July 1st 1937: your own USAAC/USAAF/USAF?

[Shortround6]

No need for miracles
The XF4U flew for the 1st time on 29th May 1940 - maybe Army just then became aware that (X)R-2800 really deserves attention? Navy was sure about the R-2800 already in June 1938, when they signed a contract covering the future F4U. Even in case the Army decides in mid 1939 to give a try with a fighter based around the R-2800, that gives an extra year. The Army have had enough 'faith' to order the R-2800-powered bomber, from the drawing board, in Sept/Oct 1939 (quote from Joe Baugher's site):

Except that the F4U was extensively redesigned from XF4U to the F4U-1 and such was the 'pace' that both Goodyear and Brewster were brought into the production program over 6 months before the first production F4U-1 flew and mock-ups of the night fighter F4U-2 were being inspected 6 months before the F4U-1 flew. 2nd production F4U-1 was accepted by the Navy by July 31 1942. At that time 81 P-47s had been built. People now want to divert Chance Vaughts engineering efforts from getting the F4U into production and service with the Navy and have them design alternative wings if not fuselage for an "Army" version. Just leaving the hook and catapult points off and bolting the folding wings in place doesn't change performance much ( unless one can find a performance report for the hundreds if not over 1000 Goodyear aircraft that were made that way).
We have been over the grab the B-26 engines and shove them in a fighter thing before. You wind up spending millions of dollars on a fighter that will be second rate by the beginning of 1943. And do you delay the P-47? The Turbo system is too big to back fit into a fighter designed without it and a fighter designed to fit the turbo system but not fitted with it is an over sized/over weight turkey.
The early R-2800s offer 1500hp at 14,000ft from a 2270lb engine. Which doesn't offer anything much over a Merlin XX (Packard V-1650-1).

I'm not aware that anybody actually tried that in the USA, hence no discoveries of the reasons for not using any? As for 'why' - as an insurance if the future turbo-equipped aircraft develop issues that might hamper timely introduction in service, while offering the performance punch similar to those? Should be quite simpler to produce and maintain, and cheaper than future P-38 with pair of turbos per aircraft.

There were a few commercial aircraft with push-pull nacelles in the early 30s. The Airacuda's used pushers with extension shafts. one of the drawings for an initial P-38 design was a push pull and another used buried engines in the fuselage with extension shafts/gear boxes in the wings and pusher props. how much actual engineer work was done on these I don't know.

the use of "push-pull" does nothing for the altitude rating of the engines involved. So a push-pull offers little altitude performance over a conventional twin using the "same" engines.

 

[tomo pauk]

Except that the F4U was extensively redesigned from XF4U to the F4U-1 and such was the 'pace' that both Goodyear and Brewster were brought into the production program over 6 months before the first production F4U-1 flew and mock-ups of the night fighter F4U-2 were being inspected 6 months before the F4U-1 flew. 2nd production F4U-1 was accepted by the Navy by July 31 1942. At that time 81 P-47s had been built. People now want to divert Chance Vaughts engineering efforts from getting the F4U into production and service with the Navy and have them design alternative wings if not fuselage for an "Army" version. Just leaving the hook and catapult points off and bolting the folding wings in place doesn't change performance much ( unless one can find a performance report for the hundreds if not over 1000 Goodyear aircraft that were made that way).

Maybe you've misunderstood me. I did not said that (X)F4U was able to solve all USAF's worries. I was trying to underline that USAF was some two years behind USN in appreciation of R-2800's potential.
What ever the P-47B was built, it was not up the scratch, because of structural issues and fabric covered ailerons, among other stuff. If the P-47'B' is produced 1st in early 1941, instead of late 1941, that means the Republic can include modifications in order to have a battle worthy P-47'C' in early 1942, instead in autumn of 1942.

We have been over the grab the B-26 engines and shove them in a fighter thing before. You wind up spending millions of dollars on a fighter that will be second rate by the beginning of 1943. And do you delay the P-47? The Turbo system is too big to back fit into a fighter designed without it and a fighter designed to fit the turbo system but not fitted with it is an over sized/over weight turkey.
The early R-2800s offer 1500hp at 14,000ft from a 2270lb engine. Which doesn't offer anything much over a Merlin XX (Packard V-1650-1).

I've never said, in this thread, 'let's build a fighter around a single stage R-2800, that one solves our problems'. I've said: 'is it too early to contemplate about a fighter with turbo R-2800?', to what you replied 'The Turbo R-2800 (P-47) was probably about as quick as could be expected. everybody seems to want miracles.<sinp>'.

the use of "push-pull" does nothing for the altitude rating of the engines involved. So a push-pull offers little altitude performance over a conventional twin using the "same" engines.

