From: jfb@ihlpl.att.com
Subject: Number Forty-Seven in the Series--Republic P-47 Thunderbolt (3 of 9)
Keywords: P-47D razorbacks and bubble-tops
Organization: AT&T Bell Laboratories -  Naperville, Illinois
Date: Tue, 26 Jan 1993 17:45:43 GMT


From jfb@ihlpl.att.com


The P-47D was the first version of the Thunderbolt to undergo really 
large-scale production.  The first USAAF order for the P-47D took 
place on October 14, 1942, when 850 examples were ordered.  However, 
it was to be followed by many, many more.  

In its initial form, the P-47D differed very little from the 
P-47C-5-RE which preceded it on the Farmingdale production lines.  The 
P-47D had some changes in the turbosupercharger exhaust system which 
incorporated an adjustable duct and redesigned vents for the engine 
accessory section.  More extensive armor protection was provided for 
the pilot.  Generally, however, early P-47Ds can be distinguished from 
Cs only by their serial numbers.  

Demand for the Thunderbolt was so great that Republic built a new 
factory at Evansville, Indiana to augment production of the P-47D.  
1050 P-47Ds were ordered from Evansville on January 31, 1942, and the 
first Evansville-built P-47D rolled off the assembly line in September 
of 1942.  

Following cancellation of the Army contract for the P-60A in January 
1942, the Curtiss-Wright company was given a contract to begin 
construction of the D-version of the Thunderbolt under license at its 
Buffalo plant.  The Curtiss-Wright built version was designated P-47G.  
The first delivery of a P-47G took place in December of 1942.  The 
first 20 P-47Gs produced by Curtiss (P-47G-CU) were similar to the 
concurrent P-47C, but the remainder were similar to Republic-built 
P-47Ds.  Curtiss produced a total of 354 P-47G-1-CU through 
P-47G-15-CU Thunderbolts by March of 1944, these planes being 
identical to Republic-built P-47Ds.  They could be distinguished from 
Republic-built Thunderbolts only by their serial numbers.  

All early Thunderbolts used the R-2800-21 engine, but water injection 
capability was added beginning with the D-3-RA and D-5-RE production 
blocks.  In the D-5 to D-10 blocks, the pilot manually controlled the 
water flow of the injector, but the injection procedure was automatic 
on the D-12 and subsequent blocks.  

Shackles for a belly tank or a 500-pound bomb were added to P-47D-4-RA 
and later blocks.  

Drop tanks under the wings were introduced on the D-15-RA and D-16-RE, 
along with the more powerful R-2800-63 engine.  

Two Curtiss-built P-47Gs were converted as tandem, two-seat trainers.  
One of the fuselage fuel tanks was removed and a second cockpit was 
fitted in its place.  Known as the TP-47G, these aircraft retained the 
eight-gun armament of the single-seat version.  

Toward the end of 1943, Eighth Air Force Thunderbolts began returning 
from escort missions over the Continent "on the deck", seeking out 
enemy ground targets of opportunity for their unused ammunition as 
they made their way back to the Channel.  Somewhat surprisingly, it 
was found that the Thunderbolt was rather well-suited for this new 
role.  This led to perhaps the most successful adaptation of the 
Thunderbolt--as a fighter-bomber.  

The P-47D-6-RE to P-47D-11-RE and P-47G-10-CU to 15-CU production 
blocks had only ventral shackles, which were stressed to accommodate 
one 500-lb bomb, but subsequent production blocks were fitted with 
underwing pylons and stronger wings which permitted them to carry two 
1000-lb bombs, three 500-lb bombs or a combination of bombs and drop 
tanks.  Either six or eight machine guns could be carried, and maximum 
ammunition capacity was 425 rpg.  However with the full ordinance 
load, ammunition capacity was reduced to 267 rpg.  

At about this time, a number of Thunderbolts suffered mysterious 
engine failures during missions over the Continent that could not be 
ascribed to enemy action.  It was eventually discovered that the 
additional weight of the bombs and drop-tanks added so much weight to 
the aircraft that the Thunderbolt was able to build up 
excessively-high speeds during bombing attacks.  During the recovery 
from these high-speed dives, g-forces got so high that a surge or 
vapor lock was produced in the fuel lines which the fuel pump was 
unable to overcome.  

