.50 cals on Spitfires

[zajuts149]

The British used the .50 cal Brownings in addition to the HS 20mm cannons in later versions (e-wing IIRC).
I'm curious if anyone knows if the .50 cals were considered on earlier Spits, especially before there was a reliable 20mm cannon. I would think that a 4x.50cal battery would pack a significantly better punch than the 8x.303 that was used on the Spit I and II. Am I right? And does anyone know if this was considered/tested?`

 

[Colin1]

A large number of armament types were considered for the Spitfire from manufacturers such as Madsen and Browning, the .50cal was one of them. I forget the details but I will post them up when I get home tonight.

 

[NZTyphoon]

Just before Mitchell died he designed a Spitifre variant (Type 312) with 4 x 20mm Oerlikons mounted in the wings and a redesigned cooling system (Tony Buttler British Secret Projects: Fighters and Bombers 1935-1950 pages 35, 55.

The reason the .50 Browning wasn't used was because it was considered to be under-developed by the Air Ministry. More likely they wanted to continue with the .303 because of the millions of rounds of ammo in storage. To my mind it was a stupid decision At the time it was considered the .50 was already well developed: had British fighters been armed with (say) 4-6 .50s during the Battle of Britain they would have been a great deal more effective. And, considering the problems the British had getting the 20 mm Hispano working the .50 Browning would have been a good weapon to have.

 

[looney]

Is the .50 that much better than a .303? Sure the .50 is heavier but IIRC it didn't carry any explosives similar to the .303
The 20mm is the 1st round large enough to carry extra BOOM. Thus why bother with .50, and put all efford in placing 20mm.

The 20mm was considered by all (Allies and Axis) as the most effictive calibre for shooting down fighters.

 

[tail end charlie]

The British used the .50 cal Brownings in addition to the HS 20mm cannons in later versions (e-wing IIRC).
I'm curious if anyone knows if the .50 cals were considered on earlier Spits, especially before there was a reliable 20mm cannon. I would think that a 4x.50cal battery would pack a significantly better punch than the 8x.303 that was used on the Spit I and II. Am I right? And does anyone know if this was considered/tested?`

This site gives a lot of info on the subject

http://spitfiresite.com/2010/04/sorting-out-the-e-american-armament-for-the-spitfire-mk-ixxvi.html

 

[Colin1]

Is the .50 that much better than a .303? Sure the .50 is heavier but IIRC it didn't carry any explosives similar to the .303
The 20mm is the 1st round large enough to carry extra BOOM. Thus why bother with .50, and put all effort in placing 20mm.

The 20mm was considered by all (Allies and Axis) as the most effective calibre for shooting down fighters.

Before you open up this particular can of worms
I would read around, this debate is well documented elsewhere on the forum

.303 did not have the penetrating power of .50 and wouldn't crack open armour plating like the bigger round

You should also consider the relative merits of 'bigger' and 'big enough'; the .50cal didn't have any problems despatching Luftwaffe fighters in the battle over Germany with the added bonus that more .50cal could be carried per mission platform than 20mm.

 

[looney]

I know about the discussion. But b4 war (when the Spit was developped) 8x .303 was considered heavy armament. During the war it soon became obvious that the .303 was to light and they installed 20mm... Sure they had problems with the 20mm but 4x 0.50 was hardly better than the .303

I haven't been able to find my scource again but I once read that .50 armed fighters needed a lot more bullets to shoot down a enemy compared to a cannon armed fighter. And as such needed to be a lot longer on the enemies tail.
Late war most German fighters where put into service for bomber killing and where heavier (added gunpods, armor etc etc) and less manouvrable.

For a fighter I'd take a 20mm anytime over a .50. I think 4x .50 was weak, 6x was barely enough and 8x good.

