Multiple-Simultaneous Glider Aerotows-USA
Culpusa
Dear Friends,
Is there any place in USA where more than one glider is airplane towed aloft at
once? As a regular proceedure, if so, where?
Are there any glidertug pilots or glider pilots out there in USA who have done
this and what is your experience? Relate it please.
The multiple glider launch behind one tug airplane is not an unusual practice
abroad I understand. Is that correct?
In the USA, we have many powerful engined high lift wing tugs like Pawnees.
Are US glider pilots and towplane pilots so klutzy that they cant launch their
gliders two or three at a time for each airplane tug flight?
Is this feasible in US? If not, why not?
Looking forward to hearing from you. I hope this is not as controversial as
bringing up groundlaunch discussion such as autotow in USA.
Dancing on clouds,
Keep it Up!
Jim Culp "USA"
Gainesville FL
Marc Ramsey
"Culpusa" <cul...@aol.com> wrote...
> Is there any place in USA where more than one glider is airplane towed aloft at
> once? As a regular proceedure, if so, where?
>
> Are there any glidertug pilots or glider pilots out there in USA who have done
> this and what is your experience? Relate it please.
It's done fairly routinely at Williams Soaring Center (California). There is a ridge
roughly 25 miles away where the soaring is often a lot better than in the valley
where the gliderport is located. If there are a lot of gliders wanting to make the
hop, it speeds things up a great deal if we go two at a time.
One short rope and one long rope is used, the glider on the short rope is
displaced off to the side. On takeoff the glider on the short rope goes into
high tow, the glider on the long rope goes into low tow. Release is coordinated
by radio, the glider on the short rope always goes first.
I've towed in both the short and long rope position, the long rope is more
disconcerting, as the glider in front seems a lot closer than it really is. It's
been done with pilots of varying experience, without problem. A double tow
is not attempted unless all three pilots are comfortable with flying with each
other.
Marc
--
_____________________________
Marc Ramsey, ma...@ranlog.com
http://www.ranlog.com/ramsey/
BAToulson
(Culpusa) writes:
>The multiple glider launch behind one tug airplane is not an unusual
>practice
>abroad I understand. Is that correct?
Not common but reasonably frequent in the UK.
You need two ropes, one long and one short, both attached at the point of
connection to the tug release. The gliders start side by side but staggered and
maintain that position whilst on the ground by use of rudder.
Once airborn, the glider on the short rope goes into high tow and moves across
behind the tug. The glider on the long rope goes into low tow and also moves
behind the tug and they maintain this configuration during the climb.
At release, the glider on the short rope (high) goes first.
Sounds complex but, in reality, is not too difficult for a capable pilot and
provided the tug is reasonably powerful.
I don't know any club using this method as routine, but it's a good winter
exercise and we have used it for retrieves from good airfields. I've probably
done 15 or 20 dual tows and seen many more with no problems.
Don't try in with Duo Discus' full of water, you might end up going by road!!
Barney
Lincolnshire
UK
Sam Fly
Jim,
I have double towed with Dick Johnson, when we were doing compairson
flights with two Ventus's.. I was on the long rope (two tow ropes tied
together) and Dick on the normal rope... The Normal rope (short one)
lifts off first and then the long rope lifts off, staying to the left
of the wing off the normal rope. The normal rope goes to normal tow
position and the long rope to low tow position.
We made several tows to 12K for flight test of winglets etc.... Easy
to do, but requires some one you are confortable flying formation with
and an L-19 or Pawnee with plenty of power.. Best to not have any
cross wing due to posible drift on initial lift off.
Sam Fly
Peter D. Brown
Culpusa wrote:
> Is there any place in USA where more than one glider is airplane towed aloft at
> once? As a regular proceedure, if so, where?
>
> Are there any glidertug pilots or glider pilots out there in USA who have done
> this and what is your experience? Relate it please.
Jim:
I have had the opportunity to do this several times while
flying out of AirSailing near Reno. The first was a teaching
tow, the others were aero retrieve to get part way home
after a cross country weekend. Both were done under benign
conditions with almost no crosswind on wide runways and
competent pilots (at least the other guy was extremely
competent in our case.) I think its safe to say this is the
only way to conduct double tows. All aircraft had
functioning radios.
Here's the procedure:
The single tow plane used two tow lines of significantly
different length so the gliders were staggered to reduce the
chance of wing tip contact. The American Soaring Handbook
recommends the shortest line should be no less than 250'
and the other at least 75' longer. Some operators believe
that this is hyper conservative but that a minimum of 40'
differential should be used. Personally, I think rope is
cheap and longer ropes easier to fly.
