1941/42: fighter with single stage R-2800, a missed opportunity?

[Shortround6]

I think there is a little something wrong with the time line. The Contract for the P-51A is placed June 23, 1942. two years earlier there are a grand total of 6 R-2800 production engines. 1st production P-51 flies in March of 1943.

Now the performance you want is harder to estimate. So much depends on the drag of the R-2800 installation. At 14-15,000ft you have about 33% more power than a late model Allison but then in 1939 or so an R-1830 had 22% more drag than an Allison in a P-40. How much of the P-51s lower drag compared to the P-40 is due to simple shape? how much due to the wing? how much due to the radiator (Meredith effect)?

The R-2800 is bigger in diameter than the R-1830 and has more frontal area, it is also going to need about 50% more airflow through the cowl for cooling. How much more drag than an R-1830 installation? This is going to eat up some of the HP advantage. There is no (or darn little) Merideth effect from the aircooled engine to offset the cooling drag (at least at this point in time, later installations got better).

Then there is the exhaust thrust question. The Allison certainly has it. Will your fighter? the early F4Us did not with two exhaust out lets down low. The F6F was better but piped the cylinders to grouped outlets just over the wing. You get the most thrust with the highest pressure at the pipe exit. sending the exhaust through 4 ft of pipe tends to slow it down and reduce the pressure. You can chose to use individual exhausts like on a B-25 but adding 18 bumps to the cowl doesn't do much for streamlining.

Then you have the weight question. Considering that this is a new airframe we will forget about the CG and such. But a single stage R-2800 weighs about as much as a 2 stage Merlin with cooling system used in the P-51B&C. The bigger cowl, cowl flaps, engine mounts and such may add another 100lbs.

When all is said and done you are going to wind up with a plane mighty close to 10,000lbs loaded but clean. While the weight may not affect the top speed much it is going affect the climb, altitude and turning.

You have a 10,000lb plane with 1500hp at 14,000ft compared to the F4U 12,000lbs with 1800hp at 15,500ft or 1190hp (?) at 22,500 ft compared to the F4U's 1650hp.

That is pretty much the problem with the concept. There is going to be a very small window of time when the R-2800 is on offer (promised at some point in the future) without the two stage supercharger. After all two different airplanes were using two stage supercharged R-1830s in the Jan 1939 fighter trials. Now how much time and effort do you put into designing and finding manufacturing space for a fighter you KNOW will be second rate just as soon as P&W gets the bugs out of the R-2800 with two stage supercharger?

And just like the problems with the turbo on the P-47, most everybody expected the problems to be sorted out sooner than later.

Once you have tied up millions of dollars in this fighter, how soon can you convert the factory to something else once the two stage engines are available?

 

[gjs238]

An invitation for the discussion: how well would the Allied air forces fared with a fighter made around the single stage R-2800, production starting in second half of 1941 (1733 engines delivered in 1941, per table posted at the AEHS)?

Forget about future R-2800 2-stage development.
Just build a 1-stage land-based fighter.
This is sounding like the land-based F4U threads.

 

[Shortround6]

The problem with forgetting the two stage development is that you are betting the opposing fighters never develop a two stage (or other altitude power boosting system).

Horse power for the A series vs the B series two stage are in a previous post.

The "B" series engine, single stage, offered 2000hp at take off, 2000hp at 1500ft and 1600hp at 13,500ft. 1534hp at 15,500ft and 1255hp at 22,500ft. Having 76% of the power of the two stage engine at 22,500ft is going to call for a a lot of sacrifice in order to offer similar performance. The two stage system, bulky as it was, is certainly not going to suck up the majority of the power difference.

Getting rid of the carrier equipment isn't likely to make up the difference either. Even the folding wings. You may be able to make a better fighter for use from sea level to 15-16,000ft but giving up the higher altitude or depending on P-47s and P-38s for top cover doesn't sound like it is really solving a problem.

 

[tomo pauk]

Surely "2 years earlier than P-51A" is quite a bit earlier than "18 months earlier than the Spit XII"? If it is the latter then the performance will be at about the same time as the P-51A?

Of course, if they don't particularly want the P-51A at the time, would they want the R-2800 equivalent?

Sorry for the time mismatch - I was going after deployment dates (that mens overseas deployment for the P-51A), not the production dates. 'My' fighter should roll of the production lines some time at Jan/Feb 1941.

I think there is a little something wrong with the time line. The Contract for the P-51A is placed June 23, 1942. two years earlier there are a grand total of 6 R-2800 production engines. 1st production P-51 flies in March of 1943.

Thanks for the info, guess I could read that stuff myself.

Now the performance you want is harder to estimate. So much depends on the drag of the R-2800 installation. At 14-15,000ft you have about 33% more power than a late model Allison but then in 1939 or so an R-1830 had 22% more drag than an Allison in a P-40. How much of the P-51s lower drag compared to the P-40 is due to simple shape? how much due to the wing? how much due to the radiator (Meredith effect)?

The R-2800 is bigger in diameter than the R-1830 and has more frontal area, it is also going to need about 50% more airflow through the cowl for cooling. How much more drag than an R-1830 installation? This is going to eat up some of the HP advantage. There is no (or darn little) Merideth effect from the aircooled engine to offset the cooling drag (at least at this point in time, later installations got better).

Then there is the exhaust thrust question. The Allison certainly has it. Will your fighter? the early F4Us did not with two exhaust out lets down low. The F6F was better but piped the cylinders to grouped outlets just over the wing. You get the most thrust with the highest pressure at the pipe exit. sending the exhaust through 4 ft of pipe tends to slow it down and reduce the pressure. You can chose to use individual exhausts like on a B-25 but adding 18 bumps to the cowl doesn't do much for streamlining.

Then you have the weight question. Considering that this is a new airframe we will forget about the CG and such. But a single stage R-2800 weighs about as much as a 2 stage Merlin with cooling system used in the P-51B&C. The bigger cowl, cowl flaps, engine mounts and such may add another 100lbs.

When all is said and done you are going to wind up with a plane mighty close to 10,000lbs loaded but clean. While the weight may not affect the top speed much it is going affect the climb, altitude and turning.

You have a 10,000lb plane with 1500hp at 14,000ft compared to the F4U 12,000lbs with 1800hp at 15,500ft or 1190hp (?) at 22,500 ft compared to the F4U's 1650hp.

