stall.
The best defense against stalls is maintaining airspeed and avoiding extreme
maneuvers Indicators and warning devices which will ALWAYS tell when you
are approaching a stall do not exist, you can stall at VNE (Velocity: Never
Exceed ) under extreme conditions.
FHH
jkahn <jk...@mail2.planeteer.com> wrote in message
news:364E67...@mail2.planeteer.com...
>This was in a Sport Aviation years back... can't say myself how
>well it works... be fun to try though...
>
>
>John Kahn
Richard Lamb
I can't get my parasol to break at anlthing less than agressively
accellerated manouvers. It will sink like the Titanic if you let
it get slow enough, but no actual stall.
Report in by type?
Barry Herbert
like a rock. At half throttle it'll break at 35mph indicated, 3/4 to full
throttle it just climbs.
The nice thing too is that in this one there is no tendency for the wings to
drop.
Richard Lamb <lam...@flash.net> wrote in message
news:364EA56A...@flash.net...
jkahn
I'm not sure if what you are describing is what I was describing.
In the design I saw, the two chambers that are plumbed to the
pitot and static sides of the airspeed indicator are intended to
only create a pressure differential (and hence airspeed indication)
if the lateral tube facing into wind is rotated to make one set of
holes see a more direct blast of air than the other. With both
sets of holes at 2 and 4 o'clock, the relative airflow is the same
and there is no differential and the airspeed indication is zero. As
AOA is increased the upper set of holes (connected to the static
side) sees declining ram pressure, while the lower set of holes
sees a increase in ram pressure. Within a limited range, (it only
has to operate through 15 degrees or so) this pressure differential
would be constant even though airspeed varies.
At any rate what you are supposed to see is zero airspeed indication
with the AOA at zero. The indication wouln't change with actual
airspeed, since the ram pressure to each chamber remains equal.
When the lateral tube rotates and starts to move the upper holes
out of the wind and the lower holes into the wind is when the
airspeed indication shows, which in the first 20 degrees
of movement is supposed to vary in proportion to AOA, not airspeed,
and which can be calibrated as such.
Anyway, that's the theory as I remembered it. I can't say if it
actually works.
JKahn
GuyGratton
In article <364EA56A...@flash.net>, Richard Lamb <lam...@flash.net>
writes:
>
>While we're on the subject, does your UL actually stall?
>I can't get my parasol to break at anlthing less than agressively
>accellerated manouvers. It will sink like the Titanic if you let
>it get slow enough, but no actual stall.
>
When I went through Test Pilots School (who knew a few things about stalling) a
stall was defined as when full control of the aircraft was lost - the fine
definition was left to the assessing pilot. If (say) I am flying a Spectrum (3
axis tandem microlight) , I would define stall as full back stick, and a
descent - I cannot pitch up or climb, therefore full control is lost, therefore
the aircraft is stalled. When I fly my Raven (high performance trike), I
define stall as a sharp pitch break downwards, it was undemanded therefore I
did not have full control.
I get upset when people say an aircraft cannot stall - it is (in my experience)
never true. It may be true that an aircraft does not have the textbook pitch
break.
BCAR Section S (the British airworthiness standard for microlights) says the
following...
"... a stall results as evidenced by a downward pitching motion or downward
pitching and rolling motion not immediately controllable or until the
longitudinal control reaches the stop". (from para S201(a))
Not exactly the definition I'd use, but pretty similar.
2
G
Guy Gratton
Richard Lamb
here.
I've always considered the stall as the Brits below...
nose down pitching motion - not correctable without gaining speed...
(I'll leave the nose UP pitching moment to the REAL test pilots ;)
At 25-30 MPH _INDICATED_ on my plane, I'm decending like the Space
Shuttle
- BUT -
I still have rudder, aileron, and yes - even PITCH control.
It just doesn't have enough lift to stay up.
(Now - mind you - I don't _even_ consider this as a substitute for a
cross controlled slip at low altitudes as it would leave me with
no energy to use for a flair.)
If you have your Spectrum in the described condition (full aft stick
and decending) and add power, what happens?
Me thinks it will simply level off or climb.
If that's the case, I think it would be hard to call it a stall.
