Why did almost all of the US fighters in WW2 carry machineguns, with the exception of the airacobra, Kingcobra & the F4UC. The rest carried 4,6 or 8 50cal 12.7mm machine guns.

Luftwaffe, Japanese, RAF & Soviet fighters generally carried a combination machinegun/cannon mount & some were purely cannon mounts.

Does anybody know why?

You forgot the P-38. Heh.

The USAAF was fighting a war against fighters. We had very very little bombers to shoot down. The .50 cal's I think are better suited in that way then 20MM due to its higher ROF, more weapons, more ammo, better chance of hitting.

We also had the P-61 had 4 20MM and 4 .50 cal.

quote:

Originally posted by Gibbage1:
You forgot the P-38. Heh.

The USAAF was fighting a war against fighters. We had very very little bombers to shoot down. The .50 cal's I think are better suited in that way then 20MM due to its higher ROF, more weapons, more ammo, better chance of hitting.

We also had the P-61 had 4 20MM and 4 .50 cal.

The P-61 was a bomber-killer, though, totally in agreement with your theory. Yeah, I think it makes alot of sense - it didn't take much to knock a fighter down, spraying 50 cals was probably an easier way to get a kill than placing a cannon round on your target.

Infrastructure and technological inertia had a lot to do with it as well, as did a lack of indigenous weapons to supplant the .50.

The .50 worked well, and was appropriate for the job: A to A gunnery against lightly armoured targets. If the USA had gone up against 4 engined heavies, I suspect it would of been replaced by something heavier. The USNs late war fixation with fitting cannon to its fighters probably has a lot to do with its desire to stop Kamikazes as effectively as possible.


Potential replacements were the .60 cal (15.25mm) very heavy machine gun (a high velocity redesign of the German MG 151/15 15mm) and the ANM2 20mm (A US copy of the Hispano). However, these never really got off the ground during the majority of the war, due to a variety of issues, some industrial, some institutional, some political. So there was no real alternative to the multiple .50 cal installation for US fighters. Through the war period various calibres (37mm, 23mm,

US fighters were moving towards banks of HMGs as standard armament while other nations (France, Britain, Germany, Russia, and Japan to a lesser extent) went to the single/ paired 20mm. Its just a different approach to the same problem given the external constraints; putting the most amount of high velocity lead and high explosive onto the target in the shortest amount of time.

Take a look at this article for a better explanation: http://www.quarry.nildram.co.uk/US404.htm

I'd say ISD's infrastructure has allot to do with it. If you start putting different guns in planes you have to re tool factories, retrain the workers, change supply chains, change shipping logistics, retrain all your pilots in how to use and fire the new gun, retrain all the ground crews in using and maintaining the guns, you have multiple stock piles of ammunition, guns and spare parts etc. It would have been a huge task to do this.

The US sticking mainly with the .50 in the European theatre meant all hit had to do was ship one type of ammunition in, supply one type of gun, spare parts for one gun only, train crews and pilots in one guns use and mainenance.

all the reasons above
european aircraft where bulit as interceptors too, while the american designs where too, just abit different, the european ones upgraded from mostly rifle calibre, to 20mm cannons, the americans never had a pressing need too.

think even the 190's started off with 4 mg guns or something fairly weedy

It is quite interesting why, the ME109E was cannon armed in 1939 & there was no serious bomber threat to the 3rd Reich at that stage

apart from the uk, france, russia

prewar thinking was that the bomber would always get through...

quote:

US fighters were moving towards banks of HMGs as standard armament while other nations (France, Britain, Germany, Russia, and Japan to a lesser extent) went to the single/ paired 20mm.

Actually the UK went for quad 20mm cannon, if you look at the flurry of mid-1930s specifications that were issued. So in 1937 there were quad cannon Hurricane and Spitfire designs around, as well as the Whirlwind and other aircraft. In the end the Spitfire went for, typically, only 2 20mm cannon, but almost everything else had 4.

quote:

It is quite interesting why, the ME109E was cannon armed in 1939 & there was no serious bomber threat to the 3rd Reich at that stage

It was still assumed that the 109E, as well as clearing paths for German medium bombers would have to defend the forward echelons of the Wehrmacht against other medium and light day bombers.

