WHAT IF: Longer range P-47 from start

[davparlr]

True.
How many viable radial engines did the US develop?

Tons! R-1820, R-1830, R-2600, R-2800, R-3350, R-4360.

How many viable inline engines did the US develop?

Not so much. I think that only the Allison was successful. Its biggest problem seemed to be a decent supercharger.

 

[gjs238]

It would have been interesting if development of the Ford GAA engine was supported.
Edit: The aircraft version that is.

 

[Shortround6]

Did the British have issues with the P-38 and P-47 that drove them to Merlinize the P-51?

The only British experience with the P-38 was with a couple of early ones that had the turbos removed and both props turning the same way. Performance was so underwhelming they canceled the rest of the contract.
The First thunderbolts they got were from the P-47D-22 production block which is after the decision to put Merlins in the Mustang. Remember that the British ordered and paid for the Mustang on their own. As soon as it went operational they had a very good idea of well it performed with the Allison engine. They started flight testing in Jan of 1942 and first flew operationally over France in May of 1942. Planes to install Merlins were taking Place in July and August. First P-38s (with turbos) in US hands don't get to England until June or July of 42? First US P-47s don't make it to England until Dec of 1942 as deck cargo.
There is a lot of work/development going on in parallel. With the months of lead time needed to tool-up, allocate resources, produce planes and ship them to combat theaters, waiting to get combat reports can take too long.

 

[Shortround6]

Probably more then the rest of the world combined. Air cooled radial engines were not a problem for the USA.

Liquid cooled V12s are an entirely different matter. So the U.S. Army Air Corps had better fund development when they order the P-38 during February 1937. Otherwise the new fighter aircraft ordered during 1937 should be powered by an R2800 engine, which was in development during 1937.

Once again you need a timeline. The Allison passed a type test at 1000hp in 1937. while the R-2800 was in development in 1937 it wouldn't pass a type test until July 1st 1939. It wasn't flown until July 12 1939. First production engine doesn't complete model test until March 25,1940. Engineering man hours until the completion of the type test in 1939. 325,000.
The R-2800 was in no way, shape or form available to power anything until 1941.
Allison built 1149 B-1710s in 1940 compared to P&W building 17 R-2800s (8 of them in Dec.) 1941 saw Allison build 6402 V-1710s compared to P&W building 1469 R-2800s. All but a handful of these were 1850hp single stage supercharged engines for B-26 bombers.

As for ditching the battleship construction, hindsight is a wonderful thing.
In 1937 when the program started every carrier in the world was equipped predominantly with biplanes. The US was just introducing the Douglas TBD Devastator torpedo bomber. From Wiki " It was the first widely-used carrier-based monoplane as well as the first all-metal naval aircraft, the first with a totally-enclosed cockpit, the first with power-actuated (hydraulically) folding wings" it also had an 800hp engine. Trying to guess that in 5 years carrier strike planes would use engines of double the power with vastly improved bomb loads (double) and vastly improved speed and range might have been a little difficult.
edit>
In 1937-40 you would also be betting that radar will be developed so you will have night/all weather detection or warning of enemy ships approaching so your carriers don't get surprised by enemy surface units like what happened to the HMS Glorious.
It is real easy in 2011 to criticize decisions made in 1937-39. Some criticisms may be valid but without understanding the facts of the time or the conditions, like what treaties are in force, some criticism loses credibility. USS Wasp (CV-7) was built to a smaller size than the preceding Yorktown and Enterprise because there wasn't enough tonnage left under treaty limits to build a third carrier of that size. The US was allowed to build battleships however. Just because Navy funding is cut does not mean Army Air Force money would be increased.

 

[davebender]

What does that mean? How many hours did this 1,000hp engine run before it failed?

