Yet another .50 vs 20mm thead.
- Thread starter Shortround6
- Start date
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Edgar Brooks
Senior Airman
They did both (at least.) Shots were fired at hulks, sheet metal, armour (not just German,) from different ranges and different directions. It was found, for instance, that even the .5" could be deflected by the taper of the fuselage, if fired from directly behind, and, in the Fw190, the (retracted) tail wheel gave added protection (plus all of the "furniture" behind the pilot's seat,) even before it reached the armour.
I've found nothing, so far, about guns, which could not be made here, being tested, but it begs the question, what would be the point, if they couldn't be used?
The "de Wilde" ammunition was a red herring, since it was not used; the name was used as a cover for a newer, better incendiary type of ammunition, invented here.
Tracer was rarely used, since the sparkle of the incendiaries was found to be most useful for gauging when hits were being achieved; at night it destroyed night vision but had to be used in bombers to give gunners a visual clue. When "Village Inn" came into use, right at the end of the war, it wasn't needed, any more, for the bombers.
The .5" was 12" longer than the .303", so could not have been fitted as a one-for-one replacement; in the Spitfire the outermost compartment cover had to be bulged, slightly, to accommodate the rear of the body of the .303".
Always bear in mind that it was thought unlikely that single-engined, high-speed fighters would be encountered over the U.K; Sholto-Douglas held out against fitting armour behind the Spitfire pilot, because he said that it was the fastest thing in the air, so nothing would be able to get behind it, unless the pilot made a mess of it.
Edgar
I've found nothing, so far, about guns, which could not be made here, being tested, but it begs the question, what would be the point, if they couldn't be used?
The "de Wilde" ammunition was a red herring, since it was not used; the name was used as a cover for a newer, better incendiary type of ammunition, invented here.
Tracer was rarely used, since the sparkle of the incendiaries was found to be most useful for gauging when hits were being achieved; at night it destroyed night vision but had to be used in bombers to give gunners a visual clue. When "Village Inn" came into use, right at the end of the war, it wasn't needed, any more, for the bombers.
The .5" was 12" longer than the .303", so could not have been fitted as a one-for-one replacement; in the Spitfire the outermost compartment cover had to be bulged, slightly, to accommodate the rear of the body of the .303".
Always bear in mind that it was thought unlikely that single-engined, high-speed fighters would be encountered over the U.K; Sholto-Douglas held out against fitting armour behind the Spitfire pilot, because he said that it was the fastest thing in the air, so nothing would be able to get behind it, unless the pilot made a mess of it.
Edgar
Jabberwocky
Staff Sergeant
I've read that US 20mm ammunition was problematic in several sources, but none of them seem to mention why this was so. Anyone have any more on this?
As for the RAF comparative tests of the .303/.50/20mm. The 1939 tests were conducted against plain high hardness roll homogenous steel armour (IT 70) without any intervening barriers. The were done at 0, 20 and 40 degrees.
There were other tests done against RAF bombers and crashed/captured Luftwaffe that tested penetration through intervening aircraft barriers, such as fuselage skinning and internal stringers.
There were several different sets of tests carried out against 109 fuel tanks.
The early tests found that these German self-sealing tanks (at least those found on the 109E) were vulnerable to pretty much everything fired at them, although most vulnerable to the 20 mm. Keep in mind that this is before deployment of API for the .50 cal, but tested with .303 API.
The early German self-sealing tanks had 5-15 mm of various types of rubber, with canvas/leather and aluminium layers. There was also a 8mm dural bulkhead (10 layers of 0.8 mm sheets) protecting the fuel tank for the 109E-4 onwards, which was somewhat haphazardly retrofitted to earlier production aircraft.
Of course, WW2 in the air was a technology race and later tests on the tanks in the 109F and 109G come up with a different conclusion. The tanks were much better protected – in addition to a 16-24 mm laminated bulkhead (20-30 layers of .8 mm dural), there was generally a 15 mm lining and sometimes an additional 5mm layer covered in thin plywood.