The push pull offers performance advantage over all altitudes vs. a conventional twin, due to decreased drag. It will also roll better than a 'classic', because there is no hefty engines on the wings. Pilot has a field of view that is unobstructed by engine nacelles, let alone the booms (vs. P-38 ).
The main shortcoming of early successful US such fighter might be to show the way to a country that drops the ball with regard to 2000+ HP engines, but has V-12s that make 1100-1500 HP at higher altitudes than V-1710.

 

[Shortround6]

Maybe you've misunderstood me. I did not said that (X)F4U was able to solve all USAF's worries. I was trying to underline that USAF was some two years behind USN in appreciation of R-2800's potential.
What ever the P-47B was built, it was not up the scratch, because of structural issues and fabric covered ailerons, among other stuff. If the P-47'B' is produced 1st in early 1941, instead of late 1941, that means the Republic can include modifications in order to have a battle worthy P-47'C' in early 1942, instead in autumn of 1942.

Was the Army 2 years behind the Navy? Navy was gambling on an engine that not only hadn't flown yet (in 1938) but would not complete at military type until July 1, 1939. Several months after the the orders for the P-40 and P-39. Please remember that there were two different aircraft with P&W 2 stage supercharged engines at the 1939 fighter trials were the Army picked the P-40 as the winner and Navy two-stage supercharged R-1830s were having operational problems in 1940-41. Granted the Army turbo chargers had problems of their own. The F4U had the Ailerons modified twice, once from XF4U to F4U-1 and again from F4U-1 to F4U-1. Outer wings on F4U behind the mainspar were fabric covered except over the wing bays and the ailerons were plywood covered in fabric for water proofing.

I've never said, in this thread, 'let's build a fighter around a single stage R-2800, that one solves our problems'. I've said: 'is it too early to contemplate about a fighter with turbo R-2800?', to what you replied 'The Turbo R-2800 (P-47) was probably about as quick as could be expected. everybody seems to want miracles.<sinp>'.

The single stage R-2800 fighter seems to be a re-occuring subject. Maybe the Army should try to get a some sort of turbo-charged aircraft into reliable squadron service before worrying about a turbo R-2800

And considering that they ordered those 733 P-47s well before they had the turbo problems sorted out on any service squadron aircraft (early P-38s gave trouble, P-43s gave trouble, early B-17s gave trouble) I am not at all convinced that an earlier introduction of the P-47 (which a number of troubles of it's own) would really have speeded up combat use without resulting in an early combat history like the Typhoons.

The push pull offers performance advantage over all altitudes vs. a conventional twin, due to decreased drag. It will also roll better than a 'classic', because there is no hefty engines on the wings. Pilot has a field of view that is unobstructed by engine nacelles, let alone the booms (vs. P-38 ).
The main shortcoming of early successful US such fighter might be to show the way to a country that drops the ball with regard to 2000+ HP engines, but has V-12s that make 1100-1500 HP at higher altitudes than V-1710.

The push-pull may offer lower drag but how much drag reduction do you need to counter 10-13,000ft difference in full throttle height that the turbos offer? The British had 3 different 2000hp engines, granted they dropped the ball a bit but by the time they did drop the ball a successful (or partially) American push-pull is way too late for the British to design a near copy to use two stage Merlins.

Starting design work in late 1941/early 42 ( when the Vulture has already crashed, the Sabre is one small step away from being canceled and the Centaurus is almost on hold) means the aircraft either misses the war or just barely makes 1945. Work on the DH Hornet started in 1942 with a mock-up being inspected in Jan 1943, first flight in April 1944 and service introduction after the war.

As for the US, the Allison ( and the Continental and Lyoming engines) will NOT take through the prop guns unless you use the P-39 set up. The .50 cal Browning does NOT take to synchronization very well, ( rate of fire being under 500rpm ) so the guns pretty much have to go in the wings, eliminating one of the DO 335 advantages. The US built 3 pushers and had a few more on paper (original P-59 for one) so seemed willing to experiment at times.

 

[tomo pauk]

Was the Army 2 years behind the Navy? Navy was gambling on an engine that not only hadn't flown yet (in 1938) but would not complete at military type until July 1, 1939. Several months after the the orders for the P-40 and P-39. Please remember that there were two different aircraft with P&W 2 stage supercharged engines at the 1939 fighter trials were the Army picked the P-40 as the winner and Navy two-stage supercharged R-1830s were having operational problems in 1940-41. Granted the Army turbo chargers had problems of their own. The F4U had the Ailerons modified twice, once from XF4U to F4U-1 and again from F4U-1 to F4U-1. Outer wings on F4U behind the mainspar were fabric covered except over the wing bays and the ailerons were plywood covered in fabric for water proofing.