IF you check this site (http://www.quarry.nildram.co.uk/WW2guneffect.htm see table 2) you will see that the gun effectiveness of the .303 and the .50 M2 are both 2.1

 

[Colin1]

(when the Spit was developed) 8x .303 was considered heavy armament. During the war it soon became obvious that the .303 was to light and they installed 20mm... Sure they had problems with the 20mm but 4x 0.50 was hardly better than the .303
The RAF's frontline fighters were upgraded with armour protection at least twice prior to WWII upon intelligence reports of the heavier German armament being fitted to the Bf109. It is curious that they didn't make the connection between armour and armour-defeating during the same period.

I haven't been able to find my scource again but I once read that .50 armed fighters needed a lot more bullets to shoot down a enemy compared to a cannon armed fighter. And as such needed to be a lot longer on the enemies tail.
Your source doesn't sound terribly scientific in its prognosis. There is little doubt that a cannon will hit you harder than a heavy machine gun but in the case of fighter vs fighter it is worth considering a sledgehammer vs nut analogy; why crack a nut with a 2lb sledgehammer when an 1lb sledgehammer is performing the same task adequately? Against yield per round you also must consider rate of fire, I don't recall any anecdotal material recording USAAF fighters running out of ammo trying to bring down a Luftwaffe interceptor (based on the assumption that his fire was effective ie he was hitting his target)

Late war most German fighters where put into service for bomber killing and were heavier (added gunpods, armor etc etc) and less maneouvrable.
Agreed

For a fighter I'd take a 20mm anytime over a .50. I think 4x .50 was weak, 6x was barely enough and 8x good.

Armament preference largely depends on mission profile. Your average Luftwaffe pilot in 1944 would likely agree with you. Your average USAAF pilot likely would not. I would also revise your armament load-out opinions to 4 x .50s as comfortably adequate, 6 x .50s as easily sufficient and 8 x .50s as more than adequate - all based on a typical USAAF mission profile for the late war period.

 

[tail end charlie]

Armament preference largely depends on mission profile. Your average Luftwaffe pilot in 1944 would likely agree with you. Your average USAAF pilot likely would not. I would also revise your armament load-out opinions to 4 x .50s as comfortably adequate, 6 x .50s as easily sufficient and 8 x .50s as more than adequate - all based on a typical USAAF mission profile for the late war period.

this site gives some added info

http://spitfiresite.com/2010/04/can...econd-world-war-aircraft-gun-controversy.html

 

[zajuts149]

This site gives a lot of info on the subject

http://spitfiresite.com/2010/04/sorting-out-the-e-american-armament-for-the-spitfire-mk-ixxvi.html

looks very interesting, and thanks to everyone else who replied. Didn't meant to rip up old 0.3 vs 0.5 vs 20mm war wounds..(ouch, that sounds painful)

 

[drgondog]

Is the .50 that much better than a .303? Sure the .50 is heavier but IIRC it didn't carry any explosives similar to the .303
The 20mm is the 1st round large enough to carry extra BOOM. Thus why bother with .50, and put all efford in placing 20mm.

The 20mm was considered by all (Allies and Axis) as the most effictive calibre for shooting down fighters.

The 8th AF Fighter Command experimented with HE .50 caliber rounds. I know the 355th FG tried them and IIRC the 56th also had a test sample.

My father's personal experience was that they were unsatisfactory and he recounted instances when the rounds exploded shortly after leaving the barrels. Once was enough for him. Henry Brown allegedly shot down two Fw 190s on Sept 27 with the HE rounds and apparently liked them. Having said this, Brown was an excellent shooter and possibly not be able to discern a particular advantage.

The USAF dedicated a lot of time and thought just before and during the Korean War on the .60 Cal (15mm) explosive round with the thought of retrofitting new bolt/barrel on all the installed M3s but in the end went to the 20mm for all future fighter armament (post F-89)

 

[zajuts149]

I agree that 20mm rounds is better over all, and history proves it. I wonder how A Spit Mk I or II would have performed with 4x .50cals vs 8x.303.cals vs bombers and fighters. The .50cal weighs almost 4x the .30 cal, so gun weight would double. but the volume of the .50 cal is not much more. The cartridge itself is 67% larger than the .30-06 that the US used(exactly, as it was just blown up in scale from the rifle round)

How many rounds did the Spit I carry per gun?
How much lead weight could be put by the 8x.303s in a typical burst(0,5 to 1 sec?)
What is the same number for 4x.50cals?
Late war spits carried 250 rds of .50cals. How do the weight of 4x.50cals w/250 rds compare to weight of 8x.303 with their ammo?
Would the extra weight(if any) hamper the Spit in a dogfight with the Bf-109E?
Would the heavier leadweight of the .50cal battery(if any) be more effective in bringing down the light/medium bombers of the day(BoB), the He-111, Do-17 and Ju-88?

