.50 cals on Spitfires

[michaelmaltby]

".... The sobering thought is that these men were so rare amongst the thousands of pilots flying in combat on all sides that we know many of their names today."

Very true. Killer instincts. Close and - preferably - in the back. Chivalry be damnxd. And no - such men are not psychopaths.

MM

 

[Edgar Brooks]

According to R.Dunn in his book "Exploding Fuel Tanks" the German bombers had an advanced high degree of protection for the fuel tanks. So much so that RAF pilots would aim for the engines/cockpits rather than pepper the wings. There are many stories and pictures of German bombers coming home or ditching looking like Swiss cheese..

RAF pilots didn't have time, with a closing speed above 100mph, to pick and choose what part of the enemy to aim at; if the sight came "on," they fired.

It is interesting to note that as the BoB was starting the RAF was still in the process of retro-fitting its fighters with ss materials and also to note that many of the Spitfires and Hurricanes left one tank unprotected in the fuselage. Production aircraft had full protection.

The Spitfire's top tank was never sealed, since there wasn't room for the material, and keep the (already inadequate) fuel load; eventually a fireproof bulkhead was fitted between the pilot and the tanks. Hurricane pilots deduced that their (worse) situation was due to the fire, in the wing tanks, being drawn into the cockpit through the open framework of the wings.

So IMO arming with .50cal would have greatly increased the RAF's ability to quickly bring down more bombers and less getting away with only damage

Unfortunately practicalities work against that idea; the Spitfire and Hurricane were designed around a battery of 8 x .303", and it would have been impossible to just swap the two guns. The .5" barrel was 18" longer than the .303", so some of that was likely to stick out in front of the Hurricane's wings, slowing it down even further. On the Spitfire, the outer pair of guns (where the leading edge tapered back) would have suffered the same problem. Then you have the longer ammunition of the .5", which would have needed new, wider ammunition "cans," with consequent deeper stagger between gun breeches, forcing guns rearward, into the area where the wings' cross-sections get thinner, causing possible bulges, and more drag.
The .5", without ammunition, was 32-45lbs heavier than the .303", so you're talking of putting an extra 64-90lbs (plus ammunition) strain on the outer portion of each of the Spitfire's wings. The .303" was also 350r.p.m. faster than the .5", so could put a greater number of rounds into the enemy, with a greater chance of hitting the pilot; inspectors were also finding that the German bombers were carrying ever thicker armour, which was becoming impervious to .303" .5" alike.

 

[Edgar Brooks]

The most ironic thing is that the british had a local 12,7mm design , the Vickers C, not particulary fast firing but belt feed, reliable and far lighter than the Browning.:

Development, for aircraft, ceased in 1928, because "not particularly fast firing" = 700rpm, against 800 for the Browning .5" 1150rpm for the .303". As for being "far lighter," it weighed 26 kilos = 57 lbs, against 55-68 for the .5" Browning, and 22.75lbs for the .303".

The Vicker C could be imbedded inside Spitfire wings without the bulge caused by the Hispano but in the end the Spitfire used all foreign designed weapons

Luckily this country has no time for that "Not Invented Here" nonsense.

 

[Shortround6]

We have been over this a number of times.

One of the really critical points is WHEN in 1940 the .50 gun went from a bit under 600rpm to about 800rpm cycle rate and WHAT was needed to make the change.

The older guns could be changed (both were called M2) unlike going from the 800rpm M2 gun to the 1200rpm M3 gun. The question is, was it a matter of adjustment and changing a few springs or was more involved? and when were the retro kits/parts available.

Second point is how much heavier a battery can the MK I Hurricane and MK I II Spitfire carry without affecting performance too much. Climb being much more affected by the increase in weight than speed. The .50 weighs 2.5-2.9times what a .303 Browning does and the ammo weighs about 5 times as much. Four .50 cal guns with 200rpg weigh about 150lbs more than eight .303s with 350rpg. Adjust for gun chargers, ammo boxes, mounts, gun heaters, etc.
Also remember that some British fighters were being refitted with constant speed props just weeks before the BoB, take off with the older two position props could be around 100yds longer. Adding even a few hundred pounds to these fighters could make a difference in performance. MK II Hurricanes and MK V Spits offer a much better opportunity for heavier armament. And the opportunity was taken up. Perhaps some .50 cal armed MK II Hurricanes could have been fielded near the end of BoB?

 

[Shortround6]

Development, for aircraft, ceased in 1928, because "not particularly fast firing" = 700rpm, against 800 for the Browning .5" 1150rpm for the .303". As for being "far lighter," it weighed 26 kilos = 57 lbs, against 55-68 for the .5" Browning, and 22.75lbs for the .303".

