RAF daylight strategic bombing campaign results

[kool kitty89]

I'm sure it's been suggested before too, but in the previous discussion on Merlin 20 series (V-1650-1) powered Mustangs, particularly on the issue of actually proposing/testing such a prototype, the suggestion of acquiring a British manufactured Merlin for said testing didn't arise. Given the fact that it was being designed and manufactured to a British order (and the fact that both the XP-40L and the later experimental Merlin 60 powered Mustang used British manufactured engines for testing) it would have made plenty of sense for this to have been done. More so if the British themselves had requested such a configuration and supplied a test engine.

Such a request might have been the most likely way for an V-1650-1 powered Mustang to actually make it into production. (granted, with the timing of V-1650 production, the initial run of mustangs would still have to start with Allison powered models ... or have British Engines allocated to them -rather unlikely)

Hell, if they'd proposed that back during the NA-73 prototype design and construction phase, a Merlin engine might have been allocated to the project before the American V-1710 was even available. (due to US production allocation priority delays for the V-1710) Granted, that would be earlier than than the P-40 flew with a Merlin ... but rather less crazy than the likes of what the British later did reguarding jet developments. (admittedly different context, but as far as radical decisions, sacrificing the two flight worthy Goblin engines -and a third ground-test only one- was a much greater risk than providing a Merlin XX for testing in 1940, a couple months after the initial Hurricane Mk.II prototypes had received theirs)

Testing that early would still mean having to wait until late 1941 before V-1650s were available, or allocating british-built merlins to Mustangs ... which would also complicate logistics. (either shipping British engines to be installed in the US or shipping engineless airframes to the UK -removing the possibility of ferry flights)

 

[Shortround6]

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)

Perhaps but then you would have needed a crystal ball. Because of the crash of of the XP-38 and delayed testing it wasn't ordered as soon as the P-40 and P-39 which means in 1940 they built 1 P-38, 13 P-39s and 778 P-40s. In 1941 they built 207 P-38s, 926 P-39s and 2248 P-40s. P-38 production catches up (sort of) in 1942 with 1479 P-38s compared to "only" 1932 P-39s. P-40s were 3854.
Loosing a number of months production of either the P-39 or P-40 at that stage of the war would have had a serious impact on the American forces.

 

[Koopernic]

i do not think we have entered the realm of cavalier conjecture in this case though we've had some crazy propositions, I appreciate however much needs consideration, increase the weight and its not just C of G but tail plane incidence that might need adjustment. Historically PRU reconnaissance Spitfires did carry full span 66 gallon wing tanks on each wing. Spitfires Mk 21,22,24 all entered service with 4 x 20mm Hispano's, these were fully length Hispanos except on the Mk 24. This was of course with the "new" or "revised" wing. In General increases in weights may need redistribution of equipment to achieve a satisfactory centre of gravity, the Spitfire needed bob weights to add control force in pull-outs and so forth.

Below is the Spitfire "C" wing first introduced on the Mark V.

Each wing had two positions just outside the propeller arc which could take either a US 0.5 inch Browning or 20mm Hispano. Although two Hispanos could be fitted in each wing it was usual to carry only one and either a 0.5 inch Browning in the adjacent station or that station was simply plugged. In the case that the station was plugged the 0.303 Browning's in the outboard wings were carried.

As can be seen there is an 18 Imperial gallon tank inboard of the guns (used for some reason only on some variants such as the long range Mk VIII the Australians used in the Pacific).
The two heavy gun stations occupy prime real estate in that it looks like a another 18+ gallon tank could be fitted there. IE 36 gallons in each wing instead of only 18 and more like 40 if the common sidewall is considered. Such a Spitfire would match the P-51 without tail tank but would only be able to carry 4 x 0.303 guns in its outboard stations. Is that enough to deter fighters?

To me it look like a 0.5 inch Browning with ammunition could be fitted between ribs 1 and 2 or 3 and 4 to be synchronised hydraulically. There might be plumbing there to the radiators that would have to be moved.

The revised wing spitfires could also carry small fuel tanks of about 6 gallons in the outer wing stations, their 0.303 guns being of little use.

Underwing armament I think would do the trick since there is not extra weight being added, the guns are only being moved.

