RAF daylight strategic bombing campaign results (2 Viewers)

[Shortround6]

I admit that I only have the figures on the N Williams site but they seem to give the Tomahawk I 1020hp at 11,600ft and performance is poor.

That power seems low and the altitude seems low.

There were a variety of Tomahawks and not all corresponded exactly to a particular P-40 model (and you had P-40s, P-40Bs, and P-40Cs), The very early ones, American, ex-French and early British (?) had NO protection let alone equal protection to late 1940 British or German fighters. I am not sure how many single gun in each wing Tomahawks the British got because I believe the ex-french aircraft had two guns in each wing.

 

[Koopernic]

snip

The P-40C/Tomahawk IIB's performance degraded due to the protection on the P-40B being felt to be inadequate (at least by american planners). More advanced (and limited capacity) self-sealing tanks were introduced along with increased armor (including armor glass for the windshield) along with the belly shackle.

So climb/turn performance dropped significantly, speed dropped more modestly.


The V-1710's good specific fuel consumption at cruise was part of the key to the longer range on US aircraft (on top of aerodynamics and -mostly- fuel capacity) So some of the range advantage would be lost by using a merlin ...

The higher fuel capacity is still going to be a major advantage, though.

For 1941 I'd still have to agree that ... inadequate or not, of existing aircraft available to the British, the Tomahawk IIA and IIB were the closest things to esxort fighters they had on hand.

snip

Hmm ... that's a more interestion suggestion, but do remember the Hispano was a larger/heavier weapon than the MG-151. (the underwing pods on the P-39Q would probably be more comparable than hispano gun pods)

Did the recon spits even use self sealing tanks for the extended range? (that'd be a major issue to consider)

With similar technology, you're going to pretty consistently have superior 1 to 1 performance for short range interceptors over long range escort fighters.

So you NEED a technological edge to manage competent escort fighters (or long range roaming intruders/penetration fighters) that are relatively close to even terms with enemy interceptors.

snip.

The Spitfire had a "D" section wing structure whereby thick skins of the leading edge and main spar formed the primary load carrying structure. Reginald Mitchell and Supermarines had long recognised that this provided an exceptionally large storage space for fuel and had intended to use this on several other designs.

"despite having a proposed wingspan of 97 feet, it nevertheless was to make use of a single spar wing supported by torsion-resistant leading edge boxes on a similar principle to that developed for the Spitfire; and, unusually for its time, fuel was to be carried in these leading edges, thereby saving weight, and with the tanks adding to the rigidity of the wing. Behind this spar component, the structure allowed sufficient room for the main stowage of bombs, thus avoiding the need for conventional tiered bomb stowage which would have substantially increased the fuselage cross-section and its drag component – another example of Mitchell ingenuity."

From Drawing 31600 Sheets 5/6 supermarine 318 to air ministry B.12/36 showing leading edge tanks and stowage of 27x500 lb/29x250 lb bombs.
R J Mitchell and Supermarine: R. J. Mitchell's Bomber and his death.

Nevertheless its interesting to note that many of the engineering decisions made by RJ Mitchel and J Smith over ruled the possibility of using the full wing for fuel storage. For instance Mitchell did not like the idea of synchronised cowling machine guns or a motor gun because it inevitably 'thickened' the fuselage. Had weaponry been mounted on the cowling, between the V block or in the wing roots (as in the Fw 190, He 112 and several Soviet aircraft) the wings might have been left clear. There were no doubt other issues such as lack of a suitable guns, the inability of Merlin engine propeller combination to take this without re-engineering. The US 0.5" Browning with hydraulic hydrostatic interrupter gear in the wing roots seems the easiest to me. Likewise the rejection of 'gondola' hispano weapons on the Spitfire by J Smith.

It seems neither man was motivated by the Air Ministry to increase the range of their aircraft.

Somewhat more puzzling is the lack of a long range escort specification by the RAF unless once considers the Typhoon and its teething problems.

H Dowding Watson Watt came up with Radar and a grand plan for defence of their island as early as 1934 having developed and deployed a completely integrated defence system by 1939. Couldn't someone see that the enemy could do the same and that their B.12/36 specification (Stirling, Halifax BI, Supermarine 317 or 318 etc) would be similarly vulnerable? I suspect had they looked at this possibility the supermarine 318 would have been the clear winner over Stirling and Halifax due to its much higher speed (330mph), a speed while not as fast as a German fighter, would have made interception in force less likely or of less duration and simplified the task of any escort fighter.

