Record height for a winch launch?
MHende6388
longest cable.
Michael
Quietpilot
Blanik L-13 from the end of 3500 feet of 1/8 inch shrouded steel cable and
manage close to 1000 feet of altitude at release at our summer playground of
Jacumba, California using a WWII winch.
It was one of the best rides around!
MG
Ray Lovinggood
Ray Lovinggood,
Carrboro, NC, USA
==============================================================
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Bill Daniels
midfield and a lightweight girlfriend in the front seat of our Grob 103,
managed 2700' AGL on our old wheezy winch with 5300' of wire.
Yesterday, I managed 2000' AGL with my Lark at 1300 pounds GW against an 8
Kt. wind on the same winch with a rebuilt engine.
I'm sure neither of these are records but they sure were fun.
Bill Daniels
"MHende6388" <mhend...@aol.com> wrote in message
news:20010304190008...@ng-fi1.aol.com...
Ray Lovinggood
>We have a lad who, with the help of a 25 Kt. headwind, a 8 Kt, thermal
>midfield and a lightweight girlfriend in the front seat of our Grob 103,
>managed 2700' AGL on our old wheezy winch with 5300' of wire.
WOW! 2700' with a G-103?! That is amazing! I'll tip my hat to the pilot and the winch operator for a launch nicely done!
Ray Lovinggood,
Carrboro, North Carolina, USA
John Giddy
cable. Our own record is about 3200 ft in a strong cool
wind. This last was done *without* "kiting" (paying out of
the winch cable at the top of the launch), which is illegal
under GFA Regulations. We use a two drum TOST winch, with
450 cu.in. Chev petrol engine, and 2.8 mm dia spring steel
solid cable.
Sorry for the mixed units. Altitudes are always quoted in
feet in Oz, to be consistent with ICAO. Everything else is
metric except American engine specs.
John G.
--
John Giddy Mangalore Gliding Club Inc.
5/287 Barkers Rd. http://www.gfa.org.au/vic/mgc/
Kew, Vic. 3101
Australia
Ray Lovinggood <REMOVE_TO_...@intrex.net> wrote in
message news:97uv6i$qkbrj$1...@ID-49798.news.dfncis.de...
Eggert Ehmke
wrote:
>We have a lad who, with the help of a 25 Kt. headwind, a 8 Kt, thermal
>midfield and a lightweight girlfriend in the front seat of our Grob 103,
>managed 2700' AGL on our old wheezy winch with 5300' of wire.
Last summer we got 600 to 650 m (2000 feet) on a regular basis with 3000
feet of cable and some headwind. That's for a ASK21 and a Grob Twin III,
double seated, no lightweight pilots.
--
Eggert Ehmke
Email: eggert...@berlin.de
Peter Thomas
cable at strong headwind. With a Schleicher K-13,
double seated, no lightweight pilots....
--
Peter
MHende6388 <mhend...@aol.com> schrieb in im Newsbeitrag:
20010304190008...@ng-fi1.aol.com...
Jean Richard
>
> Sorry for the mixed units. Altitudes are always quoted in
> feet in Oz, to be consistent with ICAO.
ICAO official units are SI. Feet and knot are considered as
exception units and should disapear some day (maybe in 2020 ;-)))
Jean
F.L. Whiteley
"Ray Lovinggood" <REMOVE_TO_...@intrex.net> wrote in message
news:97uv6i$qkbrj$1...@ID-49798.news.dfncis.de...
> >We have a lad who, with the help of a 25 Kt. headwind, a 8 Kt, thermal
> >midfield and a lightweight girlfriend in the front seat of our Grob 103,
> >managed 2700' AGL on our old wheezy winch with 5300' of wire.
>
>
> WOW! 2700' with a G-103?! That is amazing! I'll tip my hat to the pilot
and the winch operator for a launch nicely done!
>
>
Frank Whiteley winch driver.
Dillon Krapes pilot
Not sure who the passenger/student was for that one.
Colorado Soaring Assn
FWIW, he came off the top in 6knots of lift that eventually got to 9knots or
so. I thought he sure looked high at the end of that cable.
We suffer due to being at 5500msl, but are fortunate to have a mile fence to
fence to lay wire rope. We hope to do better with spectra one of these
days. Bill's launch Saturday in the Lark used considerably less than the
full length. The Grob seemed to be doing as well as the Lark. The engine
is still a little tight and should work a bit better once the rings get
seated.
I recall an RAF story, by the CFI-G pilot I cannot name (Gordon?), of having
kited to 3200agl
at RAF Kinloss in a K-8. This would have been in the late '70s.
Bill Daniels
"Ray Lovinggood" <REMOVE_TO_...@intrex.net> wrote in message
news:97uv6i$qkbrj$1...@ID-49798.news.dfncis.de...
> WOW! 2700' with a G-103?! That is amazing! I'll tip my hat to the pilot
and the winch operator for a launch nicely done!
>
A tip of the hat to Frank Whiteley, our premiere winch driver and pilot
Dillon Krapes, now one of our instructors.
These 2000' AGL plus winch launches points up that fact that winches,
properly designed and operated, are a serious way to get airborne. Winch
launches to these altitudes provide about the same opportunity to find
thermals as an airtow since most airtow launches are to about the same
altitude and the glider releases near the airfield anyway.
Several advantages come to mind:
1. The cost of winch launches is MUCH lower than air tow.
2. The winch launch is MUCH less irritating to airport neighbors.
3. Winch drivers are much easier to find and train than tug pilots.
4. (Here's a controversial one) Winches represent a much greater "uphill
capacity" than a tug if you look at vertical feet per day. One multi-reel
winch equals two or more tugs.
5. Winch maintenance can be done by any competent mechanic whereas a tug
needs to be maintained and inspected under government scrutiny.
Bill Daniels
Kirk Stant
> ICAO official units are SI. Feet and knot are considered as
> exception units and should disapear some day (maybe in 2020 ;-)))
>
> Jean
Why? While I may agree that metric units are OK for ground use, in the air
and on the sea the Nautical mile (one minute of latitude) is the preferred
unit of distance, easily measured on any chart, and is likely to remain so
for the foreseeable future. Therefore, the Knot is the most useful unit of
speed. As far as altitude, feet are just as useful as meters, why change?
For soaring, using Knots for airspeed and climb is nicely consistent and
makes for easy guesstimating of instantaneous glide angle. And since a
nautical mile is just over 6000' (6080'), one can easily use multiples of
nautical miles per 1000' for mental figuring glide distances: 36/1 is 6
nm/1000', 30/1 is 5 nm/1000', 24/1 is 4 nm/1000', and so on. Try doing
any of that with Kph, Meters, and M/Sec!
I'm not a Europhobe (I'm half French, and have lived in Europe many years)
but I do think that, for aviation at least, the archaic foot, nautical mile,
and Knot should remain in place indefinitely. Now if we could only get US
soaring pilots to stop using MPH and statute miles for speeds and distances,
instead of the Knots and NM they use in-flight, we would be getting
somewhere! It's bad enough having to figure if you have enough NM to make
your 500K flight, but then you have to convert that into Statute miles for
club bragging rights!
Kirk Stant
LS6 "66"
Vive les pieds! A bas les Metres (une vrai connerie!)
Torben Kristensen
headwind without kiting. Lesson of the day was that flying a Ka8 in 30+ kts.
wind was not a particular bright idea for a low time pilot.
Torben
Robert Ehrlich
> ...
> 3. Winch drivers are much easier to find and train than tug pilots.
This point is not obvious. Many power pilots are happy to fly for
free while aerotowing, but the poor glider pilot who sits in the
winch while the others are flying is usually not very happy. So
you get more volunteers in the first category than in the second one.
Robert Ehrlich
>
> Jean Richard <j.ri...@sympatico.ca> wrote in message
>
> > ICAO official units are SI. Feet and knot are considered as
> > exception units and should disapear some day (maybe in 2020 ;-)))
> >
> > Jean
>
> Why? While I may agree that metric units are OK for ground use, in the air
> and on the sea the Nautical mile (one minute of latitude) is the preferred
> unit of distance, easily measured on any chart, and is likely to remain so
> for the foreseeable future. Therefore, the Knot is the most useful unit of
> speed. As far as altitude, feet are just as useful as meters, why change?
> For soaring, using Knots for airspeed and climb is nicely consistent and
> makes for easy guesstimating of instantaneous glide angle. And since a
> nautical mile is just over 6000' (6080'), one can easily use multiples of
> nautical miles per 1000' for mental figuring glide distances: 36/1 is 6
> nm/1000', 30/1 is 5 nm/1000', 24/1 is 4 nm/1000', and so on. Try doing
> any of that with Kph, Meters, and M/Sec!
If you count vertical and horizontal distances with the same unit it is
much easier. Most european glider pilots do so and most european glider
instruments use meters for the altimeter and m/s for the vario. The pain is
that airspeed is in km/h rather than in m/s, which is used on varios and BTW
is the SI unit for speed. But for mental figuring glide ratios, in the same way
you use for distance in nautical miles vs feet, we can for speed in km/h vs m/s
remember some key values: 20 m/s is 72 km/h, 25 m/s is 90 km/h, 30 m/s
is 108 km/h. Anyway we have more often to compare vertical and horizontal
distances than vertical and horizontal speeds, where anyway the result is
biased by the fact that the error due to density altitude is not the
same for the ASI and the vario. Usually the relashionship beteween vertical
and horizontal speed is rather figured using the Mc Cready ring (or a
computer if you are rich), and then the conversion is already made for you.
> Vive les pieds! A bas les Metres (une vrai connerie!)
Vive les m/s, a bas les km/h. Les US nous cassent les pieds avec leur pieds :-)
Larry Goddard
Larry
Bill Daniels
"Robert Ehrlich" <Robert....@inria.fr> wrote in message
news:3AA3F0E1...@inria.fr...
Agreed - if the power pilots meet insurance requirements. Most tugs are old
rag-and-tube taildraggers. Insurance companies are getting more and more
reluctant to insure pilots without 100's of hours in taildraggers. We find
lots of volunteer pilots but few that meet the insurance requirements. My
only point is that it takes a lot longer to make a tug pilot than train a
winch driver if you start from the same level of skill.
