AHC: Shorten the Pacific War?

[tomo pauk]

AFAIK, the U.S. had no a/c-capable radar (akin ASV.II) yet, even one suited for PBYs or B-17s.

Make productive talks with the British.

Absolutely. As noted a number of times upthread, a new design (all-electric, not running on a sine wave, & produced in large numbers) should've been a high priority. And all torpedoes should've been considered: DDs used them, & an air-launched version that actually worked would've made PTs much more effective.

Other platforms can have substitute for torpedoes, submarines can't. Low level bombing done at high speed will also result with ships sinking while improving survivability of the aircraft.
But at an rate, better torps are nice to have on destroyers and aircraft.

That, unfortunately, conflicts with British needs for ASW patrol B-24s.... Unless we can increase production of B-17s or B-24s before the Japanese attack...? Which would probably need an end to the Neutrality Act(s) (& that seems unlikely).

Sorry for not being crystal clear - reinforce Austraia one the war starts.

When it flies, maybe--but I'm a bit dubious the U.S. forces would fly it [the Mosquito].

The F4U was in the pipeline, & I'm not sure the R2800 was ready sooner; AFAIK, there wasn't another "early" design suitable. Merely re-engining a P-36 on F4F with the R2800 seems like a non-starter. Can the P-43/P-44 be accelerated?

USAAF flew the Mosquito in OTL.
In 1941, P&W produced 1460 copies of the R-2800. We also have Wright delivering almost 2000 R-2600s in 1941. Ford also delivered 260 of R-2800 in last 2 months of 1941. Granted, hundreds of engines delivered in December of 1941 do preciously little for pre-Pearl Harbor US forces, but there was still more than 3000 big radials to use.
F4U is a bit too late, my suggestion is that Grumman designs the 'next fighter' around the R-2600 instead of R-1830. Similar for the Seversky/Republic. Once R-2800 is available, switch to that powerplant. Have Vought designing a fighter around 1-stage R-2800 a few months than the historic XF4U, use 2-stage engines once available.
One of suggestions that I didn't post - have Allison designing a 2-stage version of the V-1710 earlier than in OTL.

I'm going to disagree, now, & with the single-engine concept generally; PTO has loooong flying distances, & a twin is a good idea. I'd say, don't allow the cross-country "stunt" flight that led to the wreck of the only prototype P-38. That gets it in service about 2yr sooner--in time for Pearl Harbor. Then, build the daylights out of it, including licence deals with NAA, Convair, Bell (instead of the P-63), & Northrop (instead of the P-61).

Quibble: I'd wait on the Bofors.

My idea with 37mm AA is that by December of 1941 there is at least 40 barrels of it on a CV and BB, 20 barrels on CA and CL, 10 on a DD. Oh, yes, perhaps skipping classic light cruisers and making AA crusisers from day one might be a good idea - 12 x 5in, 30+ barrels worth of 37mm.
P-38 is great, though I'd go with classic twin this time around. Saves on weight, complexity, price and manufacturing time, while offering bigger internal volume in the same time. Second source, preferably at Convair, will come in handy. P-51 - from Inglewood, Dallas and Curtiss St Louis factory.

addition: the OTL P-38 flew before the P-39. In this TL, have Bell produce ALT P-38s instead of P-39s.

 

[tomo pauk]

With regard to the night fighters (not that they mattered too much for the USA, but still): the P-61 will be too late. Use the DB7/A-20 airframe as a base for the NF. The DB7 will be useful with 2-stage or turbo R-1830 or with V-1710, while the heavier A-20 can receive turbo V-1710, better R-2600s or even R-2800s. The A-20 with turbo V-1710 also makes sense as a very fast & rangy bomber.

 

[phx1138]

Make productive talks with the British.

Hmm... That could be part of the Technical Mission deal: Britain gets magnetrons, U.S. gets ASV tech. (Tho the U.S. was getting Canadian-built radars, before RCN, as it was...)

This also offers an opportunity for Britain to avoid bankruptcy & enormous postwar debt...tho that may be a bit of a stretch, in the conditions prevailing.

Aside: if the U.S. does begin a strong buildup on Midway (&, by extension, Wake) as early as '36-7, does Japan even attack?

Other platforms can have substitute for torpedoes, submarines can't. Low level bombing done at high speed will also result with ships sinking while improving survivability of the aircraft.
But at an rate, better torps are nice to have on destroyers and aircraft.

