View Full Version : Glider towing with motorglider/ULV

25th Sep 2005, 21:01
My glider club wants to get rid of our glider towplane (Bellanca Scout, 180HP taildragger), due high fuel costs.

The idea is to buy a motorglider or very/ultra light tow plane.

Can anyone give me his/her experience about towing gliders with these aircraft types?

In my personal opinion (as a tow pilot) this light weight aircraft are not suitable for the job...

Thank you for your input.

25th Sep 2005, 22:55
What motorglider or ULV is certifiable to tow a glider? Which of them has the performance and structure to do it comfortably and safely?

26th Sep 2005, 06:12
Motorglider tow will need more takeoff run, once airborne climb rates are not that much smaller, towing times are similar due to faster descend (air brakes). Optimum tow speed is lower for motorgliders, very nice for wooden gliders, bad for standard class full with water.

On short airfield or airfield with soft surface / high grass motorglider tow is not recommended, on long, hard and dry airfields it is very nice. Iīve been towed by the first Rotax-converted Samburo (80 hp) which was used for certification of motor-glider-tow, fine with single seaters, a nightmare with the ASK21 !. Same for the 80 hp Dimona. 100hp and 115 hp turbo Dimona work fine. 100 hp Rotax Falke is surprisingly good, mainly due to the low weight, a tow with the Duo Discus works fine.
Grob 109b converted to the new 140 hp Limbach Turbo (liquid cooled, with intercooler) tows very well, but the engine is still a little troublesome. If you want to buy one, send me a message, there is one for sale at the moment.

Some ULV make good towplanes, too. Durability is much worse and handling quality sometimes not what a serious pilot would expect. Accident rate is quite high. Lost two friends in ULV tow planes in the last two years, both spin accidents :(
I donīt think they are really cheaper, as the ammount of maintenance is high and the lifetime of the airframe is low.

In our club we run a Diamond Dimona TC 100, works fine for single seaters and is acceptable for double seaters, but not under all weather conditions. Our airfield is low altitude, dry grass (sandy soil) and 800 m long, surrounded by high trees.
We started with the 80 hp engine in the same airframe, which was not enough for composite twin seaters. Ka2b worked well, but was not legal anyway (to heavy). The Rotax 912 A3 made it to the TBO limit without trouble, so no towing related engine problems. Fuel consumption was 16-18 l unleaded premium.
Changed to the Rotax 912 S two years ago, now twin seaters are legal, but not every type is recommended on our airfield. ASK-21 works fine with a little headwind and is marginal in crosswind. 600 m tow typically done in 6-7 min for single seaters with 20 liters of unleaded premium / hour (so about 2 liters per tow). Had an engine replaced after 400 hr due to high amount of metal chips in the oil system and torque values (friction) out of tolerance. Rotax replaced our engine for 1/3 of the cost (400 hours flown, 1200 TBO). Heard from many clubs that they had engine trouble well before TBO with their Rotax 912 S, but cannot confirm any numbers. (by the way, the Lycoming in our Husky also never reached the TBO)

Best thing is to visit a club or a flying school which operates a motorglider tow plane and simply try.
Fuel costs are reduced dramatically for sure, but overall costs are not that much lower compared to conventional aircraft, especially if you compare your old tow plane to a new motorglider. New airplane are really expensive today, so airframe costs per hour are much higher compared to a previous owned aircraft. There are not many used motorgliders available on the market. For ULV this is even worst, a new ULV (suitable for towing) is well above 60 K$, you can be lucky if you make 3000 hrs out of the airframe before replacement of several major parts is necessary.

26th Sep 2005, 19:02
Dear Volume,

Thank you very much for your reply!
As chief tow pilot I am involved in the flight safety issues. The financial part is done by the committee. My input is asked for the flight technical part.
What I read/heard is common engine failures in motor-gliders which are used primarily for glider towing.
We are towing from an old runway(long hard surface, which is OK I think for all operations) and grass (<15 cm, which is not really as flat as a golf course...)

I am not in favour of changing our present plane into a motor-glider/ULV. However I have to make a report with as many reasons as I can find to build my case.

So if there are more people who can give their opinion, I am looking forward to your reply...

Flap 5
27th Sep 2005, 15:04
How about the ASK21 Mi - self launcher:


(Not for towing of course but it removes the need for a tug)

27th Sep 2005, 15:23
Volume's comments are quite correct.

My club has owned a 115 hp Dimona for 3 years (the other towplane is a 180 HP MS893 Rallye Comodore).
It worked quite fine except for two-seaters on hot days (1000m/3000ft grass runway, 150m/450ft AMSL - northern France can easily go up to ISA+20 !). However, the engine reliability issues prevented it from reaching the forecast economical breakeven (not enough flying hours). The engine startup procedures are a bit more complicated on the Rotax than on the good (?) old Lycoming, so more training is required for the non-professional pilots. Moreover, a road has been built at the upwind end of the runway, reducing the safety margins.
As a result, the Comodore is still here and the Dimona has been replaced by a Robin DR400.

Other clubs in France still operate Dimonas, though.

Maybe you would get more answers on a gliding oriented forum such as news://rec.aviation.soaring

Piltdown Man
28th Sep 2005, 09:49
From the victim's end, my favourite tug was a 200HP Robin with three blade CS Prop. Brilliant untill it caught fire (MOGAS). Then, being on the delivery end, a Robin 180 with four bladed prop (not bad!) but best of all, a 180 Cub (until the wind got up - then the Robin's came into their own). The thing in common with each of them was:

1. Strong airframes.
2. Good on rough ground.
3. Reasonable aerodynamic controls (to give some control over wayward gliders).
4. Powerful engines.
5. Reasonable excess power.

If you cut back on any of the above (excluding specialist stuff like towing vintage stuff), you will be cutting into your safety margins. It costs X to launch a glider by aerotow. Charge X plus a bit, don't try to do it for less.

And, if you see a turbine powered tug, get it! Yes it will gobble fuel, but Jet A1 is cheap(er). But due to the nature of turbines, you'll launch the entire grid before you know it.

28th Sep 2005, 10:10
Don't skimp on the tug aircraft. You want a decent amount of excess power in reserve, especially when towing a heavily ballasted glider.

If I thought that the committee would put cost-savings over pilot safety, I'd resign and go somewhere else.

28th Sep 2005, 14:28
They were using CT SW ultralights as tugs at the International VGC rally in Germany this year.

Nastiest tow I've ever had (in a heavy, draggy single seater, the Slingsby Petrel)

We only gained significant height when we flew through thermals, and occasionally lost height in the sink!

A French guy had a similar experience in a heavy 2 seater behind the CT. Fortunately they also a Wilga which they mostly used for the 2 seaters.

28th Sep 2005, 18:11
I've done some tugging in a Rotax engined Falke. You probably wouldn't want to tow anything larger than a fully ballasted 18m glider with it (can't remember what the limits on it are) but in terms of turn round times its efficient enough.

I currently Robin 300/400 (depending on which one is availabe) and would agree with the other points of view - you can't beat a bit of grunt at the front.


Piltdown Man
29th Sep 2005, 08:42
Sounds like you tow at LGC - like what I used to. Regards to all from the guy who jumped from the Caproni.