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

[davparlr]

Technically, I see no reason that the AAF could not field a capable R2800 "A" engine fighter in January, 1942, that would outperform or equal both the Fw-190A-3 and the Bf-109F-3 at altitudes up to 15-20k ft. Above 20k ft. competing would be problematic. To accomplish this, several criteria would have to be met. One, the AAF would have to actively desire and pursue such an effort, two, procurement efforts would have to start in early, 1939, about the same time as the B-26 effort, and three, manufacture of the R2800 would have to be well planned in order to not significantly affect the other R2800 programs. Some programs may need to be delayed such as the C-46, which would hurt "The Hump", but the C-47 was still a very capable transport. Priorities would have to be made.

This aircraft would be 9-10k lbs weight, somewhere between the Fw-190A-3 and A-5 and could carry four .50 Cals ala F4F, P-51B, F8F. Wing area would be around 200 – 220 sqft. and similar to the Fw-190 in weight and power. It would have been designed to accept the "B" engine, say the dash 8 (Corsair). Designing aircraft to growth is not unusual; I believe the F6F was designed to accept a turbocharger. It would add little to the aerodynamics and slightly to the weight. In fact, one possibility would be to design in adaptability to add fuselage inserts to modify CG like the Fw-190D had to do. The upgraded aircraft could be operational Jan. 1943, almost a year before the P-51B arrived, and provide very good performance to a reasonable altitude. This would provide a better performer than a land based Corsair and could possibly expanded in range to give pretty good escort capability but still not as good as the P-51 did.

I would start with the P-66, a clean aircraft with a amazing similarity to the F4U, and 10-20 mph faster than contemporaries with same engine and good flying qualities. It has some problems but I think just needed development time. Rebuild to fit the R2800 to above requirements.

You either design a bigger than needed ( and poorer performing) fuselage/airframe to take the two stage installation later or you design a smaller tighter better performing aircraft for the single stage engine

It would probably only be length, which would have little effect on airspeed and some weight, unless, of course you can insert fuselage splices.

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.

It was fast and handled well. There were significant problems in China from being in a second class war to second class pilots to second class logistics, even P-40s were delivered without components. No comparison to the well flown and well maintained, but slower and slower climbing F4F-3s. Many contemporary aircraft was having performance trouble with the Japanese at the beginning of the war. It is interesting to note that one of the complaints of the pilots was that it had too high a wing loading, which happened to be less than the Fw-190's wing loading. Poor advanced thinking and training that also plagued the B-26.

 

[wuzak]

This aircraft would be 9-10k lbs weight, somewhere between the Fw-190A-3 and A-5 and could carry four .50 Cals ala F4F, P-51B, F8F. Wing area would be around 200 – 220 sqft. and similar to the Fw-190 in weight and power. It would have been designed to accept the "B" engine, say the dash 8 (Corsair).

The dash 8 was a two stage engine.

I believe the F6F was designed to accept a turbocharger.

Don't think so. The F6F was originally designed to use the R-2600, but soon changed to the R-2800, and in production used the R-2800-10, which was the same as the -8, except that one had updraft carbies and the other downdraft carbies.

 

[davparlr]

The dash 8 was a two stage engine.

That is why the plane would need to be either more growth space or fuselage inserts. I believe the dash 8 is a "B" engine. This is the engine I meant to have growth to. I should have stated growth for a two stage supercharged "B" engine.

Don't think so. The F6F was originally designed to use the R-2600, but soon changed to the R-2800, and in production used the R-2800-10, which was the same as the -8, except that one had updraft carbies and the other downdraft carbies.

Per wikepedia and other sources:

Other prototypes in the F6F series included the XF6F-2 (66244) and F6F-3 which was converted to use a turbo-charged Wright R-2600-15, which was later replaced by a turbo-charged Pratt Whitney R-2800-21. The performance proved not to be as good as was expected and the turbo chargers proved to be unreliable on both engines:

 

[Shortround6]

Technically, I see no reason that the AAF could not field a capable R2800 "A" engine fighter in January, 1942, that would outperform or equal both the Fw-190A-3 and the Bf-109F-3 at altitudes up to 15-20k ft. Above 20k ft. competing would be problematic.

