An Allison V-1710 with a two-speed supercharger in 1942 (1 Viewer)

[ggiumarra]

Not entirely sure regarding the driving force to include 170-gal internal fuel in NA-73.

So on p. 129 of Bastard Stepchild (at least I think that is the page, I have in the Kindle Ed.) it states (May 1940) "the BPC [British Purchasing Commission] was already interested in increasing wing tankage to 170 gal." The context of that passage are changes the British want NAA to make to the Mustang design. Did I over interpret that?

On p. 150 it says "on the 24th of that month [September 1940] the BPC concluded negotiations for the second block of Mustang Is and executed contract A-1493 for 300 more Mustang Is, scheduled for final delivery in July 1942. The NA-83 as delivered included...increased fuel capacity to 90 gal in each wing." I drew the inference that the added 10 gal. capacity was at the request of the BPC since there was discussion of the contract just prior, but I see now that is not necessarily correct.

 

[ggiumarra]

I want to acknowledge the multiple earlier comments related to the practicability of operating Mustangs at Malta and perhaps near the Gazala area in June of 1942. There was a lot of good information in those posts (and some that did not seem particularly relevant, but often interesting nonetheless). I may make a more detailed response to them later but in short, the fact that there were few Mustang sorties flown in May is not necessarily indicative of an absolute impossibility of them being deployed to Malta and elsewhere the following month. I readily concede it raises credible doubts, and I will now add further qualifications in that regard (I already qualify it broadly speaking as I do anything that is counterfactual) when I finish writing that part of my study (which is the point I am at currently).

But it also could be the case that more aggressive steps were not taken earlier to discover and rectify the Mustang problems because there was no real perceived need in the short term, and thus no urgency to do so. I do not think that intruder missions by ACC a/c (as useful as they ultimately may have proved to be) were necessarily a high priority for the RAF in the spring of 1942. In that case it makes sense to be methodical about ramping up a new a/c in that role while you get the bugs worked out (incl. doctrinal ones). If there were indeed concerns about running through the limited inventory of Mustangs (it was probably understood that production was in danger of coming to a permanent end later in the year) then you would also want to take some time to work out how hard you wanted to go in that role, which again, I find it hard to believe anyone was seeing as more than an incremental benefit to the war effort at that particular moment. The focus was probably on primary ACC mission anyways which was direct support of ground forces in the UK in which case ironing out the sort of problems described also would likely lack any real urgency calling, again, for a methodical approach.

The dire situation at Malta was completely different. Relief was a priority at the highest level and came up at British War Cabinet meetings multiple times and involved considerable discussion. As I mentioned before, Churchill was busying himself with getting more day Beaufighters to Malta at this very time (I doubt he then knew anything significant about the Mustang I). In that context it would have made sense to push the envelope somewhat when it comes to a fighter like the Mustang I, with the range capabilities to be very helpful in the upcoming convoys, had anyone appreciated them, while at the same time pushing hard to make what fixes were absolutely necessary to make them "ready enough" in time.

The same arguments apply, even more so for Pedestal in August (after the near complete failure of Julius). I find it hard to believe, that defects in a compass, which should have been known at least as far back as February, if not earlier, could not be resolved within a few months at most had there been an urgent need to.

...Several instances of [Mustang] engine mount bolt structural failure in mid-March 1943 due to faulty heat treatment by NAA subcontractor.

It is also possible that there was an odd batch of defective compasses, just like the engine mount bolts mentioned in the quote above, that did not affect all Mustangs. Or possibly the compasses were functional, but the RAF preferred other ones? It does not mention a compass problem in the 1 May document I posted earlier, nor in the AFDU report later the same month, even though the latter document mentions the "cockpit too hot" issue as well, and of course, was the end product of intensive flight testing.

That said, I do grant that raising doubts to the objections is not nearly the same as completely rebutting them. The way I see it now is that it does seem highly unlikely that anything close to the higher numbers I was batting about earlier (up to 60) could have been made available in June. Even 6-8, however, could have been very useful since there was never enough PR Spitfires available and Marylands (also not that many on hand either and gas guzzlers, relatively speaking, to boot) had a bad habit of getting shot down and there were key moments in the June convoy operations (as in Pacific operations in 1942) when gaps in air reconnaissance created significant problems. 10 or even 20 Mustangs don't seem out the question, IMO. From the chart I posted above there seems to have been fewer than 60 LR Spitfire sorties for Harpoon and the claim was afterwards that no merchant vessels were hit while under the protection of Spitfires though there rarely if ever were more than 12 on station at any one time. The crucial miss, however, was first thing in the morning when the 5 Beaufighters were unable to protect the convoy leading to the loss of two merchantmen including the sole tanker. Even a relatively small number of Mustangs may have made a major difference.

With respect to space on Malta is concerned: there were at least 42 Hurricanes on Malta at the time, so some of them could have been displaced since from what I've read by this time they rarely see action.

As far as servicing Mustangs at a remote location - I just would point out on Midway the same month they had to handle B-26s and TBFs as well as B-17s that had just arrived, all of which (with the possible exception of the B-17s, which may have made a stop there earlier) were unfamiliar types to the ground crews there. Whatever the maintenance resource limitations of Malta, it's hard to think they were as great as on Midway atoll. Again, I am mainly talking about a window on Malta of 1 day before the convoys get within range of all Malta-based Spits (for recon) and the morning of the next day (for long-range convoy protection, even an handful of Mustangs would have been helpful compared to the Beaufighters which were unable at a critical moment to communicate with FC bc of the radio issue and also made themselves scarce once they were repeatedly shot at by the very convoy they were supposed to protect) - so not a large number of sorties; sorties after that are just a bonus until the next convoy comes, subsequent to which Mustangs are hopefully available enough to provide a significant supplement to the Spits.

