hdeubler

Hello
I recently purchased a short kit for a 78", 1/5 scale ME BF109 where I have 2 questions.
1. the plane is supposed to weigh 12-16lbs and the recommended engine is a OS FS 90 2 stroke. Does this engine sound strong enough for a kit with this weight.
2. The recommended prop size is 15x6 and the scale spinner diameter is 6". How will a spinner of that size effect the engine performance? Do you think that the propeller can still produce enough thrust to power the plane?

thank you
Heinz

mgnostic

The spinner size really isn't much of an issue as most of the thrust comes from the outer portion of the blade. Go with a spinner that fits the airplane. As for the engine, if it is an older design it may have originally been built with a .90 two stroke. It may be that the .90 is relatively easy to hide under the cowl. The problem with a .90 two stroke is that you are reaching the line where two stroke glow motors start to become gas guzzlers. Unless you already have the engine sitting on the bench you are reaching the point with a 1/5 scale plane where a gasoline motor might be a better choice. I would suggest doing a search for others who have built to your specific plan set and see what they used for power.

hdeubler

Matt
Thank you very much for your reply. This was very helpful, especially the advice about the spinner. I actually already have a Saito 125a 4-stroke and yes, I am aware that I might have to take out a 2nd mortgage to afford the fuel. 4-storke engines just sound so nice :-)

mgnostic

I may have misread your post. I thought you were considering a two stroke. Four strokes are a little more economical in regard to fuel. Best of luck with your project.

SanBug

My Feedback: (15)

Post some build pictures please, Would love to see this project...

US185Damiani

This sounds like the Platt 109. A .91 2 stroke is fine but a 1.25 Saito would be much better.

carlgrover

The OS 108 is the engine of choice for that plane.

carl

US185Damiani

An inverted 2 stroke severely damaged my Platt 109. They’re notoriously unreliable.
a DLE 20 or a 1.20 4stroke would be a much more reliable choice.