As noted above, the US .50 Browning didn't get to the 800rpm firing rate until 1940, which is all the more reason for the British to turn it down in the late 20s/early 30s. Another often (very often) ignored fact is that for the 20s and most of the 30s, the US .50 cal ammo had a MV closer to 2500fps than 2900fps. It was only upgraded in the very late 30s.

 

[TonyE]

I am not an aviation historian, my interest being in the weapons and particularly their ammunition.

Although mention has been made in this thread and on the linked Spitfire site of other potential armament options at the beginnning of the war, I have seen no details of one of the serious contenders, the 13.2mm Hotchkiss round and the FN manufactured Browning gun.

Britain had taken delivery of 35 Hotchkiss 13.2mm heavy machine guns in 1935 for trials for Land Service, and whilst the ammunition was satisfactory some aspects of the gun was considered unsuitable for British service. By 1938 attention had switched to the potential use of the same round, but in the FN built version of the Browning for Air Service. FN had the European licence for Browning designs and had developed the heavy MG in 13.2mm calibre to the point where it was some 5 kg. lighter than the American M2 and fired at a higher rate of 1050 rpm.

A great deal of work was done in the UK in the 1938-40 period to develop loads for the 13.2mm suitable for air use. These included solid steel AP rounds with a base cup of coppers and both nose fuzed and base fuzed HE and HE-T shells. There would be no problem with manufacture since Kynoch had been making 13.2mm ball, AP, tracer and incendiary ammunition since the late 1920s.

Ordnance Board Proceeding 3,268 dated 25.10.39 gave instructions for ground trials against Blenheim wings, engines and tanks from directly astern at 200 yards using the experimental cupped AP bullet shown in one of the drawings below. The request included "Will the Board arrange for fire-fighting apparatus to be available in case the petrol is ignited"

OB Proc. 5,998 dated 3.5.40 was a request for 13.2mm dummy cartridges to assist with the design of ammunition feed arrangements anf OB Proc. 6,795 reported on further trials with AP ammo. However, by the time of OB Proc. 8,732 dated 27.9.40, which examined Kynoch and FN produced ammunition it was stated "This report is printed for record, the development of 13.2mm ammunition for manufacture in this country for use in the 13.2mm Browning (Belgian) gun being no longer a requirement." The fall of Belgium and the capture of the FN plant at Liege may well have been the impetus for this decision.

Attached are some of the drawings I have of the ammunition.

Regards
TonyE

 

[Glider]

Very Interesting, thanks

 

[Airframes]

I agree, very interesting - thanks Tony. Sounds like it could have been a very useful and effective weapon, which I suppose didn't go further due to then current requirements in the field allied to known and 'in place' production tooling.

 

[stug3]

Problems with the Hispano 20mm cannon was mentioned in the other thread as being a contributing factor in the failure of the Spitfires to shoot down a greater number of aircraft. Going through Cooper's book I compiled the following statistics -

2 Mar 6a/c engaged 2a/c suffered cannon failure
15 Mar 19 '' 8 " " " "
2 May 28 " 10 " " "
20 Jun 37 " 12 " " "
28 Jun 14 " 3 " " "
30 Jun 31 " 19 " " "
6 Jul 30 " 12 " " "
7 Sep 33 " 3 " " "

So of 198 spitfire that engaged in aerial combat, 69 aircraft suffered one or both cannons failures. That's close to 35% of the attacking force, not ideal in anyones book I would imagine.

Was this an isolated phenomenon or a more common occurance? Did it happen anywhere else in the PTO, MTO or ETO?

 

[Jabberwocky]

Was this an isolated phenomenon or a more common occurance? Did it happen anywhere else in the PTO, MTO or ETO?

Uncommon, but not completely isolated. The RAF had problems with 20 mm gun heating on the Spitfire Mk V as well in the ETO, through 1941 and into 1942. They mostly solved it with reworked ducting, but eventually went with a thorough re-work in the later build Mk IX/VIII and onwards.