 

[tomo pauk]

The LE tanks were offering 2 x 13 imp gals per aircraft, used on Mk.VII/VIII (also for MTO) and Mk.XIV. Installing any armament inboard of the main wheel wells will be next to impossible due to radiators taking a lot of volume there.
FWIW, here is my take. Two guns next to the wheel well; possibilities for the extra fuel tankage are in front of the main spar (outboard of the guns); behind the main spar; area marked with '?'.

 

[kool kitty89]

The LE tanks were offering 2 x 13 imp gals per aircraft, used on Mk.VII/VIII (also for MTO) and Mk.XIV. Installing any armament inboard of the main wheel wells will be next to impossible due to radiators taking a lot of volume there.
FWIW, here is my take. Two guns next to the wheel well; possibilities for the extra fuel tankage are in front of the main spar (outboard of the guns); behind the main spar; area marked with '?'.

Hmm, perhaps 4x .50 guns or a single pair of 20 mm cannons? (the latter would be lighter depending on the ammunition load, granted 2x .50s and 2x 20 mm would work too, or allowing all 3 configurations ... which I suppose they already did -4 .50s was possible, just not really used)

Given the compact placement of the inner 4 gun points, I'm not sure the earlier suggestion of resorting to under-wing pods would be all that useful. There's SOME leading edge space to be gained, but not a whole lot. (so more a question of the added drag being worth the added fuel -even if you keep weight down by limiting armament to a single pair of cannons, and embed the guns as flush to the wing as possible, keeping ammunition boxes within the wings themselves still, since only the leading edge wing space would be used for fuel)

 

[Edgar Brooks]

To me it look like a 0.5 inch Browning with ammunition could be fitted between ribs 1 and 2 or 3 and 4 to be synchronised hydraulically. There might be plumbing there to the radiators that would have to be moved.]

You might need to land and take off without undercarriage, too, since the oleo legs go across that area.

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

In January 1944, the Air Ministry finally settled on the armament of 1 x 20mm + 2 x .303", but only on the V IX. For those two Marks (only) there was a modification "To introduce the single blister door called for under mod 683 as a retrospective item." Mod 683 was to standardise the armament as above.
However, on 15-12-43, another mod (769) was "To introduce a cannon gun door having two small blisters in place of the existing single large blister," and that was solely for the Mk.VIII; two small blisters would only be needed for two cannon. There had been talk of fitting the short-barrelled Mk.V Hispano in the VIII, but that came to nothing (maybe the Tempest had priority.)

 

[Koopernic]

You might need to land and take off without undercarriage, too, since the oleo legs go across that area.

In January 1944, the Air Ministry finally settled on the armament of 1 x 20mm + 2 x .303", but only on the V IX. For those two Marks (only) there was a modification "To introduce the single blister door called for under mod 683 as a retrospective item." Mod 683 was to standardise the armament as above.
However, on 15-12-43, another mod (769) was "To introduce a cannon gun door having two small blisters in place of the existing single large blister," and that was solely for the Mk.VIII; two small blisters would only be needed for two cannon. There had been talk of fitting the short-barrelled Mk.V Hispano in the VIII, but that came to nothing (maybe the Tempest had priority.)

There might still be room there (ribs 3/4 or 2/3) for a smaller weapon since these ribs are inboard of the wing attachment.

Obviously the 4 gun armament was achieved on the Spitfire Mk 21/22/24 with its revised wing however the "Super Spitfire" Mk XVIII, which was a backup design to the Mk 21, and essentially an improved Mk XIV Using stainless steel stringers for strength) didn't carry this armament.

It seems to me there were control and stability issues that still needed to be solved.

 

[Glider]

A couple of observations.
Weight is a key factor and anything that adds weight has to be of value or it isn't worth the impact on the aircraft as a whole.

Any weapon less than 0.5 after mid 1943 is almost useless in the west, as the Luftwaffe were well protected against the LMG. As has been noted almost any spit from the Mk Vc onwards could carry 4 x 20mm and there is little doubt that this impacted its climb but had little impact on its speed or agility. There were no control or stability issues to be resolved.