Thanks for the numbers estimates.
No quarrels about the 2-stage engine being far superior than the 1-stage. What I'm after is the engine that can beat the 'bread butter' V-1710s and R-1830s of the era, and there (in 1941), the 1 stage R-2800 fits the bill. The 2 stage does not, its some 14 months late.
We can envision the 200 gal fighter, too, in order to bring the loaded weight down to 9000-9500 (more akin to Fw-190As).

That is pretty much the problem with the concept. There is going to be a very small window of time when the R-2800 is on offer (promised at some point in the future) without the two stage supercharger. After all two different airplanes were using two stage supercharged R-1830s in the Jan 1939 fighter trials. Now how much time and effort do you put into designing and finding manufacturing space for a fighter you KNOW will be second rate just as soon as P&W gets the bugs out of the R-2800 with two stage supercharger?

And just like the problems with the turbo on the P-47, most everybody expected the problems to be sorted out sooner than later.

Once you have tied up millions of dollars in this fighter, how soon can you convert the factory to something else once the two stage engines are available?

The key thing for a weapon is not performance, but timing availability. As exemplified by P-38/39/40, F4F, or Hurricane. One thousand of fighters that can make 390 mph in winter of 1941/42 is a far better proposal than one thousand of fighters that can make 410 mph in winter of 1942/43. A simple, available and decent performer is also of far better use for the allies, than a complicated over-performer that is available once the war is almost won.
As for converting a factory to produce something else, seem like that the USA was keen to expand factory space (plus some new factories, like the Eastern aircraft) workforce that was producing fighters making 330-360 mph, so a fighter that can do 390 mph (later 400, with series B engine?) looks like a real winner.
As for unavailability of a design to be updated with the 2 stage variant, the ww2 saw many planes that went from simple engines to 'complicated' heavier ones (Spitfire, P-51, italian series 5 fighters). I can't prove that 'my' fighter can't receive such an upgrade, but dismissing it easily is maybe too much?

 

[Shortround6]

If you "size" the fighter to take the 2 stage engine later you have 15-20 cubic feet of space around the engine doing basically nothing.

View attachment 211130

The center part of the intake at the bottom is intake air for the engine, the outer two intakes are for the inter coolers.

And here we see one of the inter cooling housings. We also see half of the exhaust system.

"The first flight of the XF4U-1 was made on 29 May 1940" It had a two stage engine even if not the same engine as later versions.

So when did Vought first know about the 2 stage R-2800? The mock-up inspection was in February 1939. Construction on actual aircraft starts soon after.

As for the P-47, In June of 1940 Republic is told that The XP-44 and Allison powered XP-47 and 47A are to be dropped and a new plane with the R-2800 is wanted quickly. Sept, 6 1940 Authorization for the P-47B is given as a contract change on the XP-47 contract. In Sept of 1940 the US Army orders a total of 733 P-47Bs and P-47cs off the drawing board. This a couple of weeks before the first P-51 prototype has it's engine delivered.It is also before the first Tomahawk IIA is delivered (export P-40B). It is the same month that the P-40D is first ordered and 10 months before the the first P-40D flies.

Like I said, you have a very, very small window of opportunity in which a single stage R-2800 fighter would be viewed as anything but a temporary expedient and a waste of resources that should be going into the 2 stage-fighters.

 

[Shortround6]

Duplicate.

 

[gjs238]

But the US Army never fielded a R-2800 1-stage fighter.
Perhaps a 1-stage R-2800 fighter would have performed better (air to air, air to ground, etc) than the fighters historically available in the early war years?

 

[tomo pauk]

But the US Army never fielded a R-2800 1-stage fighter.
Perhaps a 1-stage R-2800 fighter would have performed better (air to air, air to ground, etc) than the fighters historically available in the early war years?

More or less that's my point in this thread.

If you "size" the fighter to take the 2 stage engine later you have 15-20 cubic feet of space around the engine doing basically nothing.

View attachment 211130

The center part of the intake at the bottom is intake air for the engine, the outer two intakes are for the inter coolers.

View attachment 211132

And here we see one of the inter cooling housings. We also see half of the exhaust system.

Thanks for the picture, only one is showing?
The intercooler(s) do not need to be located in the airframe proper, but can be located on other places, say, under fuselage, under wing(s), or in front of the leading edges. Saves quite a lot of space. Granted, the 2 stage R-2800 is longer heavier than 1-stage, so maybe the intrercooler (plus the oil cooler) can take the position resembling the P-51 underbelly cooling system.

"The first flight of the XF4U-1 was made on 29 May 1940" It had a two stage engine even if not the same engine as later versions.

So when did Vought first know about the 2 stage R-2800? The mock-up inspection was in February 1939. Construction on actual aircraft starts soon after.

In the same time, the Navy is trying to find out whether the XFL (Airabointa) is of any use, so maybe they were not 100% sure that F4U is as sure thing as the gold at Fort Knox. Actually, both XFL and F4U 1st flew in May 1940.
So for me an 'insurance' fighter seem like an order of a day, more so if we took a look at F2A and F4F situation development (one ordered, even if another is the winner at the contest). The 'insurance' fighter, based around 1 stage, A series R-2800 can be fielded by the Navy/Marines/RAF/FAA etc. a full year earlier than a fighter with 2 stage B series R-2800 (ie. far before the Pearl Harbour happened). It can be produced by Eastern aircraft instead of F4F, too. It can beat anything Japanese get airborne with ease, at least before 1944, while holding it's own vs. German oposition. It can defend Malta other convoys far better than Martlet/Fulmar/Sea Hurricane, while the 2 stager is too late for that.

As for the P-47, In June of 1940 Republic is told that The XP-44 and Allison powered XP-47 and 47A are to be dropped and a new plane with the R-2800 is wanted quickly. Sept, 6 1940 Authorization for the P-47B is given as a contract change on the XP-47 contract. In Sept of 1940 the US Army orders a total of 733 P-47Bs and P-47cs off the drawing board. This a couple of weeks before the first P-51 prototype has it's engine delivered.It is also before the first Tomahawk IIA is delivered (export P-40B). It is the same month that the P-40D is first ordered and 10 months before the the first P-40D flies.