Well... It is possible to sink merchants with guns alone, it's just more hazardous. (As the war progresses, I'd advocate USN fleet boats going from 1x4"/50 to 2, & add a 2d 40mm twin, because large targets worth a torpedo start vanishing.)

Sorry for not being crystal clear - reinforce Austraia one the war starts.

It's only after the U.S. is in it becomes an issue: U.S. demand for B-24s in PTO diverts them from Coastal Command.

USAAF flew the Mosquito in OTL.

I don't think I've ever seen that before. Thx.

In 1941, P&W produced 1460 copies of the R-2800. We also have Wright delivering almost 2000 R-2600s in 1941. Ford also delivered 260 of R-2800 in last 2 months of 1941. Granted, hundreds of engines delivered in December of 1941 do preciously little for pre-Pearl Harbor US forces, but there was still more than 3000 big radials to use.

How many before that? Because any a/c design will have to have that spec in hand, & will need the engine to fly any prototype. Whence the P-38.

F4U is a bit too late, my suggestion is that Grumman designs the 'next fighter' around the R-2600 instead of R-1830. Similar for the Seversky/Republic. Once R-2800 is available, switch to that powerplant. Have Vought designing a fighter around 1-stage R-2800 a few months than the historic XF4U, use 2-stage engines once available.

As noted, you need the actual R2800. Did it exist, or was it just on paper?

Starting with the R2600 is a good idea.

One of suggestions that I didn't post - have Allison designing a 2-stage version of the V-1710 earlier than in OTL.

Agreed. I'd go farther: turbocompound it.

My idea with 37mm AA is that by December of 1941 there is at least 40 barrels of it on a CV and BB, 20 barrels on CA and CL, 10 on a DD. Oh, yes, perhaps skipping classic light cruisers and making AA crusisers from day one might be a good idea - 12 x 5in, 30+ barrels worth of 37mm.

I can live with that.

P-38 is great, though I'd go with classic twin this time around. Saves on weight, complexity, price and manufacturing time, while offering bigger internal volume in the same time. Second source, preferably at Convair, will come in handy. P-51 - from Inglewood, Dallas and Curtiss St Louis factory.

addition: the OTL P-38 flew before the P-39. In this TL, have Bell produce ALT P-38s instead of P-39s.

Do it right, & early enough, you don't need the P-51; I picture RAF buying P-38Ds or -Es. (Export restrictions on the V1710 need to be overcome; if AAF is using turbocompound, versions that are turbosupercharged or 2-speed-supercharged shouldn't be a problem. Or we figure out how to get past the OTL export ban on the turbo'd engines...)

I kind of like the P-39...& with a better V1710 (especially a TC), it wouldn't be a dog. That said, if it's a choice between P-39s & more, & better, P-38s...Bell is a subcontractor.

With regard to the night fighters (not that they mattered too much for the USA, but still): the P-61 will be too late. Use the DB7/A-20 airframe as a base for the NF. The DB7 will be useful with 2-stage or turbo R-1830 or with V-1710, while the heavier A-20 can receive turbo V-1710, better R-2600s or even R-2800s. The A-20 with turbo V-1710 also makes sense as a very fast & rangy bomber.

I like it. I have the sense it might replace some B-26s... OTOH, B-26s with more power (R2800s? V1710TCs? Maybe even V3420s?) could (maybe?) be NFs sooner even then A-20s/DB-7s. Or is that too much a/c for too little performance?

My other option is a 2-place P-38 variant...a bit like the one here. (Scroll to bottom.)

 

[tomo pauk]

...
Aside: if the U.S. does begin a strong buildup on Midway (&, by extension, Wake) as early as '36-7, does Japan even attack?

Premise of this thread is that Japan attacks

It's only after the U.S. is in it becomes an issue: U.S. demand for B-24s in PTO diverts them from Coastal Command.

Needs of the CC can be adressed with few squadrons of the B-24s, and USA is producing plety of Libs.

How many before that? Because any a/c design will have to have that spec in hand, & will need the engine to fly any prototype. Whence the P-38.
As noted, you need the actual R2800. Did it exist, or was it just on paper?
Starting with the R2600 is a good idea.