And, bottom line, I think I prefer this to an "unstallable" airplane
like the Ercoupe - which is based on limiting the pitch authority
avalible to the pilot.
j...@ix.netcom.com
and altitudes, why does the Navy use a vane-type AOA indicator on their fighter
aircraft? (ref. Dec98 Kitplanes). I suspect that at higher altitudes, the
absolute pressure difference between the two will get less and less, so in
effect you have an "IAOA" (indicated AOA) rather than "TAOA". Do you know if
the Sportplanes article addressed that question?
-john r.
D.N.
stall warning device. It was tested on his prototype Ranger.
There was an article on the Sherwood Ranger in Kitplanes a couple of years
ago, and the author Miles McCallum praised how well the stall warner
worked. I have heard that Miles might try to market the product for the
designer Russ Light.
You can e-mail the designer at : ru...@tigercub.force9.co.uk
Miles McCallum's address is : mil...@avnet.co.uk
If these addresses don't work, try mailing to the designer at:
TCD Ltd.
Larkfield,Retford Road
Mattersey, Doncaster
South Yorkshier DN10 5HG
attn: Russ Light
Matthew Long & Agnès Peillet <owln...@gis.net> wrote in article
<364D27EE...@gis.net>...
> Anyone know of any designs for simple, effective, stall warning devices
> for use on a homebuilt? I know one could be salvaged from a factory
> built, and there are lots of tempting comical answers, but I'm actually
> looking for some sketches or plans. I'm thinking of more that, say, an
> angle of attack vane, something with both visual and audible (buzzer)
> warning.
>
> TIA,
> Matthew
>
> --
> Matthew Long & Agnès Peillet
Jonathan Davis
>
> Sounds like a very interesting idea, but if it does work reliably at all speeds
> and altitudes, why does the Navy use a vane-type AOA indicator on their fighter
> aircraft? (ref. Dec98 Kitplanes).
I came across this at http://www.monmouth.com/~jsd/how/htm/airfoils.html
"The second type of stall-warning device (used on Cessna 152, 172, etc.)
operates on a different principle. It is sensitive to suction at the
surface
rather than flow along the surface. It is positioned just below the
leading edge of the wing, as indicated in the right panel of figure 3.9.
At low
angles of attack, the leading edge is a low-velocity, high-pressure
region; at high angles of attack it becomes a high-velocity,
low-pressure
region. When the low-pressure region extends far enough down around the
leading edge, it will suck air out of the opening. The air flows through
a harmonica reed, producing an audible warning.
Figure 3.9 - Stall Warning
Devices
Note that neither device actually detects the stall. Each one really
just measures angle of attack. It is designed to give you a warning a
few
degrees before the wing reaches the angle of attack where the stall is
expected. Of course if there is something wrong, such as frost on the
wing (see section 3.13), the wing will stall at a lower-than-expected
angle of attack, and you will get no warning from the so-called stall
warning
device."
Something to think about
Jon Davis
dgla...@earthlink.net
> You can make an AOA indicator using an airspeed indicator. The pitot
> and static sides of the airspeed indicatior are connected to
> upper and lower chambers of a tube that is installed laterally
> in the airstream. A plate separates the upper and lower chambers.
> A row of holes are drilled at the 2 and 4 o'clock positions (in
> cross section), 3 o'clock being the direction of flight, one row
> into the upper chamber and one row into the lower chamber. As
> angle of attack increases the lower row of holes gets a more direct
> blast of air as the upper row gets a less direct blast, creating
> a pressure differential the registers as an airspeed indication.
>
> You cover the number markings on the airspeed face and paint on
> markings to denote stalling aoa by flight testing.
This is approximately how the lift Reserve Indicator works. There are two ports on
90-degree adjacent faces of a vane that mounts below the wing. The dial indicates
relative pressure differential between the two.
Rob
>
> Sounds like a very interesting idea, but if it does work reliably at all speeds
> and altitudes, why does the Navy use a vane-type AOA indicator on their fighter
> aircraft?
On the Air Force F-111's that I worked on they had cone shaped AOA
probes on the forward right side of the aircraft that had two slots in
them. It would rotate with the angle of attack. It was also heated.
... Rob
Bob U.
>
>I get upset when people say an aircraft cannot stall - it is (in my experience)
>never true. It may be true that an aircraft does not have the textbook pitch
>break.
>Guy Gratton
++++++++++++++++++++++++++++++++++++++++++++++++
Ah shit.