 

[gjs238]

The USAAC was using the P-47 [and the P-38] to escort bombers before using Merlin-powered P-51's for that purpose.
The P-47's lack of range and the P-38's reliability were serious issues that led to use of Merlin-powered P-51's for escort.
Edit: That's not to say that even if the P-47 P-38 performed the escort job perfectly the P-51 would never have participated in this task.

Perhaps the British were developing or using Merlin-powered P-51's prior to using decent versions of the P-38 P-47, but the opposite is true of USAAC escort duty.

 

[Shortround6]

It had to run 150hrs. The Allison was the first engine to pass the Army's new test. This test was adopted by the Navy and for all commercial engines in the US.

10hrs at take-off power; 40hrs at rated power or 91% of take-off power, whichever is greater; 10hrs at over speed; other miscellaneous requirements. Take-off test may be run continuously or broken into 120 5-in segments alternated with 120 5-min periods at idle. The overspeed test may also be broken into 30sec or 60sec periods alternating with 5 min idle periods. Certain repairs are allowed during the test (spark plug changes and perhaps valve or valve spring replacement) with either no penalty or a penalty of extending the hours of the test but a major failure would require starting over. Of interest is the fact that the first Merlin subjected to this test did worse than the Allisons and might have been failed if the war situation had not been so dire and the British engines not in widespread use at the time.

 

[gjs238]

In defense of the V-1710, it was developed long before Hooker did his magic on the Merlin (altitude performance wise.)
If Hooker's improvements had not occurred, the V-1710 may be looked upon a bit differently today.
In that case, the British may very well have (had to) embrace the P-38 and P-47 for high altitude work.
Or maybe use larger displacement engines like the Germans did.

 

[Shortround6]

Perhaps the British were developing or using Merlin-powered P-51's prior to using decent versions of the P-38 P-47, but the opposite is true of USAAC escort duty.

In June of 1942 Rolls Royce is working on a preliminary study of putting a Merlin in a Mustang. Also in June of 42 North American gets a contract to convert two P-51s to Packard Merlin power. By august a prototype installation is made by NA and 5 Mustang Is are sent to Rolls Royce. In august an order for 400 P-51Bs is placed. In Oct 1942 the First flights are made of the Mustang X (Merlin powered Mustang in England) In Nov 1942 First flights of the NA Merlin Powered Mustang are made with engine over heating, radiator and air scoop need redesigning. In Dec flights resume. Jan 1943 2000 P-51 Bs with Merlins are ordered by the USAAF. Light weight versions (XP-51F,G and J) are started as an RAF program. Feb 1943 the 201 202 P-51B airframes are assigned for use as prototypes for the P-51D. March 10 1943 P-47s make first operational flight over France April 1943 2500 P-51Ds are ordered. May 1943 First flight is made by a production P-51B. Sept 1943 First P-51B arrives in England.

While USAAC was using P-47s and P-38s for escort duty before they used P-51s for escort duty the problems or limitations of the P-38 and P-47 had nothing to do with the development of the Merlin powered Mustang. The problems and limitations of those two aircraft did have a lot to do with the selection of the Merlin powered P-51 as the "standard" long range escort fighter in the Spring of 1944.

 

[gjs238]

Uh, I thought that's what I said.
Guess if I were a diplomat I'd end up starting a war
Edit: But the chronolgy is appreciated!
Edit again: I still suspect the P-51B could have entered service sooner if it had received greater support.

 

[Jabberwocky]

The earliest P-47s could hold 305 US gallons (254imp) which means it held about 3 times the fuel of an early Spitfire or 109. It was also quite possible to cruise a P-47 for almost 900 miles as long as you stayed under 12,000ft and under 200mph indicated airspeed. Which was better than either of those two fighters could do.

Initial USAAF experience with early P-47Cs led to a tactical recommendation that they avoid contact with Luftwaffe single seaters below 16,000 ft. The lighter, nimbler Fw 190 and Bf 109 are at their best here. The P-47's major advantage is its power at altitude, granting it better comparative maneuverability and performance, particularly against the Fw 190, which was somewhat asthmatic at altitude.

