Back in the 50's when no one knew if spaceflight was even possible,
several tests were made with sounding rockets launched by balloon at
high altitude. However the payload capability of even very large
balloons declines at extreme altitude, and launching a large balloon is
tricky. Because of the long period climbing to launch altitude
cryogenic propellants were not practical. Ultimately it was not
possible to carry rockets capable of getting into orbit. A similar
problem will occur with rotorcraft.

On the other hand, a fixed-wing aircraft.i.e. the B-70, can indeed be
designed to carry a large payload at high altitude. While a large blunt
cone would have to much drag for external carriage on an aircraft, a
saucer-shaped vehicle could be carried and launched edge first and
re-enter flat side first; this is pretty much what Rutan's SpaceShip
One does with its pivoting tail. This can spread the heating over a
large area as with the Apollo Capsule, reducing thermal loads.