What Size Engine ?

Sep 26, 2004 6 Replies

O.K. Gang here's the deal: Just finishing a Concepts Models 1/4 scale Fleet Biplane. I built this 20 years ago and put a Qudra 35 (which I believe is 1 HP) which powered it quite well. I want to use a 4 stroke: Questions what size ?? this will come out to be about 18 to 20 lbs (and no I cant afford the Radial) will a 1.20 do ?? I do NOT want a overpowered airplane: I want realstic; So what have you guys been using for this weight ?>?


Denis Winters <


An OS 120 will have more real power than the old Q35. Use an 18*6 or

16*6, or an 18*4 if you can find one. You are probably going to need nose weight anyway so stick with the OS over Saito. From what I've seen, you might come out a couple pounds lighter than you think, if you can keep the tail light.

I've often advocated that when you think of engines larger than 1.2, think gas. A 2-stroke gas engine is perfect for this plane, why switch to a glow engine? They're more expensive to run. IMO, they're less reliable and harder to tune. The large gas engine also adds nose weight which you probably need on that plane.

Just curious... Dr.1 Driver "There's a Hun in the sun!"

Ahhh good point to you both: I never considered the less weight of the 4 stroke: Huummmm: and st to Dr1 Driver: I have switched to all 4 stroke and just wanted to keep in that vein. Your point will be considered "Why Switch"

Thanks

Denis <

Actually, that's a good reason. The 4 stroke might also give a "more realistic" sound than an "expansion chamber" muffled 2 stroke gasser. Dr.1 Driver "There's a Hun in the sun!"

You might consider the four stroke weed trimmer conversions offered by such outfits as Carrprecicion. They'll have the weight of the Quadra, but the 4-stroke sound. Four stroke trimmer engines are now produced by Honda, Ryobi, Shindaiwa, Stihl, and a very low-tech one is made by Briggs&Stratton. The Shindaiwa and Stihl engines run mixed fuel, just like a normal model engine, so should be ideal for model use. These engines range from 25 to about 35 cc.

Geoff, Every 4 stroke gasoline conversion I have heard of turned out to be heavy, low power beast.

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