I've made a mistake - it was 1940 when Wright delivered almost 2000 R-2600s. In 1941 they churned out almost 7200 R-2600s just from Patterson plant! Plus 443 from Cincinati plant.
P&W produced 17 R-2800s in 1940, that will satisfy the needs for several prototypes and/or modifications of an existing A/C. It might be a good idea that Martin produces under license the B-25, so the fighters have 1st call on R-2800s.

Agreed. I'd go farther: turbocompound it.

Do it right, & early enough, you don't need the P-51; I picture RAF buying P-38Ds or -Es. (Export restrictions on the V1710 need to be overcome; if AAF is using turbocompound, versions that are turbosupercharged or 2-speed-supercharged shouldn't be a problem. Or we figure out how to get past the OTL export ban on the turbo'd engines...)

Turbocompound V-1710 on a B-25 or A-20 airframe will provide a significant boost to their range/radius.
RAF will buy P-51s if they have chance, after all they can buy two of those for each P-38, whether ALT or OTL. P-51 has lower logistical footprint than the P-38, a significant factor when a frontline is thousands of miles away from bases. The P-51 done right means 3 factories and 2 engine types (V-1710 and Merlin), 400+- mph with 450 miles radius (not range), with USAAF using it from early 1942 on.
There was no export restrictions on the V-1710 - if a country is allowed to buy, say P-36 from the USA so it can buy V-1710. Including turbo variation. 2-speed S/C on the V-1710 buys preciously little unless it is for bomber, the engine needs a more capcious S/C - thus 2-stage.

Further on the P-51 vs. P-38. P-51 will mean more A/C produced in choosen time frame, pilots are easier to train for 1-engined fighter than on 2-engined, rate of roll can be better, smaller A/C is harder for enemy to spot, less blind spots for a pilot on 1-engined job than on 2-engined.

 

[phx1138]

Premise of this thread is that Japan attacks

Call it keeping an open mind. (Better than calling it early senility.)

Needs of the CC can be adressed with few squadrons of the B-24s, and USA is producing plety of Libs.

Sounds good in theory; OTL, Coastal Command went wanting. Whence the suggestion to increase production. IDK if B-24 production could be accelerated soon enough (or at all, for that).

I've made a mistake - it was 1940 when Wright delivered almost 2000 R-2600s. In 1941 they churned out almost 7200 R-2600s just from Patterson plant! Plus 443 from Cincinati plant.
P&W produced 17 R-2800s in 1940, that will satisfy the needs for several prototypes and/or modifications of an existing A/C. It might be a good idea that Martin produces under license the B-25, so the fighters have 1st call on R-2800s.

That satisfies me. That's enough R2800s for any '40-1 prototypes. If any of those are accepted, production of the R2800 will be increased (& will for the war anyhow).

I have read the R2600 had reliability issues, however...

Turbocompound V-1710 on a B-25 or A-20 airframe will provide a significant boost to their range/radius.

Presuming it's built...but why not?

RAF will buy P-51s if they have chance, after all they can buy two of those for each P-38, whether ALT or OTL. P-51 has lower logistical footprint than the P-38, a significant factor when a frontline is thousands of miles away from bases.

True. OTOH, the Brits & French both bought P-38s, even knowing about the extra logistic drain; TTL, even disallowing V1710TCs, the P-38 would be better than what they got OTL, available in greater numbers (& right away), & with range to reach deep into Europe (Germany soon enough), & that's at least 6mo before the Brits even talk to NAA. (The OTL P-38 order was March '40; TTL, it could be as early as October or November '39, while the OTL deal with NAA was April '40 & first flight in October, deliveries starting one year later.)

The P-51 done right means 3 factories and 2 engine types (V-1710 and Merlin), 400+- mph with 450 miles radius (not range), with USAAF using it from early 1942 on.

Enough P-38s, with proven performance, means an effective long-range escort is in service when 8th AF first reaches Britain... (Whether the P-38s are actually used for escort is another matter, & beyond the scope of this thread.)

There was no export restrictions on the V-1710

Yeah, reading the WP page, it says that was an RAF request. A damn peculiar one, IMO, but...

Further on the P-51 vs. P-38. P-51 will mean more A/C produced in choosen time frame, pilots are easier to train for 1-engined fighter than on 2-engined, rate of roll can be better, smaller A/C is harder for enemy to spot, less blind spots for a pilot on 1-engined job than on 2-engined.

All true. However, in PTO, speed, climb, & survivability are (arguably) more important. Roll rate is irrelevant, really; if you're in a turning fight with an A6M, you're stupid or dead, & probably both. Boom & zoom.