Production batches from the P-47D-20-RE onward were fitted with a 
"universal" wing which could carry a variety of drop tanks or bombs.  
These batches also introduced the R-2800-59 or -63 engine with an 
increased war emergency power of 2535 hp.  Beginning with blocks 
D-22-RE and D-23-RA, a larger (13-foot diameter) paddle-bladed 
propeller was fitted to accommodate this increased power.  It added 
400 feet per minute to the climb rate, but during landings and 
takeoffs there was only a scant six inches of clearance between blade 
tips and the ground.  Takeoffs and landings must have both been 
hair-raising.  

Blocks D-22-RE and D-23-RA were also provided with a jettisonable 
cockpit canopy which was activated by the pilot pulling a ring.  The 
hood would then be pushed backward, and the force of the slipstream 
would then do the rest of the job of pulling the canopy free of the 
aircraft.  A bullet-proof windshield was fitted, and internal fuel 
capacity was increased.  

The 3962 P-47D-1RE to -22-RE Farmingdale-built Thunderbolts, the 1461 
P-47D-2-RA to -23-RA Evansville-built Thunderbolts, and the entire lot 
of 354 P-47G-1-CU through P-47G-15-CU Curtiss-built Thunderbolts all 
had the original framed sliding canopy that was first used on the 
P-47B.  However, combat experience indicated that the the rear 
fuselage decking on these Thunderbolts provided a serious blind spot 
aft which was a real hindrance in air-to-air battles.  In an attempt 
to improve rearward visibility, a few P-47Ds were fitted in the field 
with the RAF "Malcolm hood", a Spitfire-like bubble canopy made in 
England which was made famous by its application to the P-51B and C 
Mustangs flown by both the RAF and USAAF.  However, P-47Ds fitted with 
Malcolm hoods were quite rare, whereas P-51Bs and Cs with Malcolm 
hoods were quite common.  

In the meantime, in search of a more lasting solution the USAAF fitted 
a standard P-47D-5-RE airframe (serial number 42-8702) with a bubble 
canopy taken from a Hawker Typhoon.  In order to accommodate the 
bubble canopy, the Republic design team had to cut down the rear 
fuselage.  This conversion was redesignated XP-47K, and was tested in 
July 1943.  This modification was immediately proven to be feasible, 
and was promptly introduced on both the Farmingdale and Evansville 
production lines.  

Ordinarily, the USAAF would have given such a radical modification as 
that which produced the bubble-canopy Thunderbolt a completely new 
variant letter (or perhaps even a new type number).  However, the 
USAAF chose instead to designate it simply by giving it a new 
production block number in the D-series.  Consequently, the first 
batches to feature this new bubble canopy were Farmingdale's 
P-47D-25-RE and Evansville's P-47D-26-RA.  These batches also had the 
R-2800-59 or -63 engines, the paddle-bladed propeller, and the 
"universal" wing first introduced on the "razor-back" P-47D-20-RE.  
Stronger belly shackles capable of carrying a 91.6 Imp.  gall.  drop 
tank were fitted.  This tank, together with the 170.6 Imp.  gall.  
main fuselage tank, an 83-gallon auxiliary fuel tank and two 
125-gallon underwing tanks, made it possible to carry a total fuel 
load of 595 Imp.  gall, providing a maximum range of 1800 miles at 195 
mph at 10,000 feet.  

A single P-47D-20-RE (serial number 42-76614) was taken off the 
production line and modified as XP-47L with a bubble canopy as in the 
XP-47K and with increased capacity fuel tanks which raised internal 
fuel capacity from 305 to 370 US gallons.  Both of these changes were 
incorporated in the P-47D-25-RE production batch.  

The early "bubble-canopy" Thunderbolts had suffered from some 
directional instability as a result of the loss of aft keel area.  
>From the P-47D-27-RE production lots onward, a dorsal fin was fitted 
just ahead of the rudder.  This innovation successfully restored the 
stability.  