There goes the Ercoupe neighborhood.
Bob U.
Fred Huber
A normal aircraft can stall in such a manner that it doesn't have that
elevator-drop feel. If the wing is big enough and the plane is light
enough.
The test for stall is where does the elevator fail to keep the nose up.
(conventional planes, and canards) In a conventional plane the elevator
quits flying after the main wing, in the canards the canard surface quits
flying before the main wing, both situations produce a nose-down effect. (if
the wrong surface stalls first you get in BIG trouble.)
Many slow flying aircraft will drop their nose gently, and resume flight on
their own, almost unnoticed if they are trimmed slightly nose heavy. (A VERY
safe setup) You never feel the gentle version of the stall, but you can see
it if you closely watch an artificial horizon. To try this get in a Piper
Cub that has the artificial horizon (some didn't originally)get it flying
level and slow, then add a very minor amount of up-elevator. If you were
flying right at stall speed you will be able to watch the artificial horizon
cycle up and down as the plane stalls and recovers itself. Do it right and
you won't feel the stall.
Richard Lamb <lam...@flash.net> wrote in message
news:364EA56A...@flash.net...
>While we're on the subject, does your UL actually stall?
>I can't get my parasol to break at anlthing less than agressively
>accellerated manouvers. It will sink like the Titanic if you let
>it get slow enough, but no actual stall.
>
>Report in by type?
Fred Huber
warning device.
The only questions at this point are dependant on the aircraft you are
installing it in..... Where on the leading edge do you put the sensing
hole?.... Probably not far back. How big a hole, and how do you plumb it to
an appropriate noisemaker?
Experimentation seems to be the answer at this point.
Jonathan Davis <jond...@dmv.com> wrote in message
news:365057...@dmv.com...
>j...@ix.netcom.com wrote:
>>
>> Sounds like a very interesting idea, but if it does work reliably at all
speeds
>> and altitudes, why does the Navy use a vane-type AOA indicator on their
fighter
jkahn
>
> j...@ix.netcom.com wrote:
> >
> > Sounds like a very interesting idea, but if it does work reliably at all speeds
> > and altitudes, why does the Navy use a vane-type AOA indicator on their fighter
> > aircraft?
>
> probes on the forward right side of the aircraft that had two slots in
> them. It would rotate with the angle of attack. It was also heated.
>
> ... Rob
The idea of the airspeed indicator as AOA indicator is for people
with no electrical systems.
If my airplane has an electrical system I would simply cobble up
an AOA indicator using a vane mounted on a pot out on the pitot
probe, that would be wired into a voltmeter on the panel
with the face calibrated for AOA.
john
mark....@sciatl.com
It is a differential pressure switch. ~$50, not too outrageous, and is
adjustable for the pressure at which it switches.
What I was thinking of was an LRI type AOA guage with one of these plumbed in
as well. That way you could add an idiot light and buzzer to get your
attention.
In article <72p5mq$sc2$2...@supernews.com>,
"Fred Huber" <fhu...@truserve.com> wrote:
> This just gave the description for how to build your homebuilt's stall
> warning device.
>
> The only questions at this point are dependant on the aircraft you are
> installing it in..... Where on the leading edge do you put the sensing
> hole?.... Probably not far back. How big a hole, and how do you plumb it to
> an appropriate noisemaker?
>
> Experimentation seems to be the answer at this point.
>
> Jonathan Davis <jond...@dmv.com> wrote in message
> news:365057...@dmv.com...
> >j...@ix.netcom.com wrote:
> >>
> >> Sounds like a very interesting idea, but if it does work reliably at all
> speeds
> >> and altitudes, why does the Navy use a vane-type AOA indicator on their
> fighter
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Daniel Grunloh
Richard Lamb <lam...@flash.net> wrote:
>While we're on the subject, does your UL actually stall?
>I can't get my parasol to break at anlthing less than agressively
>accellerated manouvers. It will sink like the Titanic if you let
>it get slow enough, but no actual stall.
>
>Report in by type?
I have two ultralights and neither one will stall.
My Sky Pup has the same airfoil as the Ercoupe. It only
mushes and will not give a stall break. It's behaviour
in pitch is the same as the 'Coupe. If you reduce power
with the stick all the way back the nose drops but not as
much as expected in relation to the steepening glide angle.