The Germans have an excuse since radar in Germany was an invention of the signals branch of the Germany navy who applied ideas on sonar to radio, they didn't go out of their way to inform the Luftwaffe and tried to lock their suppliers into exclusivity.

The range of the P-51 it seems to me came down to 'serendipity' of the NA sales and engineering team. Using the laminar profiles and their large capacity, keeping the radiators and their plumbing away from using space in the wings.


My understanding is that the Tomahawk IIA (P-40B) carried 131 Imp Gallons (160 US Gallons) but that later versions dropped down to 120 Imp gallons) This is still well above the Spitfire III/V's 85 gallons and similar for P-39.

While I of course accept the altitude limitations of the Allison P-40B I suspect the two speed Merlin XX would have given the power, altitude power and competitive cruise capability to the Allison to be acceptable in say a P-40B or P-40C airframe. I would imagine that the LF gear on the Merlin XX would also aid cruising ability at altitude.

While the Merlin P-40B or C would never have the power to weight ratio of the Spitfire V I note that the Allies did have a technological advantage and that is superior fuel and that the Performance of the DB601/605 series always lagged the Merlin by 15%-20% AFAIK. The later Me 109F4 and 109G1 are impossible to match with a single stage Merlin/p40 but there is a window between mid 1941 to early 1942 where a Merlin XX P-40B+ could be in the game against the Me 109 and Me 110 types enough to reduce bomber losses. The appearance of the Me 109G and the Fw 190A3/A4 would end that, I would think decisively, in the Luftwaffe's favour. However mid 1942 also might have allowed a hypothetical Merlin XX/ Packard V-1650-1 powered Mustang or long range Spitfire VII or VIII to partially take over (they had the "C" wing and thus wing tanks, the IX had the "C: wing but lacked the wing tanks)

I see these missions as not being too deep into Germany and escorted by the shorter ranged Spitfires 2/3rds of their Journey.

 

[Greyman]

I'm referring to the US daylight campaign and interceptions by the Luftwaffe.

Outside of what you were referring to - but I thought these images were pretty striking:

Bf 109 on a Spitfire on a Ju 88
Mustang on a Fw 190 on a Lancaster

EDIT: ten months later - new image (P-51 on a Bf 109 on a B-17)

 

[kool kitty89]

I have never heard of the RAF pushing the Merlin beyond its normal operating limits with the exception of 12lb boost being used for longer than five minutes. That did happen a number of times.

As for the P40 in the BOB it was never going to happen being nine months too late for the battle. Even then it lacked climb, performance, protection, agility and altitude performance. The engine only produced 1040hp the 12lb boost Merlin was looking at 1,300hp a significant difference. A P40B could hold its own up to approx. 15,000ft but above that forget it and I think that only made service in mid 41..

I meant that the Battle of Britan (and prior action in France) forced the RAF and Rolls Royce to put more aggressive engine testing/experimentation in place, developing emergency ratings on engines years before the US did. Same engines ... all a matter of testing in the factory and in the field.

At normal 3000 RPM, the V-1710-33 was officially limited to only 37.2 mm Hg manifold pressure at 14,500 ft (that's +3.5 psi boost).
If overboosted to 46" Hg (just shy of +8 psi boost), it could pull 1,280 hp at 9,000 ft (same as the Merlin I's FTH for 1,300 hp )
That's without resorting to overspeeding to boost supercharger output. (3200 RPM makes the 8.8:1 gearing act like an effective 9.4:1 supercharger ratio would at 3000 RPM)

The 1st production P-40 was delivered at June 1940, the 1st Tomahawk I was delivered (still it is in the USA) at Sept 1940. Production-wise, they might qualify for the BoB, but obviously not when we count in the training and logistic needs.
The early P-40 will climb better than any subsequent P-40, being far lighter. With 120 US gals, the P-40 was at 6800 lbs and doing 357-360 mph tests.

Unless you count intial climb on some loadouts for later P-40s in WER power ... definitely the fastest climber on mil power.

Protection of 1940 BoB fighters was not equal with what fighters carried in 1941, let alone, say, in 1943.

