Shortround6
Lieutenant General
And the cause was known and easily fixable. WHY is wasn't done is another question.
You might want to take your own advice.
20mm cannon, best, worst, specs, comparison to LMG, HMG etc.
- Thread starter claidemore
- Start date
And the cause was known and easily fixable. WHY is wasn't done is another question.
You might want to take your own advice.
Glider
Major
Yes the US 20mm guns in 1942 were unreliable (as was the ammunition a point often forgotten). But in 1942 the RAF were not unreliable and by 1945 the US had fixed the problems, the USN 20mm cannons were copies of the RAF (and therefore reliable) Hispano II and V.
True but its one more than you have posted, it shows the damage inflicted by four hits, damage that the 0.5 couldn't come close to inflicting, damage the Spitfire was lucky to get away with.
It shows that unless you hit a critical point eg pilot or engine then the 0.50 will just cause a few small holes, whereas the 20mm can and does cause very serious damage. Points you have not tried to deny.
For the USN there was
Actually I have. In the Med a number of USAAF units converted from the Spit IX to the P51B/C and one of the reasons they didn't want to lose the Spit was because of the reduced firepower. There were other reasons but this was one of them.
Wrong and Right. Wrong - other countries chose the 20mm for the same reason, increased firepower. Right - they did have different guns and ammo. The Russians had a better HMG with until 1943 better ammunition and went for the 20mm. The reason it changed in 1943 was that the US copied the Russian HMG ammo. The IJAF had the same gun as the USA and they also went for the 20mm.
Why ignore the explosive content of the different 20mm guns as they are very relevent to the discussion?
I also note that you have never tried to comment on the big outstanding question which drives a coach and horses through your case.
WHY WERE THE USN SO KEEN TO START USING THE 20MM IF THE 0.5 WAS AS GOOD?
I await your views on that question with some interest
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Ok name the explosive used, the difference between them, the shrapnel created and the affect on aircraft each had in WWII You need to answer that if you want to discuss it. I dont have it and I dont ever remember seeing it.
I can tell you studies of grenades showed they ended up in 2-3 big pieces and now grenades are made with wire or ball bearings for more destruction. I can tell you that AA missile warheads are pre-fragmented for the same reason. In WWII I don't know of anyone using enhancement techniques for 20mm ammo. So the German Minegeshoss is thin sheet metal and about all you get is a few small pieces of thin metal or over pressure.
I do know that .50 SAPI ignites fuel tanks ever some hits take out self sealing taken (not sure how many but some). I also know that ,50 CAL SAPI hitting any structure in an WWII aircraft causes damage probably most of the time based on angle and structural content WWII plane cant be heavy so they are essentially weak to structural damage. And no amount of quoting specs will tell you how badly mangled an engine, frame member, landing gear, prop, drive shaft etc is damaged by a .50 SAPI hit. And I do know the SAPI vs ball on a metal structure are totally different.
The number one reason for USN switch to the 20mm was range, with higher aircraft speed more range is needed. They did not push for 20mm in WWII the Oerikon version due to low velocity this was a specific requirement in WWII. They tried to upscale/modify other 20mm versions but never found something they really liked until the Colt. Take a look in the link I quote earlier it has that in their.
Another way to look at it was the .50 cal was fine until somewhere in the jet age. Th F-86 used them successfully but that was the limit.
How about providing such information for all .50 cal rounds, including SAPI?
Prove it - show some concrete evidence that .50 was as effective as 20mm at igniting fuel tanks.
It can also be proven that 20mm HE or SAPI hitting any structure causes a lot more damage, and can prove it. You have yet to provide a single shred of photographic evidence to back up your claims.
No mention of USN aircraft, such as the F7F, or F9F being armed with 20mm and other USN aircraft switching to 20mm prior to the jet age...
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Shortround6
Lieutenant General
Some of that information is available in Tony Williams books. Fillings often changes with availability though.
If you don't know what you are quoting or what the difference between hand grenades and 20mm shells are don't bother writing it down. WW I and WW II grenades that ended up in 2-3 big pieces and a lot of dust were cast iron.
NOBODY was making cast iron 20mm shells. If you suit the explosive to the shell body material and thickness and heat treat you CAN get decent fragmentation. Grenades are now made with wire and ball bearings both for more destruction at short range and less danger to the thrower. Those 2-3 large pieces could be lethal at several hundred yds range. Much further than the grenade could be thrown. Grenades use pre-notched wire coils or steel balls because it is a cheap way to get the desired results.
You can say it but that does not make it true, NOBODY was making cast iron AA missile warheads.
