Why didn't the army develop the P-51?

[oldcrowcv63]

Interesting discussion on which guns to throw overboard.

One scenario that I didn't consider because I wasn't sure how long it would take is to simply transition the pilots of the 49th group to a new aircraft. Ship the Mustang Is to Oz in January and February and begin the transition around the end of February or early March. How long did it typically take existing squadron's pilots to transition to a new type? I've tried to find that in some in-hand sources but can't really get a good feel. The FEAF 3rd Pursuit squadron on Luzon received flyable P-40Bs in early July 1941 and started their transition from P-35As at that time. I believe the senior pilots were essentially combat capable by early September. So a bit over two months to transition? I can't quite figure out how long it took the 9th FS of the 49th group to transition to P-38s but it seems pretty fast as they were evidently flying combat missions January 19, '43 from Dobodura, New Guinea after being engaged with P-40Ks at 4 Mile airstrip in late November, 42. Of course non-engine related logistical and maintenance support would probably be a pacing issue as much or more than pilot training. Don't know the answer here, just asking.

 

[drgondog]

Oldcrow - two months seems to be in the strike zone of US fighter pilot unit transition in early stages of war.

The 78th FG took a little less to convert from P-38 to P-47 in March, 1943 to April 1943.

The other extremes? 4th FG converting from P-47 to P-51 in 1 to 5 days with several 'familiarity' runs on the way to the target for the transition from P-47 to P-51. The 355th took a week for the same conversion, 352nd - three weeks only because they didn't have enough 51s to go around for check rides. Wartime a little different than pre-Pearl harbor for US.

 

[oldcrowcv63]

Thanks, drgondog

Oldcrow - two months seems to be in the strike zone of US fighter pilot unit transition in early stages of war.

The 78th FG took a little less to convert from P-38 to P-47 in March, 1943 to April 1943.

The other extremes? 4th FG converting from P-47 to P-51 in 1 to 5 days with several 'familiarity' runs on the way to the target for the transition from P-47 to P-51. The 355th took a week for the same conversion, 352nd - three weeks only because they didn't have enough 51s to go around for check rides.

1 to 5 days! HS!

Wartime a little different than pre-Pearl harbor for US.

that makes sense

 

[Shortround6]

Some of it depends on if it is the first squadron or group to convert to a new type or if a number of groups have converted already. For later groups both pilot manuals and maintenance manuals are available. In many cases a few ground crewmen if not a few pilots were would be transferred or loaned while the conversion took place. It can also depend on the experience of the squadron/group in question and what they are converting from/too.
The 4th fighter group had started combat flying Spitfires, almost 1 1/2 years before they got the P-51s. They got their first P-47s in March of 1943 and the Mustangs in Feb 1944. Maybe they had few, if any, Spitfire pilots and ground crew left, I don't know. Converting to the P-47 might be harder than converting from it. The P-47 having higher take-off and landing speeds and having a turbo to manage. I don't know if their are any other handling problems particular to the P-47 vs the P-51.

The First P-51B arrived in England in Sept 1943, In Oct they were arriving "steadily", The 354th group got it's first plane Nov 11th. Dec 1 they do a fighter sweep over Belgium and France, Dec 5th sees them escorting B-17s as far as Paix, France with P-47s taking over from there. Dec 16th sees the first long range mission to Kiel.

Lt. Col. Don Blakeslee is in command of the 4th fighter group when it makes it's transition in Feb 1944 but he had been sent for training on the P-51 back in Nov 1943 and had been detached to the 354th fighter group to lead them on it's first missions.

 

[drgondog]

The crew chiefs on the Spit were re-trained on P-47, then the P-51 for the 4th FG.

The 4th got its first Mustangs on February 25th, then 'borrowed' the P-51s sent to 355th at same time to be able to fly all of them on the first Berlin Mission on March 4 and 6. The 355th flew one squadron (357) on March 8, got all the loaners back from 4th FG on March 8, then flew all P-51 on March 9.