I think the P-40B was fairly close to late model Spitfire Mk.Is maybe closer to Mk.IIs. P-40Cs got the totally redesigned fuel system using self-sealing cells rather than conventional tanks with sealing material applied to the exterior. (Cs also added armor glass to the windshields as standard)

The Spitfire is not the only aircraft that fought during the BoB. Early P-40 does have it's shortcomings, but it's performance was closer to the Spit and 109E, than to the Hurricanes and Bf 110.

Roll rate, overall control weights at high speeds, stall characteristics, and dive acceleration would be useful characteristics too. (plus lack of negative G problems) Then there's the higher fuel capacity and good fuel economy allowing a more flexible mission profile than the spit/hurri/109. (longer endurance, longer loiter time ... roaming patrols might be logistically difficult though -that range/endurance would have made it more interesting for the Germans as an escort or fighter-bomber compared to the 109)

The level speed the P-40 managed in spite of being heavier with lesser engine performance seems to point to it being a cleaner airframe than the Spitfire or 109 as well, and while that might not mean too much on the whole it does imply better dive acceleration than any of the BoB fighters. (the one place that higher weight becomes an asset)

Rear visibility is a bit better on the P-40 too, with the hollowed out and glazed fuselage section immeditately rear of the cockpit.

Power to weight ratio might have been worse than the Hurricane, but the P-40B's climb rate figures seeem to compare favorably to the Hurricane Mk.I, though sustained turn-rate was worse. Quite possibly a better interceptor than the Hurricane, though not the Spitfire. (ironically, the 109E's performance and armament best fit the bomber interception role of the lot)

Nevertheless its interesting to note that many of the engineering decisions made by RJ Mitchel and J Smith over ruled the possibility of using the full wing for fuel storage. For instance Mitchell did not like the idea of synchronised cowling machine guns or a motor gun because it inevitably 'thickened' the fuselage. Had weaponry been mounted on the cowling, between the V block or in the wing roots (as in the Fw 190, He 112 and several Soviet aircraft) the wings might have been left clear. There were no doubt other issues such as lack of a suitable guns, the inability of Merlin engine propeller combination to take this without re-engineering. The US 0.5" Browning with hydraulic hydrostatic interrupter gear in the wing roots seems the easiest to me. Likewise the rejection of 'gondola' hispano weapons on the Spitfire by J Smith.

It seems neither man was motivated by the Air Ministry to increase the range of their aircraft.

The .50 browning or (if they'd taken an interest) .50 vickers (might have had better synronized RoF too and lighter and more compact -2 wing root guns plus 2 cowl guns would have been decent even with the lower powered vickers rounds).
Mounting hispanos in underwing pods was suggested too. Use fuel tanks in the wings and a pair of 20 mm underwing and it might have been useful. (depends just how much drag the installation added)

Tony Willaims has a couple articles pointing out the realistic potential for the hispano to be made synronization capable too. I'm not sure about engine-mounting it though, that'd depend on the Merlin's design. (the V-1710's supercharger arrangement didn't allow this ... neither did the propeller hub positioning used on the C series V-1710s) It might have been a possibility though. A mix of HMGs and nose cannon would have been pretty useful too ... and allowed WORKING cannon-armmed single engine fighters during the BoB. (1 20 mm plus 2 or 4 HMGs is a pretty useful fighter armament)

Somewhat more puzzling is the lack of a long range escort specification by the RAF unless once considers the Typhoon and its teething problems.

The Typhoon's range hardly fit the requirements for that role either, even without teething troubles.

My understanding is that the Tomahawk IIA (P-40B) carried 131 Imp Gallons (160 US Gallons) but that later versions dropped down to 120 Imp gallons) This is still well above the Spitfire III/V's 85 gallons and similar for P-39.

The P-40C carried tanks of 134 US gal (111.7 Imp), but the P-40E expanded that to 157 gallons (130.7 Imp). The P-40N reduced that to 122 US gallons. (on a side note, if the same proportions are applied for the 160 gal vs 134, the P-40E's configuration might have allowed some 187 US -156 imp- gallons with P-40B style tanks)

 

[Shortround6]

The main trouble with all (or most) of the P-40s "advantages" is that they only apply to altitudes that are too low to be useful in the BoB or for an escort fighter over Europe in 1941-42.

And it seems a lot of the "book" figures for the P-40B were done at a rather unrealistic weight for the proposed duties.

http://www.wwiiaircraftperformance.org/P-40/P-40B_Official_Summary_of_Characteristics.jpg

Performance figures are for 6835lbs. The "normal" gross weight of 7326lbs has the plane holding 120 US gallons of gas, not the 160gal over load condition.

