The last few times out flying, I've been working on the trim for this plane. Last Thursday I was out and after several trim flights, I decided I didn't like the direction I was headed so I quit and went home. The plane was flying pronounced tail low, there was a fair amount of "up" elevator all to get that "equal turn on both insides and outsides. Also when the motor quit, the model had a tendency to float a bit. Not surprising with the up elevator. After thinking about the plane I decided to go back to point "zero" and start over. I centered the elevator to stab with the flaps at neutral and reset my handle back to equal amount for a truly neutral setting on the lines. And then I added some upthrust. I added 2 washers to the "top" mounting screw and 1 each washer to the right and left midway mounting screws.
I then went out this morning and did 5 test flights. The model was very close on the first flight. I adjusted the elevator push rod just a little and now I was getting a very near equal turn on both inside and outsides. The tail was flying very close to being straight both upright and inverted. A minor handle adjustment for neutral and it was flying very well. When the motor quits, the model settles into a nice decent and doesn't float like before.
A recap of the big problem I was having was that the model would turn a lot tighter on the outsides than the insides. When I adjusted the elevator push rod to get equal turns, the elevator was pointing up some and the model flew in a tail down attitude. Since I reset the controls and handle and added some upthrust, the model is flying very well and in the correct attitude.
I included a picture of the spinner to nose ring to show the amount of upthrust that 2 washers created. I could have used only 1 washer, but I wanted to be sure that the upthrust was plenty to really see what effect it had on the model. Here's the kicker - I used my CAD program to draw in what 2 washers do to the thrust line and it measured out to be........ 3 1/2 degrees of upthrust!
One thing I learned when flying RC helicopters, was give the helicopter what it needs, not what the "normal" is. In other words, if the normal high pitch would be 10 degrees to maintain RPM, and your helicopter still revs up, then give it 10 1/2 degrees to get the RPM to stay the same.
I'm leaving it like it is for the next several flying sessions and I'll work on getting into a finer trim now that the model is flying a lot "happier".
Topic: 2016 Electric Stunter Build Log (Read 64621 times)
