Telemaster 40 tow plane help?

[FlyGuy]

Good day,
I'm in the process of scratch building a Telemaster 40 with the intent of towing 2m sailplanes. For the motor I was planning on using a O.S. FS-48 Surpass four-stoke.
Any comments if this is enough power?

Thank you,

[JimD]

Between 2007 and 2011, I built four Telemaster 40's. Two with glow and two with electric. One of the glow engines was an OS .52 4-stroke and the other was an OS .81 4-stroke. The OS .52 got the job done with Easy Gliders, but the .81 was by far the best for anything bigger and/or heavier than the EZ gliders. That said, we did many, many hours of EZ Glider towing with the OS .52 powered Telemaster 40 with great success.

So, the O.S. FS-48 should be fine for Easy Glider type sailplanes, bigger and/or heavier built-up or fiberglass sailplanes probably should be avoided unless you want to get a larger engine. If you decided to get a bigger engine, stay with a 4-stroke. Our experience with 2-stroke glow for aerotowing was not so great.

As for the airframe,definitely add the flaps to the Telemaster 40... no matter what engine or motor you pick.

Front Telemaster 40 powered with a .46 size equivalent electric motor, rear powered with an O.S. FS-52.

[horsefeetky]

normally these needed a bit of weight in the nose to balance any way so a larger 4 stroke engine is easily done. also make sure to get your fuel tanks tucked back under the L.E. bulkhead so it sits well over the CG area.......i just recovered my giant roadrunner similar to giant stick with gas 40cc on it for mid size towing here at home this year.. need to re maiden it soon....

[FlyGuy]

Thank you JimD and horsefeetky for the information, very interesting about the the fuel tank. The Gentle lady will be about the largest glider that I plan on towing, I'd like to build the 2X4 glider, it looks easy to build but not exactly scale gliders like are on this forum.

I have the Senior Telemaster with a 25cc Roto gas engine that I thought I was going to use as a tow plane but changed my mind.

[JimD]

Take a look at this thread for some ideas about using the Gentle Lady: https://forum.scalesoaring.com/forum...ner-sailplanes

[FlyGuy]

Thank you for the link Jim, Interesting to see those modifications done to the Gentle Lady, that is definitely food for thought. BTW, I wanted to mention what a nice fleet of Telemasters you have. I have the plans drawn up that you show on your Post #11 on the above linked page. My club would be very excited to see aereotowing at the field this season.

[JimD]

You might want to check this thread also: https://forum.scalesoaring.com/forum...uper-tow-plane

[ARUP]

FlyGuy- you can tow polyhedral RES sailplanes but it gets a little 'squirrelly' and chances of ground loops are a lot higher. Can you say 'Dutch Roll'? The 'flattened' wing with ailerons on your Gentle Lady will diminish that worry! You might even try a 'gull' wing!

The Sig Riser really comes up off the runway fast with no tendency to catch a wingtip. I was expecting it to be a bit of a problem and had an 'extra itchy trigger finger' on the release in case of mishap. That's why I kept the rubber band wing retention because less damage would occur vs bolt-on wing. So far so good! If I built any more conversions like this then a bolt-on wing would be better. The rubber bands degenerate pretty fast sitting in the sun all day.