I agree that F4U/R-2800 was sort of a gamble in mid 1938. In Autumn of 1939 (when B-26 project received the green light), the R-2800 was acknowledged by Army, it was no more a gamble. Time was ripe to order a fighter with R-2800? Nope, Army was thinking (from J. Baugher's):

The USAAC looked over the proposal [of AP-10] and was favorably impressed. However, they deemed that additional armament would be required, even if it adversely affected performance. Kartveli increased the size of his AP-10 design somewhat, and added four wing-mounted 0.30-inch machine guns. Gross weight rose to 6570 pounds. In this guise, in November 1939 the USAAC ordered one prototype of the AP-10 design under the designation XP-47. The serial number was 40-3051.

Unfortunately, the Army didn't said: 'Mr. Kartveli, why don't you ditch the AP-10 now, and try and design a fighter around turbocharged R-2800' in November of 1939. Almost another 12 months it passed until the firm decision was made about that.

The single stage R-2800 fighter seems to be a re-occuring subject. Maybe the Army should try to get a some sort of turbo-charged aircraft into reliable squadron service before worrying about a turbo R-2800

And considering that they ordered those 733 P-47s well before they had the turbo problems sorted out on any service squadron aircraft (early P-38s gave trouble, P-43s gave trouble, early B-17s gave trouble) I am not at all convinced that an earlier introduction of the P-47 (which a number of troubles of it's own) would really have speeded up combat use without resulting in an early combat history like the Typhoons.

In case the Americans remain true to their standards, the aircraft with weak rear fuselage and problematic ailerons (= P-47B) will never see combat. Once those bugs are ironed out (= P-47C), it will enter the fray, hopefully serving abroad from Summer/Autumn 1942. By then, the turbo should be debugged.
I do agree that most, if not all turbo-equipped aircraft have had problems early on. With reduced numbers of P-43 built (ie. no P-43A), the efforts can be channeled to debug the issues of the P-47. Even if that means stripping the produced P-43s from usable stuff and recycling the rest.

The push-pull may offer lower drag but how much drag reduction do you need to counter 10-13,000ft difference in full throttle height that the turbos offer? The British had 3 different 2000hp engines, granted they dropped the ball a bit but by the time they did drop the ball a successful (or partially) American push-pull is way too late for the British to design a near copy to use two stage Merlins.

Starting design work in late 1941/early 42 ( when the Vulture has already crashed, the Sabre is one small step away from being canceled and the Centaurus is almost on hold) means the aircraft either misses the war or just barely makes 1945. Work on the DH Hornet started in 1942 with a mock-up being inspected in Jan 1943, first flight in April 1944 and service introduction after the war.

I was not thinking about the British, but Germans The two stage Merlin was worth as single stage 2000 HP engine for 20000+ ft missions, and Sabre eventually matured enough.
The US can make a 300 sq ft aircraft that has 2 x ~675 = 1350 HP at 25000 ft, in mid 1940. That is what the granpa Allison, the V-1710 C-15 was offering. The 2-stage R-2800 was producing ~1400 HP at that altitude, but USAF need to wait until mid 1942 to have that power. By that time the new V-1710 will do 2 x 700 = 1400 HP at 25 kft.
We should not forget that plenty of air combat happened under 20000 ft, like at Asia/Pacific, EF and MTO, but also at ETO. The 2800-3200 HP between SL and 10000 FT should come in handy, and at 15000 ft it would be ~2000-2200 HP. Not bad for an aircraft smaller than P-47 or P-38?
Those two can have it at above 25000 ft.
edited to add: the push-pull fighter does not have to worry about problems that plagued early turbo-equipped fighters.

As for the US, the Allison ( and the Continental and Lyoming engines) will NOT take through the prop guns unless you use the P-39 set up. The .50 cal Browning does NOT take to synchronization very well, ( rate of fire being under 500rpm ) so the guns pretty much have to go in the wings, eliminating one of the DO 335 advantages. The US built 3 pushers and had a few more on paper (original P-59 for one) so seemed willing to experiment at times.

Guns will go to the wing, of course. US did built pushers, unfortunately no push-pull fighters were tried.

 

[glennasher]

Considering how many troubles that Vought had with the early Corsairs, it's a wonder it got built at all, the Navy came close (very close) to cancelling it (according to Blackburn's book). It wasn't a worthy aircraft until the F4U-1A, according to Blackburn, and still had a lot of issues, even then.
It takes a long while to iron out problems, especially over-engineered ones, in the field under combat conditions. Even tail-hooks and cowl flaps can cause fits and starts, let alone fabric "flippers" as he called them.

 

[gjs238]

At this point, North American has not been approached about a pursuit aircraft, R-2800 powered or otherwise.
We know that by the time NAA approached the British Purchasing Commission to sell the B-25, NAA was able to come up with the Mustang.
Why do we need to wait for that to happen.
Let's ask NAA earlier. They may give us an Army R-2800 powered pursuit aircraft prior to the F4U-1A and/or P-47, or a V-1710 powered aircraft superior to the P-40 earlier.

