# 1941: the best case for 350+ mph CV fighters?



## tomo pauk (Feb 8, 2017)

...CV meaning 'carrier vessel'.
Basically - how would've looked a speedy carrier-borne fighter for each country with CVs, whether the carriers are in service or in pipeline. Best case, but still plausible (no non-historical engines or arodynamic properties), with acceptable low-speed characteristics, plus the weapon and protection suite as used on the fighters of respective air services/forces in 1941. With useful range/radius.


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## parsifal (Feb 8, 2017)

Well, the elephant in the room are the German and British conversions that coulda and shoulda, but never eventuated (well not quite true, the Me109T, the conversion of the E-3 was completed, but never flew from a carrier, the me 109f was only ever projected, whilst the seafire did happen and was used from a carrier but arrived vary late for the party). I am referring to the Me-109T and Me 109F conversions (mooted) for the failed KM carrier. For the British the missing thoroughbred was the seafire II, which the admiralty had wanted since at least 1939, but consistently rejected by an indifferent, even hostile air ministry.


The seafire needed some work, undoubtedly, but none of it was technically infeasible. The chief changes required were wing folding, strengthened landing gear, redesigned and widened landing gear as opposed to the narrow tracked types accepted for the land based version.


It would take until the Seafire III series before anything like a decent navalised version of the Spitfire was produced. It could have happened years before it did

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## pinehilljoe (Feb 8, 2017)

The Corsair? If funds were available at Wartime levels, could the development have matured and production started to deploy it to the Fleet before the end of 1941. The first flight was May 1940.


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## parsifal (Feb 8, 2017)

Possibly. Additional funding would not have gone astray, but there were problems with the earliest prototypes revealed seriously weak main armament, CG issues and serious spin recovery issues. These were well on the way to being solved by June 1941, but delays in setting up production lines meant the type did not begin to enter squadron service until June 1942. It was literally years later before the USN accepted them for carrier service because of its limited vision characteristics and somewhat unsatisfactory handling capabilities.


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## GrauGeist (Feb 9, 2017)

There was a P-51 (P-51-NA), s/n 41-37426 (BuNo. A57897) that was evaluated by the USN long before they considered the P-51D.

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## wuzak (Feb 9, 2017)

GrauGeist said:


> There was a P-51 (P-51-NA), s/n 41-37426 (BuNo. A57897) that was evaluated by the USN long before they considered the P-51D.
> 
> View attachment 365171



First flight was in October 1940, so I doubt a navalised version would be available before the end of 1941.

Even converting the P-40 would have been a stretch for 1941.


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## GrauGeist (Feb 9, 2017)

The USN had considered the P-36 for potential naval service, but not the P-40.

On the otherhand, they did consider and evaluate a P-39 (XFL-1).

The XFL-1 was a response to the USN's 1938 request for a replacement for the current aircraft in service - it may be of interest that of the companies that responded (Bell, Brewster, Curtiss, Grumman, Vought) only three contracts were awarded: Bell (XFL-1), Grumman (XF5F) and Vought (XF4U). All three prototypes first flew in 1940 and all three were over the 350 mph mark.

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## tomo pauk (Feb 9, 2017)

For the Italians - a combo between MC.202 and Re.2001? Japanese - something with Kinsei, or Kasei, or Ha-41?


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## Shortround6 (Feb 10, 2017)

Pretty much it is the Seafire/109 or nothing. 

Throw in the "With useful range/radius." and even the Seafire/109 looks dubious. 

The XFL-1 wasn't fast enough, had handling problems and needed work on the landing gear. 

The delay in the Corsair was NOT due to lack of funds. Roosevelt had called for a 50,000 plane air force in the summer of 1940. The US was spending scores of millions on new factories in 1940. The Corsair needed hundreds of revisions AND the Navy had to rethink and abandon several of their acceptance tests for aircraft (like the 10 turn spin and recovery to both left and right and the terminal velocity dive).

Because a plane was _evaluated _for carrier use doesn't mean it was suitable. That is what the evaluation is for. Now standards do change and what was acceptable in 1943/44 was NOT acceptable in 1940/41. 

For the Italians you have a problem, the MC.202 has a wing that is too small (and not enough fuel?) and Re.2001 which is too slow. 
Try to cross them and ?????

The Japanese are behind the curve on engine power, the Kinsei, or Kasei, or Ha-41 engines of 1941 are hundreds of HP down on power compared to the versions available in 1943 and later. 

It looks like, for liquid cooled engines 1150-1200hp is not enough to get the job done, you need more power. And for air cooled engines the need for even more power really limits the available engines.


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## GrauGeist (Feb 10, 2017)

I tossed in those historical types considered by the USN, because they were pretty much it, as far as potential candidates for Tomo's criteria.

What it boils down to, is that the U.S. really didn't have a better candidate by 1941, than the F4F-3. It's performance profile was better than the P-36A both in range and speed (and basic firepower layout) and it wouldn't be until the F4U worked out it's bugs and the introduction of the F6F, that the USN would have a truly potent fighter.

Even the P-51-NA would have had it's shortcomings if it had been adopted by the USN early on, and would not be ready for fleetwide service by 1941 in any case.


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## tomo pauk (Feb 10, 2017)

Shortround6 said:


> Pretty much it is the Seafire/109 or nothing.
> 
> Throw in the "With useful range/radius." and even the Seafire/109 looks dubious.
> It looks like, for liquid cooled engines 1150-1200hp is not enough to get the job done, you need more power. And for air cooled engines the need for even more power really limits the available engines.



The British have the Merlin XX and 45, Germans have the DB 601N and 601E, so those should do the trick.



> For the Italians you have a problem, the MC.202 has a wing that is too small (and not enough fuel?) and Re.2001 which is too slow.
> Try to cross them and ?????



The wing area of the MC 202 was some 180 sq ft, the Re.2001 was at ~220 sq ft - so yes, something with perhaps 200 sq ft wing?



> The Japanese are behind the curve on engine power, the Kinsei, or Kasei, or Ha-41 engines of 1941 are hundreds of HP down on power compared to the versions available in 1943 and later.



Ha-41 was with same ~1250 HP at 12100 ft in 1943 as it was in 1941; 1185 HP for take off.
The Ha-101 (Army nomencalture; member of Kasei family; installed on Sally bomber from early/mid 1940 on) was making 1360 HP at 13100 ft, and 1490 HP for take off.
Kinsei 46, installed on Mavis flying boat - 1055 HP at 13800 ft; 985 HP for take off.

For comparison - Sakae 12 (installed on early Zeroes) was with 935 HP at 13800 ft; 925 HP for take off. Pushed the Zeroes to 330 mph at best altitude.


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## Elmas (Feb 10, 2017)

I would have say RE 2000: first flight mid 1939, wing tanks and very good autonomy for the period, some flying caracteristics to iron out but quite acceptable, but with just 1000 HP and 286 kts, certainly not exactly a greyhound.


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## pinsog (Feb 10, 2017)

There were only a bare handful of 350 mph land based fighters in 1941. Lets count Spitfire, ME109 in service in numbers. The P38, P39 and P40 I don't think started being delivered until mid 1941 and even then, I think are all just in very small handfuls. 
The P43 Lancer is about the only real 350 mph fighter the US could have had available in some quantity in 1941 and even though no other US fighter could compete with it above 20,000 feet, until the P38, we ironically, decided to not build but a few of them and not use them at all.(I'll concede that before the P43 was deployed to squadrons, they should at least have ditched the wet wing and used proper fuel tanks that didn't leak, self sealing would be even better)

Spitfires tended to fall apart after a few days of combat aboard a carrier. I wouldn't think an ME109 would be much of a carrier aircraft either, I mean by the time you took off from the carrier and got it up to 350 mph you would barely have enough fuel to get back and land.

I don't see any real hope for a 350 mph true carrier based fighter unless the US had developed the XF5F instead of the F4F-3 and even then I think it would have been later than your 1941 timeline unless some other priorities had been shifted around


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## tomo pauk (Feb 10, 2017)

pinsog said:


> I wouldn't think an ME109 would be much of a carrier aircraft either, I mean by the time you took off from the carrier and got it up to 350 mph you would barely have enough fuel to get back and land.



The Bf 109 with a drop tank is a rangy bird, even if it is no Zero or P-51. The 109G with DT was with range (not radius) of 1000 miles, or 616 without it.



> I don't see any real hope for a 350 mph true carrier based fighter unless the US had developed the XF5F instead of the F4F-3 and even then I think it would have been later than your 1941 timeline unless some other priorities had been shifted around



Grumman, when they lost (June 1938) the initial competition vs. the future Buffalo, decides to shelve the fighter that is designed with R-1830 in mind, and go for the whole hog, namely to ask P&W the specifics for their newest baby, the (X)R-2800, in order to design a fighter around it. Mock-up made by early 1939, prototype flown in early 1940, the serial production starts by early 1941?

If that is too aggresive, proposal #2: Grumman sees the loosing proposal as too big for the Twin Wasp, decides to cut the dimensions of fuselage & wings (wing area of 210 sq ft instead of 260 sq ft as in F4F-3/4), installs the fancy new Fowler flaps in order to keep low-speed handling acceptable. The 'Smallcat' makes 330 HP with 1-stage Twin Wasp, 350 mph with 2-stage Twin Wasp.


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## pinsog (Feb 10, 2017)

Here is a "what if". What if the R2800 had been a failure like several of the British engines and some of the American engines? Then you don't have a Hellcat in mid 1943, or a Corsair.

The Skyrocket and the Hellcat have the same top speed at sea level 312. At 17,000 feet, the Skyrocket is doing 357 on LESS hp than the Hellcat. At 17,000 the Hellcat is doing 357 on 1825 hp Military power while the Skyrocket is doing 357 on less than that because the Wright 1820-G231 were only rated 900 a piece up to 14,000 feet. So if the Skyrocket would do 357 on less than 1,800 hp, what would top speed be with 2,400 total hp (turbocharged 1820's) at that altitude? What would top speed be at 25,000 feet with 2,400 hp?

They could have had F6F performance with current, proven engines in 1941 with the Skyrocket and should have been able to substantially exceed Hellcat performance if they had installed the turbocharged Wright 1820. Im sure performance would have gone up even more if they had chosen P&W 1830's instead of the Wright 1820 because of less drag, the Wildcat and P36 were both better with the P&W.


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## parsifal (Feb 10, 2017)

Seafire III were the most reliable in the BPF, in 45 after the major shortcomings of the Seafire II were rectified. If a little mud sticks early on its hard to get off your boots . Range (effective combat radius) of the late war SeafireIII was s just under 200 miles. F6Fs with the BPF were about 220 miles, and Corsairs about 240miles.. There was bugger all difference in the range of the three types if you want to look at typical mission profiles.. The shortcoming of the seafire was that it lacked effective multi role capability, which the Lend lease fighters possessed. They were far superior down low and packed about twice as much firepower 

Me109T was intended to carry a large capacity centreline droptank as standard. I don't know its effective combat range, but it would be considerably more than your stock LB 109

The narrow track LG of both the 109 and the seafire were about the same as the F4F. That wasn't the issue with Seafires early on, they had a weakness in one of the support struts that was easily rectified. All liquid cooled a/c have a real vision problem, but not insurmountable


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## Shortround6 (Feb 10, 2017)

It was not just the aircraft but the carriers and operating doctrine. It is no great trick to catapult small fighters into the air with drop tanks but range is not based on individual aircraft but the range of the group. First planes up have to orbit until the last planes are up. If the carrier only has two catapult s how long does it take to get the group in the air? The US planned on flying off, not catapult for a higher launch rate. 
You are also back to operational radius depending on internal fuel for fighting, cruise home and a bigger reserve than land operations, you only have one landing "area" (task group) with a limited number of runways. You have to find it and then have enough fuel for ALL planes to land (including time out for several bad landings). 
What is the *range *of the 109 with 10-15 minutes of combat and 30 minutes or more of reserves for finding the carrier and queuing up to land taken away from the internal fuel?

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## tomo pauk (Feb 10, 2017)

Nobody pretends that radius (it is no more 'range' when we talk about the fuel consumed in combat, plus the obvoius thing as return from combat) will be Zero-like with a drop-tank outfitted sea-going 109. But then the range/radius should be similar with Seafire that has a 90 gal DT, or Sea Hurricane with two 45 gal DTs. On some tests of the 109G-2, range figure with DT is mentioned as 1250 miles, endurance of 6 hours (link).


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## pinsog (Feb 10, 2017)

How do you guys think an ME109 would handle controlled crash landings on a carrier day after day?(Spitfire didn't like it)
How well would that tiny little fighter handle the weight gain of being navalized?


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## tomo pauk (Feb 10, 2017)

The light & small A5M Claude was conceived without requirement for carrier operations, and went to be unproblematic CV fighter. Light base weight means that modifications and reinforcements can also be lighter.


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## Shortround6 (Feb 10, 2017)

Hmmmm, A5M4 was in a whole different class than the 109. A wing a speckle bigger than wing on a 109T and weight of around 62% (both clean) means a much lower stalling speed. Wing loading of a 109T was 32.7lb per sq fr clean. the A5M4 was under 20. Even a late model F4F-4 was under 31 lb/sqft clean. 

Some things are scaled due to the size/weight of the fighter and somethings are not. A small plane needs a proportionally larger hook on the arresting gear because the cables are a standard size and standard height above deck. Catapult attachment points are standardized. Yes the reinforcement on a lighter plane _might _ be lighter. 

as for the controlled crashes. The main landing gear on a P-40 had 7in of travel. the P-51 had 8in, the F4F had 12.5in of travel. 
Other planes had????

Different countries may have had different radius requirements due to the size of the carriers and doctrine. The US operate large carriers with large strike groups.(or multiple carriers per carrier task force) As did the Japanese. the majority of early war British carriers, the only French carrier, the planned Italian carrier and the German carrier/s (planned/converted) operated small air groups and didn't have to speed as much time forming up or recovering strike groups. Of course some of these carriers would only have a nominal effect on a battle. For the Germans it doesn't matter if the carrier fighters do 330mph or 360mph. With only 12 fighters planned to be embarked they hardly have enough for a CAP let alone an escort group for the strike planes. 
The Spitfire/ 109 Hurricane and any like conversions may have enough range/endurance for use in European waters but would be short of range/endurance for pacific operations.


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## pinsog (Feb 10, 2017)

Back to my point: The only LAND based planes of the time that could legit do 350 mph were the Spitfire and ME109
No Japanese fighters could. Only US fighter that was 350 capable and in service in any numbers by 1940 was maybe P40? P38 wasn't, P39 wasn't and P43 wasn't even going to be produced


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## GrauGeist (Feb 11, 2017)

The P-43 had a max. speed of 356 and while that may seem impressive, it's 650 mile range becomes a liability.


pinsog said:


> How do you guys think an ME109 would handle controlled crash landings on a carrier day after day?(Spitfire didn't like it)
> How well would that tiny little fighter handle the weight gain of being navalized?


The Bf109's gear was actually designed to handle unimproved (grass) operations, this attribute would certainly mean it was rugged enough for carrier ops.

And the P-43 was produced: 272 units built and put into service in various capacities.


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## tomo pauk (Feb 11, 2017)

pinsog said:


> Back to my point: The only LAND based planes of the time that could legit do 350 mph were the Spitfire and ME109
> No Japanese fighters could. Only US fighter that was 350 capable and in service in any numbers by 1940 was maybe P40? P38 wasn't, P39 wasn't and P43 wasn't even going to be produced



The thing with Japanese is that engine chosen to power production Zeroes was perhaps 5th power-wise choice. For 1941, stick the Ha-41 on Zero and engine power goes up by 1/3rd.



GrauGeist said:


> The P-43 had a max. speed of 356 and while that may seem impressive, it's 650 mile range becomes a liability.
> ...



The P-43 seem to make 1000 miles on 145 gals and 227 mph. Max fuel (no drop tank yet) was 218 gals.
http://www.wwiiaircraftperformance.org/P-43/P-43_Official_Summary_of_Characteristics.jpg
http://www.wwiiaircraftperformance.org/P-43/P-43_Official_Performance_Summary.jpg


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## Shortround6 (Feb 11, 2017)

You have different loads between carrier operations and even grass fields.
Carrier landings usually involve higher sink rates or higher vertical impact speeds. 
Once "down" or on take off the surface is much smoother. 
There is also a world of difference between a prepared grass or dirt field and an "unimproved" one. Think of hitting speed bumps at 50-70 mph. There is not only a vertical movement but a rearward twist/load. 
Spitfires were designed to operate from grass fields but they were hardly "unimproved".

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## tomo pauk (Feb 11, 2017)

pinsog said:


> Here is a "what if". What if the R2800 had been a failure like several of the British engines and some of the American engines? Then you don't have a Hellcat in mid 1943, or a Corsair.



We do have the Hellcat, it would've been powered by 2-stage R-2600, just like it's 1st prototype. Probably good for 360+ mph in 1943.



> The Skyrocket and the Hellcat have the same top speed at sea level 312. At 17,000 feet, the Skyrocket is doing 357 on LESS hp than the Hellcat. At 17,000 the Hellcat is doing 357 on 1825 hp Military power while the Skyrocket is doing 357 on less than that because the Wright 1820-G231 were only rated 900 a piece up to 14,000 feet. So if the Skyrocket would do 357 on less than 1,800 hp, what would top speed be with 2,400 total hp (turbocharged 1820's) at that altitude? What would top speed be at 25,000 feet with 2,400 hp?



Truth to be told, the Hellcat was fully armed and protected when doing that turn of speed, unlike the XF5F. The Skyrocket will need to go for Twin Wasp (more power, smaler frontal area) in order to reclaim speed lost once armament & protection is installed.
The 'turbo Skyrocket' with 2400 HP will probably see 380 mph with radials?



> They could have had F6F performance with current, proven engines in 1941 with the Skyrocket and should have been able to substantially exceed Hellcat performance if they had installed the turbocharged Wright 1820. Im sure performance would have gone up even more if they had chosen P&W 1830's instead of the Wright 1820 because of less drag, the Wildcat and P36 were both better with the P&W.



This can help us compare the sizes of nacelles required for the F5F with Twin Wasp vs. with Cyclone (just 2 wievs, not 5):







The engine power goes up by 100 HP pre engine in 1941.


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## pinsog (Feb 11, 2017)

GrauGeist said:


> The P-43 had a max. speed of 356 and while that may seem impressive, it's 650 mile range becomes a liability.
> 
> The Bf109's gear was actually designed to handle unimproved (grass) operations, this attribute would certainly mean it was rugged enough for carrier ops.
> 
> And the P-43 was produced: 272 units built and put into service in various capacities.



I knew they made 272 P43's, but we didn't use them as a fighter. (Chinese did)
No way was I suggesting the P43 be used on a carrier. P43 would never have worked on a carrier. I DO think it should have been produced in some quantity (with a redesigned wing that had fuel tanks, not a wet wing) as a stop gap fighter in the Pacific until the P38 arrived in numbers. 

My point, and I didn't type enough detail, was that there were only MAYBE half a dozen 350 mph LAND BASED fighters in the world at the beginning of 1941 and only 2 (Spit, 109) were even in mass production. SO the possibility of a carrier based 350 mph fighter was virtually 0.

Again, I think the only real possibility of a 350 mph carrier based fighter at the beginning of 1941 would be the XF5F and that is only if Grumman had completely dropped the Wildcat and only focused on the Skyrocket. Maybe the Skyrocket would have been a total failure, maybe it would have been a game changer from December 1941-June 1943 (or when ever the Hellcat finally showed up). I think it would have, with P&W 1830's, given Hellcat performance 1 1/2 years earlier, but we will never know.


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## Shortround6 (Feb 11, 2017)

Thank you for the pictures. The smaller nacelle _may _be for the Twin Wasp _*Junior * _* R - 1535 *and not the Twin Wasp R-1830.
The F5F was conceived around the R-1535. 
The pictures do drive home the point that a pair of R-1820 Cyclones need a fair amount of power to drive through the air.


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## pinsog (Feb 11, 2017)

No doubt they should have been using the P&W 1830's instead.


