# Turret Fighters



## wuzak (Aug 26, 2014)

With hindsight, we know that turret fighters basically went nowhere during World War II.

In discussion over the merits of Supermarine's Type 327 cannon fighter the following was put forward:



> RD Arm stated that it might be helpful to place on record that it had now been found that the bomber was not very vulnerable to .303 fire from astern, thus discounting the value of the fixed .303 gun fighter.



And



> The turret type offered particular advantages overseas and for Field Force operations, whereas, the fixed gun type would suffice over home territory, where defensive power was unecessary. The turret type might eventually be found to cater for both purposes but they had to bridge a gap of about 3 year which must ensue before the turret type could be developed.



These are from notes of a meeting held on November 24, 1938.

Also mentioned was the F.11/37 program (Boulton Paul P.92) and another turret fighter specification to be added to that year's (1938) program, though I can't find a reference to that.

The F.11/37 fighter was to carry 4 x 20mm cannon in its turret.

This clearly shows how enthusiastic the RAF and Air Ministry were for turret fighters. With hindsight we can say that their logic was faulty and led to a dead end. But in 1938, without having experienced war with modern monoplanes (as Germany had in Spain), was their thinking sound?

Bearing in mind that they had already started the Whirlwind project F.37/35, the Gloster F.9/37 and were considering the Bristol Beaufighter proposal, all of which had fixed 20mm cannon armament.

Perhaps they were having a bet each way?


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## stona (Aug 26, 2014)

The turret fighter 'theory' was fine for intercepting unescorted bomber formations. An almost naval type of engagement was envisaged in which the turret fighters would fly alongside the bomber formation attacking with enfilading fire from their turrets.
Some had doubts it is fair to say.







And this was BEFORE the fall of France which enabled the bomber formations to arrive in UK air space escorted by 'zerstorer' _and_ single engine fighters, something nobody had anticipated.

A further problem was that the ability of the current production turret fighter (Defiant) to actually make an interception of bombers travelling at the speeds of the late 1930s was doubted.






The concept was dead in the water by late 1940 and so unfortunately were all too many turret fighter crews.

Cheers

Steve


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## Shortround6 (Aug 26, 2014)

Was this for bomber defense or for bomber interception?











In early 1939 Vickers submitted a scheme for mounting the gun in a large dorsal turret in a Wellington ‘heavy fighter’ with a predictor and a rangefinder. Such an aircraft it was claimed, could engage hostile formations at a range well beyond that of the fighters’ defensive fire.

Granted the Wellington may have been used as a test rig and the 'service' aircraft would have been a higher performance machine.


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## wuzak (Aug 26, 2014)

Shortround6 said:


> Was this for bomber defense or for bomber interception?
> 
> View attachment 270337
> 
> ...



Wasn't that with the 40mm Vickers S gun?


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## stona (Aug 27, 2014)

Surely that Wellington reflects the same philosophy, that it would engage an enemy formation, in this case at range, whilst flying alongside it. It really was a ludicrous idea with hindsight as remaining outside the effective range of the formation's defensive fire certainly wouldn't protect it from a marauding escort. Even at the time these proposals were being made the Luftwaffe had the Bf 110 to do this. From airfields in western Germany (say around Dusseldorf/Cologne) to south eastern England is only about 500 km (310 miles).

If the RAF were worried about a Defiant being quick enough to make an interception of an enemy formation flying at 230 mph the Wellington had absolutely no chance. I'm not surprised that nothing came of the proposal.

Cheers

Steve


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## Siddley (Aug 27, 2014)

What was the average speed of a Luftwaffe bomber formation during the Battle of Britain ? I know the document says 230mph but it's dated January 1940


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## stona (Aug 27, 2014)

The same bombers were flying in the BoB a few months later. A formation has to cruise at the speed of it's slowest component and the Luftwaffe types involved in the BoB were all comfortable at around the 230-240 mph mark at the range of altitudes they came in at. That's probably why Fighter Command based the anticipated speed of incoming formations at this level in the January document.

Planning for this had started years earlier, it's why the Spitfire Mk 1 was a 350mph fighter and the Hurricane just a little slower.

Cheers

Steve

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## yulzari (Aug 27, 2014)

I recall the 40mm S gun Wellington being discussed elsewhere some years ago. IIRC the idea was for the bomber to be able to engage attacking fighters beyond the range of the attackers fire. With the rangefinder and predictor it was, effectively, a flying anti aircraft gun. The vulnerability of bombers from attack from multiple directions, especially below, was being found at the same time so it was shelved. With a 40mm HE round on a lightweight fighter it was a one hit one kill. The geodesic structure of the Wellington proved ideal as the forces were distributed along the members into the entire fuselage structure. When they tried the same gun in the front of a Flying Fortress the nose structure was not up to the challenge.


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## vikingBerserker (Aug 27, 2014)

I am not so sure turret fighters went nowhere. The P-61 seemed to have enjoyed some success.

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## stona (Aug 27, 2014)

One hit one kill for sure but what chance did the Wellington have of hitting a 350 mph fighter before it got a shot in? The problem becomes even more difficult if several fighters attack at once.
Many US bombers were equipped with many more guns which out ranged those of the attacking fighters, but it didn't save them, even in defensive formations.

How many P-61s actually got the turret?

Cheers

Steve


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## nuuumannn (Aug 27, 2014)

> How many P-61s actually got the turret?



The first 37 P-61As had the turret, but it was removed from those because of buffeting, I think, when the turret was turned in flight, but the final 250 P-61Bs of 450 built were fitted with the turret, presumably the buffeting issue being cured.