The reason is quite sipmle: there was no other gun in the US inventory to replace .50ANM2. The only heavier cannons were 37mm, but these were by far too heavy. The only real option was adopting 20mm cannon, but there was none such produced in US in early WW2. As the article linked in ImpStarDuece post says, US military in fact wanted 20mm and they bought licence for British Hispano. They wanted it badly enough to get blueprints and example cannons as early as january 1942! Unfortunately some idiot though he knows better than British and altered lenght of chamber. That created problems, which were not solved in time, to let "US Hispano" appear on planes which were entering MASS production in 1942/43. Later it was too late as industry inertia wouldnt permit a change. Not that US 20mm ANM2 was 'cured' entirely before WW2 ended... OTOH .50s were doing good vs. most of small planes. But that doesnt change fact, that 20mms would do better.

Before I get jumped by 'point-fifty' dedicated fans, I propose to check P-51 (without a letter) with 4 x British Hispanos: there are no bulges on the wings, i.e. Hispano was small enough to fit within P-51 wing. Also I suggest to calculate weights of armament sets, with assumption, a modest one, that single 20mm Hispano is as effective as 3 .50s.

P-51 B/C entered war with 4 x .50 with 1260 rounds total. That set weight was
4 x 39kg + 1260rds x 0,112kg = 156 + 141kg = 297 kg

Now lets replace above with two Hispanos, 50kg each. Further lets keep the weight of entire set unchanged, so
297kg - 2 x 50kg = 197kg

We are left with 197kg for ammo. One 20 x 110mm round weight is 0,240kg
197kg/0,240kg = 820/2 = 410rds

I.e. each Hispano would have 410rounds! No problem with practical realisation, since that weapon was belt fed, and there would be lots of space after one .50 gun and ammoboxes of both removal.

P-51B/C had enough .50ammo to fire for 350/13,3 = 26 seconds (although last 5s of that was fire from one pair only, as one of them had 280rds). And imaginary P-51B/C equipped with set of 2 x 20mm Hispanos would fire for 410/10 = 41 seconds! And that is with the same weight as RL plane!

Lets assume single .50 ANM2 effectiveness is 1, and single Hispano - 3:
4 x 1 = 4
2 x 3 = 6, i.e. P-51B/C armament of two 20mm Hispanos would be 1,5 times more effective that RL one with four .50s. Lets also have in mind, that ballistic properties of both weapons were similar - at least similar enough not to make difference within ranges of WW2 aerial shooting, i.e. not further than 300m.

Who would prefer to fly P-51B/C AND Mustang Mk.III with pair of Hispanos? I definately would!

That is of course for the sake of comparison, RL Mustang with Hispanos would probably get also a pair of .50s. Assuming that 21s of fire from all guns would be kept, it would be:
2 x 39kg + 2 x 280 x 0,112kg + 2 x 50kg + 2 x 210 x 0,240kg = 140 + 200 = 340kg

Only 43kg more than 4 x .50 set with:
2 x 1 + 2 x 3 = 8 / 4 = 2 - firepower twice greater than of RL P-51 B/C.

That would not create logistical problems, at least not greater than in case of P-38. All I can say is I wish 20mm cannons were used widely in primary US WW2 fighters

Kocur: Just to do a bit of what-if thinking on the Mustang with the 20mm cannons in the wings...while there were no bulges the cannons did stick significantly out of the wing (it looks mean that way ). What if they managed to fit some Hispano Mark V's in there...probably would cover all but a little bit of the barrel...imagine a Mustang with that sort of configuration.

...sort of like a Tempest I suppose

Ah, we can do even more what-if thinking What if replace Hispano with a 42kg 20mm cannon fed with rounds weighting only 0,205/0,183kg...

In fighter vs fighter action machine guns work fine.
During the BOB the 8 .303s in the Hurricanes and Spits did well.
The reason is you only need a small leak in a
fuel line, coolant, or oil to render the
enemy ineffective and most probably destroyed.
The .303 was obsolete before WWI, but 8 of them
did rather well in 1940.

The same holds true for 4-6 or 8 .50 cals.
The "Shotgun effect".
But for the .50 at least it would make a mess
of any hard object in a 1940's fighter.
No explosives, but an engine or wing spar hit
would spell instant disabelment and the loss
of the aircraft.
Even in a "self sealing" fuel tank a .50 hit
would cause a big hole and likely a fair sized leak.

In a piston fighter based air war the .50 was
a very potent weapon.
But later in Korea the .50 was to prove marginal
at best as jet's are a much harder kill.