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## Conslaw (Feb 11, 2017)

If the goal would be to have a 350-mph fighter on carrier decks du 1941,IMHO the best bet would have been to rush out a production version of the XF4U without making the changes they actually made. Of course this wouldn't have been a very good aircraft, and it would have been an even worse carrier aircraft, but it would have been at least as good as its competitors, the navalized Airocobra and the F5F, because those aircraft would have had uncorrected problems of similar or greater magnitude if rushed into service in
A short note about the P-43: The P-43 had roughly a 20-MPH speed advantage over the F4F.-3 with the same engine. This difference is in line with the difference in speed between the Spitfire and the Seafire, and it is roughly equal to the difference in speed between contemporary F4Us and P-47s. A navalized P-43 would have been no faster than the F4F-3.

The F4F-3 was a state-of-the-art carrier fighter in 1941. The A6M Zero was too. The designers of both aircraft just made different choices. The two-staged supercharger on the F4F-3 was an advanced technology of the time, and the Navy couldn't get enough of the two-staged engine to power all the planes Grumman could produce, hence a few planes were built as F4F-3A with a single-stage engine. As of December 7, 1941, the U.S. Navy was still in the process of replacing the F2A Buffalos on its carriers with F4Fs. In late 1941 Grumman shifted from building the F4F-3 to the F4F-4. Instead of going for a faster aircraft with the F4F-4, the Navy wanted a better protected, harder hitting fighter, so the F4F-4 was slower, had less range, and was much worse in a climb than the F4F-3. On the other hand, with folding wings, more F4F-4s could be carried on each carrier which made up for the loss in performance.


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## Shortround6 (Feb 11, 2017)

pinsog said:


> No doubt they should have been using the P&W 1830's instead.


The R-1830s were several hundred pounds heavier than the R-1820s and since the plane had initially been designed around R-1535s they may have been running into CG problems.


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## stona (Feb 11, 2017)

GrauGeist said:


> The Bf109's gear was actually designed to handle unimproved (grass) operations, this attribute would certainly mean it was rugged enough for carrier ops.



So was the Spitfire's and it clearly was not.

Cheers

Steve


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## pinsog (Feb 11, 2017)

Shortround6 said:


> The R-1830s were several hundred pounds heavier than the R-1820s and since the plane had initially been designed around R-1535s they may have been running into CG problems.[/QUOTE





Very true, they might have had to move radios or something farther back in the fuselage. Didn't they add lead weight to the tail of one Spitfire model after adding a heavier engine?


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## pinsog (Feb 11, 2017)

Top speed shouldn't change much. F4F3 at sea level 500 pound difference between fighter and overload was 1 mph, 278-277. Skyrocket had 871 pound difference between fighter and overload, also 1 mph speed loss, 312-311




A P43 would do 356 at 25,000 on 1,200 hp. I know a Skyrocket drag is higher but I think it would be considerably faster with double the power.


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## pinehilljoe (Feb 11, 2017)

I remember reading in Wings that Kelly Johnson had sketched a Naval P-38, but the tail hook was problematic. Anyone know if it got past concepts on the drawing board?


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## XBe02Drvr (Feb 11, 2017)

Shortround6 said:


> Thank you for the pictures. The smaller nacelle _may _be for the Twin Wasp _*Junior *_*R - 1535 *and not the Twin Wasp R-1830.


What's the diff? Frontal area of the 1535 was so close to the 1830 as to be practically insignificant. The 1820, on the other hand, was a barn door, besides being a boneshaker. I've ridden behind both 1820 and 1830. I'll take a Pratt any day.
Cheers
Wes


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## pinsog (Feb 11, 2017)

Conslaw said:


> If the goal would be to have a 350-mph fighter on carrier decks du 1941,IMHO the best bet would have been to rush out a production version of the XF4U without making the changes they actually made. Of course this wouldn't have been a very good aircraft, and it would have been an even worse carrier aircraft, but it would have been at least as good as its competitors, the navalized Airocobra and the F5F, because those aircraft would have had uncorrected problems of similar or greater magnitude if rushed into service in
> A short note about the P-43: The P-43 had roughly a 20-MPH speed advantage over the F4F.-3 with the same engine. This difference is in line with the difference in speed between the Spitfire and the Seafire, and it is roughly equal to the difference in speed between contemporary F4Us and P-47s. A navalized P-43 would have been no faster than the F4F-3.
> 
> The F4F-3 was a state-of-the-art carrier fighter in 1941. The A6M Zero was too. The designers of both aircraft just made different choices. The two-staged supercharger on the F4F-3 was an advanced technology of the time, and the Navy couldn't get enough of the two-staged engine to power all the planes Grumman could produce, hence a few planes were built as F4F-3A with a single-stage engine. As of December 7, 1941, the U.S. Navy was still in the process of replacing the F2A Buffalos on its carriers with F4Fs. In late 1941 Grumman shifted from building the F4F-3 to the F4F-4. Instead of going for a faster aircraft with the F4F-4, the Navy wanted a better protected, harder hitting fighter, so the F4F-4 was slower, had less range, and was much worse in a climb than the F4F-3. On the other hand, with folding wings, more F4F-4s could be carried on each carrier which made up for the loss in performance.




I never suggested the P43 as a carrier plane. Wasn't ever going to happen, no way, not ever. My point was, there were only 2, 350 mph land based fighters in the world that were being mass produced, the Spitfire and ME109. The US had a few in the pipeline, P38, P39 and P40. The P43 could have been ready earlier but they decided against even using it and only built a few and gave most to the chinese even though we had nothing to compete with it above 15-20,000 feet until the P38 FINALLY arrived in numbers.

F4f-3 was a pretty solid little fighter with good performance for it's time. F4F-4 was a pig. Period.
The P43 had a 20 mph speed advantage over the F4F-3, but they weighed exactly the same when they did the tests. Of course the P43 had 1,200 hp from SL to 25,000 so the higher it went the more the gap opened up. I am quite surprised that the P43 was 20 mph faster than the F4F-3 at sea level. They were exactly the same weight, so that would mean the Wildcat had more drag than the P43?????

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## tomo pauk (Feb 11, 2017)

Conslaw said:


> ...
> A short note about the P-43: The P-43 had roughly a 20-MPH speed advantage over the F4F.-3 with the same engine. This difference is in line with the difference in speed between the Spitfire and the Seafire, and it is roughly equal to the difference in speed between contemporary F4Us and P-47s. A navalized P-43 would have been no faster than the F4F-3.
> ...



The P-43 and F4F were not with same engine. Difference in wing size and P-43 available thrust above 20000 ft made the difference.



pinsog said:


> F4f-3 was a pretty solid little fighter with good performance for it's time. F4F-4 was a pig. Period.
> The P43 had a 20 mph speed advantage over the F4F-3, but they weighed exactly the same when they did the tests. Of course the P43 had 1,200 hp from SL to 25,000 so the higher it went the more the gap opened up. I am quite surprised that the P43 was 20 mph faster than the F4F-3 at sea level. They were exactly the same weight, so that would mean the Wildcat had more drag than the P43?????



WIng area of F4F was 260 sq ft, that of the P-43 was 222 sq ft; both employed reasonably thin wing profile. So the P-43 will make less of the drag (expressed as a force, not as coefficient). The P-43 concieved without turbo, but with 2-stage R-1830 should've been faster than F4F-3/-4.


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## pinsog (Feb 11, 2017)

I'm not surprised the P43 was faster above 15,000, but I was surprised that the P43 was 20 mph faster at sea level than the F4F-3 given that they were the same weight and same basic shape (short and fat)


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## tomo pauk (Feb 11, 2017)

As above - much bigger wing of the F4F is mostly to blame.


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## The Basket (Feb 11, 2017)

Why do you need 350mph naval fighters? In 1941?
For the Fleet Air Arm speed was less important as you were likely to encounter slow reconnaissance aircraft. Range was vital simply to get back to the carrier safely. Not for missions. It takes time to recover or launch aircraft and the carrier maybe miles away from where you left it. Also 2 seater was specified so you can have a navigator for over water flights. The Fairey Fulmar didn't do 350mph and started its service in 1941. The Fulmar had to carry fuel and that 2nd crewman so 350mph was not going to happen. But the Swordfish couldn't do 350mph either and neither could the Ar-196. So certainly where the FAA was concerned a navy Spitfire was not a peacetime need.

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## wuzak (Feb 11, 2017)

XBe02Drvr said:


> What's the diff? Frontal area of the 1535 was so close to the 1830 as to be practically insignificant. The 1820, on the other hand, was a barn door, besides being a boneshaker. I've ridden behind both 1820 and 1830. I'll take a Pratt any day.
> Cheers
> Wes



The R-1535 was ~4" smaller in diameter than the R-1830 - 44.15" to 48.03".

In frontal area that is 1,530.9sq.in for the R-1535 and 1,811.8sq.in for the R-1830. That is just over 18% more frontal area for the R-1830.

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## wuzak (Feb 11, 2017)

The Basket said:


> Why do you need 350mph naval fighters? In 1941?
> For the Fleet Air Arm speed was less important as you were likely to encounter slow reconnaissance aircraft.



What about carrier defence operations? Maybe speed is not a requirement, but climb more than likely was?


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## wuzak (Feb 11, 2017)

The Basket said:


> The Fairey Fulmar didn't do 350mph and started its service in 1941. The Fulmar had to carry fuel and that 2nd crewman so 350mph was not going to happen. But the Swordfish couldn't do 350mph either and neither could the Ar-196. So certainly where the FAA was concerned a navy Spitfire was not a peacetime need.



Weren't the FAA looking at a navalised Spitfire from 1938/1939?

They also had looked at a navalised Hurricane, but noted that the performance advantage the Hurricane held over the Ju 88, a likely opponent for fleet fighters, was marginal - when the naval equipment was added it was expected that margin would be non-existent.

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## wuzak (Feb 11, 2017)

It has been suggested to me that the P.1009 Typhoon Fleet Fighter to N.11/40, basically a navalised Typhoon, may have been a possibility.

I would think that such an aircraft would completely miss the 1941 service target.

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## The Basket (Feb 11, 2017)

The FAA was part of the RAF in 1938 so are the RAF going to give up it's Spitfires?


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## Elvis (Feb 11, 2017)

tomo pauk said:


> ...CV meaning 'carrier vessel'.
> Basically - how would've looked a speedy carrier-borne fighter for each country with CVs, whether the carriers are in service or in pipeline. Best case, but still plausible (no non-historical engines or arodynamic properties), with acceptable low-speed characteristics, plus the weapon and protection suite as used on the fighters of respective air services/forces in 1941. With useful range/radius.


For part of that year it would've been the Brewster Buffalo.
It beat out the Xf4F during trials and even the pilots who flew in those trials said that it was the better handling plane.
That first generation of Brewster fighters were ok, if not a little slow (I believe neither the Grumman nor the Brewster could achieve 350 mph, but it was what we had at the time).
It was the versions that came later on that ultimately led to the plane's demise.
Otherwise, the only other plane I can think of, off-hand, for Naval use, that would've been considered "speedy" might have been the Corsair.
Pretty sure it was in service in '41.


Elvis


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## XBe02Drvr (Feb 11, 2017)

wuzak said:


> The R-1535 was ~4" smaller in diameter than the R-1830 - 44.15" to 48.03".
> 
> In frontal area that is 1,530.9sq.in for the R-1535 and 1,811.8sq.in for the R-1830. That is just over 18% more frontal area for the R-1830.


We're talking twin row radials here. There's more to total engine/cowling drag (the pertinent parameter) than simple frontal area. I suggest the drag difference of a pair of 4 inch larger (4 foot diameter) engines would be pretty darn small compared to a pair of 1820 drag queens. We tore down, built up, and ran an 1820 at mech school. It's a veritable barn door. I'm 6' 5", and with the engine on its stand, (it had a short "club" prop) I could just reach a top cylinder sparkplug and had to get down on the floor for a bottom cylinder.
Cheers
Wes


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## wuzak (Feb 11, 2017)

XBe02Drvr said:


> We're talking twin row radials here. There's more to total engine/cowling drag (the pertinent parameter) than simple frontal area. I suggest the drag difference of a pair of 4 inch larger (4 foot diameter) engines would be pretty darn small compared to a pair of 1820 drag queens. We tore down, built up, and ran an 1820 at mech school. It's a veritable barn door. I'm 6' 5", and with the engine on its stand, (it had a short "club" prop) I could just reach a top cylinder sparkplug and had to get down on the floor for a bottom cylinder.
> Cheers
> Wes



The R-1820 is only 4-5" larger in diameter than the R-1830.


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## Shortround6 (Feb 11, 2017)

XBe02Drvr said:


> What's the diff? Frontal area of the 1535 was so close to the 1830 as to be practically insignificant. The 1820, on the other hand, was a barn door, besides being a boneshaker.



Frontal area of the R-1535 was about 10.5 sq ft, frontal area of the R-1830 was about 12.6 sq ft. Depending on the plane that _may _mean little difference (airliner or bomber with large fuselage and wing, size of engine nacelles is small portion of the total) or it may be a large difference, On the F5F the small nacelle may be roughly the size of the fuselage and the wing is smaller than the wing on an F4U. 
BTW the frontal area of an R-2800 is 14.8 sq ft. A Cyclone 9 is about 16.6 sq ft. 
A twin *needs *a crap load more power than a single to hit the same speeds.

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## pinsog (Feb 11, 2017)

Shortround6 said:


> Frontal area of the R-1535 was about 10.5 sq ft, frontal area of the R-1830 was about 12.6 sq ft. Depending on the plane that _may _mean little difference (airliner or bomber with large fuselage and wing, size of engine nacelles is small portion of the total) or it may be a large difference, On the F5F the small nacelle may be roughly the size of the fuselage and the wing is smaller than the wing on an F4U.
> BTW the frontal area of an R-2800 is 14.8 sq ft. A Cyclone 9 is about 16.6 sq ft.
> A twin *needs *a crap load more power than a single to hit the same speeds.



The XF5F Skyrocket would have had a crap load more power. Hellcat had 1650 hp at 25,000 feet. A Skyrocket with turbo P&W 1830's would have had 2,400 hp at 25,000 feet in 1941. Should weigh about the same after you add 4 50's, ammo. armor and self sealing tanks.

Everyone keeps talking about the terrible drag on the XF5F, but could someone please explain why the Skyrocket and the Hellcat go virtually the same speed on the same horsepower? 

Hellcat SL 310 mph 1890 hp
14,000 350 mph 1800 hp
17,000 362 mph 1800hp

Skyrocket SL 311 mph Not sure if its on 2,000 or 2,400 hp
14,000 346 mph 1,800 hp
17,300 356 mph Less than 1,800 

Above 17,300 the Skyrocket performance drops off because the 'barn doors' (Wright 1820) are only rated for 900 hp up to 14,000.


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## wuzak (Feb 12, 2017)

Where is your XF5F data coming from?


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## pinsog (Feb 12, 2017)

http://alternatewars.com/SAC/XF5F-1_and_XFL-1_PD_-_26_December_1942.pdf

Notice at the bottom, actually top of the 2nd page "performance based on flight tests"


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## wuzak (Feb 12, 2017)

pinsog said:


> http://alternatewars.com/SAC/XF5F-1_and_XFL-1_PD_-_26_December_1942.pdf
> 
> Notice at the bottom, actually top of the 2nd page "performance based on flight tests"



I found the data in this post by Tomo.



> The XF5F is tested as capable for 357-358 mph at 17300 ft, *no guns, no ammo*.



Presumably no armour as well.


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## pinsog (Feb 12, 2017)

wuzak said:


> I found the data in this post by Tomo.
> 
> 
> 
> Presumably no armour as well.



Agreed, but 900 pounds difference in the XF5F made 1 mph difference in speed.
900 pound difference in F6F-3 made a 3 mph difference in top speed
Speed on a light Mustang vs heavy Mustang I believe was 3 miles an hour.

Point is, add another 1,000 pounds of weapons, ammo, armor and self sealing tanks and it should still be right there with the Hellcat. If we add turbo charged P&W 1830's, we have lowered our drag and hp is now 2,400 from SL to 25,000 feet, all available in 1941 with no magic involved.

So, why was the XF5F Skyrocket able to do same speed, at same altitude on same horsepower as the Hellcat?


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## tomo pauk (Feb 12, 2017)

pinsog said:


> ...
> So, why was the XF5F Skyrocket about to do same speed, at same altitude on same horsepower as the Hellcat?



No guns' openings nor casings chutes on the X5F5, plus smaller wing than on the F6F. F6F has just one engine, but it features two intercoolers - those tend to increase drag. Flat, bullet-proof windscreen is more draggy than non-bullet-proof rounded/parabolic windscreen. No radio mast on the Skyrocket earns a few mph.


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## Shortround6 (Feb 12, 2017)

There is also the question of how much power the XF5F was really using. 

The more I look at it the more I believe the chart at alternate wars is being misinterpreted. 
For instance a chart on the F2A-3 with the same date gives the same power levels for the Cyclone R-1820-40. Does anybody really believe the F2A-3 really did 322mph at 14,000ft running at "Normal" power? Or did it use "Military" power which was pretty much the same as take-off power? FAA rated most of the G-200 series R-1820s at 1000hp for "take-off" at 14,200ft at 2500rpm and 44.5in for 5 minutes. This is without RAM so power at higher altitudes is dependent on the air intake and speed. 

Normal power (max continuous) was 900hp at 15,200ft at 2300rpm and 40in. 

And then we have what "shape" the XF5F-1 was in when those numbers were recorded.





After a number of drag reducing modifications were made? 
Note exhaust outlets. 




Not at all sure where turbos and more importantly, intercoolers and ducts go?
Switching to P&W R-1830s?
B-24 Nacelle without turbos




Carb intake at 12 o'clock inside cowl opening. Oil coolers under nacelle.
B-24 Nacelle with turbo




Carb intake and oil cooler are now at the 9 O'clock position and the opening at 3 O'clock is the intercooler scoop, Intercooler can be seen under the mechanics arms at rear of opening. You want 1200hp at 25,000ft you have to pay for it.

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## wuzak (Feb 12, 2017)

pinsog said:


> If we add turbo charged P&W 1830's, we have lowered our drag and hp is now 2,400 from SL to 25,000 feet, all available in 1941 with no magic involved.



They did for the XP-50, and one of the turbos blew up, which led to the airframe's destruction (pilot bailed out, aircraft crashed).

The XF5F first flew in April 1940.
The XP-50 first flew February 1941.

Having either of them available in 1941 was going to be a stretch,


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## pinsog (Feb 12, 2017)

WUZAK, as I said earlier, they would have to ditch the F4F-3 and only work on the Skyrocket. Unlike the Hellcat and Corsair, the technology was there in 1939, as proved by the P43. Not completely perfected, but there.

Shortround, I would definitely do the version you are showing with the longer nose and not the 1st version, but using P&W 1830's instead. Even if you ditch the turbos, you are still getting Hellcat performance. It is 35 mph faster than a Wildcat or Zero at sea level and 20 mph faster than a Spitfire MkII at sea level. It's 20 mph faster than a Zero at any altitude. 

Will the turbo and intercooler fit in the back of the lengthened nacelles? Where was the intercooler on a P43? The fit a turbocharged 1830 in a P43 in 1939 in the same sized package as an F4F-3 with a 20-25 mph speed advantage over a Wildcat at any altitude.


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## tomo pauk (Feb 12, 2017)

Some other US candidates:
- P-66
- F4F with turbo


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## pinsog (Feb 12, 2017)

I wondered about F4F with turbo myself since the P43 was about the same size and shape and it had a turbo


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## tomo pauk (Feb 12, 2017)

The F4F was bigger, wing area bigger by almost 20%. That will shave some speed from what P-43 was making, but will make wing loading favorable, same with low speed handling vs. P-43.


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## wuzak (Feb 12, 2017)

pinsog said:


> WUZAK, as I said earlier, they would have to ditch the F4F-3 and only work on the Skyrocket. Unlike the Hellcat and Corsair, the technology was there in 1939, as proved by the P43. Not completely perfected, but there.