USAAF wants a new plane with R-2800 quickly, yet they opt of the most complicated option. They also opt for the P-63 (June 1941), while Curtiss is busy with XP-46 -60 (despite the orders for the P-47Gs from them) - second thoughts re. P-47 turbo R-2800 itself? Again, the simple 1-stager can be produced from early 1941, so the Allies can use them far earlier than a working turboed R-2800 fighter, yet of far better capabilities than it was possible for the historic US fighters, prior mid 1943.

Like I said, you have a very, very small window of opportunity in which a single stage R-2800 fighter would be viewed as anything but a temporary expedient and a waste of resources that should be going into the 2 stage-fighters.

How big is the window of opportunity can be measured in more ways than one. If your turbo R-2800 fighter enters issues that take time to resolve, firm 2 years of service as one of the top fighters is quite an achievement, even more so if the whole war is 4 years long. If one can equip your allies with a fine performer, the allies can make a better job on their own.
As for the naval bird, it can be ready in service for the major naval actions of 1942, unlike the 2 stager. Even in 1943, it does not like a temporary expedient, but more likely as a fine performer. Far better than the F4F.

 

[wuzak]

The intercooler(s) do not need to be located in the airframe proper, but can be located on other places, say, under fuselage, under wing(s), or in front of the leading edges. Saves quite a lot of space. Granted, the 2 stage R-2800 is longer heavier than 1-stage, so maybe the intrercooler (plus the oil cooler) can take the position resembling the P-51 underbelly cooling system.

For the intercoolers to be remote from the supercharger they either need copious amounts of ducting or to be liquid:air intercoolers. As far as I am aware all the US developed intercoolers were air:air, particularly on air cooled radial applications. Air:air intercoolers require a larger radiator than liquid:air intercoolers.

If you are using a liquid cooled engine the intercooler can be part of the radiator group - as was the case with the P-51. Or it can be mounted remotely - such as on the Mosquito (inlet under the spinner on 2-stage Mossies). Not sure that a designer who has chosen an air-cooled engine will then want to use a liquid:air intercooler.

 

[Shortround6]

The intercooler(s) do not need to be located in the airframe proper, but can be located on other places, say, under fuselage, under wing(s), or in front of the leading edges. Saves quite a lot of space. Granted, the 2 stage R-2800 is longer heavier than 1-stage, so maybe the intrercooler (plus the oil cooler) can take the position resembling the P-51 underbelly cooling system.

Moving them somewhere besides the rear of the engine means they take up more space, not less. Different space but more space, much like the complaints about the P-47 with ducting intake and inter cooler air to and fro in the fuselage. Remember that the P-38 wing leading edge inter-coolers didn't work all that well for powers much over 1000hp per engine and the P-38 had a 52 ft wing. Around 30ft of that was inter-cooler. Look at an F8F, 35 feet of wing span with a fuselage over over 5ft in the middle. You may make it but the wing guns are going to be a problem. Landing gear may or may not be a problem, you may not need it but you just ruled out leading edge fuel tanks.

So for me an 'insurance' fighter seem like an order of a day, more so if we took a look at F2A and F4F situation development (one ordered, even if another is the winner at the contest). The 'insurance' fighter, based around 1 stage, A series R-2800 can be fielded by the Navy/Marines/RAF/FAA etc. a full year earlier............. They also opt for the P-63 (June 1941), while Curtiss is busy with XP-46 -60 (despite the orders for the P-47Gs from them) - second thoughts re. P-47 turbo R-2800 itself? Again, the simple 1-stager can be produced from early 1941, so the Allies can use them far earlier than a working turboed R-2800 fighter, yet of far better capabilities than it was possible for the historic US fighters, prior mid 1943.

Who is left to design/build this fighter? Which historical fighter DOES NOT GET BUILT? Or which bomber?

As an example, Bell (making those P-39s) had 1200 employees in Jan 1940, 5000 Employees in Jan 1941 and 10,000 employees and an additional plant in Dec 1941.

The XP-46 was ordered in Sept 1939., first flight was Jan 1941. XP-50 was ordered in Nov, 1939, first flight Feb 1941. The contract for the Curtiss XP-53 (start of the XP-60 series) was Oct 1 1940. Some rather severe meddling by the Air Corp, coupled with both an inability of the Air Corp to make up their minds what engine to use and Curtiss's apparent inability to get their sums right means that series goes nowhere but quite a bit of work was done before Curtiss ever got a contract for the P-47G.

The P-40 and P-39 are already "interim" fighters, planes the Air Corp will buy until they can get something better. The idea of another interim fighter until the P-38 and P-47 get sorted out seems a bit far fetched. The P-43 was purchased as much to finance Republic factory expansion and to train/enlarge Republic's work force as to get a combat worthy fighter.
The Army may have been a little nuts but in the Fall of 1940 they were ordering things like the XP-56 pusher to try to push the envelope.

Combat reports from the BoB point to the not uncommon altitudes of 25,000-30,000ft at the start of combat, used mostly to bounce aircraft at lower altitudes rather than actual dog fights at those altitudes but still? What will be the needed altitude in 1942-43? 18,000ft or 28,000ft or 33,000ft?

We have the LUXURY of knowing that the Germans and Japanese never developed mass produced propeller planes that could operate (fight) much over 30,000ft and the major exception is the 109. This was certainly not known in 1941/42.

If the US had really wanted a better performing fighter in the Spring/Summer of 1942 at low altitudes all they had to do was approve the WEP power settings earlier.

How big is the window of opportunity can be measured in more ways than one. If your turbo R-2800 fighter enters issues that take time to resolve, firm 2 years of service as one of the top fighters is quite an achievement, even more so if the whole war is 4 years long. If one can equip your allies with a fine performer, the allies can make a better job on their own.
As for the naval bird, it can be ready in service for the major naval actions of 1942, unlike the 2 stager. Even in 1943, it does not like a temporary expedient, but more likely as a fine performer. Far better than the F4F.