The tests found that these tanks were almost immune to the .303 and had much reduced vulnerability to .50 ammunition. The dural bulkhead was almost proof against penetration by .303 API beyond 150 meters or if there was any appreciable off angle or yaw.
Of course, there was a penalty: The weight of the 109's fuel tank rose from 58 lbs in the late Es to 121 lbs in the F2/4. The dural plate weighed up to 66 lbs. Interestingly, there is a report on a captured 109G-14 where there was no self-sealing fuel tank, and no other armour, just a plywood box (!) for protection.
Personally, I think the Air Ministry had the right idea in the .303 vs .50 cal stakes until about mid/late-1941, by which time armour protection had risen to such levels that the .303 was pretty inefficient and should have been phased out in favour of the .50.
As for the RAF comparative tests of the .303/.50/20mm. The 1939 tests were conducted against plain high hardness roll homogenous steel armour (IT 70) without any intervening barriers. The were done at 0, 20 and 40 degrees.
There were other tests done against RAF bombers and crashed/captured Luftwaffe that tested penetration through intervening aircraft barriers, such as fuselage skinning and internal stringers.
There were several different sets of tests carried out against 109 fuel tanks.
The early tests found that these German self-sealing tanks (at least those found on the 109E) were vulnerable to pretty much everything fired at them, although most vulnerable to the 20 mm. Keep in mind that this is before deployment of API for the .50 cal, but tested with .303 API.
The early German self-sealing tanks had 5-15 mm of various types of rubber, with canvas/leather and aluminium layers. There was also a 8mm dural bulkhead (10 layers of 0.8 mm sheets) protecting the fuel tank for the 109E-4 onwards, which was somewhat haphazardly retrofitted to earlier production aircraft.
Of course, WW2 in the air was a technology race and later tests on the tanks in the 109F and 109G come up with a different conclusion. The tanks were much better protected – in addition to a 16-24 mm laminated bulkhead (20-30 layers of .8 mm dural), there was generally a 15 mm lining and sometimes an additional 5mm layer covered in thin plywood.
The tests found that these tanks were almost immune to the .303 and had much reduced vulnerability to .50 ammunition. The dural bulkhead was almost proof against penetration by .303 API beyond 150 meters or if there was any appreciable off angle or yaw.
Of course, there was a penalty: The weight of the 109's fuel tank rose from 58 lbs in the late Es to 121 lbs in the F2/4. The dural plate weighed up to 66 lbs. Interestingly, there is a report on a captured 109G-14 where there was no self-sealing fuel tank, and no other armour, just a plywood box (!) for protection.
Personally, I think the Air Ministry had the right idea in the .303 vs .50 cal stakes until about mid/late-1941, by which time armour protection had risen to such levels that the .303 was pretty inefficient and should have been phased out in favour of the .50.
CobberKane
Banned
- 706
- Apr 4, 2012
What was it with American manufacturing and the 20mm? They seemed to do everthing else great. Question for the factory managers: those guys on the production line, the blue-eyed blonde ones who were alway humming 'duetschland uber alles' while they worked - did you ever wonder if maybe...
- Thread starter
- #45
Shortround6
Major General
It had very little to do with the people on the production line and lot to do with the people setting the "standards". Certain dimensions were changed or tolerances allowed. The 20mm fell into the "cannon" category of ordnance which was allowed looser tolerances than "small arms" like machine guns.
Glider
Captain
My best guess is that money was behind it.
Glider
Captain
That may be the official reason but at the end of the day the wretched things didn't work. They knew what changes needed to be made as the UK had been through this learning experience and were almost begging them to make the changes.
Aso the changes that were needed had nothing to do with tolerances, there were some basic design changes such as the size of the breach. It also doesn't explain the problems with the ammo.
- Thread starter
- #48
Shortround6
Major General
You are right, they didn't work but the explanation, "official" or not has little to do with sloppy workers or "blue-eyed blondes" helping sabotage things.