While you could, in theory, field a R-2800 "A" engine by Jan 1942 it would be in small numbers, large numbers coming later. This may be OK as the Fw 190 is only available in small numbers. The devil, as always, is in the details. The R-2800-5 offers more power, especially for take off. at 14-16,000ft the difference is some what less, especially when the 801 D engine shows up. 1440hp at 18,700ft? vs 1500hp at 14,000ft. The DiD (devil in details) is that the R-2800 is as big "naked" as the BMW 801 is with cowling. The P&W cowlings were not as advanced as the BMW cowling which means you have more drag. How much more?
2nd DiD, Fw 190 carried 524liters of internal fuel or 138.5 us gallons or 831lbs. The P-39 carried 120 gallons, the P-40 could hold a bit over 150 gallons internal, the Wildcat went about 144 gallons. The F8F went 185 gallons or 1110lbs of fuel. Some posters in this thread have said 200 US gallons (1200lbs) to 250US gallons for a carrier version (1500lbs) And it is not just the weight of the fuel, some of which will be burned off before combat. It is the weight of the larger tanks and perhaps the the larger structure needed to hold the larger tanks. 140 gallons vs 195 gallons?? Look at standard US 55 gal drum.
Will the US accept an R-2800 fighter with close to the Fw 190s fuel tankage/range/endurance?
3rd DiD, wing size. anywhere from about 200sq ft to 270sq ft has been mentioned. The Fw 190 wing was just under 200sq ft. as a rough rule of thumb a 25% larger wing might cost 3% of top speed, every thing being as close to equal as possible. That is a loss of 12mph for the 250sq ft wing? Now maybe you don't need the 250sq ft wing if you keep the fuel down below 185 gallons (F8F had 244 sq ft wing)
4th DiD. Armament weight. The Fw 190 carried 310kg worth of guns and ammo if it had the MG FF cannon in the outer wings. A P-40E carried 332kg of guns and ammo. Actual armament weight can vary due to weights of mounts, gun chargers, feeds, chutes, ammo boxes and ammo links. Does anybody really think if you present the US Army with an R-2800 powered fighter plane in 1939-40-41 that they are only going to stick four .50 cal guns in it?
One .50 weighs 29kg. One MG 151/20 weighs 42kg. One round of .50 cal ammo goes about 112grams (give or take depending on bullet). One round of 20 X 82mm ammo goes 183-205 grams depending on projectile.
Four .50s while usable (many Fw 190s were shot down with such an armament) is definitely inferior to the Fw 190s armament even if you take out the wing 20mm MG FFS.

It would have been designed to accept the "B" engine, say the dash 8 (Corsair).

The "B" engine followed hard on the heels of the "A" and in both the P&W Hartford Factory and at Ford it was like flipping a switch. But this is the single stage "B" engine. 2000hp for take off and 1600hp at 13,500ft. P&W builds 2 in 1941 and then 220 in Jan 1942, "A" production drops from 270 in Nov to 263 in Dec to 49 in Jan and stops. Feb 1942 sees 359 "B" single stage engines built. Ford flipped the switch a few months later. They averaged about 230 "A" engines a month for Jan, Feb, Mar of 1942 while building up to 150 "B"s in March. April sees zero "A"s but 463 "B"s Ford never builds a two stage engine but many of those "B"s go into P-47s.

I would start with the P-66, a clean aircraft with a amazing similarity to the F4U,

only in general outline. Sticking a 2000hp 2400lb engine with a 13 ft propeller on a modified trainer (bit of an exaggeration but the P-66 is to the Vultee trainer series what the Boomerang was to the AT-6) is going to call for a bit more than a little development.

 

[Shortround6]

Some US production numbers;

Type............................1940...............1941....................1942.................1943

P-40..............................778...............2246....................3854.................4258
P-39...............................13.................926....................1932.................4947
F4F (and FMs).................106................324.....................1470................1537

P-38...............................1..................207.....................1479.................2497
P-51...................................................138......................634.................1710
P-47.....................................................1.......................532.................4428
F4U................................1.............................................178.................2293
F6F................................................................................10..................2547

getting R-2800 powered planes overseas to the Philippines, Singapore, The Dutch East Indies,etc. is going to be near impossible before the Japanese attack. The Flying Tigers P-40s were placed on board ship in June or July of 1941 and went into combat after Pearl harbor. The Summer of 1942 is a much more likely combat debut for such an airplane as evidenced by the first combat use of the Mustang and the use of four squadrons at Deippe in August.
Now how many months between combat debut and making a real difference in theater?
Gloster delivered 250 Typhoons between Sept 1941 and June 1942.
The F4U was "rushed" into service in Jan/Feb 1943.

The US had a policy of working up units in the US on the combat type they would use in combat BEFORE shipping them overseas. In the case of the P-47s, the first units in the US got the P-47Bs and trained for several months. When ready to ship out they were issued factory fresh P-47Cs and the P-47sBs passed to a new squadron that was forming up.
Sending new units into combat with untried aircraft is an excellent way to run up enemy scores. Many US aircraft having trouble with their .50 cal guns, not because of any trouble with the guns ( or darn little) but because in peace time training flights the ammo trays had seldom been filled to anywhere near full.WIth full loads the ammo shifted in flight and jammed the guns. Lots of little, relatively easy to fix problems can crop up with any new aircraft, The first few using squadrons are essentially the "beta" testers for the aircraft and help write/rewrite the manuals for later squadrons.
The "fact" that you might be able to have 2-300 R-2800 "A" powered fighters manufactured by Dec of 1941 doesn't mean that you have 10-15 combat squadrons.
You have about a 9 month "window" for combat use before the P-47 and F4U start pushing a single stage engine fighter out of the picture.