Also agreed that the typical winch is pretty short on creature comforts and,
if not fully enclosed, can be hazardous as well as boring. My theory is to
make the winch cab weather-tight, sit at least two, (driver + trainee) add
climate control and any other creature comforts desired to make the job more
attractive.
Personally, if conditions are not booming, I'm happy driving the winch or
instructing in the glider. I find either an interesting diversion.
Bill Daniels
Bruce Hoult
<wdan...@uswest.net> wrote:
> These 2000' AGL plus winch launches points up that fact that winches,
> properly designed and operated, are a serious way to get airborne. Winch
> launches to these altitudes provide about the same opportunity to find
> thermals as an airtow since most airtow launches are to about the same
> altitude and the glider releases near the airfield anyway.
Winches are great, but 2000 ft over the end of the airfield is only
worth about the same as 1500 ft from a typical towplane that puts you in
the general direction of the lift.
That's often enough, but not always -- good thing winch launches are
cheap.
-- Bruce
Greybeard
>
> If you count vertical and horizontal distances with the same unit it is
> much easier. Most european glider pilots do so and most european glider
> instruments use meters for the altimeter and m/s for the vario.
And most european glider pilots are used to using the units, which almost
all US glider pilots would find confusing. Safety issues are more important
than the continued glorification of the metric "system". I am used to
seeing 45 mph over the threshold, and 45 kph wouldn't be a good idea.
Turning onto base at 55 kph and 500 meters would also be quite exciting.
I'll stick with the units I'm familiar with.
Greybeard
Timo
using roughly 5900 ft cable.
TK
MHende6388 <mhend...@aol.com> wrote in message
news:20010304190008...@ng-fi1.aol.com...
Jean Richard
>
> And most european glider pilots are used to using the units, which almost
> all US glider pilots would find confusing.
Untrue !
> Safety issues are more important
> than the continued glorification of the metric "system".
That a good reason to go metric then !
> I am used to
> seeing 45 mph over the threshold,
I'm used to look at the end of the runway over the threshold, not
on my airspeed indicator ;-))
> and 45 kph wouldn't be a good idea.
Don't you have a small triangle on your airspeed indicator ? They are
mandatory since more than twenty year. They are used as a reminder of
the no wind recommanded approch speed.
Jean
Jean Richard
> Why? While I may agree that metric units are OK for ground use, in the air
> and on the sea the Nautical mile (one minute of latitude) is the preferred
> unit of distance, easily measured on any chart, and is likely to remain so
> for the foreseeable future. Therefore, the Knot is the most useful unit of
> speed. As far as altitude, feet are just as useful as meters, why change?
I've been flying in Europe a few times and really appreciate to have
altimeter in metre and not in feet since it's a lot easier to make
glide calculations.
I would like to get rid of our feet calibrated altimeter (I'm living
and usually flying in North America...).
As so far distance is concerned on a chart, we always use metres, and
it's also a lot easier since you just take any rule to mesure distance
and convert it from centimetres to kilometres.
> For soaring, using Knots for airspeed and climb is nicely consistent and
> makes for easy guesstimating of instantaneous glide angle.
No ! Because your airspeed is not indicating ground speed, but airspeed.
Here, we are sometimes happy to have GPS since they all work in SI.
> And since a
> nautical mile is just over 6000' (6080'), one can easily use multiples of
> nautical miles per 1000' for mental figuring glide distances: 36/1 is 6
> nm/1000', 30/1 is 5 nm/1000', 24/1 is 4 nm/1000', and so on. Try doing
> any of that with Kph, Meters, and M/Sec!
Distance in km and altitude in metres. That's all we need. Airspeed and
vario are not used for gliding calculation, just for speed to fly -
the Mac Cready (or any more sophisticated device) do the job for you.
> I'm not a Europhobe
SI units is not only for Europe. It's the official unit system in all
America, except USA.
> (I'm half French, and have lived in Europe many years)
> but I do think that, for aviation at least, the archaic foot, nautical mile,
> and Knot should remain in place indefinitely.
At first, ICAO want to discard anything except SI. But due to difficulties
in conversion (and cost), ICAO went for a « temporary » exception chart to
included some non SI units. The MPH are no more accepted (here in Canada,
selling a new airplane with MPH airspeed indicator is not legal).
> Now if we could only get US
> soaring pilots to stop using MPH and statute miles for speeds and distances,
> instead of the Knots and NM they use in-flight, we would be getting
> somewhere!
SI is easier... Weather observation (METAR) in USA are mixing knots (wind)
with statute miles (visibility), and feet (I don't know if Imperial feet
and US feet are the same), inches of mercury. What a mess !
> It's bad enough having to figure if you have enough NM to make
> your 500K flight, but then you have to convert that into Statute miles for
> club bragging rights!
FAI distance badges are in kilometres, nothing else ;-))
> Vive les pieds! A bas les Metres (une vrai connerie!)
J'ai toujours préféré les maîtres aux pieds ;-))))
Jean
Jean Richard
>
And if the poor glider pilot is a poor young boy or young girl, still
attending school, too poor to have a PPL, and with just enough money
for club membership fees. Then, having some launch and flight credit
from winch operating can help him or her...
Bravo Challes-les-Eaux...
Jean
Kirk Stant
> J'ai toujours préféré les maîtres aux pieds ;-))))
>
> Jean
Jean,
I could take all your arguments, switch units, and get exactly the same
result. Any measuring system is arbitrary, and other than the fact that the
metric system is a decimal system, it is just as (if not more - still have
that platinum rod in Paris?) arbitrary than most! All we are proving is
that pilots prefer what they are used to. If the book says approach at 80
somethings, then approach at 80 somethings! Incidentally, most older
gliders in the US (read Schweizers) have airspeed in Mph, with no markings
on the ASI (except maybe an added-on redline at VNE). It's just a number,
after all...
Gliders and small planes in Europe (and other places, granted) may use Km
and meters, but all "professional" and military flying in the western world
uses Knots and NM (not Mph and statute, please). If you fly in the "system"
just about anywhere, you will be using Knots and feet for speed and
altitude. And all airplanes made and sold in the US, from Cessnas to
Boeings, use Knots and feet. It ain't going to change!
And why would you want to measure distances in Km when Nautical miles are
right there on the chart, already adjusted for the mapping projection error?
Only an amateur navigator (and I was a professional one in a previous life)
would prefer Km over Nm.
SI may end up taking over the day to day weights and measures (a few more
satellite launch failures may guarantee that!), but I seriously doubt we
will see all of aviation change to it - it'll be Knots and Feet forever,
even in an Airbus!
A bientot,
Kirk Stant
LS6 "66"
Greybeard
> Greybeard wrote:
> >
> > And most european glider pilots are used to using the units, which
almost
> > all US glider pilots would find confusing.
>
> Untrue !
I went through the "metric conversion" at my work, don't tell me it isn't
confusing. Suddenly, we didn't have any 3/4 inch shafting anymore, but
19.05mm. Do your math, I got pretty good at it. Oh, yes. No more 1 inch
shafting either, 25.40 mm. I now work in my own units, the "Pitlar".
Stands for Ph*** It, That Looks About Right.
>
> > Safety issues are more important
>
> That a good reason to go metric then !
And a better reason not to change. Metric is a system of measurement, man
made, and is subject to all the mistakes man can make. It isn't something
God gave us.
>
> Don't you have a small triangle on your airspeed indicator ? They are
> mandatory since more than twenty year. They are used as a reminder of
> the no wind recommanded approch speed.
>
Mandatory by who? In my glider all I'm required to have and is mandatory is
an airspeed indicator. However, as you wish me to update, (or downgrade)
all of my instruments, when can I expect the check?
Greybeard.
BAToulson
<grey...@mwci.net> writes:
>And most european glider pilots are used to using the units, which almost
>all US glider pilots would find confusing.
What about we Brits?? We are being dragged kicking and screaming into the
metric system but our aviation still operates in Knots for speed, (nautical
miles per hour as opposed to road maps which use statute miles),and feet for
altitude.
When will the rest of the world fall in line!!!!!
Barney
UK
John Giddy
We don't have them in Oz. I have seen one in a glider in
Switzerland, but my memory was that it indicated "speed for
least sink".
Training should result in the pilot being able to judge
approach speed *without* an ASI, and too much study of the
ASI on final usually leads to a poorly set up approach,
since the pilot tends to "Chase the ASI", leading to more
speed fluctuation than if attitude and wind noise are used
as indicators of speed.
(Flame suit ON)
Cheers, John G.
John Giddy Mangalore Gliding Club Inc.
5/287 Barkers Rd. http://www.gfa.org.au/vic/mgc/
Kew, Vic. 3101
Australia
Jean Richard <j.ri...@sympatico.ca> wrote in message
news:3AA4D9...@sympatico.ca...
Greybeard
>
> Here, we are sometimes happy to have GPS since they all work in SI.
All, Jean? I don't think so.
>
> SI units is not only for Europe. It's the official unit system in all
> America, except USA.
Why do you care? except maybe it's the fact that the metric system was
formulated in a certain town called paris? Get off it, Jean.
>
> SI is easier... Weather observation (METAR) in USA are mixing knots (wind)
> with statute miles (visibility), and feet (I don't know if Imperial feet
> and US feet are the same), inches of mercury. What a mess !
Only if you have to convert it to understand it. I don't have any problem
with it. Having been through the "conversion" that happened in our
factories, I really don't have much sympathy for those that have to convert
to our units. I did it, you can too, or can't you?
>
> FAI distance badges are in kilometres, nothing else ;-))
Who cares? They're not here, I'm not there.
>
Climb off your anti-USA soapbox Jean. You don't impress me with anything
you've stated.
Greybeard.
Caracole
The little yellow triangle on Airspeed indicators from
German manufactured gliders (the last 20 years worth)
which have not had owner exchanged instruments (chuckle)
is commonly mis-interpreted as any of these:
1) Best L/D speed
2) Approach speed in calm conditions
3) Minimum sink speed .....
and other permutations, by order of popularity of answer.
In most German flight manuals, it is recorded as
minimum recommended approach speed. This leaves
a little room for losses in translation of intent from
German into English.
We admonish students and renters that it is ....
European minimum recommended approach speed for the worst
approach configuration, i.e.. gross weight and full spoilers.
