An Allison V-1710 with a two-speed supercharger in 1942 (3 Viewers)

[Engineman]

The concept for the Germans with their long-range Fighters at the 1939 start of WW2 going forward to the mid-1940 BoB, was the Bf 110 twin-engine Fighter. The 110 proved to be unable to survive in the face of the Spitfire attacks, despite the very good performance of the 110. The Germans had to support bombers with the short range Bf 109, although they quickly introduced the drop-tank for the 109 after the BoB. The Germans were forced to adopt unescorted night-bombing of the UK after September 1940 to reduce the escorted day-bomber losses.
The P-51B onwards introduced an efficient combination of good aerodynamic performance and good all-altitude engine performance, with sufficient total fuel, including drop tanks, for a very-large escort and combat range. Although the heavier weight of the P-51B reduced rate of climb performance relative to the German fighters, the P-51B high speed capability and good handling allowed the P-51B escorts to effectively control the fighting with German single engined fighters. Additionally, it would seem that sufficient Allied escort fighters were eventually employed to counter most of the attacking German fighters during daylight raids. Also, the German Fighter force suffered with reduced fighter-pilot training and experience.
The German commanders were amazed by the 2-Stage Merlin engine that they began to see in 1942, and equally amazed by the performance in role of the P-51B as an escort fighter when it developed its long-range capability.

Eng

 

[drgondog]

The tactics used by the RAF were dictated by the short range of the fighters, the short range was a result of lack of engine power, as engine power increased along came the ability to carry more weight in guns, ammunition or fuel so the use of fighter tactics should have moved with it.

The Mustang I had the same engine power as the Spit V but far more range. The Mustang I was not comparable to the Spit V as a point interceptor, but was quickly adaptable to the same engine integrated into the Mark IX. The resultant Mark X/Mustang III Still faster than the Spit IX at all altitudes, would have been comparable to the Spit V as a point interceptor, but vastly more range.

The reason (rational) that RAF declined to add more fuel to extend tactical radius, was that there were other aircraft (available) that were better suited for roles that may have overlapped the Spit IX/XIV 'super' with more fuel and bomb racks.

The weight comparison between the Spit IX and the P-51B resulted in favoring the Spit IX by 1,480 pounds (5,559 vs 7,039) sans armament but all fixed equipment, for Empty Weight. Before an ounce of fuel was added but the significant differences were the wing group (255lbs), the Landing Gear (322lbs), Fuel tanks (214lbs), prop (156lbs), Cooling system (184lbs), Oil supply system (207lbs).

Part of the reason was the difference in design limit load of 7.5G AoA loads vs 8G for Mustang. When you are forced to account for greater weight in the wings due to vast difference in fuel supply the weight penalty to account for was beyond the weight of fuel/oil for longer range.

By contrast the XP-51F compared to Spit IX was 91lbs (2,258lbs vs 2,167lbs) for Wing, fuselage, empennage, main gear, engine mount. The Bare Weight difference before Fixed Equipment was 174lbs (5,203lbs vs 5,029lbs). That said the P-51F fully loaded internally (180-gal fuel, 12-gal oil, 1000 rnd 50 cal) for a long range escort mission, sans drop tanks but 180-gal fuel, was 8,117lbs. ROC with the 1650-9 engine (same as P-51H and equivalent to Merlin 100) was 6,550fpm at SL, 4,720fpm at 20,000ft, 2,640fpm at 30,000ft.

The combat radius with 2x75-gal tanks and 180-gal internal fuel was 790 miles with 20 minutes combat, average cruise speed of 344mph and dropping external fuel tanks with 7-gal in each tank. The latter to reserve 30 minutes loiter at the end of the mission.

But it could NOT add a fuselage tank and still fly due to impossible aft CG issue, worse than the P-51B/D.

The point (finally) is that 'simply adding more fuel', ain't simple and far beyond finding a location for the addition.

The P-47D-25 had to be re-designed from firewall to pilot's seat to add 65-gal to main fuel tank. A P-47D-4 was tested with 75-gal aft of the seat and deemed dangerously unstable. All in it took six months for a prototype demonstration in November 1943. It took NAA and Lockheed two weeks to add and test the 90-gal steel fuselage tanks in the P-51B and add the two 55-gal LE tanks for the P-38J in July 1943.

The P-47N had a 13" plug inserted outboard of landing gear to add the 2 extra 93-gal wing tanks.

So, you be the designer - tell me how you add 80-gal to the Spit IX to match the XP-51F, or 170-gal to match the P-51B? And remember, it still needs to retain superb handling qualities as well as pull out of a dive with both wings attached?