And once again you confuse German ammo with Hispano ammo. Hispano ammo used forged steel bodies with the HE cavity machined out. Much thicker shell walls than the German Minegeshoss shell. Larger, heavier fragments. Germans also had non-Minegeshoss shells and in fact that is what the MG/FF was introduced with. In fact of all the nations to use 20mm shells ONLY the Germans used the thin wall shell.
AA shells and Missile warheads need controlled fragmentation because they expected miss distances of several yards if not a few dozen yards. You need both an effective pattern and big enough fragments to do damage after they have traveled a short distance. Fragments tend to loose velocity very quickly.
I am glad that you KNOW this. Nobody else does. There was NO SAPI .50 cal ammo in WW II. You had M2 AP and M8 API. About the ONLY difference was 1 gram of incendiary material placed IN FRONT of the AP core. While I can certainly understand AP ammo acting differently on armor than ball I am not so sure about "metal structure" especially if it is aluminum. You do know that the ONLY difference between .50 cal M2 AP and .50 cal Ball is that the steel core in both (identical in size, shape and weight) is heat treated (hardened) in the AP round?
I don't have a penetration table for the M2 ball but the M1 ball( about 400fps less muzzle velocity and a about 20% less muzzle energy) could penetrate 1/4 in armor at 200yds. Or 6in of concrete. I don't imagine an aluminum flange, beam or tube standing up very well to that.
Do you even have any idea what you are talking about? The .50 cal WILL outrange the 20mm Hispano. The Bullets are more streamlined than the 20mm shells. Since they both start at the same speed it makes little difference over PRACTICAL WW II ranges like under 600-700yds. TO fire much further you need both a Gyro gun sight and some sort of range finder like the radar range finder in the upper lip of the F-86 intake.
I have NO idea what you are talking about with the "Oerikon version" as the US Navy NEVER used an Oerlikon gun in an aircraft in WW II or during the 40s or 50s. The ship's deck mounted 20mm Oerlikon guns shared little more than a name and basic operating principle with the Oerlikon guns used by the Germans and Japanese. The AA guns used some of the same shells (projectiles) as the Hispano gun but used a different shaped cartridge case. Muzzle velocity was actually very close.
For an idea of what a single 20mm Hispano round could try this video:
View: https://www.youtube.com/watch?v=-p8h43TRXwk
When even Four .50 cal WW II rounds can do that kind of damage get back to me.
Glider
Major
If you want to look at the damage a 20mm cannon can do have another look at that Spitfire, four hits in non critical areas and the plane is a write off. Without a warhead the 0.5 will do nothing, with a the small warhead carried in a 0.5in almost next to nothing. Four 0.5 hits in those areas would ahve done no damage at all.
This I agree with but the problem is that it has to HIT THE STRUCTURE a near miss is nothing
You can of course support this statement? I would to like to see it
I say this as range had nothing to do with it. The only F6-F5 Hellcats which were fitted with 20mm were the Nightfighters, and nightfighters fight at very close range compared to dayfighters.
So the question is why would they need more firepower at night at close range. The awnser is simple, at night if you don't get a first time kill then the bomber stands a good chance of getting away. The limited angle of the radar arc, the workload of the pilot having to monitor and track the now evading target and fly the plane made it almost impossible to get a second shot. To get the one shot kill you had to get the maximum firepower in the minimum time and that meant replacing two of the HMG's with 20mm cannon.
This is also supported by the Fighter Arcraft OCnference held in I think 1943 where the debated what made the ideal fighter. The issues of the 20mm vs 0.5 was debated at some length and the USN stated that (guess what) they wanted the 20mm as it did more damage in a shorter space of time than an aircraft with 0.5. The USN didn't mention range at all
It is also supported by the balistic charts for the P38 which showed that the 0.5 and 20mm had very similar ballistics and therefore range.
So over to you again.
Can you support your statement that the USN made the change as they wanted extra range from the 20mm?
View: https://www.youtube.com/watch?v=idfMaeAk9z4
WWII video on fighters, P-47 and P-51, mostly shooting FW-190 and ME-109s.
Note the length or fire is typical less than 1/2 sec , none more than a second. damage is wing sections coming off, planes burst into flames, major explosions, planes blow up, etc major damage, not a little .5" hole in the skin.
The announcer even mentions the SAPI ammo.
Depending on the 20mm of choice a plane may even have longer time to fire with 5.0s than 20mm setup. certainly anyone with the 60 or 90 rnd drum could not shoot as long.