At that configuration and speed, you will "JUST" have
flare authority to arrest sink rate.... and be done flying.
Don't flare high.....
We typically teach students to fly pitch attitude and
correlate that to indicated speeds, and we ask them
to fly patterns a nudge faster than the yellow triangle for
calm conditions, and also adjust for half wind component
on final leg.
No flames here, just 1 inch of rain in 12 hours.
Cindy B
John Giddy <jgi...@melbpc.org.au> wrote in message
news:983t7t$q06$1...@possum.melbpc.org.au...
John Giddy
I agree with your discussion.
We also teach pattern and approach as you indicate. None of
our ships has a triangle marker, so we use the rule of thumb
"1.5 times stall speed plus half the wind speed" to find a
suitable pattern/approach speed. Seems to work well.
Its been a long hot dry summer down here (central Victoria),
but not as many days of good soaring weather as that would
indicate. Rather a poor season, in fact.
Cheers, John G.
John Giddy Mangalore Gliding Club Inc.
5/287 Barkers Rd. http://www.gfa.org.au/vic/mgc/
Kew, Vic. 3101
Australia
Caracole <Cara...@ccis.com> wrote in message
news:cvip6.349$Cd.81...@news.randori.com...
Christian Husvik
Since we are about p/2 (thats pi/2 if the character set f***s up) off topic
already...
"Greybeard" <grey...@mwci.net> wrote in message
news:taa6l66...@corp.supernews.com...
>
> I went through the "metric conversion" at my work, don't tell me it isn't
> confusing. Suddenly, we didn't have any 3/4 inch shafting anymore, but
> 19.05mm. [...]. Oh, yes. No more 1 inch
> shafting either, 25.40 mm. [...]
Well, to me it looks like you didn't really do the conversion after all.
3/4 inch shafting is still 3/4 inch even if you measure it with milimeters?
Christian 8-)
Bert Willing
it is actually the speed you should use on final in calm conditions.
I never look at that triangle, there are much more interesting things to see
outside, and I trust my feeling a lot more than small triangles.
--
---------------------
Bert Willing
Calif A21S
Come fly at La Motte du Caire in Southern France:
http://la-motte.decollage.org
Caracole <Cara...@ccis.com> a écrit dans le message :
cvip6.349$Cd.81...@news.randori.com...
Jean Richard
>
> I guess you mean "mandatory in Canada" ?
JAR
> We don't have them in Oz. I have seen one in a glider in
> Switzerland, but my memory was that it indicated "speed for
> least sink".
No. Speed for best no wind glide.
On almost all gliders, best no wind approch speed and best no
wind glide are the same.
> Training should result in the pilot being able to judge
> approach speed *without* an ASI, and too much study of the
> ASI on final usually leads to a poorly set up approach,
> since the pilot tends to "Chase the ASI", leading to more
> speed fluctuation than if attitude and wind noise are used
> as indicators of speed.
> (Flame suit ON)
No flame problem with me on that subject. I agree... Chasing the
ASI is the worst thing to do when flying.
Jean
Jean Richard
>
> The little yellow triangle on Airspeed indicators from
> German manufactured gliders (the last 20 years worth)
> which have not had owner exchanged instruments (chuckle)
> is commonly mis-interpreted as any of these:
>
> 1) Best L/D speed
> 2) Approach speed in calm conditions
> 3) Minimum sink speed .....
> and other permutations, by order of popularity of answer.
Best answer is 2) - but it is often the same as 1)
3) is wrong...
Chapter 522 (from JAR-22)
522.1545
(Mine is in French - I will translate and abbreviate)
Each airspeed indicator MUST have following marks
a) Radial red line for Vne
b) Yellow from Vra to Vne
c) Green from 1.1 Vsi to Vre at max gross mass, no flaps and gear up (if
retractable)
d) White from 1.1 Vso to Vfe at max gross mass
e) Yellow triangle for minimum recommanded (by designer) approch speed at
max mass (not ballasted)
f) Radial blue line for best climbing speed (self launched gliders)
For controls...
522.780
Cable release - Yellow
Airbrakes - Blue
Trim - Green
Canopy latches - White
Canopy jettison - Red
Other - None of those above
> In most German flight manuals, it is recorded as
> minimum recommended approach speed. This leaves
> a little room for losses in translation of intent from
> German into English.
But there was no loss ;-))
> We admonish students and renters that it is ....
> European minimum recommended approach speed for the worst
> approach configuration, i.e.. gross weight and full spoilers.
Canada is not part of Europe but the same rules apply.
Then, « admonish » your pupils that it is STANDARD indication
of minimum approch speed - not in the worst case but in the
best, the minimum being for the best and any worstening condition
requesting a higher speed ;-)
Jean
Jean Richard
>
> Hi Cindy,
> I agree with your discussion.
> We also teach pattern and approach as you indicate. None of
> our ships has a triangle marker, so we use the rule of thumb
> "1.5 times stall speed plus half the wind speed" to find a
> suitable pattern/approach speed.
We ask them to read the manual first, the designer recommandation
being there for some reasons. Then, they adjust approch speed to
turbulence, not to wind speed.
In hot spring day, a flat gradient means no synoptic wind. But if
air is very unstable, this is the kind of situation where you have
to expect gusts coming from any direction. There's no wind for
many minutes, then a 40 km/h gust suddenly change the picture.
Jean
Jean Richard
>
> Why do you care? except maybe it's the fact that the metric system was
> formulated in a certain town called paris?
Metric formulated some years ago is not SI. SI is for Système International.
It's from an international agreement.
Old metric were using bars (for pressure), SI, pascals.
Old metric was using kilogram for weight. SI is using newton.
Many more difference (calorie, cheval-vapeur... are gone).
Jean
Robert Ehrlich
Although there are some differences between old metric system and SI, the
general idea is the same. Before the metric system, units used were depending
on so many things as the (sub)nationality of the user, the specific thing
or domain of things you mesure, heigths in feet, sea depth in fathoms, travel
length in miles or yards, and the real value of each unit was changing even
in different parts of the same country. This may be considered as suitable
in a world where communication was mainly limited to small groups of persons
sharing the same activities and units, but became more and more unpractical
as communications developped as well as science which was able to consider
more and more apparently unrelated domains to have some connections. The
fact that the change took place in Paris first is an historical accident due
to the fact that, due to the other big changes happening there at this time,
the change to an uniform system of measurement was easier to introduce there
and then. But later almost the whole world made progressively the same switch.
Only the USA persist now in the old system, because only the USA are sufficiently
big and powerful to force others nations to use their own system rather than
agree on a common system. But as I think US citzens are rational people, I
think that soon or later they will recognize the advantage of a logical and
uniform system of measurement and switch to it. Anyway it is amazing to see
that the nation which claims to be the leader of the progress in the world
sticks in this way to this middle-age system.
Greybeard
> But as I think US citzens are rational people, I
> think that soon or later they will recognize the advantage of a logical
and
> uniform system of measurement and switch to it. Anyway it is amazing to
see
> that the nation which claims to be the leader of the progress in the world
> sticks in this way to this middle-age system.
The problem is cost, mainly, and familiarity with the system we use. For an
example, being a machinist, I have my own micrometers up to 6 inches. I do
not have the $1200 that it would take to replace them with the metric
equivalents. I'm only one of millions, and that cost is hard to justify.
If I were to add on all of my other instruments, my personal cost would be
close to $10000. Thanks to the abortion known as ISO 9000, the companies,
if they are to use the metric system, must use metric instruments. I have
seen just what this cost the company I retired from, $2400 for a new set of
gage blocks, and $50000 for a measuring machine that worked in mm instead of
inches. That's only one calibration lab out of 15 that they have, and only
one company, that I also expect to see extinct within 5 years. (Bought by a
foreign corporation) Then there's the small matter of the 7000 gages that
were on the factory floor, and the costs get big very quickly. There are
many, many factors that make conversion on a national scale entirely
impractical if not impossible.
Greybeard
Jean Richard
>
> Before the metric system, units used were depending
> on so many things as the (sub)nationality of the user,
Canada went to SI in the seventies. Even if Canada is close to USA,
it never used the same system. Canada was using imperial units and
USA their own local system.
Some units were common to both countries (inches, feet, yards,
statute miles), but some were different (and you never know which
ones... gallons were different - US gallons were smaller so they
can make you believe that it was cheaper to buy in USA...).
Worst, units were different depending on the language you talked.
A pint of milk was just half a « pinte de lait ».
Switching to SI was the best choice. Canada did it and only a few
nostalgics would like to back to the imperial system. That doesn't
mean that we go to SI only. There is some situation where imperial
or other systems are in use (aviation is just partly SI, house
building material too - and eggs are still sold by dozens ;-)))
But USA is not fully US system. They are also using imperial units
as well as SI units. Old wrenches with sizes like 3/64, 1/8, 1/4,
5/32, 9/64 inch are now usuless if you want to fix your car. You
have to use 10, 11, 15, 17 mm and so. Don't look for Fareinheit
degrees in US METAR. It's Celsius. Don't look for isobas in inches
of mercury or isohypses in feet on weather analysis charts. You will
find hectopascals and decametres. Don't look for mph for windspeed,
you will find knots (which is not US nor imperial).
> The
> fact that the change took place in Paris first is an historical accident
But I'm sometimes wandering if it's not a big bug for some people ;-)))
> But later almost the whole world made progressively the same switch.
> Only the USA persist now in the old system, because only the USA are sufficiently
> big and powerful to force others nations to use their own system rather than
> agree on a common system. But as I think US citzens are rational people, I
> think that soon or later they will recognize the advantage of a logical and
> uniform system of measurement and switch to it.
In Canada, SI entered by the front door, after a well documented political
decision. In USA, SI is entering by the back door, without making too much
noise, to avoid awakening of old political devils ;-)))
To stay with soaring, I don't find too practical to say that :
- a standard class glider has a 49 feet 2 35/64 inches wingspan ;
- your FAI Silver badge request a 3281 feet (rounded up value) altitude gain ;
- the same FAI Silver badge request a slightly more than 31 miles distance ;
- and are US hours the same as hours used in the rest of the World ? ;-))
Jean
Jan Lustrup
And 2 by 4's are still 2 by 4's ;)
Jan Lustrup IK3
Alex Upchurch
> - and are US hours the same as hours used
> in the rest of the World ? ;-))
If the SI committee ever get around to implementing the 100 hr day, I'll
have four times longer to accomplish everything in a day...