 

[yulzari]

The tactics used by the RAF were dictated by the short range of the fighters, the short range was a result of lack of engine power, as engine power increased along came the ability to carry more weight in guns, ammunition or fuel so the use of fighter tactics should have moved with it.

Not just that. RAF tactics were built pre war around engines of @1,000bhp and two blade fixed pitch propellors and short grass fields. By the start of the war those grass fields were often in France and even shorter and rougher. Hence sending Gladiators initially until improvements allowed the same to be used by Hurricanes. By the start of 1941 we are looking at routine power @50% more, three blade propellors and constant speed propellors and more often concrete runways. However they had to carry armour, self sealing fuel tanks and a heavier armament etc. so that cut into the use of the extra power. Strategically the fear of invasion of the home islands was very real and remained so until the Soviets brought the Germans to a halt and could begin to push back in 1942*. All of this left the fighters fixed in a base position of being defensive interceptors and the best being kept at home. The Mediterranean and especially East Africa and the Middle East, working on a shoestring and the Far East operationally sacrificed. The 1941 forward fighter operations over the Channel coast had to do so with pure interceptors if they were to maintain their prime rôle of defence of the home islands. By 1943 the situation had changed completely and Spitfires were free to be passed to arm the USAAF in quantity at home and the Mediterranean. We can see these phases with hindsight, but their progress was not so obvious at the time and there was an understandable lag between the situation changing, through it's recognition to accommodation and any design and/or production changes entering meaningful service.

*American readers may have to adjust their understanding of the decisions made under the perceived, and real, situation.

The home islands were the only place where the war could be lost and they were literally within ground eyesight of the enemy and within actual heavy artillery range and coastal motor boat range. With the valuable aid of the Commonwealth and US arms purchases Commonwealth forces relied above all upon the freedom of the home islands and even the most vigorous offensive actions against the enemy were severe nuisances at best. Given the need to control the seas for imports and the intercontinental logistics from the North Sea to all but circumnavigate Africa it was remarkable how much was done in 1941 to hold off and sometimes defeat the Italian army in North Africa who had a very short logistical distance to sail within range of their own land based fighters and totally defeat the Italians in East Africa using far inferior scraped together forces, put down rebellion in Iraq, again with far inferior forces and engage and defeat France taking Syria and Lebanon. Defending Egypt whilst sending an expeditionary force to Greece all whilst having lost a continental war in France and Belgium and in Norway. It was not, in the eyes of the time, a given that Britain would remain able to continue to conduct a war or even remain free. It is easy today to say that they should have done certain things to enable better offensive operations but the hazard of losing the home islands was so great, whatever the actual risk, that it had to override all. That they could take brave risks was demonstrated by sending a whole armoured division by sea from Britain all the way around Africa in 1940 when a fear invasion of Britain was at it's height given the extreme paucity of armour at all at home. The voyage taking so long that it did not arrive until 1941. Á time when obsolete biplane bombers and fighters were still in significant use in the region. Vickers Valentia, Hawker Hart variants, Hawker Fury, Gloster Gauntlet, Vickers Vildebeest etc. The army was still using cavalry regiments in Syria in 1941 and making arrangements to use whatever it had which was not in Egypt to defend Syria and Iraq from potential German advances from the Caucasus south into the Middle East.

They were desperate times when my home city lost it's entire city centre to bombs and fire and Rolls Royce armoured cars were still in use abroad and my fellow Yeomanry were at war in Syria with their horses, swords and pre Great War Hotchkiss Portable machine guns and my grandfather's fellow platoon Home Guards were sitting behind their Vickers machine guns in bunkers overlooking the beaches of their coastal village on the North Sea, loopholing their houses and mining the approach roads and road bridge. His fellows were ex Great War or even South African War veterans who knew there was no withdrawal possible and their rôle was not to defeat the enemy but merely delay him for a short while.

To reiterate my introduction, the RAF, deliberately and necessarily, prioritised the fighter defence of Britain itself which meant that they prized the rôle of their fighters as interceptors above all. Whether they chose well or carried it out well is another matter. They wanted interceptors above all.
American fighters had a different context. The sheer size of the United States and the likely use of its forces as an expeditionary force required that they had a far greater range.
Different answers to different questions. The respective operational requirements that resulted in the aeroplanes were both quite specific in this matter.

 

[Steamed_Banana]

As usual with these discussions, we are focusing a lot here on BoB and then 8th AF long range escort / strategic bombing.

But most of the war was fought in between these two events. Spitfire I and II and early V were great as interceptors for the BoB. Mustang III and later was phenomenal for the long range escort role in 1944. But there was a lot of fighting that took place between these two major poles of the air war, that tends to always be glossed over or treated as secondary in importance, when in fact this was where the war was really decided - in the very difficult fighting from 1941 through 1943.

