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[ULF-1] Motorization of a ULF1.

From

Member 64

Date

2011-05-16 18:48 UTC+02:00

Message

#0270

To Mr Member 67,

I am not sure you received the text of the mail I sent to you a few days ago, after you requested answers from people having motorized a

In the years 1990, I built a ULF1. Quite a job. It flew beautifully since the first flight and I never had to re-adjust anything on it.
Then, I decided to motorize it with a JPX 2 stroke, 2 cylinder engine with 18 CV, plenty of power according to my calculations. I built a pylon and fixed it on the re-inforced airframe  with 3 attachment pints.
The engine was fitted with a wooden propulsive propeller. The tests on the ground were just perfect except for some oil spewing on the vertical fin fabric difficult to remove.
On a clear morning of september 2000, I went to my usual airfield: Fayence, Var, in the south of France, near Cannes.
Applying carefully engine power, the ULF1 went on its skid, tail high, and refused to slip on what was left of grass... see photo n°1
My idea was to go home and fit a nose wheel to solve the problem.
My friend thought otherwise: he would maintain the tail on the ground while the glider would gather enough speed for me to have control on the elevator.
I didn't think that he wouldn't be able to run in this attitude with his knees already in poor shape up to around 15 km/h. My mistake. Photo n°2.
The ULF1 started to roll on its wheel and I applied full power. Indeed, my friend couldn't run fast enough and let it go very soon after a few meters. The glider went abruptly back on its skid and stopped. Except for the engine with broke its rear fitting and went around on my head, the prop neatly cutting the left rudder pedal, my shoe and slicing my big toe. Usually, props cut fingers, hands, arms, heads but it was probably a premiere in this case...Thanks to my design, the damage was limited to a toe. Should I had designed a pulling prop, the JPX engine could accept both, I wouldn't be writting the story today...

So, with a 38 bhp engine you are going to find yourself on a much overpowered ULF1 and, if you manage to keep the engine on the airframe at take off, you'll reach Vne very quickly...

I realize that the ULF1 had not been designed to be motorized and bought an Alisport Silent "Op" with a pylon-mounted engine and foldable which gives me lot of fun and beautiful flights in the southern Alps.