Air rocket
A compressed air rocket is a rocket , in which compressed air as energy storage is used. The physical principle is based on Newton's 3rd law, known as the reaction or interaction principle ( Actio and Reactio ). Drives that function according to this principle are called cold gas engines and are used in a wide variety of spacecraft .
Recoil principle
According to the recoil principle, a force acts on a body when it is thrown away from it:
(in Newtons )
It is the reaction force, the mass. which flows through the nozzle per unit of time (in kg / s) and v is the outflow velocity in m / s. The force generated is opposite to the outflow direction. Basically, all missiles work according to this principle.
Pure compressed air missiles
In pure compressed air missiles, the compressed air serves as an energy store and at the same time as the only medium that is ejected backwards (as a recoil medium ). The most primitive form of the compressed air missile is an inflated balloon, the opening of which is closed with the hand and which rises when released by the recoil caused by the outflowing air.
Increase in performance
One way to increase the performance is to add liquids (usually water ), which are then forced out of the nozzle by the pressure. Although this reduces the volume that is available to take up the compressed air and thus to store energy , the recoil force is increased enormously by increasing the mass throughput . Such modified compressed air missiles are called cold water missiles.
Web links
- Michael Jasmund: Technology and construction plans> Water rockets. on mjasmund.de
- Header - Why does a rocket filled with water and compressed air fly further than without water? on DasErste.de (December 14, 2012)
- Air pressure rocket on nick.de (handicraft instructions)
Individual evidence
- ↑ Air rocket. Deutsches Museum, accessed on May 15, 2016 .
- ↑ LP - water-to-air missile. lp.uni-goettingen.de, accessed on May 15, 2016 .