I've been trying to decide what engine to put in my Four Star. I keep eyeballing that OS .60FP sitting on my shelf. Would I be buying trouble? What issues might I run into? My thought is to fly it at less than full throttle but have the ability for some good vertical flight. What say ye? Thanks in advance.

When I had mine I had an OS46AX and it was more than enough. With a 60 you would probably not even have the ground clearance for the prop you would need and even if you did, you would probably have a hard time getting it to balance, takeoff would be a just a click or two above idle and flying at about 1/8th throttle and much more than that may cause the plane to flutter itself to pieces and this all depends if you can even shoehorn the thing into the mount.

Veritcal would be good enough for orbital work and would rival the lanuch speed of the space shuttle in scale. You would definitely need to strengthen the firewall by pinning it and throttle management would be an absolute must., Heck that's the recommended engine for the 60 size and it's plenty on that plane.

Now I am saying I do not recommend it but I got to tell you it would be wild to see

Bill, thanks for the rapid reply. Well, I'm not much into wild......yet.......so perhaps I'll put something else on.....I have a Towers gift cert thats burning a hole in my pocket so perhaps I'll spring for an OS 50 SX. I think this might be a superb engine for this plane. I had another Four Star months ago.......RIP.......and it also had a .46 AX in it. You're right, it did great. I have one .50 SX that I've used in other 40 sized planes and it really is a nice setup

A 60FP is not that powerful of an engine, swings like a 12x6 or a 12x8. the 46AX swings like a 11x6 or 11x7 -prettycomparable. Plus, the FP engines dont have BB, so they are light for thier size. If you already own both, why not?

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Whatcha wanna bet that the OS.50SX can kick that .60FP's butt in every power production use except maybe swinging a 14x6 the fastest? I'm not even sure it would lose in that case, to be honest with you.

Like you said, throttle management would definitely be required. The 4*40 is not a robust airframe in the first place, but it is adequate for its intended purpose. I don't think that hovering at half throttle was in Bruce's list of intended purposes, though.

I scratch built a model some years ago (dubbed The Hail Razor - you had to be there) that was in the forty sized class of airframe. However, I built it with some provisions so that I could fly it with an ST Bluehead G60. As one modeler told me, "Ed, that model doesn't takeoff, it explodes off the ground". It was a lot of fun to fly, but I had to be constantly vigilant on keeping the throttle at 1/2 or below. No, that model would not come apart at full throttle, but it would turn into a speck about as fast as you blink your eyes.

Experimentation is one of the reasons that I chose to stay with model aviation instead of full scale aviation. Give the .60FP a shot. Build a battery box behind the wing so you can bring it into balance and have a ball.

Guys, I stand corrected. I skipped right over the"FP" part of it.

You may be correct. It may be just about right in line with the 50SX. There is no harm in trying. He's already had one so he knows what the plane can do.

That's like the guy at our club last year screwed a Saito 120 into a H9 Twist. No that "WAS" definitely overpowered. On the second flight, it loosened the firewall even after pinning it 2 times per side. After he first started it he had the idle a little higher than normal and he turned his back just long enough to allow the plane to start taxiing out to the runway on it's own. He found out on the maiden that landing it was not gonna happen as long as the engine was running.

If you feel strongly about wanting more power and performance, you're probably ready to move up to a higher performance airframe. There are plenty of Extras, Edges, Caps, etc. out there that would be great fliers on that .46FX. Go for it.

Why would you want to ruin a good airplane by over powering it so.A 4Star 40 flies just great with a good 2 stroke 40/46 on it,it will do any thing you want it to do and you won't be stressing the airframe .I have flown them for years with various 2stroke 40's and 46's and all have been great fliers that did just what they were supposed to do.That is my .02 worth