And what have you given up to get it?

If you have Vultee make it-------- " France placed an order for 300 V-72s, with deliveries intended to start in October 1940. The fall of France in June 1940 stopped these plans, but at the same time the British Purchasing Commission.... was shopping for a dive bomber for the Royal Air Force, and as it was the only aircraft available, placed an order for 200 V-72s (named Vengeance by Vultee) on 3 July 1940, with orders for a further 100 being placed in December.[3] As Vultee's factory at Downey was already busy building BT-13 Valiant trainers, the aircraft were to be built at the Stinson factory at Nashville,[a] and under license by Northrop at Hawthorne, California.[2]
The first prototype V-72 flew from Vultee's factory at Downey, California on 30 March 1941. The first RAF squadrons (No. 82 and No. 110) received Vengeances in October 1942. The first dive bombing missions against Japanese forces were flown on 19 March 1943.

Australia placed an order for 400 Vengeances as an emergency measure following the outbreak of war in the Pacific,[13] which was met by a mixture of Lend Lease and diversions from the original British orders.[5] While the first Vengeance was delivered to the Royal Australian Air Force (RAAF) in May 1942, the aircraft did not arrive in substantial numbers until April 1943. No 12 squadron of the RAAF was the first RAAF squadron to get the Vengence. No. 12 Squadron began to be re-equipped with Vultee Vengeance dive bombers from October 1942."

Now The British may have changed their minds (waffled) about deploying the Vengeance in Europe or the Middle East and delayed things a bit, But it looks like having Vultee build the R-2800 "A" fighter gets it to the squadrons in late summer of 1942 at best and into combat in the fall.

Sorry guys, but I don't think the performance, while better tha a P-40 or P-39 is in the equal of the Fw 190 and I don't think it would see significant action until the fall/winter of 1942.

 

[wuzak]

Per wikepedia and other sources:

Other prototypes in the F6F series included the XF6F-2 (66244) and F6F-3 which was converted to use a turbo-charged Wright R-2600-15, which was later replaced by a turbo-charged Pratt Whitney R-2800-21. The performance proved not to be as good as was expected and the turbo chargers proved to be unreliable on both engines:

Key word is converted. Not designed.

 

[davparlr]

While you could, in theory, field a R-2800 "A" engine by Jan 1942 it would be in small numbers, large numbers coming later. This may be OK as the Fw 190 is only available in small numbers. The devil, as always, is in the details. The R-2800-5 offers more power, especially for take off. at 14-16,000ft the difference is some what less, especially when the 801 D engine shows up. 1440hp at 18,700ft? vs 1500hp at 14,000ft.

No argument here and not incompatible with what I said.

The DiD (devil in details) is that the R-2800 is as big "naked" as the BMW 801 is with cowling. The P&W cowlings were not as advanced as the BMW cowling which means you have more drag. How much more?

I need to see some data here. With photographs and my trusty scale the comparison between the cowlings F4U and the Fw-190 does not indicate a large difference in cowling diameter beyond the diameter of the engines, 51" for the BMW and 53" for the P&W. Admittedly that is eyeballing it with associated error, but enough question to request specific data.

2nd DiD, Fw 190 carried 524liters of internal fuel or 138.5 us gallons or 831lbs. The P-39 carried 120 gallons, the P-40 could hold a bit over 150 gallons internal, the Wildcat went about 144 gallons. The F8F went 185 gallons or 1110lbs of fuel. Some posters in this thread have said 200 US gallons (1200lbs) to 250US gallons for a carrier version (1500lbs) And it is not just the weight of the fuel, some of which will be burned off before combat. It is the weight of the larger tanks and perhaps the the larger structure needed to hold the larger tanks. 140 gallons vs 195 gallons?? Look at standard US 55 gal drum.
Will the US accept an R-2800 fighter with close to the Fw 190s fuel tankage/range/endurance?

I don't see fuel as an issue. The F4U carried 237 gallons in the fuselage. No, the AAF would not accept the limited performances used in the German and British aircraft, but it is always a tradeoff.