Getting rid of 490lbs of useful load means ripping out guns and armor and/or fuel/oil ( the pilot has to stay). You only had 720lbs of fuel to make 120 gallons. Performance with 38.33 gals of fuel on board is rather useless.

We can do the easy thing first and ditch ammo.
Cut wing guns from 500rpg to 350rpg will save 36lbs =6 gallons
Cut fuselage guns from 380rpg to 200rpg will save 108lbs (.50 cal ammo is heavy)= 18 gallons.
If we aren't going to use full fuel tanks we don't need a full oil tank. If we pull 42lbs of oil (roughly 1/3rd) we can get another 7 gallons of gas.

We are now up to 69.33 US gallons (maybe 57.7Imp) gallons?

Put the pilot on a diet??

P-40 is NOT going to perform to book figures with a "normal" load let alone the 160 gallon overload.
Unless you over-rev the engine any improvement in performance from increased boost will be at under 13,000-14,500ft. And with 109s coming over the top of Hurricanes during the BoB that doesn't look so good.

The .50 browning or (if they'd taken an interest) .50 vickers (might have had better synronized RoF too and lighter and more compact -2 wing root guns plus 2 cowl guns would have been decent even with the lower powered vickers rounds).
Mounting hispanos in underwing pods was suggested too. Use fuel tanks in the wings and a pair of 20 mm underwing and it might have been useful. (depends just how much drag the installation added)

.50 cal Browning is a lot of weight for not a lot of result in synchronized mountings. The Vickers .303 gun was subject to an amazing variety of jams and was NEVER placed were the pilot or crewman could not get to it to working the charging handle/lever and/or beat on it with a gloved hand. A lot of schemes were proposed for the Hispano, it turned out the Hispano liked fairly rigid mountings and had a higher tendency to jam in less rigid mountings. Under wing guns place the guns with a longer lever moment in relation to the aircraft's CG and can cause even more "dip" on firing. One explanation for the six .303s in the Beaufighter was that the four 20mm guns in the bottom of the nose caused the plane to dip and go off target. True or not????

And once again, weight is more important at times than drag. the 109 gunboats were still fast but climb, turn and roll all suffered to the point where they needed non-boats to handle the opposing fighters.

 

[pbehn]

Outside of what you were referring to - but I thought these images were pretty striking:

Bf 109 on a Spitfire on a Ju 88
Mustang on a Fw 190 on a Lancaster

View attachment 286512

The thread is about RAF daylight raids, a photo of an Fw 190 being shot at while attacking an RAF Lancaster is completely on topic, I dont know how the discussion was turned around to exclude lightly armed German and British bombers and made to exclusively consider USAF deep penetration raids. The Lanc was the RAFs frontline strategic bomber, it applies to this thread.

 

[kool kitty89]

The main trouble with all (or most) of the P-40s "advantages" is that they only apply to altitudes that are too low to be useful in the BoB or for an escort fighter over Europe in 1941-42.

And it seems a lot of the "book" figures for the P-40B were done at a rather unrealistic weight for the proposed duties.

http://www.wwiiaircraftperformance.org/P-40/P-40B_Official_Summary_of_Characteristics.jpg

Performance figures are for 6835lbs. The "normal" gross weight of 7326lbs has the plane holding 120 US gallons of gas, not the 160gal over load condition.

Performance for pretty much any actual service-test aircraft tended to be significantly below the factor/aproval tests. The P-40D/E/F/L/M/N usually failed to meet their specified level speed if not climb performnace as well. Same is true for the Hurricane and Spitfire (some models more than others). Propellers used could make a big difference too, even aside from early examples of fixed-pitch ones.

Getting rid of 490lbs of useful load means ripping out guns and armor and/or fuel/oil ( the pilot has to stay). You only had 720lbs of fuel to make 120 gallons. Performance with 38.33 gals of fuel on board is rather useless.

We can do the easy thing first and ditch ammo.
Cut wing guns from 500rpg to 350rpg will save 36lbs =6 gallons
Cut fuselage guns from 380rpg to 200rpg will save 108lbs (.50 cal ammo is heavy)= 18 gallons.
If we aren't going to use full fuel tanks we don't need a full oil tank. If we pull 42lbs of oil (roughly 1/3rd) we can get another 7 gallons of gas.

