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

[Shortround6]

According to some the Merlin XX was 4in longer and wouldn't fit easily. The Hurricane needed the XX. To stay in the game at all. Spitfire got the MK XII at about the same time. Merlin 45 is pretty much a XII with a XX supercharger without the 2 speed drive. There is only so much engineering time available (that includes draftsmen making the drawings). Wasting it trying to put a low altitude radial on the Spitfire sure seems like a waste of resources.o

 

[riacrato]

Well I'm no expert on th Spit but like I wrote I only ever heard they had that engine planned for the Hurri (like you say it needed it to stay in the game at all), didn't know of any problems to fit them. I personally think, with or without, in late 1940 the Hurri was out of the game as a fighter (imo), and I'd much rather have a 400 mph Spit III to start into '41.

 

[Shortround6]

99% of the time Military aircraft were built to fulfill a need. Not because something would look cool or be fun to fly (although those didn't hurt

It could take Hundreds if not 10s of thousands of hours to engineer an engine "swap" properly and disrupt production for weeks or months. What will the "new" airplane do that the old one won't? Or that the development already in the works won't do?

The Russians went to radials on the LA-5 because the M-105 engine had hit a wall in development and wasn't going much, if any, further.
Pretty much the same story (or worse) with the Japanese, they went to the radial because the 1400-1500hp version of the V-12 turned out to have major problems and then earthquake/bomb damage finished off any hope of getting engines at all, no matter how bad.
Italians went the other way because their production radials had hit walls and the prototypes weren't ready. Too many prototypes with too few engineers.

The Spitfire was working, engine shortages were not in the emergency category or expected to be long lasting> New Merlins were being worked on with the expectation (fulfilled) that they would work. Why spend thousands of man hours on a bodge up job that will be obsolete in months anyway?

 

[tomo pauk]

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.

Why not? Merlin 45 was inadequate to make Spitfire competitive vs. the 109F-4 and even the troublesome Fw-190s (=prior late 1942). The 1-stage R-2800 turns Spitfire into a 1850 HP machine in 1941, 2000 HP machine in 1942. By the time Germans sort out the 801D, the 2 stage Merlin can get into the fray; the radial remaining in production service.
As for the British/Supermarine/RR having no time or engineering capacity to install the XX into Spitfire, that's not the serious statement, right?

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.

Agreed. The power egg from Beaufighter, trialed at that Miles fighter, seem like a neat thing to be attached to the Spit. It also ditches the under wing radiator, not a bright spot on the Spit.

According to some the Merlin XX was 4in longer and wouldn't fit easily.

Yet the 2 stage Merlin could fit? C'mon.

The Hurricane needed the XX. To stay in the game at all.

Too bad that, by that decision, Spitfire V became 2nd, and then, fast, only the 3rd best fighter in ETO.

Spitfire got the MK XII at about the same time. Merlin 45 is pretty much a XII with a XX supercharger without the 2 speed drive. There is only so much engineering time available (that includes draftsmen making the drawings).

Yet it was plenty of engineering time to fiddle with Sabre/Typhoon saga? Granted, not the same companies, but the costumer was the same. The hard pressed Soviets managed to find the time to re-engine the Lagg-3, Italians can do it (3 companies at short time), but the British somehow can't pull it?

Wasting it trying to put a low altitude radial on the Spitfire sure seems like a waste of resources.o

The sentence from above still stands. Making a handful of the Spitfire Mk XIIs seem to imply that there was need to the fighter that can do well under 20000 ft.

 

[wuzak]

Why not? Merlin 45 was inadequate to make Spitfire competitive vs. the 109F-4 and even the troublesome Fw-190s (=prior late 1942).

Was it inadequate compared to the Bf 109F-4? It was inadequate against the Fw 190s.

The 1-stage R-2800 turns Spitfire into a 1850 HP machine in 1941, 2000 HP machine in 1942. By the time Germans sort out the 801D, the 2 stage Merlin can get into the fray; the radial remaining in production service.

The Merlin 45 weighed about 1400lb. The R-2800 about 2300lb. Sure, the Spitfire carried a coolant system and radiator which added to the weight, but it would probably not amount to 1/3 of the difference. Also, all the extra weight would be up front, the Spitfire's coolant system's weight isn't all up front.

The R-2800-5 is 6" longer than the Merlin 45 as well. A lot of re-engineering.

The P-51 was 35" wide at the widest point. I believe that the Spitfire was narrower than that. The cowl on the R-2800 would be 54-55" in diameter.