Come to think of it, this might mean quite a few surplus P-40s end up in ROC, DEI, or Finn AF hands. The Flying Tigers might be really successful. And the Finns might give the Red Air Force some nasty shocks.

 

[tomo pauk]

...
I have read the R2600 had reliability issues, however...

Looks like the problems were with engines manufactured in Cincinatti plant - linky.

True. OTOH, the Brits & French both bought P-38s, even knowing about the extra logistic drain; TTL, even disallowing V1710TCs, the P-38 would be better than what they got OTL, available in greater numbers (& right away), & with range to reach deep into Europe (Germany soon enough), & that's at least 6mo before the Brits even talk to NAA. (The OTL P-38 order was March '40; TTL, it could be as early as October or November '39, while the OTL deal with NAA was April '40 & first flight in October, deliveries starting one year later.)

Enough P-38s, with proven performance, means an effective long-range escort is in service when 8th AF first reaches Britain... (Whether the P-38s are actually used for escort is another matter, & beyond the scope of this thread.)

I'm afraid that you put too much faith into P-38 programme for early war, even with OTL improvement of the timetable. Allison delivered about 60 V-1710s in the 1st half of 1940, a drop in the bucket for what is needed. Granted, by late 1940 things improved, monthly production went into couple of hundreds, but that is too late for Fance of for the BoB.
France and UK were signing contracts for anything the USA was producing, or was about to produce, since they have had a major war on. Logistic drain for France or Britain for European war is a pale shade what the USA will expect with a war thousands miles away.
Now that we're talking about engines, the sooner USAAC forgets about 'hi-per' engines the better. Shift any extra funding they have to the R-2800, R-2600 (keeping an eye on the Cincinnati and other plants), V-1710 and Merlin.

Yeah, reading the WP page, it says that was an RAF request. A damn peculiar one, IMO, but...

Request was realistic. When the 1st contract for the Lightning I was signed, there was no P-38 of any sort flying.

All true. However, in PTO, speed, climb, & survivability are (arguably) more important. Roll rate is irrelevant, really; if you're in a turning fight with an A6M, you're stupid or dead, & probably both. Boom & zoom.

Rate of roll is important, we know that people at eg. Supermarine, Lockheed, Bell etc. were trying to improve their products on that field. Problem the Zero had was it's slow rate of roll as speed went up, while the Fw 190 was praised both by LW and Allied pilots for it's rate of roll, and P-40 was regarded well in that field. Speed was no problem with P-51; P-51 with Merlin or 2-stage V-1710 will be a good climber, and 50 mph faster than Zero. It will get quite a tweaking for the P-38 to improve dive speed, no problem for P51 even as-is.
Less blind spots and smaller size contribute to survivability.

 

[naraic]

The best way to shorten the Pacific War in my opinion would be if the Royal Navy has a decent Pacific Fleet in late 1941. If this fleet contains a number of submarines operating from Singapore the Japanese Supply line will be quickly crippled facing both American and British threats.

What's the best way to have a Royal Navy fleet East of the Suez? In my opinion it's to double down on the Taranto raid perhaps by saving one of the unlucky fleet carriers (Courageous, Glorious and Ark Royal). Cripple the Italian fleet in the Mediterranean even more than historically. Free up a number of battleships and carriers for operations East of the Suez. Butterflies flap in Crete meaning a larger Royal Navy presence a better air shield and less damage.

A Fleet in Singapore can operate when needed and withdraw if the full Japanese Fleet is present. Japan can't do Pearl Harbour, Philipines and Thailand/Malaya/Burma simultaneously if there is a real fleet in Singapore. At least they can't don't without being wiped out on one front. If they move a carrier division to Malaya Pearl will be much better off (even if only by atritting the Japanese airgroups) as the Japanese won't be able to suppress all air fields. If the Japanese move the light fleets from Philipines they are taking a big risk there. If they don't do something any invasion convoy for Thailand/Malaya will be ripped apart.

A doable fleet in Singapore if WW2 went better for Britain is 3 carriers (One old small carrier a Hermes or an Eagle or Argus, two larger carriers anything from a folly, an Ark or some armoured fleets) 3 fast capital ships (POW Renown & Repulse). 3 slow capital ships (QE or NelRod).