 

[tomo pauk]

The NAA can design a fighter around 1-stage Packard Merlin (V-1650-1). The Merlin XX can be provided by the British in order to expedite design test phases. That would provide an affordable 400+ MPH fighter with good range, good punch, no compressibility issues, already in mid 1942 in combat. Once with drop tanks, it can venture into Germany proper.
Alternatively, British may think along these lines: the Lightning with two V-1710 engines, whether turbo or not, is an expensive fighter. Why don't you, NAA, design a fighter around one turbo V-1710?

 

[Shortround6]

I agree that F4U/R-2800 was sort of a gamble in mid 1938. In Autumn of 1939 (when B-26 project received the green light), the R-2800 was acknowledged by Army, it was no more a gamble. Time was ripe to order a fighter with R-2800? Nope, Army was thinking (from J. Baugher's):

The USAAC looked over the proposal [of AP-10] and was favorably impressed. However, they deemed that additional armament would be required, even if it adversely affected performance. Kartveli increased the size of his AP-10 design somewhat, and added four wing-mounted 0.30-inch machine guns. Gross weight rose to 6570 pounds. In this guise, in November 1939 the USAAC ordered one prototype of the AP-10 design under the designation XP-47. The serial number was 40-3051.

Unfortunately, the Army didn't said: 'Mr. Kartveli, why don't you ditch the AP-10 now, and try and design a fighter around turbocharged R-2800' in November of 1939. Almost another 12 months it passed until the firm decision was made about that.

1. In 1939 ALL of the topline fighters in the world were using v-12 liquid cooled engines ( nobody outside of German knew about the Fw 190 and the Japanese fighters weren't considered topline no matter what). Army did not consider the Wildcat as topline. Army had figured that any turbo-charged plane was at least two years away form service use back in the spring of 1939 and on this they were somewhat optimistic. This is why they ordered the P-40s and P-39s, they weren't what the Army wanted in 1939 but what they thought they could get and put into service.
2, From J. Baugher's "On September 13, 1939, the Army ordered eighty examples of the more advanced AP-4J from Republic under the designation P-44" using a turbo R-2180. So maybe the Army figured they had the radial Turbo powered fighter covered?

In case the Americans remain true to their standards, the aircraft with weak rear fuselage and problematic ailerons (= P-47B) will never see combat. Once those bugs are ironed out (= P-47C), it will enter the fray, hopefully serving abroad from Summer/Autumn 1942. By then, the turbo should be debugged.
I do agree that most, if not all turbo-equipped aircraft have had problems early on. With reduced numbers of P-43 built (ie. no P-43A), the efforts can be channeled to debug the issues of the P-47. Even if that means stripping the produced P-43s from usable stuff and recycling the rest.

The main problem was the "turbo-control" which governed the waste-gate. This was NOT built by any of the engine makers and was supplied by the Army (GFE) and until it was sorted out no turbo engine was going to have an acceptable service performance. A few engines did not like turbos anyway ( R-2600 for one).

P-43s served as fighter trainers, ripping them apart to salvage instruments/ linkages and small parts (and engines for (C-47s ?)doesn't get you much.

I was not thinking about the British, but Germans The two stage Merlin was worth as single stage 2000 HP engine for 20000+ ft missions, and Sabre eventually matured enough.
The US can make a 300 sq ft aircraft that has 2 x ~675 = 1350 HP at 25000 ft, in mid 1940. That is what the granpa Allison, the V-1710 C-15 was offering. The 2-stage R-2800 was producing ~1400 HP at that altitude, but USAF need to wait until mid 1942 to have that power. By that time the new V-1710 will do 2 x 700 = 1400 HP at 25 kft.

Germans didn't need any help dreaming up oddball engine installations

Trouble with the Push-pull twin is that you are adding a lot of extra weight. The power plants on the YP-38 weighed 4362lbs without the turbos, engine accessories, or fuel system. The Props on the YP-38 went 693lbs compared to 485lb for a F4U or 541lb for an early P-47D.
Now you need twin booms for a Fokker D 23 type fighter or you need extension shaft and beefed up rear fuselage for a Dornier 335 type plane. XP-39 extension shaft needed a redo ( possible failure at certain RPM due to vibration of engine missfired). P-39 shaft was only about 50lbs but the fuselage was about 50 lbs heavier than a normal fuselage to prevent flex between engine and prop. Do 335 was 45 feet long. If you go much shorter does the airflow from the front prop disrupt the airflow of the second prop much?

We should not forget that plenty of air combat happened under 20000 ft, like at Asia/Pacific, EF and MTO, but also at ETO. The 2800-3200 HP between SL and 10000 FT should come in handy, and at 15000 ft it would be ~2000-2200 HP. Not bad for an aircraft smaller than P-47 or P-38?
Those two can have it at above 25000 ft.
edited to add: the push-pull fighter does not have to worry about problems that plagued early turbo-equipped fighters.

