Did the RAF have designs for a long range escort fighter?

[Shortround6]

The props were fitted by de Havilland teams, travelling across the country, just before the start of the Battle.

I believe that is partially part of the Spitfire 'legend'. There is little doubt that de Havilland teams did travel the country either fitting 'new' props or modifying the 2 pitch props to constant speed. The two pitch prop already had the pitch change mechanism. it needed a governor/control mechanism/system. The Legend rather ignores the The Spitfires and Hurricanes that had been built with Rotol propellers. The de Havilland teams (and squadron mechanics who did most of the conversions after being shown how by the de Havilland teams) did perform a valuable service in bringing large numbers of the older Spitfires (and Hurricanes) up to the newer standard.

There seems to be a bit of confusion as to what was happening when. At least two squadrons (19 and 54) had gotten their hands on a least a few Rotol Spitfires by Dec of 1939 even though the RAE completed a performance report in March of 1940.
The RAE compared a Rotol Spitfire to captured Bf 109 in June of 1940 yet a letter from air vice -marshal H.R. Nicholl on June 16 1940 states that to his understanding no Spitfires on the Supermarine production line had Rotol propellers.
Perhaps Supermarine was using DH props and a shadow factory was using Rotol props?

 

[stona]

.
Perhaps Supermarine was using DH props and a shadow factory was using Rotol props?

What shadow factory in June 1940?

A handful were built by Morris around this time, Castle Bromwich didn't produce a Spitfire until July.

Cheers

Steve

 

[stubbsy]

A very interesting file ref picture. Do you know date were the figures provided, as Leigh-Mallory told Portal, on 14/10/1943, [ref AHB The Planning and Preparation of the Allied Expeditionary Air Force for the Landings in Normandy (Air Ministry) Appendix I/53, Air 41/66 TNA] that the Spitfire IX, modified with the 45 gal tank, would only have a combat range of 230 miles?

The first American trial on their 'Wright Field' modified Spitfire IX achieved ranges of 1365 and 1241 miles at cruise speeds of 264 and 306 mph respectively, on 29 May 1944, see attached

Later anticipated Vickers modified Spitfire ranges (after the American trials but before Dec 1944) are shown here:

 

[Edgar Brooks]

The Legend rather ignores the The Spitfires and Hurricanes that had been built with Rotol propellers.
There seems to be a bit of confusion as to what was happening when. At least two squadrons (19 and 54) had gotten their hands on a least a few Rotol Spitfires by Dec of 1939 even though the RAE completed a performance report in March of 1940.?

I don't know where that came from, but Rotol didn't start manufacturing wooden propeller blades until mid-1940.

The Spitfire was even later, largely because it remained here:-

 

[drgondog]

A very interesting file ref picture. Do you know date were the figures provided, as Leigh-Mallory told Portal, on 14/10/1943, [ref AHB The Planning and Preparation of the Allied Expeditionary Air Force for the Landings in Normandy (Air Ministry) Appendix I/53, Air 41/66 TNA] that the Spitfire IX, modified with the 45 gal tank, would only have a combat range of 230 miles?

The first American trial on their 'Wright Field' modified Spitfire IX achieved ranges of 1365 and 1241 miles at cruise speeds of 264 and 306 mph respectively, on 29 May 1944, see attachedView attachment 281634

Later anticipated Vickers modified Spitfire ranges (after the American trials but before Dec 1944) are shown here:

Combat radius is usually defined by the constraints applied when all external stores are ejected and the aircraft must return solely on the fuel remaining internally. In other words, far less than a straight line, unmolested, ferry flight during which minimal internal fuel is consumed before switching to externals, cruising at best Crusie settings and altitude until the end of the supply is reached.

 

[pbehn]

Really? So the Stirling, Halifax MkI and MkIII and Lancaster MkII had liquid-cooled engines? Who'd've thunked that?!!

As for "weak defensive armament", I'll accept that the .303 was less capable than a 50 cal but human-trained weapons, whether in a power turret or on a swivel mount, aren't the most accurate gunnery platform so the likelihood of a successful "kill" is probably about the same for either weapon. The RAF bomber's primary weakness was the lack of a ventral turret but in overall guns-per-aircraft and the employment method of those guns were about on par, if not ahead, of the US aircraft for much of the war...at least until the deployment of the B-17G.

I discounted the Stirling as it was a sitting duck on night time raids I doubt if the LW would bother doing anything except keeping the box tight to allow ground fire to blow them away. How many of the 7,400 lancs had air cooled engines 350? 400? The Halifax had approx 30% with hercules engines and what does that mean? How do you make a protective formation with so many different aircraft, the only answer is to fly at the speed and altitude of the lowest performer. Add in the loss of speed and altitude of a ventral turret if fitted to some or all and there is no way the British could mount a daylight campaign without crippling losses. The USA took a time out and came back with a new bomber force and escort fighter force.