3rd DiD, wing size. anywhere from about 200sq ft to 270sq ft has been mentioned. The Fw 190 wing was just under 200sq ft. as a rough rule of thumb a 25% larger wing might cost 3% of top speed, every thing being as close to equal as possible. That is a loss of 12mph for the 250sq ft wing? Now maybe you don't need the 250sq ft wing if you keep the fuel down below 185 gallons (F8F had 244 sq ft wing)

I don't see the issue you here. The Fw-190A-5 grossed out at 10k+ with a wing area of 197 sqft. The Ta-152C grossed out at almost 12k lbs and had a wing area of 210 sqft. It depends on what you want to do with the plane.

4th DiD. Armament weight. The Fw 190 carried 310kg worth of guns and ammo if it had the MG FF cannon in the outer wings. A P-40E carried 332kg of guns and ammo. Actual armament weight can vary due to weights of mounts, gun chargers, feeds, chutes, ammo boxes and ammo links. Does anybody really think if you present the US Army with an R-2800 powered fighter plane in 1939-40-41 that they are only going to stick four .50 cal guns in it?

Probably not. But I don't see the issue here. It depends on what the AAF wants to do with the aircraft. If they want the best performance, they could lighten the load. It is the trade off every aircraft designer had to make.

only in general outline. Sticking a 2000hp 2400lb engine with a 13 ft propeller on a modified trainer (bit of an exaggeration but the P-66 is to the Vultee trainer series what the Boomerang was to the AT-6) is going to call for a bit more than a little development.

I am not sure of this comment. It seems to imply that if a fighter design is associated with a trainer the fighter is somehow inferior even if it meets the fighter design requirements. My experience with trainer aircraft is that they tend to be rugged designs to endure continued abuse by student pilots, and were often converted into successful combat designs. The T-38/F-5 family of aircraft is one example that a fighter and a trainer can be successfully made from the same design effort. Other trainers converted to successful combat aircraft were the T-28 and the T-37/A-37. The A-37 even had a more powerful engine.
I don't think there is any more evidence that the p-66 was a "modified" trainer than there is to say the BT-13 is a "modified" fighter. Rather it seems both had independent design teams.

While you are right that a lot of design effort was required, this was also true with the B-26 in the same time period and it was operational by Jan. 42.

Sorry guys, but I don't think the performance, while better tha a P-40 or P-39 is in the equal of the Fw 190 and I don't think it would see significant action until the fall/winter of 1942.

I disagree. I believe this fighter could have been fielded near the same time as the similarly powered but more complex B-26. 57 B-26s arrived in Australia February 26, 1942 and commenced training and began operation against Japan in the spring of '42. In addition, 52 had already been delivered to the British. In June, 1942, four B-26s ran operations against the Japanese at Midway. If an aircraft as complex and revolutionary as the B-26 could have started development in 1939 and fielded a significant number by Spring, 1942, it is not unreasonable to believe a simpler fighter with similar production emphasis could also be in operations in Pacific in even more significant numbers. This may involve delaying the B-26. But, the B-25 was a reasonably capable replacement for the B-26.

I agree with you that this version, while having some advantages over contemporary aircraft would not add much. I am not sure that this would have provided much improvement at all over the P-51/A in the same time period. However a two stage version in January, '43, would have been quite helpful in ETO in operations against the Fw-190A-4/5s and Bf-109Fs and Gs, certainly below 25k, maybe higher, before the P-51Bs showed up.

 

[davparlr]

Key word is converted. Not designed.

However, the installation of a turbosupercharger on a 2600 or 2800 engine is no trivial matter, just look at installation on a P-47. The F6F-2 with the 2600 engine was an early bird and it is unreasonable to doubt that some thought and design decisions went into making this major modification available during development. Just having the excess available space for the turbo and ducting would have been an anathema to aerodynamicist, weights and balances engineer, manufacturing, costs analyst, etc., etc.

 

[tomo pauk]

If I may:

While you could, in theory, field a R-2800 "A" engine by Jan 1942 it would be in small numbers, large numbers coming later. This may be OK as the Fw 190 is only available in small numbers.

By July 1st 1941, 400+ of the R-2800 were produced. Meaning 400+ of thee fighters deployed overseas by Jan 1942?

The devil, as always, is in the details. The R-2800-5 offers more power, especially for take off. at 14-16,000ft the difference is some what less, especially when the 801 D engine shows up. 1440hp at 18,700ft? vs 1500hp at 14,000ft.

The devil is, indeed, in details. The BMW-801D was restricted in all ratings, prior late 1942. That means that, eg. 'Notleistung' (3 min rating) was allowed to be made under 1,35 ata and 2450 rpm ('stead of 1,42 and 2700 rpm), or roughly comparable with 'Steig und kampflesitung'. So no 1440 HP at 18700 ft, but maybe 1320 HP. Sure enough, the things can get interesting for the 190A once the 3 minutes of Notleistung are out; the R-2800 has, ideally, some 12 minutes left to use it's military power (used here for comparison of engine power).
The power deficit under 15000 ft is 150-300 HP vs. the A series, and, under 13500 ft, is 250-450 HP vs the B series. Only above 17000 ft the restricted 801D equals the 1 stage R-2800s.