In hindsight, the turret fighter was not the best idea, but even though the Defiant didn't set an altogether rosy example, the British Air Ministry did not let the turret fighter die quite so quickly as is often led to believe, after August 1940. Turrets were a novelty during WW2 and the British were the first, as we know, to apply them to in-service aircraft. Not all the combatants had the know-how to produce effective technology from the outset, so not everyone adopted the idea (powered turrets in general, that is). Regardless of what we think of the turret fighter idea today, back in late 1940, and this is after the Defiant was deemed a night fighter only, the turret fighter idea had many proponents. It is also worth remembering that the British were also conceiving fitting turrets to everything they could, believing they had the key to an advanced and more effective weapon system.

A list of turret fighter specifications issued by the British Air Ministry:

F.9/35, which produced the Defiant and Hawker Hotspur: other companies to submit tenders include Bristol, Fairey, Gloster, Supermarine and Vickers. Armstrong Whitworth produced a twin and BP produced an alternative to the Defiant.
F.11/37 for a two-seat twin engined turret fighter, this produced the BP P.92, which was never built, but a flying scaled down test bed was built. Other firms include AW, Bristol, Gloster, Hawker.
F.18/40, this was initially issued as a fixed forward firing cannon armed, two-seat night fighter spec, but on 9 December 1940 the spec was amended to include a turret. The aircraft also had to be fitted with radar. BP produced an enlarged Defiant with and without the turret with either a Sabre or Centaurus powerplant as well as a podded twin that looks just like the P-61, Fairey, Gloster, Hawker, Miles and Vickers all submitted proposals. Gloster produced the Reaper to this spec. 

Bristol modified a Beaufighter by fitting it with a turret in mid 1941 as a stop gap, but it was found that it was slower than the Defiant it intended to replace, so it wasn't progressed with. De Havilland was suggested that the Mosquito be fitted with a turret, but GdeH scoffed at the idea and a mock-up was produced but not progressed with. It's interesting to note that when GdeH was first proposing the DH.98, Sholto Douglas insisted that the high speed bomber be built with a rear turret and at one stage this was going to be produced, despite GdeH's protestations that the turret would knock some 30 mph off its top speed, with the unarmed prototype being a concept demonstrator only. Luckily common sense and the efforts of Freeman caused a change of heart, although this was still the status quo by the time the prototype flew for the first time.

The Mossie played a big part in the death of the turret fighter idea in Britain; after 1940, it was no longer considered a good idea for a day fighter, but as a night fighter the concept had more impetus, as can be seen with the experiments to the revamped F.18/40. All this came to nought because of how good the Mossie turned out to be.


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## wuzak (Aug 27, 2014)

Interestingly, when testing the turret in a Mosquito (W4053 IIRC) it was found that the motors weren't strong enough to turn the turret and it got stuck in position at speed. John de Havilland was trapped in this manner during one test flight.

Also note that the turret prototypes were fighters - if they put turrets in the bombers there wouldn't be the space and/or capacity to carry bombs.


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## nuuumannn (Aug 27, 2014)

> lso note that the turret prototypes were fighters - if they put turrets in the bombers there wouldn't be the space and/or capacity to carry bombs.



That's right, the turret armed DH.98 bomber was never built and it was to be a tail turret, so wouldn't impinge on the bomb bay.


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## GrauGeist (Aug 28, 2014)

The turret concept on a single engined aircraft was not completely dismissed by the U.S., the Navy's TBF(TBM) had a turret where it's predecessors had free gunmounts.


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## rank amateur (Aug 28, 2014)

I wonder if the TBF Avengers' turret was more effective than for instance the gunmouth in the Helldiver or the Dauntless. Would anyone have info on that? Well obviously a .50 has more impact than a .30 but besides that I mean.


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## swampyankee (Aug 28, 2014)

rank amateur said:


> I wonder if the TBF Avengers' turret was more effective than for instance the gunmouth in the Helldiver or the Dauntless. Would anyone have info on that? Well obviously a .50 has more impact than a .30 but besides that I mean.



I think the effectiveness of the defensive armament on the TBF and SB2C can be estimated by the fact that their successor aircraft, the AD and AM had no gunners.

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## pinsog (Aug 28, 2014)

By the end of WW2 in the Pacific, you could probably have flown a Piper Cub on most attacks, Japanese fighters weren't much of a problem at that time because at that time all naval bombers were escorted by huge swarms of Hellcats and a few Corsairs. Defensive gunners probably slept the whole trip hoping they weren't shot down by ground fire or crash into the back on the carrier when they got home. 

Now, back during Midway, I'm would imagine that all those US torpedo crews would have welcomed the Avenger, with its speed, armor, self sealing tanks, and that turreted Browning 50 in the back. A few more might have made it back alive.


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## fastmongrel (Aug 28, 2014)

pinsog said:


> Now, back during Midway, I'm would imagine that all those US torpedo crews would have welcomed the Avenger, with its speed, armor, self sealing tanks, and that turreted Browning 50 in the back. A few more might have made it back alive.



There were 6 Avengers that flew at Midway. 5 shot down and 1 barely making it back to the deck with a dead gunner and an injured pilot and navigator. Without fighter cover and a mix of bad luck and bad tactics I doubt having all the USN torpedo squadrons in early model Avengers would have made a great deal of difference.


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## Glider (Aug 29, 2014)

The only turret (ish) fighter that I know that had any success was the Bristol


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## stona (Aug 29, 2014)

Glider said:


> The only turret (ish) fighter that I know that had any success was the Bristol



To be fair to the Defiant it did enjoy some limited success in its role as a makeshift night fighter.

Cheers

Steve


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## nuuumannn (Aug 29, 2014)

> o be fair to the Defiant it did enjoy some limited success in its role as a makeshift night fighter.