The YP-43 aircraft were ordered in March 1939. The first delivery was in September 1940.



pinsog said:


> Shortround, I would definitely do the version you are showing with the longer nose and not the 1st version, but using P&W 1830's instead. Even if you ditch the turbos, you are still getting Hellcat performance. It is 35 mph faster than a Wildcat or Zero at sea level and 20 mph faster than a Spitfire MkII at sea level. It's 20 mph faster than a Zero at any altitude.



Of course the Spitfire II had an engine rated for a higher altitude than did the XF5F, and only one supercharger speed, so it suffered down low. But the Spitfire II was in full production, had armour, self sealing tanks, 2 x 20mm cannon and 4 x 0.303"mgs. The XF5F had none of that.




pinsog said:


> Will the turbo and intercooler fit in the back of the lengthened nacelles? Where was the intercooler on a P43? The fit a turbocharged 1830 in a P43 in 1939 in the same sized package as an F4F-3 with a 20-25 mph speed advantage over a Wildcat at any altitude.



Maybe you should be arguing for a navalised P-43?

Good question on where the intercooler was on the Lancer.


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## tomo pauk (Feb 12, 2017)

wuzak said:


> ...
> Good question on where the intercooler was on the Lancer.



The manual for the P-43 states that intercooler is located prior the carburetor, job being the removal of excess heat from the compressed air.


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## wuzak (Feb 12, 2017)

tomo pauk said:


> The manual for the P-43 states that intercooler is located prior the carburetor, job being the removal of excess heat from the compressed air.



But where in the airframe?

Is the turbo to the rear?


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## tomo pauk (Feb 12, 2017)

I've had the picture of the plumbing of P-43 turbo system, unfortunately can't find it today. 
The turbo was at the rear. (Pictures) Single waste gate, the most visible, longitudinal duct is for exhaust gasses.


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## wuzak (Feb 12, 2017)

tomo pauk said:


> I've had the picture of the plumbing of P-43 turbo system, unfortunately can't find it today.
> The turbo was at the rear. (Pictures) Single waste gate, the most visible, longitudinal duct is for exhaust gasses.




Thanks Tomo.

I am having a hard time seeing where air would enter to cool an intercooler.


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## Shortround6 (Feb 12, 2017)

Here is a website with many good pictures of the P-43:
Forums / USAAF / USN Library / Republic P-43 Lancer - Axis and Allies Paintworks

Please note there are several pictures of the inside of the rear fuselage showing ductwork. 

It would _appear _that the P-43 system was sort of a trial run for the P-47. Turbo to the rear of the cockpit. Air intakes under the engine in the nose with the oval opening. Ducts and exhaust pipe running back and forth. Location of the intercooler is not positive _but_ there are only a few possible locations based on air outlets. One is a slot at the very bottom of the cowl pretty much in line with the adjustable cooling flaps. Unlikely due to space constraints. The next outlet is a door/flap in the left wing root (don't know if there is one on the right to match.) in front of the landing gear. Seems small and may be possible location of the oil cooler outlet, P-47 oil cooler outlets were just slightly forward of this location. 3rd is a flap on the bottom of the aircraft behind the turbocharger. P-47 used lateral exits. 

As to performance. Chart at WW II aircraft performance shows a top speed of about 290-293mph ? at sea level which is NOT 30mph faster than a F4F-3 more like 15mph and speed at 15,000ft for the *YP-43* is 339mph. The YP-43 is flying with about 145 gallons of fuel and 250lbs of armament (two .50 cal guns go about 150lbs. .50 cal ammo is 30lbs per 100 rounds).
Now weight is not a big detriment to speed, it has a much greater impact on climb. 
As to carrier use (not the P-43 as it stands) zero wind take-off for the P-43 at 6913lbs was 1070ft and landing speed was 93mph. Landing was using full flap. 
The F4F-3 at 7432lbs (over weight fighter ) was 748ft and stalling speed without power at that weight was 78mph. With fuel burned off it was lower. Please take these figures into consideration when thinking about carrier fighters. 
In order to be a carrier fighter the plane actually has to take-off and land from the majority of carriers in a particular navy. And some Navies had slow carriers with short decks.

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## pinsog (Feb 12, 2017)

I've said it on this thread about 5 times, A P43 WILL NEVER BE A CARRIER FIGHTER, EVER EVER EVER EVER

Shortround, in thread 59 I said P43 is 20-25 mph faster than an F4F-3, not 30. BUT it is 30 mph fast up high, F4F-3 is 326 at 22,000. A P43 is 356 at 25,000. That is 30 mph 3,000 feet higher. At 22,000 feet the F4F-3 performance is already dropping and will only get worse. F4F is doing 312 at 14,200, P43 is doing 339 at 15,000, thats 27 mph difference. 

P43 started out with 2 50's synchronized and 2 30's in the wings. It then replaced wing 30's with 2 wing 50's and then eventually moved all 4 50's to the wings.

They should have fixed/redisigned wing to accommodate normal fuel tanks instead of wet wings and deployed it to Pacific land basis instead of P40's and land based F4F's.


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## Shortround6 (Feb 12, 2017)

Sorry I wasn't clearer. Just using the P-43 as an example of _why _you can't take land plane X and hang a hook on it and presto-chango have a Carrier fighter. 

I have my doubts about later P-43s being quite as fast as the YP-43 also. 

I would also love to see a photo of a P-43 with wing guns only. Often reported in print but actual evidence seems a bit thin. 

Using the P-43 as evidence that the turbo installation didn't have a fair amount of drag penalty doesn't hold up well due to the difference in wing size and wing characteristics. Not only did the F4F have a bigger wing but high lift wing sections are rarely low drag wing sections. 
You need a closer airframe to make a comparison with.

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## Elvis (Feb 13, 2017)

Something to remember with the P-43 and possibly the P-35....Those planes were not designed and built for carrier service,
To do that, the airframe and possibly the landing gear would have to be strengthened...then there's the marinization process, to help the thing survive at sea.
All of this adds weight and thus, degrades performance.
While on paper, the P-43 _seems_ to outclass the F4F-3, you have to remember the Grumman was a flying tank because it was designed and built as a carrier airplane.
What you need to do is marinize the P-43 first, then compare subsequent performance numbers to whatever F4F you choose...I bet you'll find the performance numbers to be closer than what they are now.
As for the radial engines mentioned, again, we go back to weight.
All the twin row engines mentioned are around 1500 lbs., but most of the variations of the R-1820 are around 1000lbs.
...that's a 500 lb. difference and that can have a pretty fair effect on overall performance.
Yeah, the Wright engines were quite broad, but they were also lighter, yet were capable of similar power output.
This is probably what manufacturers noticed with that engine and why it was such a popular choice.


Elvis


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## parsifal (Feb 13, 2017)

not necessarily the case that performance was downgraded by navalisation. sea hurricane had the same or better performance than new hurricane Is or IIs, and in some instances, published performance for the sea hurricane shows slightly better performance. Some opportunities were taken to improve aerodynamics and the like partly explains this

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## Elvis (Feb 13, 2017)

Sea Hurricane also benefitted from a more powerful version of its engine and a different prop.
Could've been enough to _bring things back to square_, if you catch my drift. =)


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## Shortround6 (Feb 13, 2017)

Elvis said:


> As for the radial engines mentioned, again, we go back to weight.
> All the twin row engines mentioned are around 1500 lbs., but most of the variations of the R-1820 are around 1000lbs.
> ...that's a 500 lb. difference and that can have a pretty fair effect on overall performance.
> Yeah, the Wright engines were quite broad, but they were also lighter, yet were capable of similar power output.
> This is probably what manufacturers noticed with that engine and why it was such a popular choice.



The R-1820 hadn't weighed 1000lbs since the "F" series of 1934/35. The "G" series (introduced in 1935/36) went about 1153-1210lbs with reduction gear and about 1105-1114lbs with direct drive. The "G-100" series went 1255-1290 introduced in 1937 and the "G-200" went 1290-1338lbs starting in 1939. Some of the early models stayed in production for certain applications after newer models came out so there was quite a bit of cross over. 

The R-1535 went _around _1100lbs and all production versions had a single speed supercharger. The R-1830 varied quite a bit, a few of the early ones were down around 1200-1300lbs (power was also around 900hp) but the majority of production engines, even before WW II were 1400lbs and up. P & W was working on two stage superchargers and didn't get around to fitting a 2 speed drive to the single stage until several years after Wright did. Perhaps another reason for some choices of engine?


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## Shortround6 (Feb 13, 2017)

Some land aircraft like the Hurricane and Spitfire had large wings to suit them to the small grass airfields, what with the fixed pitch props they needed all the help they could get for take-off. Low landing speeds also suited the Grass fields. This made transition to carrier decks easier. Planes with higher wing loadings and/or different airfoils may have had a much harder time. 
Flight characteristics near stall also play a big part, a plane that maintains stability down to or just above stall is a big plus compared to one that starts to wander (yaw) or rock or porpoise as it approaches stall. Effectiveness of the controls at or near stall is also important. Some aircraft tended to loose control effectiveness at low speeds. Being unable or only slowly correct a mild swing/drift or wing drop could be fatal to a carrier plane while being within acceptable for a land plane. 
Large control surfaces also mean more drag so the quest for 350mph carrier fighters on limited power has another complication.


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## stona (Feb 13, 2017)

Shortround6 said:


> Flight characteristics near stall also play a big part, a plane that maintains stability down to or just above stall is a big plus compared to one that starts to wander (yaw) or rock or porpoise as it approaches stall.



The Spitfire/Seafire was a notorious 'floater'.
Something as simple as the instrumentation could have a serious effect too. The Spitfire ASI was designed so that close to landing/stall speeds the travel across the dial between 'safe landing' and 'inevitable crash' was somewhat smaller than the natural oscillation of the pointer. Landing on grass airfields, when the difference between the stall speed and landing speed was much larger this was not an issue. However, for deck landings, where the difference was very small indeed, much smaller than on US aircraft designed for carrier operations, it was very much an issue. It led to pilots adding a few knots 'for the wife and family', coming in a little fast and then floating over the arrestor wires and into the barrier(s) or slamming into the deck imparting forces at angles for which the Spitfire undercarriage and airframe was never designed. The consequences of either were often serious for the pilot and terminal for the aircraft.
Cheers
Steve


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## Elvis (Feb 13, 2017)

Shortround6 said:


> The R-1820 hadn't weighed 1000lbs since the "F" series of 1934/35. The "G" series (introduced in 1935/36) went about 1153-1210lbs with reduction gear and about 1105-1114lbs with direct drive. The "G-100" series went 1255-1290 introduced in 1937 and the "G-200" went 1290-1338lbs starting in 1939. Some of the early models stayed in production for certain applications after newer models came out so there was quite a bit of cross over.
> 
> The R-1535 went _around _1100lbs and all production versions had a single speed supercharger. The R-1830 varied quite a bit, a few of the early ones were down around 1200-1300lbs (power was also around 900hp) but the majority of production engines, even before WW II were 1400lbs and up. P & W was working on two stage superchargers and didn't get around to fitting a 2 speed drive to the single stage until several years after Wright did. Perhaps another reason for some choices of engine?


Oh probably, but you just backed up that part of my post. Thanks buddy! You're ok!  =)

Elvis


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## Elvis (Feb 13, 2017)

Shortround6 said:


> Some land aircraft like the Hurricane and Spitfire had large wings to suit them to the small grass airfields, what with the fixed pitch props they needed all the help they could get for take-off. Low landing speeds also suited the Grass fields. This made transition to carrier decks easier. Planes with higher wing loadings and/or different airfoils may have had a much harder time.
> Flight characteristics near stall also play a big part, a plane that maintains stability down to or just above stall is a big plus compared to one that starts to wander (yaw) or rock or porpoise as it approaches stall. Effectiveness of the controls at or near stall is also important. Some aircraft tended to loose control effectiveness at low speeds. Being unable or only slowly correct a mild swing/drift or wing drop could be fatal to a carrier plane while being within acceptable for a land plane.
> Large control surfaces also mean more drag so the quest for 350mph carrier fighters on limited power has another complication.


Likely why the reason for the huge wings on the F4U, as well...possibly that giant prop, too.


Elvis


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## JAG88 (Nov 7, 2017)

pinsog said:


> How do you guys think an ME109 would handle controlled crash landings on a carrier day after day?(Spitfire didn't like it)
> How well would that tiny little fighter handle the weight gain of being navalized?



The wing was enlarged and the added weight wasnt that much (200Kg), and it got a more powerful engine (N). The landing gear was widened and strengthened as well.



Shortround6 said:


> It was not just the aircraft but the carriers and operating doctrine. It is no great trick to catapult small fighters into the air with drop tanks but range is not based on individual aircraft but the range of the group. First planes up have to orbit until the last planes are up. If the carrier only has two catapult s how long does it take to get the group in the air? The US planned on flying off, not catapult for a higher launch rate.
> You are also back to operational radius depending on internal fuel for fighting, cruise home and a bigger reserve than land operations, you only have one landing "area" (task group) with a limited number of runways. You have to find it and then have enough fuel for ALL planes to land (including time out for several bad landings).
> What is the *range *of the 109 with 10-15 minutes of combat and 30 minutes or more of reserves for finding the carrier and queuing up to land taken away from the internal fuel?



Ju 87s and 109s would use the catapults, the Fi 167s would not.

Each catapult could launch 1 aircraft per minute, that is a launch every 30s, so about 4 minutes for the biplanes and then 10 minutes to catapult the other aircraft. So, about twice as long as a IJN launch.



stona said:


> The Spitfire/Seafire was a notorious 'floater'.
> Something as simple as the instrumentation could have a serious effect too. The Spitfire ASI was designed so that close to landing/stall speeds the travel across the dial between 'safe landing' and 'inevitable crash' was somewhat smaller than the natural oscillation of the pointer. Landing on grass airfields, when the difference between the stall speed and landing speed was much larger this was not an issue. However, for deck landings, where the difference was very small indeed, much smaller than on US aircraft designed for carrier operations, it was very much an issue. It led to pilots adding a few knots 'for the wife and family', coming in a little fast and then floating over the arrestor wires and into the barrier(s) or slamming into the deck imparting forces at angles for which the Spitfire undercarriage and airframe was never designed. The consequences of either were often serious for the pilot and terminal for the aircraft.
> Cheers
> Steve



One of the solutions the Germans implemented to make the 109T viable was to add spoilers to allow for a power on approach and prevent floating.

A LOT more work and development went into the 109T than into the improvised RN navalizations.


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## stona (Nov 7, 2017)

A lot more work was required because a Bf 109 was even less suitable for carrier operations than a Spitfire. 

It's why the 'T' was quite different from a standard 'Emil', the extra 1.18m on the wingspan being the most obvious of the 'improvements', whereas an early Seafire was not markedly different from a Spitfire.

At least the Bf 109 T would have had the benefit of a much longer deck for landing than those of British carriers, catapult launches and a surprisingly sophisticated arrestor system (by DEMAG), had the Graf Zeppelin ever become operational.

Cheers

Steve


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## JAG88 (Nov 7, 2017)

stona said:


> A lot more work was required because a Bf 109 was even less suitable for carrier operations than a Spitfire.
> 
> It's why the 'T' was quite different from a standard 'Emil', the extra 1.18m on the wingspan being the most obvious of the 'improvements', whereas an early Seafire was not markedly different from a Spitfire.



How so? The 109 was very docile in the approach to landing, very stable, and the slats allowed you to ride the stall with confidence, something that a Spit pilot would not do if he wanted to live, hence the extra speed and consequent floating.

Best


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## Jugman (Nov 7, 2017)

wuzak said:


> Thanks Tomo.
> 
> I am having a hard time seeing where air would enter to cool an intercooler.



The intercoolers were located about two feet in front of the turbo. Air was supplied from the two inboard intakes under the engine. It looks like they discharged into the fuselage just like the B-17 did with it's wing mounted units.


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## davparlr (Nov 8, 2017)

P-66 was close. Maybe with the F4F engine it could reach 350 at a higher altitude. It did need some attention for some fixes and added weight of strengthening the structure and landing gear would have affected climb but not so much top speed. Wing area was a bit small at 197 sqft., but it was only 12 sqft less than the carrier qualified F2A. Weight was a bit heavier, though. Still the wing loading of the P-66 at gross was 36 lb/sqft was less than the F4U-1 at 38 lb/sqft. So some weight leeway was available.

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## Koopernic (Nov 8, 2017)

JAG88 said:


> How so? The 109 was very docile in the approach to landing, very stable, and the slats allowed you to ride the stall with confidence, something that a Spit pilot would not do if he wanted to live, hence the extra speed and consequent floating.
> 
> Best



The Me 109T lead to the Me 109G based Me 155 also with extended wings, I think they were laminar flow profile like the Me 309 so it would have been quite fast despite the enlarged wing.. When the carrier program was cancelled the Me 155 was retargeted as a high speed bomber and high altitude aircraft. Due to engineering capacity shortages at Messerschmitt it was transferred to Blohm and Voss and became the BV155. Here it was heavily re-engineered thereby making manufacture impossible. The BV155 definetly had laminar Profile wings. This was in part driven by changing over from DB605 and then the high altitude DB628 (essentially a DB605 with a variable pitch 2 stage supercharger) and then the DB603 with a turbo charger. It did fly, service ceiling about 56,500ft.

The original Me 155 carrier version was expected to have a speed of 402 mph with the DB605A. This is about the same as the Me 109G1 at 1.3ATA or the Me109G6 at 1.42ATA.

It’s curious to think of the “T” carrier version of the Me 109 to have continued. A Me 109F or Me 109G with the extended wings.

The extended wings would have provided for high altitude flight, better turn radius, STOL, a place to store fuel and a place to locate extra guns without resorting to the high drag Bulges of the Me 109G6 gun covers.


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## stona (Nov 9, 2017)

JAG88 said:


> How so? The 109 was very docile in the approach to landing, very stable, and the slats allowed you to ride the stall with confidence, something that a Spit pilot would not do if he wanted to live, hence the extra speed and consequent floating.
> 
> Best


The Seafire had to fly very close to the stall to make a carrier landing, three knots above the engine on stall speed or just 1.05 Vse. For comparison, US Carrier aircraft were designed to land at 1.2Vse, a relatively large margin.
The extra few knots ('for the wife and kids') were usually added because the air speed indicator had such a coarse scale, incapable of reading that accurately,the needle vibrating over an eighth of an inch representing about 10 knots, at least according to Seafire pilots who were there and survived.
Experienced pilots ignored it and flew by the seat of their pants, trusting the trusting the tail buffet stall warning to tell them they were about to fall out of the sky.
The 'float' was actually caused not by excessive speed but by the inescapable consequences of the V squared law. When a pilot cut the power to land and the slipstream speed reduced, the extra lift given by the positive angle on the elevator also reduced. The tail then lost a good deal of its lift and inevitably fell. The consequence of this was an increase in mainplane incidence (as if the pilot had pulled back on the stick) and corresponding increase in mainplane lift leading inevitably to the 'float'. This was a function of the Seafire and all but the Mk I Spitfire's aerodynamics. Most aircraft, including the Bf 109, have 'negative lift' on the stable tail surfaces, particularly in a landing configuration, meaning that the cutting of the power produces, at worst, a nose down pitch. This was quite pronounced on the Bf 109 T and considered, if not a problem, then something that pilots would need to be aware of.

The Bf 109 could land with a larger margin over the stall (about 7 knots) thanks to the very good arrester system, but this was not a function of any quality of the aircraft. Landing at 128 kph an arrested landing run of just 26m with a deceleration force of 2.8g was attained in tests.
The longer wing and the 'auftriebzerstorer' made it safer to land. Such modifications were never considered necessary on the Seafire, even later versions, but then the Spitfire had a much more sophisticated wing design, not requiring slats or other 'high lift' devices to increase lift at the lower end of its speed range.

