ORIGINAL: tIANci
If you are talking a kinda standard jet plane and not something like a U2, you can try to shoot for a thrust to weight ratio of about 0.7 ... 0.85 would be very nice. So if the plane is 1kg, you want to try to get about 700g of thrust.
so if i put an 64mm EDF whith a motor which produce 520w and 1100g of thrust i will be ok in 1kg plane??
the kind im going to built is an L-39.