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Engine basics => Engine set up tips => Topic started by: Leester on June 18, 2006, 07:36:28 AM
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One of the many ongoing projects I have is converting a Tower Kaos ARF to C/L. Everything is going very well but am wondering about what engine to put in it. It has a 55" W.S. 566sq. calls for a 40-46 2 stroke or 52 4 stroke. It has alum R/C engine mounts with the alum bar on top so engines can be switched. My best quess is it will weight in at 42-45 oz LESS engine. I have several choices my thinking is it will take more than the 46. So I was debating a ST 51, or 56 2 stroke or a TT 54 4 stroke. I did change the flaps to a C/L style not the thin R/C ailerons. What say you?
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if it was me i would use it as a test bed for all the motors till i found which one worked best
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From my experience with the Kaos as an R/C model, I would say the plane is designed to fly at a higher airspeed than we usually fly CLPA; probably about 80 mph or so.
To have satisfactory CL performance, I would try to get the wing loading as close to what a sport CL model would have.
If you have ground clearance for a 10 inch prop, you will probably want the engine to turn a 6 or 7 inch pitch at least 10,000 rpm to get air speed of at least 60 mph.
Hope this little bit of info helps to narrow your engine choices.
Jim Oliver
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Well with everything almost buttoned up with a ST G 51 I am going to be right at 60oz. I don't know how you figure wing loading, can anybody help me with this? Thanks
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Well with everything almost buttoned up with a ST G 51 I am going to be right at 60oz. I don't know how you figure wing loading, can anybody help me with this? Thanks
566 square inches and 60 oz? Sure. The wing loading is the ratio of the weight to the wing area. In stunt we usually use ounces/ square foot. So:
wing area = 566 in^2 x 1 ft^2/12 in^2
= 566/144 = 3.93 square feet
wing loading = 60 oz/3.93 square feet = 15.26 ounces/square foot.
That's a pretty high wing loading. at least for a competition stunt model. There have been several NATs winners in that range but they were designed from the start for that sort of thing, unlike the Kaos. And, they had the best TP motors available, which makes all the difference in the world.
I suspect the airfoil is pretty thin compared to, say, a Trivial Pursuit or similar. Expect to have to use a lot of flap deflection, and have relatively soft maneuvers.
Brett
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Thanks Brett: I got it down from the projected R/C listing which had the weight at 5 1/2-6lbs. and wing loading at 22-24. I should have it ready to fly next week, if nothing else it was fun doing it.