Underwing zero-length launching stubs for a total of ten five-inch 
HVAR rockets were fitted to Thunderbolts from production blocks 
P-47D-30-RA onward.  

The high diving speeds of which the Thunderbolt was capable pushed the 
aircraft into the edge of compressibility, and new blunt-nosed 
ailerons were fitted to improve controllability at these high speeds.  
In order to help in dive recovery at these high speeds, an 
electrically-operated dive recovery flap was fitted on the 
undersurfaces of each wing.  

Farmingdale produced a total of 2547 bubble-canopy P-47Ds and 
Evansville built 4632.  

The Royal Air Force was supplied with a total of 830 P-47Ds.  In RAF 
service, the "razorback" P-47D was known as the Thunderbolt I and the 
"bubble canopy" P-47D was known as Thunderbolt II.  Thunderbolt Is 
were delivered in two batches--serials FL731 to FL850 and HB962 to 
HD181.  They were delivered to the RAF from the P-47D-22-RE production 
blocks.  The "bubble-topped" Thunderbolt II fighters were from the 
P-47D-25/-30-RE and the P-47D-30/-40-RA production blocks, and four 
main batches were delivered--serials HD182 to HD301, KJ128 to KJ367, 
KL168 to KL347, and KL838 to KL976.  A few aircraft in the last two 
batches were equipped with the dorsal fin strake.  The RAF 
Thunderbolts were evaluated in Europe, but most of them were shipped 
to the CBI theatre, where they fought against the Japanese.  

The Soviet Union was allocated 203 P-47D-22-RE and 27-RE Thunderbolts 
under Lend-Lease, but only 196 actually reached their destination.  I 
have no information about their service.  

A total of 446 P-47Ds was supplied to the Free French forces during 
the war, and by V-E Day, they equipped two Escadres de Chasse.  They 
were replaced in service by De Havilland Vampire jets during 1951.  
Many of these French Thunderbolts were then transferred to Algeria, 
where they were used against the nationalist forces during the 
Algerian civil war.  They were finally phased out of service during 
1960, at about the same time that the French pulled out of Algeria.  

It is not widely known, but the Brazilian Air Force participated in 
combat on the Allied side on the Italian front in 1944.  A squadron of 
P-47Ds operated by Brazilian Air Force pilots was attached to the US 
Twelfth Air Force and went into action for the first time on November 
11, 1944.  Before the end of the war, the Brazilian Air Force had 
received 88 P-47Ds.  

The Mexican Air Force was equipped with 25 P-47D Thunderbolts during 
World War II, and the 201st Fighter Squadron of the Mexican Air Force 
was preparing to go overseas to serve alongside US forces in the South 
West Pacific when the Japanese capitulated.  Consequently, Mexican 
Thunderbolts never saw any action.  However, at least one of my sources
has Mexican units entering combat in the Philippines in early 1945.
Details, anyone?

During the immediate postwar years, numerous surplus ex-USAAF 
Thunderbolts were supplied to foreign air forces.  These included the 
air forces of Bolivia, Brazil, Chile, China, Colombia, Dominica, 
Ecuador, Honduras, Iran, Nicaragua, Peru, Turkey, Venezuela, and 
Yugoslavia.  Some of these foreign-operated Thunderbolts remained 
flying until the late 1960s until they were finally replaced by jet 
aircraft.  

A "razorback" P-47D is on display at the Champlin Fighter Museum at 
Mesa, Arizona.  A Thunderbolt is also on display at the WPAFB
museum, but I don't have any record of its serial number.

Specifications of the P-47D-25-RE: 

One Pratt and Whitney R-2800-59 Double Wasp eighteen-cylinder 
air-cooled radial, war emergency power of 2535 hp.  Maximum speed was 
429 mph at 30,000 feet, 406 mph at 20,000 feet, 375 mph at 10,000 
feet, 350 mph at sea level.  Initial climb rate was 2780 feet per 
minute.  Climb rate at 30,000 feet was 1575 feet per minute.  Service 
ceiling was 40,000 feet, and range was 950 miles at 10,000 feet.  
Range with maximum external fuel was 1800 miles at 10,000 feet at 195 
mph.  Weights were 10,700 pounds empty, 14,600 pounds normal loaded, 
and 17,500 pounds maximum.  Dimensions were wingspan 40 feet 9 3/8 
inches, length 36 feet 1 3/4 inches, height 14 feet 7 inches, and wing 
area 300 square feet.  

