Rockoon
A rockoon ( English from rocket and balloon ) consists of a rocket carried into the high atmosphere by a gas-filled balloon , which for practical reasons is usually equipped with a solid propulsion rocket . This is ignited when the balloon has reached its maximum height and separated from the balloon. Since the rocket does not have to move through the dense layers of air, it can reach a greater height when used on a rockoon than when launched from the ground. The lower air resistance enables rocket designs that save material and mass, for example shorter length and larger diameter. At an altitude of 36 km, the air pressure is only around 1% of the air pressure on the ground. Therefore, the cross-sectional area of the expansion nozzle can be up to 100 times larger (10 times the diameter of the outlet opening) than at a height of 0 m, which enables a higher efficiency of the engine and comes close to the vacuum thrust .
The disadvantage of the Rockoon is that the missile cannot be precisely aligned, which is why, for safety reasons, a large area must be cordoned off for the missile's companionway. Also, no target-seeking missile can sensibly be fired with a Rockoon, which is why the Rockoon has no major military significance. Because the balloon cannot be steered, it is also difficult to determine the place of descent of a payload capsule to be salvaged. By using thrust vector control , inertial navigation systems and global positioning systems , these disadvantages have recently been compensated for.
The Rockoon principle has been used for the Low-Density Supersonic Decelerator since 2014 .
Web links
- Rockoon in the Encyclopedia Astronautica (English)