So a.50 cal setup had around 25-30 seconds of ammo per gun. The 90 round 20mm had around 14 seconds depending on gun type. The .50 cal could shoot roughly 30 to 50 trigger pulls, the 20mm around 14 to 28. And since I do not see a difference in gun camera evidence of actual combat footage of a 20mm doing much shorter trigger pulls, then the .50 is at least it good a setup for the targets in mind.
So no I do not see an advantage to the 20mm setup in WWII against fighters.
So here is you pictorial evidence (at least 50 x times over) the announcer talk about the "non existent round", the damage on a AL, steel, magnesium or whatever broke the planes apart is shown.
So in a none existent book? cite something, then show somehow it made a difference.
Go read about the mingeshoss and why it was replaced. IT WAS CAST, why because it was cheap. When they wanted more explosive they had to go to and draw it, they could not cast that thin. Go ask any mech engineer casting is the cheapest form of metal forming.
The US NAVY wanted a longer range shell and a .50 could not foreseeable be enhanced. The 20mm was chosen and attempts to increase range took them until the Colt before they accepted the gun system.
Also a thin wall shell behaves like a thin wall shell when it fragments form. You have to pre-fragment it to get controlled dispersion and frag size and geometry.
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Ohh a 20mm and drum of water I can show that.
View: https://www.youtube.com/watch?v=yzzDaOfbPZA
Meaningless drivel but fun to watch.
And what damage does a 20mm do with near miss? Nothing that is why both weapons were automatic to get a bunch of rounds downrange.
In the day the M8 was called the SAPI for semi armor piercing Incendiary. The actual M8 nomenclature was Semi-armor-piercing high-explosive incendiary (SAPHEI), names changed as new rounds and type were created.
View: https://www.youtube.com/watch?v=yzzDaOfbPZA
Meaningless drivel but fun to watch.
And what damage does a 20mm do with near miss? Nothing that is why both weapons were automatic to get a bunch of rounds downrange.
In the day the M8 was called the SAPI for semi armor piercing Incendiary. The actual M8 nomenclature was Semi-armor-piercing high-explosive incendiary (SAPHEI), names changed as new rounds and type were created.
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Lots of wishful thinking here from someone who is seeing what he wants to see:
Length of fire typically 1/2 sec? That's how long some of the extracts show, but only because they are showing small glimpses of the entire footage. Most of the footage is taken at close range ~ 75-50 metres.
Parts flying off? Several jettisoned canopies, plus spectacular explosions of drop tanks/unprotected fuel tanks (Ju 52) or aircraft hitting the ground, having barely taken off or landed - and (oops) there's even footage of a Mosquito supposedly being shot up by a P-38
This is from someone who, in an earlier posting, maintained that Luftwaffe fighters targeting US bombers and P-47s couldn't shoot them down because of their 20mm cannon:
Prove that the statements about the .50 destroying armour plate, and engines with one shot and prove that 20mm cannot destroy engines or wreck armour plate. Show us some concrete evidence instead of just spouting opinion please.
Shortround6
Lieutenant General
I see, the "announcer" says.......Please find a Army manual or listing of .50cal ammuntion that lists SAPI ammo.
Quite true but then which guns in which air force are you comparing? The ONLY US fighters that used Drums were were the P-400s, some P-70s and few odd balls. The P-38 carried 150 rounds, the P-51 with 20mm cannon carried 125 rpg. P-61 carried 200rpg, The F6F carried 225rpg and F4Us when equipped with 20mm guns carried 231rpg. Not as long a firing time as the .50 but it doesn't seem that the US 20mm armed planes were that short changed. Some P-40s only carried about 15-16 seconds worth of ammo for their .50s. the A-36 carried 200rpg for the fuselage guns, 250rpg for the inboard wing guns and up to 350 rpg for the outboard wing guns. P-51Ds could carry carried 400 rounds inboard and 270 rounds for out board guns.
Comparing US .50 cal guns to foreign guns gets a lot harder. The 20MM MG/FF in a 109 weighed LESS than a .50 cal Browning as did the Japanese Navy type 99-1 cannon mounted in early Zeros.
Throw in the fact that while the .50 cal bullet is 1/3 to 1/2 the weight of a 20mm shell the weight of a complete round is actually closer. The most extreme example being that a .50 round is 69% of the weight of a German 20mm MG?FFM Mine round. Or for the weight of 60 said rounds ( not including drum) you get 87 rounds of .50 cal ammo (not including links). Weight of .50 cal round is 112 grams bullet is about 38.4%. weight of 20mm Hispano round is 257 grams, shell is 50.5%.