My Air Creation Funracer trike also will not stall even if
the control bar is held to the full nose-up postion.
I believe both of these craft are in effect elevator limited.
If the CG is too far aft or the control system is altered,
they will stall just like anything else. I believe the
EAGLE XL ultralight and other canard craft are similar.
Sure I can chop the throttle in a steep climb and get a nose
drop, but nothing like some planes will give you out of level
flight (with minimal warning).
Next you may want to argue about what IS a stall. I don't care.
I can only say that my ultraights are safe without a stall horn
or a working airpeed indicator. I like it that way.
--Dan
--------------
Daniel Grunloh (gru...@uiuc.edu)
http://www.staff.uiuc.edu/~grunloh
Daniel Grunloh
"Fred Huber" <fhu...@truserve.com> wrote:
>Many slow flying aircraft will drop their nose gently, and resume
flight on
>their own, almost unnoticed if they are trimmed slightly nose heavy.
(A VERY
>safe setup) You never feel the gentle version of the stall, but you
can see
>it if you closely watch an artificial horizon.
Thanks I sure that is right.
Also it's fair to say that no specialized warning equipment
should be needed on those craft where the stall cannot even be
noticed or felt without special instruments.
W.H.Nester
Charlie <x...@newsguy.com> wrote in article
<36507330....@enews.newsguy.com>...
> ..........You're not trying hard enough Dan. :-) Pull the bar all the
> way in. Wait a few seconds. Swiftly push the bar out to the
> front strut.
>
> Charlie
>
Thanks. I tried this maneuver and my wings folded! Now what do I do? Pull
the chute??? A quick reply will be much appreciated.
Bill
Seriously, I know your describing an acceleration stall where centifugal
force loads the wing in excess of the weight. A word of caution might be in
order, however.
Daniel Grunloh
x...@newsguy.com (Charlie) wrote:
>On Mon, 16 Nov 98 18:07:37 GMT, gru...@uiuc.edu (Daniel
>Grunloh) wrote:
>>My Air Creation Funracer trike also will not stall even if
>>the control bar is held to the full nose-up postion.
>
>way in. Wait a few seconds. Swiftly push the bar out to the
>front strut.
Of course that works. Woopeeeee!
I was referring to the typical one knot per second speed reduction
from stabilized flight. Most curious however is that at first I
thought it would not fly as slow as advertised. I pushed the bar all
the way out, it slowed down to 30-32 or so and that was it. It should
slow to around 25 mph.
I turned out I wasn't waiting long enough. The GPS and ASI indicated
the speed slowly decayed to the lower range if I just held it there
long enough and waited. Faint nibbles, but no stall unless I drop
the power suddenly and then only about 15 degrees down, bar still out
all the way. I honestly haven't yet tried yet to do stalls in turns.
Too busy having fun.
I HAVE simulated full power loss from a max climb angle condition
to familiarize myself with that possibility. Nothing too scary but
a quite sudden loss of "UP".
P.S. For non trikers out there, the stall recovery in trikes is a
little different than fixed wings. You must let the trike rotate
downward on it's own at the break keeping the bar out, then bringing
it back in to normal position. If you pull nose down too sudden and
too soon, the combined rotation (no tail) can be excessive and you may
end up REALLY straight down or even inverted. Could be very bad.
--Dan
Richard Lamb
Now, let's hear from the rest of you guys
(and, of course, ladies....)
I know it's not an ultralight (unless you are a news reporter)
Anybody familiar with advanced stalls in the Piper Cherokee?
Neat ride!
W.H.Nester
Daniel Grunloh <gru...@uiuc.edu> wrote in article
<72q7nh$1a1$1...@vixen.cso.uiuc.edu>...
..................
> P.S. For non trikers out there, the stall recovery in trikes is a
> little different than fixed wings. You must let the trike rotate
> downward on it's own at the break keeping the bar out, then bringing
> it back in to normal position. If you pull nose down too sudden and
> too soon, the combined rotation (no tail) can be excessive and you may
> end up REALLY straight down or even inverted. Could be very bad.
>
> --Dan
>
>
> --------------
> Daniel Grunloh (gru...@uiuc.edu)
> http://www.staff.uiuc.edu/~grunloh
>
Also, most aircraft wings stall at the root section first and at the wing
tips last, but the effect is quite exaggerated on the flex-wing trikes.