Range, ammunition capacity and rate of fire
are the .50's advantage.
range is not well modeled in this game
and in Oleg's defence, I don't think that can
be accurately modeled without massive
amounts of extra calculations, code and a
dramatic slowing of your computers.
The bullets vanish when "spent".
In real life your bullets can kill for many miles.
I have seen accounts of people killed by
"spent" bullets/projectiles from above.

However I do feel that the .50 cals are severly under modeled
in this flight sim.

Sergio

one of the advantages is longer effective range, in theory anyways

quote:

Originally posted by p1ngu666:
one of the advantages is longer effective range, in theory anyways

Fighters rarely fire beyond 300 yards or so. Besides, the Hispano was just as good if not better ballistically than the M2. MG151/20 would be too if the Germans ever put ballistic caps on their fuses.

The rate of fire argument is false. MG151/20s fire just as rapidly as the M2. Furthermore, you don't see Dora or Spit pilots complain that they have trouble shooting down fighters.

The US didn't use cannon because it didn't have an alternative to the M2, pure and simple. It was unwilling to switch for a variety of reasons, not least being politics, economics, and the hassle.

quote:

Originally posted by Kocur_:

Before I get jumped by 'point-fifty' dedicated fans, I propose to check P-51 (without a letter) with 4 x British Hispanos: (

ITs called the A-36. A P-51 with an Allison engine and 4 20MM's. It was considered a ground pounder, not a fighter. The .50 cal had plenty enough firepower to shoot down other fighters, and the US had plenty of M2's and rounds but not Hispano's.

Also, you ever consider the SIZE of the 20MM shell? Or even the weight? The shell takes up about 5x the volume of the .50 cal! All 20MM's in early war only carried 60 rounds per gun! Later on even with belt feeding it only upped to 120 rounds. Compair that to 200-250 rounds of M2 per gun. That means the .50 cal has a lot more trigger time. When shooting at small dodging fighters, its important to have trigger time and more projectines with less gap between protectiles.

Also note the F4F. It started WWII with 4 .50 cal's in the -3 model. The -4 model added 2 more .50 cal's but lowered the number of rounds for each gun. Sounds like a nice trade right? More firepower, at the cost of less trigger time? Wrong. The pilots complained a LOT about it! They wanted the longer trigger time over the greater firepower since the 4x was working fine vs fighters!!! They switched BACK to the 4x loadout on the FM2 (-5 model made by Goodyear).

Every pilot that used the .50 cal in WWII will tell you it was MORE then adiquate for taking down enemy fighters. It was not till Korea when fighting much heavily more armored jets that the .50 cal finally needed to be replaced with something more potent.

quote:

Originally posted by Gibbage1:

quote:

Originally posted by Kocur_:

Before I get jumped by 'point-fifty' dedicated fans, I propose to check P-51 (without a letter) with 4 x British Hispanos: (

ITs called the A-36. A P-51 with an Allison engine and 4 20MM's. It was considered a ground pounder, not a fighter.

A-36A (NA-97) was not armed with 20mm cannons - had six .50, four in wings, two on engine sides. Im surprised to read you saying such a thing. The only 20mm Mustang was P-51 (NA-91) - 93 of them were deliverd to RAF, where served as Mustang Mk.IA, remaining 54 entered US service modified by installing two K-24 cameras, with designation changed to F-6A.

quote:

Also, you ever consider the SIZE of the 20MM shell? Or even the weight? The shell takes up about 5x the volume of the .50 cal! All 20MM's in early war only carried 60 rounds per gun! Later on even with belt feeding it only upped to 120 rounds. Compair that to 200-250 rounds of M2 per gun. That means the .50 cal has a lot more trigger time. When shooting at small dodging fighters, its important to have trigger time and more projectines with less gap between protectiles.

You get a bit confused when it comes to technical issues, dont you I cant tell anything about volumes of both rounds, but the terrible, King Kong weight of 20mm round was...about twice of .50BMG. You could have noticed in my post, that I did deal with ammo weights...
60rds was capacity of drum magazine - used before British developed their own belt mech for Hispano. 120rds is what Spitfire had, later planes, designed with Hispano in mind had 200rds.
Trigger time? Please read what I wrote above: Mustang with pair of Hispanos would have 41 seconds of 'trigger time' with set of gun+ammo weight equal to those of 4 x .50. That is considerably MORE than Mustangs had.

quote:

Also note the F4F. It started WWII with 4 .50 cal's in the -3 model. The -4 model added 2 more .50 cal's but lowered the number of rounds for each gun. Sounds like a nice trade right? More firepower, at the cost of less trigger time? Wrong. The pilots complained a LOT about it! They wanted the longer trigger time over the greater firepower since the 4x was working fine vs fighters!!! They switched BACK to the 4x loadout on the FM2 (-5 model made by Goodyear).

