Flexing Motor Mounts

My Lanier Stinger 60 ARF came with motor mounts that are not rigid , they flex slightly especially at low rpm. Once the throttle is advanced they smooth out quite well.

I have never had a problem with them but the guys at the field think they are dangerous and could fail. Also they say that there vibration effects the motors operation - it is a Saito 80.

I have about 3 hours flight time on them and they look and perform fine. Plane flies extremely well , except requiring over three oz added to the tail to get it to balance. I think a 2 stroke engine 60 to 90 would be heavier and thus require less tail weight.

Is there an issue with these flexing motor mounts? Any suggestion , thoughts , ideas etc.

Thank you in advance.


Reply to
Allan Schneider
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Allan, About the tail weight....it is better to have a few ounces of weight added to the tail than to have many ounces of weight added to the nose when you consider that the fuse is a lever with the fulcrum(CG) towards the nose. You would be adding may more ounces overall to the airframe if you tried to balance it with a heavier engine.

Phil AMA609

Reply to

Regarding the tail weight, a heavier engine would require additional tail weight.

Reply to
Brian Morris

There is nothing wrong with using a flex motor mount. The idea, of course, is to reduce vibration transmitted to the airframe and electronics. I have the same plane but fitted with a YS110 engine and a Gator soft engine mount. If you want to reduce tail weight, you'd need a lighter engine and not a heavier one.

Reply to


I use OS engines and the motor mounts that OS makes for their engines. These are light weight aluminum and extremely rigid. Maybe Saito makes mounts also? Anyway they work extremely well, and I have never had any problems.

The glass-filled, plastic, soft or flexible mounts all vibrate to some degree. Horizon uses a cheap piece of pot metal crap that has been know to break at the engine mounting holes. One has to be very careful when selecting an after market unit, because there is so much junk.

There is a myth that mounts shouldn't be rigid and they should be flexible to some degree like those in cars. I don't agree with this, and neither does OS. I don't detect any vibrations in my airframe when I crank up the engine, but I have observed the el cheapo mounts in operation with the planes shaking like cement mixers.

Anyway, I suppose one has to do a little experimenting. BTW, the OS mounts aren't cheap which is probably why one doesn't see them too often.


Mr Akimoto

Reply to
Mr Akimoto

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