It takes about 1 1/2 years from placing the contract ( preliminary drawings/calculations are already done) to first flight of prototype. It takes another 6 months ( at best) to a year to get the first Squadron or two equipped. it takes several more months to work those squadrons up to true fighting capability rather than field targets for the enemy. There are always dozens of little details that need working out.
So you either need to start work in the fall of 1939 to spring of 1940 or you need one of the fastest aircraft design and development programs of WW II. And the engine is only a small part of it. Airframe design was not a sure thing. The Vultee fighter went through 3 different tails. The XP-56 practically refused to take-off. Handling problems with the Helldiver are well known. IF you want a sure thing flight wise it means a "standard" for the time airfoil, a standard configuration and standard construction.

As far as our "allies" doing a better job with it. Our Allies were months ahead of the US in using WEP settings on the Allison and Merlin and had less need of it.

You had also better make up your mind if this is a land fighter or a Naval fighter. The F4F with it's two stage R-1830 was disliked for it's poor altitude performance ( due to weight), it's just that most of the US fighter competition at the time was even worse. The F4F was also disliked for it's poor endurance/range without drop tanks with 144-147 US gallons for it's R-1830 engine. 200 gallons for an ALL PURPOSE R-2800 Naval fighter is too little. The F8F had a definite role to play and high altitude CAP was not it. That role was filled by the F6F-5 and late F4Us. Carrier fighters had to stay airborne much longer than originally planed for a variety of reasons including a crash of a plane ahead of them in the landing pattern/queue having to ditch planes because of not enough fuel is not a good plan. Especially when replacements could be a week or more away.

 

[gjs238]

An invitation for the discussion: how well would the Allied air forces fared with a fighter made around the single stage R-2800, production starting in second half of 1941 (1733 engines delivered in 1941, per table posted at the AEHS)?

Would a Wright R-2600 powered fighter in that time period be more likely timewise?

 

[tomo pauk]

Maybe a fighter built around the R-2600 is upgraded with 1-stage R-2800, in early 1941?

For the intercoolers to be remote from the supercharger they either need copious amounts of ducting or to be liquid:air intercoolers. As far as I am aware all the US developed intercoolers were air:air, particularly on air cooled radial applications. Air:air intercoolers require a larger radiator than liquid:air intercoolers.

If you are using a liquid cooled engine the intercooler can be part of the radiator group - as was the case with the P-51. Or it can be mounted remotely - such as on the Mosquito (inlet under the spinner on 2-stage Mossies). Not sure that a designer who has chosen an air-cooled engine will then want to use a liquid:air intercooler.

Moving them somewhere besides the rear of the engine means they take up more space, not less. Different space but more space, much like the complaints about the P-47 with ducting intake and inter cooler air to and fro in the fuselage.

No quarrels about 2 stage R-2800 needing a decent volume for it's intercoolers associate plumbing. Having a separate 20 ft ducting to 'bring' the air to the intercooler (= P-47) is in stark contrast with P-51 type layout of (not only) intercooler; we need to add there the volume needed for the exhaust gases ducting that obviously was not a part of the mech-supercharged 2 stage R-2800. So we need two pipes, one to and another from the intercooler.

Remember that the P-38 wing leading edge inter-coolers didn't work all that well for powers much over 1000hp per engine and the P-38 had a 52 ft wing. Around 30ft of that was inter-cooler. Look at an F8F, 35 feet of wing span with a fuselage over over 5ft in the middle. You may make it but the wing guns are going to be a problem. Landing gear may or may not be a problem, you may not need it but you just ruled out leading edge fuel tanks.

I do not see the reason to use P-38 type of intercoolers. Mount the same type that were used in the F6F F4U, but just outboard of the leading edge and you're set.

Who is left to design/build this fighter? Which historical fighter DOES NOT GET BUILT? Or which bomber?

As an example, Bell (making those P-39s) had 1200 employees in Jan 1940, 5000 Employees in Jan 1941 and 10,000 employees and an additional plant in Dec 1941.

NAA, Vultee, Severky/Republic, later Easter aircraft, Goodyear, Northrop, Bell?
No P-43, Vengeance, P-63, less B-26s?

The XP-46 was ordered in Sept 1939., first flight was Jan 1941. XP-50 was ordered in Nov, 1939, first flight Feb 1941. The contract for the Curtiss XP-53 (start of the XP-60 series) was Oct 1 1940. Some rather severe meddling by the Air Corp, coupled with both an inability of the Air Corp to make up their minds what engine to use and Curtiss's apparent inability to get their sums right means that series goes nowhere but quite a bit of work was done before Curtiss ever got a contract for the P-47G.

The P-40 and P-39 are already "interim" fighters, planes the Air Corp will buy until they can get something better. The idea of another interim fighter until the P-38 and P-47 get sorted out seems a bit far fetched. The P-43 was purchased as much to finance Republic factory expansion and to train/enlarge Republic's work force as to get a combat worthy fighter.
The Army may have been a little nuts but in the Fall of 1940 they were ordering things like the XP-56 pusher to try to push the envelope.

Thanks for the insight. Army was trying hard with 1200 HP fighters, so a 2000 HP one is hardly a far fetched thing.

Combat reports from the BoB point to the not uncommon altitudes of 25,000-30,000ft at the start of combat, used mostly to bounce aircraft at lower altitudes rather than actual dog fights at those altitudes but still? What will be the needed altitude in 1942-43? 18,000ft or 28,000ft or 33,000ft?

Army expects that it's turbo fighters would do fine. They do not know for sure whether the turbo will be sorted out to work flawlessly, let alone that it would be easily operated by a single person (that should be looking to kill something while flying in war, too). So they give a chance to a plane that can have almost 1000 HP at 30000 ft, or more than twice as the V-1710s that are to be produced from 1939-43.

We have the LUXURY of knowing that the Germans and Japanese never developed mass produced propeller planes that could operate (fight) much over 30,000ft and the major exception is the 109. This was certainly not known in 1941/42.

Agreed.

If the US had really wanted a better performing fighter in the Spring/Summer of 1942 at low altitudes all they had to do was approve the WEP power settings earlier.

