| Delaware Military History |
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P-47 Thunderbolt
P-47 Fighter Pilot Training at Dover AFB
Dover Air Force Base had three missions during World War II. It began as a base for anti-
submarine patrols. Late in the war, it served as a secret testing site for aerial rocketry. But the
primary wartime mission at Dover Air Force Base during World War II was fighter pilot training.
After Pearl Harbor there was a pressing need for complete new units as the Air Force rapidly grew
in strength. After completion of individual training, pilots were given eight to twelve weeks of
training as a team using the same aircraft they would use in combat. This program inspired the
implementation of Operational Training Units (OTUs) in the USAAF.
The first American OTUs began in early 1942, but were immediately plagued with problems. The
demands of the combat units had to be met at the expense of the training programs and shortages
of personnel, aircraft, equipment, and supplies slowed and reduced the effectiveness of the training.
Many of the training fields throughout the county were inadequate or under construction. Dover
Army Air Base was closed to flying operations from February to August 1943 while the existing
runways were lengthened to 7,000 feet, and 29,000 square yards of paved apron was being
constructed. It had really been a “Dog patch” airstrip until then, and the new expansion paved the
way for a more prominent role in the war effort. Dozens of new buildings were constructed by
civilian contractors, many of whom are still in business today, such as McHugh Electric, George&
Lynch, Rupert Construction and Henkels & McCoy to name just a few.
The first OTU at Dover was the 365th Fighter Group including the 386th, 387th and 388th Fighter
Squadrons. Their stay at Dover was brief, only three months as an operational warm up for their
overseas assignment. The 365th was posted to a combat tour in England in December 1943 with
9th Air Force and was de-activated after the War was over in September 1945.
Through the OTU system the USAAF had created all of new combat units required by the end of
1943, but a constant flow of new pilots was needed to replace those captured, killed in action, or
rotated back to United States. Most of the training bases in the United States discontinued OTU
training and switched their training emphasis to Replacement Training Units (RTUs).
In the RTU system, replacement pilots where sent to RTUs or Combat Crew Training Stations
(CCTSs) where they were given 12 weeks of training similar to the OTU program. Less time was
needed for squadron and group integration, since the pilots were not yet part of a combat unit.
Once all training was completed, pilots were drawn from the RTUs to serve in overseas units.
The 120 flying hour / 12 week program of training was split between two locations. The P-47
transition training was given at Blackstone Virginia for the new RTU pilots. The balance of the
training, or advanced training was finished at Dover. Pilots were not immediately placed in
advanced training upon arrival at Dover. They were first given a preflight examination that
included radio range, link trainer, cockpit "feel", landing gear operation, parking, and taxing. After
successful completion of the examination, pilots were started in Advanced Fighter Training.
The 312th Army Air Corps Base Unit (BU) began combat training operations at the Base on the
August 1, 1943, teaching pilots the complexities of the P-47 Thunderbolt fighter, under the
command of Captain Alanson H. Wilson.
For most of the war, Dover was mostly a P-47 fighter training base. Built in greater quantities
than any other US fighter, the P-47 also known as the “Jug”, was the heaviest single-engine
WWII fighter to go into production. The Thunderbolt performed 546,000 combat sorties between
March of 1943 and August 1945 and is considered the real forerunner of today's multi-role fighters.
Seven squadrons in all from the 83rd Fighter Group and the 365th Fighter Groups were involved
in preparing these pilots for European combat. Initially the organization was responsible for
operational training, while it later continued as a replacement training unit.
The 1004th Guard Squadron stood up along with the 312th to be the base security section. They
were followed on June 25 by the 915th (colored) Guard Squadron and on July 12 by the 1354th
(colored) Guard Squadron. Both colored squadrons shipped out in August and November
respectively. These units were the pioneers of air base defense, being the first Air Corps personnel
to be trained and equipped specifically for air base defense. These units were indeed manned by
colored troops, some 5,000 of them Air Corps-wide. They were trained as infantry, but artillery
and armor were also sometimes attached.
The 365th Fighter Group included the 386th, 387th and 388th Fighter Squadrons. Their stay at
Dover was brief, only three months as an operational warm-up for their overseas assignment.
The 365th was posted to a combat tour in England in December 1943 with 9th Air Force and was
de-activated after the War was over in September 1945.
The 83rd Fighter Group included the 448th, 532nd, 533rd, and 534th Fighter Squadrons. It was a
training unit designed to train individual pilots in a stream of replacements for other combat
crews, lost or transferred from the combat zone. It was attached to the Philadelphia Fighter Wing
from November 22, 1943 to April 10, 1944, when it was disbanded and redesignated as the 125th
Base Unit, from April 10, 1944 – September 15, 1944. Another redesignation came on September
15, 1944 when it was re-named the 125th AAF Base Unit, before disbanding altogether on March
31, 1946.
The training emphasis was on the team of pilot, crew chief, and aircraft as the fundamental
weapons system. This was the professional relationship that was the core of the training mission.
