If we, for example, take RoC as the time taken for a change in altitude once the aircraft is airborne, ignoring any effect of height or wind speed or other variables and assuming a fixed load. And consider maximum possible rate of climb, for however short instance that might be and under whatever circumstances that might be achieved. Now if we increase speed, we also increase drag but can have a high initial velocity going up against gravity; if we decrease speed we decrease drag but with a lower initial velocity. So there must be a point where a plane can have the highest initial velocity with minimum drag with full thrust. Brakes off to 40,000 ft is useful but what does 300m/s signify ?