Great, now if you can GUARANTEE that fighter designed in 1942/43, built in 1944, takes 2-3 months from factory door to combat theater and several more weeks/months to fly first combat mission will see ONLY enemy fighters, or only fihgters you already know about, have at it.
Shortround6
Lieutenant General
I really like your comparison. Who said the 55 gallon drum in the video had anything in it? You are going to haul a drum to a remote location in Greenland and then blow it up with stuff still in it?
and try doing the math again, trusting youtube can lead to strange conclusions. Caption below the video says 48 gallons. caption IN the video says 60 liters which = 15.85 US gallons.
And why are they shooting a water filled drum? to make a more spectacular video, other wise you just get little holes in and little holes out.
Nice shot with the .50 cal though. But I suppose in your world a 20mm round (even a dud) would pass right through the liquid filled container? Bigger diameter projectile with more weight and much more energy won't split the drum even worse?
.
Quite true, now lets take it a step further. A .50 cal (without mounting, gun heaters etc) weighs 29 kg, A Hispano gun weighs 50 kg. For the weight of 4 Hispanos you get just under 7 .50 cal guns. the Hispanos fire 40 rounds a second. the 7 (rounded up) .50 cal guns fire 93 rounds per second. the four 20mm cannon fired 10.28kg of ammo per second (not including links) the 7 .50 cal guns fired 10.41kg worth of ammo (not including links) the 4 Hispanos put 5.2 kg of projectiles near the target, the 7 .50 cal guns put 4.0KG of projectiles near the target.
DO you have any proof of this??
Anybody who described the M8 round as a "Semi-armor-piercing high-explosive incendiary (SAPHEI) is a hack of the highest order.
That is the cross section of an M2 AP round.
The M2 ball is identical in cross section, core was not hardened.
The M8 put SOME incendiary material in the nose with the "point filler", Why this should degrade the armor penetration so the ammo is down graded to "semi-armor- piercing" is beyond me.
Since there was NO HE material in the projectile I can't imagine why some boob would label the ammunition as "high-explosive".
20mm rounds that were HEI or some combination had material that was HE and a different material that was incendiary, there really wasn't a material that was both although explosives with a high aluminium content might qualify.
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Glider
Major
Still waiting for any evidence that range was the requirement. You keep saying this but there is nothing to support it and all the evidence says that range had nothing to do with it.
You also keep ignoring the fact that the USN had a number of aircraft with 20mm guns before the colt, plus they were copies of the Hispano II and V which were proven and reliable.
The rest of your posting was as bad, so bad I almost gave it a like, in the same way that some films are so bad I somtimes like them.
Why can you not support your statements? You keep asking people to support their statements and they do. So its not unreasionable to ask you to support yours, is it?.
Jabberwocky
Tech Sergeant
RAF testing of .303, .30, .50 and 20 mm ammunition showed the 20 mm was MORE likely to result in catastrophic airframe damage and MORE likely to set a fuel tank on fire, even when protected by armour.
Standard RAF 20 mm ammunition was basic ball, HE, AP/I and SAP/I. Pure AP rounds were used only occasionally.
The Hispano AP/I and the SAP/I matched or bettered the AP performance of the US M2 (early war) and M8 (mid-to-late war) armour piercing rounds. The advantage was significant as soon as any yaw was introduced with the round, thanks to the higher mass of the 20 mm round.
20 mm HE ammunition performance in penetrating armour was about the same or slightly better than that of a .303 API round, but inferior to a .50 cal round. Generally it would go through about 9 mm of face hardened armour THEN explode.
Standard 20 mm ball ammunition had about two thirds of the penetration of a .50 cal AP round at zero degrees deflection, but increasingly made up the difference as angles of impact increased, being about equal at 30 degrees of impact.
You do realise that the Colt Mk 12 is just a 20 mm Hispano with an increased rate of fire and modifications for the USN's 20 x 110 mm ammunition (basically a longer version of the USAAF's 20 x 102 mm ammunition)?
All major airforces, including the USAAF, concluded in the late 1930s or early 1940s that 20 mm was the minimum preferable calibre for air to air cannon. RAF, Armée de l'Air, Luftwaffe, VVS, Regia Aeronautica, IJA, IJN and the USN all switched from LMG to 20 mm cannon during this period.
The USAAF wanted to switch to a larger calibre than .50 cal, but was frustrated by its own inability to do so. There were various projects to replace the M2 with a faster firing, higher velocity and higher calibre weapons, most of which were painfully unsuccessful.