More than limited success. Between end of 1940 and mid 1942, Defiant night fighters had a better kill to intercept ratio than any other British night fighter. Let's look at the stats. Between December 1939 and August 1940 it served as a day fighter, entering combat on 13 May 1940 for the first time during the day and on 28 August the last time as a day fighter. it's first night intercept was made in September 1940 and the last on 18 April 1942. The last Defiant fighter squadron was also the first, 264 Sqn relinquishing its last Daffys for Beaufighters in mid 1942. So, for two thirds of its frontline career it served as a night fighter, a job it did reasonably well, in fact, statistically there were a greater number of Defiant night claims than any other British night fighter type in that time (September 1940 to April 1942), so it's safe to say that success was a little more than limited.

24 credited aces scored kills on Defiants in that time, although not all of their kills were made in the Defiant. Only six individuals became aces on the Defiant, of those five of them were Defiant day fighter aces.


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## stona (Aug 29, 2014)

It had limited success in terms of enemy aircraft intercepted and destroyed. Comparing it to other British night fighters is not a very valid measure of success. It may have done better than the Blenheims or early Beaufighters, I haven't looked at the relative numbers of the various types employed.
Cheers
Steve


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## nuuumannn (Aug 29, 2014)

> Comparing it to other British night fighters is not a very valid measure of success.



I don't really see why not. Night fighting was not an advanced science at the time, as you know and few other air forces had as much experience as the RAF in night fighting within that time period. It took the Germans time to get their aircraft and crews to a creditable standard, so by the standards of the day (or night) the Defiant was quite successful. I guess I have to ask, what you would use to qualify as being more successful _at that time_ than the Defiant?



> It had limited success in terms of enemy aircraft intercepted and destroyed.
> 
> 
> > Compared to what? You go to war with the weapons you have, not what you want and the Defiant, although awaiting replacement by better types, even though there were Beaufighters in squadron service, proved adequate to the task and, like I stated, had a higher kill to intercept ratio than any other British night fighter in that time period. You are also aware that interception rates in general, regardless of types used were not that high at the time. That had little to do with aircraft type and much to do with inexperience in night fighting techniques in general.


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## yulzari (Aug 29, 2014)

nuuumannn said:


> 24 credited aces scored kills on Defiants in that time.



Just to be a tedious pedant. 

The RAF credited nobody with being an ace. The concept did not exist. The reported performances were given as squadron totals. Whilst each pilot was credited with a personal tally the judgement was upon squadron performances. A Squadron Leader with a modest personal record would be judged effective if his squadron performed well as a whole. Equally a higher scoring Squadron Leader with whose squadron performed less well would be judged as being of lesser quality. For my money it was the gunners who deserved the credit. There was all but no chance of baling out from a Defiant turret, especially under high G forces in a damaged aeroplane.


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## stona (Aug 29, 2014)

Interception rates had more to do with the lack of a good GCI radar system integrated with a useable AI radar on the interceptor than the interceptor itself. Interception rates increased dramatically with the introduction of the earliest and crudest version of the former.

In the period from late 1940 to early 1942 you would have to look at the relative numbers of the British night fighters before drawing any conclusion. The He 219 was a much better night fighter than the Bf 110 but the latter, being far more numerous, was responsible for more bombers in the short period they served together.

Cheers

Steve


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## varsity07840 (Aug 29, 2014)

The turret (night)fighter idea certainly works if the performance of the fighter, and good intercept radar allows it to overtake and engage the enemy from underneath, a tactic that was was proven by German Schrgage Musik equipped JU-88s. Utilizing that tactic, a turret/fixed gun fighter could have been very effective.

Duane


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## nuuumannn (Aug 29, 2014)

> The RAF credited nobody with being an ace. The concept did not exist. The reported performances were given as squadron totals. Whilst each pilot was credited with a personal tally the judgement was upon squadron performances.



I'm aware of this; officially the RAF did not officially promulgate personal tallies, but since the fact, these individuals who scored more than five victories are known as aces within the RAF, even if they weren't officially recognised as such at the time, also, the practice of keeping personal tallies was not actively discouraged within the squadrons, despite the lack of official recognition.



> The turret (night)fighter idea certainly works if the performance of the fighter, and good intercept radar allows it to overtake and engage the enemy from underneath, a tactic that was was proven by German Schrgage Musik equipped JU-88s.



And pioneered by Defiants. Pointing its guns upwards and forwards and approaching the enemy bomber from below and behind was an ideal tactic for night interception by Defiants. The problem that you have identified is the one suffered from the Defiant right from the start; it's biggest weakness was its low forward speed. There are a number of accounts where Defiants sent to intercept Ju 88s were outrun once the bomber got acceleration up. Considering that A.I. radar was in its infancy, these early interceptions were rather remarkable in that almost all of them were made using GCI alone and the eyes of the crew, so the fact that Blenheims and Defiants made interceptions at all is rather surprising. Only one A.I. radar assisted interception was successfully made by a Defiant II, fitted with radar as standard. Although Beaufighters had radar from late 1940, there was much difficulty in maintaining the sets and they frequently malfunctioned, the Beaufighter itself also proved rather a handful for a number of pilots after the Blenheim and Defiant, both being considered easy to fly, but it was, by far a superior product to both types.


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## stona (Aug 30, 2014)

The Schrage-Musik installations were very effective, not least because it enabled the attacker to keep his quarry in sight against the sky whilst remaining unseen himself. 
It may surprise some to know that it did not become a standard, factory fitted, installation on the Bf 110 night fighter until 22nd May 1944. Many night fighters of all types were extensively modified at their units, who seem to have been able to do this unmolested by higher authorities, and oblique firing armament was in more or less limited use for months before this, but it wasn't standard.

The pilots of the Nachtjagd, like their British counterparts who never adopted an oblique firing system, did quite nicely thank you very much with standard forward firing armament for most of the war.
The Ju 88C-6 was produced with a formidable forward firing armament of 3 x MG FF cannons and 3 x MG 17 machine guns. It's only fair to point out that most or all of this was eventually removed on the G-1 because pilots preferred the 2 MG 151/20 cannons of the Schrage Musik installation and complained of being blinded by the muzzle flash of the weapons mounted in the nose (not the ventral tray).