This effect also partially explains why the stall break in a trike is less
pronounced than in a fixed wing aircraft, It would therefore seem that a
stall warning device would be less useful for a trike, since the gradual
onset of a stall in most trike designs is itself a stall warning. (I don't
know what the stall characteristics are for some of the more advanced trike
wing designs; e.g., the "topless" ones and maybe some of the tighter rigged
double surface wings.)
Regards, Bill N.
brian whatcott
On Mon, 16 Nov 1998 11:49:46 -0500, Jonathan Davis,jond...@dmv.com
says...
>Note that neither device actually detects the stall. Each one really
>just measures angle of attack. It is designed to give you a warning a
>few
>degrees before the wing reaches the angle of attack where the stall is
>expected. Of course if there is something wrong, such as frost on the
>wing (see section 3.13), the wing will stall at a lower-than-expected
>angle of attack, and you will get no warning from the so-called stall
>warning
>device."
>
>Something to think about
>
>Jon Davis
It was two or three years ago. The stench wasn't at all bad at that point.
A German PhD candidate wrote in about his thesis: a stall warning device.
He worked for Daimler-Benz. I wrote for more details.
He used a port well back along the upper surface and (if I recall)
the regular static port , or something similar.
His motivation was to detect impending stall by sensing the disturbed
airflow well back. Sounded interesting. More reliable with frosty wings too,
I'd think...
Brian Whatcott Altus OK
Charles K. Scott
> On Mon, 16 Nov 1998 11:49:46 -0500, Jonathan Davis,jond...@dmv.com
> says...
> >Note that neither device actually detects the stall. Each one really
> >just measures angle of attack. It is designed to give you a warning a
> >few
> >degrees before the wing reaches the angle of attack where the stall is
> >expected. Of course if there is something wrong, such as frost on the
> >wing (see section 3.13), the wing will stall at a lower-than-expected
> >angle of attack, and you will get no warning from the so-called stall
> >warning
> >device."
> >
> >Something to think about
> >
> >Jon Davis
Burt Rutan has suggested a stall warning device that I believe he's
tested. It's a pitot tube mounted on top of the wing back by the
aileron. This is a lot smarter than it sounds. He actually proposed
it as a pitot location that would be snow, rain and ice free.
The height of the tube was crucial because it had to be mounted high
enough to sample airflow but low enough to stay out of the way of rain
being slung off the top of the airfoil. This was why he said it would
be free of ice. The force of airflow over the wing keeps ice off the
back part of the wing. If it's going to deposit, it does so on the
leading part of the wing. In pure rain, the airflow forces the water
particles up over the wing and it doesn't have a chance to dip low
enough to get into the pitot tube, if located at proper spot and
height.
Here's the added bonus. When the wing nears stall, the airflow trips
to turbulent and the air speed indicator stops reading. A VERY clear
indication of a stall. Pretty clever thinking.
I haven't heard any more about it since I read this several years ago.
Corky Scott
Charles K. Scott
"W.H.Nester" <wne...@scctel.com> writes:
> Also, most aircraft wings stall at the root section first and at the wing
> tips last, but the effect is quite exaggerated on the flex-wing trikes.
> This effect also partially explains why the stall break in a trike is less
> pronounced than in a fixed wing aircraft, It would therefore seem that a
> stall warning device would be less useful for a trike, since the gradual
> onset of a stall in most trike designs is itself a stall warning. (I don't
> know what the stall characteristics are for some of the more advanced trike
> wing designs; e.g., the "topless" ones and maybe some of the tighter rigged
> double surface wings.)
>
> Regards, Bill N.
It sounds like it should be pretty easy for trike owners to make
themselves a "windvane" type AOA indicator. These are really simple
devices that are plates pivoted with a slight bias towards the front
(so there is more hanging off the back than the front, just like any
windvane) and mounted horizontally rather than vertically. At flight
speed it streams to the rear. You just mount it to a backing plate and
mark graduations on the backing plate and then do a series of stalls
watching the indicator. At the angle where flight is not possible
anymore, you mark a nice big RED line. Then, while in flight, don't go
there.
