# Bf-109s and FW190s against B17s



## Cpt. John (May 15, 2017)

Hello guys, do you know wich models of BF109s (F-1, F-2, F-3... )and focke Wulf (A1,A4...) were used in europe in 1942-43 against B17s ?


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## tomo pauk (May 15, 2017)

Looking here:
_"The First Official Mission of the 8th Air Force, Mission Number 1, using their own planes, Boeing B-17 Flying Fortresses, did not occur until *August 17, 1942* when they attacked Rouen / Sotteville marshalling yard in France with 12 aircraft. All returned safely."
_
we can surely discount the Bf 109F-2 and earlier, and probably Fw 190A-2 and earlier. Leaves us with Bf 109F-4 and subsequent fighter models, plus of course the Fw 190A-3 and subsequent fighter models.


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## stona (May 15, 2017)

In August-December 1942 the Luftwaffe was flying predominantly Fw 190 A-3s and A-4s. There don't seem to have been many units still operating Bf 109 Fs, most were flying Gs, the G-2 had been introduced in May. The G-4 was just about appearing at this time.
Cheers
Steve


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## Cpt. John (May 15, 2017)

Thank you Guys


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## stona (May 15, 2017)

Into 1943 and the ubiquitous Bf 109 G-6 appears, deliveries to units in NW Europe followed those to units in the MTO, commencing in March/April. The next major variant (G-14) didn't appear until mid 1944, so you can ignore it.

Production of the Fw 190 A-3 continued into June 1943. Production of the A-4 continued (at least at Ago) until August 1943, overlapping the A-5 which was produced until August 1943 (at Marienburg). The A-6 started production in mid 1943 and continued well into 1944. All these dash numbers would have opposed the US bombing offensive as they became available. When a new version became available the older ones didn't disappear overnight !
The A-7 didn't enter production until November/December 1943, so that might be a bit of a stretch.

Cheers

Steve

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## Cpt. John (May 16, 2017)

Thank you


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## Koopernic (May 16, 2017)

Note Fw 190s and Me 109G could be modified or retrofitted in many ways. Me 109 often carried a pair of 20mm gondola guns under the wing. Fw 190 had a more adäquate firepower to begin with and though they also could carry gun packs are well known for being up armored where the pilot was fully encased in steal armor, had bullet proof glass for his side windows plus additional armor on vulnerable points such as engine and ammunition. These Stormbok or assault 190s were highly effective. They could resist return fire from the American bombers long enough to down them. The 190 would be damaged or the pilot might need to bail out but at least a 4 engined bomber and its crew of 10 were shot down and captured. These versions often were given 30mm MK 108 guns in the outer wing area. Only 3 hits were capable on average of bringing down a heavy bomber. These fighters were to heavy to fight the escorts and needed escorts themselves.


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## Greyman (May 17, 2017)

Koopernic said:


> These Stormbok or assault 190s ...



I was reminded of these when reading Jeffrey Quill's report after his stint of operational time during the Battle of Britain.

-------------------------------------------------------------------------------------
_
The existing armament is good for the destruction of enemy single-seaters, but it is rapidly becoming obsolete for use against bomber formations. Enemy bombers are now heavily armoured in the rear, and it appears that the rear machines of their bomber formations are firing cannon aft; the armament of eight .303 guns is therefore insufficient, both in range and penetrating power, for effective attack in the face of the rear armour and cross-fire encountered in these formations. It is apparent that our fighters must be split into two categories._

_Dog-fighters, for high altitude encounters with enemy escort fighters._
_'Destroyers' for the splitting up and destruction of enemy bomber formations._
_For the Dog-fighters, a high rate of fire and good 'spread' is required for the snap shooting at short range which is the usual order in these engagements, and for this the existing .303 armament is satisfactory.

For the 'Destroyer', however, heavy projectiles with great penetrating power which can be fired from long range are essential, and I consider that an armament of four Hispano Cannons is the absolute minimum to make it worth while putting a fighter into range of the fire which may now be expected to issue from the rear of the enemy's mass formations.

It will be a mistaken policy to try and compromise between these two distinct armament requirements. The question of weight is of great importance - the 'dog-fighters' must be kept as light as possible, as climb at high altitude, turning circle and general manoeuvrability are of great importance; therefore no extra weight must be added on account of unnecessarily heavy armament.

The 'Destroyer', on the other hand, will not be required to operate at high altitude and high rate of climb or great manoeuvrability will not be an operational necessity. Therefore considerable extra weight and wing loading can be permitted in the interests of range and striking power and forward protective armour.

The two differently armed fighters would operate in close co-operation, the 'Dog-fighters' forming a protective escort to the Destroyers.

J,K Quill
29 Aug 1940_

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## stona (May 17, 2017)

The compromise was never made between the two, mainly because the German bomber as a target disappeared from British skies. Two cannon and various combinations of machine guns or four cannon became the standards on British S/E fighters and roles were never divided


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## pbehn (May 17, 2017)

On 29 Aug 1940 the Spitfire had already been fitted with 2 x 20mm cannon, the Typhoon which was due to replace it had first flown 6 months before. Maybe Quill was under the impression that cannons would never work when fitted in wings because the Spitfire had problems. He seems to be proposing Beaufighters escorted by Spitfires. As far as I have read EVERY BoB pilot that had been hit by cannon and survived wanted them to replace their "pea shooters"


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## stona (May 18, 2017)

pbehn said:


> On 29 Aug 1940 the Spitfire had already been fitted with 2 x 20mm cannon



Earlier in fact. As early as 24th July 1940 Dowding wrote to Sinclair about the cannon armament, but expressing some reservations.

_"The present situation is that the guns of about six Spitfires in No. 19 Squadron are working satisfactorily, and the defects in the others will probably be rectified in about a week or ten days. 
I quite realise that information concerning the fighting qualities of the cannon Spitfire is required as early as possible, and I will take the first opportunity of getting it into action; but I am not at all keen on sending it up against German fighters since it will be extremely badly equipped for that task. I say that the cannon Spitfire is badly equipped to meet German fighters because it has only two guns and even the Me 109 has two cannon and two machine guns. Furthermore, it has fired off all its ammunition in five seconds."_

Dowding's reservations about engaging fighters are reflected in Quill's writing and the very reasons that the British went for the eight gun fighter in the first place.
I can't agree that the pilots were happy to swop their eight machine guns for two cannon either, at least whilst reliability issues persisted. In fact No. 19 Squadron, following a series of engagements in late August in which some or all their cannon had malfunctioned were keen for the exact opposite. Squadron Leader R Pinkham wrote.

_"In all engagements so far occurring it is considered that had the unit been equipped with 8-gun fighters it would have inflicted far more severe losses on the enemy. It is most strongly urged that until the stoppages at present experienced have been eliminated this squadron should be re-equipped with Browning gun Spitfires."_

He went on to suggest a swop with the 8-gun fighters from an OTU, and this is exactly what happened on 4th September. The aircraft from the OTU (at Haywarden) had seen better days, but the squadron diarist summed up the feelings of his squadron when he wrote.

_"First day with the eight-gun machines, and what wrecks. At least the guns will fire."_

It took a while for a successful installation to be developed for the Spitfire, and then in combination with four machine guns (later two .50 calibre machine guns or even four cannon). By then the large formations of Luftwaffe bombers had disappeared from British skies in daylight. The British did have a cannon armed fighter in 1940 in the Whirlwind, but its problems are well known and it could barely reach the bombers and would certainly needed protection from other fighters at the altitudes at which combat was taking place in August/September 1940. By 1941 it, and possibly the Beaufighter, would have had to contend with the Bf 109 F and then, later, the Fw 190, which I suspect would not have gone well.

Cheers

Steve

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## pbehn (May 18, 2017)

Oh I know all about the problems Stona, but the pilots obviously wanted canon that worked. There was a documentary on the BoB with an ex veteran (Wellum I think) and he had a German canon round compared to a .303 RAF round in his hand, the difference was huge.


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## stona (May 18, 2017)

They certainly wanted cannon to knock down the bombers, just as Luftwaffe pilots would later. By the time they got them most of the bombers had gone, at least by day.
Quill made the point that the bombers were becoming better armed and armoured and that rifle calibre machine guns were becoming less effective. The issue that Dowding was taking up (apart from the small ammunition supply) was the relatively low rate of fire of two cannon compared with eight machine guns. The eight gun fighter had been adopted to enable a short burst of fire, at a high rate, to deliver enough weight and hits to shoot down a target in a fleeting engagement of two or three seconds. As Salmond wrote in 1933, when he was AOC-in-C of ADGB: 
_
"the design of the home defence fighter and the tactics employed should be such as to produce the maximum fire effect in the minimum time."_

Dowding feared that the chances of scoring any hits in such a short fighter to fighter engagement with just two cannon were negligible. Both the existing Whirlwind and planned Typhoon carried four cannon. Ralph Sorley is often credited as the 'father' of the eight gun fighter, but this is a bit of a stretch, and one encouraged by Sorley himself. In 1931 an A&AEE report concluded that a six gun fighter was equivalent to two general purpose fighters (two guns). Later in 1931, at Dowding's behest, air firing trials proved the concept behind the multi-gun fighter. The trials showed that

_"the multi-gun type of fixed gun single-seater is more likely than the two-gun single-seater fighter, to produce the density of fire necessary to ensure a hit on a vital part of a target aircraft, in a time which approaches the actual average time during which aerial targets present themselves in air fighting."
_
Good reads on this subject are the Air Historical Branch 'Narrative on Armament, Vol II: Guns, Gunsights, Ammunition and Pyrotechnics' and GF Wallace's 'Guns of the Royal Air Force 1939-1945'. The latter is an old one (1970s), but still a good one..