It wont be much smaller than a P-38 and shouldn't be ANY smaller than a P-47. Power plant is heavier than the P-47s power plant and only a few hundred pounds lighter than the P-38s.

 

[tomo pauk]

1. In 1939 ALL of the topline fighters in the world were using v-12 liquid cooled engines ( nobody outside of German knew about the Fw 190 and the Japanese fighters weren't considered topline no matter what). Army did not consider the Wildcat as topline. Army had figured that any turbo-charged plane was at least two years away form service use back in the spring of 1939 and on this they were somewhat optimistic. This is why they ordered the P-40s and P-39s, they weren't what the Army wanted in 1939 but what they thought they could get and put into service.

Not sure from where this came in - I've never said that P-40 and P-39 need to be canceled. Whatever Seversky/Republic produces, that has no bearing on those two fighters.

2, From J. Baugher's "On September 13, 1939, the Army ordered eighty examples of the more advanced AP-4J from Republic under the designation P-44" using a turbo R-2180. So maybe the Army figured they had the radial Turbo powered fighter covered?

There was no questioning 'why we don't have turbo radials in fighters' by me. Army has the P-43 anyway. I simply want the fighter based around the turbo R-2800, the design phase starting much earlier than Summer/Autumn 1940.

The main problem was the "turbo-control" which governed the waste-gate. This was NOT built by any of the engine makers and was supplied by the Army (GFE) and until it was sorted out no turbo engine was going to have an acceptable service performance. A few engines did not like turbos anyway ( R-2600 for one).

Agreed all along.

P-43s served as fighter trainers, ripping them apart to salvage instruments/ linkages and small parts (and engines for (C-47s ?)doesn't get you much.

Okay, we will leave them to the people to do the training, pilots and ground crews alike.

Germans didn't need any help dreaming up oddball engine installations

Trouble with the Push-pull twin is that you are adding a lot of extra weight. The power plants on the YP-38 weighed 4362lbs without the turbos, engine accessories, or fuel system. The Props on the YP-38 went 693lbs compared to 485lb for a F4U or 541lb for an early P-47D.
Now you need twin booms for a Fokker D 23 type fighter or you need extension shaft and beefed up rear fuselage for a Dornier 335 type plane. XP-39 extension shaft needed a redo ( possible failure at certain RPM due to vibration of engine missfired). P-39 shaft was only about 50lbs but the fuselage was about 50 lbs heavier than a normal fuselage to prevent flex between engine and prop. Do 335 was 45 feet long. If you go much shorter does the airflow from the front prop disrupt the airflow of the second prop much?
It wont be much smaller than a P-38 and shouldn't be ANY smaller than a P-47. Power plant is heavier than the P-47s power plant and only a few hundred pounds lighter than the P-38s.

I'd want to go with a Do-335 look-alike - the rear prop would be driven via a shaft. Indeed you're right, the resulting aircraft would not be smaller than P-47.

 

[davparlr]

Now what about the fighters - we might safely assume that P-35/36/40 are to be built. What about the P-43 - is it too early to contemplate about a fighter with turbo R-2800? Hopefully it will feature a wing with only two, but stronger spars, leaving more internal volume free?

The upcoming aircraft, the P-38, P-47, and the P-51 were all excellent aircraft with the ability to carry the USAAC through the entire war. The problem was that they were late in introduction, along with the Navy F4U. The P-39 had promise with good performance in the XP-39, and was easily faster than Axis aircraft when it first flew, albeit not combat ready. However, there was not enough detail design to really optimize the turbo installation. Had this been done, with maybe a slightly longer fuselage, the P-39 may have been a plane to be reckoned with.
Otherwise, lack of engine power, especially at altitude was an issue for all those planes. Without a good supercharger (or turbo-charger) in 1940, the fastest R-1830 powered fighter would probably have been the P-66 with the F4F-3 R-1830-76 engine, which generated 1000 hp at 19k ft. This plane could have made and est. 355 mph at 21k ft which is basically equivalent to the Bf-109E but slower than the F of 1941.
I agree with Shortround that a R-2800 engine would not be much help in the 1940-41 range without an improved supercharger.

About a 2-engined heavy fighter - I'd like to see a classic twin (like DH Hornet), that would be also well suited for both turbo and non-turbo engines (ie. CoG-neutral turbo installation), and between V-12 and radial engines.

I am a bit confused by this question. It sounds like you are describing the P-38. It was a 2-engined heavy fighter that grossed out heavier than the Hornet. Are you talking about something lighter with smaller engines?

 

[tomo pauk]

The P-38 was a twin-boom aircraft, while the DH Hornet was a 'classic' twin.
Smaller engines won't cut it, not just because USA didn't have any V-12s smaller than V-1710.