The DiD (devil in details) is that the R-2800 is as big "naked" as the BMW 801 is with cowling. The P&W cowlings were not as advanced as the BMW cowling which means you have more drag. How much more?

Fair points.

2nd DiD, Fw 190 carried 524liters of internal fuel or 138.5 us gallons or 831lbs. The P-39 carried 120 gallons, the P-40 could hold a bit over 150 gallons internal, the Wildcat went about 144 gallons. The F8F went 185 gallons or 1110lbs of fuel. Some posters in this thread have said 200 US gallons (1200lbs) to 250US gallons for a carrier version (1500lbs) And it is not just the weight of the fuel, some of which will be burned off before combat. It is the weight of the larger tanks and perhaps the the larger structure needed to hold the larger tanks. 140 gallons vs 195 gallons?? Look at standard US 55 gal drum.
Will the US accept an R-2800 fighter with close to the Fw 190s fuel tankage/range/endurance?

No quarrels about the fuel situation it's repercussions. US doctrine 'orders' it's fighter force to go out kill. The defender (say, Fw-190 on Western front, from mid 1941 on) is the one that need to climb fast, not the attacker, already at 15-20000 ft. The 1/4 larger wing is there to help with wing loading - that being more favorable than with P-51D. Also, the Fw-190A5 at 8800 lbs (loaded, clean) with wing of just under 200 sq ft and a single stage engine does not direct us toward a great above-20000 ft fighter?

3rd DiD, wing size. anywhere from about 200sq ft to 270sq ft has been mentioned. The Fw 190 wing was just under 200sq ft. as a rough rule of thumb a 25% larger wing might cost 3% of top speed, every thing being as close to equal as possible. That is a loss of 12mph for the 250sq ft wing? Now maybe you don't need the 250sq ft wing if you keep the fuel down below 185 gallons (F8F had 244 sq ft wing)

How well was the Fw-190A served by it's wing? Great for combats under 15000 ft (low drag due to size, NOT shape), but offering unfavorable wing loadings above 20000 ft? The R-2800 fighter need thinner wing, something between Spitfire's and Tempest's. We do not want another Typhoon wing mistake here, nor there is the need for the huge wings of the USN birds.

4th DiD. Armament weight. The Fw 190 carried 310kg worth of guns and ammo if it had the MG FF cannon in the outer wings. A P-40E carried 332kg of guns and ammo. Actual armament weight can vary due to weights of mounts, gun chargers, feeds, chutes, ammo boxes and ammo links.
Does anybody really think if you present the US Army with an R-2800 powered fighter plane in 1939-40-41 that they are only going to stick four .50 cal guns in it? One .50 weighs 29kg. One MG 151/20 weighs 42kg. One round of .50 cal ammo goes about 112grams (give or take depending on bullet). One round of 20 X 82mm ammo goes 183-205 grams depending on projectile.
Four .50s while usable (many Fw 190s were shot down with such an armament) is definitely inferior to the Fw 190s armament even if you take out the wing 20mm MG FFS.

6 HMGs for me, thanks

The "B" engine followed hard on the heels of the "A" and in both the P&W Hartford Factory and at Ford it was like flipping a switch. But this is the single stage "B" engine. 2000hp for take off and 1600hp at 13,500ft. P&W builds 2 in 1941 and then 220 in Jan 1942, "A" production drops from 270 in Nov to 263 in Dec to 49 in Jan and stops. Feb 1942 sees 359 "B" single stage engines built. Ford flipped the switch a few months later. They averaged about 230 "A" engines a month for Jan, Feb, Mar of 1942 while building up to 150 "B"s in March. April sees zero "A"s but 463 "B"s Ford never builds a two stage engine but many of those "B"s go into P-47s.

Thanks for the info. Some 11000 of the R-2800s produced in 1942?

 

[Shortround6]

On the power issue. BMW information from the 1946 "Jane's" corrections welcome. followed by information from an article in Nov/ and Dec 1942 editions of "Aviation Magazine". Article available at the AEHS website. of P&W information from company Data sheets at the AEHS website.

BMW 801C take off and sea level emergency power 1600hp/2700rpm/1.32AtA. 1380hp/2700rpm/1.3AtA at 15,100ft.
Climbing power, 1460hp/2400rpm/1.25 at sea level. 1310hp/2300rpm/1.25AtA at 14,500ft.
Max Cruise, 1230hp/2300rpm/1.15AtA at sea level. 1170hp/2300rpm/1.15 ATA at 15,000ft.