Cheers

Steve

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## Shortround6 (May 18, 2017)

stona said:


> . The British did have a cannon armed fighter in 1940 in the Whirlwind, but its problems are well known and it could barely reach the bombers and would certainly needed protection from other fighters at the altitudes at which combat was taking place in August/September 1940. By 1941 it, and possibly the Beaufighter, would have had to contend with the Bf 109 F and then, later, the Fw 190, which I suspect would not have gone well.
> 
> Cheers
> 
> Steve



Actually the 10th production Whirlwind was not delivered to 263 Squadron until October of 1940. There weren't enough Whirlwinds during August/early Sept (6th delivered Aug 31st) for anybody to figure out what they could or could not do in combat. While fighter combat was taking place at altitudes which the Whirlwind would have great difficulty the bombers were not flying that high, especially when carrying bombs. 

It was the large increase in power that allowed the later fighters to carry the 20mm guns and do away with the two types of fighter idea. 

At 20,000ft an early model MK VB Spit could climb 59% faster (2440fpm vs 1535fpm) than a prototype MK 1 with two cannon and four machine guns.


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## stona (May 18, 2017)

Shortround6 said:


> Actually the 10th production Whirlwind was not delivered to 263 Squadron until October of 1940. There weren't enough Whirlwinds during August/early Sept (6th delivered Aug 31st) for anybody to figure out what they could or could not do in combat. While fighter combat was taking place at altitudes which the Whirlwind would have great difficulty the bombers were not flying that high, especially when carrying bombs.
> .



Well they certainly knew it couldn't take on the Luftwaffe's fighters at altitude.

By September Fighter Command was tasking squadrons to 30,000ft (above the Whirlwind's ceiling, never mind operational limits) on occasion. Al Deere recalled how uncomfortable that could be when patrolling over Dover at 33,000ft on August 28th.

_"We were hanging on our airscrews. It was cold, extremely cold; my feet like lumps of ice and tiny prickles of cold stabbed at my legs, just above the knees."_

Several others remember these high altitude escapades and they are recorded in the ORBs of those concerned. More often patrols were around 20,000ft and many interceptions seem to have taken place between about 16,000ft and 23,000 ft. Given that the Whirlwind's performance, to quote Sqn. Ldr. Eeles _"..above 20,000ft falls off quite rapidly" _and that _"above 25,000ft its fighting qualities are very poor"_ it was hardly the solution to the cannon problem. As Dowding noted on 27th October 1940, it was _"quite wrong to introduce at the present time a fighter whose effective ceiling is 25,000 ft." _He of all people should have known at what altitudes Fighter Command's fighters were required to operate.

Cheers

Steve


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## Shortround6 (May 18, 2017)

The thing is the Hurricane falls somewhere between. Which is one reason the Hurricane got the Merlin XX engines 
The MK I could barely beat 500fpm at 30,000ft and 500fpm was considered the threshold for formation (small formations) flight. 
1000fpm climb was thought to be the minimum for combat. Granted the Whirlwind was thousands of feet below even the Hurricane but the Hurricane I could not do (on paper) what was wanted or match the Spitfire. 

And if they _accepted_ the poor performing _bomber destroyer_ idea the Whirlwind might have worked had it been available in numbers. 
Kind of like I said earlier, with the coming of the Merlin XX and 45 the single engine fighters could carry cannon with adequate performance and the idea of using low performance heavily armed bomber destroyers was left to the Germans.

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## stona (May 18, 2017)

Yep, there are several accounts of squadrons of Spitfires and Hurricanes taking off together, the Hurricanes being left behind in the wake and exhaust of the Spitfires.
It was a fundamental flaw in the Big Wing theory espoused by Bader, Leigh Mallory et alter. Three Hurricane squadrons were based at Duxford and two Spitfire squadrons at Fowlmere. Bader admitted in interviews with Albert Price that in order to stay with the Hurricanes the Spitfires had to throttle back. Spitfire squadrons operating on their own had no such limitation. By definition the wing could not climb as fast as a squadron, seconds lost in gaining an advantageous altitude could, and did, result in missed interceptions. It even contradicted the first of Bader's own three rules of air fighting, "He who has the height controls the battle." Missed interceptions was something the Duxford wing excelled at. From 7th September to 29th October Bader led 37 wing operations which made 7 interceptions. The average interception rate for squadrons in 11 Group was over 50%. Operations on 1,2,5,7,8,10,11,13,15,17,19,25 and 29 October resulted in zero interceptions for the Duxford wing for the entire month.
Cheers
Steve

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## Ascent (May 18, 2017)

To me this does bring up an interesting question, how would the British fighters of 1943 handle a formation of B17's?

Plenty of cannon armed fighters around, did they have the punch to take them down?


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## Shortround6 (May 18, 2017)

Ascent said:


> To me this does bring up an interesting question, how would the British fighters of 1943 handle a formation of B17's?
> 
> Plenty of cannon armed fighters around, did they have the punch to take them down?




Well, it kind of gets back to the German use of Bf 109s and the "Gunboats" (five gun fighters). 
With the under wing gun pods the 109 stood a much better chance of taking down the B-17 although still not what was wanted and yet, according to many accounts, still needed normal 109s (3 gun fighters) to keep the escorts busy. The gun pods didn't hurt speed much but impacted climb, roll response, and turning. 
The Typhoon might _not _ be what was wanted for fighter vs fighter at 20,000ft and above but how well it would have worked against B-17 formations flying at 180-200mph? British _could _have fitted Spitfires with four 20mm guns and accepted the loss of performance against fighters for better anti-bomber work?

The 20mm Hispano was _roughly _equal to the German MG151/20 with each have a few pluses and minuses so the British fighters would have been better equipped than a 5 gun 109 and roughly equal to a 190 with four MG 151/20s. (not counting 7.92 cowl guns).

Perhaps the four Hispano guns were not ideal but between what the Germans actually had and what they wanted?


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## stona (May 18, 2017)

Plenty of Bf 109s with two heavy machine guns and a 20mm cannon shot down B-17s. Plenty of Fw 190s with two cannon and two heavy machine guns did the same. I don't see why a British fighter with four 20mm cannon, or two 20mm cannon and two heavy machine guns couldn't do the same. Of course the Germans were always looking for heavier and longer range anti-bomber armaments, but the basic package could be very effective in the hands of a decent pilot.
Cheers
Steve


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## Shortround6 (May 18, 2017)

BTW I would note that unless you get into rather ridiculous guns like MK103s or 50mm cannon the fighters cannot out-range the .50 guns on the B-17s.


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## pbehn (May 18, 2017)

stona said:


> Bader admitted in interviews with Albert Price that in order to stay with the Hurricanes the Spitfires had to throttle back. Spitfire squadrons operating on their own had no such limitation. By definition the wing could not climb as fast as a squadron, seconds lost in gaining an advantageous altitude could, and did, result in missed interceptions.



From what I read the problem was a little more complex. The maximum rate of climb of the spitfire and hurricane was at much different forward speed due to the completely different wings. It wasnt just a case of the Spitfires having to throttle back the hurricanes also had to climb at a reduced angle for them all to stay in the same piece of sky. The result was that spitfires and hurricanes together climbed slower than hurricanes on their own.

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## GregP (May 18, 2017)

So, what exactly is the question in the poll above and what is an Fw 109?

Are you asking which one we'd rather fly? Which one was probably more effective? Which one we liked best? I don't want to answer until I know what you asked!

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## BiffF15 (May 18, 2017)

Assuming he is asking which you would want to go hunting B-17's in, I would go with a Fw-190D-13. My reasoning is based on the assumption I will encounter a "few" of those pesky P-51's, P-47's, or P-38's that roam Germany. I believe it only has 3 guns (20mm). While it might be considered "under gunned" compared to a Mustang/Thunderbolt/Lightning it's performance would be more useful getting to, into, and out of the bomber formations.

Cheers,
Biff


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## Clayton Magnet (May 19, 2017)

3 centrally mounted MG151/20's on a D13 would not be undergunned against any American fighter sporting 6 or 8 M2's. 
That is almost an ideal armament arangment for the time, in my opinion. Whether it be a Fw190d13, or Yak3P with the 3 B20 cannons in the nose


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## stona (May 19, 2017)

BiffF15 said:


> Assuming he is asking which you would want to go hunting B-17's in, I would go with a Fw-190D-13.



I think one of the 'Doras' would be a smart choice, my back up would still be an A-8, but without the 337.3 extra Kg of armour, as fitted to the R2. 
Otherwise an Me 262 might be a good idea, but it would be a toss up whether the Americans or your own aircraft got you 
Cheers
Steve


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## Koopernic (May 19, 2017)

Clayton Magnet said:


> 3 centrally mounted MG151/20's on a D13 would not be undergunned against any American fighter sporting 6 or 8 M2's.
> That is almost an ideal armament arangment for the time, in my opinion. Whether it be a Fw190d13, or Yak3P with the 3 B20 cannons in the nose



Latter Fw 190D13 were to be equipped with the Jumo 213EB (replacing the Jumo 213F). This aircraft was a monster expected to do 488mph at high altitude and over 400 at sea level. The Forsyth book also notes that the Luftwaffe was already experimenting with the MG213 revolver breach canon on the Fw 190. Somewhat surprisingly they could be synchronized with the propellor as the revolving breaches locked before shooting.

The removal of the outer guns meant Fuel tanks were planed to be fitters there, particularly the ground attack versions which would have received toss bombing sights.

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## stona (May 19, 2017)

We are getting into Nazi paper planes again. As of April 7th 1945 just two D-13s are known to have been at operational units. We can let Biff have one of them, but really they are as irrelevant as the Ta 152 and other late war aircraft that were produced in minimal numbers.
Cheers
Steve

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## Shortround6 (May 19, 2017)

Original question was what was better against the B-17 and B-24. Yes you have to survive the escorts but the difference between 488 mph and 400 mph is going to be minimal against 180-200 mph bombers. Whatever you gain in less exposure time to defensive guns you loose in less firing time and aiming time for attacking. And with less firepower additional firing passes are needed.