Fwiw, here are are some of my notes for Caz Boyer, Beaufighter at War (London: Allan, 1976) which I made reference to before:

p. 48 May 1942 twelve Beaufighter crews ordered to Lyneham England to prep for deployment (2 more joined later). The aircraft were from shadow factories and showed poor workmanship ("net result – top speed 30 knots less than our 'old' Beaus, and obviously an adverse effect on endurance, which would be of vital importance to us on our two long hops…"). Departed England for Gibraltar on June 3 (4.5 hour flight). Departed Gibraltar for Malta on June 10 – one a/c missing. June 14 four Beaufighters protected the eastbound convoy for 1.5 hours before dusk (1 Ju 88 claimed shot down). Walked in on a briefing of Spitfire pilots and was shocked to hear them being told that all twin engined a/c were hostile.​

I would repeat that there were some complaints registered on Malta about the poor state the Beaufighters arrived in, so that is consistent with what I was saying above that in an emergency situation military leaders might accept a level of readiness they normally would not.

(Wait, did I say "in short"?)

 

[SaparotRob]

"informative" plus punchline equals "winner.

 

[drgondog]

So on p. 129 of Bastard Stepchild (at least I think that is the page, I have in the Kindle Ed.) it states (May 1940) "the BPC [British Purchasing Commission] was already interested in increasing wing tankage to 170 gal." The context of that passage are changes the British want NAA to make to the Mustang design. Did I over interpret that?

No, but my comment was directed more to the fact that AAC was already responding to BPC requests for self sealing tanks and armor plate for P-40, P-38 and P-39. What I'm saying is that NAA was very cognizant of Mat.Cmd. directions away from 1938 standard of 100-gal+ internal fuel for pursuit. I'm equally sure that BPC steered NAA away from the smaller wing to improve speed (P-509/NA-73X as in existence in early April). Internal fuel had to be a consideration.

On p. 150 it says "on the 24th of that month [September 1940] the BPC concluded negotiations for the second block of Mustang Is and executed contract A-1493 for 300 more Mustang Is, scheduled for final delivery in July 1942. The NA-83 as delivered included...increased fuel capacity to 90 gal in each wing." I drew the inference that the added 10 gal. capacity was at the request of the BPC since there was discussion of the contract just prior, but I see now that is not necessarily correct.

This is entirely subjective but I have been in preliminary design discussions in which invariably the question of 'more or less fuel tankage' arise.

What I would offer is that RAF/BPC were only entities that NAA worked so closely with to frame a Specification - at least through the Korean War. For example, NAA delivered the Xp-51B as a 'modification' to NA-91 rather than go through the spec process with Wright Field. The XP-51F and P-51D-NA were both letter agreements rather than Specification for submittal to Wright Field.

So, the answer to your assumption is 'maybe', not 'no'. At the very least I have zero sources rergading THE specific entities driving 156-gal of P-509 to 170-gal of NA-73 XP-51 (Mustang I).

 

[Shortround6]

The same arguments apply, even more so for Pedestal in August (after the near complete failure of Julius). I find it hard to believe, that defects in a compass, which should have been known at least as far back as February, if not earlier, could not be resolved within a few months at most had there been an urgent need to.

The P-39s that were tried in England in the fall of 1941 had compass problems, most notably when they fired the .50 guns.
Curtiss Tomahwk Is had so much trouble with their .50 cal guns in Spring/Summer of 1941 that the crews figured that the effective armament was the four .303 or .30 cal guns.
Curtiss Kittihawks had trouble with their .50 cal guns to start with.
Wildcats had troubles with their .50 cal guns.
Just about everybody had troubles with radios. P-47s in 1943 at start of operations had to take out their radios and replace them with British radios. At least the P-47 guns were working in the summer of 1943
The American .50 cal got a lot better or rather installations did or both.

The Beaufighter, having entered combat in the fall of 1940, was more of a known quantity. There could always be surprises in different climates which is why they did tropical trials.

In the Summer of 1942 the Mustang is that the British had held 180 US gallons of fuel, with no provision for extra fuel.
The Kittihawks could hold 197 US gallons with the common 52 gal drop tank.
They both used the same engine.
The Mustang was faster. Until they got operational experience with the Mustang (combat missions in Europe?) actual usable range might have been questionable. Turns out it was better than the P-40 but when was the actual knowledge and not promised that it would be significantly better than the P-40 gained?
Beaufighters had not only range, they had the 2nd crewman for radio work and navigation that was supposed to help for flying over water and two engines.

For a lot of these situations, what they knew in Dec 42/Jan 43 was different than what they knew in July 1942 let alone what then knew in March of 1942.

This also applies to the air war over France/Germany/low countries in 1942.
The RAF had to be seen as 'doing something', mostly for political/propaganda purposes. Stalin was pushing for a 2nd front and he was not talking about 3-4 divisions mucking around in North Africa.
Dieppe really brought home to the British and America that they were not ready to invade Europe.
That left air attack. How that should have been done in late 1942 or early 43 with a lack of suitable aircraft?