I know the Armour Piercing qualities of the .50cal way surpasses the .303, but I'm curious on a more holistic level, on how the Spit would fare with another existing and working gun of the time, before the HS 20mm were up to snuff.

 

[zajuts149]

Just before Mitchell died he designed a Spitifre variant (Type 312) with 4 x 20mm Oerlikons mounted in the wings and a redesigned cooling system (Tony Buttler British Secret Projects: Fighters and Bombers 1935-1950 pages 35, 55.

The reason the .50 Browning wasn't used was because it was considered to be under-developed by the Air Ministry. More likely they wanted to continue with the .303 because of the millions of rounds of ammo in storage. To my mind it was a stupid decision At the time it was considered the .50 was already well developed: had British fighters been armed with (say) 4-6 .50s during the Battle of Britain they would have been a great deal more effective. And, considering the problems the British had getting the 20 mm Hispano working the .50 Browning would have been a good weapon to have.

I think so too. It's weird how defense ministries often think like grocery clerks when it comes to equipping their armed forces. I believe the German Army had the same thoughts when there was talk of introducing the MP-44 with the new 7.92x32mm round. They halted because they had 8 BILLION 7.92x57mm Mauser rounds on stock.

 

[Colin1]

Q: Would the heavier leadweight of the .50cal battery (if any) be more effective in bringing down the light/medium bombers of the day (BoB), the He111, Do17 and Ju88?

A: I know the armour-piercing qualities of the .50cal way surpasses the .303

...unless I'm mistaken

 

[buffnut453]

I think so too. It's weird how defense ministries often think like grocery clerks when it comes to equipping their armed forces. I believe the German Army had the same thoughts when there was talk of introducing the MP-44 with the new 7.92x32mm round. They halted because they had 8 BILLION 7.92x57mm Mauser rounds on stock.

I don't think interoperability is the peevish issue you seem to indicate. The standard .303 round was used in British Army rifles, the Bren Gun infantry support weapon, as well as in the RAF's fighter and bomber armament. Having just Fighter Command migrate to the .50 cal would necessitate an entirely new supply chain from factory to front-line for that one "customer" for both the weapon and the ammunition. Given the numbers of .303 rounds probably still lying around from WWI, the expense of retooling factories and the time constraints as Britain strove to prepare for the coming war, I think sticking with the .303 was the right choice.

 

[zajuts149]

I don't think interoperability is the peevish issue you seem to indicate. The standard .303 round was used in British Army rifles, the Bren Gun infantry support weapon, as well as in the RAF's fighter and bomber armament. Having just Fighter Command migrate to the .50 cal would necessitate an entirely new supply chain from factory to front-line for that one "customer" for both the weapon and the ammunition. Given the numbers of .303 rounds probably still lying around from WWI, the expense of retooling factories and the time constraints as Britain strove to prepare for the coming war, I think sticking with the .303 was the right choice.

It would not have made sense in the timeframe of may-oct 40. But would it have made sense to re-equip the entire RAF with .50cals from 1936 forward? It's common for armies to stick to their guns(literally in this case) That's why it was hard for the US to go to cannons from their .50 cals. There is always a certain amount of conservative thinking in defense ministries. I remember reading the requirements for an automatic rifle design made in 1910 by the War Office(or MoD?) in a book by Ian Hogg, and no wonder it took almost 50 years for the British Army to get one...

 

[Colin1]

...I will post them up when I get home tonight.

