Coffee time so:
Empirical data and experience suggests you dont need two mighty servos on a Mig 29. The Su. MAY be different but :
My Mig on which the stab has forward pivot point ( with consequent effect on aerodynamic balance) first flew with two JR 8411 servos. ( 12kg/cm) Current draw by the stabs. measured by the Weatronics, was very modest suggesting low servo load.
When the JR 6311 servo, (36 kg/cm) with twice the power of the 8411 s arrived, I replaced the two 8411 halving the risk of failure and simplifying installation. Again, current drain low, measured in flight, not guessed.
On the flight which suffered flutter ( which can create massive stress) the servo on that stab. the 6311,. Suffered NO damage to splines or gears and is now back in use on another model. Resolution and smoothness was unaffected.
The only damage by the flutter was to the stab. round bolt holes became oval but there was sufficient control to land safely.
Now the Mig has been overhauled the brilliant Futaba 700 with 70 kg/cm has replaced the 631s, one on each stab.
The huge torque is not required to move the surface, but the superbly tight gearbox and high torque will be highly resistant to flutter.
The 6311 metal gears ( brass ?) suffered no damage despite the violent flutter, so the 700s with a stainless steel output will I guess, be more than adequate. After the flutter experience I have no concerns.
Anyway the refurbished Mig is serviceable and will be flown soon and again, currents caused by servo defection, will be measured by the Weatronic Gizmo, and analysed.
I pass on this experience for what, if anything, its worth !
Coffee finished !
Last edited by David Gladwin; 09-02-2020 at 12:43 AM.