From the magazine, engine report seems to be on a Do 217E engine. Maximum power for takeoff for 3 min. -- 1,580bhp. @ 2,700 rpm. @ 4.7 psi. manifold pressure.
Maximum power (emergency) – 1.585 bhp. @2,550 rpm. @ 15,750 ft. @ 4.5 psi manifold pressure.
Maximum cruising power (continuous) – 1,280bhp. @ 2,300 rpm. @ 18,500 ft. @ 2.2 psi manifold pressure.

Size of engine given as 50in with 52in being the diameter of the cowling.

"Jane's" numbers for the 801D

T-O and Emergency at sea level. 1700hp/2700rpm/1.42ata. 1440hp/2700rpm/1.42ata/18,70ft.
Climb power 1500hp/2400rpm/1.32ata sealevel and 1360hp/2400rpm/1.32ata /17,000ft.
Max cruise 1300hp/2300rpm/1.2ata /sea level and 1215hp/2300rpm/1.2ata/18,000ft.


P&W R-2800-5 (as used in the B-26)
Take off power. 1850hp/2600rpm Military power 1850hp/2600rpm/2700ft and 1500hp/2500rpm/14000ft.
"Normal" Power. 1500hp/2400rpm/7500ft and 1450hp/2400rpm/13,000ft.
Diameter of engine given as 52.06in.

The 1944 edition of "Aircraft Engines of the World" has these figures but adds 49in MAP for take-off which seems in line. No other manifold pressures found so far.

If somebody knows where to find a B-26 manual for the early planes with the -5 engine it would be very helpful.

Edit> found the manual in the manual section. It does not have a specific engine chart like later manuals. but does give limits of operation.
Take-off-Auto-rich Low blower only, 2600rpm, 49in M.P. Military power-auto-rich Low blower 2600rpm 49in M.P. High blower 2600rpm 40.5in M.P.

"B" series R-2800-27 and -31 engines.
2000hp for take off/2700rpm. Military power 2000hp/2700rpm/1500ft and 1600hp/2500rpm/13500ft.
"Normal" Power. 1600hp/2400rpm/5700ft and 1450hp/2400rpm/13,000ft.

Diameter 52.5 inches.

From the specific engine chart for a -31 as used in a Lockheed Ventura, as found in the manuals section of this website.

take off power 2000hp/2700rpm/52in MAP 5 min limit.
Military power 2000hp/2700rpm/51in MAP 1500ft without RAM and 3500ft with RAM.
....................1600hp/2700rpm/ 47in MAP 12,000ft without RAM and 13,500ft with RAM, 5 min limit.
Max cont........1600hp/2400rpm/41.5in MAP 5300ft without RAM and 7000ft with RAM.
....................1450hp/2400rpm/42.5in MAP 13,200ft without RAM and 14,500ft with RAM 60 min or no limit.
Max Cruise......1100hp/2100rpm/32.5in MAP 10,000ft without RAM and 11,500ft with RAM
.....................975hp/2100rpm/30 in MAP 20,000ft without RAM and 21,000ft with RAM
Some of the RAM figures are in red which means not confirmed by flight test.
Early P-47s had a 5 minute limit on military power, not 15 minutes. So did the early F4Us.

Makes things a bit closer doesn't it.

Now the details come in. The difference between a 52in circle and a 54 in circle is 1.15 sq ft. the FW 190 cowling set the world on it's ear when it came to radial engine cowlings. It is doubtful if a US service cowling would be as good in Jan 1942.
We have been over the fuel, the wing and the armament. Perhaps the US can build a plane that "out performs" the Fw 190 but it won't have any longer range, or a bigger wing or as good as armament. Without the Fw 190 as a goal to aim for would the US restrict themselves to such a small/limited fighter while using their most powerful engine at the start of design in 1939 or 40?
And if you use more fuel, and a bit bigger wing and six .50s with a decent ammo load you wind up with a bigger heavier plane than the Fw 190 with more drag. DO the above power figures show enough advantage to give the American plane better performance?

as for the P-66. See Joe Baugher's page.
Vultee P-66

While the trainers stemmed from work done on the original P-48 fighter project there seems to have been a few trainer parts in the P-48 prototypes. While it may have gotten less credit than it deserves or perhaps the fact that some US users thought it wasn't sturdy enough with the R-1830 engine certainly gives one pause before sticking an R-2800 into it. Basically you need a whole new airplane that just may look a lot like a P-66.

Edit> American propellers may weigh more than the Fw 190 propellers to. I believe the German propellers were wood? Like some British propellers, the same or similar process.