 

[drgondog]

At this point, North American has not been approached about a pursuit aircraft, R-2800 powered or otherwise.
We know that by the time NAA approached the British Purchasing Commission to sell the B-25, NAA was able to come up with the Mustang.
Why do we need to wait for that to happen.
Let's ask NAA earlier. They may give us an Army R-2800 powered pursuit aircraft prior to the F4U-1A and/or P-47, or a V-1710 powered aircraft superior to the P-40 earlier.

The core P-51 design team comprised of Schmued, Rice and Horkey weren't truly a team until 1939 and the experience they developed to design and make the BC-1 advanced trainer and subsequent NA-50 fighter for Peru in late 1938 was probably a pre-requisite for the P-51. The P-51 got started about as early as possible given the state of NAA in 1936-1939. What 'could have happened' with knowledge we have now is early licensing of the Rolls Merlin and a parallel team to work on what would become the P-51B - with evolution along the lines of the Spitfire as the merlin improved.

By the same token, invest more in a parallel R&D program at Allison to design two stage supercharger for the 1710 but not likely keep pace with Rolls as they closed on the 60 series much earlier than Allison could have achieved.

 

[tomo pauk]

A bit more about bombers: when to start thinking about the bomber powered by two V-12 engines? Most obvious options: install the V-1650, or V-1710 (with turbo or without?) on the A-20; license produce Mosquito; go for the Mixmaster type, but with single stage engines? The V-1710 without turbo was making 1040 HP for take off, 1150 with turbo, available from mid 1940. From mid 1941, the F and E series give 1150 HP for take off, either turbo or not. For comparison, the M-105 used in the early Pe-2 was making 1100 HP for take off, the Twin Wasps were about as good or better. So not much of a true bomber engine yet.
The V-1650-1, available from late 1942/early 1942 (that is, unless we use it on Mustangs ), makes 1300 HP for take off. Mossie put similar RR engines in good use, though for the 4000 lb cookie the 1380 HP (for TO) engines were needed?
From mid 1942, the take off power offered by improved V-1710s is at 1325 HP, and that should make one fast and rangy A-20, and/or could get installed in the license-built Mossie? The WER rating is at almost 1600 HP, but at fairly low 2500 ft (no ram).

 

[tomo pauk]

Maybe someone has definitive data about the XB-42?
Eg. what it was capable when using what engines? The Wikipedia states that 8000 lbs of bombs and 410 mph (without bombs?) were maximum capabilities, but that would be on V-1710-125 engines with 1,325 HP each. OTOH, the -125 engines were not '1325 HP' ones, but were making, according to 'Vee's for victory', 1675 HP for take off with ADI (possibly 1500 HP without ADI?), 1100 HP at 28000 ft (or at 24000 ft; Vee's gives both values) military power and 1900 HP on war emergency with ADI. The -125 was featuring the 12-counterweight crankshaft and, probably, Keystone piston rings, so 3200 rpm was allowed on take off.
To spice up the thing further, the Vee's claims that V-1710-125 was never flown aboard the XB-42, but the V-1710-129 was. Same power, the engine included some improvements from the V-1710-133. The take off power was also at 1675 HP, but now feasible without ADI?
The engines previously used on the 1st XB-42 were the V-1710-103, providing 1325 HP for take off, 1150 HP (or 1200; the Vee's again gives both values) at 22400 ft military power, 1820 HP WER at sea level. Pretty much like the engines used on the P-63A? It is unlikely that 8000 lbs and 410 mph were possibility on such engines. The -125 and -133 were post war engines, and were slated for the 2nd XB-42 prototype.

 

[Shortround6]

Not sure from where this came in - I've never said that P-40 and P-39 need to be canceled. Whatever Seversky/Republic produces, that has no bearing on those two fighters.

It kind of goes back to the original question. What would you do "Knowing" what engines will turn out good and which ones will turn out bad, what grade of fuel will be available when and what it's effect will be, not might be and so on.

OR is the question "what could have done different with only the knowledge of the time?" The "Knowledge" of the time (1937-1940)was that the V-12 fighter had much lower drag than a radial engine fighter.

There was no questioning 'why we don't have turbo radials in fighters' by me. Army has the P-43 anyway. I simply want the fighter based around the turbo R-2800, the design phase starting much earlier than Summer/Autumn 1940.

Actually the Army does NOT have the P-43. It has the design of the P-43 in the spring of 1939. 5 1/2 months before shooting starts in Poland. The first YP-43 is not delivered until Sept 1940, the turning point in the BoB and in the 1 year since the war started ( and 1 1/2 years from being ordered) a lot of ideas about air combat have changed. The P-44 "project" has come and gone being replaced by the R-2800 powered P-47. Now maybe the Army and Kartveli over did it in the armament area but without the knowledge we have now would an earlier P-47 been as we know it or would an earlier P-47 have had a few more "glitches" (cowl guns, handling problems) that needed modification anyway?