So, the 4th had at least 70% of their Crew Chiefs knowledgeable in the Merlin whereas the 355th crews had zero experience.

 

[oldcrowcv63]

I'd imagine, in the worst case, there would have been whatever corporate pubs that had been created along with the initial production batch of aircraft and a cadre of NAA technicians following their aircraft where ever they went to help ease transition problems by whomever turned out to be the end users. Even in the case of FEAF in the PI, one of the early batches of evacuees from Bataan were the Curtiss technical assistance folks who I believe were taken out on submarines.

I can only imagine what the veterans of the PI debacle who comprised some of the 49th FG leading pilots, and who had made the best use of the P-40B E they could, would have felt at the prospect of climbing into Mustang I, let alone flying it into combat.

It didn't happen and the obstacles to it actually happening were effectively insurmountable in the time frame, but it's seductive to ponder what might have been.

 

[GregP]

I'd think the British Merlins would be Whitworth while the Packard Merlins were SAE, so they'd need an entire set of new tools, too.

Might be wrong there, but I've turned a few wrenches on both.

 

[wuzak]

I'd think the British Merlins would be Whitworth while the Packard Merlins were SAE, so they'd need an entire set of new tools, too.

Might be wrong there, but I've turned a few wrenches on both.

I believe that Packard Merlins were built with all British fasteners.

US bound Merlins had SAE prop shafts, British had SBAC prop shafts. The 2 stage Packard Merlins (some, most, all?) also had the Wright designed supercharger gearbox.

 

[Shortround6]

I believe the basic engines were supposed to be pretty much interchangeable. As Wuzak says the prop shafts differed and the supercharger drive differed. other accessories may very well have differed, vacuum pumps, hydraulic pumps, generators, even starters. US Merlins used Bendix carburetors. So it is quite possible to work on British and American Merlins and see different fasteners/fittings on the outside bits and pieces. Inside pieces were supposed to be the same, connecting rod bolts, cylinder tie down bolts and things like that. There is a story that the British supplied up to 600 Merlin engines as spares or spare parts for American P-40F/L aircraft in North Africa.

 

[Balljoint]

Historically, this seems to be the most commonly presented theme. However I think the real evidence of that prioritization comes a bit later like late 1942 starting with Torch. My understanding is that from December 1941 thru October 1942 (a bit longer than the time period with which I am most concerned and addressing), US troops and sailors were primarily engaged (fighting and dying in the greatest numbers) in the PTO. Moreover, PTO was the theater where the nation had the war forced upon its citizens. So there was an emotional dimension to a political reality. Strategically, the prioritization was European victory first. Politically, there is a fair amount of evidence that both the military and civil leadership were pandering to the public and acting in ways to present the PTO as the primary theater. Its a tangled period, but I think you are responding in the stratosphere (looking at the big picture) and I am down in the weeds. (looking at very local and very time specific events).

At the risk of going a bit afield, my take (I'm old enough to remember though not understand Pearl Harbor and the public angst) is that at the time the US was little different from the USSR in the willingness to accept top-down decisions. Roosevelt was in complete control of the war. The Pacific was a blue water war and the US had just lost its naval might. So the US Navy was tasked with holding the line as best it could with its surviving and underappreciated carriers. Thus through 20-20 hindsight, I see the strategy for Darwin as withdrawing targets, some interceptor defense and taking out the Japanese bases with naval action plus New Guinea.

My big picture approach is pretty much informed and often modified by your detailed digging.

Pretty much historically true, although I believe the reality of the invasion threat is debated by historians. I think there was some IJA consideration given to occupying the northern reaches of Oz, but ultimately dismissed as beyond the capability of the army to support and not a part of their original Phase 1 plan. I'd defer here to someone who has spent a lot more time reading and thinking about the Australia invasion threat. They inhabit the forum and, if we are lucky, one may weigh in.