As for the British/Supermarine/RR having no time or engineering capacity to install the XX into Spitfire, that's not the serious statement, right?

I believe the issue was not enough XXs for both. The Hurricane needed the extra power more.

Remember also that Supermarines were working on the Griffon Spitfire as well - their first proposal for that engine installation was in 1939.

Agreed. The power egg from Beaufighter, trialed at that Miles fighter, seem like a neat thing to be attached to the Spit. It also ditches the under wing radiator, not a bright spot on the Spit.

Aside from making the Spitfire more ugly, you have to ask if it improves the aero any? It certainly has a double whammy effect on weight balance - longer heavier engine up front with a front mounted radiator. It would need some balance weights.

Too bad that, by that decision, Spitfire V became 2nd, and then, fast, only the 3rd best fighter in ETO.

Behind the Fw 190 and P-51A/Mustang I?

Yet it was plenty of engineering time to fiddle with Sabre/Typhoon saga? Granted, not the same companies, but the costumer was the same. The hard pressed Soviets managed to find the time to re-engine the Lagg-3, Italians can do it (3 companies at short time), but the British somehow can't pull it?

The sentence from above still stands. Making a handful of the Spitfire Mk XIIs seem to imply that there was need to the fighter that can do well under 20000 ft.

The problem here is timing. The Griffon Spit was in the works before the Fw 190 appeared. The Merlin 61 was already bench testing when the Fw 190 appeared, and had already been slated for the Spitfire - and probably why the work on installing a Merlin XX was stopped. The R-2800 Spitfire would not, I'm sure, be available before the Spitfire IX (mid 1942) or the XII (late 1942) and wouldn't have the performance of either.

 

[davparlr]

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.

I am not sure this argument comes through in application. The Fw-190A with the 801D engine was capable of doing 330-340 mph at SL with 1700-1800 hp. The contemporary F4U-1, was capable to doing 350 mph at SL with 2000 hp. The F4U is about 2000 lb heavier than the Fw-190 and has 50% more wing area. It seems the the more efficient cowling design, if it existed, helped little to overall aircraft efficiency.

 

[Shortround6]

Why not? Merlin 45 was inadequate to make Spitfire competitive vs. the 109F-4 and even the troublesome Fw-190s (=prior late 1942). The 1-stage R-2800 turns Spitfire into a 1850 HP machine in 1941, 2000 HP machine in 1942. By the time Germans sort out the 801D, the 2 stage Merlin can get into the fray; the radial remaining in production service.
As for the British/Supermarine/RR having no time or engineering capacity to install the XX into Spitfire, that's not the serious statement, right?

You keep keying off the take-off power. The power at combat heights was much different. The Merlin 45 was good for 1230hp at 18,000ft at 12lb boost. What was the R-2800-5 good for at that altitude? Under 1400hp? We are going round and round on the radial engine drag. We know that the P-36 had 22% more than the P-40. even if the FAT-fire has only 14% more drag than a normal Spitfire ( a 1/3 improvement for a even bigger engine) you are down to the power/drag of the Spitfire V. When the British clear the Merlin 45 for 16lb of boost it makes about 1500hp at 11,000ft. A little down from the P&W "A" but then the MK V has a lot less drag. The British aren't really interested in under 10,000ft fighters at the end of 1940 and most of 1941.

I don't know why they couldn't get the XX engine into a Spitfire easily but Edger Brooks keeps saying they couldn't without a lot of rework. Engineering changes and time are not just stuffing one engine into one airframe but designing and building the jigs and fixtures needed to make the parts in an interchangeable manner rather than "filing to fit" which is the cheapest fastest way to build one or two aircraft. A lousy way to build several hundred.

Agreed. The power egg from Beaufighter, trialed at that Miles fighter, seem like a neat thing to be attached to the Spit. It also ditches the under wing radiator, not a bright spot on the Spit.

That "not a bright spot" on the Spitfire may have been one of the "secrets" ( purely unintentional ?) of it's ability to be upgraded. As they added heavier engines in front of the center of gravity the added bigger radiators, oil coolers, and finally inter coolers behind the center of gravity. I am sure it didn't balance out exactly but it sure made things a lot easier than adding ALL the weight on one side of the CG.

Yet it was plenty of engineering time to fiddle with Sabre/Typhoon saga? Granted, not the same companies, but the costumer was the same. The hard pressed Soviets managed to find the time to re-engine the Lagg-3, Italians can do it (3 companies at short time), but the British somehow can't pull it?