Both gliders were 1-36s but if we had used different
sailplanes, all other things being equal, the lower L/d
would have gone on the shorter rope. Generally, its best for
the less experienced pilot should go on the longer rope. It
gives him an easier tow to fly, less excitement if the short
rope breaks (he's clear), and he has an easier time
maintaining constant visual contact the other glider,
especially after he assumes low tow on the x-c portion of
the tow.
The gliders' outboard wing tips were placed on the runway so
the initial pull from the tow plane caused the outboard wing
tips to drag and hence pull the glider noses away from each
other and away from the runway centerline. If you have wing
runners, they go on the outside. All slack is pulled out of
both ropes before beginning the tow with glider noses
pointed slightly (5 degrees) to outside.
For initial training, I think it may help to position the
planes on the ground well before takeoff to see how much
clearance you will actually have and what the lateral
separation will look like in the air.
Acceleration was slower than usual so it took a bit longest
to get enough airspeed to aerodynamic control but not long
enough to be too exciting. Ground run was longer than with a
single tow but I was surprised at how little deterioration
we experienced in regular flight.
After takeoff, we had no trouble maintaining position in a V
formation, both aircraft assuming and MAINTAINING
staggered high tow positions just outside the tug's wing
tips.
The short rope guy is charged with maintaining position and
the longer rope guy must maintain constant visual contact.
The bigger the rope length differential, the harder it will
be for the short rope glider to see the other guy.
Turns were kept shallow because of speed differential of
the gliders. Turns are also kept shallow to reduce slingshot
effect on outboard glider.
At times, differential slack line will induce a yo-yo effect
on the gliders. Both should dampen with yaw to the outside.
During the turn, the inside glider would be below and the
outside above the towplane BUT both would maintain a
constant position with respect to the towplane's wing tips.
Alternatively, all three aircraft can turn and stay level
but they will not be flying in the same position with
respect to the tug's wing tip in the turn and must reassume
the wing tip position when the turn ends. It may be easier
to do than it is to describe.
Once we were above pattern altitude and transitioning for
the x-c portion of the tow, the short rope glider assumed
high tow position and the long assumed low tow position.
On release, the short rope glider releases first and turns
LEFT, the long rope glider hangs on a bit and then releases
and turns RIGHT and the tow continues straight.
Brief the emergencies!
If the tow hook fails, both gliders need to release the rope
immediately.
If the short rope breaks, the remaining glider can continue
the tow, maintaining a slightly offset position to avoid the
shorter end.
If the long rope breaks, the short rope glider assumes or
maintains high tow position to keep clear of the rope and
releases as soon as practical. Most rope breaks occur at the
ring so its likely the tow plane will be dragging a long
rope you want to avoid.
Double tows are actually fun and not nearly as difficult
for pilots of moderate experience as my description may
imply. I don't think we need to adopt them for general use
but I think they do have a place for aero retrieves.
Pete
Anchorage
Larry Goddard
using a Schweizer hook, seems like there is not room for two rings... and with a
Tost it would be impossible...
If both ropes are "tied" to one ring then another emergency needing immediate
release by both gliders would be a premature release by the tow plane. Then both
gliders would be tethered together with ropes that could easily come over the top of
the lower glider and foul controls...
Would love to try a dual tow sometime though.
Larry
Christopher Nicholas
routine glider launching. I only know of it being done either for aerobatic
displays, for ferrying gliders, or as a technique to practise in case needed
for the other two purposes. Same in other European countries AFAIK.
It has more potential hazards than normal tows and I am not aware of anyone
letting inexperienced pilots try it.
Usual technique for dual tows is one long and one short rope. Each glider
starts offset from the centreline of the tug, to keep the ropes separate.
Short rope glider goes into high tow position, long rope glider goes into
low tow when airborne, all in line.
I have seen pictures of Wilga tug pulling three gliders, one behind and two
out to the sides IIRC, but I don't know how they start or what relative rope
lengths.
Chris N.
Robertmudd1u
Wilga.
It really focuses your attention.
Robert Mudd
Roelant van der Bos
During the performance testing of the DG-1000 they did a double tow with the
DG-1000 and a duo-discus behind a 360 hp pawnee or so. They were towing on a
warm day and they went to 3000 m. !
http://www.dg-flugzeugbau.de/vergleich-duo-e.html
Certainly shows that nothing beats horsepower !
