RE: 42"wingspan p51d what size engine?
I have three House of Balsa p51s with 30 engines,two with 30 enya two strokes and one with a Magnum 30 4stroke. Each weighs just under three pounds and fly great. The enyas fly fast,a little over 90 mph but the 4 stroke is much more fun.By moving the firewall back and mounting servos in the tail I was able to keep the same overall weight as the two strokes.I enjoy building and thought this would be something of a challenge. I am glad to see someone else still likes the smaller planes.Most of my club has gone to 3d and larger than 60 size planes.
I also have a Birdie 10 with a 15 enya that flies as well as the big ones.