Alex :-)
Lester Hawksby
> think that soon or later they will recognize the advantage of a logical
and
> uniform system of measurement and switch to it.
arbitrary. It certainly can't claim the title logical. Kilograms are just as
arbitrary as pounds (a kilogram is not, in fact, the mass of a litre of
water blah blah blah. It's a bit less than that. It is in fact defined as
the mass of the International Standard Kilogram, a metal block in Paris).
Metres are just as arbitrary as yards (1/10000000 of an incorrect
measurement of some part or other of the earth? Some bloody awkward number
of radiation wavelengths? Logical?).
As for uniformity: All unit systems will just give different constants. None
has any advantage there.
Three good reasons why Imperial is a good idea:
(i) intuitive units. I was brought up on SI units, but I can't guess
dimensions in centimetres or distances in metres or kilometres. Inches,
yards and miles, no problem. I suspect it's because most people have finger
bones approximating an inch, a comfortable (if substantial) step approaching
a yard, etc.
(ii) convenient divisions. Imperial may have odd subunits (hundredweight,
chains) but that's because they're convenient units to measure in. Metric
was devised all in one go as an ideology, which happens not to be
particularly handy in many situations. Imperial evolved over hundreds of
years, to suit actual requirements. Some, I freely admit, are obsolete.
Others aren't. Some (don't ask me for specific examples at 1:18am) came into
common use AFTER Metric (which is, after all, 200 years old).
(iii) Imperial units divide by more things. For instance, the foot is
divisible evenly by 2,3,4 and 6 inches. Metric units, being multiples of 10,
are divisible only by 2 and 5. Also, Imperial positively encourages its
users to work with fractions, an immensely superior system to decimals with
their implied inaccuracy and incompatiability with mental arithmetic.
> Anyway it is amazing to see
> that the nation which claims to be the leader of the progress in the world
> sticks in this way to this middle-age system.
Imperial measurements (or their descendants, the US system, which is simply
a yet further development of Imperial) have been a continuously evolving
system for hundreds of years, and are thus *less* obsolete than their
Metric/SI equivalents, laid down by decree for reasons not practically
inspired 200 years ago and not much changed.
- Lester Hawksby
Jean Richard
> > - and are US hours the same as hours used
> > in the rest of the World ? ;-))
>
> If the SI committee ever get around to implementing the 100 hr day, I'll
> have four times longer to accomplish everything in a day...
No, they will go for a 10 hour day (and employers will be very happy
since they won't change the hourly rate of their employees ;-))
Jean
Bert Willing
preferred to blow up that vessel in the marsian atmosphere :-)
Sorry, couldn't resist.
--
---------------------
Bert Willing
Calif A21S
Come fly at La Motte du Caire in Southern France:
http://la-motte.decollage.org
Greybeard <grey...@mwci.net> a écrit dans le message :
tadbupf...@corp.supernews.com...
Robert Ehrlich
>
> > But as I think US citzens are rational people, I
> > think that soon or later they will recognize the advantage of a logical
> and
> > uniform system of measurement and switch to it.
> I beg to differ. The unit definitions in SI are completely and utterly
> arbitrary. It certainly can't claim the title logical. Kilograms are just as
> arbitrary as pounds (a kilogram is not, in fact, the mass of a litre of
> water blah blah blah. It's a bit less than that. It is in fact defined as
> the mass of the International Standard Kilogram, a metal block in Paris).
> Metres are just as arbitrary as yards (1/10000000 of an incorrect
> measurement of some part or other of the earth? Some bloody awkward number
> of radiation wavelengths? Logical?).
>
A kilogram is no more the mass of a litre of water in its definition, but it
is suffciently close to it that you can consider it is that for most practical
use, with certainly a lower error than assuming your finger bones approximate
an inch, especially in my case or in the case of most women. The same thing
is true for the meter and 1/40000000 of the circumference of the earth.
> As for uniformity: All unit systems will just give different constants. None
> has any advantage there.
The system where most constants are 1 has clearly an advantage. Maybe I
will switch to the foot as unit of length if you define it as the length
travelled by the light in 1 nanosecond :-)
>
> Three good reasons why Imperial is a good idea:
>
> (i) intuitive units. I was brought up on SI units, but I can't guess
> dimensions in centimetres or distances in metres or kilometres. Inches,
> yards and miles, no problem. I suspect it's because most people have finger
> bones approximating an inch, a comfortable (if substantial) step approaching
> a yard, etc.
>
Only a question of practice. When I am in the US it is very difficult for me
to figure what are distances or length in inches, feet, yards or miles,
what are temperatures in Farenheit, volumes in gallons and prices in dollars,
although for the last point I will soon have to face to the same problem
here with euro. But the worse thing is counting horizontal and vertical
distances with different units in a glider.
> (ii) convenient divisions. Imperial may have odd subunits (hundredweight,
> chains) but that's because they're convenient units to measure in. Metric
> was devised all in one go as an ideology, which happens not to be
> particularly handy in many situations. Imperial evolved over hundreds of
> years, to suit actual requirements. Some, I freely admit, are obsolete.
> Others aren't. Some (don't ask me for specific examples at 1:18am) came into
> common use AFTER Metric (which is, after all, 200 years old).
>
> (iii) Imperial units divide by more things. For instance, the foot is
> divisible evenly by 2,3,4 and 6 inches. Metric units, being multiples of 10,
> are divisible only by 2 and 5. Also, Imperial positively encourages its
> users to work with fractions, an immensely superior system to decimals with
> their implied inaccuracy and incompatiability with mental arithmetic.
>
Do you find easier to compute mentally what is 0.25 + 0.15 or 1/4 + 3/20 ?
Anyway again a question of practice. Most users of the decimal system will
find difficult to do mental arithmetic with fractions.
> > Anyway it is amazing to see
> > that the nation which claims to be the leader of the progress in the world
> > sticks in this way to this middle-age system.
> Imperial measurements (or their descendants, the US system, which is simply
> a yet further development of Imperial) have been a continuously evolving
> system for hundreds of years, and are thus *less* obsolete than their
> Metric/SI equivalents, laid down by decree for reasons not practically
> inspired 200 years ago and not much changed.
The main incentive for the new system 200 years ago was its practical benefits.
Scientists were among its main advocates and volunteered to do the earth
measurements involved. And concerning the evolution, the definition of the
basic units of mass, length and time constantly evolved when the progress
in measurement techniques and precision made the previous definition inadequate
or imprecise.
Anyway, beside this kind of nostalgy, the only drawback of the switch to metric
is, as Greybeard pointed out, the cost. But as I think this switch is unavoidable,
postponing it will only increase this cost. England and Canada clearly understood
that during the past decades.
Jakob Degn Jensen
news:20010304190008...@ng-fi1.aol.com...
> Curious what the highest sailplane launch from a winch has ever been for
the
> longest cable.
I have achieved 600m with 1000 m cable (5mm steel cable) with both Astir CS
and a Mucha std (SZD22a). I have heard of nearly 900m with this winch and
the Mucha in a strong wind using a kite technic. (Don't know if the story is
true)
Regards
Jakob
Greybeard
Bert Willing <wil...@ir-microsystems.com> wrote in message
news:3aa74dec$1...@epflnews.epfl.ch...
> Yep - NASA also didn't have the financial means to do proper conversions
and
> preferred to blow up that vessel in the marsian atmosphere :-)
>
Landed the Venera probes on Venus, and the french are watching the
cheerleaders from the sidelines. Don't open that can of worms, Bert.
Greybeard
Greybeard
>
> The system where most constants are 1 has clearly an advantage. Maybe I
> will switch to the foot as unit of length if you define it as the length
> travelled by the light in 1 nanosecond :-)
The meter is defined by a certain odd decimal of the number of wavelengths
of the yellow light of the singly ionized cessium atom. It does not even
work out to an even number of wavelengths. Have at it.
The main difference is that the imperial system was devised with access to
the most number of people that would need it. The SI was devised based on a
few "standards" that are locked away in a vault or totally inaccessable for
most people. Actually, all but a few technicians, and very expensive to get
a direct comparison to those standards.
In contrast, the imperial inch is or was defined as the length of "three
barleycorns, hard, round and uniform, layed end to end". Anyone can
duplicate this and come up with a fair approximation. Try that with your
light apparatus. As a secondary standard, the yard was defined as "The
distance from the tip of his imperial index finger to the end of his royal
nose", again, something that is quite easy to approximate, unlike the
changes in state of an ionized atom, in a vacuum. All of the SI units
require another SI unit to relate to, and all of them require laboratory
standards to even approximate.
But, as Lester pointed out, when it comes to human errors, no one system is
immune. Two factors go against the conversion of the US to the SI, the
first is cost, and the second is confusion. I use both if I have to, but
when someone wants something done to SI standards, it costs more. I have to
convert the numbers into the units of my instruments. Arguing that one
standard is better than another is ridiculous, none have any advantage over
what the person using it is familiar with.
Greybeard
>
Jean Richard
>
> Hmmmm. The US sent people to the moon and landers to Mars,
To discover that there was no good soaring conditions in those lands.
> the Russians Landed the Venera probes on Venus,
with the conclusion that Janus is better than Venus for soaring.
> and the french are watching the
> cheerleaders from the sidelines. Don't open that can of worms, Bert.
I visited La Motte du Caire and I understand why Bert doesn't want to
go on the Moon, on Mars or on Venus ;-))
Jean
Jeremy Harris [RU-UK]
"Lester Hawksby" <lh0...@bristol.ac.uk> writes:
> (i) intuitive units. I was brought up on SI units, but I can't guess
> dimensions in centimetres or distances in metres or kilometres. Inches,
> yards and miles, no problem. I suspect it's because most people have finger
> bones approximating an inch, a comfortable (if substantial) step approaching
> a yard, etc.
Oh, rubbish. To that level of accuracy, a metre is the _same_ as a yard,
and a centimetre is the width of your thumbnail.
- Jeremy
Jean Richard
>
> A kilogram is no more the mass of a litre of water in its definition, but it
> is suffciently close to it that you can consider it is that for most practical
> use, with certainly a lower error than assuming your finger bones approximate
> an inch, especially in my case or in the case of most women.