The problems for the RAAF were fivefold:

1. Poorly manufactured gun heating ducting (with some examples being delivered without gun heating tubes at all) and no suitable replacements, due to the limited manufacturing capabilities in Australia;
2. Extreemly high altitude combats, which the Hispano disliked because of the cold
3. Very dusty conditions, which the Hispano disliked. Typically stoppage rates doubled in very dusty conditions. The best solution was to make sure the gun ports were sealed with doped fabric.
4. Poor ammunition quality (I think the Australians used locally manufactured ammunition). Poor ammunition quality also affected the RAF in Malta, where they got a lot of stoppages from US manufactured ammunition.
5. Pooly manufactured belt feeds, which were manufactured in the UK. There were three different belt feed manufacturers for the Hispano II. Belt feeds typically accounted for 50% of Hispano stoppages. The RAAF Mk Vcs had the Austin Belt Feed Mechanism, which just happened to be the worst of the lot.

The RAAF reported stoppage rates as low a 1 per 180-200 rounds for their Hispanos over Darwin, improving to about 1 per 400 later in the year. At the same time the RAF was getting an average stoppage rate of about 1 per 1500 rounds for their Hispanos in Mk IXs in the ETO and only a little worst for their Mk VIIIs in the MTO. The RNZAF was getting stoppage rates of about 1 per 650 rounds with Beaufighters with the old drum feeds, which were less reliable than the belt feeds.

 

[stug3]

Belgian ground crew refuelling Supermarine Spitfire Mark XIVE, RM764 'MN-M', of No. 350 (Belgian) Squadron RAF at Lympne, Kent.

 

[Smokey Stover]

A lot of bob pilots had their guns synced in to just a few yards and all inboard to outboard were adjusted to converge at a single point in space so that the concentration of eight MG's all hitting the target in the same spot meant it would almost always knock a hole in just about anything. The .303 was small yes, but lets not get confused about how effective it was. Otherwise how do you account for all the aircraft RAF pilots shot down during the summer of 1940. Britain had two effective fighters with true and tested armaments. I imagine not to many people were eager to spend time and resources on trying to adapt every aircraft in service to take the 50 cal. It would have simply been non productive at a period in history were every second counted. Im my opinion i think the whole argument is rather irrelevant. The RAF did the job with the tools they had available and thats all that matters. Not to mention where exactly would all these 50 cal or any other calibre come from. And where were these guns and bullets have come from? I mean in 1940 the US had no desire to help Britain in it's fight against Germany. And im not hating in any way just saying. Britain had to make do with what it had and regardless of which gun was the best, when you are fighting for survival you will use whatever you can get your hands on at the time. I think too much is being attributed to this issue. Someone name me an aircraft gun that didnt suffer from the odd stoppage. The stats (if indeed correct) are negligible at best.

 

[MIflyer]

An article in the latest Flight Journal magazine says that the big push for .50 cal in the Spitfire came from the realization that a large percentage of the 2 TAF fighter bombers would be Spitfires, and they had a limited ability to carry any bomb load over any significant distance.

 

[Smokey Stover]

Im a little dubious of those links with all respect. There isnt even a reliable source for them. But i'll take your word for it, for now.
I posted a link a few minutes ago about the Spitfires apparent lack of range that one might find interesting. It certainly wasnt the short legged escort fighter a lot of people like to make out. And was tested with many modifications and extra fuel tanks that were produced for the P-51. Which until early 1944, didnt have the range itself to fly round trip to Germany and back. The problem with ww2 history and fact finding is it's now been so long it's hard to say for certain whats fact and whats fiction. Not that im saying things were made up, but memory fades and evidence gets lost or disappears. Plus the very nature of war and all the confusion, uncertainty, and propaganda means the waters are constantly muddied. History books are not always unbiased and objective. And witnesses (if indeed there are many left now) can be prone to memory loss and fabrication/misinterpretation. And not through fault of their own. It's just human nature, and as humans we are all susceptible to making mistakes.

 

[Greyman]

The debate about replacing the Spitfire's .303s with .50s persisted in the RAF for years -- until the Mk.IId Gyro Gunsight was officially adopted. The Hispano round's trajectory and time of flight was much more in sync with the .50 than the .303, and this was enough to overcome the benefits of the 4 x .303 armament.

 

[Shortround6]

I imagine not to many people were eager to spend time and resources on trying to adapt every aircraft in service to take the 50 cal. It would have simply been non productive at a period in history were every second counted. Im my opinion i think the whole argument is rather irrelevant. The RAF did the job with the tools they had available and thats all that matters. Not to mention where exactly would all these 50 cal or any other calibre come from. And where were these guns and bullets have come from? I mean in 1940 the US had no desire to help Britain in it's fight against Germany. And im not hating in any way just saying. Britain had to make do with what it had and regardless of which gun was the best, when you are fighting for survival you will use whatever you can get your hands on at the time.