The Spitfire V was one of the most important weapons in the Allied arsenal during this era. It continued to be one of the best, if not the best counter to the top Axis fighters, but as we know it struggled for a while against the Bf 109F, the MC 202, and the Fw 190. Here one of the biggest problems was range, and another significant issue was low altitude performance. It was brought into the Pacific and the CBI, and here too it had problems, mainly related to range and endurance. The debacle at Darwin was in substantial part due to the limited fuel capacity of the Spit V. This also prevented Spitfires from being used in the island campaigns and in New Guinea. They had similar problems in Burma, and in addition, found that performance advantage over the Ki-43 diminished a great deal at low altitude.

The Spit V didn't need the spectacular range of a Mustang III or IV, but it needed the middling range that a P-40, Wildcat, Hellcat, early P-38, early Thunderbolt, or the late arriving but very welcome Spitfire Mk VIII.

The Spit V seemed to have been deemed 'good enough' with a lot of effort put into the Hawker fighters trying to catch them up, giving the Merlin XX to the Hurricane and putting all that work into the Typhoon. But there were several middling improvements which I think could have really helped if they had been introduced earlier:

• More internal fuel - was there anything to stop them adding the leading edge wing tanks or larger fuselage tanks of the Spit VIII to the V?
• Better external fuel tank support - not just for 'slipper' tanks but for less draggy / streamlined external tanks like most other fighters had
• More power at low altitidue (without sacrificing medium - high altitude performance) - Pertinent to the thread topic, this I think would have been covered by the Merlin XX or equivalent
• Better Tropical filter system much earlier - Aboukir type was a major improvement, but it should have arrived much sooner.
• Bendix carburator - This is another baffling delay which really helped in combat once it was added
• Metal control surfaces - another big improvement to combat capability (esp. roll rate at high speed) I'm not certain of the timeline for these
• Clipped wings - this was another big help for roll and low altitude performance which probably should have been introduced earlier. The nice thing about the clipped wings is that it was an easy modification which could be reversed if needed, so it could be available depending on the Theater. But this would have been helpful both in the Med and the CBI

 

[Steamed_Banana]

To reiterate my introduction, the RAF deliberately and necessarily, prioritised the fighter defence of Britain itself which meant that they prized the rôle of their fighters as interceptors above all. Whether they chose well or carried it out well is another matter. They wanted interceptors above all.
American fighters had a different context. The sheer size of the United States and the likely use of its forces as an expeditionary force required that they had a far greater range.
Different answers to different questions. The respective operational requirements that resulted in the aeroplanes were both quite specific in this matter.

This all makes sense especially for the very early war. And as I stated upthread a bit, I don't think most here are interested in second-guessing the planners of 1941 - 1942 in the sense of condemning their mistakes, but rather to think through what could have been done with the benefit of hindisght.

To wit, and per the OP, I don't think putting Merlin XX in a Spit V would have hurt it's capabilities as an interceptor, to the contrary I would expect better low altitude power would improve time to altitude, while also giving it some extra capability against Fw 190s which were a threat on the home front as much as in the Med, if not more so.

 

[Shortround6]

As usual with these discussions, we are focusing a lot here on BoB and then 8th AF long range escort / strategic bombing.

But most of the war was fought in between these two events. Spitfire I and II and early V were great as interceptors for the BoB. Mustang III and later was phenomenal for the long range escort role in 1944. But there was a lot of fighting that took place between these two major poles of the air war, that tends to always be glossed over or treated as secondary in importance, when in fact this was where the war was really decided - in the very difficult fighting from 1941 through 1943.

I agree with this, there is sometimes too much emphasis on the BoB.

The Spitfire V was one of the most important weapons in the Allied arsenal during this era. It continued to be one of the best, if not the best counter to the top Axis fighters, but as we know it struggled for a while against the Bf 109F, the MC 202, and the Fw 190. Here one of the biggest problems was range, and another significant issue was low altitude performance. It was brought into the Pacific and the CBI, and here too it had problems, mainly related to range and endurance. The debacle at Darwin was in substantial part due to the limited fuel capacity of the Spit V. This also prevented Spitfires from being used in the island campaigns and in New Guinea. They had similar problems in Burma, and in addition, found that performance advantage over the Ki-43 diminished a great deal at low altitude.