Cheers

Steve


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## fastmongrel (Aug 30, 2014)

Schrage Musik or whatever the RAF called it wasnt a new idea it was a common method of both day and night attack in WWI and the RAF even had several prototypes built where the main cannon armament was set at approx 45 degrees and aimed by a periscope type sight. The muzzle flash would have been fun at night for the pilot.


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## stona (Aug 30, 2014)

I'm not sure I'd call it a 'common' method of attack. It was, as you rightly say, not a new idea and had been toyed with in the past. I'm trying to think of any fighter at the start of WW2 equipped with a fixed upward firing armament, but without success. There may well have been the odd one.

The Luftwaffe adopted an upward firing armament subsequent to their night fighter pilots developing an attack from behind and below very early in the war. It is generally credited to Streib and his comrades in I./NJG 1. It was not an attack profile that came naturally to fighter pilots trained in the standard tactics of daylight interception and by all accounts took some learning. It became almost the standard attack for the Nachtjagd, along with the 'Schrage-Musik' variation later on.

It was on the basis of reports from Streib (and Lent) about the success of the 'from under and behind' attacks that Milch initially turned down requests from some, notably Schoenert, to develop an upward firing armament as early as late 1941. Schoenert rigged up an unofficial system in his Do 17 and this was probably the first WW2 night fighter equipped with what would become 'Schrage-Musik'. 

Three more Do 17s were fitted with an experimental installation in July 1942, this a result of Schoenert badgering Kammhuber directly. Eventually another three were rearmed and were still being field tested by 3./NJG 3 in early 1943.

Meanwhile Schoenert had moved to II./NJG 5 which was Bf 110 equipped. He took his 'special' Do 17 with him and it was at this time that Ofw. Mahle, an armourer serving with that group, saw it and reckoned he could do something similar with a Bf 110. He could, and the first 'Schrage-Musik' equipped Bf 110 was in action, with Schoenert, by May 1943. It would be another year before such an installation became standard on the Bf 110. 

Cheers

Steve


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## Milosh (Aug 30, 2014)

Steve, was the mod to the Bf110 authorized by Mtt and/or the RLM?


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## stona (Aug 30, 2014)

I've got the mod number somewhere, I know its mentioned in Adders night fighter book...somewhere. It would have come from the RLM as the system was tested at its expense on the Do17. I have no idea what input came from the night fighter units which had rigged their own unofficial systems on the Bf 110.
Cheers
Steve


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## Stephan Wilkinson (Sep 1, 2014)

> I am not so sure turret fighters went nowhere. The P-61 seemed to have enjoyed some success.



I'm guessing, without any evidence to back up my musings, that no P-61 ever engaged in combat with the dorsal turret anywhere but locked straight ahead and fired usually by the pilot, though the gunner could certainly have done it as well. I have never read of a combat with the turret displaced or swiveling. Certainly the early buffeting problem was one reason, and though it may have been solved--this remains a question--I have also read that the turret traversed poorly, jerkily.

Anyway, I don't think of the overrated P-61 as a "turret fighter" engaging in aerial combat but as an interceptor that flew pretty much straight ahead and happened to have part of its battery (sometimes) mounted in a fixed dorsal turret. I say it flew "pretty much straight ahead" because that's what you have to do during a night intercept. Hell, I've had a hard enough time keeping track of a simple thunderstorm while turning gently with a radar-equipped Cessna 310, 402 or Shrike Commander. Can't imagine what it would have been like to follow a maneuvering adversary with 1940s radar.

A night fighter had to be a sniper. Whatever it successfully hit never knew it was coming.

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## Koopernic (Sep 1, 2014)

In evaluating the turret fighter it may jet be that the concept was sound but not refined enough and not perfected in terms of technological implementation.

Looking at the Bolton and Paul "Defiant" I would list the following salient points.

1 Adding the Turret and Gunner somewhat slowed the aircraft down. How much is hard to tell as engineering decisions to do with wing sections etc. can
be more decisive here but it was clearly slowed down as the "Defiant" had to have a more draggy glasshouse style canopy.

2 The "Defiant" lacked forward firing armament. I can't imagine that a reasonable armament of say 4 x 0.303 Browning's in the wings would have hurt
performance but it might have allowed the pilots to take the tactical initiative: for instance diving out of the sun into escorting German fighters rather than undertaking a cumbersome and unrealistic manoeuvre to bring their turret to bare. The faster Bf 109 would simply use its superior speed and acceleration to dictate the terms of the engagement. Forward firing guns would have expanded the options for the crew.

3 Technically the gun sight of the Defiant may not have been well developed given the state of the art during the Battle of Britain. Gyro sights can calculate the required lead to hit a target so long as they are tracked accurately and given an accurate range measurement and potentially compensate for air speed and altitude as well. 

A better solution would have been to separate the turret from the sighting mechanism entirely (as done in the B-29/A-26 and proposed in that Wellington with the 40mm gun and predictor) this allows the corrections for lead, fall off to be added in by the predictor rather than offset by the gunner looking through the gyro sight.

It's worth looking at what the Luftwaffe found out about the efficacy of the rear gunner in the Me 110. When engaged in a tight turning fight with the enemy on the Me 110 tail the attacking fighter would tend to fall slightly below the tail of the Me 110 such that the gunner couldn't get the guns onto the adversary. Furthermore because of the violent manoeuvring the gunner had great difficulty in aiming and had absolutely no hope of reloading gun magazines.

The solution in the Me 210/410 was hydraulically operated guns in the cheeks position where they could depress below, with long ammunition belts and a set of 3 gun sights in bug eyes that the gunner could choose to sight a target below and behind. The competing Ar 240/Ar440 had a better setup in my view with highly streamlined low profile ventral and dorsal turret that could be aimed by a periscope, the periscope apparently providing excellent vision, better than viewing throught armour glass.