Corky Scott
Daniel Grunloh
"W.H.Nester" <wne...@scctel.com> wrote:
>Also, most aircraft wings stall at the root section first and at the
>wing tips last, but the effect is quite exaggerated on the flex-wing
>trikes. This effect also partially explains why the stall break in a
>trike is less pronounced than in a fixed wing aircraft, It would
>therefore seem that a stall warning device would be less useful for a
>trike, since the gradual onset of a stall in most trike designs is
>itself a stall warning.
I might add that trikes in general have higher pitch control forces
and more travel than many fixed wings. It seems almost impossible to
accidentally or inadvertantly stall most trikes. It takes both arms
pushing all the way forward as far as you can reach, while leaning
forward in the seat! The vast majority are flown without even an ASI
because control bar pressure and the force of the relative wind on the
pilot are both nearly fool proof indicators.
Barry Herbert
I mean it's not like we fly uls in conditions that we loss sight of the
horizon, so visually we would know in advance if a stall condition was in
the making, wouldn't we?
In adverse weather conditions, where we shouldn't be in the first place, it
might be handy.
Barry
Charlie <x...@newsguy.com> wrote in message
news:36549403....@enews.newsguy.com...
>On 17 Nov 1998 13:35:23 GMT,
>Charles.K.Scott@**NOSPAM**.dartmouth.edu (Charles K. Scott)
>wrote:
>
>>It sounds like it should be pretty easy for trike owners to make
>>themselves a "windvane" type AOA indicator. These are really simple
>>devices that are plates pivoted with a slight bias towards the front
>>(so there is more hanging off the back than the front, just like any
>>windvane) and mounted horizontally rather than vertically. At flight
>>speed it streams to the rear. You just mount it to a backing plate and
>>mark graduations on the backing plate and then do a series of stalls
>>watching the indicator. At the angle where flight is not possible
>>anymore, you mark a nice big RED line. Then, while in flight, don't go
>>there.
>
>A stall warning would be a nice gimmick on a trike but be of
>very little practical use. When you stall a trike you have
>to be trying to stall it. It's not something that will sneak
>up on the pilot when they least expect it.
>
>Charlie
Fred Huber
possible on well trimmed stable aircraft. Any aircraft can be put in a
stall condition that can result in a spin. (except paraplanes) Some
aircraft are harder to put in that condition, and you almost have to try for
it. (Ercoupe {SP?}) but even with the spinproof sticker in the Ercoupe, I've
seen one put in a spin purposefully. A stall warning device is never
useless.
Daniel Grunloh <gru...@uiuc.edu> wrote in message
news:72poug$p6k$1...@vixen.cso.uiuc.edu...
>In article <72p5mm$sc2$1...@supernews.com>,
> "Fred Huber" <fhu...@truserve.com> wrote:
>
>>Many slow flying aircraft will drop their nose gently, and resume
>flight on
>>their own, almost unnoticed if they are trimmed slightly nose heavy.
>(A VERY
>>safe setup) You never feel the gentle version of the stall, but you
>can see
>>it if you closely watch an artificial horizon.
>
>
>Thanks I sure that is right.
>
>Also it's fair to say that no specialized warning equipment
>should be needed on those craft where the stall cannot even be
>noticed or felt without special instruments.
>
>-Dan
>
>
Bob U.
wrote:
>The gentle version of the stall is NOT guaranteed on ANY aircraft, just
>possible on well trimmed stable aircraft. Any aircraft can be put in a
>stall condition that can result in a spin. (except paraplanes) Some
>aircraft are harder to put in that condition, and you almost have to try for
>it. (Ercoupe {SP?}) but even with the spinproof sticker in the Ercoupe, I've
>seen one put in a spin purposefully. A stall warning device is never
>useless.
>
>FHH
>fhu...@truserve.com
+++++++++++++++++++++++++++++++++++++++++++++++++++
How about the FULL details of the Ercoupe you SAW spin?
How was it made to spin.
What was your vantage point to assure this was so?
How did it recover, if it did?
Since I own and fly an original Ercoupe (no rudder pedals) rigged
properly and flown within CG, your information might just save my life
and every other Couper someday......
I'm sure the FAA will be very interested too.
Bob - Ercoupe - U.