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## Cpt. John (May 19, 2017)

Thanks guys


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## eagledad (May 19, 2017)

Cpt John

Aberdeen Proving Ground did a post war analysis of which fighter was most effective against the B-17/B-24 based on German combat films.

Please see

http://www.germanluftwaffe.com/archiv/Dokumente/ABC/a/Alliierte/US Air Combat Records WW II.pdf

Eagledad

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## drgondog (May 20, 2017)

BiffF15 said:


> Assuming he is asking which you would want to go hunting B-17's in, I would go with a Fw-190D-13. My reasoning is based on the assumption I will encounter a "few" of those pesky P-51's, P-47's, or P-38's that roam Germany. I believe it only has 3 guns (20mm). While it might be considered "under gunned" compared to a Mustang/Thunderbolt/Lightning it's performance would be more useful getting to, into, and out of the bomber formations.
> 
> Cheers,
> Biff


Biff - notably 3x20mm is far more balanced and effective than every Bf 109 in standard fighter mode. The 30mm was unquestionably the most powerful over 20mm but ballistics forced more closure to the B-17/24. As far as under gunned, no way 3xMG151/20mm are less effective than 6x or 8x 50 Cal.


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## Greyman (May 20, 2017)

eagledad said:


> Aberdeen Proving Ground did a post war analysis of which fighter was most effective against the B-17/B-24 based on German combat films.



Fascinating document.

Interesting to see how much better the 190 is than the 109 in taking on bombers. Although I wonder how much of the disparity was due to the Sturmböcke 190s ...


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## stona (May 21, 2017)

Greyman said:


> Interesting to see how much better the 190 is than the 109 in taking on bombers. Although I wonder how much of the disparity was due to the Sturmböcke 190s ...



And Luftwaffe tactics.

Cheers

Steve


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## BiffF15 (May 21, 2017)

drgondog said:


> Biff - notably 3x20mm is far more balanced and effective than every Bf 109 in standard fighter mode. The 30mm was unquestionably the most powerful over 20mm but ballistics forced more closure to the B-17/24. As far as under gunned, no way 3xMG151/20mm are less effective than 6x or 8x 50 Cal.



I'm actually of the same thoughts regarding numbers & calibers per the Fw-190D-13. I was alluding to previous conversations / debates about the quality of 6-8 x 50 cal's versus the less numerous, heavier 20mm but firing at a slower rate.

Cheers,
Biff


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## stona (May 21, 2017)

I believe it was the USN that came up with the formula that from a gun “horsepower” standpoint, one 20 mm cannon was equivalent to three .50-caliber machine guns.
Cheers
Steve


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## Shortround6 (May 21, 2017)

the 20mm vs .50 ca; was pretty much the Hispano vs .50. They had some of the same strengths and weaknesses. Against the MG 151/20 things _may _change a bit. The .50 being longer ranged (shorter time of flight) for one thing. Another is that figuring by arbitrary measurements (Muzzle horsepower?) the MG 151/20 and the .50 cal are closer together. Actual target effect may differ considerably.


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## drgondog (May 22, 2017)

BiffF15 said:


> I'm actually of the same thoughts regarding numbers & calibers per the Fw-190D-13. I was alluding to previous conversations / debates about the quality of 6-8 x 50 cal's versus the less numerous, heavier 20mm but firing at a slower rate.
> 
> Cheers,
> Biff


Biff - the Mg 151/20 had a rate of fire about 750rpm - 25% faster than the M2 50 Cal. The FW 190 versions with 4x20 plus two MG/151 15mm were even more devastating. When the Poll changes from "FW 109" I will cast the correct vote.

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## Shortround6 (May 22, 2017)

Bill, I believe the M2 _aircraft _.50 cal was firing at 750-850 rpm by the time the B-17s and B-24s were flying over Europe. Sources differ and the 850 may be on the high side but 750-800 seems to be widely reported for wing guns. During the 30s and through most of 1940 they did fire at 600rpm or less (much less if synchronized). The ground guns stayed at 600rpm or less until modern times.
I believe the change in rate of fire could be achieved by changing just a few parts, including the buffer? and could be done at squadron level. 
The 20mm big advantage was of course the HE ammunition. However the ammo belts were seldom 100% HE.
Luftwaffe belts (as with everything else) varied with time and place but were generally 1 : 1, 3 : 1, or 2 : 1 of HEI (mine), HE/T and APHE. 

The Muzzle horsepower rating is a bit bogus although perhaps useful for comparing a gun design. The 20mm Hispano had about 3 times the muzzle energy of the .50 cal and taking the muzzle energy times the rate of fire and converting it to HP gives the Hispano (at 600rpm) somewhere around a 2.2 advantage over the .50 (at 780rpm) (depends on exact loads/ barrel length and rate of fire) and doesn't count explosive charge.

Of course power at the muzzle is hard to translate into target effect at "long" (even 300yds or more) range. And trying to figure out the target effect of the HE and incendiary payloads can lead to long and bitter arguments.

The US .50 went through a major ammunition change just before the war, then saw the introduction of the M8 API round in late1943/early 44 which almost totally displaced the early mixed belts of AP, incendiary and tracer (2 : 2 : 1 ratio although the tracer fell out of favor) by the time the FW 190D-9 and later really show up in numbers the US is using small quantities of the M23 incendiary round. Much higher velocity and a major increase in incendiary payload although penetration is lousy. This is the major round used in Korea.

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## drgondog (May 22, 2017)

Shortround - I agree with everything you just posted with one caveat. I have read a lot of squadron reports that touch on armorer comments that the initial rate of fire for the 50's was 650+. I bow to your superior knowledge with respect to the buffer spring adjustment with another note that 355th armorers reduced jamming occurrences by reducing the buffer spring load - but no comment regarding ROF difference estimates.

As an aside, listening to a conversation between Henry Brown and dad - the subject of explosive round test was touched on with the follow on comment that the two were glad it didn't continue because of pre-detonation happenings not far out of the barrel. Neither are around fro me to pursue this, but I have searched far and wide with no success to identify the round or the program.

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## Shortround6 (May 22, 2017)

I will bow to your operational knowledge. Most books do not mention the feed problems that a lot of US .50 installations had or what was done to solve them, except that mention is often made of using electric motors from B-26 turrets to help fix the feed problems on the P-51B & C. 

The "explosive" round mentioned by your father and Henry Brown could well be the M23 incendiary, it did have a lot of problems with prematures and went in and out of production several times between WW II and Korea and manufacture was shifted from plant to plant at least once if not twice in attempts to solve the problem. I don't know if the problems were completely solved by Korea or just reduced enough for service use in a shooting war. I believe there were a few occurrences of the bullets igniting_ in the barrel._ 
A standard M8API has 15 grains (0.97grams) of incendiary compound in the tip ahead of the AP core. The M23 had 90 grains (5.83 grams) and was essentially a gilding metal covered steel tube full of incendiary material. It was around 500fpm faster in velocity than standard .50 cal ammo due to the bullet being so much lighter. about 10 grams lighter. 

There _may _have been a explosive bullet, I have never heard of it but there are a lot of things I have not heard of  
The M23 existed at the time I think you are referring to, it did have major problems in use similar to what I think you are describing. 
What the men in the squadrons called a particular round vs what the official nomenclature was may well differ. 

somewhere in the number of .50 cal threads on this sight I believe I posted a set of cross sections of .50 cal bullets including the M23.

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## stona (May 22, 2017)

Monroe's comments from Patuxent in full:

_"As it is now, we have the 50-cal gun which has reached its peak. The only improvements will be minor. The only good increase is to increase the number of guns. So it seems to be just about the right time to look for a better weapon. There are two possibilities here- the one we have and the one we might get shortly. The one we have is a 20mm gun. I think very highly of it. It is a fact, we have one here, and it is one in hand. It won't do what the 60 will do, but we haven't got the 60, and we won't have it for a year. So we are gradually working into all our aircraft the 20mm gun. To give you some idea of the 50 versus the 20 and dispel a lot of the ideas that have bothered us, I would like to give you a comparison. When somebody goes from four 50s to two 20s, to the layman that means a decrease in fire power. Actually, quite the reverse is true. In the horsepower of the gun, one 20 is equal to three 50 calibers. In the actual rate of fire delivered at the target, one 20 equals three 50s; in kinetic energy at 500 yards, one 20 equals two and one half 50s.
That adds up to four 20s equalling twelve 50 calibres, judged by those standards. Of course you have other advantages of the 20. You have much greater penetration of armor. The 20 will go through 3/4 inch of armor at 500 yards, while the 50 cal. will go through only 0.43. In addition to that you have one more great advantage-that is, you can have longer and more frequent bursts without damage to the gun with the 20 than you can have from the 50 cal. That is important for a strafing airplane, because they are burning up their barrels and ruining their guns on one flight. Sometimes it is long before that one flight is over. They will come down with screaming barrels and get trigger happy, and then all the barrels are gone in one flight. It should not happen in a 20mm. Of course, you have disadvantages. You have a heavier installation, one half as much armament for the same weight . Our standard ammunition in the Navy is 400 rounds in one gun. The Fleet has set up 30 seconds of fire as a minimum requirement for the 50 cal. gun. We can't do that with the 20s, so we give then 200 rounds. The 20 is lethal enough to get far more results out of that 200 rounds than the 50 ever will out of the 400 rounds."_

Cheers

Steve

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## Shortround6 (May 22, 2017)

Could I ask what is the date of the Patuxent statement ?


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## Greyman (May 22, 2017)

Shortround6 said:


> I believe the change in rate of fire could be achieved by changing just a few parts, including the buffer? and could be done at squadron level.



For what it's worth ...