In French, words for inches, feet and yards are « pouces, pieds et verges ».
Then, those who understand French must admit that imperial system is
deeply macho (the verge being three times longer than the pieds) and sexist ;-)))
> Anyway, beside this kind of nostalgy, the only drawback of the switch to metric
> is, as Greybeard pointed out, the cost. But as I think this switch is unavoidable,
> postponing it will only increase this cost. England and Canada clearly understood
> that during the past decades.
That's right, at least for Canada. We are just trying to keep a few occasions
to use imperial units, to stay in touch with folklore ;-))
Jean
Robert Ehrlich
>
> Robert Ehrlich <Robert....@inria.fr> wrote in message
> news:3AA76A41...@inria.fr...
> >
> > The system where most constants are 1 has clearly an advantage. Maybe I
> > will switch to the foot as unit of length if you define it as the length
> > travelled by the light in 1 nanosecond :-)
>
> The meter is defined by a certain odd decimal of the number of wavelengths
> of the yellow light of the singly ionized cessium atom. It does not even
> work out to an even number of wavelengths. Have at it.
>
> The main difference is that the imperial system was devised with access to
> the most number of people that would need it. The SI was devised based on a
> few "standards" that are locked away in a vault or totally inaccessable for
> most people. Actually, all but a few technicians, and very expensive to get
> a direct comparison to those standards.
>
> In contrast, the imperial inch is or was defined as the length of "three
> barleycorns, hard, round and uniform, layed end to end". Anyone can
> duplicate this and come up with a fair approximation. Try that with your
> light apparatus. As a secondary standard, the yard was defined as "The
> distance from the tip of his imperial index finger to the end of his royal
> nose", again, something that is quite easy to approximate, unlike the
> changes in state of an ionized atom, in a vacuum. All of the SI units
> require another SI unit to relate to, and all of them require laboratory
> standards to even approximate.
>
Of course accurate and approximate definition have not the same ease of use
neither the same precision. For the common usage we all can go to the next
store and buy a ruler or ribbon with markings in millimeters or fractions of
inch or both with a sufficient precision. I know that one meter is the
distance from my left shoulder to the end of the middle finger of my right
end when my right arm is horizontally extend, so there is no neesd to disturb
His Imperial Majesty. And in the "developped" world where peasants are becoming
a minority, who knows how to find three barleycorns, hard, round and uniform,
or even how to recognize them (not me). I bet there is also some precise
definition of the imperial units somewhere.
> But, as Lester pointed out, when it comes to human errors, no one system is
> immune. Two factors go against the conversion of the US to the SI, the
> first is cost, and the second is confusion. I use both if I have to, but
> when someone wants something done to SI standards, it costs more. I have to
> convert the numbers into the units of my instruments. Arguing that one
> standard is better than another is ridiculous, none have any advantage over
> what the person using it is familiar with.
>
But even without SI, you have to convert feet to miles, yards to fathoms,
gallons to cubic inches or feet, tons to ounces, psi to inches of Hg and so on.
Of course this may be a vast source of exercises for pupils in the school, but
their time would be better used to learn others things if this became unneeded.
In fact everybody in the world seems to have understood that this has a cost
that only the richest nation in the world can afford.
Greybeard
>
> To discover that there was no good soaring conditions in those lands.
Who cares?
>
> > the Russians Landed the Venera probes on Venus,
>
> with the conclusion that Janus is better than Venus for soaring.
Not the one that I'm familiar with, no atmosphere there.
>
> > and the french are watching the
> > cheerleaders from the sidelines. Don't open that can of worms, Bert.
>
> I visited La Motte du Caire and I understand why Bert doesn't want to
> go on the Moon, on Mars or on Venus ;-))
>
If you can't find what you're looking for within twenty miles of your home,
it doesn't exist.
My point, we've been pretty successful in what we've attempted to do, with
or without SI, or in spite of it.
Greybeard
Greybeard
Jeremy Harris [RU-UK] <j...@uk.sun.com> wrote in message news:988c4c$pm1
>
> Oh, rubbish. To that level of accuracy, a metre is the _same_ as a yard,
> and a centimetre is the width of your thumbnail.
>
> - Jeremy
Sorry dude, but if you're using that as a standard, I can't accept an error
of 50%. (Just measured my thumbnail.)
Greybeard
Greybeard
> But even without SI, you have to convert feet to miles, yards to fathoms,
> gallons to cubic inches or feet, tons to ounces, psi to inches of Hg and
so on.
And a lot of other units such as the link, chain, rod, furlong, acre, that
only the people that use them have to know.
> Of course this may be a vast source of exercises for pupils in the school,
but
> their time would be better used to learn others things if this became
unneeded.
And twice as long to learn the "intertwinings" of the SI?
> In fact everybody in the world seems to have understood that this has a
cost
> that only the richest nation in the world can afford.
Kuwait?
It may be a cost, but less than a tenth of a percent of what it would cost
to convert everything. When it comes to measuring, the unit of measurement
has nothing to do with the accuracy of the final result. To insinuate that
one system is "more accurate" than another would be like insinuating that
ISO-9000 insures higher quality, which it doesn't. We're comfortable with
our present system, it has served us well.
Greybeard
Ged Mcknight
Well here in the UK the Goverment in its infinite wisdom has decided we will all go metric, except typical Labour the steering comittee has decided to go slowly on this
INCH BY INCH
But in reply to the origional posting we have just acquired a new Skylaunch winch and regurlar launch heights are up by over 10-15% on the heights we were used to with our tost.
==============================================================
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Robert Ehrlich
> ..
> It may be a cost, but less than a tenth of a percent of what it would cost
> to convert everything.
Cost of not switching to SI is permanent, cost of switching is only once.
So id you wait a sufficently long time, cost of not switching will be
higher than anything.
> When it comes to measuring, the unit of measurement
> has nothing to do with the accuracy of the final result.
Nobody said anything in contrdiction with this.
> To insinuate that one system is "more accurate" than another would be like
> insinuating that ISO-9000 insures higher quality, which it doesn't.
I completely agree concerning ISO-9000. It only implies that, low or
high quality, what you do is written somewhere, and since the time you
spend to write everything could be better used to improve quality, this
merely implies that quality has some chances to be lower.
F.L. Whiteley
"Bruce Hoult" <br...@hoult.org> wrote in message
news:bruce-47CBCD....@news.nzl.ihugultra.co.nz...
> In article <OwNo6.311$AG3....@news.uswest.net>, "Bill Daniels"
> <wdan...@uswest.net> wrote:
>
> > These 2000' AGL plus winch launches points up that fact that winches,
> > properly designed and operated, are a serious way to get airborne.
Winch
> > launches to these altitudes provide about the same opportunity to find
> > thermals as an airtow since most airtow launches are to about the same
> > altitude and the glider releases near the airfield anyway.
>
> Winches are great, but 2000 ft over the end of the airfield is only
> worth about the same as 1500 ft from a typical towplane that puts you in
> the general direction of the lift.
>
> That's often enough, but not always -- good thing winch launches are
> cheap.
>
With my old Open Cirrus, I could count on one hand the number of times I
took a second launch during a season (UK). That site produced 1600-1700ft
most days. Much better than the 850ft I was used to at the site where I
learned to winch launch, but relished the fact that five hour flights
resulted from 50p launches.
More recently (different location) when we've used the winch locally, if it
was soarable, about 3/4 of the launches committed soaring (including the
2-33).
Personally, I think the only thing that really matters to private owners is
launch rate. But the expense of aero tows also means (in this locale) that
they tend to tow higher than necessary because of the expense of a re-light,
so the launch rate gets pretty miserable (4-5 per hour) at the best time of
day. When you have several ships competing for that 1PM launch window (when
it's been soarable since 11AM but they didn't try due to mindset) it causes
enough friction to reduce the enjoyment. Winch pilots know how to get away,
it's called patience.
Running both side by side is the best of both worlds. I've dangled a check
out the clear vision panel more than once when a private tow plane popped in
for fuel and I was four or more deep in the winch queue. But overall, what
Bill Daniels mentions is that given a well run operation, winches will out
perform tow planes in terms of vertical feet any day. However, site
location is, of course, the most worthwhile decision ever taken for a
soaring site.
All out,
Frank Whiteley.
Lester Hawksby
> and a centimetre is the width of your thumbnail.
- Lester
Gene Nygaard
wrote:
Neither 2 nor 4 of anything--and not even twice as much in one
dimension as in the other.
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
Gene Nygaard
<lh0...@bristol.ac.uk> wrote:
>> But as I think US citzens are rational people, I
>> think that soon or later they will recognize the advantage of a logical
>and
>> uniform system of measurement and switch to it.
>I beg to differ. The unit definitions in SI are completely and utterly
>arbitrary. It certainly can't claim the title logical. Kilograms are just as
>arbitrary as pounds (a kilogram is not, in fact, the mass of a litre of
>water blah blah blah. It's a bit less than that. It is in fact defined as
>the mass of the International Standard Kilogram, a metal block in Paris).
>Metres are just as arbitrary as yards (1/10000000 of an incorrect
>measurement of some part or other of the earth?
And you were standing on the sidelines cheering earlier in the thread
when someone was telling us how nautical miles are the cat's meow,
weren't you?
A kilometer is to a centigrade as a nautical mile is to a minute of
arc.
>Some bloody awkward number
>of radiation wavelengths? Logical?).
Not for over 17 years.
Besides, what's a yard, and the feet and inches based on it? Exact
fraction of a meter, so they were also some "bloody awkward number of
radiation wavelengths," before they became some really awkward
fraction of the speed of light in 1983 (and neither that fraction nor
its inverse is even a terminating decimal number, it will extend on
forever, repeating after a fairly large number of digits.)
>
>As for uniformity: All unit systems will just give different constants. None
>has any advantage there.
Show me an _official_ definition of a pound force.
The biggest disadvantage of the English customary units is their
ambiguity, same names for different units.
What is the difference between the units used for an ounce of
platinum, and an ounce of iridium, the two metals used in the standard
kilogram?
What is the difference between the units for an ounce of tomato juice
and an ounce of ketchup?
