Maverick is correct. Most, if not all, the heavy bombers default to a minimum flap setting when you spawn on the runway (I can't remember if the JU88, B26 or TBM do or not). Even with flaps notched down, hold brakes until reach max. rpm, push the nose down to get the tail up and use ALL of the runway it is still extremely difficult to get a Lanc or B17 in the air. Adding a few hundred more feet to the runways won't hurt.