...as promised

The Spitfire Mk Ib
Fighter equipment of the RAF and the Luftwaffe during the Battle of Britain consisted of the Spitfire and Hurricane and the Bf109 and 110, the former witha battery of 8 x .303 machine guns and the latter with a mixture of machine guns and cannon. The weight of cannon fire was devastating when a direct hit was achieved and although the Air mInistry was aware that the British fighters' armament was effective an improved, and heavier type was needed for Luftwaffe aircraft were being equipped with heavier armour plate and this nullified the effect of the concentrated machine gun strikes. Fighter Command was not disappointed with the early results during the Battle and when offered the 20mm Hispano was only agreeable if 60rpg could be guaranteed in drums. A second proposal for 4 cannon with 150rpg or 6 x .50cal machine guns was also submitted.

In his original paper on the 8-gun fighter, Sqn Ldr Sorley had not overlooked the heavier calibre gun for he had written "The choice lay between the .303 gun, the .50 gun and a new 20mm cannon, which was of great attraction to the French and other continental countries. The .50 gun was newly developed and very heavy and was in fact a small cannon, the 20mm cannon was supersensitive to rigidity of mounting and was difficult to mount in aeroplane wings".

Progress had been made with the wing-mounted cannons as can be witnessed by Mitchell's submission of the Supermarine Type 305 with 4 Oerlikon cannons in the wings to Air Ministry Spec F37/35 in April 1936. Also Supermarine were always aware of the possibilities of the cannon as can be seen by Beverley Shenstone's report of the Paris Air Show in November 1936. Among other things he was looking for was examples of cannon-armed aircraft. Part of his report relates "One went to the exhibition hoping to see several types of cannon installation. Herein one was very disappointed. Where cannons were installed in French machines they were mock-ups, and very rough ones at that. The installations were crude in the extreme and one cannot think that they represented serious proposals. Wing installations seem to have died a natural death and the fuselage installation, either in or below, has taken its place. This change has, of course, been made possible by the use of twin-engined machines".

Prior to Shenstone's trip, a rep from Aero Engines Ltd visited Supermarine to discuss the problems associated with Hispano installation. He produced a drawing showing attachment points and other particulars. The weapon was entering service in France following trials with it mounted on the engine. No wing installation had been attempted. The maximum recoil force was 1100lbs and a 60-round cylindrical magazine had been developed. The four points used for engine mounting could be used, with adjustment, to mount the weapon in a wing.

The weapon had a travel of 20mm when fired with the magazine remaining stationary relative to the structure. It would also function on its side and the rate of fire, which could

 

[Colin1]

be preset, was between 520 and 720rpm. The rep left with a request for further information regarding the mounting.

Dowding himself was not impressed with the 20mm. On 26Jun38 he wrote to Sholto-Douglas saying he did not want 9 squadrons of Defiants. He also commented "There has been alot of talk about the efficiency of the 20mm cannon and I have seen no proof that this gun will give decisive results. We ought to have carried out the most careful experiments to prove its value before we adopt it. If this was not done I shall wake up in one year's time and be told I am committed to 15 squadrons of something with a 20mm cannon; whereas I can tell you now I do not want any and so perhaps save a large sum of money. I also want to be in the picture about the new single seat fighters".

Trials had taken place at Shoeburyness on obsolete airframes. Poor results were obtained with cannon shells exploding on contact with the skin with little effect to the internal structure. Dowding thought that if cannon were to be specified then he would rather have a larger gun with a heavier missile and slower rate of fire, whereby one direct hit would destroy the target. He said "Therefore we should start trials with a 37mm cannon" which was contrary to the thinking of Sorley and Buchanan, who favoured the eight gun fighter.

Following on from the Aero Engines Ltd visit, WM Hingston of the DTD arrived at Woolston with results of the Hispano cannon tests. It had functioned correctly in (a) the upright position, (b) raked up at 42degs from the vertical and (c) inverted. It failed on its side but it was felt it would perform with the magazine when supported in the rig at Boulton Paul.