Agreed all along

.
Here is something a "time traveler" could sort out. Get the Army to stop using the pressure in the exhaust system to govern the waste gate opening and thus the trubo rpm and pressure in the intake before the carb.
Go to a system that actually measures the intake pressure (which is what was really wanted) and adjusts the waste gate accordingly and ignores the exhaust system pressure ( which is actually irrelevant to what was wanted).

 

[Shortround6]

XB-42 was started about two years after the A-26, in fact it was not started until around 6 months after the XA-26 first flew and in fact it was originally called the XA-42.

Now what did the extra two years bring in regards to airfoils, flaps, structures, etc?

And consider how much more advanced the A-26 was than the A-20 or B-25.

For the US a 2400-2600hp "bomber" doesn't do much and unless you can get the Army to change it's mind they had a policy that only air-cooled engines would be used in attack aircraft at the time in question.

Army requirement that lead to the B-25 called for a top speed of over 300mph, and a range of 2000 miles with a 3000lb bomb load. Early B-25s before the increase in guns could do it. Trying to use 1200-1300hp engines?

 

[tomo pauk]

It kind of goes back to the original question. What would you do "Knowing" what engines will turn out good and which ones will turn out bad, what grade of fuel will be available when and what it's effect will be, not might be and so on.
OR is the question "what could have done different with only the knowledge of the time?" The "Knowledge" of the time (1937-1940)was that the V-12 fighter had much lower drag than a radial engine fighter.

It would be kind a lame 'what-if 'if a good deal of hindsight is not allowed. The what if should be also based upon the realities of a desired countries' historical capabilities.
The Army also has knowledge that a sea-level-rated 2000 HP radial soundly beats the 1150 seal-level-rated V-12. They also know that, once the two V-12s are installed on the wings, every drag advantage (and most of the others, like mileage or cost) of now two V-12s over a single big radial is gone.

Actually the Army does NOT have the P-43. It has the design of the P-43 in the spring of 1939. 5 1/2 months before shooting starts in Poland. The first YP-43 is not delivered until Sept 1940, the turning point in the BoB and in the 1 year since the war started ( and 1 1/2 years from being ordered) a lot of ideas about air combat have changed. The P-44 "project" has come and gone being replaced by the R-2800 powered P-47. Now maybe the Army and Kartveli over did it in the armament area but without the knowledge we have now would an earlier P-47 been as we know it or would an earlier P-47 have had a few more "glitches" (cowl guns, handling problems) that needed modification anyway?

Indeed you're right that the Army does not 'have' the P-43 yet. The 'P-47' certainly won't be a flawless machine, but we can expect that Army wouldn't want the 2000 HP fighter to carry around a feeble amount of armament either. Al least, when looking at what was demanded for the 1100 HP fighters.

Here is something a "time traveler" could sort out. Get the Army to stop using the pressure in the exhaust system to govern the waste gate opening and thus the trubo rpm and pressure in the intake before the carb.
Go to a system that actually measures the intake pressure (which is what was really wanted) and adjusts the waste gate accordingly and ignores the exhaust system pressure ( which is actually irrelevant to what was wanted).

+1 on that.

XB-42 was started about two years after the A-26, in fact it was not started until around 6 months after the XA-26 first flew and in fact it was originally called the XA-42.
Now what did the extra two years bring in regards to airfoils, flaps, structures, etc?
And consider how much more advanced the A-26 was than the A-20 or B-25.
For the US a 2400-2600hp "bomber" doesn't do much and unless you can get the Army to change it's mind they had a policy that only air-cooled engines would be used in attack aircraft at the time in question.

Not trying to advocate a V-12 powered attack aircraft, but a V-12 powered bomber. Sure enough that airfoils and structures improved during the war, the pusher bomber can use the 230 series wing, hopefully not too thick. Scaled up profile from A-20 maybe?

Army requirement that lead to the B-25 called for a top speed of over 300mph, and a range of 2000 miles with a 3000lb bomb load. Early B-25s before the increase in guns could do it. Trying to use 1200-1300hp engines?

B-25 can do that job, in case the enemy air defenses are sub-par, or in case it has fighter cover. The bomber based around 1200-1300 HP V-12s will maybe be capable to carry 3000 lbs at 1500 mile range, while being much less dependent on enemies' porous defenses or allied fighter force. That might or might not be available, or able to escort it when flying against a target 600 miles away?
The 'mosquito' will be also using far less fuel for it's missions, that would be a major bonus once we remember how each gallon of fuel needed to be transported thousands miles away. It will drain less manpower to use it, a reduction of 50-80% vs. B-25/26? It will be faster cheaper to build. It can be a good base to convert it to the night fighter, once the V-1650-1 is available, or turbo or two stage V-1710.