We also tend to forget that both the Spitfire I and V had long production runs. The MK I was over 2 years and there were a lot of differences between a June 1938 MK 1 and a June 1940 MK I. Same for the MK Vs.
The Spitfire is also the poster child for what better fuel could do. With the aid of the Hooker single speed supercharger a 1942-43 Spitfire had around 50% more power than a 1938 Spitfire. A Merlin 45 running 12lbs of boost had about 1/3 more take-off power than a MK I Spitfire had and almost double what a fixed Pitch Spitfire MK I had. Figure planned climb times accordingly for 1938-39.
The MK V Spits didn't higher boost limits perhaps as soon as they should have?

The Spit V didn't need the spectacular range of a Mustang III or IV, but it needed the middling range that a P-40, Wildcat, Hellcat, early P-38, early Thunderbolt, or the late arriving but very welcome Spitfire Mk VIII.

It is easy to criticize the Spitfire here but let's remember that many of the early US planes took a 20-33% reduction in internal fuel when they went to protected tanks. Some planes got it back quicker than others. However, the British didn't extend the range of their 2nd generation fighter very much. Typhoon carried 154 Imp Gal (185 US) internal to feed the Sabre engine so range/radius sucked. It also took 32 Imp gal to take off and climb to 15,000ft.
Hellcat doesn't show up until late 1943.
But yes, adding another 10-15 gal inside and 40 gal tank outside (imp gal) could have equaled at least the P-39

The Spit V seemed to have been deemed 'good enough' with a lot of effort put into the Hawker fighters trying to catch them up, giving the Merlin XX to the Hurricane and putting all that work into the Typhoon. But there were several middling improvements which I think could have really helped if they had been introduced earlier:

• More internal fuel - was there anything to stop them adding the leading edge wing tanks or larger fuselage tanks of the Spit VIII to the V?
• Better external fuel tank support - not just for 'slipper' tanks but for less draggy / streamlined external tanks like most other fighters had
• More power at low altitidue (without sacrificing medium - high altitude performance) - Pertinent to the thread topic, this I think would have been covered by the Merlin XX or equivalent
• Better Tropical filter system much earlier - Aboukir type was a major improvement, but it should have arrived much sooner.
• Bendix carburator - This is another baffling delay which really helped in combat once it was added
• Metal control surfaces - another big improvement to combat capability (esp. roll rate at high speed) I'm not certain of the timeline for these
• Clipped wings - this was another big help for roll and low altitude performance which probably should have been introduced earlier. The nice thing about the clipped wings is that it was an easy modification which could be reversed if needed, so it could be available depending on the Theater. But this would have been helpful both in the Med and the CBI

I am not sure when the 30 gal and 45 gal tanks showed up. I believe at least the 30 gal tanks were combat rated. This is confusing as they were making both tanks in a variety of materials including wood. The 30 gal tank/s may have been low drag, not a lot of good information

In hindsight the Merlin 45 could have allowed to use 12lbs of boost earlier instead of 9lbs, not a good as using low gear but it could have made up some of the difference.

Metal control surfaces gets tricky, what we know now vs what they knew then. First P-47s used fabric covered control surfaces but they stopped that in the first part of 1942.
F4Us used fabric covered outer wings. Spitfires went through 2 different stages. metal alerions first, metal elevators much later.

Agree on the clipped wings.

 

[Steamed_Banana]

I agree with this, there is sometimes too much emphasis on the BoB.

And the Strategic Bombing campaign, IMO. The Mustang III and later was a magnificent fighter but it wasn't available for much of the war.

We also tend to forget that both the Spitfire I and V had long production runs. The MK I was over 2 years and there were a lot of differences between a June 1938 MK 1 and a June 1940 MK I. Same for the MK Vs.
The Spitfire is also the poster child for what better fuel could do. With the aid of the Hooker single speed supercharger a 1942-43 Spitfire had around 50% more power than a 1938 Spitfire. A Merlin 45 running 12lbs of boost had about 1/3 more take-off power than a MK I Spitfire had and almost double what a fixed Pitch Spitfire MK I had. Figure planned climb times accordingly for 1938-39.
The MK V Spits didn't higher boost limits perhaps as soon as they should have?

Yes agreed, and good point about the boost limits, that's another point to add to the list. Although apparently that may not have been as feasible in the tropics. The Australians were apparently limiting them to +9 boost for reasons of overheating. Cooling for the tropical environments also seems to have been an issue but I'm not sure how to address it especially since it also coincided with the need to filter heavily for dust.

A lot of the improvements I was listing for Spit V were eventually implemented on Spit V, it just took a long time.