Despite Dowding's objections, a letter arrived at Supermarine on 20Dec38 instructing Joe Smith to prepare a Spitfire for 2 x underwing Hispano cannon installations. Smith baulked at the idea and informed them by return that he was totally opposed to exposed cannon under the wings and that he could design an in-wing installation for 4 x cannons. He was informed that two would do for now.

Spitfire L1007 was fitted and without waiting for official approval was ready in early January. Unfortunately the embodiment loan of guns and ammo did not arrive until the end of March. The AUW of the cannon-armed Spitfire was 5,916lbs.

It was flown to Martlesham Heath along with cannon-armed Hurricane L1750 before moving on to AFDU at Northolt where the guns were found to be unreliable at low temps. It then went on to Drem for squadron trials and managed to shoot down a He111 at 20,000ft. It expended 41 rounds before the guns jammed. Moving on yet again to RAF Dishforth it was found that the ejector chutes were partially to blame for gun stoppages.

Dowding by now was beginning to warm to the cannon-armed fighter and Supermarine were awarded a contract for conversion of 30 Spitfires to take the cannon wing. The first of these reached 19 Sqn in June 1940 – R6261 – being followed by R6770 and R6776. On 01Jul40 the Air Ministry informed the CO of 19 Sqn that they were to convert to

 

[Colin1]

cannon-armed aircraft but when they arrived they only ever stayed for a few days at a time, being rapidly returned to 6 MU at Brize Norton for examinations.

Nor were they a great success, combat reports showed the frustrations of pilots who, having lined an enemy aircraft up, found that the guns jammed solid after a few rounds had been fired. The aeroelasticity of the wings made it twist slightly in tight manoeuvres causing the drum to come into contact with the skin and jam.

A stop gap appeared in the form of a mixed-armament Spitfire; P9504 still had four of its original Browning machine guns in the wings. It was found to be a great success and within five days of the trial, R6761, R6770, R6889, R6904 and R6919 were withdrawn from 19 Sqn service and modified. R6770 went to RAE Boscombe Down for modified spars as its guns were still jamming and R6904 went to Eastleigh for modification of its ejector chutes.


Alternative Guns
As long ago as July 1937 the Air Fighting Committee of the Air Ministry was considering a replacement of the .303 machine gun and issued a memo for an ultra high speed gun capable of firing 2,000rpm. The memo called for trials with eight of the guns firing explosive ammo and storage space for 4,800 rounds. Full scale trials took place on 14Dec37 with the Hungarian Gebauer gun and the effect was likened to 'a welder's torch held against a stressed skin aircraft'. The new gun was intended to replace the Brownings five years in the future.

Naturally there were problems, the rate of fire had an attendant barrel wear effect and increased weight. The suggestion was to drop the notion and concentrate on a gun with a higher muzzle velocity, which would provide an increased lethal range but the additional velocity entailed a larger powder charge and cartridge. A compromise in the shape of an armour-piercing .276 round was suggested.

The Air Ministry took out insurance by asking for designs of two new .303 machine guns in March 1938 as Browning replacements, the ultra high-speed and the high muzzle velocity.

The Madsen gun was also considered, the caliber being either 6.5, 8 or 11.35mm and rate of fire 1,000 and 1,200rpm, for this the recoil spring had to be reinforced. The gun was belt fed and the rounds held together by steel links. A 23mm Madsen was also considered and this too was belt fed with a rate of 400rpm. Hispano also produced a 23mm cannon while Vickers had their .50, a 24.5mm, a 37mm and 40mm cannon. The first had a rate of up to 650rpm, the second 100 and the last two 200.

Another new weapon to come to the Air Ministry's attention was the American Colt .50, examples of which arrived in the UK in June 1940. Drawings were ready the following month and trial installations commenced and by the following August Supermarine were proceeding with a trial installation of 6 x .50cal, plus a second installation of the same

 

[Colin1]

plus 2 x 20mm cannon. This was specified for the proposed Spitfire Mk III. Once the Hispano 20mm plus 4 x .303 had been accepted however, the Colt installation was put on a low priority on 09Dec40 until eventually being adopted several years later for the Spitfire Mk IX.