Is achievingorbit that easy?

[Anthony]

Originally Posted by Brett

Only if its maximum airspeed exceeds circular-orbit velocity.

Actually, that's not really necessary -- both maximum airspeed and stall speed are inversely proportional to the square root of air density, so you can increase air speed indefinitely by moving upwards. In practice you may need to break out of atmosphere a bit earlier, to avoid being cooked by plasma formation from passing through atmosphere at 3+ kps.

[blacksmith]

Originally Posted by Anthony

Actually, that's not really necessary -- both maximum airspeed and stall speed are inversely proportional to the square root of air density, so you can increase air speed indefinitely by moving upwards. In practice you may need to break out of atmosphere a bit earlier, to avoid being cooked by plasma formation from passing through atmosphere at 3+ kps.

What I wonder is could you use the skipping on the upper atmosphere idea that some hypersonic transports have suggested to gain the lift when airspeed get high enough.