Upwards momentum provided by the ramp? Explain that some more.
Question: does the aircraft's speed increase as it climbs the ramp?
Upwards momentum - seems simple enough; if one launches a projectile at an angle it has a vertical velocity component.
And yes, the a/c 'speed' will increase as long as there is enough thrust to overcome the effects of gravity - the steeper the ramp the greater the effect of the a/c's weight. If we imagine an a/c that weighs 60,000 lb and has 40,000 lb of thrust, on a 30 degree incline 30,000 lb of thrust will be needed to act against the weight leaving 10,000 lb to accelerate the a/c. Acceleration = F/M = 1/6. On a level runway all the thrust will act to accelerate the a/c: A = 4/6