Then we come to the undercarriage! Both aircraft were designed with narrow track undercarriages (remarkably similar track in fact) and for operation of grass fields. Neither was ideal for carrier operations, but the modified struts used on the Bf 109 T did nothing to improve the _horrible_ geometry of the Messerschmitt system. It is true that more than 500 test landings were made without a serious accident at Travemunde, but that is not representative of service pilots landing the aircraft on a carrier deck at sea. It did have some serious accidents in development, very nearly killing none other than Fritz Wendel in April 1941. Whether the Messerschmitt would have been any safer or more successful than the Seafire in real world operations we'll never know. I'd be amazed if it was any better. 

Both were aircraft designed with no consideration of carrier operations. Nothing about them was really conducive to making a successful carrier aircraft. The extensive modifications to the 'Emil' may have made it capable of carrier operations, just as adding a hook and making a few minor modifications did the same for the Spitfire, but neither would ever compare to aircraft specifically designed for such a role.

Cheers

Steve

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## JAG88 (Nov 9, 2017)

Thx for the detailed response. 

I would argue that the spoiler would have certainly helped with the floating and solved one of the main issues of the Seafire and that the stall behaviour in landing configuration of the 109 was better than the Spitfire's giving ample warning and chance to recover making it safer to land, as far as that aspect is concerned. The arrestor system made a faster landing posible, but if desired a 109 pilot could approach its stall speed with a confidence that no Spit pilot would, thst was a natural advantage of the 109 and an important one for a carrier aircraft.

Would the 109 have suffered as much as the Seafire did at Salerno?

The longer wing was a mere extension of the original one IIRC, not much of a modification.

I agree that strengthened or not the landing gear would have been its main issue.

I see the fact that the improvised Seafire was made to work more as a matter of need rather than suitability per se, the RN would have benefitted from some development work on the spit as the KM requested on the 109 IMHO.


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## stona (Nov 9, 2017)

The Spitfire gave ample warning of the stall, it's how experienced pilots landed it so very close to the power on stall speed, just three knots above Vse.
The tail buffet stall warning was often premature in service aircraft, anything that interfered with the airflow over the wing root could cause an early stall warning and many service aircraft had things that could cause this. The two principle culprits were badly fitting engine cowlings and gun camera hatches. This was a critical area of the wing and anything disrupting the airflow here, at low speeds, could cause the whole wing to stall. It's not therefore surprising that many pilots would ad a few knots 'for the wife and kids'.
Cheers
Steve

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## JAG88 (Nov 9, 2017)

stona said:


> The Spitfire gave ample warning of the stall, it's how experienced pilots landed it so very close to the power on stall speed, just three knots above Vse.
> The tail buffet stall warning was often premature in service aircraft, anything that interfered with the airflow over the wing root could cause an early stall warning and many service aircraft had things that could cause this. The two principle culprits were badly fitting engine cowlings and gun camera hatches. This was a critical area of the wing and anything disrupting the airflow here, at low speeds, could cause the whole wing to stall. It's not therefore surprising that many pilots would ad a few knots 'for the wife and kids'.
> Cheers
> Steve



I apologize, I was thinking of the Sea Hurricane and its wing drop, dont you just love aging?


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## stona (Nov 9, 2017)

JAG88 said:


> dont you just love aging?



Oh yes, I know the feeling well 
Cheers
Steve


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## pinsog (May 8, 2019)

tomo pauk in thread #60 mentioned a turbo F4F. I had thought about it before but until I finally ran some numbers I didn't realize how big a difference it would actually make.

Original 2 speed 2 stage P&W R-1830-76: 
1200 hp for takeoff 
1100 hp from SL-2500 feet
1050 hp from 4800-11000 feet
1000 hp from 12200-19000 feet

with a P&W R-1830-47 with a turbocharger (same engine as the P43 Lancer) 
1200 hp from SL-25000 feet 

SL speed increases from 278 to 286
Speed at 5500 goes from 295 to 308
Speed at 13000 goes from 313 to 332
Speed at 19000 goes from 330 to 350
Speed at 22000 goes from 326 to 351

The F4F-3 speed numbers above included 150 pounds of armor and a self sealing fuel tank.

Drag should be identical, F4F-3 already has an intercooler so just plumb turbo into existing intercooler. I believe the weight would remain nearly the same as the weight of the turbo, 135 pounds, would be offset by the lighter single speed single stage engine that goes with it. I believe the best place for the turbo would likely be where it was on the P43 Lancer, but the pipe/plumbing would probably needed to have been done in the original prototype, not sure if there was room for the exhaust pipe and return pipe to be retrofitted later.
I also believe climb would be substantially improved as well as you would gain 100 hp down low, 200 hp from 12200-19000. 

At 25000 feet HP jumps from 860 to 1200. 

Performance virtually equal with the Spitfire mkII at 5000 feet and surpasses it above 20,000 and should continue to increase with altitude. (I can't find any speed data on the F4F-3 above 22000 feet)

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## XBe02Drvr (May 8, 2019)

pinsog said:


> the pipe/plumbing would probably needed to have been done in the original prototype, not sure if there was room for the exhaust pipe and return pipe to be retrofitted later.


I've actually seen (and sat in) a spacious, luxuriously appointed passenger compartment below and behind the cockpit of an FM2. Now I know an FM2 isn't an F4F-3, but they can't be all that different. I was impressed with the spaciousness inside that barrel fuselage. Even the "busy" area around the landing gear actuators didn't have the crammed in look I was used to seeing in more modern aircraft. And remember, the -3 had a hand crank manual retraction system, so even less machinery down there.
Cheers,
Wes

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## pinsog (May 8, 2019)

Do you know what diameter the exhaust pipe from the engine to the turbo would have to be? Pipe from the turbo back to the engine?


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## tomo pauk (May 8, 2019)

I'm not sure about diameter of the piping, however, there was the XF4F-5, with R-1820 + turbo. Seems like the B-17Bs were delivered with similar powerplant from second half of 1939 on - 1200 HP up to 25000 ft. No problems encountered when flying to Brazil and back (in several 'hops', of course).
Might be an interesting read: link


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## XBe02Drvr (May 9, 2019)

tomo pauk said:


> the B-17Bs were delivered with similar powerplant from second half of 1939 on - 1200 HP up to 25000 ft.


That's not actually what your Joe Baugher page says. It describes a (no mention of a turbocarger) -51 engine in the B17B that can only manage 900 hp at 25,000, which is 400 ft ABOVE its service ceiling.
Cheers,
Wes


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## pinsog (May 9, 2019)

An F4F-3 will climb to 10000 feet in 3.5 minutes on 1050 hp and 20000 feet in 7.6 minutes at 1050 hp up to 12000 feet and then 1000 hp from 12000-20000 feet.....(light on fuel)
Is there a way to calculate the climb to 10000 or 20000 feet if you have a turbocharged engine with 1200 hp available from sea level up to 25000 ft?


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## tomo pauk (May 9, 2019)

XBe02Drvr said:


> That's not actually what your Joe Baugher page says. It describes a (no mention of a turbocarger) -51 engine in the B17B that can only manage 900 hp at 25,000, which is 400 ft ABOVE its service ceiling.
> Cheers,
> Wes



Indeed, no turbo is mentioned.
The speed-at-altitude and ceiling figures are in major mismatch at J.B's page, though.



pinsog said:


> ...
> Is there a way to calculate the climb to 10000 or 20000 feet if you have a turbocharged engine with 1200 hp available from sea level up to 25000 ft?



Maybe this might be of use: link


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## pinsog (May 9, 2019)

I have been using that link tomo pauk. In fact, it is one reason I finally did the caculations to see what a turbocharged F4F-3 would do. It appears to me that the smaller wing of the P43 gives it a higher top speed down low, while the larger wing of the Wildcat gives it a better climb until the power of the P43 overcomes the higher lift of the F4F-3. Also, apparently, top speed above 20000 feet appears to be about the same (if they were both turbocharged) making me think that the thinner air at altitude makes less difference to the slightly draggier F4F-3.

Looks to me like a turbocharged F4F-3 was a missed opportunity from 1940-mid 1943


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## drgondog (May 9, 2019)

GrauGeist said:


> There was a P-51 (P-51-NA), s/n 41-37426 (BuNo. A57897) that was evaluated by the USN long before they considered the P-51D.
> 
> View attachment 365171



Dave - doable but while production of the NA-73 began in spring 41, modifying the Mustang for just carrier landing qual - much less hosting a nasty inline/glycol cooled engine was Never going to be bought by USN. The earliest possible date for Carrier qual 'qualified' acceptance would have been perhaps mid 1942 for the NA-73. The NA-91 shown above first flew in May, 1942 and was acquired from Brit order.At that time the F4U had much more upside. Further, adding wing racks/plumbing was NA-97 (A-36) first flying in Fall 1942. Earliest delivery to squadron level would have been mid 1943 if USN committed in April 1942.

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## Elvis (May 9, 2019)

Tomo Pauk,

Could you please explain "Calibrated Climbing Speed" to me?
I'm having a little trouble understanding the figures they show in that link you posted.


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## pinsog (May 9, 2019)

Elvis said:


> Tomo Pauk,
> 
> Could you please explain "Calibrated Climbing Speed" to me?
> I'm having a little trouble understanding the figures they show in that link you posted.



Are you referring to post #95? I meant to show the F4F-3 climb times to 10000 feet and 20000 feet while also including the hp of the engine at certain heights. 1100 hp from SL-3500 feet, 1050 from 4800-11000 feet, 1000 hp from 12,200-19000 feet.

My question is, if an F4F-3 was turbocharged with 1200 hp from SL-25000 feet, weight and drag unchanged, what would the time to climb be up to 10000 and 20000 feet? Is there a way to calculate the increased climb rate?


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## GrauGeist (May 9, 2019)

drgondog said:


> Dave - doable but while production of the NA-73 began in spring 41, modifying the Mustang for just carrier landing qual - much less hosting a nasty inline/glycol cooled engine was Never going to be bought by USN. The earliest possible date for Carrier qual 'qualified' acceptance would have been perhaps mid 1942 for the NA-73. The NA-91 shown above first flew in May, 1942 and was acquired from Brit order.At that time the F4U had much more upside. Further, adding wing racks/plumbing was NA-97 (A-36) first flying in Fall 1942. Earliest delivery to squadron level would have been mid 1943 if USN committed in April 1942.


Yeah, we had a lengthy discussion several years ago about water-cooled aircraft versus the USN mindset by the late 30's - also, their existing carriers would have had to be retrofitted for Glycol storage and the carriers under construction would have to be modified as well. Considering the USN was under severe budget constraints by 40/41, I honestly doubt the P-51 or XFL were ever seriously considered beyond testing (pre-war).
The USN was actually interested in the P-51D and P-51H later on, but that's for another discussion.

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## pinsog (May 9, 2019)

Elvis said:


> Tomo Pauk,
> 
> Could you please explain "Calibrated Climbing Speed" to me?
> I'm having a little trouble understanding the figures they show in that link you posted.



Elvis, I just realized you weren’t talking to me and on a completely different subject. I guess I should read posts a little closer.

You were talking about the P43 graph. My mistake

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## fliger747 (May 12, 2019)

A misunderstanding of what the "tail" does on an airplane. To produce positive stability the tail produces downforce. At the "cut" on a power on approach to landing The downforce on the tail reduces and the NOSE drops. This mains first contact would often cause the "bounce" as the tail then dropped at impact increasing the AOA and the plane wanting to re fly for a last gasp, perhaps over the wires. 

From a previous post...

The 'float' was actually caused not by excessive speed but by the inescapable consequences of the V squared law. When a pilot cut the power to land and the slipstream speed reduced, the extra lift given by the positive angle on the elevator also reduced. The tail then lost a good deal of its lift and inevitably fell.

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## XBe02Drvr (May 12, 2019)

fliger747 said:


> At the "cut" on a power on approach to landing The downforce on the tail reduces and the NOSE drops. This mains first contact would often cause the "bounce" as the tail then dropped at impact increasing the AOA and the plane wanting to re fly for a last gasp, perhaps over the wires.


Or in the case of a nosedragger, it hits nosegear first, then mains, with nose bouncing up, plane relaunching into the air, only to stall and drop in on its nose again, while the panicked student freezes on the controls with the throttle not all the way off, and the plane crowhops off the end of the runway and into the thules. (or off the angle deck into the drink)
I saw this happen to a student carrier qualing on the Lex in a T-28. He crow hopped over all four wires and disappeared over the angle as the LSO screamed "POWER, POWER", but he managed to catch it with power before it hit the water. From our vantage point in the PLAT camera station on the island, we saw a lot of spray churned up by his prop and thought he'd gone in, but he reappeared skimming the wavetops. Needless to say, they bingoed him right back to Whiting. I'm guessing that was the end of his aviation career.
Cheers,
Wes


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## Kevin J (May 12, 2019)

parsifal said:


> Well, the elephant in the room are the German and British conversions that coulda and shoulda, but never eventuated (well not quite true, the Me109T, the conversion of the E-3 was completed, but never flew from a carrier, the me 109f was only ever projected, whilst the seafire did happen and was used from a carrier but arrived vary late for the party). I am referring to the Me-109T and Me 109F conversions (mooted) for the failed KM carrier. For the British the missing thoroughbred was the seafire II, which the admiralty had wanted since at least 1939, but consistently rejected by an indifferent, even hostile air ministry.
> 
> 
> The seafire needed some work, undoubtedly, but none of it was technically infeasible. The chief changes required were wing folding, strengthened landing gear, redesigned and widened landing gear as opposed to the narrow tracked types accepted for the land based version.
> ...


I'd dispute that. The Seafire needed the strengthened wing of the Spitfire Vc. I certainly don't believe it could have arrived earlier.


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## Kevin J (May 12, 2019)

I think the closest you could get would be a Hurricane IIa, no wing folding, cleaned up, arrestor hook only, individual exhaust stubs. My estimate 348 mph. Alternately, Hawker Hotspur with Rolls-Royce Vulture, under fuselage radiator, turret replaced with fuel tank and armament in wings N.B. Henley flew with Vulture. Problem is the radiator would be a big scoop for water if the plane had to ditch. Perhaps not the safety standards required of a plane that could have flown before WW2. Or maybe a Sea Defiant, turret replaced with fuel tank, armament in wings, arrestor hook, upwards wing folding, optional catapult attachments. Early version Spitfires I/II/Va/b, definitely not, its too fragile.


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## wuzak (May 12, 2019)

Kevin J said:


> I think the closest you could get would be a Hurricane IIa, no wing folding, cleaned up, arrestor hook only, individual exhaust stubs. My estimate 348 mph.



Since the land plane version of the Hurricane II couldn't do that, it would be very doubtful that a Sea Hurricane could.




Kevin J said:


> Alternately, Hawker Hotspur with Rolls-Royce Vulture, under fuselage radiator, turret replaced with fuel tank and armament in wings N.B. Henley flew with Vulture. Problem is the radiator would be a big scoop for water if the plane had to ditch. Perhaps not the safety standards required of a plane that could have flown before WW2.



The Henley was used as a test bed for the Vulture.

Hawker had difficulty with the under-fuselage radiator on the Tornado, moving it to the nose after early flights. It is hard to know if Hawker could have made it work for the Hotspur in conjunction with the Vulture.

And then, of course, you are stuck with an engine which is out of production by early 1941, only 500 or so having been made.




Kevin J said:


> Or maybe a Sea Defiant, turret replaced with fuel tank, armament in wings, arrestor hook, upwards wing folding, optional catapult attachments. Early version Spitfires I/II/Va/b, definitely not, its too fragile.



Maybe a Sea Defiant could work, if they weren't required for other duties.

The proposals for the early Spitfire based Seafire had revised wings with folds and strengthening. One even had a trapezoidal wing, rather than the elliptical wing.


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## Shortround6 (May 12, 2019)

Kevin J said:


> I think the closest you could get would be a Hurricane IIa, no wing folding, cleaned up, arrestor hook only, individual exhaust stubs. My estimate 348 mph. Alternately, Hawker Hotspur with Rolls-Royce Vulture, under fuselage radiator, turret replaced with fuel tank and armament in wings N.B. Henley flew with Vulture. Problem is the radiator would be a big scoop for water if the plane had to ditch. Perhaps not the safety standards required of a plane that could have flown before WW2. Or maybe a Sea Defiant, turret replaced with fuel tank, armament in wings, arrestor hook, upwards wing folding, optional catapult attachments. Early version Spitfires I/II/Va/b, definitely not, its too fragile.


Henley with Vulture engine






Please note that many large, 2/3 seat aircraft were used for engine test beds because they had the room for extra engine instruments and room for one or more test engineers to monitor the engine and not be bothered flying the plane. Few, if any, carried any armament or other combat equipment. No mention is ever made of any ballast being carried to get the CG in proper position for safe flying as few dozen or few hundred pounds of ballast in the tail was of little importance. The idea being to get a number of hours on the engine in an environment different from the test stand in the test house to see if any unforeseen problems came up. 

I have to wonder why so many people want to use the Defiant as a basis for some other type or mission aircraft.
You can't put a fuel tank where the turret was,




it is too far behind the CG. You could put the fuel tank where the pilot is and then move the pilot to where the turret was for a truly dismal forward view.
The plane only had a 250sq ft wing, in between a Spit and a Hurricane and had a gross weight roughly 2000lbs heavier, take off and landing speeds would be higher than either one and no, the turret was NOT responsible for ALL the extra weight, at least not directly. If you yank the turret from an existing airframe you save around 600lbs and since there is no longer a gunner you save another 200lbs (depending on how well fed he was, the 200lbs includes his parachute and his personal dinghy). A lot of the "extra" weight was the heavier structure needed to support the weight of the turret or to meet the load standards for the heavier gross weight. You could lighten up the structure but that means redoing the stress/strength calculations for every part of the airframe.
Just design a new airplane to begin with, you aren't saving much.


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## Kevin J (May 12, 2019)

wuzak said:


> Since the land plane version of the Hurricane II couldn't do that, it would be very doubtful that a Sea Hurricane could.
> 
> 
> 
> ...



The Sea Hurricane IIc did 342 mph which was 6 mph faster than the Hurricane IIc.

Yes, the Vulture went out of production, but its problems were no worse than the Sabre. Perhaps if the Vulture had a service to champion it. Frankly, I wouldn't go for it though as its ditching characteristics would be awful.

I've never seen any proposal for a new wing on the early Spitfire. Only the proposal that the wings be folded back.


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## Kevin J (May 12, 2019)

Shortround6 said:


> Henley with Vulture engine
> View attachment 537910
> 
> 
> ...


IIRC the turret including gunner was 600 lbs which was at the c.g. of the aircraft.


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## Kevin J (May 12, 2019)

IIRC, the primary pre-war requirements for the FAA were loiter endurance, all weather capability, and the speed necessary to intercept recce and patrol aircraft. Hence the Fulmar. However once the FAA was operating in contested waters and opposed by the Me 110, they needed something faster. The Hurricane Ib/1c with 12/16 lbs boost satisfied that need. The Seafire must have been disappointing when it eventually arrived. In WW2 in order of aircraft destroyed it was the Fulmar, Sea Hurricane then Seafire in that order. So the Admiralty must have got it right.


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## XBe02Drvr (May 12, 2019)

Kevin J said:


> IIRC the turret including gunner was 600 lbs which was at the c.g. of the aircraft.


That doesn't make sense. Look at the drawing SR6 provided. A CG aft of the trailing edge of the wing would make for an unflyable aircraft with divergent negative stability. And we all thought the Airacobra was bad!
Cheers,
Wes

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## Shortround6 (May 12, 2019)

Kevin J said:


> IIRC the turret including gunner was 600 lbs which was at the c.g. of the aircraft.



If the turret was at the CG it is the only airplane in history to fly with the CG in line with trailing edge of the wing (or aft of it). This is for planes with one wing. 

If you are right about the weight of the turret that just makes trying to convert a Defiant worse as pulling 600lbs instead of 800lbs means the basic airframe is that much heavier.

BTW the Prototype Hurricane MK II P.3269 (eight guns) was tested at 340mph at 20,000ft using 50.67in of absolute boost and 3020rpm. Not sure of the exhaust set up as the plane was being used to figure out/check on exhaust thrust calculations. Using 48.24in at 20,000ft the speed was 335mph. 