If Taranto is double down on the Italians may be unable to escort convoys meaning greater submarine success meaning that Africa goes better for the allies and is wrapped up (or the area of operations limited so that less submarines are needed) before the end of 1941 allowing the long range subs designed for the Pacific to be released for service East of the Suez.

Sorry for the completely different turn on the thread I just noticed that there was no discussion on a better British performance.

 

[tomo pauk]

A better British performance in SE Asia might include the proper C&C of their air assets, both ground- and CV-based, later ones provided we have at least couple of carriers there in late 1941. By what time British commaders might also apprecite that major fleet operation needs air cover, and Malayan airfields can provide that. Better/more radars are necessary, and indeed more/better subs are great asset, both for sinking some ships and scouting. I'd try to deploy the P-40s there due to their better range than Hurricanes, plus they completely own any japanese aircraft bar Zero; Oscar included.
A commander that will not panic when 1st Japanese units land is needed.

 

[Insider]

All it takes, is to make Arthur Percival a mildly incompetent commander, who would order his troops to dig in and fight for the last man and last round. Failing that replace him with somebody else. My pick is Percy Hobart who was kicked out by Wavell. Actually Wavell himself would be just as excellent, but he was busy elsewhere.

 

[CV12Hornet]

Some discussion on another site suggests there's another possibility for shortening the war: the US going all-in in New Guinea instead of continuing up the Solomons and starting the Central Pacific campaign. The guy I was talking to stated that by shuffling all the men, ships, and aircraft there the US would be invading Luzon before 1943 is over, with the lack of fleet train I mentioned before mitigated by the proximity of Australia to base the oilers out of.

 

[tomo pauk]

Some discussion on another site suggests there's another possibility for shortening the war: the US going all-in in New Guinea instead of continuing up the Solomons and starting the Central Pacific campaign. The guy I was talking to stated that by shuffling all the men, ships, and aircraft there the US would be invading Luzon before 1943 is over, with the lack of fleet train I mentioned before mitigated by the proximity of Australia to base the oilers out of.

(my bold)
There is no enough of oil wells, refineries, ammo and weapon factories in Australia to cater for Australian needs, let alone for US needs.

 

[Glenn239]

Some discussion on another site suggests there's another possibility for shortening the war: the US going all-in in New Guinea instead of continuing up the Solomons and starting the Central Pacific campaign. The guy I was talking to stated that by shuffling all the men, ships, and aircraft there the US would be invading Luzon before 1943 is over, with the lack of fleet train I mentioned before mitigated by the proximity of Australia to base the oilers out of.

Get the Soviets to somehow attack in June or July 1944 instead of 1945, then have the US offer better terms than unconditional surrender after the Marianas fall. Have Spruance chase down and annihilate the IJN during the battle instead of letting it go. Between those triple shocks, maybe....

 

[Insider]

June 1944? That presents another scenario...
Valkyries fly high in Germany, and generals throw a towel. Soviets are furious as they would not get all of Central Europe, they shift their forces and steam roll into China by the end of August 1944.

 

[tomo pauk]

...
Have Spruance chase down and annihilate the IJN during the battle instead of letting it go.
..

During what battle?

 

[CV12Hornet]

(my bold)
There is no enough of oil wells, refineries, ammo and weapon factories in Australia to cater for Australian needs, let alone for US needs.

It wouldn't be produced in Australia, it'd be transported there by civilian shipping (which the US was cranking out way faster than specialized military oilers) and then pushed by military transports to the front lines.

 

[tomo pauk]

It wouldn't be produced in Australia, it'd be transported there by civilian shipping (which the US was cranking out way faster than specialized military oilers) and then pushed by military transports to the front lines.

IMO, the Central Pacific campaign offers much shorter way to bring in reinforcemets (saves on time and shipping, there is no loading from one ship to another ship), avoids any sizable ground campaign that draws from US Army units, while destroying Japanese Navy in process. With better and more of radars, aircraft, ship-borne AA, workable torpedoes and low-level bombing the Japanese Navy is destoyed much faster than in OTL. New Guinea campaign leves a thorn in the Allied side with the Solomons in Japanese hands, while carriers in relatively confined waters around the NG are not in healthy surrounding.

 

[phx1138]

Looks like the problems were with engines manufactured in Cincinatti plant

Thx for the link, that makes interesting reading...

