rcwinder

I re-installed a new motor and mount on my Slo Stick. (bear with me, still learning) I initially set the down thrust at 3 degrees. My coach flew it and told me I needed more DT. So cleaned up a few mistakes and re-installed motor with what turned out to be 7 degrees DT. I flew it today and it required constant up elevator to fly level (regardless of throttle). I moved battery back a bit and while it behaved better it still needed up elevator to maintain level flight. Elevator trim all the way up wasn't enough. Is my downthrust the culprit here? I read elsewhere that 5 degrees is the better number? [link=http://www.rcecho.com/Brushless-Motor/][/link]

GaryHarris

The CG recommendation is wrong for the Slo Stick in the manual and I forget what it was, Ill look in a minute. But I would go back to 3* of DT and adjust your CG to fit.

GaryHarris

Actually 2* of DT.

http://www.wattflyer.com/forums/showthread.php?t=27852

And thanks. Now I think Ill order another one.

KitBuilder

Order a new one??

GaryHarris

Another. I've had several.

Gray Beard

My Feedback: (-1)

Thrust angle with either electric or wet power has no set degrees, it is whatever is required, nothing more or less. I set up new planes with zero thrust then decide during the trim flights what is needed then go trial and error. I think 2.5 degrees of down thrust is as much as I have ever had in any plane. I did have a little scratch built Fokker D-VII that took a bunch of right thrust but still only had 2 degrees of down. Most of my stunt planes like Extras and Sukhois have zero engine thrust at all.

jester_s1

For what it's worth, you don't adjust your CG to fix trim changes. CG is all about getting the best handling characteristics for your plane and is the first adjustment to do once you're trimmed for straight and level flight. On a high lift floater like the Slow Stick, get to cruising speed and then cut the throttle. Don't touch the elevator while you watch for the next few seconds what happens. If the nose drops immediately, you're nose heavy. If the plane continues on for a few seconds before gently dropping the nose, you're good. If the plane continues on and the nose rises slightly just before a fast nose down descent you're tail heavy. Get the CG right first and trim for straight and level flight, then adjust the down thrust so that you don't get any attitude changes with changes in throttle. One caveat here is that if your thrustline is way off, you'll find that the nose instantly reacts when you cut the throttle, which will mess up your results. If you see that, adjust the thrustline to get it at least close then work on the CG.

Gray Beard

My Feedback: (-1)

Or you could just trim the plane for straight and level then land and see how much trim you have in the elevator and rudder. Up trim tells you it is nose heavy. CG is an easy thing to figure out, in flight I still use the old pattern trim chart that tells you if your plane does XYZ you should do this. AMA still has trim charts on there web site and they even tell you about thrust angles and incidence. The AMA is your friend!!

im_a_rcav8r