Mixing Transmitter Controls

[Erfolg]

I fly electric gliders, 2 off “Sagittas” (2m or 600) and 1 “Toll Heidi” (48 inch).

They all have their motors aligned with the tailplane, essentially along the axis of the fuselage. In the case of the two Sagittas this is probably in the region of + 3 degrees to the underside of the wing, or +5 degrees from leading edge to trailing edge (Eppler 205), the Heidi is approx +2 degrees to under side of wing ( MH 32).

All suffer from severe pitch up on powering up at launch and whilst flying . The Sagittas have a max power of approx +160 watts (3 lbs) and the Heidi of 130 watts (weight 1.5 lbs).

I normally attempt to control this by use of down elevator, in the case of the Heidi it just goes up vertically under full power and is therefore not to much a problem. They all seem to have a narrow margin between climbing very steeply to going into a power dive with very sensitive controls.

I am starting to experiment by mixing the throttle with down elevator. At present I have used 20% down. It is not clear to me if this is linear mixing i.e. 0 throttle 0 elevator. 50% throttle, 10% down, 100% throttle 20% down. Or is it a step change relationship i.e. 1% throttle 20% down. For me it is not as obvious as I would like, by visually observing the results.,

The transmitter is a Futaba 6 EXA.

Any comments from personnel experience will be appreciated

Regards

Erfolg

[Erfolg]

I have tried the lower powered Sagitta with 15% down mixed with throttle. The model did not climb at all, needed up feed in to gain altitude.

I will try 7 or *8%, I am hoping that these values will give a better climb out. I am now starting to think that very little down is really required probably 3 to 4% to obtain a authorities climb, at about 45% to the horizon.

What is the most efficient angle?

I have attached some pictures, so you have some idea about what I am talking about

Regards
Erfolg

[Danny Fenton]

It sounds to me like the motor should be mounted with more down-thrust

[Erfolg]

I am unable to put downthrust in the motors easily (Major surgery).

I have re-flown the models, one now has 5% down and the other 10%. These changes have made a tremendous difference. I will stick with them for the moment.

I am thankful that I resisted the advice that full down may be necessary. I would certainly have been rebuilding.

Thanks for the contributions, they have all been helpful.

Regards
Erfolg