I accept the technical argument about gun sights, if you accept that the gunner aims and hits a target. In most cases they fire in the general direction and someone gets a lucky hit, in that case the sight doesn't matter it is the effectiveness of the round.

 

[Juha]

ORBs show the early use of the Rotol propellers in Spits and Rotol had begun the large scale production of its CS propellers with magnesium alloy blades in early 1939 according to an article in 23 March 39 Flight magazine.

Juha

 

[Juha]

... In most cases they fire in the general direction and someone gets a lucky hit, in that case the sight doesn't matter it is the effectiveness of the round.

Source for that, please. Gunners were trained to use their sights and aim individual targets. When Me 262s and Me 163s arrived, they were too fast for the gunnery systems of B-17s and -24s and because of that a sector firing system was developed but before that gunners used aimed fire, at least the turret gunners who were fairly well trained to do just that. And with four faster firing mgs one could put more bullets into target area than with two slower firing. That said IMHO in daylight 2 x .5 was more effective than 4 x .303 against aerial targets. The difference during night probably wasn't so clear because normally short firing distances. One good point in the .5 was its long range.


Juha

 

[stona]

One good point in the .5 was its long range.
Juha

Yes but the range of a weapon and the range at which a well trained operator can actually hit anything with it are not the same thing.

Just blazing away in daylight did not work and neither can aircraft carry the amounts of ammunition required to maintain that sort of defence. Experienced Luftwaffe pilots simply used the visible tracer to work out which areas were covered by defensive fire, and presumably avoid them.

At night firing in the general direction of the approaching fighter was often effective. The fighters were looking for a stealthy kill and a bomber that fired at them had obviously seen them. For most night fighter pilots following a corkscrewing bomber, keeping it in sight and manoeuvring into a position to hit it whilst risking return fire was a difficult and dangerous prospect. Far easier to find a less aware target, and there were plenty available in the bomber stream.

Cheers

Steve

 

[Edgar Brooks]

ORBs show the early use of the Rotol propellers in Spits and Rotol had begun the large scale production of its CS propellers with magnesium alloy blades in early 1939 according to an article in 23 March 39 Flight magazine.

Which ones, in particular? In all the ORBs I've read, the propeller never gets a mention, and the only Rotol fitted to (late) Spitfire Is, is the 3-blade 2-pitch Jablo, which wasn't available before 1940.
Some may take the word of the press; I prefer government records:-

 

[Elmas]

And the probability to hit something decrease with distance very, very rapidly....

 

[tomo pauk]

The heavy MG might be better off in hitting something vulnerable, after it punctures the target aircraft skin?

 

[stona]

The heavy MG might be better off in hitting something vulnerable, after it punctures the target aircraft skin?

The problem is hitting the target in the first place. What might or might not subsequently happen isn't the point.

I'd be amazed if the US waist gunners firing over open sights ever hit anything. At least the gunners using computing sights had a chance, up to the limiting range of the sights. I doubt any reliable statistics exist given the level of over claiming by everyone on all sides who had his finger on any kind of trigger.

Cheers

Steve

 

[Mike Williams]

Regarding the constant speed propeller discussion:

Pitch Panic, Flight, 9 December 1943

The Latest Rotol Airscrew, Flight, 23 May 1940

 

[tomo pauk]

Kudos, Mike

Granted, the accuracy of the bomber's return fire was abysmal. Dozens, if not hundreds of guns that might be firing on the interceptor were still a dangerous thing, though.
That prompted various increases in the protection for the Fw-190s (even adding the armored ammo boxes in wings), thus adding the weight to the interceptors. Eventually the Fw-190A-8 lost plenty of performance virtues held by earlier, lighter 190s, thus becoming an even lighter prey to the LR fighters. That is before we even start talking about the 'Sturmbock' examples.

 

[Shortround6]

Which ones, in particular? In all the ORBs I've read, the propeller never gets a mention, and the only Rotol fitted to (late) Spitfire Is, is the 3-blade 2-pitch Jablo, which wasn't available before 1940.
Some may take the word of the press; I prefer government records:-

pages on Mike Williams site:
http://www.spitfireperformance.com/19sqdn-orb-nov39.jpg
Operations record book-No. 19 Squadron collected one Rotol Spitfire Nov 1st. for flying and reliability trials.
http://www.spitfireperformance.com/no54-orb-rotol.jpg
Operations record book-No. 54 Squadron collected 6 Rotol Spitfires on 10/12/39. Three more on 12/12/39. One more on 13/12/39/ and another on 14/12/39.

Spitfire Mk I N.3171 Trials Report
RAE test report of Spitifire I with Rotol propeller, report is dated 19/3/40. Flying was done when?

http://www.wwiiaircraftperformance.org/spitfire-1-me109e-rae-comptrials.jpg
Undated on the page but Mr. Williams is claiming that report is from June of 1940.

