Turret Fighters

[nuuumannn]

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.

 

[stona]

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

 

[nuuumannn]

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.

 

[yulzari]

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.

 

[stona]

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

 

[varsity07840]

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

 

[nuuumannn]

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.

 

[stona]

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

 

[fastmongrel]

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.

 

[stona]

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

 

[Milosh]

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

 

[stona]

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

 

[Stephan Wilkinson]

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.

 

[Koopernic]

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.

 

[nuuumannn]

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.

 

[Milosh]

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.

 

[nuuumannn]

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.

 

[GrauGeist]

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.

 

[Koopernic]

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.

 

[GrauGeist]

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.