Flying low and slow puts the P-47 at a significant initial energy disadvantage, a significant performance disadvantage and a significant tactical disadvantage. It also dramatically eases the intercept equation for the Luftwaffe, as well as putting the fighters right in the middle of the 8.8 cm flak envelope and towards the upper end of the 3.7 cm flak effective envelope.

Its a recipe for disaster.

 

[renrich]

All the AAf had to do to procure a longer ranged fighter than the P47 in 1942-43 was to direct an aircraft manufacturer to build the F4U1 ( with 361 gallons of internal fuel) for an escort fighter. With weight losses for no tail hook and no folding wings and with drop tanks it would have done nicely until the Merlin Mustang came along.

 

[Shortround6]

Please put the last two post together.

When I pointed out the almost 900 mile range of the P-47 it was to compare it to the Spitfire I or II which could manage about 500-575 miles at 195-210 mph depending on altitude. Or the 109E which was good for about 410 miles at a similar 200-220mph speed between 6,000 and 22,000ft These I believe are true airspeeds not the indicated of the P-47 which should be a bit faster. ALL of THESE cruise conditions are equally USELESS in a combat zone. The point I was trying to make was that the P-47 did have substantially more range than a number of other fighters when it was designed. Unfortunately this comparatively long range for a fighter was nowhere near what was needed to escort 4 engine bombers.

The F4U-1 wouldn't have done much better than the P-47 because most of the published range figures for it use similarly unrealistic (for European conditions) cruise conditions. Like 178mph at 5000-5500ft. It is quite possible that the F4U-1 engine was only using 42 gals an hour at that speed/altitude. Tremendous range but absolutely useless over Europe for escorting bombers.
At 26,000ft the Corsair needed 82 gal an hour to make 950hp while the P-47 used 105 gallons an hour to make 1200hp at 25,000ft. 11.58hp/gal/hr vs 11.42hp/gal/hr. We know that the P-47 had about 3/4 the profile drag of a Corsair but we may not know the induced drag or parasitic drag.
I am just not seeing the huge advantage in using the Corsair as a high altitude bomber escort in Europe however useful it may have been in other duties in other theaters.

 

[davebender]

Everything I have read suggests the Corsair was superior to the P-47 for both aerial combat and ground attack. Isn't that reason enough?

The F4U airframe was almost as large as the P-47. I suspect engineers could find room for huge internal fuel tanks just as they did for the P-47D-15.

 

[Shortround6]

Everything I have read suggests the Corsair was superior to the P-47 for both aerial combat and ground attack. Isn't that reason enough?

At what altitude?

If the 109s and 190s are climbing above the bomber formations and diving down on them and the bomber formations are at 20-25,000ft meaning the Germans are starting at 25,000-30,000ft (or higher) having the best aerial combat fighter in the world at 10-20,000ft doesn't do much good for bomber escort. Sure you can kill the German interceptors AFTER they complete firing passes on the bombers and eventually you can kill enough of them so that future bombing raids suffer low attrition but you use up a lot of bombers and their crews as bait in the meantime.
I may be exaggerating a bit but the P-47s area of strength was from 20,000ft up and the higher you went the more advantage it had. All but the earliest ones had at least 2000hp on tap at 25,000ft. The Corsair had 1650Hp at 22,000ft. Later P-47Ds could carry 2000hp to 30,000ft. Corsairs didn't see a whole lot of high altitude power increase until the F4U-4 which was a little late for European use.

 

[Lighthunmust]

At what altitude?