 

[Shortround6]

It would be kind a lame 'what-if 'if a good deal of hindsight is not allowed. The what if should be also based upon the realities of a desired countries' historical capabilities.

Perhaps but a "what if" that has the time-traveler arriving in 1937 (or any other year) to make decisions based not only a general knowledge of history but having a computer full of aeronautical and engine knowledge (airfoils, high lift devices, structures, windtunnel tests, foundry practices, advanced heat treatment and so on and so on) distorts things rather quickly.

The Army also has knowledge that a sea-level-rated 2000 HP radial soundly beats the 1150 seal-level-rated V-12. They also know that, once the two V-12s are installed on the wings, every drag advantage (and most of the others, like mileage or cost) of now two V-12s over a single big radial is gone.

Does it? Without turbos you are actually comparing a 1500hp radial at FTL to a 1150 V-12 at FTL with the FTL's only a few thousand feet apart. And in 1939-40 the Army does not know with 100% certainty that the big radial can be successfully turbo charged. This was reason the Army was developing the Allison and the two Hyper engines, the "wisdom" of the mid 1930s was that the air-cooled engines could not stand up to the needs (cooling) of being turbo charged at high altitudes. By 1940/41 the radials had grown a lot more fin area per cylinder, baffling and cowls got a lot better and the radials (with one exception) turned out to handle the problem pretty well.

Not trying to advocate a V-12 powered attack aircraft, but a V-12 powered bomber. Sure enough that airfoils and structures improved during the war, the pusher bomber can use the 230 series wing, hopefully not too thick. Scaled up profile from A-20 maybe?

Without dictatorial powers the 'time-traveler' isn't going to get the army to buy a new 2400hp bomber (they already have the B-18 and/or the Lockheed Hudson) or a liquid cooled "attack" machine. And they Already have the Airacuda in progress to "show" what kind of performance might be expected.

B-25 can do that job, in case the enemy air defenses are sub-par, or in case it has fighter cover. The bomber based around 1200-1300 HP V-12s will maybe be capable to carry 3000 lbs at 1500 mile range,

Chances are slim and none.

The 'mosquito' will be also using far less fuel for it's missions, that would be a major bonus once we remember how each gallon of fuel needed to be transported thousands miles away. It will drain less manpower to use it, a reduction of 50-80% vs. B-25/26? It will be faster cheaper to build.

Everybody wants to use the 'Mosquito' as model while conveniently forgetting the Mosquito was "designed" around a 1000lb bomb load and turned out to perform above expectations. Mosquito also came together with the Merlin 21 engine and NO Mosquito was flown with a lower powered engine.

I would also note that a B-26B-D can take-off in about the same distance as an A-20 while weighing 5-7000lb more. Yes the B-25 weighs more empty but some of that weight difference in take-off weight is fuel and bombs. Needing two aircraft to deliver the same tonnage of bombs to a target that a single aircraft can doesn't really show much of a savings.

It can be a good base to convert it to the night fighter, once the V-1650-1 is available, or turbo or two stage V-1710.

And here we hit one of my pet peeves with a lot of these "what ifs". "why don't we have air force XXX build airplane YYY with engine QQQ because it will be a fantastic airplane 2 years later when engine ZZZ shows up. Disregarding that plane YYY will be a piece of crap with engine QQQ.

 

[m37b1]

You guys have pretty much nailed this one.

Given that aircraft design advanced at a remarkable rate leading up to, and during the war, it's hard to "do better" than what was done.

Me? I'd have focused on relatively simple changes:

Allison development: Budgeting 2 stage mult-speed mechanical supercharging, development into the program.

Also would have budgeted and pushed for direct injection for all aircraft engines.

Possibly would have pushed for diesel radial development for bombers. (This one's just a dream).

As noted by other's, we can't really eliminate the links of development between 1937 and what we ended up with in 1944, so I'd have made some minor changes to overall standards.

Armaments:

Would have done away with cowl mounded, through the prop, placement.

Engines:

See above

Airframe:

Would have cut down the rear fuselage much sooner, for all around visibility. While the blown plexi bubble, may not have been available in 37, a metal framed canopy could have been incorporated in.

 

[Shortround6]

SOme of your simple changes are not so simple.

Allison needed a LOT more engineers to work on a two stage system, they had the "idea" in 1938 ( about the time P&W filed patents) but their design/engineering staff was way too small. They also had the minor problem of building new factory facilities so they could co form 2-3 engines per month to hundreds of engines a month ( the same design/engineering staff responsible for engine design was also responsible for production tooling design).

Americans need direct fuel injection much less than the British. American Carbs didn't have the "G" problem and later war American carbs were pretty much throttle body fuel injection, Direct fuel injection also calls for hundreds more precision parts per engine.

High powered aircraft diesel engines were a dream.