However, it was the P-40Es of the FEAF defending the PI and those of 17th PPS in Java and the 49th Fighter Group's three squadrons that were dedicated to the defense of Darwin during the IJ raids from early December 1941 through September, 1942 that are the focus of my interest. During that period, the USAAF P-40Es fought their own isolated war against the raiding IJ aerial forces. From about February 1942 on, the USN was essentially guarding the Australian Eastern flank during the Spring and then later caught up in the Watchtower offensive.

I think the threat of invasion was very real for Australia, a possibility for the JIN and a nonstarter for the JIA.

The Darwin raids come in two flavors; the land-based bombers and accompanying Zeros and variants thereof, and the big raid of February 19, 1942. The former were more nuisance actions in the big picture that called for at least some interception though Darwin was not that much of a target after the February 19 raid. The later was an overwhelming attack by the JIN 1st Carrier Air Fleet comprising the four carriers later in action at Midway supplemented by land-based high-altitude bomber. This group was the best in the world during its "running-wild-in-the-Pacific" period and more interceptors would have meant more allied loses –though a handful of P-40s caught flatfooted manager to take down a raider or two. After the devastating February 19th action Darwin was more heavily fortified and the harbor was no longer used for inviting targets.

 

[oldcrowcv63]

At the risk of going a bit afield, my take (I'm old enough to remember though not understand Pearl Harbor and the public angst) is that at the time the US was little different from the USSR in the willingness to accept top-down decisions. Roosevelt was in complete control of the war. The Pacific was a blue water war and the US had just lost its naval might. So the US Navy was tasked with holding the line as best it could with its surviving and underappreciated carriers. Thus through 20-20 hindsight, I see the strategy for Darwin as withdrawing targets, some interceptor defense and taking out the Japanese bases with naval action plus New Guinea.

I think the last sentence is probably pretty much true, but I'd probably stop short of saying Roosey was in "complete" control cause there were a host of elements out of any one person's control. Also, while the US public was probably more accepting of authority than it is today, it's always been kind of a cantankerously rebellious lot from my reading of history. I've read that there was a strong communist sympathetic movement demanding that US leadership open a 2nd front long before it was feasible, in order to relieve NAZI pressure on the Russians. Whatever the issue, the military and political leadership did have to be careful to protect their political lines of support which, in the democracy fighting with a conscript army, was probably as vital as its logistics.

I think the loss of the PH battleships was quickly recognized (especially by Nimitz) as anything but a fatal blow. The prewar drive across the pacific with the USN's fuel guzzling battle fleet was probably not practical considering the thinness of USN ability to move fuel oil. It was barely able to operate the carriers. Would the introduction of Mustang I's to replace the P-40Es had much of an impact beyond protecting Darwin and later Port Moresby, probably not... The pilots of the 49th FG found ways to make up for some of the deficiencies of their equipment and did a bit better than their FEAF predecessors.

My big picture approach is pretty much informed and often modified by your detailed digging.

I hope you are using 'you' in a generic sense cause just one, sometime dubious source may fall short of the mark. especially this one 'you'.

I think the threat of invasion was very real for Australia, a possibility for the JIN and a nonstarter for the JIA.

I'll rather let someone from Australia comment on this which I believe has been discussed in greater detail in other threads. I miss renrich.

The Darwin raids come in two flavors; the land-based bombers and accompanying Zeros and variants thereof, and the big raid of February 19, 1942. The former were more nuisance actions in the big picture that called for at least some interception though Darwin was not that much of a target after the February 19 raid. The later was an overwhelming attack by the JIN 1st Carrier Air Fleet comprising the four carriers later in action at Midway supplemented by land-based high-altitude bomber. This group was the best in the world during its "running-wild-in-the-Pacific" period and more interceptors would have meant more allied loses –though a handful of P-40s caught flatfooted manager to take down a raider or two. After the devastating February 19th action Darwin was more heavily fortified and the harbor was no longer used for inviting targets.