Ditching the wing guns entirely might be better in that case ... depending on how much weight you put in nose mountings and concentrated fire being superior. (even with the low RoF of the .50s when synched)
Plus it's 50 vs 30 cal performance here. If you're dealing mostly with light/fragile structured opponents, the 4x .30s might be preferable to using the .50s at all. (with decent armor and strong structures, the .30s would be much less useful anyway)

Also depends if you're talking intercept or escort duty. (against small fighters, the lighter armament would be more acceptable)

.50 cal Browning is a lot of weight for not a lot of result in synchronized mountings. The Vickers .303 gun was subject to an amazing variety of jams and was NEVER placed were the pilot or crewman could not get to it to working the charging handle/lever and/or beat on it with a gloved hand.

I'm not sure the .50 vickers gun had those same problems, the tests I've seen show it to be fairly reliable ... but it never entered RAF service, so there's no field experience to go by for aircraft use.
The guns and ammo were both significantly ligher than the Browning though.

And aside from all that, there's still the issue of concentration of fire vs rate of fire. (the former is less useful if you're a poor shot though, 'shotgun' effect of more guns with staggered convergence would be preferable there)

And once again, weight is more important at times than drag. the 109 gunboats were still fast but climb, turn and roll all suffered to the point where they needed non-boats to handle the opposing fighters.

If we were talking Spitfires with nose armanets on the level of the 109, then yes, that'd be worth exploring, but I was suggesting a REDUCED armament compared to the Spit V/IX though more potent than the 8-gun early marks. (a single pair of underwing cannons or even faired close and half-burried in the wings -with the feed mechanism totally internal still, occuping the rear of the wing but freeing up the leading edge boxes for fuel.)

Now the added FUEL would still be an issue of adding weight, but that's always going to be a factor for escort fighters. The P-51 could hardly escape those problems itself. (a long range spit might have been significantly ligher than the P-51 too, though certainly slower in level speed using similar engines)

 

[Glider]

The thread is about RAF daylight raids, a photo of an Fw 190 being shot at while attacking an RAF Lancaster is completely on topic, I dont know how the discussion was turned around to exclude lightly armed German and British bombers and made to exclusively consider USAF deep penetration raids. The Lanc was the RAFs frontline strategic bomber, it applies to this thread.

I totally agree with this statement and as an aside note that the Lancaster is clearly evading. Its a great photo

 

[Shortround6]

Performance for pretty much any actual service-test aircraft tended to be significantly below the factor/aproval tests. The P-40D/E/F/L/M/N usually failed to meet their specified level speed if not climb performnace as well. Same is true for the Hurricane and Spitfire (some models more than others). Propellers used could make a big difference too, even aside from early examples of fixed-pitch ones.

It is one thing to miss the test numbers with service aircraft, it is another to use a test weight that is hundreds of pounds lower than the actual service weight.

Ditching the wing guns entirely might be better in that case ... depending on how much weight you put in nose mountings and concentrated fire being superior. (even with the low RoF of the .50s when synched)
Plus it's 50 vs 30 cal performance here. If you're dealing mostly with light/fragile structured opponents, the 4x .30s might be preferable to using the .50s at all. (with decent armor and strong structures, the .30s would be much less useful anyway)

Your synched pair of .50 cal guns are lucky if they are firing 16 rounds a second. The MG 151 cannon was firing 10-12 rounds per second.
four .303 Brownings (or .30 cal) were firing 72-80 rounds per second.

The pair of .50 cal guns weighed 150.5 lbs and even 200rpg added about 120lbs or 270lbs total.
the four .30 cal guns weighed 95lbs and using the full 500rpg added 127.4 lbs or 222.4lbs total.

I'm not sure the .50 vickers gun had those same problems, the tests I've seen show it to be fairly reliable ... but it never entered RAF service, so there's no field experience to go by for aircraft use.
The guns and ammo were both significantly ligher than the Browning though.

The .303 Vicker's gun was pretty near unbreakable, which is a different form of reliability ( British Paratroopers were using a few in Aden in 1960, years after it was "officially" retired.) That didn't mean the gunners manual didn't list 27 different possible jams. Usually diagnosed by the position the crank handle stopped at. Most jams (at least in ground guns) could be cleared fairly easily. Since the .5in gun was pretty much just a scaled up .303 gun it is hard to believe it wouldn't have pretty much the same characteristics.
A Browning sized to take the British .5in cartridge would certainly be interesting however. A British version of the Japanese Ho-103.