Russians, or more properly the Lagg "team" didn't have much choice. Either get the LA-5 going or stop production of the Lagg-3 and start building Yaks.
British were pulling it off, as noted they had been working on alternative engine installations already. How many different engine installations do you want them to work on at the same time?
And it isn't just a question of doing it at all, it is a question of doing it fast enough to actually do some good.
July 1939, sees the Italian air force request the Reggiane company install a DB 601 in a Re.2000. Not to be left out Aeronautica Macchi import a DB 601 engine and started work in Jan 1940, they get a prototype flying in August 1940, (not bad) and as a result of good flight tests is ordered into production. First production example roles out in March 1941, (14-15 months after start) first issue to Squadrons in May-June. 1941. 17-18 Months after start.
When do the British get the bright idea of sticking an R-2800 in a Spitfire to be in service in early 1942? If they can pull it off, what else doesn't get done?

The sentence from above still stands. Making a handful of the Spitfire Mk XIIs seem to imply that there was need to the fighter that can do well under 20000 ft.

There may be a need for a fighter that can do well under 20,000ft. An R-2800 powered Spitfire is not it. By the time you are done you have a new plane. You need the wing tanks from the MK VIII, A rear tank of some sort, different propeller, or late model 4 blade/5 blade several years early and/or new landing gear. You need the bigger tail, you may need to raise the cockpit so the pilot can see over the engine. And so on....

 

[tomo pauk]

Was it inadequate compared to the Bf 109F-4? It was inadequate against the Fw 190s.

When the Notlesitung for the DB-601E was allowed (start of 1942), it was inadequate.

The Merlin 45 weighed about 1400lb. The R-2800 about 2300lb. Sure, the Spitfire carried a coolant system and radiator which added to the weight, but it would probably not amount to 1/3 of the difference. Also, all the extra weight would be up front, the Spitfire's coolant system's weight isn't all up front.
The R-2800-5 is 6" longer than the Merlin 45 as well. A lot of re-engineering.
The P-51 was 35" wide at the widest point. I believe that the Spitfire was narrower than that. The cowl on the R-2800 would be 54-55" in diameter.

Could we say that the engineers would take the challenge with vigor determination?

I believe the issue was not enough XXs for both. The Hurricane needed the extra power more.

Agreed that XXs were not in wide supply, at least not in the 1st year of the production (late 1940 - late 1941). Seem like BC got the lion share of the XXs, not the Hurricane?

Remember also that Supermarines were working on the Griffon Spitfire as well - their first proposal for that engine installation was in 1939.

Agreed.

Aside from making the Spitfire more ugly, you have to ask if it improves the aero any? It certainly has a double whammy effect on weight balance - longer heavier engine up front with a front mounted radiator. It would need some balance weights.

It would also make RAF operating the fighter capable for anything Typhoon can do, say, half a year earlier?

Behind the Fw 190 and P-51A/Mustang I?

IMO both 190 109 were better, in 1942. The P-51 and Typhoon were better under 15-20000 ft, the P-38F becoming a strong contender, too.

The problem here is timing. The Griffon Spit was in the works before the Fw 190 appeared. The Merlin 61 was already bench testing when the Fw 190 appeared, and had already been slated for the Spitfire - and probably why the work on installing a Merlin XX was stopped. The R-2800 Spitfire would not, I'm sure, be available before the Spitfire IX (mid 1942) or the XII (late 1942) and wouldn't have the performance of either.

The timing is the advantage, not the problem. With development work starting early enough, the FAT-fire can have it's R-2800s on board in mid 1941 (assuming, of course, that UK can get those prior the USAAF/USN), and be ready for the arrival of the Fw-190. The performance equal to, again, the Typhoon?

You keep keying off the take-off power. The power at combat heights was much different. The Merlin 45 was good for 1230hp at 18,000ft at 12lb boost. What was the R-2800-5 good for at that altitude? Under 1400hp?

Could you please re-check you numbers? The colored chart I have (and posted it once at the forum) about the Merlins shows 1250 HP at 14000 ft (1050-1100 at 20000 ft), vs. 1500 HP at 14000 ft (1250 at 20000 ft) for the R-2800.

We are going round and round on the radial engine drag. We know that the P-36 had 22% more than the P-40. even if the FAT-fire has only 14% more drag than a normal Spitfire ( a 1/3 improvement for a even bigger engine) you are down to the power/drag of the Spitfire V. When the British clear the Merlin 45 for 16lb of boost it makes about 1500hp at 11,000ft. A little down from the P&W "A" but then the MK V has a lot less drag. The British aren't really interested in under 10,000ft fighters at the end of 1940 and most of 1941.