British Browning .50 in. Gun manual (April 1942):
The speed of the gun, which is approximately 800 rounds per min., can be adjusted by regulating the flow of oil in an oil buffer.

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## Shortround6 (May 22, 2017)

Thank you.


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## stona (May 22, 2017)

Shortround6 said:


> Could I ask what is the date of the Patuxent statement ?


The conference ran from 16-23 October 1944


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## muskeg13 (May 22, 2017)

Too bad this wasn't developed sooner. It's claimed that it makes the .50as effective as a 20mm. Raufoss Mk 211 - Wikipedia


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## drgondog (May 23, 2017)

It became VERY clear even to USAF that the day of 50 Cal was at its end for air to air combat at high altitudes. NAA, for GUNVAL, converted 4 F-86E and 6 F-86F with the prototype M39's (IIRC). They lost one to flameout caused by blast gas and several flamed out but were restarted. That said, the limited experience in early 1953 sealed the fate of the M3. Also, IIRC the 6-3 wing replaced the conventional wing with LE Slats, improving speed and turn and climb, but higher landing speeds.

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## Shortround6 (May 23, 2017)

The statement from the Patuxent conference is helpful but hardly definitive.

It leaves a lot unsaid and uses a rather basic method of comparison between guns. As far as muzzle horsepower goes a 20 gauge shotgun slug .625 oz (273 grains) at 1580fps has less muzzle HP than a .220 Swift 48 grains at just over 4000fps. range and target effect are ignored.

I don't know if it was a result of the conference or the statement at the conference was a summation of what was going on in procurement but the Navy _ordered _*NO *new fighters armed with .50 cal guns after the fall/winter of 1944. They took delivery of thousands of aircraft already on order over the next few years but no new fighters or versions were planned with .50 cal guns.

I would also note that the M2A1 gun was starting production at around this time with a cycle rate about 100rpm faster than the M2 but was stopped after 8000 guns were made out of over 33,000 ordered( I have no idea if any actually went over seas) because of the progress on the T25E3 project which was _standardized _as the 1200rpm M3 in the Spring of 1945. First experimental T25E3 had been fired in July of 1944. We have no idea of _which _.50 cal gun the Patuxent statement is referring to. Also please note the above mentioned M23 round was in combat trials in the fall/winter of 1944 with rather mixed success.

Getting back to the Germans vs B-17s the German MG 151/20 had about twice the muzzle horsepower of the .50 cal gun and roughly 2/3rds that of the Hispano. It had a cycle rate (750rpm) somewhere between the Hispano (600rpm) and the .50 Browning (750-800)(book rates) and the synchronized guns in the FW 190 wing roots were probably about 10% lower than the "book" numbers.
The three common rounds the Germans used for air combat (others were used for surface targets) were
APHE, 115-117 grams at about 705mps with 4 grams of HE filler.
HEI/T, 113 grams at 705mps with 4.4 grams of he/incendiary material.
Mine shell, 92-95 grams at 800-805mps with 18.6-20 grams of HE. no tracer.

The last is what made the reputation of the MG 151 as a bomber destroyer. However it's light weight and poor ballistic shape meant it lost velocity quickly and while the trajectories/times of flight of the 3 rounds matched fairly well at close ranges the MG 151 was not a long range gun. Also the actual destructive effect of the MG 151 varied considerably with the mix of shells in the belt. Was the mine shell 33% of the load or 60% of the load?

The late 1944 .50 cal was using the M8API of about 43 grams at 880mps with about 1 gram of incendiary material. The .50 retained velocity better than _any_ 20mm projectile and had a significantly shorter time of flight at any but the shortest of ranges.

To compare guns/aircraft another way try comparing the weight of metal delivered per second. A P-47 with eight .50s firing at 720rpm will deliver 4.128 KG of projectiles per second.
A 3 gun FW 190 (one through the prop and two in the wing roots ) will deliver 3.864kg IF the belt is a 1 : 1 : 1 mix. Granted the German fighter is delivering more HE/incendiary.

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## Peter Gunn (May 23, 2017)

RE: Project Gunval, as I recall, there was an NAA engineer that solved the issue of flame-outs on the cannon armed Sabre by adding a small horseshoe shaped apparatus or clip at the end of the gun trough. I believe it broke up the gun gas and channeled or deflected it away from the intake. I could be wrong but I believe that solved the issue. 

Initially I think they tried a selector in the cockpit to fire only a pair of the guns at a time but that didn't work so well either, hence the horseshoe thing.

Also as a side note, those crazy Aussies stuck a pair of 30mm Aden's in their Sabres, on on each side, but I have no information if they had similar flame-out problems as the Gunval Sabres did.


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## GregP (May 23, 2017)

Mass delivered per second is just one of the factors in the Soviet "quality Factor" variable. I believe it takes into account the mass per second delivered, the kinetic energy, the explosive energy, (all the preceding add to it) and the weight of the gun (detracts from the Q factor). I may have left something out.

Google "The great Fighter Gun Debate" and read the article. If you create a spreadsheet to duplicate the values shown, you have the relationships. It seems like a very GOOD measure of a firearm, at least to me.


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## stona (May 24, 2017)

GregP said:


> Google "The great Fighter Gun Debate" and read the article. If you create a spreadsheet to duplicate the values shown, you have the relationships. It seems like a very GOOD measure of a firearm, at least to me.



I think you mean something like the table(s) to be found here

WORLD WAR 2 FIGHTER GUN EFFECTIVENESS

Cheers

Steve


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## GregP (May 25, 2017)

Actually no, but, that IS a nice table of characteristics. 

More like here: The WWII Fighter Gun Debate: Gun Tables . The Soviet Quality Factor is shown as "Q." When you do the spreadsheet and account for consistent units, the numbers come out quite well. A LOT of thought went into the Q factor, and it seems like an ideal metric for gun effectiveness to me, as an engineer.

Many things can be quantified in various ways. The Q calculation takes into account all of the important characteristics of any weapon firing projectiles from an aircraft. I say "from an aircraft," because the gun weight hurts the Q factor. If you were looking at a gun for a tank or a ship, weight might NOT be a factor at all and, for a tank, gun size would be much more of a factor than for, say, a ship. So, detracting from the score of the metric for a characteristic depends largely upon the intended use of the weapon.

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## Clayton Magnet (May 25, 2017)

Shortround6 said:


> A P-47 with eight .50s firing at 720rpm will deliver 4.128 KG of projectiles per second.
> A 3 gun FW 190 (one through the prop and two in the wing roots ) will deliver 3.864kg



What is the total weight of eight M2's plus ammunition as compared to the three MG151/20's plus ammunition? The 8 machine guns may throw as much mass down range, but the performance penalty imparted to the aircraft would make that a relatively poor arrangement.

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## Shortround6 (May 25, 2017)

The weight is a disadvantage of the .50 cal gun. It is one of the reasons the P-47 was as large as it was. However there are at least two other reasons so the entire difference cannot be charged up to just the .50 cal battery.
I would also note that the P-47 battery could fire for for over 30 seconds *IF *the ammo trays were full. They often were not in order to carry under wing loads/drop tanks but even the reduced capacity was good for 20 seconds or so. 
IF the wing root guns on the FW 190 have 200rpg they are good for about 18 seconds. Sources differ on capacity and actual rate of fire. 

Once you had the P-47 at the size it was taking out guns/ammo doesn't do much for performance. More change in climb that level speed or turn.

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## Clayton Magnet (May 26, 2017)

I think the Thunderbolt would have been better served by 4 Hispano cannons, but that is another thread, and the M2's did the job adequately. If the USAAF faced fleets of bombers like every other major combatant did, perhaps that would have accelerated the development of an American produced cannon. I seem to remember something about the US trying to develop a copy of the MG151/15, but nothing came of it. 
Then perhaps they would not have gone into Korea still armed with .50's


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## Shortround6 (May 26, 2017)

Please see: Welcome to Culver's Shooting Page

The US had literally dozens of gun programs going on during WWII. A wide variety of fast firing .50s. A wide selection of .60 cal guns and 20mm guns. Not all calibers stayed with one type cartridge. 

Select Volume 3A and start on page 4 for the.50 cal guns. A number of post war guns are included but the 40mm guns start on page 39.

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## pbehn (May 26, 2017)

I believe the British settled on 4 x 20mm canon for fighters sometime in late 1940/41. the Hurricane MkII, Mustang Typhoon and Tempest all had 4 x 20mm canon as did the post war Sea Fury. The exception was the Spitfire but this was simply because the canon require heating and ducting hot air to 4 guns. For the Hurricane Mk II it was clear that it couldnt compete with the Bf 109f in 1941 but it continued to be produced until 1944 not as a fighter but a ground attack aircraft


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## Shortround6 (May 26, 2017)

Clayton Magnet said:


> ..........Then perhaps they would not have gone into Korea still armed with .50's



as has been noted the USAAF went into Korea with 1200rpm M3 .50cal guns instead of the 800rpm (nominal) M2 .50 cal guns of WW II. 
They were also firing the M23 incendiary round at 1036m/s muzzle velocity instead of the older 870-890m/s velocity ammo. The M23 used a lighter projectile but it was filled with _six _times the amount of incendiary material as the M8 API round used in the last couple years of WW II. 

Granted the 20mm guns and ammo had also improved but the six guns on the Sabre were worth nine WW II guns and were delivering almost 720 grams of incendiary material per second compared to the 106 grams of incendiary material per second delivered by _eight _.50 cal guns on a P-47. 

They probably should have shifted to the 20mm like the Navy did but the .50 hadn't stood still.

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## GregP (May 28, 2017)

Guns had nothing whatsoever to do with the size of the P-47. The size was dictated by the turbocharger installation.







The pilot sat between the two hot tubs and the cockpit was warm. In Europe, this was a bonus in winter and disadvantage in summer. The wings were large enough to handle 8 x 50-cal plus ammo. This aircraft is currently flying.