 

[andy1967]

The P-39s that were tried in England in the fall of 1941 had compass problems, most notably when they fired the .50 guns.
Curtiss Tomahwk Is had so much trouble with their .50 cal guns in Spring/Summer of 1941 that the crews figured that the effective armament was the four .303 or .30 cal guns.
Curtiss Kittihawks had trouble with their .50 cal guns to start with.
Wildcats had troubles with their .50 cal guns.
Just about everybody had troubles with radios. P-47s in 1943 at start of operations had to take out their radios and replace them with British radios. At least the P-47 guns were working in the summer of 1943
The American .50 cal got a lot better or rather installations did or both.

The Beaufighter, having entered combat in the fall of 1940, was more of a known quantity. There could always be surprises in different climates which is why they did tropical trials.

In the Summer of 1942 the Mustang is that the British had held 180 US gallons of fuel, with no provision for extra fuel.
The Kittihawks could hold 197 US gallons with the common 52 gal drop tank.
They both used the same engine.
The Mustang was faster. Until they got operational experience with the Mustang (combat missions in Europe?) actual usable range might have been questionable. Turns out it was better than the P-40 but when was the actual knowledge and not promised that it would be significantly better than the P-40 gained?
Beaufighters had not only range, they had the 2nd crewman for radio work and navigation that was supposed to help for flying over water and two engines.

For a lot of these situations, what they knew in Dec 42/Jan 43 was different than what they knew in July 1942 let alone what then knew in March of 1942.

This also applies to the air war over France/Germany/low countries in 1942.
The RAF had to be seen as 'doing something', mostly for political/propaganda purposes. Stalin was pushing for a 2nd front and he was not talking about 3-4 divisions mucking around in North Africa.
Dieppe really brought home to the British and America that they were not ready to invade Europe.
That left air attack. How that should have been done in late 1942 or early 43 with a lack of suitable aircraft?

Interesting point you mentioned about the Air War over France/Germany/Low Countries in 1942.The Imperial War Museum has this to say about the time period 41/42.

 

[MiTasol]

A couple of links that may interest those collecting information on Mustang ops can be found at https://digitalcollections.museumof...ccess=0&has=W10=&bid=0&meta=W10=&metainc=W10=

I saw several items on early Mustang ops last week but with over 400 pages to search only found these today using a different search criteria. There is no search function on the site so you must use one of their pre-programmed searches.

https://digitalcollections.museumofflight.org/nodes/view/3011?type=all

 

[ColFord]

But it also could be the case that more aggressive steps were not taken earlier to discover and rectify the Mustang problems because there was no real perceived need in the short term, and thus no urgency to do so.

The issues with the early Mustangs were being found in the usual RAF practices for the introduction of a new aircraft type into service. Trial flights and reports by AFDU, AA&EE, RAE, then feedback from the first units to receive them and operate them in other than a trials environment. Once an issue is identified during a trials flight or Squadron flying, it then has to be determined if the issue is with the specific aircraft being flown it has shown up in, or more wider spread. Hence why in a number of the AA&EE reports, they detail addition of another aircraft of the same basic type, sometime later production batch, to refly the trials and see if the same issue presents. Issue identified and confirmed as wide spread, then investigation into the cause of the issue and once the actual cause is known rather than suspected, identify potential solution(s). In this phase there would be back and forth between the Air Ministry, the aircraft suppliers representatives in the UK (who would in turn be communicating back to their head office in the USA who would investigate, potentially contact sub-contractors if the issue related to a supplier item, arrive at potential solutions, communicate, etc). Conduct trials on identified solution(s), rinse and repeat until issue is fully resolved or mitigated to an acceptable level. You throw into that, potential for discussion to identify who is responsible for identifying the solution and then implementing it, (plenty of back and forth between ACC, Air Ministry, MAP, NAA), then you have to get the parts, resources, priority for the parts and resources allocated, and actually get the solution in place across all the aircraft already received and implemented on those still arriving into the country - negotiate the change in scope of works with the contractors doing the reassembly at Abbotsinch and Speke and make sure they get the required parts and technical information required.

Throw into that, the place of ACC in the pecking order at the time, below Fighter Command, below Bomber Command, below Coastal Command, and the competing demands of all the commands on available resources.

The compass issue, was resolved by installing a RAF specification P-8 compass and rewiring. Like the P-39 and P-40 Tomahawk, the original compass showed wild deviation and variations in reading whilst the nose 0.50in HMGs were fired and after. Part of the problem was thought to be electrical fields being generated in the nose gun firing circuits and in particular the synchroniser gear, combined with large moving metal mass of the breech and fed mechanisms. Added into that was the physical movement of metallic mass in the form of the ammunition, from the ammunition tanks in the nose in alignment with the staggered breeches of the nose guns, with the spent cases and links being ejected back into a holding tank that sat right next to the firewall.

For the problems to be resolved any faster requires significant application of high level political will, and allocation of resource priorities at a time where there were many competing priorities home and abroad. The ACC Squadrons also saw in the first months on 1942, a large number of experienced aircrew and ground crew being posted out to meet demands from overseas (primarily MTO and CBI) and also Bomber Command at home. So they were in a cycle of new aircraft, training up new aircrew and groundcrew, whilst increasing their rates of operational flying and activities that lasted pretty much to the end of 1942. Then in November-December 1942 losing three Squadrons of trained personnel to the MTO as part of the contributions for Operation TORCH.

