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Gravity launch



 
 
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  #1  
Old October 4th 03, 11:25 PM
Mark James Boyd
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Default Gravity launch

I'm wondering if anyone regularly rolls gliders
down a cliff for launch.

I was thinking that a suitable slope off the edge of a cliff
would work just as well as any tow/winch/auto/bungee/rotax.
And if there is reliable lift nearby, you can come back and
land.

I know this is commonly done with hang gliders, but haven't
heard of a location that does this with gliders. Maybe somewhere
in the Sierras or Alps or something like that? Any of you
Europeans heard of something like this regularly used for gliders?
I'm thinking of a place where you launch, then find lift, do some
circles, and then come back and land.



  #4  
Old October 5th 03, 08:51 AM
Mark James Boyd
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Default

In article ,
acrawford wrote:
See:

http://www.alisport.com/photo/movie_eng.mpg


Excellent! At first I thought it was a bunch of PW-5 haters
pushing the thing off a cliff. Then I turned up the sound and
heard it was "slope launching." What a great video! ;-P

As Judy pointed out it's a little sketchy if the slope drops off a cliff.
If something goes wrong (catch a wingtip, etc.), or the glider doesn't
accelerate enough before going over, things might get interesting...

But my god if that isn't the simplist form of launch I can imagine.
Oh, and in the U.S. there is no required "slope launch" endorsement :-)

I'm guessing 500 feet or less of slope that drops 25 feet would
be sufficient (something like a 5%-10% grade).

I'd sure like to find a spot like this in California, USA :-)
Thanks so much for all the feedback...this is quite the
glider brain trust..

Mark Boyd



  #5  
Old October 5th 03, 09:59 AM
tango4
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Excellent!

Ian

"acrawford" wrote in message
om...
See:

http://www.alisport.com/photo/movie_eng.mpg



  #6  
Old October 5th 03, 10:23 AM
Silent Flyer
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Mark James Boyd wrote in message
news:3f7f48f1$1@darkstar...
I'm wondering if anyone regularly rolls gliders
down a cliff for launch.

I was thinking that a suitable slope off the edge of a cliff
would work just as well as any tow/winch/auto/bungee/rotax.
And if there is reliable lift nearby, you can come back and
land.

I know this is commonly done with hang gliders, but haven't
heard of a location that does this with gliders. Maybe somewhere
in the Sierras or Alps or something like that? Any of you
Europeans heard of something like this regularly used for gliders?
I'm thinking of a place where you launch, then find lift, do some
circles, and then come back and land.




At the Midland Gliding Club in the UK they still bungee launch when the
conditions are suitable.

Back in the 70's I regularly launched this way. On one occasion the ring was
not properly inserted into the (recessed) tow hook on my Dart 17r even
though a check indicated that it was. The 6 man launch team stretched out
the bungee ( 3 each side on the Y shape) and I had rolled forward about six
feet when the ring came off the hook. Unable to stop as the glider rolled on
down the rapidly steepening hill, the launching crew threw themselves down
as my wings passed over them. The glider rolled down the hill slowly
accelerating until a bump threw us in the air. With a lot of forward stick I
dived into the valley until it was safe to pull back and climb away in the
lift. The wind on the ridge was probably about 20/25 knots so flying speed
was attained fairly quickly.

Its not something I would like to repeat though.


  #7  
Old October 5th 03, 02:32 PM
Roger Felton
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Check out Mike Sandlin's "Bug" and "Goat" ultralight gliders. He is
regularly doing a rolling launch from the same sites that hang gliders
use. http://home.att.net/~mikesandlin/bug_in_action.htm
http://home.att.net/~m-sandlin/goat.htm

RF

Mark James Boyd wrote:

I'm wondering if anyone regularly rolls gliders
down a cliff for launch.

I was thinking that a suitable slope off the edge of a cliff
would work just as well as any tow/winch/auto/bungee/rotax.
And if there is reliable lift nearby, you can come back and
land.