What is the difference between the units for an ounce of evaporated
milk and an ounce of sweetened condensed milk.
What is the difference between the pounds used for 20 pounds of
potatoes and the pounds used for 20 pounds per square inch of pressure
in your tires?
If the International Space Station is 240 miles above the surface of
the earth, how many feet (or meters) is that? (You need more
information--I can show you measurements in unidentified miles, of
both kinds, for this purpose).
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
Gene Nygaard
wrote:
>
>Robert Ehrlich <Robert....@inria.fr> wrote in message
>news:3AA76A41...@inria.fr...
>>
>> The system where most constants are 1 has clearly an advantage. Maybe I
>> will switch to the foot as unit of length if you define it as the length
>> travelled by the light in 1 nanosecond :-)
>
>The meter is defined by a certain odd decimal of the number of wavelengths
>of the yellow light of the singly ionized cessium atom. It does not even
>work out to an even number of wavelengths. Have at it.
It was once officially defined based on an orange-red light from
kypton atoms. An unofficial standard based on red light from cadmium
atoms. I have never heard anything about yellow light from cesium
atoms.
None of them is the current definition. It is now (since 1983) defined
so that the speed of light is exactly 299.792 458 Mm/s.
Of course, since before the last two changes in the fundamental
definition of the meter, the yard has been defined as an exact
fraction of a meter. In the U.S., yards and feet and inches have been
exact fractions of a meter for 108 years (the fraction changed in
1959, when the major countries using English units agreed on a common
definition).
>
>The main difference is that the imperial system was devised with access to
>the most number of people that would need it. The SI was devised based on a
>few "standards" that are locked away in a vault or totally inaccessable for
>most people. Actually, all but a few technicians, and very expensive to get
>a direct comparison to those standards.
How do you know when you have a "pound" of something, even if you know
which of several pounds you are talking about and which quantity they
are being used to measure? What is the standard for those pounds.
Where is it kept, and who maintains it?
Only one SI standard is currently locked away in a vault. That
standard also defines both the pounds which are the English mass
standards, avirdupois and troy, and are part of the definition of
other units such as pounds force.
>In contrast, the imperial inch is or was defined as the length of "three
>barleycorns, hard, round and uniform, layed end to end". Anyone can
>duplicate this and come up with a fair approximation. Try that with your
>light apparatus.
An inch is now exactly the distance that light will travel in a vacuum
in 127/1498962290000 s.
>As a secondary standard, the yard was defined as "The
>distance from the tip of his imperial index finger to the end of his royal
>nose", again, something that is quite easy to approximate, unlike the
>changes in state of an ionized atom, in a vacuum. All of the SI units
>require another SI unit to relate to, and all of them require laboratory
>standards to even approximate.
>
>But, as Lester pointed out, when it comes to human errors, no one system is
>immune. Two factors go against the conversion of the US to the SI, the
>first is cost, and the second is confusion.
The confusion is rampant, though usually unrecognized, in even
figuring out which customary unit is being used.
Most Americans don't understand much of anything about the customary
units of measure. They are just comfortable-sounding old words. I
doubt that half could even tell you with any certainty how many quarts
there are in a gallon (teaching of word roots isn't what it used to be
either). That's assuming the quarts and gallons are in the same
system; I wish I had a nickel for every time I've heard that there are
5 quarts in a Canadian gallon, though it contains neither 5 imperial
quarts nor 5 U.S. liquid quarts nor 5 U.S. dry quarts.
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
But if it be thought that, either now, or at any future time, the
citizens of the United States may be induced to undertake a thorough
reformation of their whole system of measures, weights and coins,
reducing every branch to the same decimal ratio already established
in their coins, and thus bringing the calculation of the principal
affairs of life within the arithmetic of every man who can multiply
and divide plain numbers, greater changes will be necessary.
U.S. Secretary of State Thomas Jefferson, 1790
Bill Daniels
>
> "Bruce Hoult" <br...@hoult.org> wrote in message
> > Winches are great, but 2000 ft over the end of the airfield is only
> > worth about the same as 1500 ft from a typical towplane that puts you in
> > the general direction of the lift.
> >
Bruce makes a valid point, although I think the opportunity difference is
more like 2-300' in favor of air tow. I feel pretty good about my chances
of soaring away from a 2000' winch launch if conditions are such that a
2000' air tow would be soarable.
However, if the winch can be made to deliver 300 - 500 feet more altitude,
say 2500' reliabily, then the winch is the better choice. I think spectra
can deliver this height advantage over steel wire.
"F.L. Whiteley" <gre...@greeleynet.com> wrote in message
news:Tdkq6.576$T3.189...@news.frii.net...
>
> Personally, I think the only thing that really matters to private owners
is
> launch rate. But the expense of aero tows also means (in this locale)
that
> they tend to tow higher than necessary because of the expense of a
re-light,
> so the launch rate gets pretty miserable (4-5 per hour) at the best time
of
> day. When you have several ships competing for that 1PM launch window
(when
> it's been soarable since 11AM but they didn't try due to mindset) it
causes
> enough friction to reduce the enjoyment. Winch pilots know how to get
away,
> it's called patience.
This is a very good point. If you are at the end of a 5 deep air tow queue,
and the tow rate is 5 per hour, there is the loss of an hours worth of
soaring. If a multi reel winch can reliably deliver 16 launches per hour to
2500' I sure know which I would prefer. I think that it will come down to
this.
Bill Daniels
Robert Ehrlich
> ...
> The main difference is that the imperial system was devised with access to
> the most number of people that would need it. The SI was devised based on a
> few "standards" that are locked away in a vault or totally inaccessable for
> most people. Actually, all but a few technicians, and very expensive to get
> a direct comparison to those standards.
One of the objecives of the creators and promoters of the original metric system
was that it becomes accesible to the most number of people that would need it.
In order to meet this objective, markings for the length of 1 meter were put on
the walls of several houses. Most of them don't exist any more but one of them
is still visible on a house at the Place Vendome in Paris. Of course, due both
to the initial inaccuracy of this marking and the evolution of the definition
of the meter, it is wrong of a few millimeters.
Lester Hawksby
> when someone was telling us how nautical miles are the cat's meow,
> weren't you?
tthe entire thread. I quite like nautical miles, though. Not really familiar
with them, but they're just as good as any other similar measure.
> A kilometer is to a centigrade as a nautical mile is to a minute of
> arc.
Pardon?
> Besides, what's a yard, and the feet and inches based on it? Exact
> fraction of a meter,
1 yard was originally 108 hard, round, uniform barleycorns laid end to end.
Then it was a succession of standard rods. Borrowing someone else's (the
metre) was just cheaper than making a new one. It could just as easily be
done the other way 'round.
> so they were also some "bloody awkward number of
> radiation wavelengths," before they became some really awkward
> fraction of the speed of light in 1983 (and neither that fraction nor
> its inverse is even a terminating decimal number, it will extend on
> forever, repeating after a fairly large number of digits.)
If it repeats, it's expressible accurately as a fraction.
A friend of mine suggests we measure in attoparsecs in order to avoid nasty
constants. (A attoparsec is about 3.08cm)
> Show me an _official_ definition of a pound force.
IIRC I have it in print at home somewhere. I'll have look when I'm next
there.
> The biggest disadvantage of the English customary units is their
> ambiguity, same names for different units.
OK. Of your examples, two are a simple case of fluid measure versus dry
measure. Easy enough given that we have quite enough other units to choose
from. I admit that the precious metals thing is a bit odd, but it must just
have evolved to serve a different set of needs, which is fair enough.
The pounds in PSI and in potatoes are the same thing, both being a force
unit. It's equivalent to going out and buying potatoes in Newtons. Sounds
odd until you remember that those potatoes have been weighed on a scale by
means of the force of gravity acting upon them, so using just saves a
little bit of multiplying by g. I could buy potatoes by the slug if I wanted
to, anyway. In theory, anyway.
> If the International Space Station is 240 miles above the surface of
> the earth, how many feet (or meters) is that?
Something like 1,267,200 of the mile we actually *use*, if my slide rule is
straight. I can think of an awful lot of alternatives, but most of them are
either arcane and archaic (I mean, you can have it in Roman miles if you
want...) or specialist (nautical).
Congratulations! You have been trolled!
- Lester Hawksby
Richard Brisbourne
<lh0...@bristol.ac.uk> writes
>> Show me an _official_ definition of a pound force.
>IIRC I have it in print at home somewhere. I'll have look when I'm next
>there.
>
<pedantry>
fps unit of mass: pound.
fps absolute unit of force: poundal (force required to accelerate 1
pound mass by 1 ft/sec/sec.
fps gravitational unit of force: pound weight (force required to
accelerate 1 pound mass by 1g (32 ft/sec/sec).
(the astute will notice that 1 pound weight is the "normal" downward
force on a 1 pound mass due to gravity).
</pedantry>
>The pounds in PSI and in potatoes are the same thing, both being a force
>unit. It's equivalent to going out and buying potatoes in Newtons. Sounds
>odd until you remember that those potatoes have been weighed on a scale by
>means of the force of gravity acting upon them, so using just saves a
>little bit of multiplying by g. I could buy potatoes by the slug if I wanted
>to, anyway. In theory, anyway.
Oh no, they're not. The pounds in psi are actually shorthand for pounds
weight. The pounds in potatoes are a unit of mass (see above).
Perfectly logical since the traditional way of buying them is weighed on
a balance against a standard weight of 1 pound mass.
All of which I'm old enough to have learned in school. And my job keeps
me alert to clever Americans who can get 55 gallons in a 45 gallon drum,
and gliding with coping with how the 12 stone pupil stacks up against a
190 lb limit in the front cockpit. As has been pointed out before, speed
in knots, height in feet, distance in kilometres.
Who's going to be first round a 150 nautical mile triangle in under 200
kilofurlongs/fortnight?
--
Richard Brisbourne
Gene Nygaard
<lh0...@bristol.ac.uk> wrote:
>> And you were standing on the sidelines cheering earlier in the thread
>> when someone was telling us how nautical miles are the cat's meow,
>> weren't you?
>I wasn't really watching. I only dropped in and didn't read back through
>tthe entire thread. I quite like nautical miles, though. Not really familiar
>with them, but they're just as good as any other similar measure.