 

[Geoffrey Sinclair]

Some of the June 1942 Beaufighter sent to the Mediterranean.
VIc built by Bristol Weston
X8030, 8033, 8034, 8035, 8063, 8070, 8076 (missing after departing Gibraltar), 8077, 8078,
Ic built by Fairey,
T4934, 4990, 5006, 5027 (missing after departing Gibraltar)
VIc built by Fairey
T5136 (crashed in Spain), T5138,

Operation Calendar, 46 Spitfires arrived 20 April 1942, from 20 to 26 April, 12 Spitfires lost, 23 damaged, along with 5 Hurricanes lost and 7 damaged, 60 more Spitfires on 9 May, during May there were 30 Spitfires lost, 28 damaged.

Christopher Shores notes to 13 June 1942, 213 Spitfire arrivals, 52 lost, 16 crash landed, 35 lost on ground, 95 currently serviceable and that to maintain 6 Spitfires above both convoys at all times left 12 available for defence of Malta. The records of the operations say 222 fighters sent, 215 arrived. Date is usually departure from Gibraltar except for USS Wasp operations.

Date Sent / Malta Ship Code
6-Mar-42 15 / 15 HMS Eagle Spotter/Quarter
20-Mar-42 9 / 9 HMS Eagle Picket I/Scantling
27-Mar-42 7 / 7 HMS Eagle Picket II/Scantling
20-Apr-42 47 / 46 USS Wasp Calendar/Newman
9-May-42 17 / 17 HMS Eagle Bowery/Oppidan
9-May-42 47 / 43 USS Wasp Bowery/Oppidan
17-May-42 17 / 17 HMS Eagle LB/Hansford
2-Jun-42 31 / 29 HMS Eagle Style/? (2 more shot down over Gozo)
8-Jun-42 32 / 32 HMS Eagle Salient/Maintop

12 June MW4 left Gibraltar, MW11 left Egypt on 11 and 12 June.

I want to acknowledge the multiple earlier comments related to the practicability of operating Mustangs at Malta and perhaps near the Gazala area in June of 1942. There was a lot of good information in those posts (and some that did not seem particularly relevant, but often interesting nonetheless).

The comments included objections, the reply is an unspecified amount is good information about something, and others not relevant. Which parts are accepted as truthful,? They seem more noted than acknowledged.

I may make a more detailed response to them later

This response has been offered several times now.

but in short, the fact that there were few Mustang sorties flown in May is not necessarily indicative of an absolute impossibility of them being deployed to Malta and elsewhere the following month.

As the P-51 was in existence in June 1942 some could always have arrived, but under this rule so could the Typhoon, P-38F, P-40F, P-47B amongst others, some would be rush jobs. The requirement is arrival with trained crews and support to enable days of operations.

P-38F first production February 1942, first operation in Britain 29 August 1942, attempted interception, first offensive sorties 2 September
P-47C first production September 1942, first operation 10 March 1943, then withdrawn while issues were worked on, next operation 8 April.

I readily concede it raises credible doubts, and I will now add further qualifications

Doubts are not listed, instead "could be the case", "I do not think", "If there are concerns", "I find it hard to believe", "likely lack", "It is also possible", "it would have made sense", "should have been known", "it's hard to think", none of which is evidence.

If there were indeed concerns about running through the limited inventory of Mustangs (it was probably understood that production was in danger of coming to a permanent end later in the year) then you would also want to take some time to work out how hard you wanted to go in that role,

So the fact there was a known limit on the numbers going to be available is a reason they were not available at the required time, which document says numbers are finite so do not rush them into service?

The focus was probably on primary ACC mission anyways which was direct support of ground forces in the UK in which case ironing out the sort of problems described also would likely lack any real urgency calling, again, for a methodical approach.

In January 1942 the RAF wants all its tactical reconnaissance units to use Mustangs, but the idea is this still means a lack of real urgency in making the type fit for combat? Nor does the widespread May 1942 understanding about how good the airframe is? And fixing the Allison version would be a good start towards the Merlin version?

In that context it would have made sense to push the envelope somewhat when it comes to a fighter like the Mustang I, with the range capabilities to be very helpful in the upcoming convoys, had anyone appreciated them, while at the same time pushing hard to make what fixes were absolutely necessary to make them "ready enough" in time.

All you need is foresight, like say knowing Malta could hold so building up food stocks pre war or sending another 6 or more ships in the 1940/41 convoys that made it through and that the USSR would survive into 1942 thereby eliminating the possibility the Germans undertake major operations against Malta in early 1942 while waiting for the better weather to attack Britain. There is also better unloading of Talabot, Pampas and Breconshire in March 1942. How about a little more force in Crete in 1941 resulting in the parachute assault failing?

It is also possible that there was an odd batch of defective compasses, just like the engine mount bolts mentioned in the quote above, that did not affect all Mustangs. Or possibly the compasses were functional, but the RAF preferred other ones?

Many things are possible but the idea is to provide evidence. Firing the armament in the P-39 set up magnetic fields that made a mess of the compass, same in the Mustang, passing metal through electric fields tends to do that.

Even 6-8, however, could have been very useful ... 10 or even 20 Mustangs don't seem out the question

The numbers in existence say it is quite possible, whether that translates to an effective fighting force is another matter. Spare parts supply is required as well as trained pilots and ground crew.