The "Defiant" certainly had long belt drives and power drive. It might have been improved with a gyro gun sight and some forward firing guns. Ideally the rear turret should have been a remotely controlled barbet with a predictor computer and able to engage targets below somewhat. Technology was barely ready in 1940/41. 

The defect in rear defensive armament, as I see it, is that the attacking fighter usually had about 8 times more fire power and this statistically wins the fight for the fighter. The Defiant wasn't too bad in this regard.

The setup on the P-61 black widow, from a gunnery point of view, was probably excellent. I doubt the aircraft ever had an opportunity to put it to use.

A final addition would have been radar ranging for the predictors. It takes a radar dish of about 10 wavelengths to blind fire guns, with 3cm radar a 30cm/1ft dish is enough. Ranging however can be done with an even smaller dish and as powerful magnetrons operating at around 1-1.5cm were becoming available automatic ranging was possible by the end of the war with dishes less than 10cm. Other factors however, such as jet speed and missiles meant there seems to have been little point in turrets, at least in terms of thinking in the UK and USA. The Soviets persisted with multiple turrets on their bombers.

There were German attempts at turret fighters, the Mockups are shown in the German secret projects series of books. However German attempts at destroying bombers seem to have focused on the Zerstoerer (the name means destroyer, destroyer of bombers) concept (Me 110) with its extra heavy fire power in some cases using outsized guns, up to 50mm, aimed with a predictor equipped with a stereoscopic range finder. The idea faltered also on the vulnerability of the aircraft to escort fighters. (Limiting these sorts of attack was an achievement of the P-38 ) however I believe the attacks could be quite difficult due to the massive turbulence from the bomber stream upsetting the aim of the fighters. This massive turbulence explains to a degree the Luftwaffe preference for developing close in attacks with high calibre low velocity guns.


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## nuuumannn (Sep 1, 2014)

> he "Defiant" certainly had long belt drives and power drive. It might have been improved with a gyro gun sight and some forward firing guns.



Interesting assessment Koopernic, a few points about the Defiant. it's biggest weakness was indeed that it was slow and that was no doubt due to the turret, but it didn't have forward firing armament because the concept of a turret fighter didn't warrant it; it was designed as a bomber destroyer and the idea was that formations of four each were to attack unescorted (note that) bomber formations arriving over britain from Germany. Unescorted because no one told the Brits that the Germans would invade France in 1940 and be able to escort its bombers to Britain. The idea was to get alongside the bombers or below them, using the turret to fire at the bombers from their weak points, like their flanks and bellies.

The problem with arming the Defiant with forward firing guns is twofold. It was slow enough with the turret, if you add forward firing guns, you are adding to its weight, thereby slowing it down even further and you are also reducing its useable fuel load, since the Defiant's fuel was contained in the wings. Therefore, not only would it have been even slower, but it would have no range to speak of.

The Defiant's turret was entirely self contained; the ammunition was contained in two boxes in front of the gunner's legs, which held 600 rpg each and were belt fed. The gunner had a reflector gun sight. The turret was fitted with a switch marked "OFF GUNNER PILOT", but the PILOT selector was more often than not wired off, acting as another off switch. The intention was that the pilot could fire forward, and he had a firing tit on the joystick, but he had no gun sight, also the forward elevation of the guns meant the pilot could not aim true, so it was not used in combat.

A remotely operated turretmight have been a great idea, if the technology was there at the time, but bearing in mind that when the Defiant's turret was being produced, power operated turrets were in their infancy; the first aircraft to be fitted with them had only been in service for a few years. The BP A Mk.2D turret of the Defiant was actually designed in France and was known as the de Boysson turret after its designer. The technology was quite sophisticated and was applied in evert subsequent BP turret. It's operation was by a single stick controller, which was unique at the time; other turrets were more cumbersome.


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## Milosh (Sep 1, 2014)

stona said:


> I've got the mod number somewhere, I know its mentioned in Adders night fighter book...somewhere. It would have come from the RLM as the system was tested at its expense on the Do17. I have no idea what input came from the night fighter units which had rigged their own unofficial systems on the Bf 110.
> Cheers
> Steve



Thank you.


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## nuuumannn (Sep 1, 2014)

Just a bit about the P-61; in Europe and the Med, the P-61s were never fitted with turrets, as these were allocated to fitting to the B-29, which meant that a squadron of gunners that were sent to fly with the night fighter squadrons didn't have a job to do. The problem over Europe was there there weren't very many of them. Here's what Capt Al Jones of the 414th NFS in belgium had to say about the P-61; "I felt that the Black Widow was an extremely honest aircraft, it was very stable and made instrument flying quite easy. The low speed handling qualities were excellent because of the spoilers used for lateral control , and it was also quite good in the high speed regime. This wide range of performance was very desireable in night intruder missions, as the type of aircraft we intercepted ranged from speeds as low as 110 kts all the way up to 350 kts." Despite their technical difficulties, the P-61 was a vast improvement over the P-70s and B-25s that were used as makeshift night fighters before the P-61s arrived. They also had the speed and altitude performance to catch every type of Japanese night intruder that was appearing.


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## GrauGeist (Sep 1, 2014)

There were turreted P-61s in Europe and the MTO. Alot of the P-61s that retained their dorsal turret, kept the turret locked forward to provide additional forward firepower.

Here's a P-61B-15-NO that was photographed over Italy. Sadly, it was lost after the war in an operational accident on 30 October 1945, near Linz-Horsching, Austria.


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## Koopernic (Sep 1, 2014)

What was the purpose of the P-61 turret? It looks like it would have a limited field of fire towards the rear due to the horizontal tailplane, though firing directly to the rear, with virtually no elevation was possible by firing under the tailplane.