>
>> A kilometer is to a centigrade as a nautical mile is to a minute of
>> arc.
>Pardon?
Like the nautical mile, the meter was originally based on the Earth.
Consider those other units you can use for trig functions on most
calculators, other than degrees and radians. The ones misnamed
"gradients" on the calculator that comes with Windows.
They are actually grads or grades, and another synonym now is gon. An
angle of 1 grad or grade at the center of the earth subtends an arc of
100 km on the surface; or 1 centigrade subtends 1 kilometer.
When I was in the U.S. Army nearly 30 years ago, our maps had tick
marks for the latitude and longitude in grads.
>
>> Besides, what's a yard, and the feet and inches based on it? Exact
>> fraction of a meter,
>1 yard was originally 108 hard, round, uniform barleycorns laid end to end.
>Then it was a succession of standard rods. Borrowing someone else's (the
>metre) was just cheaper than making a new one. It could just as easily be
>done the other way 'round.
>
>> so they were also some "bloody awkward number of
>> radiation wavelengths," before they became some really awkward
>> fraction of the speed of light in 1983 (and neither that fraction nor
>> its inverse is even a terminating decimal number, it will extend on
>> forever, repeating after a fairly large number of digits.)
>If it repeats, it's expressible accurately as a fraction.
>
>A friend of mine suggests we measure in attoparsecs in order to avoid nasty
>constants. (A attoparsec is about 3.08cm)
>
>> Show me an _official_ definition of a pound force.
>IIRC I have it in print at home somewhere. I'll have look when I'm next
>there.
>
>> The biggest disadvantage of the English customary units is their
>> ambiguity, same names for different units.
>OK. Of your examples, two are a simple case of fluid measure versus dry
>measure. Easy enough given that we have quite enough other units to choose
>from.
But how many people realize that neither ketchup nor sweetened
condensed milk are sold by fluid measure? Or that fluid ounces in the
U.S. are different from Imperial fluid ounces?
>I admit that the precious metals thing is a bit odd, but it must just
>have evolved to serve a different set of needs, which is fair enough.
What's really strange here is that Great Britain outlawed the troy
pound in the 19th century (something that was never done in the U.S.),
yet the U.K. today in 2001 has a special exception to its metrication
laws to provide for continued use of the troy ounce.
>The pounds in PSI and in potatoes are the same thing, both being a force
>unit.
No, the pounds used for potatoes are mass units.
>It's equivalent to going out and buying potatoes in Newtons. Sounds
>odd until you remember that those potatoes have been weighed on a scale by
>means of the force of gravity acting upon them, so using just saves a
>little bit of multiplying by g. I could buy potatoes by the slug if I wanted
>to, anyway. In theory, anyway.
Much better theory than using newtons, since both the pounds and the
kilograms used for this purpose are units of mass.
If you weigh them on a balance (the only type of weighing device
available before what, the middle of the 18th century or later?), then
you would need to know g and multiply by it if you wanted to get
force. That isn't what we want so the balance works fine as it is.
Today, the electronic load cell scales that are taking over for this
purpose are inherently force measuring devices, but microprocessors
now make it fairly easily to program them to measure mass in situ.
When they are used in commerce, that is how they or their resulting
measurements are tested and certified, based on their accuracy in
measuring mass in the location in which they are used, not their
accuracy in measuring force.
>> If the International Space Station is 240 miles above the surface of
>> the earth, how many feet (or meters) is that?
>Something like 1,267,200 of the mile we actually *use*, if my slide rule is
>straight.
You're better than I am, if you can get that many digits from your
slide rule.
But that would only be true if the miles are the miles that the NASA
Media Relations office often uses in reporting these altitudes to the
public. If it was instead the miles the NASA scientists use, it would
be 1458268 ft, which would round to 1460000 ft.
>I can think of an awful lot of alternatives, but most of them are
>either arcane and archaic (I mean, you can have it in Roman miles if you
>want...) or specialist (nautical).
Like someone else said, only American rocket scientists would use
nautical miles for a vertical distance. They do.
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
Lester Hawksby
like that.
> Consider those other units you can use for trig functions on most
> calculators, other than degrees and radians. The ones misnamed
> "gradients" on the calculator that comes with Windows.
> They are actually grads or grades, and another synonym now is gon. An
> angle of 1 grad or grade at the center of the earth subtends an arc of
> 100 km on the surface; or 1 centigrade subtends 1 kilometer.
At least in angle measurement there is a genuinely logical unit: the radian.
Pity it's about as compatiable with calculators as "string measurement" of
lengths is (as in, "how long is a piece of string").
> When I was in the U.S. Army nearly 30 years ago, our maps had tick
> marks for the latitude and longitude in grads.
Presumably those won't go neatly into degrees, though?
> Or that fluid ounces in the
> U.S. are different from Imperial fluid ounces?
In general, mostly only Brits know that. I know mostly because of seeing
both on measuring cylinders.
> If you weigh them on a balance (the only type of weighing device
> available before what, the middle of the 18th century or later?), then
> you would need to know g and multiply by it if you wanted to get
> force. That isn't what we want so the balance works fine as it is.
The pound I have conversion figures for right here claims to be weight. Most
old Brits I know claim that the pound is a weight unit. Maybe you Americans
are different. I can't see why, though. I should look this up on the web
somewhere, I suppose.
> You're better than I am, if you can get that many digits from your
> slide rule.
Yeah, I would probably have got 1,270,000 if I'd done the calculation
normally. But it is none too difficult to split the calculation up and then
add back together at the end for accuracy. Slow at first but you get fast
eventually. It's ludicrous, really - here I am sitting in front of a machine
capable of umpty thousand calculations a second, probably doing more raw
calculation in a minute than I will do in a lifetime just to keep Outlook
running, but my windows calculator is broken. And anyway, the ruler gives me
geek cred, and scares my fellow students, who've mostly never seen one used
before in their lives :-)
> But that would only be true if the miles are the miles that the NASA
> Media Relations office often uses in reporting these altitudes to the
> public. If it was instead the miles the NASA scientists use, it would
> be 1458268 ft, which would round to 1460000 ft.
> Like someone else said, only American rocket scientists would use
> nautical miles for a vertical distance. They do.
Yeah, well, they're NASA. The distance between NASA's Media Relations people
and their scientists can't be measured in any form of miles. Or even
kilometres.
We seem to have gone even further off topic. I think I'll stop now.
- Lester
Gene Nygaard
<lh0...@bristol.ac.uk> wrote:
>> Like the nautical mile, the meter was originally based on the Earth.
>Yeah, one ten millionth of the distance from pole to equator or something
>like that.
>
>> Consider those other units you can use for trig functions on most
>> calculators, other than degrees and radians. The ones misnamed
>> "gradients" on the calculator that comes with Windows.
>> They are actually grads or grades, and another synonym now is gon. An
>> angle of 1 grad or grade at the center of the earth subtends an arc of
>> 100 km on the surface; or 1 centigrade subtends 1 kilometer.
>At least in angle measurement there is a genuinely logical unit: the radian.
>Pity it's about as compatiable with calculators as "string measurement" of
>lengths is (as in, "how long is a piece of string").
>
>> When I was in the U.S. Army nearly 30 years ago, our maps had tick
>> marks for the latitude and longitude in grads.
>Presumably those won't go neatly into degrees, though?
Multiply by 0.9.
>> If you weigh them on a balance (the only type of weighing device
>> available before what, the middle of the 18th century or later?), then
>> you would need to know g and multiply by it if you wanted to get
>> force. That isn't what we want so the balance works fine as it is.
>The pound I have conversion figures for right here claims to be weight.
That doesn't tell you whether it is a mass unit or a force unit.
>Most old Brits I know claim that the pound is a weight unit. Maybe you
>Americans are different. I can't see why, though. I should look this
>up on the web somewhere, I suppose.
Weight is an ambiguous word. It entered the English language over
1000 years ago to mean the quantity measured with a balance. That
quantity is mass, not force.
That is and always has been the weight of commerce. That's as it
should be, too. We want to know how much stuff we have, not how hard
it is pressing down on the table or whatever. We don't want this
"weight" to vary with location.
In many, but not all, scientific applications, a different definition
of weight is used, for the force due to gravity. Then there's also
the archers who use it for a different kind of force when they talk
about the draw weight of their bows.
When you think of the pound as a unit of weight, think of the troy
pound. In the troy "system of weights" the units are always units of
mass, never units of force.
All the pounds used throughout history at various places were mass
units. Only the avoirdupois pound has spawned a force unit of the
same name.
1 lb = 0.45359237 kg (exactly, by definition)
1 lbf = 4.44822 N
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
Nyal Williams
> news:3AA4D9...@sympatico.ca...
> > Greybeard wrote:
> > >
> > > And most european glider pilots are used to using the units, which
> almost
> > > all US glider pilots would find confusing.
> >
> > Untrue !
>
> I went through the "metric conversion" at my work, don't tell me it isn't
> confusing. Suddenly, we didn't have any 3/4 inch shafting anymore, but
inch
> shafting either, 25.40 mm. I now work in my own units, the "Pitlar".
> Stands for Ph*** It, That Looks About Right.
It'll be a LONG time before we get standardized; most likely will require
re-writing of all tables of strengths, etc. that engineers use. Can that
19.05mm possibly be reduced to 19mm without structural danger? (I'm no
engineer.)
I note that our notion of normal body temperature is 98.6F. That seems to
be very precise, but it is nothing more than an arithmetic conversion of 31
Cent., which was established on the Continent as the normal body
temperature. We have the same problem in converting recipes from or to the
continentental measuring systems. Conversions wind up with all sorts of
precise fractions that are not warranted in the originals.
Measuring flour, bolt shaft shear strength, sheet aluminum thickness
strength? There has to be enough margin to account for different batches of
material and this allows enough fudge factor that the recipes and the tables
of strength can always be stated in gross measurements.
Anyone disagree? My training is in music history; I could be WAY of base!
KeithW
"Nyal Williams" <nyalwi...@home.com> wrote in message
news:AoKt6.124432$t67.1...@news1.rdc1.il.home.com...
>
> "Greybeard" <grey...@mwci.net> wrote in message
> news:taa6l66...@corp.supernews.com...
