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Engine basics => Engine set up tips => Topic started by: Curare on July 03, 2014, 05:20:58 AM
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Hey guys, I've just been messing around in the workshop getting a number of props ready for the weekend (if I get the parts I need), and I have a selection of wood Vess style props, and APC's.
In my RC experience, some motors were happier swinging a prop with a lighter mass, (usually the bigger engines, above 20cc), and some preferred the heavier flywheel weight of an APC. Despite what the internet nerds have told me I never noticed much change in response, as that was always dictated by servo speed. Same engine, same servo, different prop= no change in throttle response.
Thats all well and good for RC, but in control line, I'm guessing things are going to show themselves a lot more, would I expect a change in cycling? I.e. light prop, it comes on late?
I fly off a dry lake bed for the most part, but the other field here is grass, I get the feeling that the APC will survive a bit better?
Cheers
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Greg,
In control line stiffness kinda counts more than weight. The difference between APC's and wood is about double in weight. The Carbon Fiber props are about half way between them. Depending on the rpm you fly at the heavier prop can pitch the nose more than the wood ones. For the most part you can trim for whatever prop you want. The main thing is to first find an rpm that the motor is happy at. Then match the prop to that rpm and that pulls the plane. I have recently done tests with a narrow blade wood prop, undercambered wood prop, Master Air Screw and an APC. All were 11x5's in the end the engine and plane work the best on the APC. Test and see what works for you setup, it is pretty obvious when the prop is not working.
Best, DennisT
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Cool, thanks for that Dennis, sometimes I tend to dissapear up my own behind trying to determine things pesudo-scientifically ...
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I have found that a 12-6 APC pulls better than any other prop on my Anderson Spitfires. I also notice way less vibration with them over wood and I think it is because it dampens out the pulses. On my 850 square inch Taurus I can also run a wood 13-6 OK, and there is enough weight to the prop to eliminate the vibes.