Rgrt. Try to note on your side, that there was difference in toughness of Japanese and European planes. You might also note opinion of Bearcat armament of 4 x .50 given by pilots from 1944 Joint Fighter Conference - were they pleased? Did they think it was suffcient and adequate? No really, in fact the only drawback of Beracat they noticed was weak armament.

Like I said: multiple .50s were good armament against WW2 fighets. Still however 20mm cannons were better.

quote:

Originally posted by Gibbage1:

quote:

Originally posted by Kocur_:

Before I get jumped by 'point-fifty' dedicated fans, I propose to check P-51 (without a letter) with 4 x British Hispanos: (

ITs called the A-36. A P-51 with an Allison engine and 4 20MM's. It was considered a ground pounder, not a fighter. The .50 cal had plenty enough firepower to shoot down other fighters, and the US had plenty of M2's and rounds but not Hispano's.

Also, you ever consider the SIZE of the 20MM shell? Or even the weight? The shell takes up about 5x the volume of the .50 cal! All 20MM's in early war only carried 60 rounds per gun! Later on even with belt feeding it only upped to 120 rounds. Compair that to 200-250 rounds of M2 per gun. That means the .50 cal has a lot more trigger time. When shooting at small dodging fighters, its important to have trigger time and more projectines with less gap between protectiles.

Also note the F4F. It started WWII with 4 .50 cal's in the -3 model. The -4 model added 2 more .50 cal's but lowered the number of rounds for each gun. Sounds like a nice trade right? More firepower, at the cost of less trigger time? Wrong. The pilots complained a LOT about it! They wanted the longer trigger time over the greater firepower since the 4x was working fine vs fighters!!! They switched BACK to the 4x loadout on the FM2 (-5 model made by Goodyear).

Every pilot that used the .50 cal in WWII will tell you it was MORE then adiquate for taking down enemy fighters. It was not till Korea when fighting much heavily more armored jets that the .50 cal finally needed to be replaced with something more potent.

FM2 Wildcat was built by General Motors.
GOTCHA!

Sergio

The A-36A Apache never had 4 Hispanos The A-36 had 6 .50 calibres, two in the nose and four in the wings. The 2 nose guns were often taken out on service machines though.

The only 4 Hispano Mustang was the Mustang Mk. IA, contractually designated P-51 under Lend Lease. They were based off the NA-91 design and 151 were made, 57 of which were retained for USAAF use.

The confusion usually arises because both the P-51 and the A-36A were known as the 'Apache' at various points in thier history. Throughout 1941 and into 1942 the USAAF officially refered to the P-51/Mustang I/IA as the 'Apache'. However, when deliveries to the RAF and USAAF began in 1942, the official name was swapped to the British moniker 'Mustang'. The NA-97 design, later designated the A-36A, then took up the 'Apache' name. In 1943 there was some effort to relable the A-36A with the name 'Invader' but it seems that both were eventually dumped for the more popular 'Mustang'.

quote:

Originally posted by Gibbage1:

Also, you ever consider the SIZE of the 20MM shell? Or even the weight? The shell takes up about 5x the volume of the .50 cal! All 20MM's in early war only carried 60 rounds per gun! Later on even with belt feeding it only upped to 120 rounds. Compair that to 200-250 rounds of M2 per gun. That means the .50 cal has a lot more trigger time. When shooting at small dodging fighters, its important to have trigger time and more projectines with less gap between protectiles.

5 times the volume? I think you'd better check your figures Gibbage

Dimensions for the .50 cal round were 12.7x99

Dimensions for the 20mm Hispano round were 20mmx110

Weight for the .50cal round was 112 grams

Weight for the 20mm Hispano round was 257 grams.

As for ammunition carried for Hispano armed fighters:


Spit Vb carried 60 rpg
Spit Vc carried 120 rpg
Spit IXe/XVIe/XIVe carried 140 rpg
Spit 21 carried 175 rpg inboard and 150 rpg outboard.
Hurricane IIc carried 91 rpg
Typhoon carried 140 rpg
Tempest V carried 150-175 rpg, with possibly 200 rpg with Mk V Hispano


FW 190As carried 250 20mm rpg inboard and 125 rpg outboard

FW 190Ds carried 200 20mm rpg

P-38 carried 150 rpg