Daniel Grunloh
"Fred Huber" <fhu...@truserve.com> wrote:
>The gentle version of the stall is NOT guaranteed on ANY aircraft,
just
>possible on well trimmed stable aircraft. Any aircraft can be put in
>a stall condition that can result in a spin. (except paraplanes)
>Some aircraft are harder to put in that condition, and you almost
>have to try for it. (Ercoupe {SP?}) but even with the spinproof
>sticker in the Ercoupe, I've seen one put in a spin purposefully. A
>stall warning device is never useless.
I can't believe you would say that if you had some real time flown in
any of the various craft which are very very difficult to stall.
A drink cup holder would be more useful. :-)
Sorry, it's not personal, I just couldn't resist.
To repeat, the "gentler" version of the stall _IS_ gauranteed on any
Sky Pup or Ercoupe which has not had it's CG or control system
altered. It's not just the elevator either. It's the NACA 430
series airfoil with it's very low pitching moment, and other features.
At the other extreme there are other sport planes out there with
sharp leading edges, no inherent stall warning, bad stick feel
or no feedback due to friction, poor speed keeping, and large
changes of pitch due to high or low thrustline. They will try
to kill you if you don't pay close attention. By all means
such craft should be flown with the help of every available
warning device.
P.S. I suspect it would be VERY hard to spin an Ercoupe any more
than half a turn with only 2-axis controls.
highflyer
>
> P.S. For non trikers out there, the stall recovery in trikes is a
> little different than fixed wings. You must let the trike rotate
> downward on it's own at the break keeping the bar out, then bringing
> it back in to normal position. If you pull nose down too sudden and
> too soon, the combined rotation (no tail) can be excessive and you may
> end up REALLY straight down or even inverted. Could be very bad.
>
> --Dan
>
Tell me about it Dan! My first flight in a powered ultralight was in
an underpowered Easy Riser. It was a west bend engine with one of
Chuck's original reduction units.
I was rolling on the runway and the darn thing wasn't flying at all.
Finally I decided that my 200++ pound weight was holding the AOA
down so it wouldn't fly. I decided to "rotate" to see if it would
unstick. I pushed on the foot pegs and eased my weight all the way
back. suddenly it DID "unstick" and it immediately rotated to a
VERY steep climb angle. When it did, my feet fell off the pegs and
my legs dangled down beneath me.
This combined weight shift created a climb angle of about 90 degrees.
I was dangling by my pits and couldn't lift by overweight and under
muscled body high enough and far enough forward to get the CG back
within limits. Of course, with a vertical climb, my airspeed was
rapidly decaying. I made an altitude of about fifty or sixty feet
before the airspeed decayed to zero. I couldn't even bend over to
kiss myself goodbye in the traditional manner.
Then I realized that I was totally stalled, zero airspeed, I was
about to start back DOWN. I just grabbed the lower front spar, which
was up in front of my nose, with both hands and yanked it down around
my knees. When I did I sort of remained "fixed in space" while the
wing rotated 180 degrees and put the leading edges pointed straight
down.
Needless to say, as I descended, the airspeed built rapidly. I took
advantage of teh vertical descent to put my feet back onto the pegs.
When the ground got so close I couldn't stand it any longer I pushed
my feet out and did another max effort rotation. That little Easy
Riser just leveled out neatly about two inchs off the runway. I
quietly cut the throttle and LANDED. As I turned off the runway
I met an ambulance coming out to pick me up! My buddy saw my take
off and immediately ran to the meat wagon!
I sold the Easy Riser the next day.
HF
highflyer
>
> That's all very true, so what would be the point of a stall warning device?
> I mean it's not like we fly uls in conditions that we loss sight of the
> horizon, so visually we would know in advance if a stall condition was in
> the making, wouldn't we?
>
No not necessarily. The horizon has nothing to do with the wing
reaching a stall angle of attack. Any airplane that can stall at all
can usually stall at any attitude or speed where the stall will occur
before the wings come off.
The reason it is easy to avoid a stall in most trikes has much more
to do with the way the wing works without compensating surfaces and
the way the craft behaves near the stall angle of attack. For a
trike there is a range of AOA's where the stall occurs, generally
occurring at the smallest angle of attack in the center of the
wing. Since this part of the wing is also the furthest forward, a
loss of lift there tends to lower the angle of attack preventing
further development of the stall. If you continue to force it the
stall will progress slowly out the length of the wing, all the while
moving the center of lift farther and farther aft and doing all that
can be expected to undo the stall development. Of course, all of
this presupposed the CG is within a reasonable range.