A big part of the reason WAS money. The ammo makers get paid for for ammo that passes inspection which includes firing tests. If the ammo won't function in the "American" test gun with the long chamber they have made a lot of ammo that will be rejected and they won't be paid for. Too many rejected lots of ammo and the company might loose the contract. They might have shaded the tolerances to the long side or a larger shoulder so the ammo would function acceptably in the "american" gun which means it would give trouble in the British short chamber gun. There was also some dispute about greased ammunition or coating with hard wax. Both will improve the function of a "clean" gun but increase the stoppage rate in a dirty gun or dirty environment. Greased or wax coated ammo being basically dirt magnets. Wax being somewhat better than oil or grease.
I find much of the info to date misleading. Comparing energy of chemical (explosive) vs mechanical is pointless. The do not have the same affect on a target.
A .50 solid bullet can destroy a water cooled engine in 1 shot. A 20mm thin shelled round may explode on the engine's surface and essentially do nothing.
A .50 cal bullet can punch a .50 hole through Aluminum skin and do nothing, a 20mm thin walled shell can strip whole sheets of skin off a target aircraft when the aircraft is moving at high speed.
Many of the write ups to date are too simplistic.
There are several important categories that must be considered that a round needs to deal with, air vs water cooled engine, self sealing vs non sealed fuel tanks, small vs large aircraft (or lightweight vs robust). Also important are pilot or other armor, and round dispersion (based on distance to target and, gun positions and muzzle velocity/round drag).
In the Pacific 6x.50 cal in the wings was perfectly acceptable to shoot at non sealed fuel tanks and unarmored aircraft. Very few bullets and the plane was in flames
In the Europe 6x.50 cal in the wings also worked enough. And the P-47 damage reports with its 8 fifties were never questioned.
But 4x20mm the FW-190 and other aircraft used were also very effective. May of the Russian aircraft used 1 or 2, 20-23 mm centerline (or near to) in their fighters and found them to work on German aircraft.
Also many of the expert German pilots found the 1x 20mm center line to work well for them.
The .30 cal was universally scoffed at but in the beginning (BOB) 8 per aircraft was standard in England. They would use typically half there load to bring down 1 German but it worked.
Before a serious comparison can be made the conditions must be understood.
Shooting down a Zero vs B-17 are not the same in terms of gun needs. I have seen reports of many pilots taking down 3, 4, 5 even 7 Japanese aircraft in 1 battle. The best the Germans ever did was 2 B17's no matter what armament/airplane they used (in one battle).
When asking the question we must make sure the comparison is valid when the results are in.
A .50 solid bullet can destroy a water cooled engine in 1 shot. A 20mm thin shelled round may explode on the engine's surface and essentially do nothing.
A .50 cal bullet can punch a .50 hole through Aluminum skin and do nothing, a 20mm thin walled shell can strip whole sheets of skin off a target aircraft when the aircraft is moving at high speed.
Many of the write ups to date are too simplistic.
There are several important categories that must be considered that a round needs to deal with, air vs water cooled engine, self sealing vs non sealed fuel tanks, small vs large aircraft (or lightweight vs robust). Also important are pilot or other armor, and round dispersion (based on distance to target and, gun positions and muzzle velocity/round drag).
In the Pacific 6x.50 cal in the wings was perfectly acceptable to shoot at non sealed fuel tanks and unarmored aircraft. Very few bullets and the plane was in flames
In the Europe 6x.50 cal in the wings also worked enough. And the P-47 damage reports with its 8 fifties were never questioned.
But 4x20mm the FW-190 and other aircraft used were also very effective. May of the Russian aircraft used 1 or 2, 20-23 mm centerline (or near to) in their fighters and found them to work on German aircraft.
Also many of the expert German pilots found the 1x 20mm center line to work well for them.
The .30 cal was universally scoffed at but in the beginning (BOB) 8 per aircraft was standard in England. They would use typically half there load to bring down 1 German but it worked.
Before a serious comparison can be made the conditions must be understood.