Radar aiming of guns was possible towards the end of WW2, though only the US Navy achieved deployment with a sort of wing mounted radar on its corsairs and hellcats. It suggests to me that potentially the P-61 turret could have been aimed by radar though the 9cm versions on the P-61 were barely better than the metric sets on earlier aircraft.


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## GrauGeist (Sep 2, 2014)

The P-61's design was early enough, that it was felt that a defensive turret was necessary. However, by the time it reached operational status, the potential for attack by enemy fighters had become rare.

The original concept for the P-61 called for two turrets, one housed in the nose and one in the rear of the fuselage. Each turret was to have four .50 cal M2 Brownings.


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## nuuumannn (Sep 2, 2014)

Thanks for that Dave. Aha. I found where I went wrong, I should have put that none of the P-61s delivered to the 422nd NFS at Charmy Down had turrets.


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## GrauGeist (Sep 2, 2014)

nuuumannn said:


> Thanks for that Dave. Aha. I found where I went wrong, I should have put that none of the P-61s delivered to the 422nd NFS at Charmy Down had turrets.


No problem!

It is kind of confusing, because of all the types, some were equipped with a turret and some were not. Then, some of the turret equipped types were field modified by either having the turret removed or in some cases, had two of the four M2 MGs removed.

You'll also see in some cases, that an additional fuel cell was installed in the vacant turret well.

Here's a rough breakdown:
P-61A - 300 units.
Early series production: 180 units (all equipped with turret)
Late series production: 120 units (first 37 units with turret - remainder produced without turret option)

P-61B - 450 units.
Early series production: 200 units (produced without turret)
Late series production: 250 units (produced with turret)
_P-61B-11 - 5 units: equipped with two .50 M2 in turret
P-61B-15 - 153 units: equipped with four .50 M2 in turret
P-61B-16 - 6 units: equipped with two .50 M2 in turret
P-61B-20 - 84 units: equipped with new GE turret with four .50 M2_

P-61C - 41 units.
Turret application was a mixture in this series.

P-61D - 2 units.
Produced for high altitude research, no turrets.


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## yulzari (Sep 2, 2014)

The turret fighter concept for the Boulton Paul Defiant had the turret guns, when locked forwards inclined above the airscrew disk, to be used by the pilot in a 'no deflection' mode whereby the drop of the rounds through gravity matched the sight for a given (adjustable) range so the sight merely had to be placed upon the target. This is why the pilot had the facility to fire the turret guns when so locked. No forward firing guns were seen to be needed as they were already there in this mode. Due to a variety of factors aircrews never had the appropriate sights, training, or indeed were made aware, of the intended forward firing method. All that they knew was that they could fire the turret guns when locked forward. When used in the nightfighter role the turret gunner both allowed fire from a variety of directions and gave two pairs of eyes to tell the difference between a Ju88/He111 and a Blenheim/Beaufighter. Also the gunners often had more gun training practice than some of the pilots. What it lacked was a 4x20mm cannon 'one burst, one kill' firepower.Six years previously 4x.303 machine guns were a good fighter weapon set. Six years later 30mm rotary breech HE cannons were pencilled in for new jet designs.


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## stona (Sep 2, 2014)

Hi Milosh.

Mod. T 106. 22 May 1943

It meant that all Bf 110 night fighters leaving the production line or undergoing repair should be built to the following standard.

No GM-1 installation.

MG 17s in upper nose position to be replaced with MG 151/20s with flash suppressors.

MG 151/20s in lower nose to be replaced with MK 108s

MG 81Z in rear cockpit

2 x MG FF/M fitted in oblique firing (schrage musik) installation.

The ventral weapon tray was not to be fitted to aircraft built to this standard.

Cheers

Steve


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## Stephan Wilkinson (Sep 2, 2014)

> The original concept for the P-61 called for two turrets, one housed in the nose and one in the rear of the fuselage. Each turret was to have four .50 cal M2 Brownings.



Not believeable, since the original-original "concept for the P-61" required the nose to be filled not with guns but with the radar dish and ancillary equipment. There never was a P-61 concept that considered ordnance in the nose in place of the radar.


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## GrauGeist (Sep 2, 2014)

Sorry that you have doubts, however the fact of the matter is, the P-61 went through several changes before it became the production series aircraft we are all familiar with.

Some of the changes to the original design were to place the two turrets above and below the fuselage. Then they changed again to placing a single turret atop the fuselage and placing the forward firing weapons (20mm cannon) in the wings. Eventually, they fitted the cannon in the fuselage.

The SCR-720 radar was of course, added and fitted to the nose during these changes.

What an aircraft design starts with is _not always_ what the production aircraft ends up with...


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## vikingBerserker (Sep 2, 2014)

The XP-61E had nose guns in place of radar.


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## nuuumannn (Sep 2, 2014)

> The turret fighter concept for the Boulton Paul Defiant had the turret guns, when locked forwards inclined above the airscrew disk, to be used by the pilot in a 'no deflection' mode whereby the drop of the rounds through gravity matched the sight for a given (adjustable) range so the sight merely had to be placed upon the target.



The thing is, as you mentioned, Yulzari is that the turret guns, when facing forward were not synchronised to the propeller and so the pilot ran the risk of shooting off his own propeller. To prevent the aircraft shooting off its own empennage, the turret had an ingenious mechanism that comprised a rotating drum that spun around at the same speed as the turret, which was driven by an electric motor. The drum had two brushes mounted vertically in it that made contact with slip rings, when the turret turned. These enabled the guns to fire and controlled each bank of guns to enable concentrated fire when the turret traversed past an obstructing part of the aircraft, the top controlled the right and the bottom the left guns. Patterns were cut out of the drum where brushes made contact with the slip rings where the aircraft obstructed the field of fire. This mechanism was fitted to all subsequent BP turrets including those on the Hudson and Halifax and worked quite well.