 

[kool kitty89]

The .303 Vicker's gun was pretty near unbreakable, which is a different form of reliability ( British Paratroopers were using a few in Aden in 1960, years after it was "officially" retired.) That didn't mean the gunners manual didn't list 27 different possible jams. Usually diagnosed by the position the crank handle stopped at. Most jams (at least in ground guns) could be cleared fairly easily. Since the .5in gun was pretty much just a scaled up .303 gun it is hard to believe it wouldn't have pretty much the same characteristics.
A Browning sized to take the British .5in cartridge would certainly be interesting however. A British version of the Japanese Ho-103.

The pre-war .50 browning was showing higher rates of stopages than the vicker's too, from what I recall ... but the vicker's gun wasn't developed further, and the browning was. With that it's broad speculation to suppose the vicker's gun would have improved substantially. We know the browning did and we know it converted well to the .50 vickers round (lighter and faster firing than the existing vickers guns or italian guns using that ammunition).

The Japanese also developed the .303 vicker's further, pushing it to 900 RPM, but I have no idea if they improved the jamming problems.

Japanese developments certainly showed the further potential the basic browning design had though from 12.7 mm to 20 mm to 30 mm to 37 mm ... a shame (and quite odd) that the US didn't pursue further development. (I've seen some claims about .60 cal browning guns -unrelated to the MG-151 derived guns aside from possibly using the same ammunition- but very little information on them)

 

[stona]

the 109 gunboats were still fast but climb, turn and roll all suffered to the point where they needed non-boats to handle the opposing fighters.

Indeed they were.

There is a generally cavalier attitude expressed on forums like this today towards alterations to aircraft (I am most definitely not aiming this at SR, though I've quoted him above). People seek to add fuel and/or tanks, auxiliary tanks and make alterations to armament etc as if these were simple things to do. If the were places like the A&AEE would not have been needed.

As an example I just read elsewhere that one of Australia's greatest fighter pilots, Clive Caldwell, experimented with a Spitfire VIII armed with four cannon (Morotai, 1945). It was an effort to up the hitting power of the Spitfire in a close support role. He concluded that the handling of the aircraft was so degraded by the addition of the two cannon that it would be dangerous for the average pilot to fly such an aircraft at low level. The idea was subsequently abandoned.

 

[kool kitty89]

As an example I just read elsewhere that one of Australia's greatest fighter pilots, Clive Caldwell, experimented with a Spitfire VIII armed with four cannon (Morotai, 1945). It was an effort to up the hitting power of the Spitfire in a close support role. He concluded that the handling of the aircraft was so degraded by the addition of the two cannon that it would be dangerous for the average pilot to fly such an aircraft at low level. The idea was subsequently abandoned.

Hmm, more degraded than the Hurricane IIC? Though with the hurricane already being a heavier and higher drag airframe, the percentage of performance loss might have been less dramatic. (similar might have been true comparing a 6 gun P-40E/F/L/M with a re-armmed 4 hispanos)

 

[kool kitty89]

The thread is about RAF daylight raids, a photo of an Fw 190 being shot at while attacking an RAF Lancaster is completely on topic, I dont know how the discussion was turned around to exclude lightly armed German and British bombers and made to exclusively consider USAF deep penetration raids. The Lanc was the RAFs frontline strategic bomber, it applies to this thread.

In this line of thinking, what would be the combat range or radius requirements for a useful escort fighter? Drop tank equipped spitfires could range decently far into France. Let alone with modifications for more modest internal tankage expansion. (and more emphasis on 100+ gallon drop tanks earlier)

In that context, the P-39/P-400 Aracobra would have been more appealing than the P40 too. Decent enough range, significantly better speed, dive, and climb rate. (deleting the wing guns probably would have been a reasonable move as well)
Same altitude problems as the P-40, but bigger edge in level speed, dive, and not as weak in climb or turn rate.

The P-39N brought the higher alt 9.6:1 blower engine too ... though that would have been around the same time the Mustang was available anyway. (and even without drop tank provisions, the Mustang Mk.I and II would have managed longer combat radii than the Spitfire or Aracobra with drop tanks -the MkII/P-51A had better altitude performance than the similarly engined Aracobra too, at least in level speed -climb defeats RAM performance)

A Merlin 60 series spitfire with expanded fuel capacity may have made a better escort than an allison powered P-51 though. Hypothetical V-1650-1 powered P-51s might have had an advantage (certainly over Spit Vs). Once Mustang IIIs become available they're the obvious choice for escort.