Serials of Republic-built P-47Ds: 

42-7853/7957 	Republic P-47D-1-RE Thunderbolt 
42-7958/8402 	Republic P-47D-2-RE Thunderbolt 
42-8403/8702 	Republic P-47D-5-RE Thunderbolt 
42-22250/22363  Republic P-47D-1-RA Thunderbolt 
42-22364/22563  Republic P-47D-2-RA Thunderbolt 
42-22564/22663  Republic P-47D-3-RA Thunderbolt 
42-22664/22863  Republic P-47D-4-RA Thunderbolt 
42-22864/23113  Republic P-47D-11-RA Thunderbolt 
42-23114/23142  Republic P-47D-16-RA Thunderbolt 
42-23143/23299  Republic P-47D-15-RA Thunderbolt 
42-25274/25322  Republic P-47D-20-RE Thunderbolt 
42-25323/25538  Republic P-47D-21-RE Thunderbolt 
42-25539/26388  Republic P-47D-22-RE Thunderbolt 
42-26389/26773  Republic P-47D-25-RE Thunderbolt 
42-26774/27388  Republic P-47D-27-RE Thunderbolt 
42-27389/28188  Republic P-47D-23-RA Thunderbolt 
42-28189/28438  Republic P-47D-26-RA Thunderbolt 
42-28439/29466  Republic P-47D-27-RA Thunderbolt 
42-74615/74964  Republic P-47D-6-RE Thunderbolt 
42-74965/75214  Republic P-47D-10-RE Thunderbolt 
42-75215/75614  Republic P-47D-11-RE Thunderbolt 
42-75615/75814  Republic P-47D-15-RE Thunderbolt 
42-75865/76118  Republic P-47D-16-RE Thunderbolt 
42-76119/76364  Republic P-47D-15-RE Thunderbolt 
42-76365/76614  Republic P-47D-20-RE Thunderbolt 
43-25254/25440  Republic P-47D-20-RA Thunderbolt 
43-25441/25664  Republic P-47D-21-RA Thunderbolt 
43-25665/25753  Republic P-47D-23-RA Thunderbolt 
44-19558/20307  Republic P-47D-28-RE Thunderbolt 
44-20308/21107  Republic P-47D-30-RE Thunderbolt 
44-32668/33867  Republic P-47D-30-RA Thunderbolt 
44-89684/90283  Republic P-47D-30-RA Thunderbolt 
44-90284/90483  Republic P-47D-40-RA Thunderbolt 
45-49090/49554  Republic P-47D-40-RA Thunderbolt 

Serials of Curtiss-built P-47Gs: 

42-24920/24939 	Curtiss P-47G-CU Thunderbolt 
42-24940/24979  Curtiss P-47G-1-CU Thunderbolt 
42-24980/25039  Curtiss P-47G-5-CU Thunderbolt 
42-25040/25119  Curtiss P-47G-10-CU Thunderbolt 
42-25120/25273  Curtiss P-47G-15-CU Thunderbolt 

Sources:

  American Combat Planes, Ray Wagner, Third Enlarged Edition, Doubleday, 
  1982.  

  The American Fighter, Enzo Angelucci and Peter Bowers, Orion Books, 
  1987.  

  War Planes of the Second World War, Fighters, Volume Four, William 
  Green, Doubleday 1964.  

  United States Military Aircraft since 1909, Gordon Swanborough and 
  Peter M. Bowers, Smithsonian, 1989.  

  The Republic P-47D Thunderbolt, Aircraft in Profile, Edward Shacklady, 
  Doubleday, 1969.  

  Famous Fighters of the Second World War, Volume I, William Green, 
  1967.  

  Thunderbolt!, Robert S.  Johnson and Martin Caidin, Ballantine Books, 
  1958.  

  British Military Aircraft Serials, 1912-1969, Bruce Robertson, Ian 
  Allen, 1969.  

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548