Davparlr said:
You can have the last say.
I guess I lied.
HoHun said:
I don't think the British had any choice in the fall of 1943 - beggars aren't choosers. Pressure towards standardization was considerable, and the British happily went along with it because that was the way to get the US to make some specifically British requirements part of the standard too. There was no middle ground - it would have been either all Mustangs with 20 mm cannon, or all Mustangs with 12.7 mm machine guns. No way get the USAAF to agree to cannon, so - machine guns for the RAF.
I think this statement is unsupportable. The British were not shy in upgrading American equipment in order to improve them per their concept, which were usually good. For instance, they upgraded the P-51 with the Malcolm hood to improve visibility, did their own Merlin upgrade trials, and they also added rocket launchers. They also had no problem upgrading the Sherman tank, which was really a "standard" weapon, with a much more powerful gun because the 75 mm was not powerful enough. You are asking us to think the British Army could make the Firefly out of the standard Sherman (they built about 2100 of them) but the RAF and the RN was not able to upgrade the P-51, F4F, and F6F for the same reason. I do not believe that is reasonable argument.
What the British really thought about the Mustang's 12.7 mm machine guns' firepower is explicitely stated in the report I quoted above - "very little compared with the Spitfire".
Remember that was with the four gun P-51B. Also note that they said it was "very little compared to the Spitfire", they did not say it was insufficient, which I am sure they would have said had they thought so. Also, here is a quote from "Mustang" by Robert W. Gruenhagen, which seems to be a pretty good book. This is a reference to the P-51B operations of the 2nd Tactical Air Force of the British Air Arm after receiving the plane.
"Soon after the aircraft was put into service, several reports were sent to Boxted concerning the deficiencies discovered with the use of the airplane. Propeller seal leaks, gun jamming, engine oil breather problems and oxygen system failures were the main problems encountered."
There doesn't seem to be a note about the ineffectivity of the 50s, and the British were also quite familiar with the 20mms. If they agreed with you, you would have thought they would have said something like "We need more firepower".
The decision to accept the 12.7 mm armament was a strategic one and ran counter to better knowledge of the tactical value of the machine-gun battery expressed in the technical reports.
But not supported by tactical reports.
Actually, Project GUNVAL proved that the USAF felt the need very keenly right in the middle of the Korean war when their 12.7 mm machine guns proved lacking.
I didn't mean to imply that the need was not felt during the war, only that the 20mm was not implemented until after the war for the AF.
I can assure you that during 29 years of design engineering and managing, I have had many a sound argument lost to test pilots/warfighters. They carry a lot of weight, especially when someone wants to change something they have that works. I must admit, however, if I had won one my arguments, we might have lost a B-2. I didn't really fight very hard and we settled on a happy compromise, but that is another story. By the way, I won almost all of my positions, but I had to win over the pilots.
The "guy in the cockpit" probably didn't even know that he could have had the same firepower for his P-47 at 500 lbs less weight - or did you ever find the 12.7 mm machine gun praised with words to the effect "worth every of the 500 lbs of their extra weight and more"?
I bet those Brits in the P-51 understood all about the 20s and were still silent. It is also interesting to note that at the 1944 Fighter Conference, that there were quite a few RAF and RN type and the biggest comment they had when discussing the 20mm vs the 50 cal, was "they liked the 20mm", but none from the RN guys stated their desire for the weapon or the weakness of the 50 cals. If they were as passionate as you are about the advantages of the 20mms, you would have thought they would have stated so when asked at a conference comparing operational performance of fighter weapons systems.
Just contemplate the number of pilots that were lost through lack of performance, lack of manoeuvrability or lack of fuel brought about by the 500-something pounds of extra weight incurred by the overweight and underpowered 12.7 mm machine guns. If a weapon needlessly weighs you down enough to get you shot down, it has failed you. If the extra weight is inevitable, nothing one could have done, but if it's result of poor technology ... well, someone screwed up somewhere.
All you have is contemplation. You have never provided information such as kills/engagement, sorties per kill, or even probability of kill comparison of a three second burst in multiple scenarios and on average. These are the type of variables that must traded off against production line interruptions, delivery delays of critical assets, logistic cost, etc., for a decision maker to overturn or argue to change the desires of the warfighter who have not been complaining. All aircraft have compromises that affect performance in some manner. You have no idea how many lives would have been saved, if any.
You're comment that ""probability of strikes" is completely secondary to the "probability of kill"" is confusing. If you have a Pkill/strike is 100% and your Pstrike is 0, your probability of kill is 0. It looks to me that the probability of strike is vital to probability of kill, not secondary.
but you're again ignoring the possibility that such a decision could have been made early enough to avoid all the failures that historically surrounded the US adoption of the Hispano cannon.
I did not ignore it. I stated before that it wasn't until late 1940 before the British started to update to the 20mm. At that time, the US had multiple platforms in production and in development. In addition, they had established production lines, logistics and maintenance systems. Also, there was no operational report that the 50 cals were not effective. I am sure that there was not a production facility ready to produce the thousands of canons per month required to supply the rapidly increasing US production capability. Any available production facility, such as an automobile plant, would require tools to be manufactured and personnel to be trained and supply line established. All of this would have taken months to get up to speed. The aircraft builders would have to design and build tools, establish supplies, and pull workers off the production line to train in installing the new equipment, which would have delayed aircraft production by at least three to six months, when aircraft quantities were critical, especially to the British (most likely, the F4F-4 with 20mm would not have been available for the battle of Midway, which they barely made anyway). All of this with no indication of the effectivity of the 20mms, or whether the 20mms being built were going to work, and, again, NO indication that the 50 cals were not effective, because they were.
The numbers argument doesn't really cut it anyway since one cannon could have replaced about three machine guns, and with a timely ramp-up of production, there would have been no "quantities unavailable" like your argument implies. The "arsenal of democracy" could hardly be overtaxed with producing a couple of thousand cannon when it was capable of producing an abundant number of obsolete machine guns.
Numbers was never a problem except in start-up time. If the decision was made in 1938, I am sure the 20mm would have been incorporated flawlessly, but it wasn't.
The silence of the British when addressing the 50 cals on American fighters is deafening, there seems to have been very little complaint.
By the way, I saw that the 2nd Tactical Air Force flew P-51III and Spitfire IX at the same time. It would be interesting and informative to this argument to learn the kills/engagement of each. The P-51III was somewhat similar to the Spit IX, but their mission may have been different.