I just would point out on Midway the same month they had to handle B-26s and TBFs as well as B-17s that had just arrived, all of which (with the possible exception of the B-17s, which may have made a stop there earlier) were unfamiliar types to the ground crews there.

Most obvious point, how many sorties did the types do before and on the first day of the Midway battle? The B-17 arrived 30 and 31 May, the TBF and B-26 similarly, B-17 9 sorties to attack a convoy in 3 June. Next comes the idea the B-17 at least did not ferry in some of their ground staff.

Whatever the maintenance resource limitations of Malta, it's hard to think they were as great as on Midway atoll.

Open supply line at Midway, limited number of sorties required. Lots of bomb damage and continuing air raids at Malta.

Beaufighters which were unable at a critical moment to communicate with FC bc of the radio issue and also made themselves scarce once they were repeatedly shot at by the very convoy they were supposed to protect)

The RAF deploys for the first time a new single engine type whose wings look like the Fw190 and it will not be shot at?

I would repeat that there were some complaints registered on Malta about the poor state the Beaufighters arrived in, so that is consistent with what I was saying above that in an emergency situation military leaders might accept a level of readiness they normally would not.

235 squadron sent 14 crews to Malta on 2 June 1942, ferrying Beaufighters, "Said to be poorly built, with overlapping joints in the fuselage and wing surfaces instead of butt joints, inspection covers not fitting and screw heads standing proud of the surface" Ferry flight began on 2 June. Malta reported the armament was dirty, some link chutes not wired up, US 20mm ammunition, guns and sights possibly not harmonised, also radio issues, the X serials had been built in April and May 1942, as were the Fairey VIC, the Ic from late 1941/early 1942.

See the complaints USS Wasp registered about the state of the Spitfires loaded. Malta about the quality of new pilots.

(Wait, did I say "in short"?)

In theme yes, the what if stands because the P-51 existed at the time, with things like reports of compass problems given "possible" answers.

Code breaking made the Axis anti shipping operations more effective in June 1942, just as Ultra did for the allies.

 

[MiTasol]

Smithsonian have these in their catalog record. Some may find of interest.

 

[Steamed_Banana]

Couple of comments re: P-51 vs P-39 and P-40 and P-38G and P-47B
Tactical Trails at Eglin Proving Ground Aug 7 -Nov 7, 1942
Summary statement "This airplane (P-51-NA) superior to all other types up to 15,000 feet"
Below 15000 feet:
Speed - superior to all types
Climb - superior to P-39D, P-40F, P-47B
Turn - equal to P-40, P-39, better than P-38F and P-47B
Roll - slightly inferior to P-40F, superior to P-39, P-38 and P-47.
Dive - better acceleration and top dive speed than all others tested.

Note, the P-51 was 400 pounds heavier than XP-51/Mustang I/A-36/P-51A due to the 4x20mm cannon inst'l and was 'draggier due to both the cannon installation and also induced drag due to higher weight. Also note that the P-40 remained a 'better roller' than all versions of the P-51, below 250-280mph TAS but all versions of P-51 could extend rather than fight due to much higher speed envelope for both level flight and dive. Only the P-47B was equal in dive, but also structurally deficient at near terminal dive speeds - but it was lighter than the P-47B/C with same HP until water injection introduced in the D-11.

Notes about P-51 design issues leading to structural failures:
Loose latches on main gear door fairing, which resulted in opening due to aero loads.
Inadequate up-lock for main gear, causing gear to crash through the fairing door in high g/high aero loads,
Ammo door failure due to very high speed aero induced loads.
Empennage failure due to severe asymmetric loads with several inputs causing the failure due to large rudder deflections in roll and coupled with yaw and high prop vortex strength.
Several instances of engine mount bolt structural failure in mid-March 1943 due to faulty heat treatment by NAA subcontractor.

Fixes:
Beef up latches and up-lock.
Stiffen ammo door.
Introduce dorsal fin and reverse rudder boost tab, then change angle of incidence for H.Stab and introduce metal elevators.
Introduce improvements to contractor part QA for critical components.

This was an optimistic report which I think was trying to save the P-51 project (a laudable goal, as it turns out), but it was not borne out by combat outcomes and some data points were just wrong.

The P-39, P-40, and P-38G could all out turn the early P-51, both in terms of sustained turn (turn times) and instantaneous or high-G turn. Of these, only the P-47 had a higher stall speed, and the P-51 fell off in high G turns.

The little rolling problem which is somewhat glossed over here turned out to be a big problem as well. Here the P-40 was the best, which probably had a lot to do with how it's operational history went. The P-47 rolled well at high altitude (above 20,000 ft). I am not sure if the P-38G had the boosted ailerons yet, though even with these 'roll reversal' was still an issue for them. The P-51 had serious roll rate issues which were corrected with the P-51B (I have learned, this was not just a matter of 'rigging' the ailerons but required a structural change to the wing).

In combat both in North Africa and the CBI the (Allison) P-51 did not have very good outcomes against enemy fighters, especially compared to the P-40 and P-38G, though of the P-40s, only the P-40F/L was considered sufficiently high performance to contend with the German and Italian fighters by mid 1942 (i.e. not the Allison types). In the CBI the P-40s of all types were able to perform well against the JAAF fighters, the P-51A considerably less so. The P-51 units suffered at the hands of Ki-43-IIs.

 

[Steamed_Banana]

Smithsonian have these in their catalog record. Some may find of interest.
View attachment 877208

View attachment 877209


View attachment 877210

Damn! How do we get these!? Do you have to go on-site?

