Hi,
During my recent Giro developements the initial problem was the
craft tilting at lift off time of the take off run.
Full scale Giros would be tough to hand launch, so they all have
had to take off themselves. If our objective is to emulate full scale then take off is a primary part of it
To cure a problem one needs to know what it is and the cause. Research found the tilt was caused by retreating blade stall, more precisely a differential in lift between the advancing and retreating blades.
A rotor accelerates from zero RPM to flight RPM. In that process a point is reached where sufficent lift is present to leave terra firma even though flight RPM has not been achieved, It is in this RPM spectrum that retreating blade stall occurs. Fortunately the spectrum is small and is not present during flight
The obvious solution to no tilt take offs would be to get through that RBS spectrum quickly, full scale learned to do it by prespinning the rotor, that should work for models also if there was a means.
Happily a simple means was found. We wind the prop up to start the engine why not wind up the rotor to start take off?
Proved to be easily done, add a prop spinner to the blade hanger, use the engine starter motor or better still a power drill and simply wind the rotor up. Question could be how many RPMS is sufficent, Easily determeined. Use wind to wind up the rotor, tach the RPMs, the speed where lift starts to occur would be the minimum spin up rpm.
Proof of the pudding? Since using prespin for 100s of take offs there has not been one abort of any kind!
Hope I have been of some help, do have fun !