Question !

[fffreeze220]

Why was the US the only country that used "normal" MG bullets on their planes allmost the hole war ?
Every other country was using cannons.
Can any 1 give me a good reason or have a good source to post.
thx

[brady]

They tryed the Hispano but The US felt it was generaly more bother than it was worh, It jamed a lot, so it was not untill late in the war when planes like the Helldiver(a serious pos) and the C hog came to be, but in the later case not to many were made.Even the 20MM's on the P 61 were often left off or prone to jaming.

  They also were intrenched becuase of the Massproduction aspect of it all, they wored well and were available in large numbers, it was felt changing the horse in mid stream would slow up the works.

 We wone the war by attration more than by having better weapons, look at the Sherman for example a seriously inferiour tank compare the the Panther, but they were reliable(mostly) and available in large quanties.

[K98k]

Maybe if enemy bombers were over American skies we'd opt for a heavier round as a matter of routine to knock'em down.  but thats just a guess

[dtango]

Fire in the Sky has a nice account of the differences of theory between the combatants.

Essentially the US were more in favor of using .50's vs. cannons because:

(1) Individually a heavy machine gun has a greater rate of fire than a cannon therefore you can put more bullets in the air.  This is magnified by the number of guns - e.g. 6 .50's vs. 2 cannons.  The belief was the % of getting hits were higher with more lead in the air.

(2) .50 rounds were lighter than cannon rounds therefore you could carry more ammunition.

(3) It was felt .50 cal armor piercing rounds though lacking explosive firepower made it for it by being able to penetrate deeper and hitting vital a/c components via penetration.

There's the flip-side argument for the above and it's an age old debate but that sums up the US theory I think.

Tango, XO
412th FS Braunco Mustangs

[Wotan]

lw cannon werent a result for the need to shoot down bombers. The lw developed its cannon well before the hvy bombers were over germany. This includes the 30mm and it was designed to be used against fighters as well as bombers.

The Brits tested extensively the 50 cal before the war and decided to stay with the .303s. The 303 and 50s both had a flat trajectory and could put out a alot bullets. The 303s could put out more. The brits prior to the war were worried about "bombers" yet from their tests figured the 303 would be adequate. And they were against pre war bombers. Against pre war aircraft the diference between 50s and 303s was just the size of the "whole". You could carry more 303s then 50s and their rof was awesome.

It wasnt until pilot armor and modern bombers that the 303s lacked.

The US planes were bigger and could carry from 6 to 8 hvy mgs. With the flat trajectory and rof they figured they could get more rounds on target. But if you look at weight of the 50s on a jug for instance it could take 3 30mms.

The US choice of 50 cals had nothing with range. Range was
irrelevant because effective kill range was figured up to 500m.

That mean hits beyond their were unlikely.

Read these AGW threads

http://agw.warbirdsiii.com/bbs/showthread.php?s=&threadid=14500

http://agw.warbirdsiii.com/bbs/showthread.php?s=&threadid=13544

Heres a link to Tony's article

http://www.quarry.nildram.co.uk/WW2guneffect.htm

Heres another

http://www.quarry.nildram.co.uk/ideal.htm

Cannons were more effective against fighters and bombers alike.

[brady]

Realy If you look at the 50cal and look at the Japanese modifacations to it you can clearly see the 50cals shortcomings. It was heavy and it's ammo was heavy, very heaver for an aircraft gun. The Ho 103 fires a 12.7mm round but it is considerably lighter both in terms of the round and the weapon, but very effective withen the common range at wich aircraft were normaly engaed at, also the Ho-5 20mm Cannon basicaly an up sised Ho 103(which is an improved 50cal) is still lighter. Lighter aircraft weapons like the MG 131 boasted higher ROF's than the US 50 cal but had shorter efective ranges, but this was not a factor realy since they were still deamed efective withen the expected range at which combat took place. Realy the US 50cal was not an ideal Aircraft weapon, although it was effective.

              Ho-103 and 50cal round pic I took at the Oregon Militay Museum:

[Innominate]

IIRC(If I'm wrong, someone correct me)  The US didn't just use "plain" .50 rounds.  US aircraft carried 50 cal API, a penetrator with a bit of incendiary material on it, to get things to start burning.

[F4UDOA]

There is one other factor as to why the US opted for .50 cal as compared to heavier cannon.

By the time the US entered the war against Germany the Luftwaffe was largely fighting a defensive war and they were not using the heavy buffs that were being sent to Berlin. The use of 30mil cannon by the Germans was because of the B-24, B-17, Lanc etc. Had the US been faced with a heavy bomber threat you probably would have seen a heavier caliber gun sooner. In the battle against nme fighters the .50 cal was probably the best weapon for the job. Extremely reliable, high rate of fire and more than enough power for the job. Obviously the Japanese fighter and bomber force never put the heavy fighter or bomber force to dictate a larger caliber weapon either.

However it should be noted that by mid 1945 the USN was completely commited to the 20Mill. The AAF did not make that commitment until the mid 50's.

[Wotan]

The 30mm cannon was developed before the allies had hvy bombers over germany. It was developed as an anti fighter as well.

The brits during the pre war years werent worried much about fighters when then chose the 303s. The were worried about bombers. The fact the us had 50s and other nations developed cannons has nothing to do with bombers.

The 50 was not the best weapon. Thats why I posted those links as all your points are accounted for in Tony Williams' conclusions.

I will refer you to this thread.

http://agw.warbirdsiii.com/bbs/showthread.php?s=&threadid=13544

[funkedup]

Get the "Report of the Joint Fighter Conference".  Pyro posted a quote from that way back.  The guys for the USN and USAAF who made the decisions about .50 cal vs. 20 mm actually have a debate on the merits of the different weapons in the report.  It's straight from the horse's mouth.

To summarize it, basically they felt that for the average pilot, rate of fire and flat trajectory were worth more than sheer hitting power, because these are the two most important factors in determining hit percentage.  Reliability and ease of installation figured into it also, but it boiled down to rate of fire and ballistics.

[GRUNHERZ]

I think its pretty clear that cannon were widely considered better overall by the end of the war, come 1945 there was only one service that thought they had any future usefulness in fighter combat.

[BenDover]

It thought they used .50 cals was because there were plenty of them left?

[davidpt40]

In a high-g dogfight, a pilot needs a weapon that has lots of ammo and has a high velocity and high rate of fire.  This is where the 50cal prevails.

Early 20mm cannons were crap.  They jammed, had low rate of fire, and small ammo loads.

[BenDover]

Originally posted by davidpt40
In a high-g dogfight, a pilot needs a weapon that has lots of ammo and has a high velocity and high rate of fire.  This is where the 50cal prevails.

guess he's never heard of the p51s jamming probs under high Gs?

[Nefarious]

Originally posted by BenDover
guess he's never heard of the p51s jamming probs under high Gs?

The 50 cals on the P-51 B were mounted on the guns edge I beleive, causing the jam under high G. This problem was corrected in the D model.