 

[tomo pauk]

Many thanks for the effort of locating typing all the data, the post should be blogged

There is really not much left to add to the data.
One thing remain to be 'subtracted' - that the BMW-801D did have it's power settings (not just the Emergency, but also the Climb combat, as well as Max continous) restricted, both in rpm and MAP. The restriction was in force from March 1942 (= in the time of introduction) until late 1942. So the max power at Emergency (Notleistung) setting was 1320 PS @ 17100 ft; the max rating of 1400 PS @ 18700 ft is 'Blocked for the time being' ('Motorleistung zu Zeit gesperrt'). Please take a look here, at the bottom of the table is the engine data for the 801C -D. The table with engine ratings is attached below, confirming the restriction start date ('ab Marz 1942' only values in the brackets are to be used).*

Now on the drag. I have no problems admitting the 190 have had the neatly streamlined installation of an radial engine. What about the wing? At the pg. 338 of the Vees for victory (per German sources), the wing drag at lift coefficient of 0,2 is stated as 0,0089, vs. P-51s 0,0072 - 25% more. Or, the Cd0 of 0,0269 (per RAE testing, original German data welcomed) - fairly comparable with no-finesses USN fighters (F4F, F4U, F6F). My point is that, even with the top notch cowling, the Fw-190 was offering no advantage vs the R-2800 powered fighters. Other point being that a somewhat greater wing (= greater wetted area), but of thinner profile, would offer about the same drag of the wing as it was the case for the 190. Wing of 250 sq ft would offer the wing loading of 40 lbs/sq ft for an 10000 lbs fighter, while the 200 sq ft wing supporting 8800 lbs (= Fw-190A-5) offers 44 lbs/sq ft - 10% greater wing loading for the Fw-190A, making it less than ideal for high altitudes. Where the thin air makes power- and wing-loading far more of a factor than drag.

*added: I've stumbled upon a date when the restrictions were lifted - 12 Oct 1942. The Wiki article draws that information from the 'Jet prop' magazine of Jan 2010.

 

[davparlr]

Now the details come in. The difference between a 52in circle and a 54 in circle is 1.15 sq ft. the FW 190 cowling set the world on it's ear when it came to radial engine cowlings. It is doubtful if a US service cowling would be as good in Jan 1942.

After some painful research and calculating, I learned that fuselage diameter is only two terms, diameter and swept area (if the diameter of the fuselage increases, the swept area of the fuselage also increases, at least that was my assumption), in Cd0 calculations that also includes wing area, horizontal tail, vertical tail, etc. The source I used, from a site of Daniel Webster University (?), which seems to be a reasonable source, stated that fuselage drag typically made up of about 30% total Cd0. So doing the manipulations they recommended, the impact to Cd0 of the increase in diameter of about two inches is about 1.7% even though the area is actually increased by about 8%. This seems reasonable and does not seem to be a particularly big impact, especially for a 66% increase of hp at SL.
I own up to nothing!

Basically you need a whole new airplane that just may look a lot like a P-66.

Yes.
The aerodynamics of the P-66 seems superior to the contemporary R-1830 powered aircraft, P-36C and the XP-41, it was certainly faster, almost as fast as the P-40, and would out-climb it. However all of these aircraft were basically obsolete and the P-66 was late in this effort. If Vultee had stepped up and made the design to support the R2800, they would have made a jump on the competition, however, I am sure they would not have been compliant with the proposal.

 

[Shortround6]

The whole question of radial engines and drag is up in air. It was a constantly changing area. P&W managed to get a P-40 airframe powered by an R-1830 engine ( I am assuming 2 stage) up to 386mph which is certainly outstanding BUT it took until fall (November I believe) of 1942 to do it. Which basically means summer to fall of 1943 before a production would see service. From the picture it appears the aircraft (basically a test mule) was unarmed.

I can certainly agree with the 1.7% increase in drag, once cowlings showed up in the early 30s the frontal area of the engine was always reduced in effect. However for the 1.7% to be valid both cowls have to be of equal design/efficiency. The difference between a P-36 and a P-40 (early) was 22%. Granted the P-40 was liquid cooled but I am trying to work with the same airframe. The P&W test mule may have achieved it's speed at a higher altitude in thinner air, even so it is faster than a P-40F with a Merlin at 20,000ft.

The question here is were on this curve or path of cowling development would a 1940/41 R-2800 cowling fall? better than the P-36 but not as good as the Fw 190 or P&W experimental cowling ( or later F8F and Fury cowlings)? add the 1.7% to a few percent for not as good a basic design of cowl ( XP-42 went through how many variations and the P-66 itself went through a few) and add in the cooling drag. You are going to need more cubic feet of air going through the cowling to cool an 1850-2000hp engine than a 1600-1700hp one. This is were the big changes in drag for radial engines came from. They had figured out the external shape pretty early. It is the internal airflow/baffling/and exit that changed dramatically. Cowlings like the Fw 190 and F6F and later used the exhaust for two purposes, one was exhaust thrust and the other was to use a flow of air created by the exhaust to suck air through the cowling. The F4U-1 just dumped it's exhaust out the bottom through two pipes.
Granted cowlings can be "tweaked" as a design progresses even through (or especial through) the prototype stages but I have a hard time seeing service cowlings as good as the Fw's in Dec of 1941 or even the Spring of 1942.