When British clear the M 45 for the +16 psi boost, the 1942 is on the end (tests being done in late 1942, per WIlliams' site). By that time, the FAT-fire has played it's role, and can soldier on as a preferred under-18000 ft fighter. Saying that a Fatfire is an under-10000 ft fighter is a little too much, more so when comparing with what was historically fielded in the 1st half of the war.

I don't know why they couldn't get the XX engine into a Spitfire easily but Edger Brooks keeps saying they couldn't without a lot of rework. Engineering changes and time are not just stuffing one engine into one airframe but designing and building the jigs and fixtures needed to make the parts in an interchangeable manner rather than "filing to fit" which is the cheapest fastest way to build one or two aircraft. A lousy way to build several hundred.

No point in keying off the perceived inability of the Supermarine to attach the XX at the Spitfire - it was being done in Spit III, and later the 3 different, larger and heavier engines were also installed.

That "not a bright spot" on the Spitfire may have been one of the "secrets" ( purely unintentional ?) of it's ability to be upgraded. As they added heavier engines in front of the center of gravity the added bigger radiators, oil coolers, and finally inter coolers behind the center of gravity. I am sure it didn't balance out exactly but it sure made things a lot easier than adding ALL the weight on one side of the CG.

One thing is location, the other thing is layout. The layout (mounting the radiator box under the boundary layer passage, or installation of the boundary layer splitter) could have been altered, at least once the Bf-109F has being examined. Changing the location serves the same purpose, like what was done from the prototypes of the Typhoon and P-40 towards the serial planes.

Russians, or more properly the Lagg "team" didn't have much choice. Either get the LA-5 going or stop production of the Lagg-3 and start building Yaks.
British were pulling it off, as noted they had been working on alternative engine installations already. How many different engine installations do you want them to work on at the same time?
And it isn't just a question of doing it at all, it is a question of doing it fast enough to actually do some good.

British were pulling it off, the problem was that the fruits of their efforts were rather belatedly installed into the Spitfires - hence the R-2800 to boost the performence, even if that boost is only felt under 15000 ft.

July 1939, sees the Italian air force request the Reggiane company install a DB 601 in a Re.2000. Not to be left out Aeronautica Macchi import a DB 601 engine and started work in Jan 1940, they get a prototype flying in August 1940, (not bad) and as a result of good flight tests is ordered into production. First production example roles out in March 1941, (14-15 months after start) first issue to Squadrons in May-June. 1941. 17-18 Months after start.

Thanks.

When do the British get the bright idea of sticking an R-2800 in a Spitfire to be in service in early 1942? If they can pull it off, what else doesn't get done?

Once they hear about the Typhoon it's projected performance figures?

There may be a need for a fighter that can do well under 20,000ft. An R-2800 powered Spitfire is not it. By the time you are done you have a new plane. You need the wing tanks from the MK VIII, A rear tank of some sort, different propeller, or late model 4 blade/5 blade several years early and/or new landing gear. You need the bigger tail, you may need to raise the cockpit so the pilot can see over the engine. And so on....

I agree that the rework would've involved considerable changes. The gains would be comparable, too.

 

[Vincenzo]

When the Notlesitung for the DB-601E was allowed (start of 1942), it was inadequate.

also before the Spit V is not a good place for fight a Friederich-4.

only the Anton-0 had 4 lmg and were not designed for combat, they were trials planes

 

[tomo pauk]

Thanks for the assessment, Vincenzo. IMO, the performance difference between the F-4 (with 'Notleistung' blocked) and Mk.V was not so big? As to the A-0 being a trial plane, well, putting your gold-worth experienced pilots into a plane that is only partly combat suitable is/was not very wise.

The German take on light planes carrying heavy powerful radials: the Bf-109V-21, or maybe Bf-109X? Pictures can be found easily, this page might be a good start:
Messerschmitt Me 209 II V5

 

[Shortround6]

The German take on light planes carrying heavy powerful radials: the Bf-109V-21, or maybe Bf-109X? Pictures can be found easily, this page might be a good start:

I believe the Bf-109V-21 used a P&W R-1830. Heavy powerful radial ????