We have been over the .50 cal gun issue in other threads. The .50cal gun and ammo of 1939-40 was not the .50cal gun and ammo or 1942 let alone 1943. The 1930-40 guns had lower rate of fire and a lower velocity bullet and apparently, no incendiary ammunition production which makes the superiority of a single .50 gun over a pair .303s a bit suspect at that point in time.

As for the bolded part. The US may not have been doing all the British might have desired but the US, in general, was far from having no desire to help.
The US was making plenty of aircraft for the British (the deal for Packard Merlins was signed in Sept of 1940) and plenty of other war materials were being shipped. True it was for cash at this time (mostly) but the US was sometimes taking a back seat in deliveries ( allowing France and Britain to get earlier delivery while US squadrons still flew biplanes or P-26 Peashooters.)
There were also drives in the US to take up collections of small arms, old helmets, binoculars to help equip the home guard after Dunkirk.

1941 might well have been different than 1940 but US did set up the "neutrality patrol" in 1939 and it was much expanded during 1940 and 1941.
By the Sept of 1941 the US was de facto providing escorts for convoys to Britain.
"USS Greer ineffectively engaged U-652 on September 4; and on September 11 President Roosevelt declared Axis ships entered the neutrality zone at their own risk, and ordered the U.S. Navy to attack any vessel threatening ships under American escort.[10] HX 150 sailed September 16, 1941, as the first convoy with American escort.[11] ON 18 sailed September 24 as the first westbound convoy with American escort.[12] The Gleaves-class destroyer Kearny was torpedoed while escorting Convoy SC 48 on October 17, 1941.[13] The destroyer Reuben James was torpedoed and sunk on October 31, 1941, while escorting Convoy HX 156 with a loss of 100 lives"

The loss of life of the Rueben James crew was small potatoes indeed to what the British were going through but the ever expanding aid to Britain started well before Pearl Harbor.

WHile lend lease wasn't signed until March of 1941 it was proposed in late 1940...................just saying.

 

[Smokey Stover]

We have been over the .50 cal gun issue in other threads. The .50cal gun and ammo of 1939-40 was not the .50cal gun and ammo or 1942 let alone 1943. The 1930-40 guns had lower rate of fire and a lower velocity bullet and apparently, no incendiary ammunition production which makes the superiority of a single .50 gun over a pair .303s a bit suspect at that point in time.

As for the bolded part. The US may not have been doing all the British might have desired but the US, in general, was far from having no desire to help.
The US was making plenty of aircraft for the British (the deal for Packard Merlins was signed in Sept of 1940) and plenty of other war materials were being shipped. True it was for cash at this time (mostly) but the US was sometimes taking a back seat in deliveries ( allowing France and Britain to get earlier delivery while US squadrons still flew biplanes or P-26 Peashooters.)
There were also drives in the US to take up collections of small arms, old helmets, binoculars to help equip the home guard after Dunkirk.

1941 might well have been different than 1940 but US did set up the "neutrality patrol" in 1939 and it was much expanded during 1940 and 1941.
By the Sept of 1941 the US was de facto providing escorts for convoys to Britain.
"USS Greer ineffectively engaged U-652 on September 4; and on September 11 President Roosevelt declared Axis ships entered the neutrality zone at their own risk, and ordered the U.S. Navy to attack any vessel threatening ships under American escort.[10] HX 150 sailed September 16, 1941, as the first convoy with American escort.[11] ON 18 sailed September 24 as the first westbound convoy with American escort.[12] The Gleaves-class destroyer Kearny was torpedoed while escorting Convoy SC 48 on October 17, 1941.[13] The destroyer Reuben James was torpedoed and sunk on October 31, 1941, while escorting Convoy HX 156 with a loss of 100 lives"

The loss of life of the Rueben James crew was small potatoes indeed to what the British were going through but the ever expanding aid to Britain started well before Pearl Harbor.

WHile lend lease wasn't signed until March of 1941 it was proposed in late 1940...................just saying.

Fair comment sir. Im not America bashing at all. Im simply saying British technology (especially aircraft) was just as effective as any other country at that time, if not more so. And i totally get Roosevelt was in a tricky position, on the one hand keeping the people happy who at that time were very anti war, and on the other hand recognising that Germany was a very real threat and must have known eventually the US would have to do something or risk being left behind in arms/defence. I just think some of the lend lease terms or deals were solely in the best interest of the US at the expense of the British empire. Which lets face it, while already in decline, the war just hastened its end. But for that i blame Churchill in part if not entirely. The man seemed obsessed with forcing the US into the war in europe by any means possible, when that time and energy could have been used for more pressing and serious matters.But thats another story...