The Defiant's pilot did not have a gun sight. When trained forward, the turret's guns could not depress below 17 degrees above horizontal. Like I stated earlier, the gunner operated the master switch that controlled the turret and more often than not, the PILOT selection was wired off. Forward and aft of the turret were aerodynamic fairings, which were operated by actator arms worked by compressed air. These retracted automatically when the turret was turned.

Operation of the turret was simple. Once the gunner had strapped himself in and connected himself to the aeroplane; comms, oxy etc, he moved a lever to his left on the table in front of him forward from FREE to ENGAGED. This enabled the turret turning mechanisim to actuate. He would then switch on the sight, then switch on the safety switch from OFF to GUNNER and then switch on the main motor switch located above this to the gunner's right. A red warning light would indicate the system was energised. On the joy stick to his right, a trigger switch actually started the electric motor, which enabled the gunner to move the joy stick from left to right or foward and aft for rotation and elevation respectively. The trigger for firing the guns was a button located on the apex of the joystick and was actuated by pressing with the gunner's right thumb. There was also a high speed button, which enabled the turret to traverse at a faster than normal speed, located directly in front of the gunner on the table. This switched the electric motor on to a faster rpm to enable this, but it did not work for long as the gunner ran the risk of burning out the electric motor. The turret could also be operated manually by a crank handle, with gun elevation being controlled by tilting the gun butts up or down. The guns were mounted on their sides with the cocking handles facing upwards, which enabled the gunner to clear stoppages when required.

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## Stephan Wilkinson (Sep 6, 2014)

> The SCR-720 radar was of course, added and fitted to the nose during these changes.



The SCR-720 was hardly "added." It was the raison d'etre for the P-61 right from the outset. Whether or not somebody postulated putting guns in the nose is irrelevant. It was a dumb idea, and it's unimaginable why any engineer who knew what nightfighting was about would do it is hard to imagine. Any nightfighter crew that fired guns sited five or 10 feet directly in front of them would spend the next 10 minutes flying around like an old man tapping a white cane.

Yes, the XP-61E had guns in the nose, but it wasn't a nightfighter. It was proposed as a long-range escort dayfighter. which was also a dumb idea.


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## wuzak (Sep 6, 2014)

Stephan Wilkinson said:


> Yes, the XP-61E had guns in the nose, but it wasn't a nightfighter. It was proposed as a long-range escort dayfighter. which was also a dumb idea.



IMO the P-61 would have been better if it had been set up like the XP-61E/F-15 Reporter with 2 crew, a bubble canopy, the 4 x 20mm cannon and, of course, the radar in the nose. It certainly would have performed better on the same power.


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## Shortround6 (Sep 6, 2014)

AH yes, but the trouble was that in the initial design stages the British were allowed to have input, sort of a joint specification in the fall of 1940, when the British were still enthralled with the turret fighter idea. 

Of course by the time production examples became available the British had the Mosquito and forgotten (conveniently) about the turret fighter concept leaving the Americans stuck with it 

Perfidious Albion strikes again


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## GrauGeist (Sep 6, 2014)

Shortround6 said:


> Perfidious Albion strikes again




That in fact, is exactly the case. The British Purchasing Commission called for a "twin turret equipped" night fighter. Jack Northrop had started his design when the USAAC called for submissions shortly afterward. Jack abandoned the British request and went after the U.S. Army's request. This is where the P-61's design started evolving.


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## yulzari (Sep 10, 2014)

nuuumannn said:


> the turret guns, when facing forward were not synchronised to the propeller and so the pilot ran the risk of shooting off his own propeller.
> 
> The Defiants pilot did not have a gun sight. When trained forward, the turret's guns could not depress below 17 degrees above horizontal. Like I stated earlier, the gunner operated the master switch that controlled the turret and more often than not, the PILOT selection was wired off.



Quite so Nuuumann. But the turret did have a 'pilot' selection and there was a provision for the pilot to fire the guns when so locked forward. The original concept would have had a pilots gunsight for 'no deflection' firing in this mode (e.g.the cannon armament in the Gloster 9/37) so as to allow the pilot to have fixed forward firing guns using the turret. Certainly the intention was to use the turret mode against unescorted bombers but the impetus to follow the forward firing mode through was not carried forward; possibly due to changes in staff. But the airframe/turret had the hardware. If the pilots had the training and gunsight the crews could have fought the Defiant in both turret and fixed gun modes without the extra weight of fixed guns in the wings.Essentially this was a human management failure, not a concept failure though the paucity of firepower and weight and drag of the turret was always going to make the turret fighter debatable at best.


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## zoomar (Sep 24, 2014)

Back to the late 1930's, I've always wondered why the concept of a high-performance twin-engined fighter with a 4-cannon turret in the nose or immediately above the flight deck was not pursued more seriously by the British than it was. Mounted in this manner the 4 cannon were essentially a trainable nose armament that could be used in turning engagements with other fighters to compensate for the airplane's more limited manuverability. Or was the weight and complexity associated with a power turret just too much to make the concept practical?


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## Shortround6 (Sep 24, 2014)

There were drawings and models made of aircraft with such an arrangement. 

The trouble was that most of the British firms could only handle 2-3 designs at the same time and they were already committed (or over committed) and building a real prototype would have taken too long, several years was the usual estimate.