 

[Vincenzo]

Thanks for the assessment, Vincenzo. IMO, the performance difference between the F-4 (with 'Notleistung' blocked) and Mk.V was not so big? As to the A-0 being a trial plane, well, putting your gold-worth experienced pilots into a plane that is only partly combat suitable is/was not very wise.

i've not understand if you are joking

the Anton-0 were not used in combat unit

Friederich-4 max speed FTH 391 mph Vs 374 mph no large difference (but the Spit has only 5 minutes power). Just looking for data on climb but i don't find for F-4 i try again tomorrow (i know there is some on this forum)

 

[tomo pauk]

Thanks, I stand corrected.

I believe the Bf-109V-21 used a P&W R-1830. Heavy powerful radial ????

Doh
The 109X was using the BMW-801, though.

 

[johnbr]

They built two of them one with the PW and one with the BMW.

 

[tomo pauk]

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.
...

Hi, SR6, I'd like to return to the data about the 801C.
The Max cruising power, going by the data from the magazine, seems to be higher for the -C than for the -D, and at higher altitude, too. The Emergency power of the 801C is also way out of the chart, more appropriate to the overboosted 801Ds (1,65 ata, from late 1943/ early 1944). I know that you were just typing the available data, but it seem to me that the data from the magazine is dubious, to say at least.
Plus, seem like that Do-217 was never equipped with 801C, but only with -A, -D and -L variants; I'm looking forward to be educated on this, BTW.

 

[Shortround6]

You may very well be right but I am not liking the numbers for "Jane's" either. Look at the Emergency power and climbing power. 400 more RPM and another 0.07 ata is good for 80 more horsepower 600ft higher? It seems that winding the engine up to 2700rpm wasn't good for much?

I think the "MAX Cruise" in the magazine was actually the climbing power though

Not sure how they tested the captured engine.

 

[tomo pauk]

I'd like to get back on this topic, at least to compare what single stage R-2800 was offering. Especially vs. the BMW-801. The more detailed data (about many engines) can be found here.

The chart uses as a basis is for Avenger's engine (R-2600-8, 1700 HP for take off), red are BMWs, blue are single stage R-2800s (A series, as used in early B-26s, and B, as used in later B-26s and war-time A-26s). The A series was produced in 1700+ examples in 1941 (eg. 13 in Jan, 64 in March, 112 in May), the B series follows around Pearl Harbor attack, with 260+ produced in January 1942.

BMW 801C was in use from mid 1941, supplanted in use by Spring of 1942 by 801D. The -D was restricted to 1,32 ata and 2450 rpm until October 1942 (the -C was rated at 1,32 ata and 2700 rpm in low gear, 1,30 ata and 2550 rpm in high gear) - the power in low gear of the -C would be better, with about the same power in high gear, until the -D was cleared for 1,42 ata and 2700 rpm? The -D in graph is for the unrestricted power.

Green square represents the ASh-82, later versions (-F and -FN were able to be over-boosted in lower altitudes). Soviet data gives weight of 780 kg and diameter of 1260 mm (~1720 lbs and 49.6 in), with later versions growing to 900 and 915 kg, respectively. BMW-801 is about 1000+ kg (~2200 lbs), the R-2800 'A' weighting about the same (but of bigger diameter), the 'B' series being about 2300 lbs.

 

[Shortround6]

I think I got us of topic or crossed threads

so I am bringing back to this one from the "different Corsair" thread.

but:

A-20 stays with the R-1830s, so Martin can use the R-2600s?

Cutting engine power by 25% is going to leave you with some rather reduced capability A-20s. And it might not free up the engines you want.

The key things are timing and availability. In 1941 USA can install in it's fighters:

This is quite true and key to the situation.

-V-1710 'C' series engines, either turbo (1150 HP up to 25000 ft), or non-turbo (1040 HP at 13800 ft). Neither -39, nor the engines with 9.6:1 supercharger drive ratio are available (not counting prototypes) before early and late 1942 respectively

Actual not quite right. the -39 was being installed in production aircraft in mid to late 1941. Prototypes had flown in 1940 and orders for hundreds of P-40s with -39 engines had been placed in May of 1940. This is where the "timing and availability" come into play as it could take months if not over a year from the placement of an order to the delivery of the aircraft at the factory with several more weeks/months before the aircraft show up in action.
The Flying Tiger aircraft were sold to China in Jan 1941, arrived in Rangoon, Burma in June of 1941 and went into action Dec 20th 1941 as a somewhat extreme example.
As of Dec 1 1941 there were 74 P-40Es in the Philippines.
The First Allison with 9.60 gears was the F6R in 1940 but it didn't get very far, second ( 3rd) were the F14 and E12 of which 54 were built in late 1941 but these are the ones that had trouble with the supercharger gears and had to be rebuilt with 8.80 gears while a new gear housing and gears were worked on for the later F20R engine. We have difference between what was planed and what was deliverable.