Today, they just taxied another one that was recovered from a lake. EVERYTHING works, including the turbo! Dottie Mae!


_View: https://youtu.be/Rn_RuU4harA_


No pics yet ...

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## Shortround6 (May 28, 2017)

Greg, a P-47 with eight guns and 425rpg carried about 1335lbs worth of guns and ammo, now add the gun mounts, charging/firing systems, gun heaters and ammo boxes/feeds. 
An Armament system that heavy requires a larger fighter than than a 600lb armament system, even if just 20 sq ft of wing to carry the extra weight at 40lbs per sq ft. 

I did say there were two other reasons, *One* was, as you so nicely illustrated with the photos was the turbo system. The *second* reason was the 305 US gallons of fuel in fuselage between and under the cockpit and engine. roughly double the fuel of a P-40, or British Merlin powered fighter or a bit less than double what a Fw 190 carried. 
Try sticking three 55 gallons drums worth of MORE fuel _inside _any of those air craft and see how fat their fuselages get 
Again the weight may require a bigger wing than the fighter carrying 120-160 US gallons of fuel.










With the guns and ammo their wasn't a lot of room in the wing for fuel. The P-47N extended the wing and used the extra space for more fuel.




Not all of the 22 sq ft of added wing area was used for fuel but without the wing stretch fitting that amount of fuel in plane would have been very difficult. 

Sorry if I made it sound like the .50 cal battery was the main cause of the size of the P-47.

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## Shortround6 (May 28, 2017)

I Would also note that the Battery of eight .50 cal guns and the amount of ammo also helped fuel the requirement for the R-2800 engine and the 305 gallons of Fuel. 
If the Army had been happy with say, four .50 cal guns and 300rpg ( a weapons load of about 650lbs, not including accessories) then the required performance of 400mph at 25,000ft might well have been meet by using a smaller engine. The smaller engine would require both less fuel and a smaller/lighter wing to lift it. The smaller airplane would require smaller landing gear on so on. 

With the Army asking for six guns minimum and preferring eight the need for the R-2800 and the turbo was pretty much a done deal and the rest of the airplane followed. 

Please note that most other early war 2000hp class fighters with heavy armament were also big airplanes. Late war means better fuel and engines could provide the wanted power at less weight and volume. Also note that the FW 190 was _planned _for much less armament than it wound up with. What got shoehorned in later could be different than what the plane was planned around.


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## pbehn (May 28, 2017)

How many hits did all that turbo tubing need to make it inoperative?


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## stona (May 29, 2017)

Shortround6 said:


> Also note that the FW 190 was _planned _for much less armament than it wound up with. What got shoehorned in later could be different than what the plane was planned around.



True, but it was planned around a 1500 hp engine and for four rifle calibre machine guns (MG 17) and two 20mm cannon (MG FF/M) which was pretty good for a fighter of its time. It wasn't intended to be a night fighter and the fleets of US day time bombers wouldn't turn up for some time.
Cheers
Steve


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## drgondog (May 29, 2017)

The P-47 was 'late to the dance' to introduce increased internal fuel because a.) there was no way to introduce new 'extra' 70 gallon tank under the cockpit with a kit like the 85 gallon tank in the Mustang B and P-38J leading edge 55 gallon tanks, and b.) re-design the wing was a long lead time activity (P-47N). This is why the P-47D remained in Penetration and Withdrawal escort as the P-38J and P-51B took the target escort in March 1944 through VE Day, The 56FG P-47M and late P-47D with factory 70 gallon fuselage tank COULD have gone to Berlin after July with production P-47D-25, but at that time the decision was made to convert all P-47 and P-38 FG's (except 56FG) to P-51

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## Shortround6 (May 29, 2017)

I would note that the later P-47Ds had higher powered engines, although using water injection for take-off was questionable in 1943/early 44 (if ever?) , they got the paddle bladed prop and they may have had the benefit of longer runways than the P-47 planning of 1940/41 was allowing for. 
Point is that the operating conditions a plane works under could change quite a bit from those _envisioned_ when it was still on paper. 
It is those operating conditions, length of runways, take-off power, desired payload, range, performance and so on the help decide how big a plane is _when *designed. *_
As the conditions change the big plane gets more capable but it is also possible to build a smaller plane to do the original job if fuel, engines, propellers and runway conditions all change. 

Planes were usually the size they were for reasons that made sense at the time of design.

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## tomo pauk (May 29, 2017)

drgondog said:


> The P-47 was 'late to the dance' to introduce increased internal fuel because a.) there was no way to introduce a 70 gallon tank under the cockpit with a kit like the 85 gallon tank in the Mustang B and P-38J leading edge 55 gallon tanks, and b.) re-design the wing was a long lead time activity (P-47N). This is why the P-47D remained in Penetration and Withdrawal escort as the P-38J and P-51B took the target escort in March 1944 through VE Day, The 56FG P-47M and late P-47D with factory 70 gallon fuselage tank COULD have gone to Berlin after July with production P-47D-25, but at that time the decision was made to convert all P-47 and P-38 FG's (except 56FG) to P-51



There was never a 70 gal fuselage tank on the P-47. The type started with two fuselage tanks, main with 205 gals, and reserve (or 'auxiliary') with 100 gals, for obvious total of 305 gals. The main tank was made taller, thus gained 65 gals, for total of 370 gals per P-47. New main tank was introduced with the 'bubbletop' P-47D-25, from April '44.

There were several field mods, made by technicians of the 5th AF (CO being Gen. Kenney, who else), reportedly at August 1944. One added under-seat 42 gal fuel tank, another added the form-fitting 'slipper' tank of 'about 70 gallon'. Mods were abandoned due to aircraft becoming too heavy in take-off conditions (there was several accidents during the take off phase) with all of that plus drop tanks, plus the already increased factory tankage of 370 gals.


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## tomo pauk (May 29, 2017)

stona said:


> True, but it was planned around a 1500 hp engine and for four rifle calibre machine guns (MG 17) and two 20mm cannon (MG FF/M) which was pretty good for a fighter of its time. It wasn't intended to be a night fighter and the fleets of US day time bombers wouldn't turn up for some time.
> Cheers
> Steve



The Fw 190 was planned for two 13mm and two 7.9mm machine guns, all in the wing roots. With bigger wing installed while in prototype phase the plans for wing-mounted armament changed. Another change in armament was due to engine change. The new BMW 801 was longer and heavier than the initial BMW 139, thus, in order to have the CoG within acceptable limits, the cockpit was 'pushed' towards rear, thus making extra space between engine compartment and cockpit. That place was used to house 7.9mm guns and their ammo.
BTW - Fw 190 initially have had 1000 HP (if even so much) at 25000 ft, vs. P-47 2000 HP. Turbo was there for a reason, and it worked as advertised.


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## stona (May 29, 2017)

Also true, but I'm not counting anything before the A-0 as the armament developed along with the rest of the aircraft before a final production version was decided. The Spitfire wasn't planned to carry eight guns, but it too was altered at an early stage.
The V-2 did indeed get 2 x MG 17 and 2 x MG 131. The V-5 with the first 801 installation only had 4 x MG 17, but that doesn't mean it was a planned service weapon installation. The A-0 got the weapons that the A-1 would eventually carry into service.

Rodeicke gives the power of the BMW 139 as installed in the V-1 as 1500 PS Startleistung (1 min). Kurzleistung (5min) 1410 PS at 4,500m. Erhote Kurzleistung (30 min) 1270 PS, 4,900m. Dauerleistung 1150 PS, 5,400m. 
I'm sure that by 7500 - 8000 m it was struggling, but I can't put my hand on a chart..

Cheers

Steve


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## tomo pauk (May 29, 2017)

stona said:


> ...
> Rodeicke gives the power of the BMW 139 as installed in the V-1 as 1500 PS Startleistung (1 min). Kurzleistung (5min) 1410 PS at 4,500m. Erhote Kurzleistung (30 min) 1270 PS, 4,900m. Dauerleistung 1150 PS, 5,400m.
> I'm sure that by 7500 - 8000 m it was struggling, but I can't put my hand on a chart..
> ...



I've draw the red line that starts at about 4.5 km with 1410 PS. At 25000 ft (~7.6km) it can't make 950 PS.
Original graph represents 30 min (Steig & Kampfleistung) for the BMW 801C, with different lines for different level speeds (= different level of ram effect). 'Abgas-strahlshub' is exhaust thrust, in kg obviously.

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## Shortround6 (May 29, 2017)

We are back to _designed for_ and _developed to. _The German MG 17 may have been a bit heavier than the .30/.303 Browning but the ammo is close enough ignore the difference. The MG 131 was about 12kg lighter than a US .50 cal and the ammo was around 4kg per hundred rounds lighter (not including links/belt on either). The MG 131 apparently took a longer time to develop than planed forcing the substitution of other guns. The MG/FF cannon is actually about 1kg lighter than the .50 cal Browning although that may vary depending on accessories, the MG/FF does need the drum. 
An FW 190 with either four MG 17s and two MG/FFs or two MG17s, two Mg 131s and two MG/FFs is carrying little more, if as much, as a P-40C, in part because the P-40 was carrying 380rpg for the .50 cal guns, probably around 40kg too much. 

It is not until the FW gets the wing root cannon that it is carrying a really substantial load of weapons (referring to weight, not getting into an argument about effectiveness here). I would note that the FW 190 got a bigger wing after the first few prototypes in order to handle in the increase in Military load (or perhaps the 801 engine was heavier than 139?).


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## stona (May 29, 2017)

Shortround6 said:


> It is not until the FW gets the cannon that it is carrying a really substantial load of weapons (referring to weight, not getting into an argument about effectiveness here). I would note that the FW 190 got a bigger wing after the first few prototypes in order to handle in the increase in Military load (or perhaps the 801 engine was heavier than 139?).



