WHAT IF: Longer range P-47 from start

[Lighthunmust]

A P-47 N weighed 1100lbs more than a P-47C when both were empty. It could hold another 250 gallons of fuel, that is another 1500lbs. Your clean but full 12500lb P-47 is now up to 15,100lbs (a 20.8% increase) with no increase in power and still has the toothpick prop.

I don't doubt your numbers, but more efficient props would still have soon been available. Much of that extra fuel weight would have been gone by the time they were deep into Germany. Even with the extra weight the energy management tactics used for the 47 would be successful, especially against the 109s and 190s weighted down with extra armor and arms to bring down the 17s and 24s.

 

[gjs238]

Early P-47s (P-47B and P-47C) had teething problems of their own. Early P-47s were lacking in performance, especially climb and acceleration. Both aircraft were relatively expensive with the single engine P-47 costing almost as much as a twin engine P-38.

IMO the P-38 has the potential to develop into a decent long range bomber escort by early 1943, exactly when such an aircraft was needed by the U.S. 8th Air Force. The P-47 does not.

Better yet, the U.S. Army Air Corps should purchase the Fw-187 tooling from Focke Wulf during 1939. Power it with a pair of Packard built Merlin engines.

Yes, I agree, the idea of a reliable P-38 for 8th AF escort is tantalizing, and we've discussed in other threads.
But it didn't happen (at least not until after the P-51 had established itself in this role.)
What stopped the P-47 from fulfilling this role? Range.

 

[davparlr]

The early P-47s, the B, C, and early Ds, performed quite well at bomber altitudes, 20-25k, and above with good speed, dive and zoom. And, with powerful armament, they could have provided good cover for the bombers as escorts. To provide adequate range, the internal fuel of the P-47 would have to be around 350 gallons, ala F4U-1. I believe this could be done, and was done later, without wing tanks. Also, adequate drop tanks would have to be provided. This should have allowed the early P-47s to have a similar range and combat time as the P-51B/D. I think it is too bad, and very sad, that the Army stuck to the concept of self-defending bombers as long as it did. Many died. If the P-38 had matured and the early P-47s were made escort capable, the P-51 would still have move in. It was just too easy to fly well and too cheap to manufacture, and it was still very fast at lower altitude relative to the other two fighters and enemy aircraft.

 

[Lighthunmust]

"If the P-38 had matured and the early P-47s were made escort capable, the P-51 would still have move in. It was just too easy to fly well and too cheap to manufacture, and it was still very fast at lower altitude relative to the other two fighters and enemy aircraft."

I am not so sure anyone would have pushed to put a Merlin in a Mustang if the P-47 had the range. Your definitely right about the low altitude speed and manufacturing costs, but the P-47 was more forgiving to fly and less likely to kill you if you crashed. If a weapon is working for you most users are loath to risk change.

 

[gjs238]

P-47 with endurance, together with the P-38, would be the long range, high altitude machines.
P-51 w/Allison could replace the P-40, with P-40 production ending earlier than it historically did.
No need to pay royalties to R/R.

Under those circumstances, one could certainly make the argument that a Merlin P-51, despite the royalties, may be cheaper than the P-38 or P-47.
But if American technology is doing the job, and doing the job well, others may very well argue against a Merlin P-51.

 

[Shortround6]

I don't doubt your numbers, but more efficient props would still have soon been available. Much of that extra fuel weight would have been gone by the time they were deep into Germany. Even with the extra weight the energy management tactics used for the 47 would be successful, especially against the 109s and 190s weighted down with extra armor and arms to bring down the 17s and 24s.

1. the first 733 P-47s were ordered in sept 1940. the more efficient propellers aren't fitted until Dec of 1943.
2. You need some of the extra fuel weight to get back out of Germany. P-47Ds with 305 gallon fuselage tanks and 300gallons in under wing tanks were credited with a 425mile combat radius at 25,000ft. with the 370 gallon fuselage tank and 300 gals under wing the radius went about 600 miles. P-47Ns with 556 gals of internal fuel had a radius of 400 miles. They got to a P-51 beating 1000mile radius by carrying 440 gals in external tanks for total of of 996 gals of fuel.
An early P-47 gets about 2 miles to the gallon at 337mph at 25,000ft. It is just under 600miles from Berlin to London. How much reserve do you want and is 337mph a fast enough cruise. Prevailing winds come from the west. Your 5 minute WE rating and 15-20 minutes of military power will probably come after the drop tanks are gone. 15 minutes of Military power (2000hp) is about 69 gallons of fuel.