The altititudes for the bombers in question also matter here. That includes medium altitude heavy bomber runs and potentially reducing bombload and pushing higher cruise altitudes.

 

[stona]

Hmm, more degraded than the Hurricane IIC? Though with the hurricane already being a heavier and higher drag airframe, the percentage of performance loss might have been less dramatic. (similar might have been true comparing a 6 gun P-40E/F/L/M with a re-armmed 4 hispanos)

The problem wasn't so much performance loss as it was the detrimental effect on handling. Many of the 'solutions' and fixes so lightly proposed (fuselage tanks being a good example) had serious effects on the Spitfire's stability. It's all very well saying that once the tank was emptied the handling and stability would return to more normal parameters, but by then a less able pilot might have killed himself and destroyed the aircraft.
During a war some measures unthinkable in peace time might be and were allowed, but service aircraft, with very few exceptions, had to be flyable by the least able pilots, not just the best. Caldwell was well aware of this.

The Lancaster was considered an easy aircraft to fly, with benign handling. Due to Bomber Command/Harris' reluctance to allow its use at the Heavy Conversion Units many accidents occurred and many lives were lost due to lack of familiarity with the type. Coming from a Halifax or Stirling did not make flying a Lancaster a simple thing.
Training, training and more training was required and many WW2 pilots didn't get it. The idea that most of them could handle any aircraft in which modifications had caused some instability or malicious handling characteristics is silly.

Cheers

Steve

 

[Shortround6]

Hmm, more degraded than the Hurricane IIC? Though with the hurricane already being a heavier and higher drag airframe, the percentage of performance loss might have been less dramatic. (similar might have been true comparing a 6 gun P-40E/F/L/M with a re-armmed 4 hispanos)

It is not the "performance loss" that mattered, at least in this case. Handling refers to things like roll response and pitch response. Even IF you can keep the CG the same (balance) the inertia may change with the added weights causing the response to change. And this is different than peak rolling rate or peak pitch response.
take a yard stick and place a 2 0z weight at both 17 and 19 in. hold at the 18in mark and wobble it left and right (ends go up and down). Now move the weights to 12in and 24in and try again and then to 0in and 36in and try. Same weight, same balance but very different responses.
An anecdote told to me by my brother-in-law. He owned for a few years a Mudry Cap 10

Not this one.
One day he met with some old collage buddies who suggested that he take them up in a rented Cessna 172. He suggested he needed to take a check ride in a 172 since he had not flown one in several years. He went up for 1/2 hour with an instructor and upon landing told his friends it wouldn't be safe for him to fly the 172. He was consistently under controlling the 172 since it needed much higher effort control inputs to get anything to happen than he was used to with the Cap 10.
The reverse killed a lot of pilots in WW I and a fair number in WW II. Going from sedate and forgiving trainers to fast responding (and some unforgiving) fighters caused many low time would-be fighter pilots to over-control their aircraft and crash.
One reason duel control (or at least dual cockpit) conversion trainers were finally put into use.

Please remember that EVERY Spitfire from the MK Vc onward had the capability of being fitted the four Hispano guns. The gun bays were there, the holes in the leading edge spar were there, the space for the ammunition tray/box was there.
Shortage of guns, problems heating four cannon, loss of climb rate and turning have all been put forward as reasons why the four gun setup was not used very much but there seem to be darn few (if any) conversions done in the field.

 

[Edgar Brooks]

Hmm, more degraded than the Hurricane IIC?

The Hurricane IIC had just the four 20mm cannon; the Spitfire VIII was designed to carry four cannon AND four .303" Brownings. The R.A.A.F. were expected to intercept nimble Zeros at above 20,000', and Caldwell knew perfectly well the VIII, with 8 guns, would never do it.

 

[Glider]

The Hurricane IIC had just the four 20mm cannon; the Spitfire VIII was designed to carry four cannon AND four .303" Brownings. The R.A.A.F. were expected to intercept nimble Zeros at above 20,000', and Caldwell knew perfectly well the VIII, with 8 guns, would never do it.