The Fw 190 did get the cannon with the A-0, a '0' series being difficult to find a British equivalent for, a sort of prototype of the series production standard, certainly not a test or prototype machine like the V series. As a result the A-1 also had the wing root cannon. The Fw 190 was cannon armed from its earliest service incarnation.

The wing loading of the V-5 machine with the 801 series engine was 228 Kg/m2 compared with 187 Kg/m2 for the V-1 and this led to the larger wing being developed. Where the extra weight came from I don't know.

Cheers

Steve

Edited 'wing root cannon' to 'cannon'


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## tomo pauk (May 29, 2017)

Shortround6 said:


> ...
> It is not until the FW gets the wing root cannon that it is carrying a really substantial load of weapons (referring to weight, not getting into an argument about effectiveness here). I would note that the FW 190 got a bigger wing after the first few prototypes in order to handle in the increase in Military load (or perhaps the 801 engine was heavier than 139?).



801 was 160 kg/~350 lbs heavier than the 139.



stona said:


> The Fw 190 did get the wing root cannon with the A-0, a '0' series being difficult to find a British equivalent for, a sort of prototype of the series production standard, certainly not a test or prototype machine like the V series. As a result the A-1 also had the wing root cannon. The Fw 190 was cannon armed from its earliest service incarnation.
> 
> The wing loading of the V-5 machine with the 801 series engine was 228 Kg/m2 compared with 187 Kg/m2 for the V-1 and this led to the larger wing being developed. Where the extra weight came from I don't know.
> 
> ...



The Fw 190A-1 was with 4 MGs and two MG FFM cannons. A-2 got the wing root MG 151/20E cannons.
Item 7 lists ammo for the wing (root) MG-17s, item 8 lists ammo for the wing MG FF(M)s:


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## bobbysocks (May 29, 2017)

this is a chicken or the egg question....did they put 8 50s in the bolt because they had a plane with the size that could accommodate them or did they have the 8 guns as a requirement from the very beginning and have to build around that??


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## Shortround6 (May 29, 2017)

It's an egg, Nobody designs a fighter plane to be about 80-95% complete and _THEN _tries to decide what guns to put in it.
That is what the last part of this thread is about.
If you don't know what the payload will be (weight and volume of guns) it is mighty hard to design the airplane.

Please remember that the P-38 and P-39 _started _with two requirements, both wanted the same armament, the same speed, the same altitude. the Difference was that the requirement that lead to the P-38 required twice the endurance than the requirement that lead to the P-39. Just providing the extra fuel wound up leading to the two engines instead of one and all the rest. The P-38 and P-39 diverged form the initial requirements before they flew but that is where they started.

Doubling the guns from four to eight could mean adding 300kg or more to an aircraft, not to mention trying to fit in the gun bays. The P-47s landing gear shortened up 9in as it retracted to help leave room for the guns. See middle picture in post #61. Also see photo of original XP-47 with Allison. 




Also Seversky/Republic had orders for the XP-44 which was pretty much an XP-43 Lancer with the R-1830 taken out and a Turbo-ed
R-2180 of about 1400hp put in. Army _may _have wanted six guns on that one. P & W didn't want to fool around with the 14 cylinder R-2180 so that engine source dried up. 

Please note that the US Army requested some very heavy armaments in a number of proposals/prototypes that essentially doomed them. The whole Curtiss P-53/P-60 saga ( and even cutting the number of guns after the initial design/construction couldn't save them. Another eight .50cal fighter to start with.
Multiple 37mm cannon in the XP-54 is another one.


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## wuzak (May 29, 2017)

Shortround6 said:


> Multiple 37mm cannon in the XP-54 is another one.



I believe it was two, having started with only 0.50" or 0.50" and 20mm.

This change, along with the tilting mechanism for compensating the different trajectories between the 37mm and 0.50" guns installed, the pressure cabin, turbos, etc resulted in the empty weight of the XP-54 more than doubling. 

The XP-67 was to have 6 37mm.


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## stona (May 30, 2017)

tomo pauk said:


> The Fw 190A-1 was with 4 MGs and two MG FFM cannons. A-2 got the wing root MG 151/20E cannons.
> Item 7 lists ammo for the wing (root) MG-17s, item 8 lists ammo for the wing MG FF(M)s:



As I said, the type was cannon armed from its earliest service version. The cannon were initially in the outer wing position (outside the propeller arc for obvious reasons), not the wing root as I erroneously typed above (now corrected).








The armament varied through the V/A-0 aircraft.











Whatever the original intention, the armament clearly developed along with the rest of the aircraft.

Cheers

Steve


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## stona (May 30, 2017)

Shortround6 said:


> It's an egg, Nobody designs a fighter plane to be about 80-95% complete and _THEN _tries to decide what guns to put in it.



But they certainly alter the weapons requirement after the aircraft comes off the drawing board. Both the Spitfire and Hurricane were designed around four guns. The eight gun requirement was part of the conflation of various specifications. Both Hawker and Supermarine said they could fit eight guns (_"without trouble or delay"_ in Mitchell's words for what would become the Spitfire) but they were NOT part of the original specification about which both fighters were designed and amounted to a doubling of the armament. The original Hawker monoplane, which became the Hurricane was designed with two wing guns and _'two interrupter guns in the fuselage'_, eight wing guns is very different.
So whilst the Supermarine fighter was still at the mock up stage (not 80-95% complete) the Hawker fighter was more avanced, and required a completely new set of wings for the new armament. Fortunately the nature of the design made this more easy than it might otherwise have been. The initial idea was to build the eight gun wings as a back up plan, holding them_ "in reserve"_, but this was soon abandoned and we all know the Hurricane in its eight gun form.
To compensate for the increased armament the requirement to carry 4 x 20lb bombs was dropped and the endurance, i.e. fuel capacity/load, reduced.
Cheers
Steve

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## Shortround6 (May 30, 2017)

stona said:


> But they certainly alter the weapons requirement after the aircraft comes off the drawing board. Both the Spitfire and Hurricane were designed around four guns. The eight gun requirement was part of the conflation of various specifications. Both Hawker and Supermarine said they could fit eight guns (_"without trouble or delay"_ in Mitchell's words for what would become the Spitfire) but they were NOT part of the original specification about which both fighters were designed and amounted to a doubling of the armament. The original Hawker monoplane, which became the Hurricane was designed with two wing guns and _'two interrupter guns in the fuselage'_, eight wing guns is very different.
> So whilst the Supermarine fighter was still at the mock up stage (not 80-95% complete) the Hawker fighter was more avanced, and required a completely new set of wings for the new armament. Fortunately the nature of the design made this more easy than it might otherwise have been. The initial idea was to build the eight gun wings as a back up plan, holding them_ "in reserve"_, but this was soon abandoned and we all know the Hurricane in its eight gun form.
> To compensate for the increased armament the requirement to carry 4 x 20lb bombs was dropped and the endurance, i.e. fuel capacity/load, reduced.
> Cheers
> Steve



Thank you for the information, but it does help my point. It also comes back to what I call "the curse of the .50cal"

The British were _willing _to compromise armament (the bombs) and fuel load to get the guns/ammo they wanted in an existing design.
Without that compromise what would have been the result? 
A compromise of less performance?
A delay while a new aircraft/engine was worked on to give the desired performance with the desired weapons load?
A compromise that saw, air ministry officials cringing in horror, fighters equipped with something other than fixed pitch propellers 


Spitfire saw the introduction of the MK II with the Merlin XII engine which was a close match to the performance of the early MK I Spitfire. Th extra engine power was used up by the weight/drag of the operational equipment added to the Spitfire in the two years after it first entered service.
Had Mitchell been given a specification for a fighter with eight guns (350rpg) armor, self-sealing tank/s, bullet proof windscreen, rear-view mirror, IFF aerials and so on, and been limited to the Merlin II or III engine, would the plane have looked different to start with? 

The P-40 saw a small, but steady, decline in speed/climb from the P-40 to the P-40B to the P-40C with the fitting of more guns and protection. This was accepted by the customers. IF the Customer/s had _demanded _the performance of the P-40 with the armament and protection of the P-40C it would have required a new engine or a new airframe.

The "the curse of the .50cal" is that a single .50 cal with about 265-270 rounds weighs about 20lbs less than *four *.30/.303 guns with 334 rounds each. Just increasing the Ammo on the P-40's fuselage guns from 200rpg to 380rpg weighed about the same as a pair of .30cal guns with 500 rounds each.

If you want large batteries of .50 cal guns (6-8) with large amounts of ammo and you want to go fast high up, you need a big airplane. At least with the technology of 1941-41. 

The Mustang gained about 30% in take-off power between the early Allison model/s and the P-51D with the -7 Merlin. The gain in power at 25,000ft was near 100%. But the two-stage Merlin and 100/130 fuel were unknown to North American in 1940.


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## tomo pauk (May 30, 2017)

bobbysocks said:


> this is a chicken or the egg question....did they put 8 50s in the bolt because they had a plane with the size that could accommodate them or did they have the 8 guns as a requirement from the very beginning and have to build around that??



Two 'clusters' determined the P-47B/C/D etc. as we know it.
1st was the customer's requirement. Demanding the fighter that will have enough of firepower to bring down perceived enemy bombers appearing over the USA and/or it's overseas territories. The perceived bomber threat was expected to come in at high altitudes (USAF expected hi-alt bombers since they were in development in the USA itself), 20000-30000 ft, thus the new fighter was expected to fly & fight well there.