It is easy to criticize the Spitfire here but let's remember that many of the early US planes took a 20-33% reduction in internal fuel when they went to protected tanks. Some planes got it back quicker than others. However, the British didn't extend the range of their 2nd generation fighter very much. Typhoon carried 154 Imp Gal (185 US) internal to feed the Sabre engine so range/radius sucked. It also took 32 Imp gal to take off and climb to 15,000ft.
Hellcat doesn't show up until late 1943.
But yes, adding another 10-15 gal inside and 40 gal tank outside (imp gal) could have equaled at least the P-39

Is there any reason why they couldn't have added the fuel capacity of the Spit VIII to the V or IX?

I am not sure when the 30 gal and 45 gal tanks showed up. I believe at least the 30 gal tanks were combat rated. This is confusing as they were making both tanks in a variety of materials including wood. The 30 gal tank/s may have been low drag, not a lot of good information

In hindsight the Merlin 45 could have allowed to use 12lbs of boost earlier instead of 9lbs, not a good as using low gear but it could have made up some of the difference.

Metal control surfaces gets tricky, what we know now vs what they knew then. First P-47s used fabric covered control surfaces but they stopped that in the first part of 1942.
F4Us used fabric covered outer wings. Spitfires went through 2 different stages. metal alerions first, metal elevators much later.

yeah I was reading that. I'm not sure how fast and how thoroughly this was introduced.

Agree on the clipped wings.

This one is also baffling seeing as the capability was built in, or was I wrong about that? When were the outer wing-tips bolted on and removable?

 

[Shortround6]

To reiterate my introduction, the RAF deliberately and necessarily, prioritised the fighter defence of Britain itself which meant that they prized the rôle of their fighters as interceptors above all. Whether they chose well or carried it out well is another matter. They wanted interceptors above all.
American fighters had a different context. The sheer size of the United States and the likely use of its forces as an expeditionary force required that they had a far greater range.
Different answers to different questions. The respective operational requirements that resulted in the aeroplanes were both quite specific in this matter.

To wit, and per the OP, I don't think putting Merlin XX in a Spit V would have hurt it's capabilities as an interceptor, to the contrary I would expect better low altitude power would improve time to altitude, while also giving it some extra capability against Fw 190s which were a threat on the home front as much as in the Med, if not more so.

We are also blending in several years here so the answer/s are not as straight forward.
Spitfire climb times.
altituide.........................................20K ft...........................30K ft
Early Merlin fixed prop..............9.4................................22.4
Merlin III C.S. prop......................7.7................................16.4
Merlin XII C.S. Prop.....................7.0...............................13.7
Merlin 45 9lbs boost..................7.1...............................12.9
For context
P-40B...............................................7.9................................20.3

The last 2 Spits are using 2850rpm and 30 minute boost rating.
Please note that the two pitch prop helped getting off the ground, it didn't help climb very much.
P-40 used a CS prop with more pitch range but used combat (military) power for the first 5 minutes and lower power than the Merlins (2600rpm) for the remainder of climb.
P-40B was tested at 6835lbs which included 120 US gal (100 imp gal) of fuel.

How important was time to climb in which year?
How important was range in which year?
What fuel was available in which year? Huge difference from 1939 to early 1942.

Bf 109F really screwed things up for the British. The improved aerodynamics added over 20mph to speed over the 109E-3/4 using the same engine. Except they used a better engine in production models in 1941. The Hurricane II was supposed to combat the 109E even if it got a slightly better engine (think Merlin XII in Spitfire type improvement) but the improved aerodynamics and the DB 601E combination killed any hope of the Hurricane staying competitive. The 109F with 601N was bad enough. But this was NOT known in the summer and fall of 1940 when the decision to use the Merlin XX in the Hurricane was made. The Spits were getting the Merlin XII engines anyway (slowly).
A big question (for me anyway) is when was the Merlin 45 was OKed for 12lbs of boost? And what were the performance gains.
We know that when 16lbs of boost was used the Spitfire V gained about 1100fpm of climb below 8,800ft and then tapered off to the 9lb climb rate the further it climbed.
We also know that the 16lb rating was good for about 35 mph in speed up to about 13,000ft and fades to no improvement over 19,000ft.

 

[Steamed_Banana]

The +16lb rating may not have mattered at altitude but it really helped at middling alt and down low, and one thing people need to keep in mind in general, is that WW2 fighters could generally get from high altitude down to low very quickly compared to going in the other direction. In fact diving to pick up speed can be a good way to get back up to altitude (via zoom) in another place, especially useful when you find yourself in a pickle wherever you started from.

I believe this is what in part gave the Spit V legs later on in the Med, into 1943, and was also one of the secrets for survival of the P-40s, because once they dropped down below 10,000 ft they actually gained a performance advantage over most marks of the Bf 109F and G.