Not something I'd agree, on several points.
WEP was not applicable for F4F and F2A (nor F4U/F6F without ADI). For P-39 -40, WEP means high power down low (under 10-12000 ft), so it's rather away from the high altitude mantra. We can take a look at troubles catching IJA/IJN planes flying above mere 15000 ft, and troubles vs. 109/190. WEP was not applicable for the P-40B/C, since the power above 1200 HP would've cracked the reduction gear; for the P-38, the WEP became reality in mid 1943.
As for the WEP itself, it was not just some kind of the switch for pilots to open up when wanting more power. It required testing, approval and increased maintenance, so next time pilot overboosts the engine, it's not damaged. WEP was 5 min rating, military was 15 min rating. The early war US fighters were overweighted when carrying 6 HMG (or P-39s arsenal) plenty of fuel (not P-39, it was not capable for such 'extravaganza'), unlike the 1700+ HP fighters. With 250 gals of fuel, the R-2800 fighter can have it all: range, performance, punch protection, unlike the early types.

It takes about 1 1/2 years from placing the contract ( preliminary drawings/calculations are already done) to first flight of prototype. It takes another 6 months ( at best) to a year to get the first Squadron or two equipped. it takes several more months to work those squadrons up to true fighting capability rather than field targets for the enemy. There are always dozens of little details that need working out.
So you either need to start work in the fall of 1939 to spring of 1940 or you need one of the fastest aircraft design and development programs of WW II. And the engine is only a small part of it. Airframe design was not a sure thing. The Vultee fighter went through 3 different tails. The XP-56 practically refused to take-off. Handling problems with the Helldiver are well known. IF you want a sure thing flight wise it means a "standard" for the time airfoil, a standard configuration and standard construction.

Fair reasonable points.

As far as our "allies" doing a better job with it. Our Allies were months ahead of the US in using WEP settings on the Allison and Merlin and had less need of it.

Allied pilots were surely fighting dying, in hundreds if not thousands, hats of to the men. But, in Europe, 1941-42, they were flying the fighters decidedly inferior to what the LW was fielding. In Asia, they were fighting with, almost, cast offs, while outnumbered. No WEP setting is going to help the P-40 pitted vs. 109F when above 10000 ft, nor the P-39 is going to catch the Betty Zero that are at 15000 ft. The less we talk about Soviet disadvantage in performance, the better. So the Allied pilots were in dire need to forestall the multiple:1 loss ratios, more so than the US ones.

You had also better make up your mind if this is a land fighter or a Naval fighter.

Two similar designs - one naval, another land based.

The F4F with it's two stage R-1830 was disliked for it's poor altitude performance ( due to weight), it's just that most of the US fighter competition at the time was even worse.

Weight had nothing to do with the poor altitude performance - the wing loading was less than of P-39 of P-40. What doomed any performance was the substantial drag - the Cd0 was greater than of P-47, while the wing was of substantial area (260 sq ft). Asking from the R-1830, even the two stager, to make a performer of a draggy airplane is asking too much.
We can note that, in 1942, it was entirely possible to have a fighter with 2000-1500 HP (B series R-2800) vs. 1200-1000 HP (2 stage R-1830), from SL up to 16000 ft, that would be a tad less draggier than the F4F. Couple of carriers more for 1943? Or, for 1941-42 land based aircraft, the demise of the Fw-190?

. The F4F was also disliked for it's poor endurance/range without drop tanks with 144-147 US gallons for it's R-1830 engine. 200 gallons for an ALL PURPOSE R-2800 Naval fighter is too little.

You can note that 250 gals of fuel was my 1st call, not 200 (though the resulting fighter would be a better performer when based around less int. fuel).

The F8F had a definite role to play and high altitude CAP was not it. That role was filled by the F6F-5 and late F4Us. Carrier fighters had to stay airborne much longer than originally planed for a variety of reasons including a crash of a plane ahead of them in the landing pattern/queue having to ditch planes because of not enough fuel is not a good plan. Especially when replacements could be a week or more away.

Fair points; I'm not trying to 'build' a short-burn VF.

 

[Shortround6]

So we need two pipes, one to and another from the intercooler.

Yep. One inlet pipe leading back to the inter cooler from the first stage supercharger and another pipe from the inter cooler back to the second stage. Of roughly the cross section of the middle third of a Hellcats air intake.

I do not see the reason to use P-38 type of intercoolers. Mount the same type that were used in the F6F F4U, but just outboard of the leading edge and you're set.

Well, the F4U may have had the intakes in the wing leading edge but the intercoolers were in the fuselage behind the engine much like the Hellcats. Both planes had substantial wings. Both had landing gear that retracted rearward. A wing the size of the Mustang and using inward retracting gear may be using the wing leading edge and wing root for landing gear wells.

NAA, Vultee, Severky/Republic, later Easter aircraft, Goodyear, Northrop, Bell?
No P-43, Vengeance, P-63, less B-26s?

Thank you for making my point. IF NAA is busy making this thing what aren't they building? British approached NAA becaseu they thought they had spare prodcution capacity or could rapidly build production capacity. Your fighter INSTEAD of the P-51 and not in addition to it? Fewer B-25s? Fewer AT-6s? Not used in combat but there goes some of the later American advantage in better trained pilots.
Same for Severky/Republic only worse, little or no real production capacity, Before the P-43 contract they hadn't built over 100 planes in the companies history. Eastern Aircraft doesn't exist until the spring of 1942. It used 5 or more General Motors car factories ( plus about 3000 sub contractors). Eastern Aircraft never designed an airplane. Same with Goodyear, unless you count blimps. You have got to be kidding with Bell??? I am not sure these guys ever got the predicted numbers right on any fixed wing aircraft.
Maybe fewer P-39s and P-63s would have been a good thing but your fighter is later in timing than the P-39 and if it interferes with P-39 production in 1939/40???
Jack Northrop Split from Douglas and formed his own company (his third) in 1939. Maybe he could have built your fighter, if he wasn't distracted by the XP-56 But again he had no real production facility in 1939/40, The P-61 Black Widow may have been the first production aircraft for the new company.

Vultee? " AVCO hired Dick Palmer away from Howard Hughes to take Jerry's place, and Vultee Aircraft Division began to develop military designs. Dick Palmer created the BT-13, BT-15, and SNV Valiant trainers[2] and oversaw other major production program such as the V-72 Vengeance, serving in the USAAC as the A-31 and A-35. The AVCO Vultee division became the separate Vultee Aircraft Corporation in 1939.[2] The P-66 Vanguard was a 1941 fighter program that was intended for Sweden that was inherited by the USAAC, Great Britain and finally, China. The P-66 had a mediocre combat record in China and was out of service by 1943. The XP-54 fighter project was the last Vultee Aircraft design but only two examples were built." The Vengeance was pretty much Vultee's high point.