And after Midway, things changed pretty quickly down under.

 

[Shortround6]

A Problem with early deployment of a lot of things was the fear of invasion of the west coast, at least for a few weeks or months after Pearl Harbor. The 41st Infantry Div was deployed to a number of spots in Oregon and Washington states to guard against a possible invasion in Dec of 1941. They were gathered back up and prepared for over seas deployment by March but the 3rd Div took over their posts, they were not abandoned. Granted ALL these divisions needed more training and there was a shortage of shipping immediately available but a good part of the 41st was sent from the west coast to the East Coast (New York) to board ship.

 

[nuuumannn]

Whilst I don't have too much detail to hand, but I remember reading about Australia's preparation for invasion by Japan; the threat was certainly regarded as very real in both Aussie and New Zealand, although that doesn't state that the Japanese were definitely going to go ahead with such a thing, but in both countries preparations were taken very seriously. In Australia there was the Brisbane Line, which was essentially a horizontal line drawn from Brisbane across the continent and everything north of it was to be abandoned, leaving any invading army to its fate, although there is some controversy regarding whether this was actually policy or not:

"The Brisbane Line" - Was it fact or was it a myth?

https://en.wikipedia.org/wiki/Brisbane_Line

With the sheer physical size of Australia and the vast empty spaces, any army invading from the north would run out of steam pretty quickly if not kept with a constant supply stream by sea and over land; Aussie is a BIG country.

 

[oldcrowcv63]

A Problem with early deployment of a lot of things was the fear of invasion of the west coast, at least for a few weeks or months after Pearl Harbor. The 41st Infantry Div was deployed to a number of spots in Oregon and Washington states to guard against a possible invasion in Dec of 1941. They were gathered back up and prepared for over seas deployment by March but the 3rd Div took over their posts, they were not abandoned. Granted ALL these divisions needed more training and there was a shortage of shipping immediately available but a good part of the 41st was sent from the west coast to the East Coast (New York) to board ship.

Your post reminded me of the brief history of the Vultee P-66 Vanguard in USAAF service and I wondered how its history compared to the scenario addressed in the current thread. As I understand it from Wikipedia, the aircraft was ordered by Sweden but embargoed and taken over by the USAAF after PH and deployed to airfields to bolster West Coast defenses for the anticipated imminent Japanese invasion. Of course Sweden wasn't at war and there weren't the familial ties that may have had some bearing on the decisions made regarding the Mustang I but this seems like it might be a counter example of the situation we've been discussing.

 

[VBF-13]

the sheer physical size of Australia and the vast empty spaces, any army invading from the north would run out of steam pretty quickly if not kept with a constant supply stream by sea and over land; Aussie is a BIG country.

There's no way the Japs could have ignored the Aussies and expected to continue on in that area. That big island was just too strategic.

 

[Shortround6]

Your post reminded me of the brief history of the Vultee P-66 Vanguard in USAAF service and I wondered how its history compared to the scenario addressed in the current thread. As I understand it from Wikipedia, the aircraft was ordered by Sweden but embargoed and taken over by the USAAF after PH and deployed to airfields to bolster West Coast defenses for the anticipated imminent Japanese invasion. Of course Sweden wasn't at war and there weren't the familial ties that may have had some bearing on the decisions made regarding the Mustang I but this seems like it might be a counter example of the situation we've been discussing.

The timing is wrong, the US Embargoed the aircraft in the fall of 1940, claiming that they were afraid that they would fall into German hands (ships would have to pass between Norway and Denmark, both German occupied to get to Sweden). The British agreed to take 100 of the 144 plane batch lend-lease to use as trainers in Canada having already rejected the Vulture design as an operational aircraft. In the Spring of 1941 the Chinese were desperate for anything that would fly and the British released the planes back to the US for shipment to China. Some reached China but 50-60 were impressed by the US after Pearl Harbor but that was over a year after the Swedish "embargo".