Note summary of the Test Results of the Spitfire Vc with 4 x 20mm cannon:-
(i) The maximum rate of climb is 2,900 feet/minute at 13,400 feet. The time to 20,000 feet is 7.4 minutes, and the estimated service ceiling is 36,400 feet.
(ii) The top speed is 374 m.p.h. at 19,000 feet.
iii) There is no noticeable difference between the handling characteristics of this aeroplane and other Spitfire V types.
Spitfire Mk V Performance Testing

However against the aircraft they had to fight, the standard weapons of 2 x 20mm and 4 x LMG or 2 x 0.5 was more than sufficient

90 gallon drop tanks were routinely carried on the Spit IX on combat missions in the Med/Italian campaign without any issues

The Spitfire could easily carry the Hispano V if they were available and the Seafire III carried them as a standard fitting. Indeed the Hispano II and the Hispano V were interchangeable as they used the same mountings

 

[wuzak]

I'm sure it's been suggested before too, but in the previous discussion on Merlin 20 series (V-1650-1) powered Mustangs, particularly on the issue of actually proposing/testing such a prototype, the suggestion of acquiring a British manufactured Merlin for said testing didn't arise. Given the fact that it was being designed and manufactured to a British order (and the fact that both the XP-40L and the later experimental Merlin 60 powered Mustang used British manufactured engines for testing) it would have made plenty of sense for this to have been done. More so if the British themselves had requested such a configuration and supplied a test engine.

Such a request might have been the most likely way for an V-1650-1 powered Mustang to actually make it into production. (granted, with the timing of V-1650 production, the initial run of mustangs would still have to start with Allison powered models ... or have British Engines allocated to them -rather unlikely)

Hell, if they'd proposed that back during the NA-73 prototype design and construction phase, a Merlin engine might have been allocated to the project before the American V-1710 was even available. (due to US production allocation priority delays for the V-1710) Granted, that would be earlier than than the P-40 flew with a Merlin ... but rather less crazy than the likes of what the British later did reguarding jet developments. (admittedly different context, but as far as radical decisions, sacrificing the two flight worthy Goblin engines -and a third ground-test only one- was a much greater risk than providing a Merlin XX for testing in 1940, a couple months after the initial Hurricane Mk.II prototypes had received theirs)

Testing that early would still mean having to wait until late 1941 before V-1650s were available, or allocating british-built merlins to Mustangs ... which would also complicate logistics. (either shipping British engines to be installed in the US or shipping engineless airframes to the UK -removing the possibility of ferry flights)

Rolls-Royce suggested fitting either the Merlin XX or Merlin 61 in the Mustang. The former wasn't done, though it was discussed, while the latter was built as the Mustang X.

There was also some discussion that the Mustang X would be put in production - airframes would be shipped from the US to Britain where a Merlin 61 would be fitted and any airframe modifications performed.

 

[kool kitty89]

Rolls-Royce suggested fitting either the Merlin XX or Merlin 61 in the Mustang. The former wasn't done, though it was discussed, while the latter was built as the Mustang X.

There was also some discussion that the Mustang X would be put in production - airframes would be shipped from the US to Britain where a Merlin 61 would be fitted and any airframe modifications performed.

For the Merlin XX example to be worthwhile, procurment and testing of such would really have needed to take place much earlier than the Mustank X (or parallel developments with the Merlin 60 powered P-51 prototypes in the US) to be worthwhile. Namely before the first production Mustang examples were even being shipped to the UK.

 

[Edgar Brooks]

It seems to me there were control and stability issues that still needed to be solved.

Perhaps you might like to elaborate on that?

 

[Neil Stirling]

Using stainless steel stringers for strength) didn't carry this armament.


Huhh? Where do you get this from?


Neil

 

[drgondog]

The questions to be addressed to make daylight bombing by RAF feasible start with escort capability, or with airframe capability to outrun fighter interceptors.

The fact that LF3 with JG 2 and 26 was the primary defense is irrelevant - that is all that was required, Had RAF incursions during daylight become dangerous, the Luftwaffe would have drawn re-enforcements' from other fronts as required - just as they did beginning mid 1943 vs 8th AF.

The RAF defensive capabilities against fighter were less than B-17E/F/G or B-24D/H/J or B-26B/C capability - all of which required fighter escort to survive - at the target and all along the way.

The RAF bombers did not have turbo superchargers, limiting bomb ceilings below 20,000 feet which introduces another threat at a more dangerous threshold than their US counterparts - Flak. AAA is increasingly effective from the large caliber guns as the altitudes lower, and the additional 'small' flak such as 20/37/40mm flak becomes lethal below 10,000 feet.

