[recon]

I was out flying my twist this morning having a blast until the third flight when I pulled to the vertical to hover about 30ft up when the engine quit. Not much damage, I landed it on the wheels but the gear bent and dented the bottom of the wing. Anyway, after walking out to get the plane, carrying it back, inspecting the damage, and talking to my friend about repairing it I felt the engine and it was still too hot to touch. Am I over heating it doing these hovers? It is a GMS .47 and I recall reading something about them over heating and how to fix it. Thanks.

[Gary Maker]

I am not sure of the type of setup on your plane but it is usually a couple of things that could cause your engine to heat up.

Running an engine too lean is one of the worst offenders. Peek it and then back off the high speed about 2 or 300 RPM.

If the engine is cowled, make sure you have enough opening for the air to escape. I was told the best ratio is for every inch of opening to let the air in, you should have 3" of opening to let it out. Also blocking off the side of the cowel opening opposite to the engine cylinder assures a much better airflow over the cylinder.

One other thing may be using too much prop which loads the engine down too much. On a .47 engine I would think an 11 X 7 would be about the max size. For better vertical you could use an 11 X 6 or even 5.

Just a couple of thoughts. Hope this helps.

[JimMoss]

Neat idea ....... closing off one side of a cowl to get more cooling over the head of the engine!!

[Chris Cann]

an 11x4 would be nice for 3d flight on a gms 47 if i'm not mistaken brady has a fun fly prop on it 12.25x3.75 i think...maybe 12.75x3.25

[Gary Maker]

Yes, I owe that great idea to my buddy Jim Moss who helped me come up with a way to keep my engine from cooking.

Jim, it has never ever gotten anywhere close to getting that hot again since I permanently made that fix......Thanks again my friend!

[recon]

Yes, I have a 12.25x3.75 on it. It is on my twist 3d, so there is no cowl. I thought I remember reading about adding or removing shims or something that would help with over heating?

[JimMoss]

No prob Gary!


By adding shims under the head you can reduce compression there by reducing temp.

[wise guy]

Hi Recon I have a GMS .47 in a fun fly plane and the best prop that I use is a 12.25 x 3.75 or a 12x 4 These props allow good low speed and good vertical performance . I was burning allot of glow plugs up and having problems with heat then i put in the 2 head shims in the engine and have not any problems since. Engine runs great now . Try the larger props mentioned earlier I think you will like the performance of your plane.