2nd 'cluster' were techincal & georgaphic realities of the day (1940-41 in the USA), ie. what is actually available in the moment, or it is in final phase of development. Heaviest weapon available that will fit in the reasonably thin wing (14% T-t-C ratio at the root) was the .50 BMG. Heavy firepower = plenty of those, with plenty of ammo -> great weight of firepower installed. The most powerful engine of the day was the R-2800, big and heavy lump of metal. In order to make plenty of power at high altitudes, it needed turbo system. Many HP = voluminous turbo ducting, intercooler and turbocharger itself -> again weight goes up. Powerful engine needs plenty of fuel, and USA was and is a big country the new fighter to defend, thus P-47 initially carried 3 times the fuel of Bf 109, Spitfire or Hurricane. All of these weight gains and customer requirements = will need a big wing, almost twice the Bf 109, or around 50% greater than the FW 190.

Republic managed to design a fine aircraft around these requirements and available techy stuff, even if we recall that P-47B was a problem no less of a problem that it was early Typhoon or early Fw 190, the P-47B never went into combat due to airframe- and engine-related problems .

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## stona (May 30, 2017)

Shortround6 said:


> The British were _willing _to compromise armament (the bombs) and fuel load to get the guns/ammo they wanted in an existing design.
> Without that compromise what would have been the result?
> A compromise of less performance?
> A delay while a new aircraft/engine was worked on to give the desired performance with the desired weapons load?
> A compromise that saw, air ministry officials cringing in horror, fighters equipped with something other than fixed pitch propellers



I think the Air Ministry had to compromise. Aircraft design was moving very fast in the mid 1930s and there were several specifications which needed somehow bringing together. The distinction between 'zone' and 'interceptor' fighters was becoming blurred, which had a fundamental impact on the endurance required of what would become the Spitfire and Hurricane) and the never ending quest for both firepower and speed was also leading to compromise. When they went to eight guns they also reduced the ammunition requirement per gun from 500 to 300 rounds.

It is worth mentioning that as early as April/May 1935, when the idea of eight guns, all in the wings, was being discussed, Hawker was quite keen to do away with the fuselage guns as the company was worried about making them work with the _'3-balded VP airscrew'_ which they proposed to use.
Given the discussions around both the Hawker and Supermarine fighters, and at Rolls Royce and Bristol, about variable pitch propellers (or sometimes controllable pitch in the language of the day) the fact that Fighter Command's two principle fighters did not get a proper CSU until 1940 is a 'just in time' that did not need to be such.

Cheers

Steve

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## Shortround6 (May 30, 2017)

The fighters (and actually all aircraft) also had to meet field requirements like take-off distance to certain height and landing speeds and landing distance. Wings and flaps and slats/slots were also going through a *very *fast evolution at the time.

Spitfire "flap"





There were no intermediate positions, at least on the early Spitfires (MK IX and earlier?) It was all or nothing. Lost through the years since WW II is the terminology of the time when plain flaps were sometimes called "_drag _flaps" as the idea/effect was to increase drag and they had very little to do with lift. Nowadays we might call them air brakes and not be far off. They steepened the glide path on approach but did nothing for take-off so the big wing was needed for take-off performance. 
In just a few years (3-4) flaps had advanced to multi-position- Fowler flaps- Zap flaps -slotted flaps and a few others that could do a variety of things. 

On the gun issue " When they went to eight guns they also reduced the ammunition requirement per gun from 500 to 300 rounds."

Weight of the 303 ammo was roughly 6lbs per hundred so that savings in weight was about 96lbs or call it 100lbs which shows how tight the designs actually were. If they were worried about 100lbs while still in the design stage they certainly were NOT designing an airframe and THEN seeing what they could stuff in it.


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## tomo pauk (May 30, 2017)

stona said:


> As I said, the type was cannon armed from its earliest service version. The cannon were initially in the outer wing position (outside the propeller arc for obvious reasons), not the wing root as I erroneously typed above (now corrected).



Indeed, the 1st service version (A-1) was cannon armed.
My idle thinking - many RAF airmen survived due the A-1 not being outfitted with 4 cannons (whether MG FFM firing outside the prop arc, or MG 151 in different 'flavors' and installations), while 2 x 60rpg was certainly not enough for the needd envisioned.



> The armament varied through the V/A-0 aircraft.
> ...
> Whatever the original intention, the armament clearly developed along with the rest of the aircraft.



Agree pretty much.
We can see in the tables that it took the 'big wing' to be developed in order the Fw 190 carry wing cannons. Original wing on the 1st prototypes was even smaller than what the Bf 109 had.


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## stona (May 30, 2017)

With concessions made on the bomb load, fuel and ammunition, Mitchell estimated that the eight gun Spitfire would be 180lb lighter than the four gun version. Of course no service version ever came close to those projected weights, all being substantially heavier.

One of Mitchell's claims for the relative ease with which the eight guns could be fitted in the wings was that his elliptical design would allow the gun breeches and ammunition containers to be close to the aircraft's vertical datum, so that the expenditure of ammunition would not adversely effect fore and aft trim. On an aircraft as small as the Spitfire I believe every pound was considered as the design developed.
Barrie Bryant, who took employment with Supermarine in October 1939, remembered that as a junior member of the technical office his job involved weighing or calculating the weight of every part of every sub assembly they designed. By the mid 1940s he would write:

_"That left me as custodian of weight and balance records and recipient of growing weight work on Walrus, Sea Otter and Spitfire in its many variants, experimental and production...A year later I acquired an assistant, the first of an eventual 30 strong Weight Section. Our duties eventually included the prediction, calculation, verification and monitoring of weight, balance and moments of inertia of aircraft from conception to operational use; initiation of weight reductions; preparation of loading data; development of prediction methods; training design staff."_

The Seafire 47s did have a three position flap IIRC, an intermediate 'take off' position was added. This did away with the disposable wooden wedges used to give 10 or 15 degree down against the return springs on earlier versions for carrier take offs.
I would guess that the reason for the two position flap is that it was what was required at the design stage for landings on grass aerodromes and anyone familiar with the pneumatic/spring operation of the system would understand why it would need a substantial redesign or replacement to operate as a multi position system. The Spitfire wing is notably devoid of any devices to increase lift. The Spitfire prototype had a 60 degree flaps down angle, this was later increased to that above (85 degrees)
I have read accounts of the development of the Spitfire by Shenstone, the three Fs (Faddy, Fear and Fenner) as well as Smith and various others and I don't remember any of them even mentioning the landing flaps! Both Quill and Summers mention that Summers raised and lowered them on the first test flight (the undercarriage stayed down as per his instructions) but apart from that nobody seems to have been concerned with them.

Cheers

Steve

Edit, checked flaps down angle 85 degrees


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## stona (May 30, 2017)

Shortround6 said:


> They steepened the glide path on approach ...



The British called that "reducing the flatness of the glide" 
Cheers
Steve


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## Shortround6 (May 30, 2017)

Ah, yes. The English and the Americans, two peoples divided by a common language

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## VALENGO (May 30, 2017)

Maybe someone said this before: over the green bar showing the votes for Focke Wulf, it is written Fw109 instead of 190. Cheers.


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## stona (May 31, 2017)

pbehn said:


> I believe the British settled on 4 x 20mm canon for fighters sometime in late 1940/41.



Specifications for fighters armed with four 20mm cannon or eight machine guns are almost exactly contemporary, dating to 1934/35.
It is worth pointing out that this proposed armament was FAR in advance of the armament being specified by other air forces at this time.
The initial results were the Spitfire, Hurricane and Whirlwind.

In the case of the British it was the stubborn adherence to the belief that bomber formations would be able to defend themselves from attacks by fixed gun fighters, however heavily armed, that led to the development of multi seat fighters which were judged to offer the hope of breaking up those formations. The end product of that line of development was the Defiant which when confronted unexpectedly by single seat fighters was outclassed by them, with predictable results (Dowding had predicted them). How it might have fared in a campaign against unescorted formations we will never know.

By the time the Germans were confronting the B-17 it had been established that even the most heavily armed and armoured bombers could be vulnerable to attack by fixed gun fighters, and those fighters became very heavily armed indeed.

Cheers

Steve


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## Shortround6 (May 31, 2017)

Unfortunately this doesn't hold up well when one considers the "possibilities". 
The Defiant might have worked well when used as intended against bombers with rather pathetic defensive armament.
Like Early He 111 and Do 17s with three rcmg (rifle caliber machine guns) per plane in manual mounts. However _expecting _your opponents to offer up such targets was perhaps optimistic? It did work out well for the British that the Germans were slow (glacial?) in providing better defensive armament (an no 3-4 separate guns manned by one gunner who bounced between them was not that big an increase in effectiveness).

One wonders how well the Defiant would have done against bombers equipped with power turrets mounting 2-4 rcmgs each or even the French bombers with a 20mm gun in the dorsal power turret? 

One also wonders at thinking that four .303 guns, no matter how well aimed/directed would be so much more effective than double the number of fixed guns in a single seat fighter 1/2 the firing time needed to put the same number of rounds on target so lethal damage might be done in a firing pass vs a broadside engagement? 

Once again I refer to WW I practice in which twin gun mounts on bombers, if not very common, was at least somewhat wide spread. 
Why bombers built 15-20 years after WW I ended reverted back to single guns is something of a mystery. 



The German fighters with even a pair of 20mm MG/FFs offered a fair amount of fire power against the early British bombers and the early Wellingtons that suffered so badly had a pretty dismal armament set-up if I recall. The early twin mounts (not turrets) offering restricted traverse and elevation? In any case much smaller fields of fire than the later Frazer-Nash turrets. The Hampdens started with the same three rcmgs as the German bombers in manual mounts. 

The B-17s did force the Germans into using several different tactics/weapons that the British had not had to resort to (or had time to develop?) in the BoB. The underwing gun pods to increase fire power but left the fighters vulnerable to escorts? (shades of the Defiant, the bomber interceptor cannot handle escort fighters?) the large rockets to break up formations so the interceptors don't have to face formation firepower? The use of large twin engine interceptors to carry enough fire power? 

