Glider said:
Lunatic. This may be of interest. Its has a lot of info about aircraft weapons and what little I knew matched it. His assumptions are explained and whilst I don't agree with all of them. At least he isn't afraid to explain them so you can make your own mind up.
http://www.quarry.nildram.co.uk/WW2guneffect.htm
LOL - I have two of Tony's books and am a member on his forum. Get his book "Flying Guns of WWII" and you will see that his figures match my figures pretty closely, except where he's generalized too much (he does not go into the different .50 variants very deeply).
I don't know where he comes up with the figures in that chart. The do not match even his own figuers in his book. The following page has very detailed info taken from actual documented gun tests conducted by the Soviets:
http://www.geocities.com/Pentagon/Base/1852/
Unfortunately this page is down for bandwidth right now. When it comes up search it very carefully and save each page you visit that has info you want. It may take several visits to find the relevant data. Somewhere on this site is a page showing cutaways of the various mine rounds and giving the actual tested figures. I believe the 765 m/s figure is even the "best of X rounds tested", as many of the figures on this page are. When I get a few hours spare time I'll de-archive the CD I made of my desktop PC onto this laptop and find the sources and post them. I'm pretty sure those links and info are on this site somewhere in a gun related topic.
The problem is that Tony seems to think every plane was a flying tank and that if you didn't kill it in one or two hits your guns were worthless. The reality is that American planes tended to be tougher than their German counter-parts, and German 13mm guns were rather weak so there is no good way to compare things from actual historic data. Tony and Emannual like cannon, and often point to post-war data to justify their WWII assertions. However, jets are a lot tougher targets than props and post-WWII cannon and ammuntition was superior to its WWII counterparts.
Again, there is no doubt that on a hit for hit basis the 20mm are far more powerful than the .50's. But it is questionable whether one Hs.II round is superior to four .50 rounds (based on RoF of 1 x Hs.II vs. 3 x .50's). Assuming from a given firing solution that 33% of the rounds hit, which would you rather have? To me, scoring 1-2 .50 hits is far better than missing with the Hispano 8)
Glider said:
As for the USA with the 20mm, if you asked us nicely I am sure that we would have helped.
The British did help. But British technical drawings were... not very good. The whole British production methodology allowed for a lot of hand craftsmenship. British hispanos did not enjoy good parts enterchangability. The USA took the design given by the British and screwed it up further, following the diagrams exactly which gave too large a chamber clearence resulting in the firing pins not reliably striking the primers on the shells. The british tightened this clearance up but not until after they delivered the drawings. Furthermore, the US considered the 20mm a cannon, and built it according to artillery tolerances rather than rifle tolerances, causing even more slop resulting in an unreliable gun. Eventually these problems were worked out, but not until the war was nearly over.
Even the British Hispano was not very reliable by US standards. Early models were notorious for jamming, and even toward the end of the war the jam rate never got below 1:1500 rounds. At the start of the War the .50 jam rate was 1:4000 rounds. This is why the Spitfires carried a pair of .50's as backups until the last year of the war.
Glider said:
Les
As for your last question 'and the winner is?' its the Hispano V. But you wouldn't expect me to say anything else!!
Well, there is a down side to the Hispano - It was a large and heavy gun requirning a very sturdy mount. The Spitfire had trouble mounting it since it required 3 mounting points and relies on those mounts for structural ridgity. If they flex too much the gun will jam. This required serious redesign of the Spitfire wing. Furthermore the recoil is severe and this tends to reduce gun accuracy.
In my opinion, for a Fightger vs. Fighter gun the clear WWII winner was the Soviet B20. This gun was light, had a high RoF (800 rpm), fair velocity (800-850 m/s), the explosive rounds carried up to about 7 grams of HE, and it had good reliability. A P-51 could easily have mounted six B20's with 300 rpg, and that would have been awsome fire power!
Against bombers... well it's hard to argue against the MK108!
=S=
Lunatic