I know this is commonly done with hang gliders, but haven't
heard of a location that does this with gliders. Maybe somewhere
in the Sierras or Alps or something like that? Any of you
Europeans heard of something like this regularly used for gliders?
I'm thinking of a place where you launch, then find lift, do some
circles, and then come back and land.


  #8  
Old October 6th 03, 05:28 AM
Tomasz Sielicki
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Default

Mark James Boyd napisal(a):

I'm wondering if anyone regularly rolls gliders
down a cliff for launch.

I was thinking that a suitable slope off the edge of a cliff
would work just as well as any tow/winch/auto/bungee/rotax.
And if there is reliable lift nearby, you can come back and
land.

I know this is commonly done with hang gliders, but haven't
heard of a location that does this with gliders. Maybe somewhere
in the Sierras or Alps or something like that? Any of you
Europeans heard of something like this regularly used for gliders?
I'm thinking of a place where you launch, then find lift, do some
circles, and then come back and land.


It has been done regularly (provided proper wind direction&speed) at the
famous Bezmiechowa airfield in southern Poland. In 2001 we went there
with a group of friends from the Aeroklub Poznanski to try it out. The
weather was perfect for the task. 3 days, many, many flights (Bocian,
Puchacz, SZD-55) - GRAVITY LAUNCHES ONLY. No winch, no towplane, no
bungee, no release. See my start in SZD-55;

http://www.aeroklub.poznan.pl/szybow...ez01/bez09.htm

or an animation on a "Bocian"'s launch...
http://www.aeroklub.poznan.pl/szybow...ez01/bez22.htm

or the whole picture story of the expedition starting he
http://www.aeroklub.poznan.pl/szybow...ez01/bez01.htm and
to continue click the 'unvisited' link to the right of the thumbnails...

Note the wind strength on the trees and on the windsock. Just one turn
after being airborne was enough to get higher than the start point and
above the heads of those down on the ground. Unforgettable!

Not to mention the NIGHT RIDGE SOARING from a gravity launch on a
"Bocian"... No kidding.

BTW: Why "the famous Bezmiechowa airfield"? Alone in 1939 about 400
glider pilots were trained there. Check FAI files for pre-war records
flown from Bezmiechowa:

1938-5-18 Tadeusz Gora in a cross country flight between Bezmiechowa
and Wilno achieved distance of 577.8 km in recognition of which FAI
awarded him the first ever Lilienthal Medal.

1937-5-14 Miss Wanda Modlibowska finished her 24h 14 min flight which
set a new duration record.

In the links above, old historic pictures are added to give an idea what
Bezmiechowa used to be until the total distruction in WWII. Slowly being
rebuilt in recent years - very far away from its former glamour.

Tomasz Sielicki


  #9  
Old October 6th 03, 02:53 PM
andre louistisserand
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Default

clic this link :
http://www.alisport.com/photo/movie_eng.mpg

"Mark James Boyd" a écrit dans le message de news:
3f7f48f1$1@darkstar...
I'm wondering if anyone regularly rolls gliders
down a cliff for launch.

I was thinking that a suitable slope off the edge of a cliff
would work just as well as any tow/winch/auto/bungee/rotax.
And if there is reliable lift nearby, you can come back and
land.

I know this is commonly done with hang gliders, but haven't
heard of a location that does this with gliders. Maybe somewhere
in the Sierras or Alps or something like that? Any of you
Europeans heard of something like this regularly used for gliders?
I'm thinking of a place where you launch, then find lift, do some
circles, and then come back and land.





  #10  
Old October 8th 03, 03:32 AM
Wayne Paul
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Default


"Fat Albert" wrote in message
...
Having experienced Bungee launches from several sites in modern (ish)
sailplanes including Dunstable (200ft hill, repeat 200ft) I can confirm

that

" there's only one other thing in life that crams so much sensation into
such a short duration"

What is that? -- a night catapult shot from a 27-Charlie carrier?


 




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