Bull stole from German Third Reich ideas and railway guns. Peenemunde,
btw, had a design for a 15cm EM railgun with all flight projectiles
wind tunnel tested!!!
Repost from 2007:
By 1944 some theoretical research was started at Peenemunde regarding
a 15cm railgun with a rate of fire of 200 rpm using a 100 kW
powerplant and also a 4cm AA-railgun.
Several radical aircraft-shaped projectiles were tested in 1945 for
the AA-railgun but the power supply was problematic. A suitable
battery or condensator had a very high weight (600 -3,000 tons)
the gun immobile.
More on the 4cm gun:
THE ELECTRIC GUN
German Experiment With Electrically Launched Projectiles
A super-high-velocity gun, operating on electrical energy instead of
an explosive propellant, has been a minor scientific dream for some
time. The idea is not new; for it was tried by the French in World
I. But in World War II, a German scientist felt he was so close to a
solution of the problems involved that the German Air Force had
contracted for an experimental electric gun. This gun was to be
capable of ejecting a 40-mm projectile at a muzzle velocity of 6,600
feet per second-far above the velocity of any shell yet fired from a
conventional artillery piece.
Although the gun ordered was not delivered before the end of the war,
a miniature that actually worked was built and tested. Theoretical
calculations, based upon tests made with the miniature gun, led the
German scientists to believe it possible to build an electric gun
capable of tossing a 14-pound projectile to an altitude of 12 miles
To men familiar with the problems of antiaircraft artillery, such a
weapon appeared a godsend. The 90-mm antiaircraft gun of
powder-burning design, can reach only 4.4 miles in altitude in the
same length of time.
Although the problem of electrically ejected shells is an old one, it
has still to pass the research stages. The chief problem is to obtain
a source of sufficient electrical power that will not be all out of
proportion to the size of the gun. Designing a gun did not seem to be
too great a problem, for the German model appeared logical.
The German gun, had it ever been built to full scale, would have had
rectangular barrel 33.7 feet long. The round bore, as designed by the
Germans, is flanked by two, square grooves 180 degrees apart, so that
when the bore is seen from one end, it is the same shape as the
aircraft identification insignia used by the U.S. Army Air Forces.
bore is not rifled. At the extreme ends of the two grooves, an
insulated, copper glide rail runs the entire length of the barrel. It
is through these glide rails that the electrical energy is conducted
for ejecting the shell.
The shell is a cylindrical projectile somewhat longer than the
conventional artillery shell, and has four narrow fins at its base.
is fitted with a cradle, called a "glide wing," from which extend two
studs which fit into the square grooves of the bore, and ride on the
copper glide rails. After the shell has been placed in the gun, a
of electricity is shot into the weapon. The current, passing along
glide rails and through the glide wing, sets up an intense magnetic
field. The reaction is such that the magnetic field and the current
flow through the glide rails tend to repel each other. This, in
effect, forces the projectile up the bore at an ever increasing
velocity until, when it leaves the muzzle, it is traveling at a
terrific rate of speed. This reaction is so fast that it is only a
matter of a split second between the introduction of the current and
the ejection of the shell from the gun.