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## stona (Sep 25, 2014)

Shortround6 said:


> The trouble was that most of the British firms could only handle 2-3 designs at the same time and they were already committed (or over committed)



Most (if not all) the fighter specifications of the mid/late 1930s included the condition that the aircraft should be able to operate by night. Not much consideration was given to a specific, purpose built night fighter. No firm was going to go out on a limb developing something for which there was no clear need.
Was there a night fighter specification issued in the 1930s? The last one I can think of was back in the 1920s, 25/22, which resulted in the Hawker Woodcock. They were probably thinking more of Zeppelins than 200+ mph bombers 
Cheers
Steve


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## nuuumannn (Sep 29, 2014)

> The original concept would have had a pilots gun sight for 'no deflection' firing in this mode



The spec for the Defiant came about as a result of the availability of the de Boysson turret for mass production by BP. Obviously, the pilot could control the guns, Yulzari, or the selector wouldn't have had a PILOT detent, but he did not have a gun sight. My point was that for the reasons stated it wasn't used in practise. 



> I've always wondered why the concept of a high-performance twin-engined fighter with a 4-cannon turret in the nose or immediately above the flight deck was not pursued more seriously by the British than it was.



There was the BP P.92 Boulton Paul P.92 - Wikipedia, the free encyclopedia

One Defiant was fitted experimentally with a turret that mounted a single 20 mm cannon, but it was not put into production, although later in the war BP did build cannon armed turrets for bombers.

Turrets enabled guns to be brought to bear quicker and more accurately than an unpowered gun position. From 1936 almost all bomber specs produced had them; B12/36, which the Stirling was a result of and P13/36, to which the Manchester was built specified powered turrets. At that time though, there were only two powered turret constructors that put powered turrets on aircraft in Britain pre-war, BP and Nash and Thompson, or Fraser Nash. Bristol turrets on Blenheims and Beauforts were not powered, nor were the Armstrong turrets on Ansons and early Whitleys. The Defiant was the design that was chosen for a turret fighter spec; did the British need another? Single seat fixed gun fighters were the major part of Britain's fighter defence; the turret fighter was designed solely for the destruction of enemy bombers.

They did come up with a few uses for turrets; In 1935 only one aircraft had a power operated turret, the BP Overstrand. The first design with a powered turret was the Sunderland, which was the first modern type, i.e. not an obsolescent biplane with fabric covering, like the Overstrand. Within three years, the Whitley IV had a powered tail turret and the Wellington I was fitted with them, but not all had turrets by the outbreak of the war. The Defiant did not enter service until December 1939 and part of the reason why was the usual British delays in prototype to production, but also because the turret took a while to get right for production. A variant of the Lysander was also fitted with a turret, the Delanne Lysander, which had a tail turret, so they were fitting them to what they could. Like I said earlier, the Air Ministry wanted Geoffrey de Havilland's high speed unarmed bomber to be fitted with a tail turret.


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## Shortround6 (Sep 29, 2014)

One of the "almosts" was the Boulton Paul P.92 which was supposed to mount four 20mm guns (+ four .303s?) in a 13 ft diameter low drag turret. It was ordered in prototype form but more urgent work delayed it but not before both a 2/7s scale model for wind tunnel tests and a just over 1/2 size piloted flying model were built.






Wind tunnel tests indicated that with the guns elevated 45 degrees and the turret turned 135 degrees drag increased by about 35% which may be one reason the big turret fighters never made it into the air.


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## yulzari (Sep 29, 2014)

nuuumannn said:


> The spec for the Defiant came about as a result of the availability of the de Boysson turret for mass production by BP. Obviously, the pilot could control the guns, Yulzari, or the selector wouldn't have had a PILOT detent, but he did not have a gun sight. My point was that for the reasons stated it wasn't used in practise.



Forgive me Nuuumann. I should have been more specific. The concept of 'no deflection' aiming is that the round is fired at an angle above the horizontal. As it flies it drops at the same speed as if simply dropped without firing. By estimating the distance to the target the sight can be set to match the fall of the bullet at that distance. In the case of the Defiant they angled above the horizontal was 17 degrees so there was no need to synchronise them to the airscrew as they would pass above the disk.

I certainly agree that there was no such sight fitted but the concept had a certain hold in the Air Ministry in the mid/late 1930's and it was a recognised option for a fixed gun as proposed in the Gloster for example. What appears to have happened is that the impetus died out and the sights were never made, but they were originally pencilled in the Defiant design concept and such gun sight types were trialed. Albeit not in a Defiant. My point is that there was no technical reason why the pilots could not have had such a 'no deflection' sight to use the turret guns fixed forwards at 17 degrees elevation. Had they been fitted and the pilots trained to use them then the option to use the guns as fixed forward firing armament or as a mobile turret would have been available without added weight of extra guns in the wings.

It did not happen and we can only speculate what tactics would have been found best. I suspect that the gunner would have been the user in tackling bombers without close escort and the pilot when dealing with the escorts. The gunner being able to reassert control if the Defiant came under attack from the rear. One reason for the turret was for a gunner to be able to fire a more prolonged burst parallel to the bomber than a pilot closing at speed. The WW1 Bristol F2B Fighter gives an imperfect model of the technique.

This is the reason why there was a function in the Defiant for the pilot to fire the turret guns. A relic of a missed opportunity.

However, as I said above. There was no way a viable one burst one bomber kill firepower was going to be fitted into a viable fighter turret but the Defiant turret firepower matched contemporary fighters at the time it was designed. The Boulton Paul P.92 above shows that this was appreciated and the problems with turrets big enough to hold the necessary weapons. Even that was dwarfed by the 40mm gun turret trialled on the Wellington. Though that was more of a flying anti aircraft battery concept than a bomber hunter.


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## wuzak (Sep 29, 2014)

The Gloster G.39 (F.9/37) was fitted with no allowance guns, in the lower fuselage and in the upper fuselage behind the cockpit.


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## nuuumannn (Sep 30, 2014)

Ahh, thanks for clarifying that, Yulzari; make more sense now and agree with all you say in your last post. I guess in hindsight it is easy to criticise the concept of a turret fighter, but, like you have stated, the tactics made sense when taking into account expectations at the time the specification was being written.


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