Roelant van der Bos
Thomas Gemmel
Larry Goddard <la...@siriusimages.com> schrieb in im Newsbeitrag:
3A91A4DE...@siriusimages.com...
> Just out of curiosity, how do you attach 2 ropes/rings to the tow plane?
If you're
> using a Schweizer hook, seems like there is not room for two rings... and
with a
> Tost it would be impossible...
>
in Germany, the two ropes are tied together to one ring.................
> If both ropes are "tied" to one ring then another emergency needing
immediate
> release by both gliders would be a premature release by the tow plane.
Then both
> gliders would be tethered together with ropes that could easily come over
the top of
> the lower glider and foul controls...
We had a accident like that a few Years ago in Germany:
While towing a singleseater and a tow seater, the towplane (afaik a Wilga)
released the rope after having some Motorproblems.
Both Gliderpilots failed to release by themselfs. One Glider went to the
right, the other to the left.
Both Pilots plus a passenger get killed.
Thomas Gemmel
Jantar Std. D-9223
Janusz Kesik
ferrying gliders from the outlandings in the other airfields or when going
to the contest site. The towplane (usually Wilga, as we have only few Zlin
towplanes except Wilgas, Yak-12's and, Gawrons only in our clubs) has the
two ropes, joined by one ring. First rope has 20meters, and the each next
should be longer for about 30-40meters than first one. Before the takeoff
gliders are placed behind the towplane wtith the ropes spanned, and each
about 1-2 meters outwards from the towplane axis ("short" one left, "long"
one - right). In that configuration the whole three planes takes off and
after leaving the ground the glider with the short rope goes upwards, and
the further one lowers itself to the position below the propwash. If there
are more than two gliders (i.e. 3 or 4, but I haven't seen with my eyes more
that 3 gliders behind Wilga and Gawron), on the ground they're placed in way
1'st - left, 2'nd - right, 3'rd left etc., and in the air they're placed in
way "who has the shorter rope - goes higher", with 4 gliders on tow
additionally every glider takes it's "own quarter" behind the plane.
When releasing the gliders are departing from the last one (longest rope),
and the towplane pilot gives commands to release (i.e. "number 3 - release
the rope"), which are confirmed by the glider pilot (i.e. "number 3 - rope
gone"), and every glider goes to the left or right, depending of it's
position (the same side as it was placed on the ground).
There's also one thing - on the ground, the lighter gliders should be placed
in the first position as they'll get airborne earlier.
I've get my multiple tow rating in summer '99 and what I've noticed is that
Wilga had much slower acceleration and the ground roll was much longer. Also
the climb was quite much reduced with two gliders (Pirat and Junior, one
pilot about 90kgs, second about 75kgs). The glider on the preceeding
position looked as it was going to scrap my nose with it's rudder, so it was
very disappointing, especially whan thinking about it's rope break. Pilot
flying in the first glider has the comfort of not worrying about the
preceeding glider, but sometimes may have problems with towplane visibility
(i.e. in one of the thermal "bumps'), and the second one had to worry about
what the first one is doing and to not to hit it with own rope and feels
quite disappointed just after the take off as he's going very low for a long
period of time, but has also the comfort of very good vision of all what's
going on with the precedessors.
The only advantage for me is the money saving, as whole thing may sometimes
be very stressing. It also doesn't allow towpilot to circle with glider in
thermal to put You instantly to it's center.
Best regards,
--
Janusz Kesik
Aero Club of Czestochowa, Poland
jant...@interia.pl
www.soaring.enter.net.pl
Christopher Nicholas <ch...@cnich15000.freeserve.co.uk> wrote in message
news:96sb2j$2lk$1...@newsg4.svr.pol.co.uk...
g oneill
to what is described elsewhere.
The ring set used here is different in that one rope uses the
standard set but the other has "three rings"(2 normal 1 oversized) on it
with them the
reversed round so that the rope is spliced onto the smallest ring
when hooking up the standard set is led through the large ring on
the three set so that the smaller ring can hook normally to the tug
and the large ring, standard set, cannot go through the internal
diameter of the oversized big ring of the three set.
This was designed by "I think" Doug Walker, engineer of the
Auckland Gliding many years ago,this set up means that both ropes
separate if an emergency tug release happens
"Thomas Gemmel" <t.ge...@ndh.net> wrote in message
news:96tdgo$438$1...@passat.ndh.net...
Eva & Jürgen Breitenfelder
to dangerous.
I've seen a good friend almost dying in such an attempt, without having a chance
to avoid it!
Jo
--
e-Mail: jo...@sperberweg.de