What made this more viable for Spitfires in general was adding the bendix carb which enabled the quick escape maneuver to get into that fast dive in crucial fewer number of seconds than before. The improved roll rate helped too of course. It also somewhat negated the escape maneuver (i.e. via zero G nose-over) that the German pilots had been relying on since the Battle of Britain.

 

[Shortround6]

The Australians were apparently limiting them to +9 boost for reasons of overheating.

The Australians seem to have gotten Merlin 46 engines (mostly?) with larger impellers. This helped altitude performance but hurt take-off and climb, If allowed to use 12lbs for take-off the Merlin 46 had 85 less HP than a normal Merlin 45. Running at 9lbs would have shown a similar but slightly smaller difference and at 2850rpm and 9lb climb limit would have also showed a similar difference until the planes got into the high teens. The larger impellers may have heated the air a bit more at the rpm settings.

Is there any reason why they couldn't have added the fuel capacity of the Spit VIII to the V or IX?

Wing fuel tanks for Spitfire VIII

question is if they fit in-between two ribs or if the noses of one or more ribs have to be cutaway or modified?
One excuse was they didn't want to retool the factories than were making the wings. I cannot make a judgement on that one way or another. How much production disruption could be tolerated? Obviously, it could be done and was done but only in a few factories.

This one is also baffling seeing as the capability was built in, or was I wrong about that? When were the outer wing-tips bolted on and removable?

It seems to have been done quite easily and there is a least one picture of a Spitfire in transit on a carrier deck with the wing tips in the cockpit to reduce wingspan, There may have been fairings/covers bolted on the wing ends to protect them in transit.

 

[tomo pauk]

question is if they fit in-between two ribs or if the noses of one or more ribs have to be cutaway or modified?

The two neighboring small ribs were removed, and the additional skinning was added to cater for the lost rigidity.

 

[tomo pauk]

What made this more viable for Spitfires in general was adding the bendix carb which enabled the quick escape maneuver to get into that fast dive in crucial fewer number of seconds than before. The improved roll rate helped too of course. It also somewhat negated the escape maneuver (i.e. via zero G nose-over) that the German pilots had been relying on since the Battle of Britain.

The 'fuel pump' carb was tested on the Spit V and found to add 8-10 mph and 1500 to the celing.
link
I don't know whether the Spit Vs were actually retrofitted with the better carbs in 1943-44.

 

[Shortround6]

Thank you. Adding in the fuel lines may have increase the workload.

 

[Shortround6]

What made this more viable for Spitfires in general was adding the bendix carb which enabled the quick escape maneuver to get into that fast dive in crucial fewer number of seconds than before.

Miss Shilling had worked out at least a partial solution in the winter of 1940/41 and by the end of March 1941 most in service Spitfires had been modified and the cutting out problem was largely solved. It did not allow prolonged inverted flight, but the German tactic of "bunting" was largely solved.

 

[Geoffrey Sinclair]

As expected RAF fighter policy kept evolving during WWII, engine availability and what they could be fitted to meant by mid war it was Spitfire for high altitude, Hurricane/Typhoon then Tempest for low to medium altitude. The final ideas were for an up to 20,000 feet piston fighter (Fury/Sea Fury) with jets for above 20,000 feet.

Hurricane production, only Hawker built IIC, IID, IV and V.
Hawker Brooklands, site constrained by urban growth, phased out of production Q3/42
Hawker Langley, the new Hawker site, Q4/39 until end of production in July 1944. The occasional Typhoon 1941 to 1943 (5 Ia, 10 Ib), first 3 Tempest in October 1943, then from January 1944.
Gloster, Q4/39, to March 1942, Typhoon production started in June 1941, Meteor in February 1944, Hurricane 1,850 I, 33 IIA, 867 IIB, made up of 500 off a 1938 Hawker contract, 100 direct order in 1939, rest ordered in 1940.
Austin see below

Canadian Car And Foundry
The quarterly reports and schedules also give the total number of aircraft under order, from eight hundred, all for the RAF, at the end of June 1941, to one thousand two hundred at the end of February 1942, including four hundred for export ordered in the third quarter of 1941, to one thousand four hundred and fifty including four hundred for the RCAF at the end of March 1942, after a further two hundred and fifty more for the RAF were ordered. Build order 949 RAF+1 NEI, 375 RCAF, 101 RAF, 25 RCAF. The 1 in 1,451 was a prototype for a Netherlands East Indies order, flying around Q1/1942. Line converted to build Lancaster, last Hurricane in May 1943, first Lancaster in August, double figures reached in March 1944.