We are pretty much back to who is going to design and build it and what do you give up.

Army expects that it's turbo fighters would do fine. They do not know for sure whether the turbo will be sorted out to work flawlessly, let alone that it would be easily operated by a single person (that should be looking to kill something while flying in war, too). So they give a chance to a plane that can have almost 1000 HP at 30000 ft, or more than twice as the V-1710s that are to be produced from 1939-43.

Your almost 1000hp is more like 925hp or so ( for an "A" series R-2800). A Merlin XX should have been good for about 750hp at 30000ft. The two stage R-1830 should have had about 695hp at 30,000ft? How much of that extra 175-230hp is being used to haul around the extra weight and drag of the R-2800 at 30,000ft? And the extra fuel?
"

Not something I'd agree, on several points.
WEP was not applicable for F4F and F2A (nor F4U/F6F without ADI). For P-39 -40, WEP means high power down low (under 10-12000 ft), so it's rather away from the high altitude mantra. We can take a look at troubles catching IJA/IJN planes flying above mere 15000 ft, and troubles vs. 109/190. WEP was not applicable for the P-40B/C, since the power above 1200 HP would've cracked the reduction gear; for the P-38, the WEP became reality in mid 1943.
As for the WEP itself, it was not just some kind of the switch for pilots to open up when wanting more power. It required testing, approval and increased maintenance, so next time pilot overboosts the engine, it's not damaged. WEP was 5 min rating, military was 15 min rating. The early war US fighters were overweighted when carrying 6 HMG (or P-39s arsenal) plenty of fuel (not P-39, it was not capable for such 'extravaganza'), unlike the 1700+ HP fighters. With 250 gals of fuel, the R-2800 fighter can have it all: range, performance, punch protection, unlike the early types.

You originally pitched this idea as better low altitude fighter, in the quoted section of my post I stated "Spring/Summer of 1942 at low altitudes". The British had been using higher than factory recommended boost settings in NA for months ( as did the Flying Tigers) and by the fall of 1942 even US forces had been using higher boost levels at squadron level (unauthorized) and Allison themselves were pushing for higher limits.

The R-2800 powered fighter can have more, the question is how much more and at what altitudes, and is it worth delaying the better aircraft that are in the design/development stage. Considering that both the Germans and Japanese rather dropped the ball in fighter development. The Fw 190 was fine at low altitudes but the 109G was just marking time compared to a 109F. It was better but not enough better and the later "G"s with the higher powered engines were too late in coming. The Japanese took at least two years too long to switch engines in the Zero ( or get rid of the Ki 43). Depending on the enemy to fail to develop better fighters so your "temporary" fighter can show an advantage is not good planning.

Allied pilots were surely fighting dying, in hundreds if not thousands, hats of to the men. But, in Europe, 1941-42, they were flying the fighters decidedly inferior to what the LW was fielding. In Asia, they were fighting with, almost, cast offs, while outnumbered. No WEP setting is going to help the P-40 pitted vs. 109F when above 10000 ft, nor the P-39 is going to catch the Betty Zero that are at 15000 ft. The less we talk about Soviet disadvantage in performance, the better. So the Allied pilots were in dire need to forestall the multiple:1 loss ratios, more so than the US ones.

The Far East and the Soviets were in dire need but they weren't going to get the R-2800 fighter. If the British ship Buffaloes to Singapore in the fall of 1941 instead of MK II Hurricanes or Spitfires what makes you think they would send the few squadrons of R-2800 fighters they were likely to get by then?

The British "ordered 675 of the export version Bell Model 14 as the "Caribou" on the strength of the company's representations on 13 April 1940" "No. 601 Squadron RAF was the only British unit to use the Airacobra operationally, receiving their first two examples on 6 August 1941. On 9 October, four Airacobras attacked enemy barges near Dunkirk, in the type's only operational action with the RAF." Add at least a month or two to get the planes from England to the Far East. First P-39s the Russians got were part of the batch the British decided they didn't want any more. Russians aren't likely to get any unless the British decide they don't want them for first line use. At least not in the fall/winter of 1941/42 and into the spring. The chances of this fighter out performing a MK V Spitfire at altitude are pretty slim.

Two similar designs - one naval, another land based.

More design work???

Weight had nothing to do with the poor altitude performance - the wing loading was less than of P-39 of P-40. What doomed any performance was the substantial drag - the Cd0 was greater than of P-47, while the wing was of substantial area (260 sq ft). Asking from the R-1830, even the two stager, to make a performer of a draggy airplane is asking too much.

It had a lot to do with it. Climb is a reflection of surplus power. Or the power to weight ratio after the power needed to overcome drag is taken out. Now why did the F4F have such a big a wing? Both take-off and landing requirements for carrier operation at the time. These requirements changed as time went on. But in 1939-40 the plane had better land at about the speed of an F4F or the Navy won't buy it. Since this plane is going to weigh about 1 ton more than the F4F it better have a good sized wing. You might be surprised at the difference a few hundred HP can make ( or 1000lbs) to climb in the over 20,000ft area. Navy pilots could tell the difference between F4F-3s, -3As and -4s. All had about the same drag.

 

[wuzak]

No quarrels about 2 stage R-2800 needing a decent volume for it's intercoolers associate plumbing. Having a separate 20 ft ducting to 'bring' the air to the intercooler (= P-47) is in stark contrast with P-51 type layout of (not only) intercooler; we need to add there the volume needed for the exhaust gases ducting that obviously was not a part of the mech-supercharged 2 stage R-2800. So we need two pipes, one to and another from the intercooler

First, the two stage R-2800s did not need to duct the exhaust gasses anywhere. They could use a style of ejector exhaust, or the exhaust collector manifold system.

Second, the ducting to take the air to the intercooler in the P-47 wasn't necessary as such. The P-47 could just as easily have had a rear fuselage mounted scoop to feed the intercooler. The Republic engineers obviously felt their way was better. Note that on the XP-47J the scoop that feed intercooler and supercharger was moved rearwards from the cowl, but remained under the forward fuselage, still requiring lengthy ducting.

