Hello,
The initial issue was hunting and then rolling and take off of my electric planes. Please visit
https://stunthanger.com/smf/open-forum/plane-trimming-no-side-issues-please-this-time/ to see what was discussed, otherwise this what I wrote below will be out of context.
Today, I have tested eParrot (please see the attached) in six flights. The main objective was to check if the plane rolls better and longer if the release is at the moment when the propeller starts rotating. All flights took off from the hard surface.
Previously, I waited with release (I am using the stooge) until the motor reached governed RPM.
I am using Keith Renecle's governor in which first four seconds of the motor run are ungoverned.
The results were as follows:
1. Reasonably good rolling for about four seconds and then sudden acceleration with the governed RPM and take off.
2. There was no plane jumping and up and down tail wagging like in the case when the plane was held in the stooge for four seconds and
then released.
Ad.1 and 2: the foam tires were made more slippery by wrapping the electrical nylon tape around them. This resulted in less frictional resistance in the Y airplane direction and, consequently, in less bending and twisting of the landing gear wires when eParrot started rolling. The landing gear wires and the tires represent the dynamic system that has a tendency to oscillate when the friction force between the tires and the hard surface exceeds certain value.
This value is now lower and this improved the rolling behavior (ref:
http://www.maths-in-industry.org/miis/108/1/Airbus-ShimmyReport.pdf.)
I will replace the current wire in the eParrot's landing gear (0.118") by the wire having larger diameter. Perhaps 0.125" will be enough to further limit or even to eliminate the problem.
Grass take off release must be done after four seconds from the motor start for the electrical system to be in the governed mode in case of the prop. strike. This means that the grass take off will be fast and short (I have not tried it yet).
Other issues: the leadouts exits were moved 3/4" FWD following Ted Fancher's suggestion. It seems that this change, associated with the more slippery tires, improved rolling on the hard surface.
The eParrot's nose has been extended and the motor and battery moved FWD ~1.7-1.75". This gave much better grooving and the tendency to hunt disappeared. Whatever "waviness" is seen in the eParrot's level flight now can, in my opinion, be contributed to minute errors in my input, shear wind and/or air turbulence.
I would be grateful for comments, opinions and suggestions.
Thank you,
Matt
Topic: Electric Plane Trimming-do and don't (Read 1588 times)