 

[Lighthunmust]

1. the first 733 P-47s were ordered in sept 1940. the more efficient propellers aren't fitted until Dec of 1943.
2. You need some of the extra fuel weight to get back out of Germany. P-47Ds with 305 gallon fuselage tanks and 300gallons in under wing tanks were credited with a 425mile combat radius at 25,000ft. with the 370 gallon fuselage tank and 300 gals under wing the radius went about 600 miles. P-47Ns with 556 gals of internal fuel had a radius of 400 miles. They got to a P-51 beating 1000mile radius by carrying 440 gals in external tanks for total of of 996 gals of fuel.
An early P-47 gets about 2 miles to the gallon at 337mph at 25,000ft. It is just under 600miles from Berlin to London. How much reserve do you want and is 337mph a fast enough cruise. Prevailing winds come from the west. Your 5 minute WE rating and 15-20 minutes of military power will probably come after the drop tanks are gone. 15 minutes of Military power (2000hp) is about 69 gallons of fuel.

Is your point that your data indicates a P-47C/D with the internal and external fuel load of a P-47N could not get the job done of successfully defending the bombers? Do you have similar data for a P-51 that indicates it had significantly greater ability to defend the bombers due to fuel load and performance?

I think a P-47C/D with "N" fuel capacity may have been good enough to have resulted in no one pushing for a Merlin powered Mustang. My opinion is based on the criteria I listed in the thread I started today. If I am wrong, please take the time to explain why. Thank you.

 

[davebender]

The P-38 program began during February 1937. The U.S. Army Air Corps have 6 years (until early 1943) to perfect the aircraft for use as a long range escort. More time than was required to build an atomic bomb from scratch.

With adequate resources and good program management there is no reason the P-38 cannot be perfected by early 1943. If need be we can design and perfect an entirely new aircraft engine in 6 years. Just as Germany designed and perfected an entirely new aircraft engine (BMW801 radial) for the Fw-190.

 

[Shortround6]

Is your point that your data indicates a P-47C/D with the internal and external fuel load of a P-47N could not get the job done of successfully defending the bombers? Do you have similar data for a P-51 that indicates it had significantly greater ability to defend the bombers due to fuel load and performance?

I think a P-47C/D with "N" fuel capacity may have been good enough to have resulted in no one pushing for a Merlin powered Mustang. My opinion is based on the criteria I listed in the thread I started today. If I am wrong, please take the time to explain why. Thank you.

The Start of this thread was "What if the USAAC, recognizing the historically expeditionary nature of the US military, and the need to reach out to the enemy rather that wait for the enemy to come to you, had specified "P-51 like" ranges in fighters such as the P-40 and P-47?"
Now maybe I misinterpreted it But I took that to mean 'what if the USAAC had specified the longer range either at the beginning of the P-47 development or in the earliest stages of the P-40s development'. Changing specification too much in the middle of production leads to changes in tooling and lost production that many countries were hesitant to do.
I do not have the full specifications or requirements that the P-47 was designed to. These would include not only top speed, ceiling, desired climb rate or time to altitude, range and armament but things like landing speed and field length "G" loading strength and landing "G" load requirements among others. Some of this can be traded back and forth on paper while the plane is in the proposal stage before contracts are signed with performance guarantees. Curtiss lost over $14,000 in penalties on the XP-46 contract because the prototype would not perform up to contract specifications. The Army may relax some of these requirements once a plane is in service, like adding the rear fuselage tanks to the P-51, rather than call for a new design, but while a plane is still on paper or in prototype trials they are going to want it to meet the specifications (or mutually agreed modifications).
Adding hundreds of pounds of tanks and fuel, even if you can find room, will impact not only field length and climb, but those stress requirements.
If we are talking about specifying the extra range/fuel from the beginning, I am pointing out that the power plant (engine and propeller) available or planned was not capable of the performance not only of the real the P-47N engine and propeller of late 1944/45 but even of the field modified "D"s of the end of 1943.

Once again for an Idea of the performance "hit" the plane would take see this chart: http://www.zenoswarbirdvideos.com/Images/P-47/47TOCL.gif

Look at the climb rates for the different weights. Please look at the notes, like this is for O degrees Celsius and add 10% to climb times for each 10 degrees above O degrees. Also note that after 5 minutes at military power the engine is throttled back to "normal" power which is 1625hp instead of 2000hp so a lot of the climb figures are not true combat figures but you can still get an idea of the performance "hit" of the extra weight.
Drop tanks helped designers out because they could increase range while not hurting performance at short range like a bigger airframe/ heavier internal tanks would. But the planes "Combat radius" is limited to how far the plane can fly after dropping the tanks, engaging in combat and then flying home with enough reserves to handle weather conditions and minor navigation errors.
Please note that the later P-47Ds had 15-25% more power available than the "B" and "C" versions to handle not only the drop tanks but the change from 305 to 370 gals of internal fuel. P-47s sometimes used their water injection for take-off while carrying heavy loads from short airstrips in hot conditions.
When building fighter aircraft it helps if the "balance" is not tipped too far to one side or the other. A long range fighter for escort use is great, as long as it can actually fight once it gets there or can fight near it's own home base if the situation changes.