 

[wuzak]

The chances of this fighter out performing a MK V Spitfire at altitude are pretty slim.

And by the time it gets manufactured in quantity the Spitfire IX wll be coming out, and widening the altitude performance difference.

 

[tomo pauk]

First, the two stage R-2800s did not need to duct the exhaust gasses anywhere. They could use a style of ejector exhaust, or the exhaust collector manifold system.

Second, the ducting to take the air to the intercooler in the P-47 wasn't necessary as such. The P-47 could just as easily have had a rear fuselage mounted scoop to feed the intercooler. The Republic engineers obviously felt their way was better. Note that on the XP-47J the scoop that feed intercooler and supercharger was moved rearwards from the cowl, but remained under the forward fuselage, still requiring lengthy ducting.

Sure enough that 2 stager did not need the exhaust gases duct, sorry for not being crystal clear. Omitting the exhaust gases ducts when talking/criticizing the P-47 belly duct does blur the picture, though.
When the time comes to upgrade the 1 stage fighter with 2 stage R-2800, the belly scoop featuring the boundary layer splitter is well within the state of the art.

And by the time it gets manufactured in quantity the Spitfire IX wll be coming out, and widening the altitude performance difference.

By the time Spit IX came out, the RAF was already suffered something like 18 months of receiving the multiple:1 losses above W. Europe. Spit IX was not seen as a viable thing to beat Fw-190 under 15000 ft - RAF was fielding the Spit XII and the low level marks of the V to combat the threat, plus the Typhoon. Spit VIII/IX was not, even in late 1943, the most common Spitfire variant in RAF's inventory, let alone in CW air forces. That Spitfire was not able to pursue the outnumbered LW, say, 250 miles away from the Channel (to be fair, not a culprit of the plane itself). What I'm after is a fighter for 1941-42 anyway, not just for late 1942.

 

[tomo pauk]

Well, the F4U may have had the intakes in the wing leading edge but the intercoolers were in the fuselage behind the engine much like the Hellcats. Both planes had substantial wings. Both had landing gear that retracted rearward. A wing the size of the Mustang and using inward retracting gear may be using the wing leading edge and wing root for landing gear wells.

I'm not after the internal intercoolers, but the ones that would protrude from leading edge forward (so not Whirlwind, but Mossie layout).

Thank you for making my point. IF NAA is busy making this thing what aren't they building? British approached NAA becaseu they thought they had spare prodcution capacity or could rapidly build production capacity. Your fighter INSTEAD of the P-51 and not in addition to it? Fewer B-25s? Fewer AT-6s? Not used in combat but there goes some of the later American advantage in better trained pilots.

I'm not making your point. It's about the combined question that I didn't bothered to split up and answer one thing at time.
NAA was capable to design a fighter, any plane they made was an decent- or over-performer. They did not expanded the production lines for the P-51 until the USAAF order came for hundreds of those. Having a plane that attracts USAAF attention and it's ordered in hundred or two, and then the British and French order what's already flying as a prototype, means earlier expansion.
There is no reason that P-51 doesn't came along - flying for the 1st time in late 1942, instead in 1940, with 2 stage Merlin from start.

Same for Severky/Republic only worse, little or no real production capacity, Before the P-43 contract they hadn't built over 100 planes in the companies history.

They can design it. As for the production capacity, there was no way they would expand their production capacity when USAAF orders ~150 planes (= historical P-43). But with USAAF ordering hundreds of planes, they have something to base their future upon, and invest in expansion. Same thing applies for UK French order.

Eastern Aircraft doesn't exist until the spring of 1942. It used 5 or more General Motors car factories ( plus about 3000 sub contractors). Eastern Aircraft never designed an airplane. Same with Goodyear, unless you count blimps. You have got to be kidding with Bell??? I am not sure these guys ever got the predicted numbers right on any fixed wing aircraft. Maybe fewer P-39s and P-63s would have been a good thing but your fighter is later in timing than the P-39 and if it interferes with P-39 production in 1939/40???

Before 'Eastern aircraft etc.' in my reply, you can notice small word 'later'. That means they start the production later. Ditto for Goodyear Bell. No design job for them.

Jack Northrop Split from Douglas and formed his own company (his third) in 1939. Maybe he could have built your fighter, if he wasn't distracted by the XP-56 But again he had no real production facility in 1939/40, The P-61 Black Widow may have been the first production aircraft for the new company.

Darn the XP-56

Vultee? " AVCO hired Dick Palmer away from Howard Hughes to take Jerry's place, and Vultee Aircraft Division began to develop military designs. Dick Palmer created the BT-13, BT-15, and SNV Valiant trainers[2] and oversaw other major production program such as the V-72 Vengeance, serving in the USAAC as the A-31 and A-35. The AVCO Vultee division became the separate Vultee Aircraft Corporation in 1939.[2] The P-66 Vanguard was a 1941 fighter program that was intended for Sweden that was inherited by the USAAC, Great Britain and finally, China. The P-66 had a mediocre combat record in China and was out of service by 1943. The XP-54 fighter project was the last Vultee Aircraft design but only two examples were built." The Vengeance was pretty much Vultee's high point.

Okay, Jack Northrop can design it and start the production in small numbers, with Vultee joining in in production.

We are pretty much back to who is going to design and build it and what do you give up.

We can move on now.

Your almost 1000hp is more like 925hp or so ( for an "A" series R-2800). A Merlin XX should have been good for about 750hp at 30000ft. The two stage R-1830 should have had about 695hp at 30,000ft? How much of that extra 175-230hp is being used to haul around the extra weight and drag of the R-2800 at 30,000ft? And the extra fuel?

US fighter, carrying the Merlin XX (Packard V-1650-1) in the war is a full year late, when compared with the A series R-2800.
What the USAAC thought about the 2-stage R-1830 was clear in 1939 - no fighters with that engine were ordered by intended costumer.

You originally pitched this idea as better low altitude fighter, in the quoted section of my post I stated "Spring/Summer of 1942 at low altitudes". The British had been using higher than factory recommended boost settings in NA for months ( as did the Flying Tigers) and by the fall of 1942 even US forces had been using higher boost levels at squadron level (unauthorized) and Allison themselves were pushing for higher limits.