> >
> > Jean Richard <j.ri...@sympatico.ca> wrote in message
> > news:3AA4D9...@sympatico.ca...
> I note that our notion of normal body temperature is 98.6F. That seems to
> be very precise, but it is nothing more than an arithmetic conversion of
31
> Cent., which was established on the Continent as the normal body
> temperature. We have the same problem in converting recipes from or to
the
> continentental measuring systems. Conversions wind up with all sorts of
> precise fractions that are not warranted in the originals.
>
Principle is correct, but figures appear incorrect. I get 37 when I do
(98.6-32)*5/9. Chance of 19.0mm being inadequate if 19.05mm is ok is
minimal, but 'correct ' metric unit would be a round number - possibly 20?
Keith
Greybeard
KeithW <du...@btinternet.com> wrote in message
news:998hv2$3hs$1...@plutonium.btinternet.com...
>
> Chance of 19.0mm being inadequate if 19.05mm is ok is
> minimal, but 'correct ' metric unit would be a round number - possibly 20?
>
metric size. The difference between 19 and 19.05mm is comparing .748 inches
to .750. Unless it was a press fit or in a bearing, there aren't too many
people that would notice.
Greybeard
gerald clark
Actually, Farenheit chilled it with ice and salt to get the coldest
attainable in the laboratory, and called it 0.
Then he stuck it in his mouth, and called it 100. He was running a
little warm that day.
> Measuring flour, bolt shaft shear strength, sheet aluminum thickness
> strength? There has to be enough margin to account for different batches of
> material and this allows enough fudge factor that the recipes and the tables
> of strength can always be stated in gross measurements.
>
> Anyone disagree? My training is in music history; I could be WAY of base!
--
Member: Sky Soaring
Illinois, U.S.A.
valerio...@gmail.com
> Curious what the highest sailplane launch from a winch has ever been for the
> longest cable.
>
> Michael
At the Reinsdorf Airfield whinch launches with 2,600m (8500ft) cable are possible. As long as I know, the record was a ASK-21 to 1380m (4500ft).
Bruce Hoult
I note that back then I said:
> Winches are great, but 2000 ft over the end of the airfield is only
> worth about the same as 1500 ft from a typical towplane that puts you in
> the general direction of the lift.
Flying in the back seat with other qualified pilots at the controls it's amazing how many people hold on to the tow straight through monster thermals at 1000 ft simply because they're fixated on their pre-flight notion to tow to 2000, 2500 or whatever. Or maybe don't yet have the surplus mental bandwidth in that aircraft to follow the towplane in active conditions and also at the same time keep an eye on the vario.
I know I was like that myself once, and only got woken up from it one day on a site check in a Grob at Omarama when the top competition pilot/CFI in the back seat asked me why I didn't take the booming thermal we just flew through. All I could think about was slack line recovery after the towplane was suddenly 50 ft below me -- not ask *why* the towplane was suddenly plummeting.
AS
https://www.youtube.com/watch?v=R1uC0lFVXNU
https://www.youtube.com/watch?v=-Dw6r_1r91M
https://www.youtube.com/watch?v=oyRlkOgkZho
We (Carolina Soaring Assoc.) do achieve anywhere between 1,300-2,100ft using our home built winch powered by a mildly hopped-up Ford 460 engine and 4,300ft of Spectra. Wind and pilot skills have a strong influence on the resulting release height.
Uli
herbk...@gmail.com
Things are a bit different when ballasted, but only a bit.
roel.b...@gmail.com
AS
I am with Roel.b: Aerobatic pilots and students need high launch altitudes to keep cost down! ;-)
chip.b...@gmail.com
Chip Bearden
Frank Whiteley
> Aerobatic pilots need altitude. The pilots of Weelde were aerobatic glider pilots.
https://www.youtube.com/watch?v=-Dw6r_1r91M ~1450m in 2 minutes. Record of 1740m was done in 2007 with run of 3000m.
IIRC, the winch (not the mel ad video) that was used in the record 1700m launch and some launches
https://www.youtube.com/watch?v=zFKsjDIjmDg&list=PL7DF0FF821E223010
Check out this first solo and her video
http://www.northdevongazette.co.uk/news/torrington_schoolgirl_14_on_cloud_nine_after_historic_first_solo_glider_flight_1_4797335
Frank Whiteley
Tom BravoMike
> Curious what the highest sailplane launch from a winch has ever been for the
> longest cable.
>
> Michael
Achieved height: 1852m (6076 feet)
Rope length: 4100m
Source (in Polish, with pictures, including the altimeter):
http://lotniczapolska.pl/Milowa-wysokosc-holu-za-wyciagarka-szybowcowa-BB-Aero-w-Bialej-Podlaskiej,39116
Tom
herbk...@gmail.com
firsys
> Curious what the highest sailplane launch from a winch has ever been for the
> longest cable.
>
> Michael
As I read the altimeter, they reached 2500m; however maybe
the airfield is 630 m ASL.
what cable material do they use? Spectra?
The amusing thing is the inverted slip indicator!
JMF
Tom BravoMike
What you should be looking at is the third big photo in the article: the altimeter is showing 1850m. The one you mention is actually 250m,apparently on a long final. As Poland is mostly flat, at many airfields the glider pilots set the altimeters to 0m. IMO, combined with the 'strange' location of ZERO at the bottom of the dial, that helps a lot in visualizing the gain or loss of height in those critical 500m over the field elevation. You launch, and the pointer hand goes up, just as you do. And vice versa.
They don't seem to mention the cable material in the article. Maybe somebody reading this group in Poland can answer.
Tom
Tom BravoMike
https://pl.wikipedia.org/wiki/L%C4%85dowisko_Bia%C5%82a_Podlaska
Tom
kirk.stant
>
> Number of aerobatic glider pilots in the Chicagoland area (4 clubs including Beloit WI) is exactly Zero. High tows, who needs them?
Take a high tow then spend a few exhilarating minutes pulling G's and making the world go around - you just haven't lived until you have looked up at the ground from the top of a loop, or felt that moment of stillness at the apex of a hammerhead (stall turn) when there is just the silent rotation of your glider before it accelerates back straight down...
You guys have K-21s, don't you? Use them!
Seriously - if you have the opportunity to take an acro course - do it; it will open up a whole new way to enjoy gliders, and improve your flying skills.
Kirk
66
Have enjoyed acro in a variety of gliders including G-103 Acros, K-21s, 2-32s, 1-26s, L-13ACs and an incredible Swift S-1 (9G's on that one!!!). Oh, and maybe a little in my LS6... ;^)
Dan Marotta
cloverleafs but stall it in landing configuration and you got to
practice your spin recovery techniques! Oh, and it was terrific on
ground launches though I never had a chance to use so much rope.
Dan
5J
Dan, 5J
herbk...@gmail.com
Herb
kirk.stant
> Kirk, of course you are right. My statements were somewhat tongue-in-cheek to expose the habit of taking high tows for no good reason. I enjoy the ~5sec of Zero-g that you can get from a well-flown hammerhead stall and we spin our ASK-21's regularly during flight reviews and in student training (with tail weights). So go, take the 3,500' aero-tow, your club treasurer will be thankful.
> Herb
Has there been any interest in a glider acro program in your parts?
Kirk
66
herbk...@gmail.com
Herb J7
m4l...@gmail.com
> Curious what the highest sailplane launch from a winch has ever been for the
> longest cable.
>
> Michael
Best straight launch is about 2,300'.
Don Johnstone
weight of that amount of cable would be around 1400lbs. 5mm cable
would be 2180lbs, pretty close to a ton. That is all supported by the
frame to which the release is mounted, and of course the wing roots. If
the T21 had a GoG hook it is bolted to the frame which supports the
seat. The things we did when we were young and stupid.
Nick Kennedy
Back in the 80's These Texas Hang Glider pilots developed this payout winch Hang Gliding launch system.
I bought a small trailer mounted one, professionally built called Reel Air.
We had a total blast with that thing.
I had 6000' of line on it and we could easily get to over 5000' AGL.
We would go out to Canyonlands in Utah and do incredible flights.
I believe I hold some kind of record on tow.
The winch had a disc brake with pressure regulator on it and we could stop the payout and just drag the Hang Glider along, often times for miles.
One Fall day I took off the Reel Air and started climbing at the north end of Hatch Point road in Canyonlands headed south. My driver paid out about 5800' of rope and "Locked the winch" and kept driving, like all the way to Hwy 191, about 30 miles!
We got alot of great photos in that era.
Unfortunately My HG partner and driver of this tow, Craig Pirazzi, was killed in a blown cliff launch accident a few years back, at the start of this long winch tow point, during a Hollywood film shoot.
Those were the wild days, we had some balls let me tell you!
Tim Newport-Peace
example!
Incidentally, with a 1000lb weak link, which was the norm in those days,
why
did it not break with 2000+lbs of cable suspended?
da...@sculptressfashions.com
Martin Gregorie
> Probably not the best idea in the world. If using 4mm steel cable the
> weight of that amount of cable would be around 1400lbs. 5mm cable would
> be 2180lbs, pretty close to a ton. That is all supported by the frame to
> which the release is mounted, and of course the wing roots. If the T21
> had a GoG hook it is bolted to the frame which supports the seat. The
> things we did when we were young and stupid.
>
winched to 1500m and then doing aerobatics all the way down, but it seems
to have vanished. Took around 2.5 minutes on the winch to get to the top.
One of the videos was shot from the back seat in the Fox and the other
watched the reel on the Tost winch as it steadily filled right up.
IIRC this was connected with an aerobatic comp somewhere in Germany.
--
Martin | martin at
Gregorie | gregorie dot org
br...@utahradonservices.com
https://youtu.be/VrUTjWEfbcI
Cheers!
Bruno - B4
Tango Whisky
Frank Whiteley
I think your napkin calcs need another go. 3/16" (4.75mm) 7/7 galvanized steel wire rope weighs 6.1lbs/100ft. We used 5400ft on our winch run. That weighed 330lbs. We now use 3/16" Amsteel Blue, which weighs 54lbs. So, a glider at our site on a 2000ft launch would be lifting about 125lbs of steel wire rope, plus few pounds of strop and parachute.
4mm-5mm steel would weight a bit more or less, but nothing like what you've calculated. Something got inverted in your calcs.
Frank Whiteley