Posted: Wed Jan 09, 2008 11:22 am
aah sorry about that. Take it magnesium on the points wont work either?
Yes, there are, but it needs some serious building. DYI summed up the various ways quite nicely here (ordered hardest to easiest):Spitfire wrote:are there guns that can shoot projectiles faster than the sound barrier?
I suggest if you're considering it, methods 5 and 6 are probably more where you should be looking (as most successful supersonic launchers use such methods), but there are reported cases of people using enough brute force to achieve 3, and 4 might be within reasonable practicality limits (I suppose a steam cannon is a mix of 4 and 6). There are only two people I can think of who are mad enough that they are trying to build a launcher that uses method 2, and 1 is almost completely impossible.DYI wrote:1. Somehow achieve a valve with a frictionless inside, as well as a frictionless barrel which is evacuated of air before the shot (which requires a vacuum pump). Can't get more than 500 m/s.
2. Ye Olde Plasma Rifle; Turn the gas into a plasma by heating with extremely large electrical discharge in the chamber. According to one resident genius, could conceivably achieve velocity in excess of 7 km/s if aided by magnets to guide and concentrate the plasma. Not recommended for beginners (or anyone, really).
3. Use massive amounts of pressure, and a very fast valve, to solve the problem by brute force like the AirForce Condor air rifle. Still can't pass the 500 m/s limit though.
4. Heat the gas, either by shock compressing it with a piston, or by increasing the chamber temperature with a heating apparatus. The heat achieved must be very significant to add any meaningful performance. (Several hundreds of degrees fahrenheit above room temp.)
Velocity is limited by the heat achieved.
5. Build a hybrid. The particle speed in the post-combustion chamber is about 3000 ft/s in most cases.
6. By far the simplest of them all: Use a gas with a higher particle speed than air, such as helium or hydrogen (helium is a better choice for a beginner, as using hydrogen has loads of inherent dangers). The speed of sound problem will not be encountered in helium until about Mach 3, and not in hydrogen until ~Mach 3.8. Requires no heating, no evacuated bore, no specialist valve design, and no complex gas mixing.