If the 109s and 190s are climbing above the bomber formations and diving down on them and the bomber formations are at 20-25,000ft meaning the Germans are starting at 25,000-30,000ft (or higher) having the best aerial combat fighter in the world at 10-20,000ft doesn't do much good for bomber escort. Sure you can kill the German interceptors AFTER they complete firing passes on the bombers and eventually you can kill enough of them so that future bombing raids suffer low attrition but you use up a lot of bombers and their crews as bait in the meantime.
I may be exaggerating a bit but the P-47s area of strength was from 20,000ft up and the higher you went the more advantage it had. All but the earliest ones had at least 2000hp on tap at 25,000ft. The Corsair had 1650Hp at 22,000ft. Later P-47Ds could carry 2000hp to 30,000ft. Corsairs didn't see a whole lot of high altitude power increase until the F4U-4 which was a little late for European use.

Shortround6 you appear to have an excellent understanding of and access to data on the factors involved in aircraft performance and tactics for air battle over WW2 Europe. I have in my library some of the best books ever written about some of the aircraft we all have been talking about. You have really convinced me to get them out and do some research. I'll get back to you and the thread after that. Until then, I still think that a P-47 with more internal fuel and of course adequate drop tanks would have enough performance to successfully defend the bombers. I also think that in doing so many more P-47s would have made it home with pilots able to fight again than in the P-51. Even with all the initial problems the P-47s had they still allowed rookie american fighter pilots to hold there own against the experienced pilots of the Luftwaffe and begin to prevail.

 

[davparlr]

The F4U-1D(W) was a pretty good performer up to about 30k, similar to the P-51B(pulling 67") at low altitude, not as good at high altitude. P-47 was better at high altitude. It compared favorably with axis fighters of the time from SL to 30k up to fall, '44. Did not have the range any more with the removal of wing tanks.

 

[tomo pauk]

The issue with water-injection for F4U/P-47 was availability - early 1944, IIRC.

Our beloved Jug really needed some wing drop tanks, at least 300 gal total, and such gear was available for P-38 in 1942. So there were no feasibility issues for 1943 (by that time P-38 carried 600 gal max, (for ferry purposes?)). The other possibility is a rear fuselage drop tank, like P-51s received in late 1943. With at least 75 gals under belly, that would've mean 680 gals + what rear tank holds (70-150 gals, depending how the CoG shift is experienced).

 

[davparlr]

The issue with water-injection for F4U/P-47 was availability - early 1944, IIRC.

You remember correctly

Our beloved Jug really needed some wing drop tanks, at least 300 gal total, and such gear was available for P-38 in 1942. So there were no feasibility issues for 1943 (by that time P-38 carried 600 gal max, (for ferry purposes?)). The other possibility is a rear fuselage drop tank, like P-51s received in late 1943. With at least 75 gals under belly, that would've mean 680 gals + what rear tank holds (70-150 gals, depending how the CoG shift is experienced).

It also needs more internal fuel. Once engaged with the enemy the drop tanks are, well, dropped. So you have to do combat and return home on internal fuel. 305 gallons was not enough to be effective and that is only if you go home low and slow.

 

[Shortround6]

Rear tanks were apparently tried and quickly dropped from consideration. This was a field modification in the South Pacific. All during 1943 there was a mad scramble to extend the range of the P-47 using an amazing variety of drop tanks. Single 200gal paper tanks under the fuselage, 110 gal P-40/P-39 tanks (?), British cylindrical reinforced paper tanks(capacity not given) 2 165 gal P-38 tanks for cross Atlantic ferry, 75/85 gal metal tear drop tanks. 108 gal British tanks in both paper and metal, and 150 gal metal belly tanks.
ALL before Nov 1943 when water injection began to be fitted.
It is May of 1944 when the XP-47N is first ordered. Maybe it could have been ordered in the late summer/early fall of 1943 and gotten into service in the spring/summer of 1944 with a lower powered engine than was finally used. One with 2300-2600hp WER instead of 2800hp. Asking for P-47N fuel capacity and range in 1940-42 was probably too much for the early 2000hp engines. Not only did engine power go up but runway lengths were getting longer all the time. Long range aircraft don't do any good if they can't get of the ground with a full load of fuel.