I have the following range setting for P-38, P-47 & P-51 fighters from a series of official USAAF test reports between March & June 1945 for the "Escort a B-29 formation within 300-miles of Japan flight" flight regime.
This regime escorted B-29 1/2 hour both to the target and leaving, w/20-min full military power in this "magic escort hour".
The B-29 escort flight regime incorporates 400 or more miles at optimum fuel conserving power setting below 20,000 ft, AKA the "Fuel lean, low engine RPM, low Prop RPM" settings Charles Lindberg pioneered for the 5th Air Force P-38's in early 1944.
1. P-38J-25 & P-38L
825 mile combat radius at 25,000 feet
1635 total air miles
1650 ground miles
425 Gal internal fuel
330 Gal External fuel (2x165 Gal tank)
Fuel Consumed 705 Gal
Fuel Reserve 50 Gal (45 Min)
2. P-47D-25
800-mile radius of action
Full internal full
330 Gal external fuel (2x165 gal drop tanks)
3. P-47N
900-mile radius of action
Full Internal Fuel
330 Gal External fuel (2x165 gal external tank)
1050-mile radius of action
Full Internal Fuel
440 Gal External fuel (2x165 gal and one 110 Gal external tank)
1100-mile radius of action
Full internal fuel
630 Gal external fuel (2x310 gal drop tanks overloaded by 5-gal ea.)
4. P-51D-20
800-mile radius of action
Full internal fuel
150 Gal External fuel (2x75 gal drop tanks)
850-mile radius of action
Full internal fuel
200 Gal External fuel (2x100 gal drop tanks)
With the replacement of one 165-gal tank with a 300-gal tank, a P-38L could reach 950-miles in the B-29 escort regime, but like the Zero fighter at Guadalcanal, it had to keep thje 165-gal fuel tank to get back.
The P-47N with two 300 gallon tanks or two 165 gallon and one 100 gallon tank outranged a P-51D with two 100 gallon tanks.
The P-51H could carry two 165 gallon tanks into combat, but it lacked the large 85-gal central tank of a P-51D, so had the same 850-mile range as the P-51D.
The folks at North American wanted to change that per the folowing:
HEADQUARTERS, ARMY AIR FORCES
WASHINGTON
4 April 1945
MEMORANDUM FOR CHIEF, REQUIREMENTS DIVISION
SUBJECT: Fighter Cover for VLR Operations
[snip]
f. An automatic pilot will be in the P-47N's and subsequently in the P-51H.
[snip]
2. For your further information, the following projects are underway:
a. Installation of a Hammock Seat, a device which is hoped will materially lesson pilot fatigue.
b. Installation of thermos type containers for liquid nourishment.
c. Installation of an Anti-G suit with a valve which provides pulsation pressure (this provides massaging action to alleviate fatigue).
d. Collapsable rudder pedals which will enable the pilot to stretch his legs are being incorporated on all production P-47N's.
e. Under procurement from the Navy is a navigational computer used by Navy fighter pilots. This item was requested by the 301st Wing, and a basis of issue of one per pilot for that Wing has been requested.
f. Two (2) of the first seven (7) P-51H's are being modified to carry 305 gallons internal fuel. This is accomplished by increasing the capacity of the fuselage tank from 50 to 100 gallons. North American Aviation thinks that this aircraft, so modified, will be better balanced with respect to the CG than the present "D" series which incorporates the 85 gallon fuselage tank. This will give the airplane a radius of approximately 1400 miles, and if tests prove satisfactory, it is possible that all future P-51H's will be so modified.
S/
HENRY VICCELLIO
Colonel, Air Corps
Chief, Fighter & Air Defense Branch
Which would have pushed the range of the P-51H w/2 ea 165-gal tanks to 950 miles of the P-38L with a 300-gal plus 165-gal external tankage.
This 100-gal internal tankage P-51H would not have arrived in time for Operation Olympic in Nov 1945.