I'm afraid that you put too much faith into P-38 programme for early war, even with OTL improvement of the timetable. Allison delivered about 60 V-1710s in the 1st half of 1940, a drop in the bucket for what is needed. Granted, by late 1940 things improved, monthly production went into couple of hundreds, but that is too late for Fance of for the BoB.

Which forgets the demand from the P-38 program: V1710s will have to be available in greater numbers.

That said, I looked at the first flight date on the P-38, P-39, & P-40 again. I've been getting my years wrong, somehow: P-39 first flew 6 April 1938, P-40 14 October 1938, P-38 27 January 1939 (& not introduced to AAF until July '41, so the claim for "2yr less" that I've seen has to be wrong... A service intro only 6mo after first flight seems extremely improbable.)

That said, the V1710 was being used by both P-39 & P-40, too, so production would have to increase in any event.

France and UK were signing contracts for anything the USA was producing, or was about to produce, since they have had a major war on. Logistic drain for France or Britain for European war is a pale shade what the USA will expect with a war thousands miles away.

Agreed.

Now that we're talking about engines, the sooner USAAC forgets about 'hi-per' engines the better. Shift any extra funding they have to the R-2800, R-2600 (keeping an eye on the Cincinnati and other plants), V-1710 and Merlin.

Also agreed. If there are issues with production of the V1710, I wonder if the *P-40 might be specified with the R2600, instead? (If so, could be Curtiss loses the competition to Seversky... Or maybe the *YP-42 has the R2600, & gets adopted?)

Request was realistic. When the 1st contract for the Lightning I was signed, there was no P-38 of any sort flying.

This page says the contract was in 3/40, which postdates the XP-38's maiden flight by over a year...

Rate of roll is important, we know that people at eg. Supermarine, Lockheed, Bell etc. were trying to improve their products on that field. Problem the Zero had was it's slow rate of roll as speed went up, while the Fw 190 was praised both by LW and Allied pilots for it's rate of roll, and P-40 was regarded well in that field. Speed was no problem with P-51; P-51 with Merlin or 2-stage V-1710 will be a good climber, and 50 mph faster than Zero. It will get quite a tweaking for the P-38 to improve dive speed, no problem for P51 even as-is.

P-38s will out-accelerate & outclimb P-51s every time, & can outrun A6Ms without half trying. The dive compressibility issues are serious; TTL, there's much less chance of the fix kits being lost when the C-54 carrying them is shot down...

Less blind spots and smaller size contribute to survivability.

Fair point. Against A6Ms, IMO, not a big problem.

Sorry for the completely different turn on the thread I just noticed that there was no discussion on a better British performance.

Don't apologize. The broader the view, the better. So what have the Sovs got? And how can Hitler completely bugger things up? ('cause you just know he will.)

The best way to shorten the Pacific War in my opinion would be if the Royal Navy has a decent Pacific Fleet in late 1941. If this fleet contains a number of submarines operating from Singapore the Japanese Supply line will be quickly crippled facing both American and British threats.

What's the best way to have a Royal Navy fleet East of the Suez? In my opinion it's to double down on the Taranto raid perhaps by saving one of the unlucky fleet carriers (Courageous, Glorious and Ark Royal). Cripple the Italian fleet in the Mediterranean even more than historically. Free up a number of battleships and carriers for operations East of the Suez. Butterflies flap in Crete meaning a larger Royal Navy presence a better air shield and less damage.

This is all excellent thinking, IMO. However...

Japan can't do Pearl Harbour, Philipines and Thailand/Malaya/Burma simultaneously if there is a real fleet in Singapore.

We've been presuming Japan goes ahead on OTL's schedule, so...you'll have to figure out how to add subs & such to Oz after it all starts.

If you can have a British Pacific Fleet in Oz (feel free to nominate a CO: V/A Stuart Bonham-Carter?), & he's willing to work under Gieger as ComSWPA (thereby freeing Doyle's subs to move to Hawaii under English...)...

In that vein, what about the Dutch? They had a few subs in DEI, didn't they? What happens to them?

If Taranto is double down on the Italians may be unable to escort convoys meaning greater submarine success meaning that Africa goes better for the allies and is wrapped up ...before the end of 1941

Speculation on that is a bit far afield from the aim, here... (I'll say, if it happened, it would also free U-boats for ops off North America.)

However...

allowing the long range subs designed for the Pacific to be released for service East of the Suez.

That could not be good for Japan.