This is new to me \I admit, can you supply something to support this idea

 

[kool kitty89]

The problem wasn't so much performance loss as it was the detrimental effect on handling. Many of the 'solutions' and fixes so lightly proposed (fuselage tanks being a good example) had serious effects on the Spitfire's stability. It's all very well saying that once the tank was emptied the handling and stability would return to more normal parameters, but by then a less able pilot might have killed himself and destroyed the aircraft.
During a war some measures unthinkable in peace time might be and were allowed, but service aircraft, with very few exceptions, had to be flyable by the least able pilots, not just the best. Caldwell was well aware of this.

Yes, this is also why I was focusing more on the potential leading edge wing tanks on the spitfire than the rear tank. That placement seems like a less problematic location for degrading CoG positioning. (plus issues with being nose-heavy usually caused fewer problems with stability -and especially stall/spin characteristics than being tail heavy)

Managing good, stable handling would have been a more important consideration for the suggestion of underwing cannon pods too. If those couldn't be installed without degraded handling characteristics (compared to in-wing mountings), it would be an unacceptable compromise. That suggestion was also posed in the context of having 2 wing cannons be the ONLY armament and intended mainly for escort duties and fighter v fighter combat. Or at least that was one of the contexts it came up in. (along with the suggestion for nose armaments and motor cannon mountings)

Training, training and more training was required and many WW2 pilots didn't get it. The idea that most of them could handle any aircraft in which modifications had caused some instability or malicious handling characteristics is silly.

Training and actual knowledge of the aircraft's characteristics. Some handling problems were less officially known than others. The CoG specific stability issues on the P-39 were noted in the field before officially documented at Bell. (and specific to being nose-light/tailheavy)

Tail heavy conditions seem to be one of the biggest problems for stability, at least in single-engine aircraft ... especially fighters. (which are inherently less stable for maneuverability needs)

I haven't seen that many specific claims on this issue, but handling characteristics seem to be one of the more definitive advantages of the P-40 over the P-39. (in terms of ease of stability and ease of flying, less so compared to actual turn/roll performance ... similar to comparing the hurricane to the spitfire in some respects, except not the same gap in performance)


And taking a step back:

Indeed they were.

There is a generally cavalier attitude expressed on forums like this today towards alterations to aircraft (I am most definitely not aiming this at SR, though I've quoted him above). People seek to add fuel and/or tanks, auxiliary tanks and make alterations to armament etc as if these were simple things to do. If the were places like the A&AEE would not have been needed.

I mostly try to think in terms of reasonable hypothetical thinking/foresight (not hindsight) of engineers and planners from the period. (ie choices that made sense to them ... even if they didn't make them historically)

In terms of altering the Spitfire's loadout it's mainly a question of trying to figure out SOME acceptable escort fighter for Brittain to use. If the Spitfire could be configured to allow similar or longer range to the P-40 (or even P-39) without irreparably degrading performance and/or handling characteristics (and performing better than the P-40 itself), then that would have been worth persuing.

Discussion of USAAF style long range penetration bombing runs skewed the discussion a bit further, but for shorter range missions, more modest modifications may have been reasonable. (that and potentially using Mustangs without drop tanks ... or hypothetical British P-38s)

Hmm ... shifting the topic a bit, but still somewhat relvant: in terms of similar manufacturing cost/resources, would ordering more early model P-38s (or modified turbo-less ones) have been more useful than similar resources going into P-39 and/or P-40 production? (this includes potential use as a medium altitude escort fighter)

 

[stona]

The Hurricane IIC had just the four 20mm cannon; the Spitfire VIII was designed to carry four cannon AND four .303" Brownings. The R.A.A.F. were expected to intercept nimble Zeros at above 20,000', and Caldwell knew perfectly well the VIII, with 8 guns, would never do it.

Not in 1945. The Aussies understood that they would be carrying out a close support role in support of the Americans which is why they were looking at flying four 20mm cannon and why Caldwell carried out the unofficial trials.

Spitfires fitted with four cannon are as hard to find as rocking horse poop. I believe it was you that said the four cannon set up was used to ferry weapons to Malta, but this wasn't an intended operational configuration even there, though who knows what happened short term in the chaos of that island? I know of a few pictures of four cannon Spitfires, supposedly on Malta.

Interesting wheel chocks

Cheers

Steve

 

[Greyman]

Definitely used over Malta. Luftwaffe reported them in action as well.