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It is possible to get the velocity with a rail gun, where the projectile is powered by electric and magnetic reaction. Major limiting factor for launching to LEO is the required mountain to build the straight vacuum chamber needed to get the power requirement down. You just need muzzle velocity to be greater than 10km/s then it will be in orbit pretty soon. The need for a mountain is mostly for noise abatement, the sonic boom will be pretty big. It will really only be usable to launch mass, any person launching with it will be a puddle on the floor.
BC explained that there is a limit to the speed that molecules in the propellant are moving (speed of sound).
Quote from: imatfaal on 14/07/2012 17:37:29BC explained that there is a limit to the speed that molecules in the propellant are moving (speed of sound).There is a trick that Bull worked out; if you apply the hot gas sideways at carefully timed moments you can go above that. You need a wedge shaped sabot behind the projectile though and apply the force at an angle.The other way to go is to use multiple stages, like a light gas gun; if the gas is already moving at high speeds being pushed by a piston when you light it, then it's going to go supersonic (higher than the sonic speed of the hot gas).
HARP used a non-rocket spacelaunch method based on a very large gun to fire the models to high altitudes and speeds....The project was based on a flight range of the Seawell Airport in Barbados, from which shells were fired eastward toward the Atlantic Ocean. Using an old U.S. Navy 16 inch (406 mm) 50 caliber gun (20 m), later extended to 100 caliber (40 m), the team was able to fire a 180 kilogram slug at 3,600 metres per second (12,000 ft/s), reaching an altitude of 180 kilometers (591,000 ft). In 1966, the HARP gun fired a projectile to 112 miles high, a world record that still stands.
Projectiles go furthest in the horizontal plane for a given muzzle velocity when fired at 45degrees to the horizontal (although I think this angle ignores air resistance) - but the muzzle velocity itself is independent of the angle of inclination.
As far as I am aware a gun can achieve it's greatest velocity when fired at an angle of 45°. If this is the case what speed and distance would the projectile [that reached an altitude of 112 miles fired at near 90°] have attained had it been fired at 45°?
Quote from: RE.Craig on 12/02/2013 04:26:44As far as I am aware a gun can achieve it's greatest velocity when fired at an angle of 45°. If this is the case what speed and distance would the projectile [that reached an altitude of 112 miles fired at near 90°] have attained had it been fired at 45°? As far as I remember a gun will have it's greatest range , for a given muzzle velocity, when it's at 45 degrees (assuming a few things, notably a flat earth).If I wanted the greatest muzzle velocity, I would point it down. gravity might not help much, but it would help.In the real world, the usual model* for range doesn't work terribly well. The biggest problem is that it ignores air resistance.If you are trying to ram air out of the way at hypersonic speeds, air resistance is hugely important.45 degrees is no longer the "right " answer and a calculation of the range isn't going to be very good.As an indication, the (lower bound to the) velocity I calculated for the HARP projectile was 1700 m/s. The real speed was about twice that.* Like thishttp://en.wikipedia.org/wiki/Trajectory#Uniform_gravity.2C_no_drag_or_wind [nofollow]
I would imagine they fired the gun at 55* to prevent overshooting the target and not because different laws of physics apply to German artillery!!!
For 45° not only must the Earth be flat but it must be infinite in extent.
during WWII about 8 shells coming from the south landed on Maidstone about 65 miles from the nearest German occupied territory apparently 21cm missiles from a K12 they had not lost their enthusiasm for experimenting with long range guns.
There was no was psychological damage in Maidstone as we were just told they were anti aircraft shells that had gone astray but I knew better as at one location you could see where the shell had come thru the branches of a tree on its way but during the war you believed what you were told to believe !!PS this happened the day before the first V1 came over.