On 27 August 1941 Canada ordered 400 Hurricanes, 100 for the Netherlands East Indies, 300 for China, this changed to 72 for the Netherlands East Indies, 328 for the USSR, to use Merlin 28 and US built propellers and shipped across the Pacific. By the time production started it was 400 RCAF, in 1943 it became 250 RCAF and 150 RAF, the 150 giving rise to the claim of the mark XI (Merlin 28 RCAF equipment), these 150 PJ serial airframes were stripped so as to be the same standard as mark II production. The CCF line output expanded to 50 to 70 a month in early 1941, down to 11 in August, none in September, 1 in October before returning to previous output.

If converting a Hurricane factory to Spitfire was simple enough despite the different construction methods, then converting Bell to P-40 or P-51 production should be simpler, or Curtiss to P-47 or P-51. And the US, with much more ability to do such a change noted how long it would take and how much it would cost.

By the way orders for several hundred Tornado were placed with Gloster, Avro and Cunliffe-Owen in 1939 and 1940, the failure of the Vulture was another hole in early war British fighter production.

Austin contracts, small factory, production peak of around 30 a month 1941 to 1945.
863 Battle in 1936
100 Battle in 1939
300 Battle in 1940 (244 cancelled)
Final 266 built as Target Tow

420 Stirling in 1939, extended by 200 in 1942, built as 191 I and 429 III from March 1941 to October 1944, monthly production reached double figures in February 1942.

300 Hurricane IIB in 1940, production from February 1941, only 15 by end August, up to 30 a month in January 1942, ending with 2 in October. Think emergency order.

365 Horsa I components in 1941, fuselage centre sections. Order officially built June 1942 to around February 1943.

Lancaster ordered in 1942, after end war cancellations built as 150 Lancaster I and 180 VII March 1944 to December 1945, again a slow start, double figures reached in September 1944.

Spitfire fuel tanks, after removing the idea of wing fuel tanks in order to carry heavier armament the Spitfire I carried 85 gallons, no one expected bolting a 50% more powerful engine onto it. The VII/VII was the second attempt after the III to update/change the airframe The redesigned VII upped front fuselage capacity to 96 gallons plus 2x12.5 gallon wing tanks, the VIII made the wing tanks 14 gallon, total 124 gallons. This became the airframe for the mark XIV. The Spitfire VIII range is quoted at 660 miles, the IX at 434 miles, which is economic cruise less a deduction for getting to combat height, 39 gallons gives 226 miles. Fast cruise 66 gallons gives 320 miles. What is being escorted using what tactics? The Spitfire was a minority player in the Middle East from its arrival to end 1942 and mostly air superiority. The RAAF decided at 190 or 200 mph TAS at 15,000 feet with 20 minutes combat and 20% weather allowances the Spitfire VIII safe radius of action was 200 miles clean, 320 miles with 30 gallons external, with 90 gallons 360 miles if tank dropped at target, 456 miles if tank retained until empty.

The RAF range rules gave the Tomahawk I with 132 gallons of fuel a range of 800 miles at 185 mph at 15,000 feet, Spitfire I 575 miles at 165-170mph at 15,000 feet on 85 gallons. The extra 47 gallons gave the Tomahawk 225 extra miles. Same rules: Gauntlet 626 miles, Gladiator 523 miles, Hurricane I 600 miles, Whirlwind I 590 miles.

In the second half of 1944 Spitfire IX began being fitted with rear fuselage tanks, 33, 48 and 75 gallons, the latter required careful handing and over half burnt off before more than straight and level flight, even then the volume available for the remaining fuel to move around in caused problems. It seems the improved elevators from Westland helped the situation, apparently to the point a IX could fight with a full 33 gallon rear fuselage tank. Also later IX production had 18 gallon wing tanks.

This was the best the British could do given the need for numbers. The obvious quick fix is external fuel tanks, assuming the tank could refill the internal ones at fast cruise a Spitfire IX could use around 65 gallons external for range, earlier models more, any extra fuel would be for patrol at maximum distance. In January 1944 the British report building over 13,000x30 gallon, 60x45 gallon, 486x90 gallon and 486x90 gallon for Spitfire, the Typhoon tanks were 45 gallon, amongst other types 11,757x90 gallon for P-47

From the British history Design and Development of Weapons, M M Postan, D Hay, J D Scott. It claims there were 4 basic Spitfire airframes which it labels A, B, C and D

D was the mark 21 onwards,
C was the mark VII, VIII and most Griffon marks up to XIX
A was the original which served for the marks I, II, IV. It was stretched to do the Va, Vb, VI, PR VII and XIII and the Seafire I.
B was the airframe developed from the abortive mark III fighter, it was used for the Vc, IX and XII, and presumably XVI. The main change appears to be the "universal" wing.