HF
highflyer
>
> Rob wrote:
> >
> > j...@ix.netcom.com wrote:
> > >
> > > Sounds like a very interesting idea, but if it does work reliably at all speeds
> > > and altitudes, why does the Navy use a vane-type AOA indicator on their fighter
> > > aircraft?
> >
> > probes on the forward right side of the aircraft that had two slots in
> > them. It would rotate with the angle of attack. It was also heated.
> >
> > ... Rob
>
> The idea of the airspeed indicator as AOA indicator is for people
> with no electrical systems.
>
> If my airplane has an electrical system I would simply cobble up
> an AOA indicator using a vane mounted on a pot out on the pitot
> probe, that would be wired into a voltmeter on the panel
> with the face calibrated for AOA.
>
> john
And if you don't have an electrical system you can just look at the
vane! It gives you exactly the same information without the electrical
intermediary to calibrate.
HF
mark....@sciatl.com
But the vane is out in front of the wing, yes? Also, it has to be mounted
far enough to one side to be out of the prop blast (in a tractor, much less
of a problem for a pusher).
So I'm doing a final, it's bumpy and there's some cross wind so I'm trying to
dial in the right amount of slip, line up with the runway and control the
glide path. Now to use the AOA I have to keep glancing out in front of the
wing to try and see that vane?
Does this sound user friendly?
And as for using a pot, do they make one that is sealed against weather,
small, good for 100K+ cycles, and cheap? I'm serious here. If there is one
I'd like to know about it.
Thanks,
Mark Napier
Richard Lamb
is on the left side of the fuselage, just
forward of the cockpit.
(where you obviously can't see it in flight)
Just pointing out that is doesn't have to be
on the wing.
minot piper e
firewallforward from tripacer. 80 hrs total time
lost hanger, must sell. acft in arizona don't
email, call 520-775-0523
David Munday
>
>But the vane is out in front of the wing, yes? Also, it has to be mounted
>far enough to one side to be out of the prop blast (in a tractor, much less
>of a problem for a pusher).
>
>So I'm doing a final, it's bumpy and there's some cross wind so I'm trying to
>dial in the right amount of slip, line up with the runway and control the
>glide path. Now to use the AOA I have to keep glancing out in front of the
>wing to try and see that vane?
>
You'll be looking all around for traffic anyway won't you? And once
you are stabilized on approach you can hear and feel changes in state
can't you?
You could always point a mirror at it. Put it on top of the
instrument panel next to the compass.
--
David Munday - mund...@muohio.noise.edu
My email address is not noisy.
Webpage: http://www.nku.edu/~munday
PP-ASEL - Tandem Flybaby Builder - EAA-284 (Waynesville, OH)
"A member shall not speak oftener than twice, without special leave, upon the same question; and not the second time, before every other, who had been silent, shall have been heard, if he choose to speak upon the subject."
- Rules of the American Constitutional Convention, 1787.
Charles K. Scott
Richard Lamb <lam...@flash.net> writes:
If it's a tractor engine the vane would need to be mounted out of the
prop blast.
Corky Scott
David Hyde
: The vane on the A-4 (Love them Scooters!)
: forward of the cockpit.
: (where you obviously can't see it in flight)
Hehehe...but you could always look at the slats -
1/2 extended = on-speed AOA
Dave 'as long as they both extend' Hyde
na...@glue.umd.edu
RAH15/?
highflyer
>
> The vane on the A-4 (Love them Scooters!)
> is on the left side of the fuselage, just
> forward of the cockpit.
> (where you obviously can't see it in flight)
>
> on the wing.
But it does have to be out of the prop blast.
HF
Doug Johnson
(Charles K. Scott) wrote:
>In article <365A1679...@flash.net>
>Richard Lamb <lam...@flash.net> writes:
>
>> The vane on the A-4 (Love them Scooters!)
>> is on the left side of the fuselage, just
>> forward of the cockpit.
>> (where you obviously can't see it in flight)
>>
>> Just pointing out that is doesn't have to be
>> on the wing.
>
>If it's a tractor engine the vane would need to be mounted out of the
>prop blast.
>
>Corky Scott
If it is a tractor, they have made some radical design changes
on the Scooter since I flew it.
Doug Johnson
Http://www.skyray.com
Accident Investigator Extraordinary