atron

Hi folks;

I just had my fist attempt to sailplane tow last weekend (oct, 15) and had two succesfull tows.

Tow plane is 60 size Ugly Stick with flaps and ailerons for power one OS 90 two stroke on the nose and 14-8 prop. Sailplane was a very old ASW 17 and 120 inch wingspan, do not know the origins or name, but had a flat bottom wing, both were fitted with tow release mechanisms.

On the third tow, had the impression of being towed too fast and the sailplane started to roll uncontrollable until one wing gave up. Lost the fuselage and have to repair one wing.

The experience was formidable

Any ideas on what happened?

Alexis
Mexico City

BarracudaHockey

My Feedback: (11)

Use a bigger lower pitch prop, you were probably going too fast.

soarrich

My Feedback: (98)

BarracudaHockey
I like my AMA better, 77727, I always wondered who got 77777.

atron

I agree, if it was a older sailplane most of them where not designed to go very fast, sound like wing failure or one wing jumped off it's alinement pin.

da Rock

The glider could have been upset by the downwash from the tow plane. When being towed, the glider should stay above the path tracked by the towplane. The turbulence of the towplane dissipates straight back, out, and downward. The glider should ride above that.

The trailing turbulence of the towplane will be generated based on the size, weight, and speed of the towplane, and the drag of the glider it's towing. A large glider will cause the towplane to generate more turbulence than a light, small glider will cause.

The glider could also have simply stalled. If it had stalled by itself, nothing would have happened out of the ordinary. But since it was being dragged and not allowed to "pause" who knows what it'd do. And it did.....

da Rock

Some years back a bunch of glider buddies and I experimented with towing. We started off doing the towline deal. It was a major pain. Somebody had to learn to fly the towplane. And everyone had to learn to fly under tow. Neither was simple. And it was a pain to bring out a towplane and all it's equipment.

The biggest pain was working out the equipment for each and every glider that was going to be towed. Everybody had a couple of different gliders they wanted to use depending on the kind of day (lift/wind/etc) and modifying was extra work.

We wound up rigging a very simple cradle on the towplane. You could stap anything to it and it'd take it aloft and let it go. Any glider could be piggybacked as is. Nobody had to retrofit anything. Nobody had to buy anything extra or hack up perfectly good airplanes. And most of all, it took almost no skill to have your glider piggybacked.

And the glider being piggybacked had little or no risk of blowing the tow. And if the release mechanisms didn't work, the towplane simply came home with the glider still attached. If you want a thrill, be flying the glider that won't release. Or be flying the towplane.

The towplane has to slow down to land. And landings are when tipstalls can cause the most damage. And the sucker has this thing on a string jerking and pulling. And the sucker has to slow to landing speed. And it makes it to the ground in one piece, touches down AND STARTS TO SLOW TO A STOP. And what does the glider do? It's had to stay above the downwash, and is now how high? And tied to an airplane that's stopping directly in front and under it....... And that airplane has a propeller that's still turning.

Piggyback has a lot more going for it.

Campgems

I had my Sagita 900 to the field for the first time today. It turned out to be to windy for us, but a couple of the guys were talking about making a launch plane like you described. Apperantly they had been talking about it for some time and hadn't gotten around to it yet.

Darock, do you have a photo of your setup? I've got a big old highwing that may be ideal for that project. I got it as a bunch of stuff I got from a guy retiring from the hobby. The Sagita was part of the purchase. Along with a Bird of Time that is ready for radio and cover and another smaller glider. It would be great to see how you set things up. You mentioned that there was nothing required on the glider, so you must have had some clamping mechinismun (sp?) to lock the glider to the tug. The release mechanics are what I'm woundering about.

Thanks

Don

atron

Thanks for your prompt response....

I am being told by the people who watched that the wings looked like "V" moments before the breakdown. I (sailplane pilot) do not released when the wing broke....as you know, there is nothing to do to a flying fuselage (besides releasing).

Now i am looking for a "unexpensive" fuselage, even if it is not scale as i am decided to keep trying, but unhappy to expend too much.
Any source to get one?

mtt3107

Sounds to me like this was one of the Astroflight ASW-17's without ailerons.
If that is the case, there's your problem.
2 channel ( rudder/elevator ) gliders are notoriously hard to tow, especially when it's a polyhedral ship a la Salaire.
On a 2 channel glider, you rely on the rudder and the dihedral to keep the wings level.
On tow, the effectiveness of this is greatly reduced, since the tow plane will always pull the sailplane straight.
On a sailplane with ailerons, it is very easy to keep the wings level with the ailerons, and the whole thing becomes much less stressful..

The only way to tow a 2 channel sailplane is to keep the airspeed as low as possible, as already indicated.

atron

mtt3107


Yes i probbably ar rigth it was an Astroflight ASW-17, but i did made ailerons (strip about 12 x 1 inch).

I am still trying to remember the fligth and all i can remember is myself trying to level the wings at high speed.

Alexis

simhatus

Hi

Have done quite a lot of towing both with the tug and the glider. i would say a 90 powered plane is a bit on the small side and as mentioned earlier to fast. Towing a 2 channel should work ok although ailerons is easier.

I have towed with 38cc and 61cc powered planes which provide plenty of power at a slow speed, in fact one of the problems was the glider tending to fly faster than the tug.

The important point is not to try and recover it when it goes wrong, just release land and try again. is does take quite a lot of practice to get right.

Simon

Sneasle

Is there anyone hear who can share their tow setups? I am lookign to build the spirit eleite and bird of time, but for several reason i don't want to work with hi-start launches with these and would much prefer a tow plane if possible over putting brushless int he nose.

fjarratt

We add a lightweight break-away line at the glider end of the tow line when we tow smaller wooden sailplanes. Sort of like a circuit breaker. A single strand of 30 pound kite line seems to work well. Acts a third hand on the tow release. If the sailplane pilot gets sideways the line will break before the wings fold. If the tow goes wrong, things can happen too fast for a pilot to react who is new to aerotow.

Towing the older wooden planes is fun. Gives them a second life. We in the USA have focused too much on just SCALE aerotow. Personally I feel that the smaller scale sailplanes (less than 5 meters) do not fly as well as the old Standard class thermal sailplanes - especially for pilots new to sailplanes and aerotow. I enjoy flying all sailplanes, not just the latest glass birds.