I thought this would be of interest, a few extracts from a report from the 1940's.
The development of ultra high velocity fin stabilised projectiles in the United Kingdom
Introduction. Some notes taken from report no 5/48 obtained from the public records office, Kew.
The development of supersonic fin stabilised projectiles in the UK had not been seriously considered before 1945. The Germans on the other hand particularly during the later stages of the war did extensive work on such projectiles, the Peenemnde arrow shell.
In May 1945 it was decided that a shell along similar lines should be developed in this country and a directive was issued that a shell carrying at least 1lb of high explosive should be fired within 90 days at a velocity of 5000 ft/sec. This was done. The only way of keeping within this time limit was to use a standard guy to which the minimum number of modifications had been made. Consequently a 5.25 inch barrel was selected and bored out to remove the rifling, being converted thereby into a 5.4 inch smoothbore gun. No changes were made to the chamber the shot seating, the cartridge case or the breech mechanism. Unfortunately the 5.25 inch is a short gun and when bored out the shot travel is only 40 calibres. Consequently the velocities obtained from firings relatively low. As soon as firings with the first type of projectile, the 5.4/2.2 (the second number being the diameter of the body of the projectile) had been carried out it was decided to make a second type with improved aerodynamic performance, the 5.4/1.9.
The 5.4/2.2
The 5.4/2.2 was the first fin stabilised discarding sabot projectile to be fired in this country at really high velocities. It is very similar to the German design but in order for it to achieve high velocities the sectional density was reduced and it was necessary to make the nose and the tail from duralumin. It was not at the time possible to determine the bending stresses to the tail and so the tail stalk and fins were made thick enough to ensure their not collapsing during firing.
The 5.4/1.9
The main difference between the 5.4/1.9 and the previous 5.4/2.2 was an improvement in external ballistics. This was done by thinning the tail fins, streamlining the rear end of the body and by increasing the cross sections density of the projectile. It was during the design of this projectile that a decision had to be taken on the optimum weight to achieve the required external ballistics. The diagram shows that there is a length of body which is made of solid steel and this section has been inserted purely to increase the weight in flight. Without this additional weight the muzzle velocity would be higher but the effect of this is more than compensated for by the reduced ballistic coefficient.
If anyone has any specimens I would be interested in seeing them.
Dave.
The development of ultra high velocity fin stabilised projectiles in the United Kingdom
Introduction. Some notes taken from report no 5/48 obtained from the public records office, Kew.
The development of supersonic fin stabilised projectiles in the UK had not been seriously considered before 1945. The Germans on the other hand particularly during the later stages of the war did extensive work on such projectiles, the Peenemnde arrow shell.
In May 1945 it was decided that a shell along similar lines should be developed in this country and a directive was issued that a shell carrying at least 1lb of high explosive should be fired within 90 days at a velocity of 5000 ft/sec. This was done. The only way of keeping within this time limit was to use a standard guy to which the minimum number of modifications had been made. Consequently a 5.25 inch barrel was selected and bored out to remove the rifling, being converted thereby into a 5.4 inch smoothbore gun. No changes were made to the chamber the shot seating, the cartridge case or the breech mechanism. Unfortunately the 5.25 inch is a short gun and when bored out the shot travel is only 40 calibres. Consequently the velocities obtained from firings relatively low. As soon as firings with the first type of projectile, the 5.4/2.2 (the second number being the diameter of the body of the projectile) had been carried out it was decided to make a second type with improved aerodynamic performance, the 5.4/1.9.
The 5.4/2.2
The 5.4/2.2 was the first fin stabilised discarding sabot projectile to be fired in this country at really high velocities. It is very similar to the German design but in order for it to achieve high velocities the sectional density was reduced and it was necessary to make the nose and the tail from duralumin. It was not at the time possible to determine the bending stresses to the tail and so the tail stalk and fins were made thick enough to ensure their not collapsing during firing.
The 5.4/1.9
The main difference between the 5.4/1.9 and the previous 5.4/2.2 was an improvement in external ballistics. This was done by thinning the tail fins, streamlining the rear end of the body and by increasing the cross sections density of the projectile. It was during the design of this projectile that a decision had to be taken on the optimum weight to achieve the required external ballistics. The diagram shows that there is a length of body which is made of solid steel and this section has been inserted purely to increase the weight in flight. Without this additional weight the muzzle velocity would be higher but the effect of this is more than compensated for by the reduced ballistic coefficient.
If anyone has any specimens I would be interested in seeing them.
Dave.