Escort combat radius is influenced by two separate factors. First and most important is the internal capacity of fuel. Based on exhaustive American experience, the return range profile must account for a.) dropping external tanks, b.) engaging at full Military Power for up to 20 minutes, c.) returning in a straight line at optimal cruise speed, and d.) providing 30 minutes of loiter time as a contingency prior to landing.

If you use the Spitfire, the comparable internal fuel storage to escort RAF bombers to Berlin in 1941 would require approximately as much (actually more) as a P-51B with 85 gallon aft fuselage tank = 269 gallons. The 'more' factors include drag of the airframe as it relates to maximum miles per gallon at the operational bomber altitudes plus 0 to 5,000 feet, and capacity of external fuel storage as it affects both capacity and additional drag. The slipper tank design, if capable of the same 75 or 110 US gallon capacity could move the needle back slightly.

If you wish speed as the strategic alternative there is only one choice and that is the Mossie. IMO that selection points toward single or two ship formations to limit the intercept tracking and stretch German defenses. Single large formations, having no defensive firepower, seems foolish and in any case the loss rate will still be high. More effective? I don't see why the Mossie ability to deliver a bomb load better than a Halifax - on target - is improved unless the Mossie drops to the deck and makes its bomb run from there. In addition, Low altitude tactics influence fuel storage vs bomb load vs range calculations.

 

[gjs238]

The RAF bombers did not have turbo superchargers, limiting bomb ceilings below 20,000 feet which introduces another threat at a more dangerous threshold than their US counterparts - Flak. AAA is increasingly effective from the large caliber guns as the altitudes lower, and the additional 'small' flak such as 20/37/40mm flak becomes lethal below 10,000 feet.

Could they have implemented 2-stage supercharging?

 

[Shortround6]

They could have. They did on some late war Lancasters or Lincolns.

However the two stage engines only show up in small numbers part way through 1942 and you need them for the fighters. There were four squadrons of Spitfires with two stage engines at the time of Dieppe in Aug of 1942. Packard built 5 two stage engines in 1942. They built 7250 single stage engines. Obviously RR was making them first but you won't have enough to do anything until the very end of 1942.

Forget Berlin. It is about 360-370miles from Norwich to Hamburg and about the same from Norwich to Frankfurt. A P-51 with 184 US gallons internal and 150 gals in drop tanks was rated at a 460 mile radius. With 269 US gallons internal and no drop tanks it was rated at 375 miles. Now can you get enough fuel into a MK V Spit (not a IX or VIII although you can use the same tanks) with it's Merlin 45 engine AND have enough performance to fight the interceptors?
That is what you have in 1941-42.
Even an Early Mustang with the Allison swapped for a Merlin XX may have trouble. Even with just four .50 cal guns it could go 7300lbs or more with full internal tanks. About 800lbs heavier than a MK V Spitfire. It may be faster but climb and turn won't be as good. ANd MK V Spitfires weren't good enough in 1941/42.

 

[Edgar Brooks]

Can we get one thing clear? The lack of supercharging had nothing, whatsoever, to do with bombing from 18,000', it was a deliberate policy of the Air Ministry.
Flying above 20,000' (and the Lancaster I could go to 23,000') brings the aircraft into the zone of contrails, and four white trails in the glare of moonlight, would have been (as the Air Ministry put it ) like fingers beckoning to every nightfighter within range, and a certain death sentence.
The two-stage Merlin was originally planned for bombers (in daylight,) but became unnecessary at night, hence the availability for the Spitfire.

 

[Glider]

Is there any reason why people have such a hang up about bombing Berlin, when the industrial areas such as the Rhur would be at least as important

 

[Milosh]

Is that 23,000ft for a bomb laden Lancaster or a Lancaster with no bombs?

 

[pbehn]

Is there any reason why people have such a hang up about bombing Berlin, when the industrial areas such as the Rhur would be at least as important

I think purely because of the distance it represents, the Rhur could be bombed fairly accurately by night using the gee system from beginning 1942. Hamburg was target more easily identified at night, the problem was with targets deep in Germany away from the coast. These targets however are as hard to find by day under normal European cloud as they are at night. By the time the US became successful at daytime raids they had a huge recon capability which wasnt there in 1941/2.

 

[Greyman]

Is that 23,000ft for a bomb laden Lancaster or a Lancaster with no bombs?

Fully loaded.