Shooting down a Zero vs B-17 are not the same in terms of gun needs. I have seen reports of many pilots taking down 3, 4, 5 even 7 Japanese aircraft in 1 battle. The best the Germans ever did was 2 B17's no matter what armament/airplane they used (in one battle).
When asking the question we must make sure the comparison is valid when the results are in.
Not defending the .30 cal, but can't help but wonder, what % of load was typically used for .50 cal kills?
Njaco
The Pop-Tart Whisperer
I don't think he knows. That post is all he posts - check his other posts. They're all the same.
That is because the same argument is in many, many threads.
For the .50 depends on target.
And SBD with 2x.50 shot down 4 zeros in one fight.
A P-47 shot down 5 or 6 Germans in 1 fight.
A Red tail sunk a destroyer with 6 x.5.
The all had ammo left over.
Bob Johnson in his P-47 had a FW-190 run dry over 300x 8mm hits and he still made it back. A FW-190 can carry 1800 rounds (possible, not know if this was actually on the plane the time the attack took place)
A ME-109 shot down a P-51 with 1x20mm shot.
Of course for any plane it depends on surprise (less bullets), pilot experience (greater - less bullets), target ruggedness (fewer for a Zero than a B-17), speed, angle of attack, wind, gun location (wings, centerline etc)...
This is my point the past discussion are only about the gun and not everything else, and not supported with data just gun round specs.
For the .50 depends on target.
And SBD with 2x.50 shot down 4 zeros in one fight.
A P-47 shot down 5 or 6 Germans in 1 fight.
A Red tail sunk a destroyer with 6 x.5.
The all had ammo left over.
Bob Johnson in his P-47 had a FW-190 run dry over 300x 8mm hits and he still made it back. A FW-190 can carry 1800 rounds (possible, not know if this was actually on the plane the time the attack took place)
A ME-109 shot down a P-51 with 1x20mm shot.
Of course for any plane it depends on surprise (less bullets), pilot experience (greater - less bullets), target ruggedness (fewer for a Zero than a B-17), speed, angle of attack, wind, gun location (wings, centerline etc)...
This is my point the past discussion are only about the gun and not everything else, and not supported with data just gun round specs.
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Matt308
Glock Perfection
Well since you do not read PMs from moderators, I'll post it here for all to see. If you keep posting the same stuff verbatim, you are gone. You can have a consistent position, but cutting and pasting paragraphs of the same text over and over is not participation, but considered spamming. We look forward to your next posts that contain some diversity on content.
If it was sunk, then how were the Germans able scuttle it almost a year later?
The boat was not a Destroyer, but actually s Torpedo Boat. It was the T22, and was attacked by the "Red Tails" on 25 June 1944. It was put out of action but not sunk. The Germans ended scutteling it in Feb. 1945.
There are s lot of myths that are passed on as truth with the Red Tails. Do you also believe that they never lost a bomber?
I was hoping you would prove the claim. Alas, here are the Tuskegee airmen myths, the 'sunken destroyer' is one of them.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDQQFjAA&url=http%3A%2F%2Fwww.tuskegee.edu%2Fsites%2Fwww%2FUploads%2Ffiles%2FAbout%2520US%2FAirmen%2FNine_Myths_About_the_Tuskegee_Airmen.pdf&ei=3pFQUbaQEKW74AS4kICIBg&usg=AFQjCNGo_3keLwlZ45zyxyBg734eQh66_Q&sig2=noH8ayRRe3HLCvoYy9pSJQ&bvm=bv.44158598,d.bGE
Sinking 'several small boats' was indeed what a battery of HMGs was capable for, that again does not prove that a destroyer was ever sunk by them. The solid-nose B-25s were sinking the bigger ships with bombs, not HMGs.
The destroyer that was heavily damaged by the Tuskegee airmen was the ww1 warship, with displacement of 615 tons. The ww2 USN and IJN destroyers were displacing easily over 2000 tons.
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Point being it is another myth that it was "sunk". Just like never losing a bomber they were escorting. Unfortunately if you speak out against these myths, you are racist.