The calculated hp to the prop was 1126hp in the first case and 1073hp in the 2nd, with 126.8hp (not pounds of thrust) added by the exhaust in the first case and 113hp in the 2nd case. 

RR and Hawkers had both done calculations and Hawkers did the test flying and the calculations were in close agreement (but not identical ) and were close to the test flying results.


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## XBe02Drvr (May 12, 2019)

Shortround6 said:


> If the turret was at the CG it is the only airplane in history to fly with the CG in line with trailing edge of the wing (or aft of it).


There may have been others, but if there were, their flights were very brief and very terminal.
Cheers,
Wes


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## XBe02Drvr (May 12, 2019)

Shortround6 said:


> If the turret was at the CG it is the only airplane in history to fly with the CG in line with trailing edge of the wing (or aft of it).


Actually there was one historically. In 1912, Harriet Quimby was flying a Bleriot monoplane with a lifting tail and the CG aft of the wing, when it abruptly diverged, pitching down so sharply that it threw her and her passenger right out of the cockpit and into Boston harbor. Definitely terminal. Every lesson in the sky has been paid for in blood.
Cheers,
Wes

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## Kevin J (May 12, 2019)

Shortround6 said:


> If the turret was at the CG it is the only airplane in history to fly with the CG in line with trailing edge of the wing (or aft of it). This is for planes with one wing.
> 
> If you are right about the weight of the turret that just makes trying to convert a Defiant worse as pulling 600lbs instead of 800lbs means the basic airframe is that much heavier.
> 
> ...


AFAIK the Hurricane I did about 335 mph at 7000 feet with 16 lbs boost, the Sea Hurricane Ib, 20 mph less but only 308 mph at altitude. Both speeds being pretty good considering that you want the speed at low altitudes to protect your ships. The Hurricane I could out dive the Zero and was faster low down. Against an Me 110, which was much faster all round, I believe it all depended on the skill of the pilots involved, against the Zero, they would have needed the Thach weave to be effective.


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## pinsog (May 12, 2019)

Why not a turbocharged F4F-3?

Original 2 speed 2 stage P&W R-1830-76: 
1200 hp for takeoff 
1100 hp from SL-2500 feet
1050 hp from 4800-11000 feet
1000 hp from 12200-19000 feet

with a P&W R-1830-47 with a turbocharger (same engine as the P43 Lancer) 
1200 hp from SL-25000 feet 

SL speed increases from 278 to 286
Speed at 5500 goes from 295 to 308
Speed at 13000 goes from 313 to 332
Speed at 19000 goes from 330 to 350
Speed at 22000 goes from 326 to 351

The F4F-3 speed numbers above included 150 pounds of armor and a self sealing fuel tank.

Drag should be identical, F4F-3 already has an intercooler so just plumb turbo into existing intercooler. I believe the weight would remain nearly the same as the weight of the turbo, 135 pounds, would be offset by the lighter single speed single stage engine that goes with it. I believe the best place for the turbo would likely be where it was on the P43 Lancer, but the pipe/plumbing would probably needed to have been done in the original prototype, not sure if there was room for the exhaust pipe and return pipe to be retrofitted later.
I also believe climb would be substantially improved as well as you would gain 100 hp down low, 200 hp from 12200-19000. 

At 25000 feet HP jumps from 860 to 1200. 

Performance virtually equal with the Spitfire mkII at 5000 feet and surpasses it above 20,000 and should continue to increase with altitude. (I can't find any speed data on the F4F-3 above 22000 feet)


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## Shortround6 (May 12, 2019)

XBe02Drvr said:


> Actually there was one historically. In 1912, Harriet Quimby was flying a Bleriot monoplane with a lifting tail and the CG aft of the wing, when it abruptly diverged, pitching down so sharply that it threw her and her passenger right out of the cockpit and into Boston harbor. Definitely terminal. Every lesson in the sky has been paid for in blood.
> Cheers,
> Wes


 Well I did add this sentence after I first wrote it "This is for planes with *one* wing " 

So we wouldn't get into things like.




or 









Once you start using a secondary lifting surface then all bets are off on CG location (except it has to be between the two lifting surfaces and about where the balance of lift (?) would be. 

The vast majority of aircraft (non swept wing jets, etc) flew with the CG somewhere in the high 20% of cord range. Say 27-30%? some may have exceeded that slightly.

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## Kevin J (May 12, 2019)

pinsog said:


> Why not a turbocharged F4F-3?
> 
> Original 2 speed 2 stage P&W R-1830-76:
> 1200 hp for takeoff
> ...



I can't see the point of a turbo in a Wildcat, after all you're not going to be intercepting bombers at that altitude, you need low altitude performance. The turbo and ducting is going to add weight and unnecessary complexity to the Wildcat. Manoeuvrability was bad enough as it was. Lets take off say 12 mph from your figures as per F4F-4 to account for that turbo and you're slower and less manoeuvrable at the altitudes where most of the fighting is going to take place. No, definitely not. As an interceptor I'd still prefer the Hurricane Ib/Ic in 1941/42 as it has its best performance low down where you need it followed by the Sea Hurricane IIb/c in 1942, then the Seafire LIIc in early 1943. As for the Seafire Ib use it primarily for training in 1941/42, the Seafire IIc, evaluation only in 1942/43. If you want a patrol and recce fighter then the Dauntless or the Fulmar, an escort / air superiority fighter then it must be the Wildcat as it has the best range and a reasonable performance. 

I'm not even going to suggest the Miles M 20/2 as although it had good range, armament and performance, its made of wood and that's not going to last very long at sea. My Sea Defiant has already been knocked back as an idea. As an idea of what Boulton Paul could have done, have a look at the (Sea) Balliol which first flew in 1947 and had a service intro of 1950. What a crappy performance as a fighter this would have had, worse than a Sea Hurricane Ib/c.

Boulton Paul Balliol - Wikipedia


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## pinsog (May 12, 2019)

Kevin J said:


> I can't see the point of a turbo in a Wildcat, after all you're not going to be intercepting bombers at that altitude, you need low altitude performance. The turbo and ducting is going to add weight and unnecessary complexity to the Wildcat. Manoeuvrability was bad enough as it was. Lets take off say 12 mph from your figures as per F4F-4 to account for that turbo and you're slower and less manoeuvrable at the altitudes where most of the fighting is going to take place. No, definitely not. As an interceptor I'd still prefer the Hurricane Ib/Ic in 1941/42 as it has its best performance low down where you need it followed by the Sea Hurricane IIb/c in 1942, then the Seafire LIIc in early 1943. As for the Seafire Ib use it primarily for training in 1941/42, the Seafire IIc, evaluation only in 1942/43. If you want a patrol and recce fighter then the Dauntless or the Fulmar, an escort / air superiority fighter then it must be the Wildcat as it has the best range and a reasonable performance.



If you remove the 2 speed 2 stage engine from an F4F-3 and replace it with a single stage single speed engine you lose about 80 pounds. A B1 turbo weighs about 135 pounds. Not sure how much a couple of 12 foot long, 5 inch diameter sheet metal tubes weigh, but it isn't very much. The F4F-3 already has an intercooler for the 2 speed 2 stage engine we just removed, so we just use it for the turbo now. Lets say we gain 100 pounds.
To offset that 100 pound weight gain we now have: 1200 hp from SL-25000 feet,
that is 100 more hp from SL-2500 feet
150 more hp from 4800-11000 feet
200 more hp from 12200-19000 feet
340 more hp at 25000 feet

Where does more drag come in? the F4F-3 already had an intercooler which we still use with the turbo

F4F-3 was a bad maneuvering plane? An F4F-4 will turn inside of a Spitfire according to the Royal Navy. Compared to a Zero, anything turned bad at slow speeds except maybe a Gladiator.

Wildcats at Guadalcanal often fought, or at least started their fights at close to 30,000 feet. Took them about 40 minutes to get there. I imagine those guys would have welcomed a turbocharged Wildcat.


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## pinsog (May 12, 2019)

If drag remained the same and since we are using the intercooler that the Wildcat already had I can't see why drag would increase, here are the speed increases according to the cube formula:

SL speed increases from 278 to 286 (increase of 100 hp from 1100 to 1200)
Speed at 5500 goes from 295 to 308 (increase of 150 hp from 1050 to 1200)
Speed at 13000 goes from 313 to 332 (increase of 200 hp from 1000 to 1200)
Speed at 19000 goes from 330 to 350 (increase of 200 hp from 1000 to 1200)
Speed at 22000 goes from 326 to 351 (increase of 240 hp from 960 to 1200)


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## Kevin J (May 12, 2019)

pinsog said:


> If drag remained the same and since we are using the intercooler that the Wildcat already had I can't see why drag would increase, here are the speed increases according to the cube formula:
> 
> SL speed increases from 278 to 286 (increase of 100 hp from 1100 to 1200)
> Speed at 5500 goes from 295 to 308 (increase of 150 hp from 1050 to 1200)
> ...


First, you're looking at 330 mph without self sealing fuel tanks. Second, the F4F-4 with folding wings and six guns, the performance goes down to 318 mph. So added weight and guns decreases performance to 318 mph. Are you saying that the turbo and ducting is not going to decrease speed at low altitude? I agree that it will increase at high altitude, but most combat will be lower down. I think your figures are over optimistic.


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## pinsog (May 12, 2019)

Kevin J said:


> First, you're looking at 330 mph without self sealing fuel tanks. Second, the F4F-4 with folding wings and six guns, the performance goes down to 318 mph. So added weight and guns decreases performance to 318 mph. Are you saying that the turbo and ducting is not going to decrease speed at low altitude? I agree that it will increase at high altitude, but most combat will be lower down. I think your figures are over optimistic.




http://www.wwiiaircraftperformance.org/f4f/f4f-3-detail-specification.pdf

There is the link to the F4F-3 test. The screen shot is from the middle of the test, if you look close it gives the weight of the armor and the self sealing fuel tank

Did you look at the figures I provided above? The ducting and the turbo are inside the airplane and might add 100 pounds. In exchange for that extra 100 pounds you get the extra horsepower at the levels I showed.

SL speed increases from 278 to 286 (increase of 100 hp from 1100 to 1200)
Speed at 5500 goes from 295 to 308 (increase of 150 hp from 1050 to 1200)
Speed at 13000 goes from 313 to 332 (increase of 200 hp from 1000 to 1200)
Speed at 19000 goes from 330 to 350 (increase of 200 hp from 1000 to 1200)
Speed at 22000 goes from 326 to 351 (increase of 240 hp from 960 to 1200)

Why wouldn't it be faster if it has an extra 100 hp, 150 hp or 200 hp? We are using the existing intercooler so where would extra drag come from?


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## Kevin J (May 12, 2019)

pinsog said:


> http://www.wwiiaircraftperformance.org/f4f/f4f-3-detail-specification.pdf
> 
> There is the link to the F4F-3 test. The screen shot is from the middle of the test, if you look close it gives the weight of the armor and the self sealing fuel tank
> 
> ...


Was it ever tried?


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## Shortround6 (May 12, 2019)

pinsog said:


> Drag should be identical, F4F-3 already has an intercooler so just plumb turbo into existing intercooler





pinsog said:


> At 25000 feet HP jumps from 860 to 1200



The intercooler will be too small.

Look at your own figures. at 25,000ft you are trying to cool more intake air mass, yes the two stage engine is using up extra power made in the cylinders to power the supercharger but not 240hp worth.

Then you have the problem of the mass of air needed to do the cooling. the air at 25,000ft is about 90% of weight /mass of the air at 22,000ft per cubic ft so you need that 10% or so more cooling flow just to handle the power level you had at 22,00ft. _BUT_ since the air is thinner you need to compress it more which means it is hotter and you are trying to compress more of it to get your 1200hp at 25,000 so there are 3 reasons why the original intercooler will not work, or will limit power much like the intercooler on the P-38G &H. 

B-24 engine nacelle 




scoop on one side was for both the engine intake air and the oil cooler, scoop on the other side was for the intercooler. Granted the F4F stuck the oil cooler out under the wing. 

I believe there is a photo of a B-24 under construction showing the size of the intercooler in one of the threads we have on improved F4Fs.

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## pinsog (May 12, 2019)

I think tomo park said they built a prototype called the XF4F-5, but I don't know anything about it.


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## pinsog (May 12, 2019)

Short round, I was hoping you might show up. Do you know how they were able to keep it cool in the P43? Same engine, similar sized planes. 
Also, I do realize that the hypothetical turbocharged F4F-3 would not be able to run around at 1200 hp all the time. The P43 used 1100 hp as max continuous and 1200 hp would be more of a 'war emergency' type setting, I believe 5 minute max on the P43


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## Shortround6 (May 12, 2019)

From post 68 in this thread

Forums / USAAF / USN Library / Republic P-43 Lancer - Axis and Allies Paintworks 

It has some interior pictures of the P-43 which, while showing camera installations for photo recon work also show some of the air ducts inside the fuselage, in addition to the exhaust pipe and turbo outside.


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## pinsog (May 12, 2019)

I saw those. Do you think the routing of the pipe exposed in the belly of the P43 was done as maybe a ‘poor mans intercooler’? Is that the pipe from the engine to the turbo or from the turbo to the engine?


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## Shortround6 (May 12, 2019)

The exposed pipe is the exhaust pipe leading to the exhaust turbine. 

This was sort of a poor mans exhaust cooler to keep from overheating the turbine blades (at least that is my opinion, the B-17, B-24 and P-38 all used a greater or lesser amount of exposed exhaust pipe before the turbo for some reason. early P-38s (and other planes?) had pieces of armor plate between the Turbo and occupied areas of the plane to prevent thrown blades from injuring the pilot/crew. The P-47 used the longest pipes of any production turbo installation and was the ony production plane to hide the turbo inside the plane instead of hanging it out in the airstream 

The intake charge air and intercooler air are in ducts/pipes much like the ones used on the P-47.


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## pinsog (May 12, 2019)

I thought it was the exhaust pipe driving the turbine and I also agree that they were trying to cool it as much as possible and the exposed pipe was probably as easy/cheap/power free way of doing it as they could come up with. 

When did they get the turbocharger controls/regulator perfected? I know they had issues at least through 1941. 

Can you give your best guess on weight difference between a regular F4F-3 and hypothetical turbocharged F4F-3? B1 turbo weighed 135 pounds. Single stage single speed engine would be lighter. A 5 inch diameter tube from engine to turbo, another from turbo to engine. I guessed maybe 100 pounds heavier for turbocharged F4F-3


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## Shortround6 (May 12, 2019)

You have duct bringing the intake air from teh bottom of the cowl to the turbo (long), then the pipe bringing the air from the turbo to the intercooler (short) then the pipe bringing the air from the intercooler to the carb on the engine (long) and on the P-43 a pipe/duct bringing the cooling air for the intercooler from the bottom of the cowl to the rear fuselage. 

The P-43 used a 364lb Curtiss Electric propeller that was 11ft in diameter, the F4F-3 used a 312lb propeller that was 9ft 9in in diameter. Now perhaps the Hamilton standard props were lighter than the Curtiss Electrics but I doubt you are going to get an 11ft prop for 312lbs. You also don't want to try to put your 1200hp into the thin air at 25,000ft with a 9ft 9in prop. 

Most of the P-43 engines went 1473lbs vrs the 1540-1560lbs of the -86 engine in most of the F4F-3s and 4s. 
I have no idea on the weight of the intercoolers for either plane. 
You also need brackets/supports for the turbo, the intercooler and the piping. at 25,000ft you are running almost triple the pressure in the intake ducts after the turbo as the ambient air. call it 9lbs per square inch over how many sq ft of duct wall? 

What kind of brackets/supports do you want for that 135lb turbo charger when the plane does a 6 G pullout from a dive? or does a 5-6 G turn in combat for a few seconds? 
Actually the installation was supposed withstand 12 Gs ultimate like the rest of the plane. 

Please note that the engine weights do not include starters or generators or hydraulic/oil pump for propeller control. Or a few other accessory pumps. If you have an electric propeller you might want a bigger generator than a plane with a hydraulic propeller. In any case the Hydraulic propeller doesn't use the plane hydraulic system.


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## XBe02Drvr (May 13, 2019)

Shortround6 said:


> Well I did add this sentence after I first wrote it "This is for planes with *one* wing "
> 
> So we wouldn't get into things like.
> View attachment 538005
> ...


Those abortions you pictured wouldn't be much of an improvement on Harriet's Bleriot. If you want to have a "lifting" tail, the only practical way to do it is a canard, a la Vari-eze, Starship, Ascender, or Shinden. Lifting tails aft of the main wing tend to have negative stability. Any increase in airspeed causes a pitch down; not a desirable behaviour. Various mechanisms have been devised over the years to reverse this tendency, but they generally entail weight and drag that defeats the performance gain sought by eliminating negative lift at the tail. FBW to the rescue!
Cheers,
Wes

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## MycroftHolmes (May 13, 2019)

I believe that in Shores' _Malta: The Hurricane Years_ it mentions that the engineering staff on Malta converted a Hurricane into a LR recce aircraft, with extra fuel-tanks and a larger oil-tank in one wing, and this aircraft did 350 mph. If this could be done with the limited resources available in Malta, I imagine that a proper conversion would exceed this figure. Fit a bulged canopy, modify the exhaust-stubs, replace the mast antenna with a whip-type, fit less-draggy fairings on the guns and clip the wings. Similar modifications increased the top speed of the Typhoon from about 395 mph to over 415 mph, so I think it would be pretty simple to get an extra 15-16 mph on a Hurricane. Armament would be 2 x 20mm with 100-120 rpg, and extra fuel could be carried in the space thus freed-up.

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## pinsog (May 13, 2019)

Thank you Shortround. Let me ask you this: I understand thin air turbocharger heat problems and needing a larger intercooler at say 25,000 feet.

Would the standard F4F-3 intercooler be enough for the turbocharged engine as long as the turbocharged engine doesn't exceed the hp of the 2 speed 2 stage engine? Or does the turbocharger heat the air more for the same output?

For instance, if the standard F4F-3 is at 2500 feet at 1100 hp and our mythical turbocharged F4F-3T is right beside it at 1100 hp, would the standard intercooler be enough to cool the turbocharged intake air?

What if they were both at 13,000 feet at 1000 hp? Or 19,000 feet at 1000 hp?


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## XBe02Drvr (May 13, 2019)

pinsog said:


> For instance, if the standard F4F-3 is at 2500 feet at 1100 hp and our mythical turbocharged F4F-3T is right beside it at 1100 hp, would the standard intercooler be enough to cool the turbocharged intake air?
> 
> What if they were both at 13,000 feet at 1000 hp? Or 19,000 feet at 1000 hp?


What's the use? If you're just going to match horsepower, why mess around with a turbo? Or are you just trying to get a feel for relative intercooler effiencies? Any way you slice it, an intercooler to handle the greater heat of compression in the thinner air is going to be draggier and heavier than the stock item in the original Wildcat. Will the extra horsepower at altitude be enough to give a performance advantage despite the increased weight and drag? Stay tuned for tomorrow's episode!
Cheers,
Wes


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## pinsog (May 13, 2019)

I’m getting a feel for intercooler efficiencies.

We are talking about increasing power from 12,200-19,000 by 20% (going from 1000 hp to 1200 hp). That is a substantial increase in power. If the original intercooler handles the same power at the same altitudes, then maybe you only use the increased power for War Emergency Boost. I'm sure they would test larger intercoolers and weigh out drag vs increased power.

The P47 had low altitude issues because they had to build an enormous body to squeeze a turbocharger into. My thoughts are, putting a turbo into an already chubby design where it should already fit. In other words, I'm not turning a sleek Corsair into a Thunderbolt to fit a turbocharger, I'm taking a non turbo Thunderbolt and adding a turbo.

As far as weight, your gaining 50 pounds for a prop and 135 for a turbo plus some ducting. controls, mounts etc. Subtract 65 to 90 pounds for the lighter engine. Weight doesn't bother me as much as drag. We all know that the top speed on Mustangs etc didn't change much with added weight, it was the climb it effected.

If we add a bigger intercooler so we can use more power at all altitudes, that should be the only increase in drag. So I would think that the increase in drag would not be equal to 100 extra hp at low altitude.

