Hi Otto,
your first point: could we discuss this in private email?
Different engines: I saw the model fly with two different saito's, with good effect. I thought about ball bearings, but this has to be really balanced, I've never heard of "harmonic balancing", sounds interesting, but heavy... Do you know an URL where I can inform?
Electric fan: Otto, if you read this whole thread through, the fan is becoming very famous... I would like to see a pic of it; though it all sounds very heavy, and I can't use this at the tailside...
If someone has an option, I would be very happy to hear about it.
Overheating: I thought I had a solution during flight with an air channel through the airscoop, via engine to outlet holes, but didn't think about the so fast overheating on the ground; doesn't this apply for the normal front engines too?
thank you very much, good research is half the work...