 

[Shortround6]

This was an optimistic report which I think was trying to save the P-51 project (a laudable goal, as it turns out), but it was not borne out by combat outcomes and some data points were just wrong.

The P-39, P-40, and P-38G could all out turn the early P-51, both in terms of sustained turn (turn times) and instantaneous or high-G turn. Of these, only the P-47 had a higher stall speed, and the P-51 fell off in high G turns.

The little rolling problem which is somewhat glossed over here turned out to be a big problem as well. Here the P-40 was the best, which probably had a lot to do with how it's operational history went. The P-47 rolled well at high altitude (above 20,000 ft). I am not sure if the P-38G had the boosted ailerons yet, though even with these 'roll reversal' was still an issue for them. The P-51 had serious roll rate issues which were corrected with the P-51B (I have learned, this was not just a matter of 'rigging' the ailerons but required a structural change to the wing).

In combat both in North Africa and the CBI the (Allison) P-51 did not have very good outcomes against enemy fighters, especially compared to the P-40 and P-38G, though of the P-40s, only the P-40F/L was considered sufficiently high performance to contend with the German and Italian fighters by mid 1942 (i.e. not the Allison types). In the CBI the P-40s of all types were able to perform well against the JAAF fighters, the P-51A considerably less so. The P-51 units suffered at the hands of Ki-43-IIs.

There is problem with using combat results to evaluate the P-51/P-51A aircraft vs other American aircraft.
There weren't enough built and issued to get a good statistical base.
Of the 150 P-51 aircraft 93 went to the British leaving 57 for US use and most (55?) were converted to F-6A recon planes. These do not start to see action until April of 1943.
Photo recon missions were usually single or paired flights with the goal of getting the photos back. Not engaging in air-to-air combat or strafing.
Of the 310 P-51As built, 50 were given to the British as pay back for the 57 Mustang IA's that the US kept.
35 P-51As were converted to F-6B photo recon planes. Most of these were based out of England.
This leaves 225 Allison powered Mustang fighters in US service, not including aircraft used for experiments and training. that is under 50% of the numbers of A-36s. This is one reason that some groups used a mix of A-36s and P-51As. There weren't enough P-51As to really equip entire groups with.

Your timeline is also somewhat off.
The combat trials that started in Aug 1942 had nothing to do with the initial P-51A order which was placed on June 23rd 1942. This order was for 1200 aircraft and was cut to 310 in Dec 1942. Production in any country was always months or year behind orders. The Last British Mustang I left the production line July 1942 and these were followed by the Mustang IA (P-51) then by the 500 A-36s in starting in Sept/Oct 1942.
The trial report quoted has the trials finishing on Nov 1st 1942 although the report itself is finished/dated Dec 1942.
On Aug 26th 1942 NAA got a contract for 400 P-51B-1NA aircraft, this was later modified with 1350 aircraft added to the order.
In Dec 1942 the order for the 1200 P-51As placed in June was amended to 310 aircraft with the remainder to be completed as P-51Bs.
On Oct 8th NAA got a contract for 1350 P-51C aircraft for it's Dallas plant.

Unless the fighter trials at Eglin had shown the P-51s to be truly flawed there is no question that the trials were any part of an attempt to save the P-51 project.
Before the trials were even finished and well before the report was finished/signed, NA had contracts for almost 3000 P-51s after the A-36s.

 

[Steamed_Banana]

There is problem with using combat results to evaluate the P-51/P-51A aircraft vs other American aircraft.
There weren't enough built and issued to get a good statistical base.
Of the 150 P-51 aircraft 93 went to the British leaving 57 for US use and most (55?) were converted to F-6A recon planes. These do not start to see action until April of 1943.
Photo recon missions were usually single or paired flights with the goal of getting the photos back. Not engaging in air-to-air combat or strafing.
Of the 310 P-51As built, 50 were given to the British as pay back for the 57 Mustang IA's that the US kept.
35 P-51As were converted to F-6B photo recon planes. Most of these were based out of England.
This leaves 225 Allison powered Mustang fighters in US service, not including aircraft used for experiments and training. that is under 50% of the numbers of A-36s. This is one reason that some groups used a mix of A-36s and P-51As. There weren't enough P-51As to really equip entire groups with.

We can always debate to infinity about what qualifies as a valid statistical sample, but in the area where the Mustangs were active, there were other units flying almost the same missions against the same enemies and with different outcomes, not just once or twice but over and over again over substantial period of time: P-40s, P-38s, Hurricanes, Mohawks, Spitfires.

Sometimes it was in the same units, for example 23rd and 51st FG were flying P-40s and P-51s at the same time, sometimes against the same targets. Outcomes were substantially different. Numbers were small but there were repeated examples of sorties against identical targets over the course of more than a year.

Your timeline is also somewhat off.
The combat trials that started in Aug 1942 had nothing to do with the initial P-51A order which was placed on June 23rd 1942. This order was for 1200 aircraft and was cut to 310 in Dec 1942. Production in any country was always months or year behind orders. The Last British Mustang I left the production line July 1942 and these were followed by the Mustang IA (P-51) then by the 500 A-36s in starting in Sept/Oct 1942.
The trial report quoted has the trials finishing on Nov 1st 1942 although the report itself is finished/dated Dec 1942.
On Aug 26th 1942 NAA got a contract for 400 P-51B-1NA aircraft, this was later modified with 1350 aircraft added to the order.
In Dec 1942 the order for the 1200 P-51As placed in June was amended to 310 aircraft with the remainder to be completed as P-51Bs.
On Oct 8th NAA got a contract for 1350 P-51C aircraft for it's Dallas plant.