BTW, I figure the HP advantage of the R-2800 at 15.6-17.6% at sea level depending on models of engines?

 

[riacrato]

Just giving some food for thought:

An Fw 190 powered by an R-2800 actually exists.

View: https://www.youtube.com/watch?v=XyACmEodRaE

Doesn't look too gross either, it is a tad fatter (the cowling seems slightly "bulged", especially below). Now I'm well aware this is a civilian thing, not designed to military specifications. They mention cooling problems in the comments to the video (for what it's worth). Still shows an Fw 190 sized airframe apparently takes the bigger engine quite fine and doesn't *look* like a drag monster.





I always thought an R-2600 or R-2800 powered Fw 190 or even La-5 type fighter could've been great. The USAAF or USN simply weren't the customer for such fighters (until Kamikazes and the F8F). The only way I see that happening is if for some reasons large quantities of those engines were shipped to the SU who would then probably have used them either for attackers or adapt the Lavochkin to it. But that's unlikely to happen.

 

[tomo pauk]

Two questions, loosely connected to the topic:
- if some kind soul has original German data about Fw-190A's Cd0, it would be neat if it's posted here
-Dr. Tank said that his fighter is the 'Dienstpferd' (service horse), not the Racing horse. He states further that both Spitfire Bf-109 were 'racing horses' - a very large engine on the front of the smallest possible airframe; in each case armament had been added almost as an afterthought. I don't see the Fw-190 being anything but - it was based around the very large engine, that was attached at the smallish airframe, while featuring 4 LMGs as the armament in the 1st iteration. The wing area was at 1st so small that it was upped immediately, even prior the 1st series version; the armament also received prompt increase. So what it was - race or service horse?

 

[Shortround6]

Without knowing a lot more about the engine installation in the Fw it would be hard to draw any real conclusions. We can speculate a lot.

1. Which R-2800 is it? A WW II military engine or a post war Commercial engine? In the 50-60s a lot of F4Us and F6Fs were re-engined with ex airliner engines. Easier to maintain, (more parts around) and few war birds really operate at 20,000ft and above anyway so the lack of a two stage supercharger was no big deal. The late war and post war "C" series engines used different cylinders and cylinder heads than the "A" and "B" engines with more fins or fin area which "should" make them easier to cool at lower power levels.

2. what level of power is this plane using? Full military power? or a lower level of power? this can affect cooling needs. Especially if climate is taken into consideration. Southern California can get pretty hot but as hot as NA or some tropical islands or south east Asia?

3. what modifications were done to the plane? The original Fw used the leading edge of the cowl as the oil cooler. Is this still being done?

I have no answers for any of these questions. Without more knowledge of this particular aircraft any guessing from a short video clip doesn't mean much. One also has to wonder how much more knowledge the builder had from DC-6, Martin airliner and Convair airliner installations to help with this rather than being one of the first 2-3 installations made for the R-2800.

EDIT> BTW, hats off and congratulations for the effort into getting this aircraft built and flying.

 

[davparlr]

BTW, I figure the HP advantage of the R-2800 at 15.6-17.6% at sea level depending on models of engines?

Dummy me, I was comparing it to the R-1830!

 

[tomo pauk]

...
I always thought an R-2600 or R-2800 powered Fw 190 or even La-5 type fighter could've been great. The USAAF or USN simply weren't the customer for such fighters (until Kamikazes and the F8F). The only way I see that happening is if for some reasons large quantities of those engines were shipped to the SU who would then probably have used them either for attackers or adapt the Lavochkin to it. But that's unlikely to happen.

Thanks for the video

While it would be interesting to discuss the La-5 with R-2800 (hopefully the airframe would've coped well with that), I'm more inclined towards the British fighters with that engine. Say, Spitfire with the 1-stager?

*ducks for cover*

added: there is data on the Mike Williams' site that confirms the 12. Oct 1942 as the date when the restrictions for the BMW-801D are lifted.

 

[Shortround6]

Why?

Work it out. Merlin. 45s are available by the time the R-2800-5 is. British don't have time or engineering capacity to even install Merlin XX.

 

[riacrato]

Was that really a problem of time or capacity? I thought that was simply a case of (imo botched) priorities, the engines going to the Hurricane II and other projects instead.