How much hp to overcome a larger intercooler? I don't know, that is why I am asking.

"Would the extra HP be enough to give a performance advantage despite increased weight and drag?" I would think so, by a large margin at altitude. How many people would want to fight in a non turbo P38 or P47 for the weight advantage of ditching the turbo and related equipment?


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## fliger747 (May 15, 2019)

Just a comment on two stage supercharger power draws. An R2800, capable of 2000 hp in neutral blower at SL could only make 1600 HP in high blower at optimal altitude. The blower took an amazing 400HP! So 250 or so for a smaller engine might be a reasonable power draw for two stage blower at altitude.

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## Barrett (May 16, 2019)

The X-job Hellcat first flew with the Wright R2600 which presumably would've been the production mill had the P&W been unavailable. Perish-forbid, but it still woulda been superior to the F4F-4...


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## pinsog (May 17, 2019)

Referring to drag on the hypothetical F4F-3 with a turbocharger.
This is about the only thing I could find to make a comparison. The FM2 went from a 48 inch diameter P&W 1830 to a 55 inch diameter Wright 1820, one would think that would be a huge increase in drag, BUT, look at the 1200 hp normal rating for the FM2 on the graph.
Top speed at normal rating of 1200 hp (same as the turbocharged F4F-3 would have) went from 278 to 292 at SL, from 295 to 308 at 5500 feet. About a 15 mph increase with a 55 inch diameter engine instead of a 48 inch diameter engine.
If you continue the 1200 hp speed on the graph in a straight line all the way up to 25,000 feet, like it had a turbocharger instead of the single stage Wright, the top speed would hit 350 at 20,000 feet just like the calculations showed, and would, I assume continue to gain speed up to 25,000 feet where the turbocharger was rated.

The other question I would have, which could only be known by actual testing is which would be better, a lighter weight but larger diameter turbocharged Wright 1820 for better climb. Or a heavier but smaller diameter P&W 1830 that would probably be faster and have better over the nose visibility.

That extra increase in top speed of between 10 mph at SL up for over 20 mph at altitude and the substantial increase in climb rate would sure be nice when tackling a Zero, giving the pilots a decent platform for boom and zoom early in the war until the Hellcat arrived

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## Shortround6 (May 17, 2019)

The FM-2 didn't have an intercooler and the frontal area/diameter of the respective engines was not governing factor in the frontal area of the fuselage and even on the Hawk 75 where it was, the cowlings minimised the difference.


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## pinsog (May 17, 2019)

Above 12,000 feet the turbocharged Wildcat would gain 200 hp over the original. Would a 20% increase in power not overcome the drag of an intercooler? At 25,000 feet is a 43% increase in power


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## pinsog (May 17, 2019)

Question: If the increased diameter of the 1820 is not a factor on a Wildcat, then why would an intercooler be a factor if its less share footage than the increased diameter? (48 inch diameter plus intercooler vs 55 inch diameter)

I'm not arguing as much as trying to get my head around this


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## Shortround6 (May 17, 2019)

You are going to get better performance than the original engine, the question is it enough to get you to 350mph?

Here is a picture of a B-24 intercooler from another thread. 





It is the silver finned box visible through the engine mount. 

A general rule of thumb was that a 2nd stage supercharger and intercooler cost around 30mph below 15,000ft. 

It depends on how tidy you can make the installation. In the above photo the duct above the brass oil cooler is the carburetor inlet. Note size difference (required air flow?) between it and the intercooler. 

Another photo showing a B=24 intercooler.





Yes you could split the intercooler into two units for packaging but you are going to need pretty close to that volume of intercooler and those size ducts to handle the airflow. 
Note size in relation to the R-1830 engine. 

There was one very untidied mock up of a turbo and intercooler on a P-39 that cost 40mph at low altitude. Not the original. 

You may get 340-350mph at 25,000ft, are you willing to give up even 20mph at lower altitudes to get it?

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## pinsog (May 17, 2019)

Is a bomber intercooler larger than a fighter intercooler since it has to work at lower speeds? (Im picturing the difference between a heavy 4WD truck pulling a trailer and a sports car with the same engine

Where was that gigantic intercooler mounted on a P43?


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## Shortround6 (May 17, 2019)

It was mounted in the rear of the plane. A lot of the drag has to do with the air flowing through the ducts and the intercooler "core" and not necessarily the increase in frontal area. 

The idea of the truck vs Sports car only works so far. the intercooler is only cooling the incoming air, not the engine, incoming air gets too hot and the mixture detonates in the engine, wrecking it. A
And most fighters had a best climb speed of under 200mph IAS so they aren't climbing at a speed (horizontal speed) that much faster than the bombers.


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## Kevin J (May 17, 2019)

pinsog said:


> View attachment 538477
> 
> Referring to drag on the hypothetical F4F-3 with a turbocharger.
> This is about the only thing I could find to make a comparison. The FM2 went from a 48 inch diameter P&W 1830 to a 55 inch diameter Wright 1820, one would think that would be a huge increase in drag, BUT, look at the 1200 hp normal rating for the FM2 on the graph.
> ...


Surely you're looking for low altitude performance only to combat incoming Jap attack aircraft maybe even Kamikaze. The turbo is unnecessary.


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## pinsog (May 17, 2019)

"a general rule of thumb was that a 2nd stage supercharger and intercooler cost 30 mph below 15,000 feet" 

I very much appreciate your knowledge on these subjects and have learned a lot from you over the years, but you understand that I have a hard time believing that unbolting the turbocharger and removing the intercooler from a P47 Thundebolt, P38 Lightning or P43 Lancer without reducing the size of the airframe could increase top speed by 30 mph below 15,000 feet. That is why Im having trouble seeing an F4F-3 lose much speed by adding a turbocharger since the aircraft doesn't have to get bigger to fit it, its all internal. 

Do you see my confusion?

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## XBe02Drvr (May 17, 2019)

pinsog said:


> This is about the only thing I could find to make a comparison. The FM2 went from a 48 inch diameter P&W 1830 to a 55 inch diameter Wright 1820, one would think that would be a huge increase in drag, BUT, look at the 1200 hp normal rating for the FM2 on the graph.


What a mere comparison of engine diameters fails to address is internal cooling drag. The ducting that forces the airflow to hug the cylinder fins on the single row 1820 is relatively simple and straightforward. The double row 1830, OTOH, faces the tricky proposition of keeping the rear cylinders cool, making the airflow path twisty and torturous, and generating extra drag. Pratt and the airframe builders got better at this as time went on, but never approached the low drag simplicity of Wright's 1820.
My engines instructor at mech school had been an 8th AF mechanic, first on Mustangs, then on the heavies. As part of a troubleshooting crew, his group helped out B17 and B24 squadrons dealing with particularly thorny maintenance issues. He said that under the cowling, a B24's engine installation was a plumber's nightmare, with induction, intercooler, exhaust, and cooling air ducting going every which way. It's the drag you don't see that gets you.
Cheers,
Wes

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## pinsog (May 17, 2019)

XBe02Drvr said:


> What a mere comparison of engine diameters fails to address is internal cooling drag. The ducting that forces the airflow to hug the cylinder fins on the single row 1820 is relatively simple and straightforward. The double row 1830, OTOH, faces the tricky proposition of keeping the rear cylinders cool, making the airflow path twisty and torturous, and generating extra drag. Pratt and the airframe builders got better at this as time went on, but never approached the low drag simplicity of Wright's 1820.
> My engines instructor at mech school had been an 8th AF mechanic, first on Mustangs, then on the heavies. As part of a troubleshooting crew, his group helped out B17 and B24 squadrons dealing with particularly thorny maintenance issues. He said that under the cowling, a B24's engine installation was a plumber's nightmare, with induction, intercooler, exhaust, and cooling air ducting going every which way. It's the drag you don't see that gets you.
> Cheers,
> Wes



It does make the single row 1820 setup on the B17 make sense


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## pinsog (May 17, 2019)

Maybe others can learn from my questions and all your detailed explanations. Not just arguing to argue. A lot of this makes sense but not all of it


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## Shortround6 (May 17, 2019)

pinsog said:


> "a general rule of thumb was that a 2nd stage supercharger and intercooler cost 30 mph below 15,000 feet"
> 
> I very much appreciate your knowledge on these subjects and have learned a lot from you over the years, but you understand that I have a hard time believing that unbolting the turbocharger and removing the intercooler from a P47 Thundebolt, P38 Lightning or P43 Lancer without reducing the size of the airframe could increase top speed by 30 mph below 15,000 feet. That is why Im having trouble seeing an F4F-3 lose much speed by adding a turbocharger since the aircraft doesn't have to get bigger to fit it, its all internal.
> 
> Do you see my confusion?


 You are part right, once you have sized the airplane to hold all that stuff, just taking it out won't magically get you 30mph.
But as 
X
 XBe02Drvr
has said, there is a lot of internal drag associated with the installation.
How much rearranging of the internals of an F4F-3/4 you are going to have to do is also subject to question or interpretation.
On the F4F-3/4 the intercoolers were in front of the wheel wells and exhausted into them. The wheel wells and retracting mechanism take up a fair amount of the fuselage behind the engine. There is a 117 gallon fuel tank under the pilots seat but it is narrow enough to allow the pilot to look down past it and out through a small window (or 2?) on each side. How useful this was I have no idea. there was a 27 gallon or larger reserve tank behind the cockpit but low in the fuselage. radio equipment took up some of the space in the rear of the plane 

The P-43 is supposed to have carried it's fuel in the wing/s in integral tanks (which leaked) I have no idea if they were one foot apart or several feet apart were the exhaust pipe ran along the belly of the plane. 

Photo of P-35 refueling.





Not saying you can't run the exhaust pipe underneath the fuel tank/s in the Wildcat but it may require smaller tanks or another tank added someplace else? 

Just about every American turbo (P-47 excepted) was mounted a number of feet from the engine and with an exposed exhaust pipe. Speculating it was to reduce the temperature of the exhaust gases before they reached the turbo. Routing the exhaust pipe past/through the landing gear and fuel tanks may not be insurmountable but harder than on the P-43. Getting cooling air for rear mounted intercooler and getting the air back to the engine may require a lot of stuff to be relocated. 

Take a look at a cutaway of the wildcat. there really wasn't a lot of empty space in in the fuselage. 

P-43 had both the fuel and the landing gear in the wings.


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## pinsog (May 18, 2019)

Kevin J said:


> Surely you're looking for low altitude performance only to combat incoming Jap attack aircraft maybe even Kamikaze. The turbo is unnecessary.



I missed your post. I agree that attacks in carriers weren’t ‘high altitude’ as such, but divenombers might approach above 12,000 feet with Zero’s above that. The turbocharger would give 200 more hp at 12,200 feet than the F4F-3 had in real life, 1200 hp vs 1000. (100 hp extra SL-5500, 150 hp extra from 5500-12,200, 200 hp extra from 12,200-19,000, 340 hp extra at 25,000) Also vastly increase climb rate at all altitudes.

The real question is at what level does extra hp overcome drag? How much extra drag would there be? Etc

I tend to lean toward 100 extra hp at SL would overcome extra drag and top speed would at least remain the same. One or 2 very knowledgeable people are at least questioning that idea if not completely disagreeing. I hope my questions can help them explain to all of us what their theories are so we can all benefit


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## Kevin J (May 18, 2019)

pinsog said:


> I missed your post. I agree that attacks in carriers weren’t ‘high altitude’ as such, but divenombers might approach above 12,000 feet with Zero’s above that. The turbocharger would give 200 more hp at 12,200 feet than the F4F-3 had in real life, 1200 hp vs 1000. (100 hp extra SL-5500, 150 hp extra from 5500-12,200, 200 hp extra from 12,200-19,000, 340 hp extra at 25,000) Also vastly increase climb rate at all altitudes.
> 
> The real question is at what level does extra hp overcome drag? How much extra drag would there be? Etc
> 
> I tend to lean toward 100 extra hp at SL would overcome extra drag and top speed would at least remain the same. One or 2 very knowledgeable people are at least questioning that idea if not completely disagreeing. I hope my questions can help them explain to all of us what their theories are so we can all benefit


Compare the single stage XP-41 (323 mph) and turbo Lancer (356 mph) the single stage F4F-3A (312 mph), the two stage F4F-3 (331mph). The Vultee Vanguard with a single stage engine did 340 mph at 20000 feet, 358 with the two stage engine of which very few were available in 1941. By Pearl Harbour only one carrier had Wildcats. As I see it, the best you'll get out of a turbo Wildcat at altitude is 343 mph which is 12 mph more than the F4F-3 at an altitude that is not required and with added complexity.


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## pinsog (May 18, 2019)

Kevin J said:


> Compare the single stage XP-41 (323 mph) and turbo Lancer (356 mph) the single stage F4F-3A (312 mph), the two stage F4F-3 (331mph). The Vultee Vanguard with a single stage engine did 340 mph at 20000 feet, 358 with the two stage engine of which very few were available in 1941. By Pearl Harbour only one carrier had Wildcats. As I see it, the best you'll get out of a turbo Wildcat at altitude is 343 mph which is 12 mph more than the F4F-3 at an altitude that is not required and with added complexity.



I brought up the P66 Vanguard once and they pointed out it was a much smaller aircraft than the Wildcat or the P36. 

The XP-41 vs P43 Lancer is a great example, The F4F-3A vs F4F-3 is another great example. 

I’m showing turbocharged Wildcat at more like 350+ at 19,000 feet. 10 mph faster down low (all depending on increased drag). I guess whether 20 mph extra is worth it depends on if your 10 mph faster or 10 mph slower than the pursuing Zero. You’ll also gain quite a bit of climb over the whole range. 

You gain some complexity with the turbo, but you gain complexity with a Hellcat and Corsair as well. A bit of complexity along with 20 mph extra might keep you from getting killed


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## pinsog (May 18, 2019)

Does anyone have any data on the XP-41? That might be a good way to compare single stage vs turbocharged engines at SL-10,000 feet in the same airframe.


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## pinsog (May 18, 2019)

Shortround and Xbe02Drvr, I’ll be back later to pick your brains. Going to be busy most of the day. 

Shortround, I agree with your ‘shifting stuff around to fit turbo inside F4F-3’. I said back on page 6 or 7 that this would have needed to be done probably on the prototype, although I feel pretty sure it would fit, if done at the beginning. 

Please think about this, would a P47 gain any speed at SL if turbo and intercooler were removed and air intake for turbo and intercooler were removed?


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## Reluctant Poster (May 18, 2019)

pinsog said:


> I thought it was the exhaust pipe driving the turbine and I also agree that they were trying to cool it as much as possible and the exposed pipe was probably as easy/cheap/power free way of doing it as they could come up with.[/QUO
> 
> 
> The exposed pipe may have been cheap and easy but it can't have been very effective. The surface area is too small to have an appreciable cooling effect. Look at a your car radiator and calculate the surface area of all those fins. In addition it must have had a disastrous effect on the aerodynamics. The P-47 installation is much better aerodynamically it wasn't just moved inside for aesthetics. The typical American practice of hanging the turbocharger in breeze was not a good idea. It may not have been too critical for bombers cruising at 160 mph but for fighters it would affect performance.
> The other thing to note is that turbulent flow is what you want for heat transfer but not what you want for drag. I've always been surprised that the leading edge intercooler of the P-38 worked at all.


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## Shortround6 (May 18, 2019)

Kevin J said:


> Compare the single stage XP-41 (323 mph) and turbo Lancer (356 mph) the single stage F4F-3A (312 mph), the two stage F4F-3 (331mph). The Vultee Vanguard with a single stage engine did 340 mph at 20000 feet, 358 with the two stage engine of which very few were available in 1941. By Pearl Harbour only one carrier had Wildcats. As I see it, the best you'll get out of a turbo Wildcat at altitude is 343 mph which is 12 mph more than the F4F-3 at an altitude that is not required and with added complexity.



We seem to have a lot of confusion here between singe stage engines, two stage engines and turbo engines. 
This is not helped at all by some sources that should know better confusing the different engines. 

The XP-41 is listed by the "National Museum of the Air Force" as using a turbo supercharger. However they also say the engine was a R-1830-*19 *which P & W lists as a mechanical two stage engine. So which is it?

I would also note that the -19 engine was rated at 1200hp for take-off but for 1050hp at 4,000ft, 1050hp at 11,000ft and 1050hp at 17,500ft all at 2550rpm.
The -19 engine was also supposed to have flown in a Hawk 75. 

Seversky had two prototypes at the 1939 fighter trials. One with a turbo (the AP-4, later P-43) and one with the two stage mechanical engine (AP-2, later XP-41). 
Please note that this 2 stage R-1830 _may_ have differed considerably from later 2 stage engines. A written description and photographs of the outside of the Curtiss plane (and P & W patent drawings?) show (or indicate) the auxiliary stage laying horizontal in bottom of the fuselage behind the engine unlike the later 2 stage engines where the aux stage is vertical and in the same housing as the primary supercharger. None of this is conclusive without better evidence. 
There are plenty of photos floating around with the wrong captions. 

The Vultee Vanguard never got a two stage engine. All of them seem to have gotten 2 speed single stage engines.


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## Shortround6 (May 18, 2019)

pinsog said:


> Does anyone have any data on the XP-41? That might be a good way to compare single stage vs turbocharged engines at SL-10,000 feet in the same airframe.



Unfortunately any data may be in archives, a lot of what is published seems to have been "extracted" from charts/graphs. I tend to doubt very highly that a variety of planes ALL hit their max speed at 15,000ft for example even though that makes a good basis for comparison. Some may have been a bit faster just under 15,000ft and some a bit faster just over 15,000. 

A lot of charts showed speeds in 5,000ft increments of altitudes. 
Also as noted the XP-41 may have used a two stage mechanical engine but a very early one and perhaps not comparable to the ones used in the F4F.


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## wuzak (May 18, 2019)

Reluctant Poster said:


> The exposed pipe may have been cheap and easy but it can't have been very effective. The surface area is too small to have an appreciable cooling effect. Look at a your car radiator and calculate the surface area of all those fins. In addition it must have had a disastrous effect on the aerodynamics. The P-47 installation is much better aerodynamically it wasn't just moved inside for aesthetics. The typical American practice of hanging the turbocharger in breeze was not a good idea. It may not have been too critical for bombers cruising at 160 mph but for fighters it would affect performance.
> The other thing to note is that turbulent flow is what you want for heat transfer but not what you want for drag. I've always been surprised that the leading edge intercooler of the P-38 worked at all.



For the exhaust pipe to turbo you don't actually want heat transfer, but a small amount may have been required in order for the turbine blades to live. 

Leaving the exhaust exposed to outside air may have given the required amount.

The P-47 layout also had a longer path to the turbo, so some heat would have been lost.

Temperature difference is the other main factor s heat transfer. In the case of exhausts compared to outside air at altitude, the temperature difference is substantial.


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## Shortround6 (May 18, 2019)

pinsog said:


> Shortround, I agree with your ‘shifting stuff around to fit turbo inside F4F-3’. I said back on page 6 or 7 that this would have needed to be done probably on the prototype, although I feel pretty sure it would fit, if done at the beginning.



Perhaps it would fit if done at the prototype stage, unfortunately timing is against it.
The XF4F-2 monoplane first flew in Sept 1937. after a few crashes and some other problems the rebuilt XF4F-3 (with a two stage engine) flies in Feb 1939.
The Army has had nothing but trouble with the XP-37 at this time but is persevering with the YP-37 but the first of 13 is not delivered until June of 1939 (after being ordered in Dec 1937).
This was one reason the Army ordered the P-40 in April of 1940(sorry 1939), they wanted turbos but needed reliable aircraft in the squadrons before they estimated the turbo would be ready for squadron service.
It took the army quite a while to sort out the turbo installation. They went through several different models of the turbo itself. They went through several turbo controllers and they went into combat in early 1942 with a system that needed to be replaced as it froze in certain conditions causing overspeeding of the turbo (and sometimes failure of the turbo).

Not sure what the advantage of a turbo Wildcat is if it delays production in 1940/41 and has maintenance/control issues in early/mid 1942. (or later?).

