What is this engine?

[Steve J.]

Can someone identify this for me?

[Shackas]

Ex-soviet, "LM".
If I recall correctly, they were sold here in Australia by Macheast Engines back in the 1990's.
I think they may have been one of the first engines made to the small venturi & muffler requirements.

[Steve J.]

Thank you Shackas. It's going on a Free Flight with no muffler and a bigger venturi.

[Shackas]

That's exactly what I did with mine.
Went on the front of a Pulteri setup with VIT and a/r.
Enjoy!

[Steve J.]

What would be a proper size prop for it?

[Shackas]

What a coincidence .... I was just logging on to suggest a couple of things and you've asked the question that I was going to going to address.

Prop size - F2D combat size. 6.6 x 3.5? Not the best for a FF application, but sounds great.

Fuel system - Probably needs to be a bladder, unless you've tapped the case for pressure. Won't work on suction.

Glo head - If it has the original glo head insert under the clamp ring, send it to someone to retrofit an insert that accepts Nelson-type plugs

 

[Steve J.]

I assume it will only be happy with straight 80/20 fuel. I hope Rossi / Conquest inserts will fit.

[Shackas]

I think it was made in the early days of the transition of F2D to 10% Nitro, so I'd go with that.

[FF Bruce]

My guess is it's a .15 so a 7x3 should do just fine

[faif2d]

Use whatever prop will get you about 25-28K on the ground.  I think 7-3 will be to much.  7-2.5 might be about right.  Probably needs to be a glass fiber to keep it in one piece.

[Konrad]

In my day we would run 15's (Rossi, Cox, Nelson) on reworked 7X5 wooden props with a ground RPM 26K to 27.5K RPM. This was for the old AMA 422 QM pylon racing (RC) on 15% nitro.