Something was going on, perhaps just very small batches? Perhaps Bomber Command was hogging what Rotol propellers there were?
DH had been making constant speed propellers for a number of years. Until the Summer of 1940 they had been being fitted to mainly bombers and a few fighter prototypes. In part this was "policy" as the constant speed "equipment" that could change a 2 pitch prop to constant speed was heavier and more expensive than the two pitch control even though they used the same hub and blades.
DH certainly stepped up and did an amazing job with the conversions but the idea that the idea for constant speed props on fighters came out of the blue needs a little looking at. As does the idea/legend that DH pulled this ALL out of a hat in just 2-3 weeks. Part of the "hat" was a re-allocation of materials and labor from other contracts-projects. The provision of the constant speed units to the fighters was of great importance and perhaps some bombers had to wait a few weeks for propellers until things got straightened out? Apparently (press not government document) some of the machinery from the Gypsy engine line was used to make parts for the conversions.

 

[stona]

Granted, the accuracy of the bomber's return fire was abysmal. Dozens, if not hundreds of guns that might be firing on the interceptor were still a dangerous thing, though.
That prompted various increases in the protection for the Fw-190s (even adding the armored ammo boxes in wings), thus adding the weight to the interceptors. Eventually the Fw-190A-8 lost plenty of performance virtues held by earlier, lighter 190s, thus becoming an even lighter prey to the LR fighters. That is before we even start talking about the 'Sturmbock' examples.

I'm not suggesting that the defensive fire from the bombers was not a concern to the Luftwaffe. Having read many accounts from the men attacking the bombers it obviously was. The issue is range and in excess of around 600m the defensive fire became inaccurate and inefficient. It might have scared or deterred the less experienced attacker and many did open fire at extreme range, but not a determined expert.To be sure of destroying a bomber the attacking fighter would need to close to well within the 600m effective range of the defensive fire and that is why they became more and more heavily armoured and why the Luftwaffe attempted the development and installation of ever more long ranged weapon systems.

There is a well known reel of gun camera footage from the 'Schiesschule der Luftwaffe' compiled in July 1944 showing numerous attacks. In all the beam, quarter, rear or rear and under attacks the fighter breaks off ('abgang' on the captions) at between 400m and 50m. Somewhere around 200m is about the normal, well within the effective range of the bomber's defensive fire.

Cheers

Steve

 

[pbehn]

Source for that, please. Gunners were trained to use their sights and aim individual targets. When Me 262s and Me 163s arrived, they were too fast for the gunnery systems of B-17s and -24s and because of that a sector firing system was developed but before that gunners used aimed fire, at least the turret gunners who were fairly well trained to do just that. And with four faster firing mgs one could put more bullets into target area than with two slower firing. That said IMHO in daylight 2 x .5 was more effective than 4 x .303 against aerial targets. The difference during night probably wasn't so clear because normally short firing distances. One good point in the .5 was its long range.


Juha

I have several sources, the first is other posts on this thread, second is the historical need for an escort, third is the statistics of guns and bomber escort. You can read the other posts and the historical need of an escort for WW2 daylight bombers is a "given".

on point 3
consider a marksman with a rifle, to hit, at 600 yards, a man on a horse (man or horse) with a rifle without a telescopic sight would be a fantastic shot. To hit the same man on a galloping horse would be unbelievable. Now put the marksman on a vibrating platform moving in all directions by small amounts and change the man on the horse for an aircraft which relative to the marksman can be doing zero MPH or 600 MPH (200 MPH bomber speed and 400 mph fighter speed in opposite directions) and also it can move in any direction. Additionally in a dorsal or ventral turret the wind speed varies from approximately 200mph head wind, tail wind, side wind and the effect of gravity varies from maximum in a horizontal shot to zero on a vertical shot. The use of a machine gun instead of a rifle is to compensate for inaccuracy, a sniper always uses a single shot rifle.

It is commonly said that a fighter attacking a box of B17s faced a minimum of 100 guns. Those guns were firing a minimum of 10 round per second. If 1000 rounds per second were targeted with anything like accuracy then an escort would not be required. Not to take away from the bravery and courage of the guys who did the business and bought our freedom with their lives but the fact is the gun systems just threw bullets in a general direction. If you consider the speeds involved the aiming and traversing systems used then the defence amounts to little better than early bombing at night or through cloud. The firepower of a bomber box was in theory enough to provide almost complete protection but in practice it wasn't, because the defensive guns could not be brought to bear with anything like the accuracy required.

 

[Juha]

Hello pbehn
so you don't have sources to back up your claim. The need of an escort rose from the inherent advantages of fighters over bombers but that is a different thing than your claim that the gunners didn't aim to individual attacker. And why the LW adopted the more difficult head on attack over the tradiotional stern attack after first contacts with B-17 formations? Why they shunned down individual attacks against the USAAF heavybomber formations and went to formation head-on attacks? If 10 or 25 fighters attacked line abreast there weren't 100 mgs firing at each of them.

 

[rank amateur]

Gentleman, allow me to compliment each and everyone of you about the quality of this thread. There is enough good stuff here to inspire 3 books I would love to purchase.

Chrzzzz