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## Glider (May 18, 2019)

Just to throw an odd ball into the equation I think the Macchi 202 could have been the basis of an interesting development. It has the performance, a sturdy undercarriage and was able to carry drop tanks. It lacks firepower and range but that is hardly unique in some of the planes at the time, such as a Seafire and the drop tanks may well help.

It obviously lacks another important requirement, a carrier but the Italians did get close.

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## Kevin J (May 18, 2019)

Glider said:


> Just to throw an odd ball into the equation I think the Macchi 202 could have been the basis of an interesting development. It has the performance, a sturdy undercarriage and was able to carry drop tanks. It lacks firepower and range but that is hardly unique in some of the planes at the time, such as a Seafire and the drop tanks may well help.
> 
> It obviously lacks another important requirement, a carrier but the Italians did get close.



I think the Re 2001 would have been better as it had range, but again its a 1942 service intro fighter just like the Macchi. The only fighter that could have been ready for 1941 is the Seafire Ib, but against it is its lack of robustness.


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## Glider (May 18, 2019)

Kevin J said:


> I think the Re 2001 would have been better as it had range, but again its a 1942 service intro fighter just like the Macchi. The only fighter that could have been ready for 1941 is the Seafire Ib, but against it is its lack of robustness.


According to Shores '_Malta The Hurricane Years_' the Macchi 202 entered combat over Malta in late September 1941 so it does fit in with the timescale. 

I certainly agree that range is the major issue, but its no worse than most and it does have the performance. The Macchi also has a better performance than the Re 2001 and is more robust than the Spitfire, so it stays as my outside contender.

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## Shortround6 (May 18, 2019)

What is the stalling speed? 

or take-off/landing distances? 

You have a wing that is about 75% as big as a Spitfire wing. The flaps look like simple split flaps and they may or may not have intermediate positions or be adjustable unlike the Spitfire which were all or nothing.

It doesn't matter if the plane can hit 350mph or not if you can't operated it off the majority of carriers at the time. 

Yes you could "fix" it, (bigger wing?) but what does the "fix" do the performance?

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## Reluctant Poster (May 18, 2019)

wuzak said:


> For the exhaust pipe to turbo you don't actually want heat transfer, but a small amount may have been required in order for the turbine blades to live.
> 
> Leaving the exhaust exposed to outside air may have given the required amount.
> 
> ...



Next time there's a cold winter day (minus 40 where I grew up) take your car for a drive, after the car has warmed up, stop the car, take off your mitts and grab the tailpipe. I think you will get a burn.


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## Conslaw (May 18, 2019)

What I gather from all of this is that it would have been exceedingly hard to make the F4F into a 350-MPH aircraft. What if they would have take the XF4U, and split its development into two paths, with one path being the path taken - the path to making it the best plane they could make it, but the other path geared to getting a stopgap 350-MPH carrier into service as soon as possible. This would mean keeping the fuel in the wings, probably unprotected, and with a lighter armorment. Supply of the R-2800 engine would be an issue, limiting production, but even getting one section of proto-corsairs on each carrier could have made things very interesting.

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## Shortround6 (May 18, 2019)

Post-war Allison was fooling around with a turbo compound engine, exhaust gases routed to a turbine that was connected to the crankshaft.






At high boost pressures the exhaust temperatures exceeded 1750 degrees F going into the turbine and were causing blade failures. The test program resorted to injecting ADI fluid (ater/alcohol) directly into the _exhaust_ piping to lower the exhaust gas temperature. This was with 1945-46 metallurgy not 1940-41 metallurgy.

There may have been a critical temperature of exhaust gas that could not be exceeded without causing problems while just a 100 degrees or so lower would allow the turbine quite a long life?

They didn't want to over cool the exhaust as it will lose power wanted to operate the turbine. a fine balancing act.

You can burn your hand on a exhaust pipe that is under 200 degrees. but 200 degree exhaust gas isn't going to provide hundreds of HP to drive the compressor of a turbocharger.


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## Reluctant Poster (May 18, 2019)

Shortround6 said:


> Post-war Allison was fooling around with a turbo compound engine, exhaust gases routed to a turbine that was connected to the crankshaft.
> View attachment 538593
> 
> 
> ...



My answer was a bit too facetious, I apologize to Wuzak. I will say, however, that based on my experience with gas turbines that I wouldn't rely on the cooling effect of that little piece of pipe to protect the turbine blades. It certainly is a very crude way of attempting to control turbine inlet temperature. I would be extremely surprised if the length of pipe dictated solely by the location of the engine vs the turbine could by sheer luck match the temperature drop required to protect the turbine. My guess is that they were routing the piping on the outside to keep the heat away from the superchargers.


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## Glider (May 18, 2019)

Shortround6 said:


> What is the stalling speed?
> 
> or take-off/landing distances?
> 
> ...



I don't pretend to know some of the details you are asking and its obvious that any alterations would inevitably increase weight and impact performance. However, you are starting with a 370+ mph aircraft and can take some hit on the performance and still meet the 350+ target the thread is aiming at. This is I suggest a more realistic approach than trying to find ways of making a slower aircraft faster.

As for take off distance I don't know. However I do know that the Macchi 202 had a very impressive climb. Time to 1,000 meters 39 seconds, 2,000 meters 1 min 28 sec, 3,000 meters 2 min 28 seconds, 4,000 meters 3 min 32 seconds so I don't think getting off the deck would be a problem. These figures are considerably better than a Spit V and there were few fighters that could outclimb a Spit at that time.


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## Shortround6 (May 18, 2019)

"_I will say, however, that based on my experience with gas turbines that I wouldn't rely on the cooling effect of that little piece of pipe to protect the turbine blades. It certainly is a very crude way of attempting to control turbine inlet temperature. I would be extremely surprised if the length of pipe dictated solely by the location of the engine vs the turbine could by sheer luck match the temperature drop required to protect the turbine. My guess is that they were routing the piping on the outside to keep the heat away from the superchargers._" 

You could be right, but the B-17s, B-24s, P-43s and to a lesser extent the P-38s all used the exposed pipe and the exposed turbocharger. After the P-39 fiasco they had to know that there was some drag penalty.
On the XP/YP-37 the turbo had been located right under the engine with more or less exposed exhaust piping.




but this was never repeated.

heat issue?
maintenance issue? Easier to check for leaks without having to take off exhaust shrouds?


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## GrauGeist (May 18, 2019)

The Japanese had an exposed turbo-supercharger on the Nakajima KI-87 prototype

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## wuzak (May 18, 2019)

Reluctant Poster said:


> Next time there's a cold winter day (minus 40 where I grew up) take your car for a drive, after the car has warmed up, stop the car, take off your mitts and grab the tailpipe. I think you will get a burn.



I doubt the exhaust pipe is the same temperature at the tailpipe as it is near the engine. Temperature having been lost on the way.

Also, I'd suggest that the tailpipe would be warmer on a hot summer's day (+40C) than on a cold winter's day (-40C). Maybe not a lot of difference, but a difference nonetheless.


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## wuzak (May 18, 2019)

Reluctant Poster said:


> My answer was a bit too facetious, I apologize to Wuzak. I will say, however, that based on my experience with gas turbines that I wouldn't rely on the cooling effect of that little piece of pipe to protect the turbine blades. It certainly is a very crude way of attempting to control turbine inlet temperature. I would be extremely surprised if the length of pipe dictated solely by the location of the engine vs the turbine could by sheer luck match the temperature drop required to protect the turbine. My guess is that they were routing the piping on the outside to keep the heat away from the superchargers.



It would probably not be to reduce the temperature to within the limits, but rather to increase the margin.

The routing of the exhaust pipe would be away from equipment.


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## fliger747 (May 19, 2019)

As long as no one else had 350 mph fighters it didn't matter _as much_. The Navy experimented with a turbocharged Corsair but in the event did not pursue. For much of the early war (maybe later also) much Pacific combat took place at medium and low altitudes. The Supercharger is probably a lighter and simpler avenue here for the mission. The engine was already maxed out at low alt MP wise. 

Especially at sea (or some place like Munda) _dispatch reliability_ was an important concern.

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## tomo pauk (May 19, 2019)

fliger747 said:


> As long as no one else had 350 mph fighters it didn't matter _as much_. The Navy experimented with a turbocharged Corsair but in the event did not pursue. For much of the early war (maybe later also) much Pacific combat took place at medium and low altitudes. The Supercharger is probably a lighter and simpler avenue here for the mission. The engine was already maxed out at low alt MP wise.
> 
> Especially at sea (or some place like Munda) _dispatch reliability_ was an important concern.



I'll disagree with 1st sentence - it did matter. A 350 mph fighter will have much better chances to do multiple passes against a 300 mph inbound strike. The 320 mph fighters might struggle to make even one pass against a 300 mph inbound strike, resulting in a 'scratch a flattop' message. 
Real-world examples might include inability of F4F-4s to catch torpedo-armed 'Kates' at Santa Cruz, that resulted in Lex being torpedoed and sunk. That is despite having a radar support, imperfect as it was back in 1941. Or, inability of Zeroes CAP to reliably intercept four B-26s at Midway. 
Granted, those are examples from 1942, but we can think of a scenario that involves Ju-88s, G3Ms or Pe-2s in 1941 and see how the seaborne interceptors stack against those. 

With that said, I tend to favor a R-2800 powered fighter for the USN in this thread - offered a lot of power under 20000 ft.


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## pinsog (May 19, 2019)

tomo pauk said:


> I'll disagree with 1st sentence - it did matter. A 350 mph fighter will have much better chances to do multiple passes against a 300 mph inbound strike. The 320 mph fighters might struggle to make even one pass against a 300 mph inbound strike, resulting in a 'scratch a flattop' message.
> Real-world examples might include inability of F4F-4s to catch torpedo-armed 'Kates' at Santa Cruz, that resulted in Lex being torpedoed and sunk. That is despite having a radar support, imperfect as it was back in 1941. Or, inability of Zeroes CAP to reliably intercept four B-26s at Midway.
> Granted, those are examples from 1942, but we can think of a scenario that involves Ju-88s, G3Ms or Pe-2s in 1941 and see how the seaborne interceptors stack against those.
> 
> With that said, I tend to favor a R-2800 powered fighter for the USN in this thread - offered a lot of power under 20000 ft.



Agree 100% with this. Also, the Zero wasn't a 350 mph fighter at this time, but you really needed a 350 mph fighter to effectively combat it, or at least an altitude advantage so you can make a diving pass and breakaway, gain separation and climb back up for another pass.

Also fliger747, the P&W 1830 in the F4F-3 was doing 1100 hp at SL, at 5,500 feet was already down to 1050 hp, and was down to 1,000 hp at 12,200. A turbocharged P&W 1830 or even a turbocharged Wright 1820 was rated at 1,200 hp from SL up to 25,000 feet. That is 10% more hp at SL, 15% more hp at 5,500 feet and 20% more hp at 12,200. All of those altitudes are right where Japanese torpedo and dive bombers operated when going after US carriers.
10% more hp is significant.
15% more hp is really significant
20% more hp is freakin' huge

Whats the difference in performance between a 2,000 hp Thunderbolt and a 2,400 hp Thunderbolt? A lot.
Whats the difference in performance between a 2,000 hp Corsair and a 2,400 hp Corsair? A lot.
Whats the difference in performance between a 1,500 hp Spitfire and an 1,800 hp Spitfire? A lot.

20% is a huge jump.

Tomo pauk, we would all prefer an R2800 powered fighter in 1941-42 but the engine timeline doesn't work out. A turbocharged F4F-3 is at least possible.


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## pinsog (May 19, 2019)

Shortround, will a turbocharger heat the intake air more than a supercharger at low altitude? If an F4F-3 and a turbocharged F4F-3 are both running at 1100 hp, side by side at 1000 feet, could they use the same intercooler? Or does a turbocharger produce more heat for a given hp than a supercharger?

My reason for asking is, instead of installing a larger intercooler like you would need at 25,000 feet, just use the original intercooler and you would still gain 100 hp down low. Or maybe slightly increase the size of the intercooler to get 1,200 hp up to 20,000 feet instead of 25,000 feet.


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## tomo pauk (May 19, 2019)

pinsog said:


> Tomo pauk, we would all prefer an R2800 powered fighter in 1941-42 but the engine timeline doesn't work out. A turbocharged F4F-3 is at least possible.



P&W delivered nine R-2800s from Jan-Nov 1940 (those can go in the prototypes), another eight in Dec 1940, another hundred before end of the March of 1941.

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## pinsog (May 19, 2019)

Also Shortround, I knew they had turbocharger control problems early on, I have an idea on how this might have worked with perfect hindsight.

Grumman sees tests on AP-4/P43 in 1939. Hey guys they are getting 1200 hp at 25000 feet with that. Grumman builds an F4F-3 with a turbo in the same position as the P43. US Navy is unsure about it, not trusting it yet. Grumman plumbs the production F4F-3 with the holes in the proper place, fuel tank curved on the bottom, radios behind the seat mounted up higher, etc. Essentially the bolt holes are there but the equipment is not installed, and it is shipped with the original P&W 1830 2 stage engine. But, it is set up so that if the Navy sees fit to change over to the turbocharged engine, it is a simple matter of installing the turbo, ducting, controls etc in the bolt holes provided. 

It didn't happen, but at least that might be a plausible plan.


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## Shortround6 (May 19, 2019)

tomo pauk said:


> With that said, I tend to favor a R-2800 powered fighter for the USN in this thread - offered a lot of power under 20000 ft.



Trouble is for _production_ fighter in 1941, you are stuck with the R-2800-5 (or equivalent) that offers 1850hp from sea level to 2700ft (plenty of power) but is down to 1500hp at 14,000ft in high gear , which is still a lot of power but the engine weighs 2270lbs. and is 52in diameter (bare engine). 

the figures for the power for the F4F-3 may be true but they don't tell the whole story. The F4F-3 (not the F4F-3A) would hold 1050hp to 11,000ft and would hold 1000hp to 19,000ft (no ram). the R-2800-5 may have down under 1400hp at 19,000ft. 
The engine used in Corsair would give 1800hp at 15,500ft. without water injection. 20% more power over 10% higher up.


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## tomo pauk (May 19, 2019)

Shortround6 said:


> Trouble is for _production_ fighter in 1941, you are stuck with the R-2800-5 (or equivalent) that offers 1850hp from sea level to 2700ft (plenty of power) but is down to 1500hp at 14,000ft in high gear , which is still a lot of power but the engine weighs 2270lbs. and is 52in diameter (bare engine).
> 
> the figures for the power for the F4F-3 may be true but they don't tell the whole story. The F4F-3 (not the F4F-3A) would hold 1050hp to 11,000ft and would hold 1000hp to 19,000ft (no ram). the R-2800-5 may have down under 1400hp at 19,000ft.
> The engine used in Corsair would give 1800hp at 15,500ft. without water injection. 20% more power over 10% higher up.



I'm not_ stuck_ with R-2800-5, I'm (or, USN is) _blessed_ with it.


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## Shortround6 (May 19, 2019)

pinsog said:


> Shortround, will a turbocharger heat the intake air more than a supercharger at low altitude? If an F4F-3 and a turbocharged F4F-3 are both running at 1100 hp, side by side at 1000 feet, could they use the same intercooler? Or does a turbocharger produce more heat for a given hp than a supercharger?



I don't think it makes much difference, Both the P & W aux stage and the GE turbocharger were somewhat less than ideal (lower efficiency) at this point. The whole idea of the turbo at this point in time was try to duplicate sea level conditions at higher altitudes so at low altitude the waste gate is wide open and the turbo is "idling" providing little or no boost.
Of course at low altitude the P & W auxiliary supercharger is not clutched in either so it is not providing any boost or creating any heat in the intake tract. 

You don't get any additional power at low altitude. 

It is not until either the Aux supercharger is clutched in or the turbo engine gets to around 3700-4000ft that the waste gate will begin to close and provide any boost to the engine that intercoolers have any role at all. On a turbo engine the army's goal for the intercooler was to keep the intake air from exceeding 100 degrees F at the inlet to the carburetor. 



> My reason for asking is, instead of installing a larger intercooler like you would need at 25,000 feet, just use the original intercooler and you would still gain 100 hp down low. Or maybe slightly increase the size of the intercooler to get 1,200 hp up to 20,000 feet instead of 25,000 feet.



The turbo doesn't take any power from the engine to drive so you gain there, the question is what point does the rise in intake temperature come into play.


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## Shortround6 (May 19, 2019)

tomo pauk said:


> I'm not_ stuck_ with R-2800-5, I'm (or, USN is) _blessed_ with it.



What I mean is that is only engine in production in numbers in 1941. There is no other version. 

It weighs 800lbs more than an R-1830 single stage 2 speed engine and about 700lbs more than the two stage engine. 

Most of your extra power is going to be used up hauling around the extra weight and bigger airframe needed to hold the engine and the rest of the powerplant.

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## pinsog (May 19, 2019)

Shortround6 said:


> I don't think it makes much difference, Both the P & W aux stage and the GE turbocharger were somewhat less than ideal (lower efficiency) at this point. The whole idea of the turbo at this point in time was try to duplicate sea level conditions at higher altitudes so at low altitude the waste gate is wide open and the turbo is "idling" providing little or no boost.
> Of course at low altitude the P & W auxiliary supercharger is not clutched in either so it is not providing any boost or creating any heat in the intake tract.
> 
> You don't get any additional power at low altitude.
> ...



Makes sense so far. So if they installed a turbocharger, would they be able to get 1200 hp from 12000-19000 instead of 1000 because they aren't having to use engine power to turn high gear on the 2 stage supercharger and still use the same intercooler? (not sure how much power it took to spin high gear on a P&W 1830-76)

Might be close to break even weight on a turbocharged F4F-3 if they used the Wright 1820 instead of a P&W 1830.


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## tomo pauk (May 19, 2019)

Shortround6 said:


> What I mean is that is only engine in production in numbers in 1941. There is no other version.
> 
> It weighs 800lbs more than an R-1830 single stage 2 speed engine and about 700lbs more than the two stage engine.
> 
> Most of your extra power is going to be used up hauling around the extra weight and bigger airframe needed to hold the engine and the rest of the powerplant.



I don't need another version, this one will do. Yes, it is heavier than R-1830 of any favor, but nobody is expecting a free lunch here.

On the other hand, how about a derivative of the R-2180A? The 2-stage supercharged version was suggested by the P&W, so was the turboed.


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## Kevin J (May 19, 2019)

tomo pauk said:


> P&W delivered nine R-2800s from Jan-Nov 1940 (those can go in the prototypes), another eight in Dec 1940, another hundred before end of the March of 1941.


Were these single stage, two stage or both?


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## tomo pauk (May 19, 2019)

Kevin J said:


> Were these single stage, two stage or both?




Vast majority were of 1-stage supercharged type.

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## Shortround6 (May 19, 2019)

Kevin J said:


> Were these single stage, two stage or both?


Just about all were single stage.

for B-26 fans these are the engines that went into the early B-26s.

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## Shortround6 (May 19, 2019)

tomo pauk said:


> On the other hand, how about a derivative of the R-2180A? The 2-stage supercharged version was suggested by the P&W, so was the turboed.


 P & W built about 30 of the R-2180 engines so the existence of actual production tooling for many parts is questionable. 

It used the same bore and stoke as the R-2800 so piston and cylinder parts may be available but production of this engine is only going to cut into/delay the R-2800.

Development was shut down before the war started but the best it ever did seems to be 1400hp for take-off and most versions/proposals don't even mention military power. 
It also has the same diameter as the R-2800 so it is no help in streamlining.

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## Shortround6 (May 19, 2019)

pinsog said:


> Makes sense so far. So if they installed a turbocharger, would they be able to get 1200 hp from 12000-19000 instead of 1000 because they aren't having to use engine power to turn high gear on the 2 stage supercharger and still use the same intercooler? (not sure how much power it took to spin high gear on a P&W 1830-76)
> 
> Might be close to break even weight on a turbocharged F4F-3 if they used the Wright 1820 instead of a P&W 1830.



