Impacts (and maybe other airplanes, too) seem to require a higher vertical CG with electric.  I had to move my battery up 5/8". 

Was it the same upright and inverted or opposite when you went inverted?

What you are describing could be torque roll.  Reverse the motor and get a puller prop and see if it rolls the other way.  If it does then you know its torque roll.  If not then you know its Vertical CG.  Knowing which one it is would help you correct it.

If it is torque roll my theory is the electric motor is a constant torque on the frame where the IC is pulsing with each fire and a flywheel effect with the counter balance on the crank shaft is taking some of it out.

A way to correct this would be a tab on each wing to hold it level. I would use a tab separate from the flaps as far out as possible.  When you adjust one up you adjust the other down and so on.  That along with the adjustable guide height and you should be golden.  Just be ready when it quits it will want to roll back into its natural trimmed state in the glide.  

Just my thoughts on it...

Others, like Robert says below, are having great success fixing this by moving the battery so it's likely it is just VCG.

Paul,
The electric pusher option does bring up some area's that could be refined over IC power. Since the torque on the pusher wants to roll the ship counterclockwise some of the normal trims that get built-in (positive incident on stab, high engine mount to distribute the engine weight vertically) can be looked at and tweaked. With electric we have the advantage of being able to adjust the vertical CG with the battery (you do need to allow the battery holder to be adjustable in both vertical and horizontal directions).

I agree with Robert you more than likely need to lower the battery to level the wings with the pusher prop setup, other option is to put on heavy wheels if you can't move the battery. If you change to a tractor setup you may need to go up.

Best,          DennisT

(snip very good info above)
As always, it's easy to try the tractor prop and compare. You have to love that about e-power.

Regards,
  Dean P.

Yes that is so cool about E-Power!!   

Impacts (and maybe other airplanes, too) seem to require a higher vertical CG with electric.  I had to move my battery up 5/8". 

Howard, when trying to quantify torque in level flight, I have found this (Pusher):

My log shows 360 Watt Motor Power In at 9'500 RPM. Assuming that 360 Watts Power In comes to approx. 270 Watts Power Out, the torque in level flight should be 0.27 Nm or 2'753 Gr/cm or 38oz/in. (Approx. 60% more in tight manoeuvres)

Seems to be quite substantial. Is this plausible?
rgds. Peter G.

hi guys my plane has ajustable wing tip flaps  and a ajuster in the main flap i incorparated this item to account for gradual warpage with age all the above has been used to make the plane fly well as suggested i have prepared a tracter prop of the same diameter and pitch and wheight  but i am now being held up by the british autum weather also i have one team selection left to fly so i will leave the trim alone till then        i think that deans suggestion of spraling air flow is probally the anser  i will check so watch thiss space   roy cherry

hmm ... small question, why you want ballance almost constant motor torque by variable torque comming from variable force comming from centrifugal force minus variable gravity vector? ... we can make almost constant torque from twisted flaps which can easily ballance torque of the motor

hmm ... small question, why you want ballance almost constant motor torque by variable torque comming from variable force comming from centrifugal force minus variable gravity vector? ... we can make almost constant torque from twisted flaps which can easily ballance torque of the motor

I moved the battery to cancel the variable torque coming from the variable force coming from centrifugal force (and other line tension sources) minus variable gravity vector.  I don't know why the optimal vertical CG differed between IC and electric power sources. 

Thank you for putting your calculation into our quaint American units of measure, not to mention your accommodating our monolingualism. I felt obligated to do some ciphering. 

Yes, I got the same numbers for motor torque.  The rolling moment (torque) change per inch of battery height for my 375-gram battery on 70-foot lines doing 5.4-second laps in level flight is 39 inch-ounces.  Raising the battery 5/8 inch would have changed rolling moment by 24 inch-ounces = .172 Nm.  This made more difference in how the airplane flew than the 76-inch-ounce change from changing the prop rotation direction.  I reckon the swirly-air moment must concel the motor torque pretty well.  Now how does all this vary as speed and angle of attack, and why did I have to raise my battery?

Could it be the (pusher prop's) P-factor?

Igor, my log says motor power (watts) being approx. 1.7 times higher in climb. At constant RPM, this should translate into 1.6 time more torque, too.

psssssst  ... otherwise someone comes and invents servo controlled compensating trimming tab (actually easy doable as well as electronic rabe rudder) ... and soon we will have flying computer 

yes I know ... I mean constant because constnat rpm torque variation is not so large, imagine that my active timer add 1000 rpm uphill :- )))) ... and I still do not feel any need to compensate it any better then twisted flaps do

I think the only way to make neutral model from its concept, is landing gears down, motor and thrust line over the wing with tractor prop 1/ ballancing mass of landing gears by weight of motor and battery 2/ precession of tractor prop by negative moment from drag of landing gears and thrust line over the wing AC ... and that is how my latest model is designed

inline model will work, but it will need several tricks, but I do not see reason to do it if thrust line over the wing works so well

Forget about torque..............just do it like the model below 

Keith R

avery interesting veiw form Yurli Yetsenko




Yes,  the  torque  of the prop acts to the inverted direction from the
prop rotation. If you will change the prop to another direction of the
rotation, you will feel another direction action. The action of a prop
have 2 separate actions, gyroscopic and aerodynamic  drag of a blade.
Both creates torque to the same direction. When the engine stops, this
torque  disappears.  It is possible to reduce the gyroscopic torque by
the different prop and a motor rotation (see the picture) providing.
However, this modification do not exclude the aerodynamic component of
a torque. The single way to reduce it it is to create the coaxial prop
power plant. 2 ways. The first it is a separate shafts driving by tooth
wheels and a tooth belt for a different way of rotation creating. This
way  do  not exclude the gyroscopic  torque. But with the constant RPM
the  gyroscopic  torque  have "0" action, it acts just when you have
the acceleration or reduce of an RPM. If you fly constant RPM,
you  have  no  action  of  Gyroscopic  moment to the model in straight
flight. (just for active timer with the RPM change it is important).
However,  you  have the Coriolis  torque action, if the model
change  the  direction of a flight from the straight. Every corner the
model  feels  this  action,  also  in  horizontal  flight, because the
horizontal   flight   is  not  straight,  but  round.  If you turn the
rotates bicycle wheel (hold it for an axis both sides from a wheel)
you  will  feel  this  torque  action  and  its  direction.  You  will
understand,   why   sometimes   the   model  reaction is not logic and
different   (asymmetric)   in   some   points of figures, sometimes it
reduce the lines tension, sometimes opposite. More weight of a
rotating  mass,  more diameter, more RPM - more action. That is why so
important  to reduce the mass of a rotation parts. Or to compensate it by
an opposite rotation mass action.
The  third  version  total compensate all torque elements that acts to
the   model   in   flight. But it is heavier and it needs special flat
motors with a low RPM capacity.
Coaxial prop have 20-30 % more thrust capacity. It is an advantage.
I plan to produce this versions for Gee Bee in
future, I need time, money and the energy to do all this faster. I try
to work hard, but my time is limited, this is the question now.
Thank you.
Best wishes.


 Yuriy