 

[gjs238]

The P-38 program began during February 1937. The U.S. Army Air Corps have 6 years (until early 1943) to perfect the aircraft for use as a long range escort. More time than was required to build an atomic bomb from scratch.

With adequate resources and good program management there is no reason the P-38 cannot be perfected by early 1943. If need be we can design and perfect an entirely new aircraft engine in 6 years. Just as Germany designed and perfected an entirely new aircraft engine (BMW801 radial) for the Fw-190.

The reason I titled this thread P-47 was that I sorta gave up in frustration on the P-38
But you are entirely correct. There was plenty of time to iron out the bugs in the P-38.
A reliable P-38 obviates the need for a long range P-47 or a Merlin P-51.
But that's been hashed over in other threads

 

[Shortround6]

The P-38 program began during February 1937. The U.S. Army Air Corps have 6 years (until early 1943) to perfect the aircraft for use as a long range escort. More time than was required to build an atomic bomb from scratch.

With adequate resources and good program management there is no reason the P-38 cannot be perfected by early 1943. If need be we can design and perfect an entirely new aircraft engine in 6 years. Just as Germany designed and perfected an entirely new aircraft engine (BMW801 radial) for the Fw-190.

Rather different amounts of funding for the different projects. and for the 2 aircraft engines rather different goals and results. You want to revise history so the US was spending massive amounts of money on engine development before the war even starts in Europe. You are also confusing engine development with turbocharger development with aircraft development. There was nothing particularly wrong with the Allison engine itself so lots more money/effort wouldn't have done much there. There was a problem with the turbo controls which were a government supplied component just like the turbo charger. The Government contracted with GE for the turbos (and the controls?) although the controls were to a government (army design) and supplied both the engines and and turbos/equipment to Lockheed for installation. This was a recipe for trouble as nobody but the government was actually responsible for the total package and the government didn't have enough engineers/test facilities for proper trouble shooting/development.
I would note that it took the Germasn a bit over 6 years to get a turbo BMW801 of any sort into the air and we have no idea of how it would have performed in service.

 

[Shortround6]

The reason I titled this thread P-47 was that I sorta gave up in frustration on the P-38
But you are entirely correct. There was plenty of time to iron out the bugs in the P-38.
A reliable P-38 obviates the need for a long range P-47 or a Merlin P-51.
But that's been hashed over in other threads

The P-38 had not been tried out as a long range escort before the decision to install the the Merlin in the P-51 was made. The P-38 was only really being tried out as a bomber escort in the fall of 1943 at which time the Contract had already placed for Merlin Mustangs, deliveries started and squadrons started working up. The decision as to which fighter to 'standardize' as the 8th AF bomber escort had not been made but Merlin Mustangs were going to be made no matter what that decision was.

 

[davparlr]

I am not so sure anyone would have pushed to put a Merlin in a Mustang if the P-47 had the range. Your definitely right about the low altitude speed and manufacturing costs, but the P-47 was more forgiving to fly and less likely to kill you if you crashed. If a weapon is working for you most users are loath to risk change.

The first P-51 with an installed Merlin flew in November, 1942, or about the same time the P-47s went operational in Europe, and long before the AAF recognized the need for a long range escort. The Brits were also involved with the Merlin powered P-51 and flew one even earlier, October, 1942, they were not even interested in long range escort only a superb figther. Both AFs recognized the revolutionary aerodynamics, for 1941, of the P-51 and wanted a better engine. When the Merlin was flown in the P-51, I am sure the comments were OMG! From then own, nothing would stop the P-51.

 

[gjs238]

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

 

[davebender]

revise history so the US was spending massive amounts of money on engine development before the war even starts in Europe.

Battleship Photo Index BB-55 USS North Carolina
Oct 1937. BB North Carolina laid down.
June 1938. BB Washington laid down.
July 1939. BB South Dakota laid down.
July 1939. BB Massachusetts laid down.
Nov 1939. BB Indiana laid down.
Feb 1940. BB Alabama laid down.

The US was spending massive amounts of money on military hardware from 1937 onward. Why not fund development of something we really needed such as a state of the art V12 aircraft engine?

 

[gjs238]

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

 

[davebender]

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.

 

[gjs238]

Or the P-39 P-40 for that matter.

 

[davparlr]

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

They certainly had with the turboless P-38s, but I do not think they had much experience with the P-47. The Brits were really interested in the performance improvements of the already fast P-51A. In April,1942, the RAF asked RR test pilot Hawker to evaluate the Mustang I. His comments were that he could not think of a single improvement other than putting in the Merlin (surprise!). Again, they were looking for a superior fighter, not an escort. The P-51 was suppose to replace the P-40. It did far more than that. This all occurred independently of the P-38/47 issues.

 

[gjs238]

I agree.
In other threads I tried exploring the potential of earlier/faster P-51 development/deployment.
It seems the USAAC dragged their heels.