-R-1830, single stage or turbo

No argument.

-R-2800 single stage, 'A' series

Only if you kill the B-26

-Wright engines (R-1820 and R-2600)

R-1820 is available but a bad choice. The R-2600 is available in numbers but that is the 1600hp "A" engine as used in the A-20 and some other aircraft. about 443 of the 1700hp "B" series were built in 1941 (206 in Dec), this is the engine used in the B-25 and it was built in a different factory (except for 147 built in 1942) than the "A" series engine and used a steel crankcase instead of aluminium among other changes.

Trying for the early R-2800 powered fighter (single stage) without redoing the production schedules of the engines calls for lower powered A-20s, lower powered B-25s and lower powered B-26s ( if any B-26s at all)

Comparing a R-2800 from Jan 1941 with V-1710 from late 1942 (full throttle at 15500 ft) is funny, to say at least.

Not so funny, Allison was not only promising the 9.60 gears for Nov/Dec of 1941 they were building small runs of engines and running model/type tests. The supercharger gears failed. Other improvements (like nitrided crankshafts) were incorporated in production engines of other models.

IF in the summer of 1941 Allison is promising 1125hp at 15,500ft (having first proposed such an engine in 1940) and P&W has built NO "B" seies engines and only 500-600 "A" series engines (let alone actual installed them in aircraft) AND you expect Packard Merlins to start showing up in Dec/Jan (engines were ordered in Sept of 1940) WHEN do you design/work on the R-2800 powered fighter? USAAC had ordered over 700 P-47s with turbo R-2800s in the fall of 1940.

The timing and availability of the engines does not come out in favor of a "simple, single stage" R-2800 powered fighter. Another thread talks about America having too many types of aircraft. This is a case of trying to design a specialized aircraft to be produced for a very limited amount of time until it is obsolete.

 

[tomo pauk]

I think I got us of topic or crossed threads

so I am bringing back to this one from the "different Corsair" thread.
but:
Cutting engine power by 25% is going to leave you with some rather reduced capability A-20s. And it might not free up the engines you want.

The B-26 looks like a better way to use R-2600s than A-20, even if they make only 1600 HP at take off.
The Douglas Havoc I was good for 462 mi, with 325 gals and 2080 lbs of bombs; the A-20A was good for 525 mi with 388 gals and 2400 lbs of bombs. So we loose 10% of range, unless 'my' A-20 minus' is outfitted with 350-360 gals?

Actual not quite right. the -39 was being installed in production aircraft in mid to late 1941. Prototypes had flown in 1940 and orders for hundreds of P-40s with -39 engines had been placed in May of 1940. This is where the "timing and availability" come into play as it could take months if not over a year from the placement of an order to the delivery of the aircraft at the factory with several more weeks/months before the aircraft show up in action.

Agreed, you are right here.
My addition - the -39 engine does not offer anything in performance over the A series R-2800, at any altitude - the A has 40% more power above 14000 ft.

The Flying Tiger aircraft were sold to China in Jan 1941, arrived in Rangoon, Burma in June of 1941 and went into action Dec 20th 1941 as a somewhat extreme example.

Yep, they gave a good account with 'sharp nosed' Curtiss.

As of Dec 1 1941 there were 74 P-40Es in the Philippines.

+1

The First Allison with 9.60 gears was the F6R in 1940 but it didn't get very far, second ( 3rd) were the F14 and E12 of which 54 were built in late 1941 but these are the ones that had trouble with the supercharger gears and had to be rebuilt with 8.80 gears while a new gear housing and gears were worked on for the later F20R engine. We have difference between what was planed and what was deliverable.

Again, fine points.
The appeal of the R-2800 is/was that it was actually available, while powerful and reliable.

Only if you kill the B-26.

Indeed. We might, however, actually build (X)B-28 (even without turbo), once the R-2800 production hits the stride

R-1820 is available but a bad choice. The R-2600 is available in numbers but that is the 1600hp "A" engine as used in the A-20 and some other aircraft. about 443 of the 1700hp "B" series were built in 1941 (206 in Dec), this is the engine used in the B-25 and it was built in a different factory (except for 147 built in 1942) than the "A" series engine and used a steel crankcase instead of aluminium among other changes.

Agreed. The Wright engines are not the 1st choice for fighters, I've just stated them for completeness sake.