So by this timeline the report coincides with the development and initial production planning for the Merlin P-51, which validated the project.

Unless the fighter trials at Eglin had shown the P-51s to be truly flawed there is no question that the trials were any part of an attempt to save the P-51 project.
Before the trials were even finished and well before the report was finished/signed, NA had contracts for almost 3000 P-51s after the A-36s.

I don't see how this rules it out seeing as it was basically simultaneous to the military recognizing the potential of the type.

Anyway, the fact is the P-51 was as we all know, substantially faster than any other US fighter type, and remained faster as new versions of other types were developed, but it also had some significant issues. You are always on about overweight fighters - the P-51 was overweight, and weighed almost 800 lbs more than a P-39D, 300 lbs more than a P-40E, and 600 lbs more than an F4F-4. It took a much better engine to bring out it's real advantages (even though the Merlin types were even heavier, ~1,000 lbs heavier than the Allison type!)

 

[drgondog]

This was an optimistic report which I think was trying to save the P-51 project (a laudable goal, as it turns out), but it was not borne out by combat outcomes and some data points were just wrong.

No, the pilots at Eglin had no skin in the game, it was the first time the Mustang had been thoroughly tested as Wright Field was 'disinterested'. Operational suitability tests were not charm school and if you read the report they are openly critical regarding too much weight, etc - but the summary was founded on the individual comparisons of each pilot flying each aircraft.

The P-39, P-40, and P-38G could all out turn the early P-51, both in terms of sustained turn (turn times) and instantaneous or high-G turn. Of these, only the P-47 had a higher stall speed, and the P-51 fell off in high G turns.

The P-38G had fowler flaps but no boosted ailerons and lost energy faster that all the other compared fighters in sustained turns. Where the P-38 could actually turn 'with' the other fighters was at low speed by a skilled pilot managing different throttle setting in the turn. The phrase was 'equivalent to' when compared to P-40 and better than the P-39 and P-47 up to FTH vs P-47. Pilot skill is always a factor.

All 'fell off' in high speed turns, similar to FW 190 and Bf 109. The high wing always had more drag requiring lot of rudder to track and usually the high wing stalled first. Wing Loading was primary factor for both climb and turn, but the P-51 at middle to high speeds capitalized on low cooling drag, better overall aerodynamics to compensate for slightly higher wing loading. There is also the matter that the P-51A was 400+ plus lighter than the P-51-NA with 4x20mm guns and ammo.

The little rolling problem which is somewhat glossed over here turned out to be a big problem as well. Here the P-40 was the best, which probably had a lot to do with how it's operational history went. The P-47 rolled well at high altitude (above 20,000 ft). I am not sure if the P-38G had the boosted ailerons yet, though even with these 'roll reversal' was still an issue for them. The P-51 had serious roll rate issues which were corrected with the P-51B (I have learned, this was not just a matter of 'rigging' the ailerons but required a structural change to the wing).

Nope. The P-40 was a better roller at low to medium speeds vs P-51B, and there were no 'structural' issues associated with increasing aileron throw to +/- 15 degrees but the B-5 and Subs Did change the design to 3 hinge points from two.

The P-47C and early D Did roll well, and as well as the P-40, but lost that advantage when they hung pylons on for the 150gal drop tanks.

The P-51B and P-38J with boosted ailerons were very close to the same turn rate with slight advantage to the P-38J depending on pilot skill. Both out turned the P-47D

In combat both in North Africa and the CBI the (Allison) P-51 did not have very good outcomes against enemy fighters, especially compared to the P-40 and P-38G,

In Africa, only the A-36 was operational with an Allison possessing a FTH of 5,500 feet. Despite that the air to air ratio was close to 1:1. The P-38F and G 'suffered' against skilled Axis pilots, ditto the P-40F - but the 52nd FG converted to Spitfires for very good reasons compared to the P-40

though of the P-40s, only the P-40F/L was considered sufficiently high performance to contend with the German and Italian fighters by mid 1942 (i.e. not the Allison types). In the CBI the P-40s of all types were able to perform well against the JAAF fighters, the P-51A considerably less so. The P-51 units suffered at the hands of Ki-43-IIs.

Define 'not very well' and 'suffered'. I do not have a source enabling a comparison of air to air victory credits of the P-40 in either CBI or MTO, for either RAF or AAF. Do You? you would have to do a deep dive in MACRs and Victory Credits - both of which were sparse n CBI and MTO.

 

[MiTasol]

Damn! How do we get these!? Do you have to go on-site?

Go to https://sova.si.edu/record/nasm.xxxx.0428/ref8796?t=G&q=*:* and locate the file you are interested in and beside it you will see

I expect that will provide a link to who to contact. I have not tried this as I have my own contact there.

 

[Steamed_Banana]

In Africa, only the A-36 was operational with an Allison possessing a FTH of 5,500 feet. Despite that the air to air ratio was close to 1:1.

That would be claims not actual losses.

The P-38F and G 'suffered' against skilled Axis pilots, ditto the P-40F - but the 52nd FG converted to Spitfires for very good reasons compared to the P-40

The US P-40 units in the MTO did much better than 1:1 and many of the US FG flying P-40s (33rd, 57th, 79th, 324th and 325th) had the best records in Theater for US fighter units through mid 1943, and were still doing well through Anzio in early 1944.