Some discussion on another site suggests there's another possibility for shortening the war: the US going all-in in New Guinea instead of continuing up the Solomons and starting the Central Pacific campaign. The guy I was talking to stated that by shuffling all the men, ships, and aircraft there the US would be invading Luzon before 1943 is over, with the lack of fleet train I mentioned before mitigated by the proximity of Australia to base the oilers out of.

That is the most unusual approach I think I've heard.

My problem with it is, it looks like a real slog, under IJAAF air the whole way. Central Pacific offers long jumps, putting Allied (U.S....) forces much nearer Japan much sooner.

Yes, going through/out of New Guinea means starting sooner... The advantages might outweigh.

OTOH, I'd far sooner bypass the P.I. entirely & go directly from Saipan to Okinawa, masking off the P.I. with CVs, & shortening the war.

IMO, the Central Pacific campaign offers much shorter way to bring in reinforcemets (saves on time and shipping, there is no loading from one ship to another ship), avoids any sizable ground campaign that draws from US Army units, while destroying Japanese Navy in process. With better and more of radars, aircraft, ship-borne AA, workable torpedoes and low-level bombing the Japanese Navy is destoyed much faster than in OTL. New Guinea campaign leves a thorn in the Allied side with the Solomons in Japanese hands, while carriers in relatively confined waters around the NG are not in healthy surrounding.

That, too.

Get the Soviets to somehow attack in June or July 1944 instead of 1945

With Japan at peace & Germany the obviously bigger threat, I don't feature Stalin seeing the need (or gain).

then have the US offer better terms than unconditional surrender after the Marianas fall

That seems very possible, except for Congress... Beyond that, tho, the terms Japan insisted on (keeping an Emperor) were the ones they got OTL: you need to have PotUS (FDR?) when the surrender discussions come around to expressly agree to give it to them (which the Atlantic Charter says Japan will get, once defeated), & which Truman OTL wouldn't. Doing it immediately with the fall of Saipan (& the resulting change of gov't in Tokyo) might encourage the "Japanese Valkyrie" to act.

Have Spruance chase down and annihilate the IJN during the battle instead of letting it go.

Maybe. AIUI, the situation was such he couldn't risk it, & if he'd pursued, he'd have left the landings exposed: he'd have given Ozawa (?) what Kurita couldn't (wouldn't) achieve off Luzon...

Between those triple shocks, maybe....

Maybe.

One other thing: bypass Pelelieu!

One scary thing to remember: if this scenario ends without the Bomb being used on Japan, it's very, very possible it ends up being used in Europe in the '50s.

 

[Glenn239]

During what battle?

Marianas, June 1944.

 

[Glenn239]

With Japan at peace & Germany the obviously bigger threat, I don't feature Stalin seeing the need (or gain).

The USSR attacking Japan was the end of the Pacific War. So, to have the end happen sooner, you need the USSR to attack sooner. QED!

 

[tomo pauk]

Also agreed. If there are issues with production of the V1710, I wonder if the *P-40 might be specified with the R2600, instead? (If so, could be Curtiss loses the competition to Seversky... Or maybe the *YP-42 has the R2600, & gets adopted?)

I've suggested that Army in mid/late 1930s abandons hi-per engines that they shoved through the neck of Continental and Lycoming, and use the funds to accelerate R-2600, R-2800, V-1710. Plus Merlin already from 1939.
With less complicated twin engined fighter (= have them more and earlier), a R-2800-based and R-2600-based fighter, the P-40 is needed less. Plus the P-51 should be adopted by Army by 1941.

This page says the contract was in 3/40, which postdates the XP-38's maiden flight by over a year...

Between February 12th 1939 and September 1940 there is exactly zero P-38s of any kind (XP-, YP- etc) that can take off and fly.

P-38s will out-accelerate & outclimb P-51s every time, & can outrun A6Ms without half trying. The dive compressibility issues are serious; TTL, there's much less chance of the fix kits being lost when the C-54 carrying them is shot down...

Perhaps we didn't understand each other on P-38 and P-51. My suggestion was that ALT twin engined fighter is produced, in two factories. However, I still stand by suggestion that P-51 is to be produced by 3 factories by winter of 1941/42. Make it four factories if NAA actually wins over the Navy.

Marianas, June 1944.

Thank you.
ITTL, the equivalent of the Marianas turkey shooting will probably happen in 1942.