The R-1830 is a bit hard to estimate because P & W only gave a few versions an actual military rating. They allowed 2700rpm for take off but those altitude ratings given in previous posts were at 2550rpm.

edit. The pilot's manual for the F4F-4 also does not list a military power. 
It does give an emergency take-off power setting using 2900rpm but restricts it to one minute only *and *rescinds permission to use this rpm for emergency climb. It says this rpm should only be used with the prop set to a fixed pitch and that is OK for take-off. 
I have no idea if this restricting the R-1830 in the wildcat was due to cooling problems with engine, or a propeller governor problem or what???
It doesn't matter if the engine is using the auxiliary supercharger or not or what the gear the aux supercharger is in.


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## Kevin J (May 19, 2019)

With a first flight date of May 29th 1940, it seems to me that it would be very unlikely that the Corsair could have seen operational service any time in 1941. Maybe if the Hellcat rather than the Skyrocket had flown first in 1940 with a single stage R-2800 then maybe maybe 1941, but at Pearl Harbour there was only one carrier operating the Wildcat, so does the Wildcat get canned?


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## Shortround6 (May 19, 2019)

Kevin J said:


> but at Pearl Harbour there was only one carrier operating the Wildcat,



This may be technical true but it would seem to need at least a few qualifiers?

In Jan 1942 the Last US navy carrier Squadron landed it's F2A Buffaloes (gave them to the Marines) so either there was a truly massive and rapid requirement or something is out of whack.

Grumman had completed 402 Wildcats and Martlets by the end of Nov of 1941. 106 of those had been built in 1940. How many went to the Royal navy Bty Dec 7th I don't know.

At least one US carrier was being used as an aircraft ferry at the time of Pearl Harbor to bring planes to Midway and Wake so perhaps it's own squadrons were ashore on Hawaii on Dec 7th?

You also have this from wiki "When the Japanese attacked Pearl Harbor on 7 December 1941, _Saratoga_ was entering San Diego Harbor to embark her air group, which had been training ashore while the ship was refitting. This consisted of 11 Grumman F4F-3 Wildcat fighters of VF-3 (under the command of Lieutenant Jimmy Thach), 43 Douglas SBD Dauntless dive bombers of VB-3 and VS-3, and 11 Douglas TBD Devastator torpedo bombers of VT-3. The ship also was under orders to load 14 Marine Corps Brewster F2A-3 Buffalo fighters of VMF-221 for delivery in Oahu. "
So the Saratoga was not anywhere near Pearl Harbor on Dec 7th and had no planes of any kind on board having just left the Bremerton navy yard after a nearly year long modernization and refit.
Of the 7 US Carriers only 3 (including the Saratoga) were in the Pacific, the other 4 were in the Atlantic. So all four of them could be said not to be at Pearl Harbor, doesn't mean they didn't have Wildcats on board. 

I would note that Grumman was increasing production and built another 332 F4Fs in the first 4 months of 1942 and for the rest of the year production never dropped below 100 per month.

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## Kevin J (May 19, 2019)

Shortround6 said:


> This may be technical true but it would seem to need at least a few qualifiers?
> 
> In Jan 1942 the Last US navy carrier Squadron landed it's F2A Buffaloes (gave them to the Marines) so either there was a truly massive and rapid requirement or something is out of whack.
> 
> ...


The RN got about half the 1940/41 production.


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## Conslaw (May 20, 2019)

If it had been a high enough priority, and had there been a willingness to accept that better is the enemy of "good enough", a limited production version of the XF4U could have been available in 1941. Consider that the XF4U's first flight was in May 1940. The prototype for the A6M Zero first flew in April 1939, and 13 service-test units went into combat late summer 1940. An equivalent timeline for the Corsair would be fall 1941. Of course, this theoretical Corsair wouldn't be the one we know. It would be an extremely buggy 350+ MPH fighter which could occasionally take off and land from a carrier without killing the pilot. It would be undergunned and probably would not have protected fuel tanks. 

As to the 800 lb weight penalty of the R-2800 over the R-1830, the XF4U flew 405 MPH in October 1940. Even with 1800 nominal horsepower that gives it a cushion of speed to lose in the transition from prototype to in-service fighter and still top 350 mph.


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## Kevin J (May 20, 2019)

Conslaw said:


> If it had been a high enough priority, and had there been a willingness to accept that better is the enemy of "good enough", a limited production version of the XF4U could have been available in 1941. Consider that the XF4U's first flight was in May 1940. The prototype for the A6M Zero first flew in April 1939, and 13 service-test units went into combat late summer 1940. An equivalent timeline for the Corsair would be fall 1941. Of course, this theoretical Corsair wouldn't be the one we know. It would be an extremely buggy 350+ MPH fighter which could occasionally take off and land from a carrier without killing the pilot. It would be undergunned and probably would not have protected fuel tanks.
> 
> As to the 800 lb weight penalty of the R-2800 over the R-1830, the XF4U flew 405 MPH in October 1940. Even with 1800 nominal horsepower that gives it a cushion of speed to lose in the transition from prototype to in-service fighter and still top 350 mph.


Sounds like a deathtrap. I think I'd prefer to be flying a Douglas Dauntless as a fighter.

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## Shortround6 (May 20, 2019)

Ugh, guys
*XF4U-1* that flew in 1940






Guns in cowl and one gun in each wing. cockpit about 3 ft further forward than production planes. Fuselage tank nonexistent, No fuel tanks were self sealing. 
about 397 other "minor" changes before production. 

BTW the prototype did NOT use a single stage engine. It used either the R-2800-X2 engine or the R-2800-X4 (at different times).
While take-off for the X-2 was 1850hp at 26000rpm it was rated at 1500hp at 17,500ft at 2400rpm, I am guessing in high gear ( it did have two stage engine).
The X4 was good for the same 1850hp at 2600rpm for take-off but was rated at 1600hp at 2400rpm at 3500ft, 1540hp at 2400rpm at 13,500ft, and 1460hp at 2400rpm at 21,500ft.
These are all "Normal" power or max continuous (1 hour rating or longer). 

The -5 engine in the B-26 was rated at 1450hp at 2400rpm at 13,000ft. "Normal" power. 

Good luck getting a 350mph airplane at 14-16,000ft. using the -5 engine. 
A production F4U-1 did just under 370mph at 15,000ft using 1625hp and just under 390mph using 1800hp at 15,000ft. in one test,
British claim about 365mph at 15,000ft using full military power. (about 1800hp). I have no idea why the 20+mph difference.

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## GrauGeist (May 21, 2019)

Kevin J said:


> With a first flight date of May 29th 1940, it seems to me that it would be very unlikely that the Corsair could have seen operational service any time in 1941. Maybe if the Hellcat rather than the Skyrocket had flown first in 1940 with a single stage R-2800 then maybe maybe 1941, but at Pearl Harbour there was only one carrier operating the Wildcat, so does the Wildcat get canned?


The USS Ranger received F4F-3s in December 1940.
By 7 December 1941, many of the USN's carriers had the F4F, like the Yorktown, Wasp, Enterprise, Lexington, Saratoga and Hornet.


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## Conslaw (May 24, 2019)

Shortround6 said:


> I don't think it makes much difference, Both the P & W aux stage and the GE turbocharger were somewhat less than ideal (lower efficiency) at this point. The whole idea of the turbo at this point in time was try to duplicate sea level conditions at higher altitudes so at low altitude the waste gate is wide open and the turbo is "idling" providing little or no boost.
> Of course at low altitude the P & W auxiliary supercharger is not clutched in either so it is not providing any boost or creating any heat in the intake tract.
> 
> You don't get any additional power at low altitude.
> ...




So in those days turbocharging was only/primarily used to get sea level performance at altitude? Of course geared supercharger were already used to enhance sea level performance, when did things change and turbochargers get unleashed at low level? Now turbocharged cars are ubiquitous.


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## Shortround6 (May 24, 2019)

Conslaw said:


> Now turbocharged cars are ubiquitous.


Difference is that the engine driven supercharger on some of those aircraft engines was delivering 7-9lbs of boost several thousand feet above sea level. They could deliver more boost than the fuel would support without knocking or detonating.



Conslaw said:


> So in those days turbocharging was only/primarily used to get sea level performance at altitude?



That was the Army's goal. Please remember that the US Army had been working with turbo-chargers since the late 20s. Fuel may have been 70-77 octane. The early engines had no engine driven supercharger. AS fuel got better and the engine makers added or improved the superchargers on their engines (on some 1920s radials they were actual called mixing fans to improve the distribution of fuel and increase atomization rather than really increase boost). The US went to 100 octane fuel before anybody else but due to an insistence not to use aromatic compounds it was pretty much 100/100 fuel and not 100/130. This limited the amount of boost that could be used (still better than 87 octane) even running rich. 

The Early P-38s used 6.44 supercharger gears instead of the 8.80 gears to get more take-off power and used the turbo to get altitude performance even in the teens that they would have lost compared to the "altitude rated" engines with their 8.80 gears. The P-38F switched to 7.48 gears and the P-38H went to 8.10 gears. But by that time the P-40s and P-39s were using 9.60 gears. This is one reason the "military power" of the P-38 engines was always higher than the non-turbo engines of the same time period. They were using the turbo to make for the lower pressure of the engine powered supercharger. By spinning the supercharger slower it took less power leaving more power available to drive the propeller. 
The radial engines were rarely geared (supercharger wise) for even medium altitude performance. The R-1830 and R-1820 during 1939-1942 could only hold 1200hp to around 3-5000ft. 
By changing gears you could get more power in the low teens but on a single speed engine that meant giving up 100hp or more for take-off/low altitude to prevent detonation. 
The turbo R-1830, R-1820, R-2800 engines all used the lowest the supercharger gear the company offered in order to get the best take-off/base line performance. 

10/130 fuel changed things. 




Conslaw said:


> Of course geared supercharger were already used to enhance sea level performance, when did things change and turbochargers get unleashed at low level?


The turbos got "unleashed" once;
A) better materials were used in the basic engines.
B) 100/130 fuel became wide spread (for the US this meant sometime in 1942, plans for "hot rod" aircraft have to take into account that the fuel development was faster than either engine development or airframes).
C.) WEP ratings were approved (trading increased maintenance and shorter engine life for increase performance)
D) Water injection was introduced to allow even higher boosts than 100/130 fuel would allow on the air cooled engines. 
E) 1944, the introduction of 100/150 fuel along with water injection on the P-47s. 

trying to used turbo on an R-1830 in 1940-41 to bump up the pressure at low altitude fails at least 3 of those conditions. Perhaps they could have OKed a higher power setting and gotten less engine life. but the increase would not have been as large with the poorer fuel and the maintenance and blown engines would have been higher. Water injection might have seen a quicker service introduction (jimmy Doolittle was fooling around with it in the early 30s) but I don't know how far the experiments were from service introduction.

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## Conslaw (May 25, 2019)

Shortround6 said:


> Difference is that the engine driven supercharger on some of those aircraft engines was delivering 7-9lbs of boost several thousand feet above sea level. They could deliver more boost than the fuel would support without knocking or detonating.
> 
> 
> 
> ...




Jimmy Doolittle's work for Shell Oil - as a champion for 100-octane fuel, probably did more for the allied war effort than the raid on Tokyo.


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## Csch605 (May 25, 2019)

GrauGeist said:


> The USN had considered the P-36 for potential naval service, but not the P-40.
> 
> On the otherhand, they did consider and evaluate a P-39 (XFL-1).
> 
> ...


Without the 37 mm this thing does not scare me one bit. Looks like a scared puppy. Although she is really clean and quick looking.

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## pinsog (Oct 14, 2019)

tomo pauk said:


> I'm not sure about diameter of the piping, however, there was the XF4F-5, with R-1820 + turbo. Seems like the B-17Bs were delivered with similar powerplant from second half of 1939 on - 1200 HP up to 25000 ft. No problems encountered when flying to Brazil and back (in several 'hops', of course).
> Might be an interesting read: link


Tomo pauk, quick question, where was the turbo installed on the XF4F-5?


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## GrauGeist (Oct 14, 2019)

Two F4F-3s were held back as the XF4F-5 and each one was tested with a supercharged engine.

BuNo 1846 was fitted with a turbo-supercharged R-1820-54 engine and BuNo 1847 was fitted with a two-stage supercharged XR-1820-48 engine.


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## pinsog (Oct 14, 2019)

GrauGeist said:


> Two F4F-3s were held back as the XF4F-5 and each one was tested with a supercharged engine.
> 
> BuNo 1846 was fitted with a turbo-supercharged R-1820-54 engine and BuNo 1847 was fitted with a two-stage supercharged XR-1820-48 engine.


Do you have any idea where they put the turbocharger on #1846?


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## ThomasP (Oct 15, 2019)

Hey Shortround6 & pinsog,

re: Military rating for the R-1830 2-stage at altitude

There is a NACA test report on the R-1830-86 2-stage as used in the F4F floating around somewhere on the internet (my apologies for not being able to provide a link but I ran across it several years ago, before I ever planned to post on this site). I believe the test was titled "Calibration of the P&W R-1830-86 engine" or something very close to that.

In the report it talks about the changes incorporated to increase the power (to 1100 BHP) at altitude (from memory somewhere around 18K ft) using UK 100/130 equivalent fuel (i.e. having a high aromatic content). The date of the test was early-1943, before(?) widespread availability of the US equivalent fuel grade using alkylates. Again, if my memory is correct, the engine tested was modified with a new carburetor and fitted with 'C' type cylinders (i.e. a modified design with increased cooling area similar to the type used on the 'C' series R-2800 and R-2600 engines). There did not seem to be any problem obtaining the power, at least under test conditions, and NACA recommended adoption of a 1100 BHP at altitude Military rating.


re: 2-stage BHP vs turbo BHP

Although this only an educated guess on my part, I suspect that the difference in BHP between the mid-war R-1830 installations on the B-24 with turbo (1200 BHP) and the F4F-3 &-4 (1100 BHP) indicates that the difference in BHP absorbed by the installations at altitude was about 100 BHP??


re: cooling problems on the R-1830-76 and -86

My understanding relative to the F4F fitted with the R-1830-76 & -86 2-stage engine was that the primary problem was cooling under sustained high power settings. The Normal power ratings (as I am sure you are already aware) were 1100/1050/1000 BHP from SL to 19,500 ft. The reason for the very poor climb rates of the F4F-3 & -4 in service was that the early engines (without the 'C' type cylinders) could only sustain about 930 BHP for more than a few minutes under climb conditions due to overheating. This is why we see the reduction in the Grumman F4F-3 Detail Specification estimate/guarantee climb rate from 3300-3070 ft/min to 1890 ft/min in service, and the F4F-4 Detail Specification having an estimate/guarantee of only 1690 ft/min.

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## Shortround6 (Oct 15, 2019)

ThomasP said:


> In the report it talks about the changes incorporated to increase the power (to 1100 BHP) at altitude (from memory somewhere around 18K ft) using UK 100/130 equivalent fuel (i.e. having a high aromatic content). The date of the test was early-1943, before(?) widespread availability of the US equivalent fuel grade using alkylates.



By early 1943 the US and Britain were on their 3rd joint specification for 100/130 fuel. The first called for much increased (over US standards) use of aromatic compounds and up to 3cc of lead (per US gallon), the 2nd allowed for up to 4.6cc of lead per gallon and little or no change in aromatics from the first specification. The 3rd held at 4.6 cc of lead but allowed different aromatics to be used. It was this 3rd specification that caused trouble with the engines in the P-38s. BY 1943 which may have been when the report was written(?) (but actual testing down months earlier?) US fuel was equivalent to British fuel, individual refineries fuel could differ but ALL aviation fuel was being made to the same specifications. 



ThomasP said:


> the engine tested was modified with a new carburetor and fitted with 'C' type cylinders (i.e. a modified design with increased cooling area similar to the type used on the 'C' series R-2800 and R-2600 engines).



There were some R-1830 engines built near the end of war that were rated at 1350hp for take off. I don't know about the carburetors but the cooling fin arrangement was changed. Quite possibly to something similar to the R-2800 C series. These engines seem to show up mostly on P4Y-2s (or C-87s) as single stage two speed engines. There were also allowed to run at 2800rpm instead of 2700rpm which doesn't make power comparison any easier. A few may have showed up in B-24Ns with turbos. 

The R-2600 (and late R-1820s) got better cooling fins but they used a different method of construction, the fins were sheet metal and pressed into place in grooves in the cylinder barrel.
P&W was using forged/machined fins on the cylinder barrel. The late R-1830s got their fins on a muff or jacket that was slid over the cylinder wall, as did R-2800s (THE "C" got more/larger fins).


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## tomo pauk (Oct 15, 2019)

pinsog said:


> Tomo pauk, quick question, where was the turbo installed on the XF4F-5?



By the look at pic found at the 'America's hundred thousend' book pg. 472, my best guess is that it was installed just behind the engine.



ThomasP said:


> ...
> re: 2-stage BHP vs turbo BHP
> 
> Although this only an educated guess on my part, I suspect that the difference in BHP between the mid-war R-1830 installations on the B-24 with turbo (1200 BHP) and the F4F-3 &-4 (1100 BHP) indicates that the difference in BHP absorbed by the installations at altitude was about 100 BHP??



Difference at 25000 ft was probably more than 300 HP, where the turboed R-1830 was still rated for 1200 HP military power.




> re: cooling problems on the R-1830-76 and -86
> 
> My understanding relative to the F4F fitted with the R-1830-76 & -86 2-stage engine was that the primary problem was cooling under sustained high power settings. The Normal power ratings (as I am sure you are already aware) were 1100/1050/1000 BHP from SL to 19,500 ft. The reason for the very poor climb rates of the F4F-3 & -4 in service was that the early engines (without the 'C' type cylinders) could only sustain about 930 BHP for more than a few minutes under climb conditions due to overheating. This is why we see the reduction in the Grumman F4F-3 Detail Specification estimate/guarantee climb rate from 3300-3070 ft/min to 1890 ft/min in service, and the F4F-4 Detail Specification having an estimate/guarantee of only 1690 ft/min.



I'd say that problem with F4F trying to climb was that it was too much of an airplane for the R-1830 to haul around, especially the fully navalized F4F-4 with 6 heavy MGs and full protection for pilot and fuel. Such a big and heavy aircraft needed perhaps 50% more power to climb well and fly fast.

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## pinsog (Oct 15, 2019)

tomo pauk said:


> By the look at pic found at the 'America's hundred thousend' book pg. 472, my best guess is that it was installed just behind the engine.
> 
> 
> 
> ...


I have that book. Thank you. Found it. 

If the turbocharger will survive the heat of the exhaust that powers it while being that close, then adding a turbocharger would have been very simple and could have been done anytime very easily with virtually no modification. Just a bit of sheet metal work from the firewall forward along with new mounts etc.


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## ThomasP (Oct 16, 2019)

Hey guys,

I found the NACA document I mentioned above. The full title is "Calibration of Pratt & Whitney R-1830-86 Engine" and the link is: 

"https://apps.dtic.mil/dtic/tr/fulltext/u2/a800376.pdf"


Hey Shortround6,

The dates of the test were from 6 March 1942 to 21 April 1942. My understanding is that that was about the time that the US started testing the ~final blend(s?) of 100/130 grade fuel similar to the UK ~final 100 octane blend(s?), but I do not for sure.

The report identifies the fuel type as having 20% aromatic content, and compares the results (in a very general way in one paragraph) to those using AN-VV-F-781-4. I find the wording "with regular Specification AN-VV-F-781-4 and approximately 16 percent aromatic 100 octane fuels" (page 4 paragraph 5) confusing. I can not tell if this refers to 2 or more different fuel specifications (i.e. AN-VV-F-781-4 AND 16% aromatic fuels) or if AN-VV-F-781-4 has 16% aromatic content?? Also I do not know for sure which of the different specifications fits a 20% aromatic content, if any, although I remember reading that the one of the standard UK 100 octane blends (100/130 grade) used this content. If you have any idea I would appreciate the info.

Unfortunately the report does not specify the exact mods to the cylinders to aid cooling (i.e. muffs, fins, heads, cylinder sleeves, etc.).


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