The P-38F and G did have a lot of problems in Theater in the first few months of 1943 but seem to have adjusted and were basically holding their own by mid-year.

Define 'not very well' and 'suffered'. I do not have a source enabling a comparison of air to air victory credits of the P-40 in either CBI or MTO, for either RAF or AAF. Do You? you would have to do a deep dive in MACRs and Victory Credits - both of which were sparse n CBI and MTO.

I have Christopher Shores books (Mediterranean Air War series and Bloody Shambles series) that go through the operational histories day by day with the losses on both sides. P-51A like 1st Air Commando Group routinely did worse than 1:1 in the CBI against Ki-43s. You'd have to do your own totals but I've posted operational histories for a few weeks at a time which can give you a pretty good idea.

 

[Steamed_Banana]

Go to https://sova.si.edu/record/nasm.xxxx.0428/ref8796?t=G&q=*:* and locate the file you are interested in and beside it you will see
View attachment 877509
I expect that will provide a link to who to contact. I have not tried this as I have my own contact there.

Thanks!

 

[ColFord]

Of the 150 P-51 aircraft 93 went to the British leaving 57 for US use and most (55?) were converted to F-6A recon planes. These do not start to see action until April of 1943.
Photo recon missions were usually single or paired flights with the goal of getting the photos back. Not engaging in air-to-air combat or strafing.
Of the 310 P-51As built, 50 were given to the British as pay back for the 57 Mustang IA's that the US kept.

Confirmed by both the Air Ministry Form 78 and other documentaton, and the US records, the UK received 92 NA-91 P-51s, the US retained 58. Of the 58, two allocated to NAA for the XP-51B program, remainder initially retained for USAAF, one of those later transferred to USN.

The low level tactical reconnaissance sorties flown by the RAF Squadrons operating the Allison engine Mustangs, were usually by pairs. Lead and a No.2 'weaver', the lead would be responsponsible for leading the pair, navigation and would normally be the designated camera carrying aircraft. The 'weaver' their primary role was to follow the lead, and maintain the lookout for enemy fighters. Depending on the experience of the pilots, and depending on the length of the sortie and number of targets to be photographed, the 'weaver' might also carry a camera, and there could be a pre-briefed switch of the lead and weaver roles at a given point during the sortie. It was considered that if during the sortie one of the pair should go unserviceable and have to return to base, then both should abort the sortie and return together. It was not the usual operational doctrine to have an aircraft proceed solo, except in exceptional circumstances. If aircraft in a pair became separated by weather or enemy action, then they usually had a couple of pre-arranged rejoin locations along their originally planned route, somewhere usually easy to navigate to and find and usually on the path back to base.

The RAF did use its Allison engine Mustangs for ground strafing of targets of opportunity or when engaged in purely offensive operations - in 1942 and 1943 a percentage of their operations were Rangers and Rhubarbs, attacking a range of targets in occupied France, Belgium and the Netherlands. This was largely focussed on attacks on railway engines and rolling stock, canal transportation and enemy military vehicles and installations. From late 1943 the focus shifted more to the photographic sorties, a combination of both requirements in the lead up to D-Day and the campaign against the German V weapon sites in northern France. After D-Day there were restrictions placed on the RAF Tac/R units to avoid combat and they were prohibited from offensive action, defensive only, the primary focus being on getting back to base with both the visual observations made by the pilots and the photographic coverage. It was some months after D-Day that prohibition was lifted, but there were various periods where the 'offensive spirit' of the pilots had to be restrained as the intelligence they were gathering was of higher value than any physical damage they might do to the enemy. From early 1945 onwards, the instructions changed somewhat, the reconnaissance still had priority, but they had more free rein to attack fleeting targets of opportunity that were out in the open, especially harassing the enemy when they were in retreat.

The 50 NA-99 P-51A provided by the US to the UK were part pay back for the 58 NA-91 P-51 retained by the US. The 'balance' of the pay back was made up in supply of additional new Allison V-1710-39 F3R engines (required a special production batch}, supply of extra engine overhaul kits/parts and a range of other required spares and components for the RAF's Mustang I and IA aircraft.

 

[drgondog]

That would be claims not actual losses.

Yes and the converse is true regarding Axis claims.

The US P-40 units in the MTO did much better than 1:1 and many of the US FG flying P-40s (33rd, 57th, 79th, 324th and 325th) had the best records in Theater for US fighter units through mid 1943, and were still doing well through Anzio in early 1944.

Prove it. Let me know when you have the victory credits awarded, and the MACRs in hand to analyze the losses. Are you also stating that the 31st and 52nd flying Spitfires in 1943 were below he P-40 units?

The P-38F and G did have a lot of problems in Theater in the first few months of 1943 but seem to have adjusted and were basically holding their own by mid-year.

Pilots and tactics adapted to force tendency to 'dogfight'.

I have Christopher Shores books (Mediterranean Air War series and Bloody Shambles series) that go through the operational histories day by day with the losses on both sides. P-51A like 1st Air Commando Group routinely did worse than 1:1 in the CBI against Ki-43s. You'd have to do your own totals but I've posted operational histories for a few weeks at a time which can give you a pretty good idea.

Again, and I respect Shores, show me the receipts including MACR's highlighting specific losses to Ki-43s.