Mark I in production July 1939 to March 1941 (plus 50 from Westland July to December 1941), mark V in production March 1941 to September 1942 (Supermarine), to August 1943 (Castle Bromwich), to October 1943 (Westland)

Pre war RAF fighter doctrine tried to avoid standing patrols for the effects on both pilots and airframes, going on oxygen increased pilot fatigue even more. These tactics reduced the risk of fighters being caught on the ground.

Minor note, the RAAF Defence of Darwin used 3 Spitfire squadrons, 54 RAF and 457 and 457 Article XV nominal RAAF squadrons. There were enough Spitfires for the RAAF to form 79 squadron with Spitfires in April 1943, sending it to New Guinea late May 1943, ending up in the Admiralty Islands. Transferred to Darwin area in early 1945 as part of a reorganisation that saw Darwin defended by 54, 548 and 549 RAF Spitfire squadrons while 79, 452 and 457 moved forward into what is now Indonesia.

 

[Steamed_Banana]

The two neighboring small ribs were removed, and the additional skinning was added to cater for the lost rigidity.

Yeah I thought it was something like that. Do you know if any structural changes were required to increase the size of th e fuselage tank on the VIII?

 

[tomo pauk]

Yeah I thought it was something like that. Do you know if any structural changes were required to increase the size of th e fuselage tank on the VIII?

From what I understand, there were no notable changes to the internal structure. Just the volume was better taken advantage of, so the 37 gal tank was replaced with the 48 gal tank.
The increase of main fuel tankage was also supposed to be done on the Spitfire XIs from Autumn of 1944 (schematics); I don't know how many of these were actually modified.

 

[Engineman]

The +16lb rating may not have mattered at altitude but it really helped at middling alt and down low, and one thing people need to keep in mind in general, is that WW2 fighters could generally get from high altitude down to low very quickly compared to going in the other direction. In fact diving to pick up speed can be a good way to get back up to altitude (via zoom) in another place, especially useful when you find yourself in a pickle wherever you started from.

I believe this is what in part gave the Spit V legs later on in the Med, into 1943, and was also one of the secrets for survival of the P-40s, because once they dropped down below 10,000 ft they actually gained a performance advantage over most marks of the Bf 109F and G.

What made this more viable for Spitfires in general was adding the bendix carb which enabled the quick escape maneuver to get into that fast dive in crucial fewer number of seconds than before. The improved roll rate helped too of course. It also somewhat negated the escape maneuver (i.e. via zero G nose-over) that the German pilots had been relying on since the Battle of Britain.

The Bendix-Stromberg Injection carb was initially seen on the Packard built Merlins. British built Merlin's did not see a version of the Stromberg Injection carb until the PD 18 version on the Merlin 66. British built Merlins suffered the worst effects of their SU Carbs until the introduction of the RAE Restrictor was started in early 1941. The RAE anti-g modification of the SU float carbs began some time later, so many British Merlin powered aircraft were still flying with cut-out prone engines in 1942.
High Boost capable engines were pretty much reliant on the RR designed 2-piece cylinderblock and head. There were many modifications to achieve the high boost standards. A large factor was the need to achieve long service-lives for the engines. About the only service life sacrifice was with the CAM SHIP Hurricanes which would probably only fly a single combat
launch off a ship, and they were allowed to boost their Merlin II engines to 16lb.

Eng

 

[Engineman]

Hi,

As an aside to my post #598, I am interested if anyone has info about the actual effects that Rolls-Royce quantified with the use of Boost Overide in BoB Spitfires and Hurricanes?
The function of the Boost Overide removed the protection from Detonation that was usually provided by the Boost controller that limited maximum Boost.
I am interested because, the advantages but risks of the use of Boost Overide are regularly quoted by RR and Service documents, Pilot reports often quote the use of the Overide and the operation of Overide was protected by tell-tale copper wire seals that mandated engine checks if found broken. However, I have not seen any reference to engine damage that was attributed to the use of Boost overide. I am certain that this engine aspect was carefully monitored, but I have seen no further information?

Thanks for any info,

Eng

 

[MiTasol]

The tactics used by the RAF were dictated by the short range of the fighters, the short range was a result of lack of engine power, as engine power increased along came the ability to carry more weight in guns, ammunition or fuel so the use of fighter tactics should have moved with it.

And at the stage the Spitfire was designed Merlin was one of, if not the, most powerful V12 engines in production. And fighter tactics did move with the experience gained. In the opinion of those at the coal face experts there at the time fuel tank protection, heavier armour and heavier weapons were needed more than range to support the evolving tactics because the Germans had fitted heavier armour that protected the crew and had heavier weapons that could puncture the existing armour.

Using your perfect hindsight expertise how do you think they could have done better.