Trying for the early R-2800 powered fighter (single stage) without redoing the production schedules of the engines calls for lower powered A-20s, lower powered B-25s and lower powered B-26s ( if any B-26s at all).

It also calls for an early US-built fighter that can actually clash with Axis fighters while not suffering too big a performance advantage (while outperforming Japanese fighters, and able to actually climb to kill Japanese 2-engined bombers), that would be available for the Allies from summer of 1941. It calls for a carrier-borne fighter that will do it's task, even if the unexperienced controller puts it 3000 ft under the incoming bomb run, somewhere in South Pacific in 1942.

Not so funny, Allison was not only promising the 9.60 gears for Nov/Dec of 1941 they were building small runs of engines and running model/type tests. The supercharger gears failed. Other improvements (like nitrided crankshafts) were incorporated in production engines of other models.

IF in the summer of 1941 Allison is promising 1125hp at 15,500ft (having first proposed such an engine in 1940) and P&W has built NO "B" seies engines and only 500-600 "A" series engines (let alone actual installed them in aircraft) AND you expect Packard Merlins to start showing up in Dec/Jan (engines were ordered in Sept of 1940) WHEN do you design/work on the R-2800 powered fighter? USAAC had ordered over 700 P-47s with turbo R-2800s in the fall of 1940.

In other words, Allison has only prototypes of the '9.60' engines to promise/show, before mid 1942. In the defense of Allison, the are overtaxed with many versions of their engine, many things will be abandoned or get late.
As for when we should order the fighters - on Feb 1st 1938, the USN holds a design competition for a new fighter, to what Vought proposes a fighter with R-2800 in April 1938. The US Army issued 'Circular Proposal 39-640' in March 1939, to what Martin responded with future B-26. So, the design of the new fighter might commence in 1938.

The timing and availability of the engines does not come out in favor of a "simple, single stage" R-2800 powered fighter.

Here we disagree.

Another thread talks about America having too many types of aircraft. This is a case of trying to design a specialized aircraft to be produced for a very limited amount of time until it is obsolete.

Not a specialized aircraft, neither of a limited time of usability.
For example, Grumman might decide that there is no much point in developing a fighter that would be only slightly better than F2A, and go for the new P&W engine to power their new fighter. Six HMGs, 200-220 gals, 250-280 sq ft wing. If they keep the wing thickness at 15% (root), it can replace F4F, F6F, F8F (once the 'C' series arrives). Nobody talks about Airabonita anymore, P-60, P-66. The new fighter can be a bomber comparable with Fw-190, F6F and F4U.
In RAF, CW and VVS use it can offer much more than P-39/40 and F4F.

 

[Shortround6]

The B-26 looks like a better way to use R-2600s than A-20, even if they make only 1600 HP at take off.
The Douglas Havoc I was good for 462 mi, with 325 gals and 2080 lbs of bombs; the A-20A was good for 525 mi with 388 gals and 2400 lbs of bombs. So we loose 10% of range, unless 'my' A-20 minus' is outfitted with 350-360 gals?

The DB-7 had weights of 11,400 pounds empty, 17,031 pounds maximum take-off. top speed 305 mph at 9650 feet with a single speed R-1830, some improvement with better R-1830s could be anticipated.

Early A-20s had weights of 15,165 pounds empty, 19,750 pounds gross, 20,711 pounds maximum. but the upper weights went to 21,000 pounds gross, 24,500 pounds maximum with the A-20C in early 1941 and late war versions were allowed up to 30,000lb max overload. Top speed went to 340-350mph on the early ones.

Agreed, you are right here.
My addition - the -39 engine does not offer anything in performance over the A series R-2800, at any altitude - the A has 40% more power above 14000 ft.

You are right, it certainly doesn't offer anything in performance over the A series R-2800 but the A series R-2800 weighs about 700lbs MORE than a -39 WITH radiator and coolant (and NOT counting the heavier propeller) and if a R-1830 has 22% more drag what does a R-2800 have for drag? The Allison is much easier to get exhaust thrust from ( early F4Us don't appear to use much exhaust thrust) and you need more fuel for the R-2800. An single stage R-2800 "B" can burn 3.5 gallons a minute in Military power at 12,000ft (47") and 4.5 GPM at 2000ft (52") The Allison burns about 2/3rds. Cruise burns are closer.

A fair amount of the 40% more power is used up in lugging the R-2800 and it's fuel around (fuel system for a F6F's 250gals weighs about 460lbs) and overcoming drag.

The R-2800 powered plane will perform better, just don't expect anywhere near even 20% better.

