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poor lateral control on a slow tow?



 
 
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  #171  
Old January 6th 11, 10:52 PM posted to rec.aviation.soaring
Gary Osoba[_3_]
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Posts: 32
Default poor lateral control on a slow tow?

On Jan 5, 12:37*am, Doug Greenwell wrote:


Right ... it's the weight opposing the rope pull, because the tug is
doing all the work of raising the glider to a higher altitude *-
difficult to demonstrate without a diagram! *


You might appreciate this thread.

http://groups.google.com/group/rec.a... a98e7c22e1da

-Gary
  #172  
Old January 7th 11, 01:46 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,939
Default poor lateral control on a slow tow?

On 1/6/2011 8:34 AM, Andreas Maurer wrote:
On Wed, 05 Jan 2011 21:22:53 -0800, Eric Greenwell
wrote:


I'd love to see "3-D" perspective view of the wake behind a towplane, as
I doubt I'm visualizing it well.


Have you seen this?
http://www.centennialofflight.gov/es...tex/TH15G5.htm

BTW: Have you already seen this? (starts at 0:55):
http://www.youtube.com/watch?v=__pyxPb6gMc

Note how long the air behind the plane continues to sink after the
plane has passed... and how the wing tip vortices and the downwash
behind the wing interact.


I had not seen any of them. Both were very useful. I wish they had the
video show how the split winglets had changed things.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
  #173  
Old January 7th 11, 03:38 AM posted to rec.aviation.soaring
[email protected]
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Posts: 194
Default poor lateral control on a slow tow?

On Jan 6, 3:35*pm, toad wrote:
Have fun Cookie, but until you teach them to draw force diagrams, you
will have frustrating conversations.

I am a practicing aerodyanmicist, but will refrain from speculation on
the tow conditions discussed here. *But I will suggest to anyone
trying to figure out what the required lift is, that they draw out the
forces in what is known as a force diagram. *Also known as a free body
diagram. *http://en.wikipedia.org/wiki/Force_diagram

In un-accelerated flight, which includes aerotow at a constant speed
and climb rate. All the forces, including gravity must add up to zero.


yeah.........this has really branched into two discussions........the
forces of flight, and why a slow tow is bad.



but force diagrams make it really simple to visualise what is going
on. But on tow, with down wash and vortexes and stuff it is hard to
figure what and where the forces really are.


(remember the discussion on "gravity power"?)

Cookie
  #174  
Old January 7th 11, 06:41 AM posted to rec.aviation.soaring
John Chapman
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Posts: 2
Default poor lateral control on a slow tow?

On Jan 3, 11:11*am, Doug Greenwell wrote:
At 23:11 02 January 2011, John Chapman wrote:

....
At what speed are you using 40deg of flap?

In a descent I would think you are likely to be closer to the tug wake
than in a climb-


Hi Doug, Sorry about my slow response. Anyway, the 40 degrees of flap
was used at a descent on tow speed of about 65 mph. A Cessa 182 with
a lot of flap seems fairly stable in descent at this speed, but
produces a large wake which seems to really affect the short wing SGS
2-33 glider. We have also done the same exercise with a G-103 and an
ASK-21. The glass ships seem more stable on descent behind a full
flap 182. I suspect this is due to the greater wing span. All
gliders seem more controlable behind a Piper Pawnee which does not
need as much flap (20 degrees?) in descent at 65 mph. Cheers, John
Chapman, c 805 402-4238
  #175  
Old January 7th 11, 11:13 AM posted to rec.aviation.soaring
Doug Greenwell
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Posts: 67
Default poor lateral control on a slow tow?

At 18:20 06 January 2011, Andy wrote:
On Jan 6, 9:40=A0am, Doug Greenwell wrote:
At 16:11 06 January 2011, Andreas Maurer wrote:

On Thu, 06 Jan 2011 09:09:39 +0000, Doug Greenwell
wrote:


There's a chapter in Eric Brown's book 'Wings of the Weird &
Wonderful' in which he describes flight tests of the GAL 56 flying

wing
glider in 1946. =A0This was a 28deg swept wing with an aspect ratio

of
5.8
towed by a Spitfire IX* (!!!) to 20000ft (!!). =A0


Coooooooooool.


every tug pilots dream ... wonder what the climb rate was like!





He describes the opposite effect, with a very strong (often
uncontrollable) nose-up pitch on take-off - this was thought to be

due
to
ground effect. =A0In this case the tug span was similar (37ft) to

the
glider
span (45ft), so the wake/wing interaction would be different.


Definitely. I think that the slipstream and the turbulence of that
huge propellor might have an influence, too.


Possibly - he had trouble getting the nose down on landing too.









Interestingly he also reports that the GAL56 could be flown

hands-free
on
the tow - unless the tug slipstream was entered, in which case all
lateral
and longitudinal control was lost. =A0Robert Kronfield was later

killed
spinning this aircraft.


Seems like some gliders actually stabilize themselves behind a tow
plane.


Here's an example of a free-flight test of a space shuttle model

that
flew well in aerotow, but worse in free flight.


Ladies and gents, Great Britains only serious contribution to
spaceflight - the Reliant Shuttle:
http://www.youtube.com/watch?v=3DpJdrlWR-yFM


Andreas


That's a bit unfair ... we did manage one satellite into orbit on

Black
Arrow- Hide quoted text -

- Show quoted text -


What about Skynet? I worked the Skynet 4 program.

Andy

true - I should have one british satellite on a british launcher!

  #176  
Old January 7th 11, 12:08 PM posted to rec.aviation.soaring
Martin Gregorie[_5_]
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Posts: 1,224
Default poor lateral control on a slow tow?

On Fri, 07 Jan 2011 10:13:49 +0000, Doug Greenwell wrote:

true - I should have one british satellite on a british launcher!


Launched in 1971 and its still up there. Its radio was still working in
2006. Its orbit is expected to decay around 2106. Not too dusty for the
second attempt at launching a satellite.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
 




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