In the end the self defending bomber was a failure or at best a very limited success but it took several years of development of fighters, bombers and guns to reach the final but inevitable conclusion. A single seat fighter was always going to be able to carry a heavier armament than any one or two gun stations on a bomber and since the single engine/single seat fighter is much cheaper than a bomber in a war of attrition the bomber comes out on the loosing end.


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## stona (May 31, 2017)

When considering the British fixed gun fighter armament proposed in 1934/35 it must be compared with contemporary armament from other nations.The Bf 109 did receive cannon armament by 1940, but in the immediate pre-war period, when the Spitfire and Hurricane were carrying eight rifle calibre machine guns it carried just two (or three). Design of the Fw 190 started in 1937/8 making it a contemporary of the Air Ministry's specification F.18/37. That specification called for twelve machine guns whereas initially the Fw 190 was to have just four.
French fighters were among the most heavily armed, often with four rifle calibre machine guns and a cannon, they too made a big jump from the two machine guns prevalent in the early 1930s.
Japanese, mid 1930s, two rifle calibre machine guns.
As for the Americans, the P-36, a near contemporary of the Hawker Hurricane, only had two machine guns. The P-40 first flew in 1938 armed with just two .50 calibre machine guns (more rifle calibre guns added later).

The British worked out that, according to them, the number of fighters attacking a bomber formation would number at most 1/3 the number of bombers in that formation. Based on this formula each fighter would be required to develop at least four times the firepower of one bomber from the rear gun. When the sums were done, in late 1933, the typical rear armament of a bomber (including the latest British specifications) was just one gun, so four guns in the fighter seemed reasonable. The reasons that this was soon raised to six or eight had more to do with newer concepts of air fighting, times of engagement and rate and weight of fire required rather than anything the bombers carried. These did not apply to the turret fighter and this is why it, unlike its fixed gun counterparts, retained four machine guns. Had the Defiant proved a success, then it would have received a turret with two 20mm cannon, this was the only sensible suggestion to come out of the debates of the mid 1930s about turret fighters. Efforts had been made to develop a cannon armed turret fighter, in 1936 the Operational Requirements branch suggested replacing the four machine guns of the Defiant with four cannon but both Dowding and Freeman doubted this was possible. This led to another debate about forward firing armament, nose turrets and even a twin engine design, all of which came to nothing.

Cheers

Steve


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## Shortround6 (Jun 1, 2017)

Well somebody was smoking the wacky weed?
replacing 10KG .303 guns with 50KG 20mm Hispanos even on a two for one basis wasn't going to work.
The turret with four 20mm cannon needed a twin engine plane a pretty big one at that.

Twin 20mm turret on an Avro Lincoln.








Trying to stick one of these on Defiant ( or even a slightly up-scaled Defiant ) is going to present big problems. Once they started figuring out the drag of those large gun barrels elevating and traversing on a much smaller plane than a four engine bomber the idea became a lot less attractive.








Boulton Paul P92 with either two Vulture or Sabre engines. There were proposals form other companies. 

A lot of time and money seems to have been spent on a "theory" as so far any actual firing trials have not made it into the popular press or accounts, perhaps they were done and are buried in the archives?


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## stona (Jun 1, 2017)

When the Operational Requirements Committee discussed a new turret fighter in 1936 there were two options on the table. One was a re-incarnation of the Ellington type, a three seater with two twin cannon turrets, one amidships and one in the nose and as of 16th December 1936 this was the preferred option. The other option was a development of the Defiant, with a four 20mm cannon turret amidships, but now a twin engine design, allowing the single turret to meet the requirement for forward firing armament. As of March 1937 this became the preferred option. Dowding expressed doubts about getting four 20mm cannon into a turret and was told that a high wing monoplane with the turret merged into the top of the wing was envisaged. This must surely be the P.92. The designation of the new turret fighter was changed from F.18/36 to F.11/37 and an Air Staff Requirement was issued in May 1937. Later in 1937 another specification F.9/37 was issued to Gloster for a twin engine fighter with a nose turret set up for no allowance shooting (it still hadn't been abandoned) and a four gun turret amidships. These two were now the only runners for a cannon armed turret fighter.
Just to show how enamoured the Air Ministry was with the turret concept, despite little progress being made on any of the earlier specifications, and the turret being dropped from F.9/37 (to Gloster) yet another specification was issued in early 1939. F.2/38 (yes, 38) called for a four cannon nose turret capable of firing in a limited arc, but considerable angles of depression, really another re-incarnation, this time of the Novel Fighter concept. Before anything got done someone suggested that the upper turret of the B.1/39 specification (the Ideal Bomber) might work with this aircraft in place of the nose turret. A turret first proposed for a fighter (F.18/36 and F.11/37) but then specified for a bomber (B.1/39) was now proposed for yet another turret fighter (F.2/38). Are you with me so far?  This turret fighter project, previously F.2/38 was redesignated F.26/39.
To sum up, in efforts to develop a cannon armed turret fighter the Air Ministry issued all the specifications above. Not one of them led to a completed turret fighter. The Defiant, machine gun armed, was the only one to reach the RAF.
Cheers
Steve


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## Shortround6 (Jun 1, 2017)

Perhaps I am being too hard on the British. 
The Americans certainly poured a crap load of money into the rocket armed bomber interceptors in the early 1950s with little results in actual tests. Fortunately the guided missile (poor as the early ones were) was able to take over from the unguided rockets. 

Both countries seemed to have jumped the gun on what was technically possible or assumed that the engineers could develop the hardware fast enough to bring the theory into service fairly quickly.

However I still can't understand the guys who thought they could build turrets will multiple cannon (or even multiple turrets) without huge penalties in weight and drag. That is simple physics or mechanics, ship designers since before WW I figured the weight of a gun and it's mounting went up with the cube of of it's caliber (not including armor) I don't know why an aircraft turret should be much different in early estimates. 

Dowding may have been going by hunch or gut feeling but he was closer to reality than the guys pushing this theory.


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## stona (Jun 1, 2017)

I don't know whether anything other than mock ups of these turrets were built in the period from 1936-1939. I don't think they were. One things for sure, the entire concept of turret fighters died in 1940, though the cannon turret itself didn't.

To be fair to Dowding, he was also one of those expressing reservations about the entire turret fighter concept long before they were revealed, as early as 1933, when the idea was gaining momentum through the 'Novel Fighter' competition and Ellington's own preference for some kind of turret armed fighter to engage bomber formations. 

Cheers

Steve


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## pbehn (Jun 1, 2017)

All this tlk of canon armed turret fighters while the bombers carried turrets with rifle caliber guns throughout the war.


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## Milosh (Jun 1, 2017)

The Brits weren't the only ones.


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## stona (Jun 1, 2017)

pbehn said:


> All this tlk of canon armed turret fighters while the bombers carried turrets with rifle caliber guns throughout the war.



The British were looking for ways to increase the firepower of their fighters in the mid 1930s which is why all the fixed gun fighters got many machine guns and/or cannon armament. The logical up-gunning of a turret fighter was to use cannon, you can only fit so many machine guns in a turret and two cannon give much more 'horsepower' (to use an Americanism) than four machine guns.

British bomber armament was also much discussed, the balance between defensive armament, weight and speed being the principle debate. When Ellington saw the heavy bomber requirement (B.12/36) he asked for 20mm cannon armament to be considered, the Air Staff decided against it. One year later the Deputy Director Operational Requirements (DDOR), Oxland, who had argued against 20mm cannon for B.12/36 was advising the Plans branch of the Air Staff that bombers in the near future would require 37- 40mm cannon armament. This was something of a volte-face, but Oxland seems to have got away with it. This requirement was confirmed in a review of bomber armament in June 1938.
The 'Ideal Bomber' would have had cannon armament had it ever got built and had a suitable turret been developed (big ifs). The switch to night time bombing rendered almost all previous planning irrelevant. Though the prospect of a return to day bombing was always acknowledged it didn't happen until the opposition had been effectively destroyed, by the Americans. The RAF's war time bombers retained their machine guns throughout.

Cheers

Steve


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## Shortround6 (Jun 9, 2017)

I found the cutaways of the.50 bullets I mentioned earlier.




This not all of the different .50 cal bullets used during WW II/Korea but one can certainly see the difference in the amount of incendiary material carried by the M23 and how it was done. One can also see why they might have problems with it as there is very little wall thickness to either support the projectile on firing or insulate the incendiary material from the hot barrel. 
Flaw in the jacket or steel cup? Rough spot in the bore? Barrel is hot from a long burst? Incendiary material ins't 100% on spec? 
Combination of the above?

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## drgondog (Jun 10, 2017)

Great find Shortround. This has been a mystery for a very long time. I couldn't discount dad, Henry Brown and others recount of flawed "HEI" 50 cal bursting shortly after leaving the barrel. Thanks for digging.


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## Shortround6 (Jun 10, 2017)

I would say that the M23 is the most likely answer. It was known to act like you describe, it was in Europe at the time in small amounts.
I have not read about any true HE .50 cal projectiles but that doesn't mean they didn't exist, just rarer than the M23. 
I have no idea if the M23 was even called the M23 in 1944/45 or went by a different designation like XM____ or T__E_ or something. 
What the armorer's or weapons officers told your father and his squadron mates I obviously have no idea either. ALL possible points of confusion. 
The M23 carried roughly double the amount of chemical payload that the German/Italian/Japanese HE or HEI 12.7-13mm projectiles did so having them "light up" just in front of the gun muzzles was probably a "significant event" for the pilots involved.


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## drgondog (Jun 11, 2017)

The 'significant event' as Henry brown described the first (and only) use was that he thought a barrage of flak erupted in front of him when he started a strafing run.


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## Shortround6 (Jun 11, 2017)

Yep, definitely get your attention and/or require a trip to the laundry 
not to mention a 3:00 am meeting behind the outhouse with the guy who authorized the use of the ammo  

This does look like the most promising explanation of the experiences of your father and his friends unless an unknown round makes a sudden appearance.

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