Yep, they gave a good account with 'sharp nosed' Curtiss.

AS I said, an extreme example but it was almost one year for placement of order for a plane "already in production" AND 'waived' deliveries before they saw action, speaks to "timing and availability"

It also calls for an early US-built fighter that can actually clash with Axis fighters while not suffering too big a performance advantage (while outperforming Japanese fighters, and able to actually climb to kill Japanese 2-engined bombers), that would be available for the Allies from summer of 1941. It calls for a carrier-borne fighter that will do it's task, even if the unexperienced controller puts it 3000 ft under the incoming bomb run, somewhere in South Pacific in 1942.

I know what the 'idea' is. In the summer of 1941 P &W was turning out around 100 "A" series engines a month, Allison was building 400-600 engines a month. Things were changing rapidly. January 1941 production was 13 to 130 and in Dec 1941 it was 525 to 1100 but Ford had produced 162 of the R-2800s.

four .50 cal guns might do for the Japanese 2-engined bombers IF the fighter can get in position and IF the guns actually work. Please plug the two stage R-1830 into the chart, 1000hp at 19,000ft. and note that the single stage R-1830 is about 600-700 lighter, smaller in diameter and uses a smaller propeller and less fuel.

In other words, Allison has only prototypes of the '9.60' engines to promise/show, before mid 1942. In the defense of Allison, the are overtaxed with many versions of their engine, many things will be abandoned or get late.
As for when we should order the fighters - on Feb 1st 1938, the USN holds a design competition for a new fighter, to what Vought proposes a fighter with R-2800 in April 1938. The US Army issued 'Circular Proposal 39-640' in March 1939, to what Martin responded with future B-26. So, the design of the new fighter might commence in 1938.

It might, in fact it would almost have to start design work in 1938/39 to be in production in 1941. Problem is that the US is NOT in a shooting war and the "simple" R-2800 fighter doesn't offer what the either the Navy or the Air Corp want. They both want the altitude performance that a 2 stage supercharger brings. The Air Corp wants turbos but knows it can't get them. It 'settles' on the P-39 and P-40 as interim fighters that can be produced in quantity while the next generation of fighters is worked on. The Navy is sliding from the F2A to the F4F and wants the altitude performance the two stage mechanical supercharger "promises", flying examples still aren't working quite right. Buying a successor to the F4F that goes a step backward in altitude performance is probably not going to happen.

Please remember that at this time NOBODY even knows what 100/130 fuel is. They do know what 100/100 fuel is. Promised power outputs 2-4 years ( or 6-7 years for the F8F) down the road have to be looked at with this in mind. They might expect better fuel to become available but since they don't know how to make yet the when is really up in the air.

Not a specialized aircraft, neither of a limited time of usability.
For example, Grumman might decide that there is no much point in developing a fighter that would be only slightly better than F2A, and go for the new P&W engine to power their new fighter. Six HMGs, 200-220 gals, 250-280 sq ft wing. If they keep the wing thickness at 15% (root), it can replace F4F, F6F, F8F (once the 'C' series arrives).

Slight problem in timing here, Grumman built 106 F4Fs in 1940 when only 17 R-2800s were built. Grumman also has hands full designing and building the first TBF. Grumman has a slight problem turning out F4Fs in 1941 too, compounded by P &W inability to deliver two stage engines.



The F8F is a pipe dream at this point. It needs the "C" series engine which is a totally new engine that just kept the same bore and stroke (1700hp at 16,000ft for the F8F-1), it needs the new supercharger, it needs less fuel and less armament than you are proposing to get it's performance. Try building a 9600lb (gross weight of clean F8F-1) plane in 1940-41 and selling it to the Navy with a 1850hp engine instead of 2100hp for take off and with 50% MORE weight of armament AND 25% more fuel than the 9600lb F8F AND the F8F did NOT meet the NAVY specs for structural strength in place in 1940-41.

A 1940-41 "F8F" will be heavier and have less power and more drag ( a 1940-41 radial installation NOT at 1943-45 installation) than the 1945 F8F.

The Navy and Air Corp will STILL WANT the two stage planes for 1943 ( production starting in mid 1942) for performance the single stage engine cannot offer. By mid to late 1942 EVERY 'simple' R-2800 powered fighter built is a P-47 or F4U or F6F NOT built. Hopefully the hundreds or couple of thousand "simple" fighters bought enough of advantage in 1942 that the change over or continued use of the poorer performing "simple" fighters doesn't cause any problems.