The P-47 already had those fuel lines, if I recall.
I also recall that the US did not use drop tanks in Europe during the summer of 43. If the P-47 could use them, and it gave them the range needed for escort, why not use them?
The P-47C-2 & Subs were plumbed for C/L ferry tanks. The first missions using Ferry tanks were in latter days of Blitz Week in July 1943, using the 200gal 'tub' tank, which was not pressurized and would not feed from slaved vacuum pump above 18000 feet. Consequently it was only filled w/100 gal and extremely draggy. The reason 'why not' use them were a.) non sealed bomb carried into combat, b.) had the equivalent drag of 2x110 gal SS tanks delivered in September, 3,) were dangerous when ejected. LtC Cass Hough caused to be installed a wood 'horizontal fin' on the 200 gal tank to force it downward when ejected.
The straight line combat radius boost was about 75mi - the result = cross the German/Dutch border (barely) on a straight line, but not out of France on a course to Schwenfurt.
So,
yes the 8th AF
did use the 200gal in July, the new 75 gal combat tank in August (still could not get out of France during Schweinfurt-Regensburg mission) and the 110 gal combat tank in September - Summer of 1943.
The
PROBLEM for the P-47C and D through the P-47D-11 series was that the capability to hang fuel tanks on the wing was problematic for three reasons. 1.) The wing was not stressed to carry even 500 pounds under the wing, 2.) the wing did not have either a pylon or a fuel transfer system of plumbing to transfer fuel from external rack to engine, and 3.) while a 'doable' Depot Level Mod, it was far too labor and time intensive to remove the wings, remove the skin, install the plumbing, install the necessary doublers for the spars, re-skin the wing, install the pylons - IIRC only 50+ were so converted before the -15/-16 arrived in Feb/March 1944.
Exascerbating the
PROBLEM (and Greg's lack of understanding) was that during escort the Penetration and Withdrawal Escort, the ony stright line cruise was to/from the R/V or Break Escort waypoint - from that point forward, the P-47C/D is burning fuel at optimal cruise - but not in a straight line as they were tethered to the B-17 formation straight line speed. They are going fast enough to go farther on a straight line, but slow marching while weaving and 'essing' to keep pace with the bombers.
Further, Greg failed to understand the difference between Ferry calculations and Combat Radius calculations - also tested by Wright Field to develop Operating Manual.
8th AF SOP included warm up and taxi time for approximately 50 ships including spares, take off at METO in pairs (usually), climb to 3000 feet - using internal fuel, switch to externals and begin the squadron assembly from elements to flights to squadron, then repeat two times during orbit at Max Continuous Power, then climb to cruise altitude where power and RPM were reduced to cruise settings (if on time to make R/V per schedule).
Extracted from various flight test data aswell as published Wright Field documents, the 'average' fuel consumption for the P-47 R-2800 at varius MP and RPM for each stage is APPROXIMATELY
With 75 gal C/L tank
113 gal for warm up, taxi, climb to altitude (no formation consumption), begin cruise
40 gal for reserve
90 gal for 20 min combat (15min MP, 5 min WEP)
305+75 gal at Engine Start =380gal
380-243=137gal available for straight line cruise.
So optimally that P-47, independent of slowing down to effective 210mph TAS to escort bombers, at 85+ gph cruise consumption has 137/85 = 1.6 hours of total cruise time left to escort bombers and return home. The escort Effective airspeed is 210, the return after break escort and ejecting tank is closer to 300mph TAS.
The Bomb Division ops co-ordinates target info, take off times, R/V times and waypoint for escorts, etc via Frag Orders to Fighter Wings
The mission planner (Div Ops) then has to adjust the straight line example above (which BTW is not a Precision calculation) for weather, winds aloft, the true linear distance of a course with course changes while escorting, the amount of time to takeoff and form up the group.
The Fighter WingOps is performing the same calcs as it makes assignments for each group (Penetration, Withdawal, Sweep) to determine R/V and B/E waypoints -
The Fighter Gp Ops gets the Frag Order with target, R/V, B/E, Bomb Wing assignment, etc and baks out Start Engine times to accomdate estimates to get to R/V on time.
After all these deliberations, the Gp CO at briefing may caution the fighter pilots to intercept and return - do not chase, because of probable headwinds on course, or stretched escort time before B/E, or forecast weather and visibility expected upon return to base. etc, etc. All designed to ensure as much as possible fuel available for a safe return.
Summary - Greg was CORRECT, the P-47 COULD have gone to Schweinfurt BUT - everybody dies or is taken prisoner due to fuel starvation near the German/France border.