Originally Posted by
Miniflyer
The full scale engine is about 3.8m long (sorry for metric). At 1/4 its just short of 95cm scale engine length. Presuming an average distance to exhaust/intake at around 10cm and an average engine length of about 25cm, will give about 50cm mounting range for cg of engine. Looking at the wing geometry the cg should be about mid-engine.....we are talking leverage of +/-25cm (under 1 foot) for a weight shift of (total for 2 engines) under 2kg (4.5lbs).
Fuselage geometry indicates weight can be mounted about 1m in front of cg.....estimating 250g per thrust tube indicates 500g of thrust tube weight total
Basic leverage math:
removing thrust tubes and mounting engines aft will require addition of 125g of lead in the nose. Yes. BUT you can remove 500g of thrust tubes. Overall you will gain 375g weight. Now by smartly rearranging your equipment you can eliminate the lead, fly lighter and have more thrust available......while gaining all the other advantages for free....
Yes you are right , but the front position of the turbine is much much comfortable also in any cases I will have carbone fiber tubes in the wing , because the wing will be by three pieces in any cases .
The CG is also + in my desition.
Thank you very much for your very interesting and constructive posts !
Another one , Any builder who want to move the turbine back is free to make it , in the engine area have much space to move the jet where you want
