Is pump important for a 4-stroke

[hou_zhenyu]

I plan to buy a OS FSa-110 for a new 90 class F3A ARF. There's pumped version of the engine, which is about 8% more expensive (and a little bit heavier). Is a pump really important for practicing F3A? Does the pump need more maintenance work?

Thanks in advance!

Zhenyu

[Allan Warner]

The pump on its own is not important(no change power wise, but gives a more consistant state of tune), its what it allows you to do with the fuel tank position. With a pump you can position the fuel tank on the CG of the plane and thus not suffer any trim change during the flight as the fuel is consumed. A consistant trim allows you to concentrate on practicing your aerobatic schedual without compensating for CG trim changes. HTH.

[hou_zhenyu]

Thanks a lot for the information! Considering get one with pump.

[hou_zhenyu]

One more question related to this. Quote from masportaviator - http://masportaviator.com/2010/03/31/ha ... -xt-arf-2/

"If you are using a 4-stroke engine, you can’t eliminate the upright engine as bigger 4-strokes do not like idling when inverted unless the glow plug is electrically lit in flight."

Is this true? Is OS FSa-110 big enough that suffer from this? If yes, does a pump help here?

[Flyinbrian]

Hi

Providing the engine is set up properly it should run fine inverted, I can't speak directly for the OS110a but have used YS fourstokes inverted without problems.