Most favoured was a design based around the German MG151/15, rechambered for the .60 cal (15.2 x 117 mm) anti-tank rifle round, with a higher rate of fire. There were at least four different versions of this tried. There were also the various 20 mm projects, some .90 cal (22.9 mm) projects, a 23 mm project (rework of the Madsen cannon), and the various 37 mm guns.
A big part of the problem was the US was looking for a simultaneous increase in calibre, rate of fire and muzzle velocity. Thus, many of its projects were over ambitious and doomed to failure because of either gun weight, reliability or complexity/cost. Trying to fire 3500 fpm ammunition out of a gun supposed to be performing at 1000 rpm or more is a serious challenge. Some .50 and .60 lightweight rounds were supposed to hit 4400 fpm!
They eventually went with necking up to .60 cal cartridge to 20 mm to make the 20 x 102, which went on to arm the M61 Vulcan, a project which began in 1945.
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Found this, kind of eludes to more than parity.
fromhttp://http://www.absoluteastronomy.com/topics/Supermarine_Spitfire_variants
Talking about he Spitfire
As you ask me find a source and quote it.
As a matter of fact the P-26 peashooter had a .50 cal as they wanted to up arm it. Also the F2A Buffalo and P40 had wings designed to incorporate either the .30 or .50 cal. This type of construction (box mount with belt feed) essentially became standard. Got that from a Dr. Jan Roskam, look him up. The 20mm of the time would not fit those dimension so the designers were creating wings specifically for the Browning weapons. Wing mods or upgrades we needed later to add a 20mm, something from a planners perspective you don't do in wartime. So at least early on the ,50 was planned, the 20 no.
The Germans quickly switched to essentially only Mingeshoss, thins walled HE not sure what Russian used.
Not sure what why you are basing any comments on less than 5% of the ammo and gun type that caused fighter combat losses. What about the other 95%
You do realize the Navy did not accept the HS as is was unsuitable and spent over 15 years making changes to it and the ammo until it was.
So the .50 cal setup was sufficient for WWII! My point exactly thanks.
Are you mental shortroudn???
yours
I responded to your post besuase you ASKED. Don't bring it up it you don't like the answer.
The fact that the military was looking forward towards new weapons does not mean the old were insufficient for the times. I have yet to see any credit evidence that the US military, other than planning for the future, was in any way convinced the .50 was obsolete. If the delta was so much then why did they not change over all planes to 20mm? The industrial base could have been converted. Just like new plane (and vehicle) types came out and we increased 40mm and 5" gun production. It was not the same plants and tools but new ones. Yet we mass chose to produce .50cal instead. So why where is the evidence this was even considered in a positive light?
fromhttp://http://www.absoluteastronomy.com/topics/Supermarine_Spitfire_variants
Talking about he Spitfire
As you ask me find a source and quote it.
As a matter of fact the P-26 peashooter had a .50 cal as they wanted to up arm it. Also the F2A Buffalo and P40 had wings designed to incorporate either the .30 or .50 cal. This type of construction (box mount with belt feed) essentially became standard. Got that from a Dr. Jan Roskam, look him up. The 20mm of the time would not fit those dimension so the designers were creating wings specifically for the Browning weapons. Wing mods or upgrades we needed later to add a 20mm, something from a planners perspective you don't do in wartime. So at least early on the ,50 was planned, the 20 no.
The Germans quickly switched to essentially only Mingeshoss, thins walled HE not sure what Russian used.
Not sure what why you are basing any comments on less than 5% of the ammo and gun type that caused fighter combat losses. What about the other 95%
You do realize the Navy did not accept the HS as is was unsuitable and spent over 15 years making changes to it and the ammo until it was.
So the .50 cal setup was sufficient for WWII! My point exactly thanks.
I gave you a 16 page link... go read it.
Are you mental shortroudn???
yours
I responded to your post besuase you ASKED. Don't bring it up it you don't like the answer.
The fact that the military was looking forward towards new weapons does not mean the old were insufficient for the times. I have yet to see any credit evidence that the US military, other than planning for the future, was in any way convinced the .50 was obsolete. If the delta was so much then why did they not change over all planes to 20mm? The industrial base could have been converted. Just like new plane (and vehicle) types came out and we increased 40mm and 5" gun production. It was not the same plants and tools but new ones. Yet we mass chose to produce .50cal instead. So why where is the evidence this was even considered in a positive light?
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Keep it civil...
Both of you keep it civil!
Shortround6
Lieutenant General
No. I don't believe so.
Actually I like the answer just fine. Empty 55 gallon steel drum showing target effect vs a water filled 15.85 gallon plastic drum that NEEDS the water filling to create the hydraulic shock to split the barrel.
Not my problem if you don't understand the difference.
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