My idea about the 1-stage fighter was not set in stone by the time the 1st post was made here, but I was looking forward to hear what could be expected from such a plane. Sure enough, the V-12 fighter with 1500 HP, WEP, could beat the radial fighter with 2000 HP under 1000 ft. Problem arises when the 1150 HP fighter is tasked to bring 6 HMGs, 300 miles away, at 20000 ft, beat the performing enemy, and then return. 2000 HP fighter can do that, unlike the 1150 HP fighter.

The R-2800 powered fighter can have more, the question is how much more and at what altitudes, and is it worth delaying the better aircraft that are in the design/development stage. Considering that both the Germans and Japanese rather dropped the ball in fighter development. The Fw 190 was fine at low altitudes but the 109G was just marking time compared to a 109F. It was better but not enough better and the later "G"s with the higher powered engines were too late in coming. The Japanese took at least two years too long to switch engines in the Zero ( or get rid of the Ki 43). Depending on the enemy to fail to develop better fighters so your "temporary" fighter can show an advantage is not good planning.

P-38 will not be delayed, nor should the P-47. The high-tech/high-risk planes will need some time to iron their bugs. The 1-stager can evolve into a 2-stager, even more so since the airframe designers knew rather in advance about the 2 stager.

The Far East and the Soviets were in dire need but they weren't going to get the R-2800 fighter. If the British ship Buffaloes to Singapore in the fall of 1941 instead of MK II Hurricanes or Spitfires what makes you think they would send the few squadrons of R-2800 fighters they were likely to get by then?

Availability of the real performer (instead of the P-39/40) might convince the British to ship more of better indigenous fighters abroad.

The British "ordered 675 of the export version Bell Model 14 as the "Caribou" on the strength of the company's representations on 13 April 1940" "No. 601 Squadron RAF was the only British unit to use the Airacobra operationally, receiving their first two examples on 6 August 1941. On 9 October, four Airacobras attacked enemy barges near Dunkirk, in the type's only operational action with the RAF." Add at least a month or two to get the planes from England to the Far East. First P-39s the Russians got were part of the batch the British decided they didn't want any more. Russians aren't likely to get any unless the British decide they don't want them for first line use. At least not in the fall/winter of 1941/42 and into the spring. The chances of this fighter out performing a MK V Spitfire at altitude are pretty slim.

Maybe it will beat the Spit V, maybe not. Heavy draggy F4U surely outperformed it. So did the much criticized Typhoon.

More design work???

Not really, instead of two separate designs, introduce the Corsair-like folding wings of a tad greater area (270 sq ft vs. 240-250 for the land based plane), hook, some necessary strengthening.

It had a lot to do with it. Climb is a reflection of surplus power. Or the power to weight ratio after the power needed to overcome drag is taken out. Now why did the F4F have such a big a wing? Both take-off and landing requirements for carrier operation at the time. These requirements changed as time went on. But in 1939-40 the plane had better land at about the speed of an F4F or the Navy won't buy it. Since this plane is going to weigh about 1 ton more than the F4F it better have a good sized wing. You might be surprised at the difference a few hundred HP can make ( or 1000lbs) to climb in the over 20,000ft area. Navy pilots could tell the difference between F4F-3s, -3As and -4s. All had about the same drag.

You were 'accusing' the F4F as a too heavy, and I've responded specifically about it. Not about all the planes; the weight was surely the issue for all the planes. A plane that is of a later date than the F4F can have better flap system to help with landing speeds, plus slats. The heavy, but more powerful fighter, that would not be hampered with heavy folding wings, fuel armament, was what the Navy wanted. It was able to outperform the F4F, and 'my' fighter was feasible for them to have in 1941. Sure thing that lighter F-3 was outperforming the heavy F-4, ditto vs. 1-stager F-3A.

 

[Shortround6]

the plane will barely make it for late 1941-early 1942 unless you start work in 1939.

See this web site for a timeline for the Mustang.

P-51 Mustang Timeline

Please note that the British were "accepting" the aircraft in Southern California. They still had to get the aircraft to England. Once in England they had to be reassembled ( from ocean voyage) test flown, and issued to a squadron, once the squadron starts receiving aircraft it can begin conversion training of both pilots and ground crew.
Over 2 years from start of design to first combat operation and this is one of the fastest programs of the war. By the time the first planes see combat about 500 have rolled out the factory door.

Any R-2800 powered fighter would pretty much follow the same or a longer time line. In 1940 the 5th production R-2800 was delivered in March but only 17 engines were delivered in all of 1940.

It took roughly (an average) one year from the 5th production example until the 1000th was delivered.

How many fighters do you want IN SERVICE in the Spring of 1942? The 1000th P-51 was not delivered/accepted at the factory) until Jan 1943.

 

[tomo pauk]

the plane will barely make it for late 1941-early 1942 unless you start work in 1939.

Agreed.

See this web site for a timeline for the Mustang.

P-51 Mustang Timeline

Please note that the British were "accepting" the aircraft in Southern California. They still had to get the aircraft to England. Once in England they had to be reassembled ( from ocean voyage) test flown, and issued to a squadron, once the squadron starts receiving aircraft it can begin conversion training of both pilots and ground crew.
Over 2 years from start of design to first combat operation and this is one of the fastest programs of the war. By the time the first planes see combat about 500 have rolled out the factory door.

Thanks; fair points there.

Any R-2800 powered fighter would pretty much follow the same or a longer time line. In 1940 the 5th production R-2800 was delivered in March but only 17 engines were delivered in all of 1940.
It took roughly (an average) one year from the 5th production example until the 1000th was delivered.
How many fighters do you want IN SERVICE in the Spring of 1942? The 1000th P-51 was not delivered/accepted at the factory) until Jan 1943.

Prior 1942, more than 1700 of R-2800s were delivered. Granted, delivered engine does not mean that an aircraft carrying it is at the front line. I'd go for the figure of 800-900 planes produced during 1941; combat losses make it hard to estimate how many planes would be in service during any time frame.

 

[wuzak]

Prior 1942, more than 1700 of R-2800s were delivered. Granted, delivered engine does not mean that an aircraft carrying it is at the front line. I'd go for the figure of 800-900 planes produced during 1941; combat losses make it hard to estimate how many planes would be in service during any time frame.

What aircraft used them in that period? The Martin B-26 was one, certainly.