The training and testing cadre at Dover AFB included many returning combat veterans. A typical
example was Capt. Liecester Bishop, who had enlisted in the RCAF in 1940, and later the Eagle
Squadron of the AAF with missions over France, the Low Countries and Germany, earning him a
DFC and Air Medal.
A news release on August 19, 1944 summarized the combat experience of the instructors. Fourteen
of the staff accounted for 110 decorations, and 200 months of overseas combat service experience.
They collectively had 21 enemy planes to their credit, two purple hearts, a dozen DFCs, 14 air
medals and 69 other clusters. And their average age was 25.
The result of this training was manifest when a Dover student pilot, Lt. Michael Brezas, later
compiled an outstanding combat record. The 21-year old ace was credited with twelve aerial
victories against enemy aircraft in the Mediterranean Theater.
Delaware Air National Guard P-47's, 1946-1949
On September 6, 1946, the formal federal recognition and activation of Delaware's first Air
National Guard Unit (142nd Fighter Squadron) took place at a ceremony in the Wilmington
Armory. The ceremony was conducted by Brigadier General Paul R. Rinard, the Adjutant General
and Colonel John B. Grier, U.S. Property and Disbursing Officer for Delaware. The unit would
begin with 49 officers and 263 enlisted men authorized. Actual strength on our founding day was
14 officers, One warrant officer, and 36 enlisted men. These original 51 “plank-owners” were
commanded by Lt. Col. Wallace A. Cameron.
Shortly afterward, the squadron received its first of 25 fighter planes, F-47N "Thunderbolts." In
late 1946, two L-5s and two AT-6 aircraft were received to assist in the training of new pilots. 1947
brought the addition of several more airplanes including C-47s and four B-26 target towing
bombers. The F-47s were replaced by F-84 Thunderjets in 1949. See F-47 Images for more
photographs of the Delaware Air Guard aircraft.
The Airplane
Republic Aviation's P-47 Thunderbolt, also known as the "Jug", was the largest, heaviest, and
most expensive fighter aircraft in history to be powered by a single reciprocating engine.[2] It was
one of the main United States Army Air Forces (USAAF) fighters of World War II, and served
with other Allied air forces. The P-47 was very effective in air combat but proved especially adept
at ground attack. It had eight .50-caliber machine guns, four per wing. When fully loaded the P-47
could weigh up to eight tons. A modern-day counterpart in that role, the A-10 Thunderbolt II,
takes its name from the P-47.
Development
The P-47 Thunderbolt was the product of Russian immigrant Alexander P. de Seversky and
Georgian immigrant Alexander Kartveli, who had left their homelands to escape the Bolsheviks.
In 1939, Republic Aviation designed the AP-4 demonstrator powered by a Pratt & Whitney R-1830
radial engine with a belly-mounted turbocharger. While the resulting P-43 Lancer was in limited
production, Republic had been working on an improved P-44 Rocket with a more powerful
engine, as well as on a fighter designated the AP-10. The latter was a lightweight aircraft powered
by the Allison V-1710 liquid-cooled V-12 engine and armed with eight .50 in (12.7 mm) M2
Browning machine guns. The United States Army Air Corps (USAAC) backed the project and
gave it the designation XP-47.
As the war in Europe escalated in spring 1940, Republic and the USAAC concluded that the XP-44
and the XP-47 were inferior to the German fighters. Republic unsuccessfully attempted to improve
the design, proposing the XP-47A. Alexander Kartveli subsequently came up with an all-new and
much larger fighter which was offered to the USAAC in June 1940. The Air Corps ordered a
prototype in September, to be designated the XP-47B. The XP-47A, which had almost nothing in
common with the new design, was abandoned.
The XP-47B was all-metal construction (except for fabric-covered tail control surfaces) with
elliptical wings, with a straight leading edge that was slightly swept back. The cockpit was roomy
and the pilot's seat was comfortable—"like a lounge chair", as one pilot later put it. The pilot was
provided with every convenience, including cabin air conditioning. The canopy doors hinged
upward. Main and auxiliary self-sealing fuel tanks were placed under the cockpit, giving a total
fuel capacity of 305 U.S. gal (1,155 l).
Power came from a Pratt & Whitney R-2800 Double Wasp two-row 18-cylinder radial engine
producing 2,000 hp (1,500 kW) and turning a four-bladed Curtiss Electric constant-speed propeller
146 in (3.7 m) in diameter. The loss of the AP-4 prototype to an engine fire ended Kartveli's
experiments with tight-fitting cowlings, so the engine was placed in a broad cowling that opened
at the front in a "horse collar"-shaped ellipse. The cowling admitted cooling air for the engine, left
and right oil coolers, and the turbosupercharger intercooler system. The engine exhaust gases
were routed into a pair of wastegate-equipped pipes that ran along each side of the cockpit to drive
the turbosupercharger turbine at the bottom of the fuselage about halfway between cockpit and
tail. At full power, the pipes glowed red at their forward ends and the turbine spun at 21,300 rpm.
[3] The complicated turbosupercharger system with its ductwork gave the XP-47B a deep fuselage,
and the wings had to be mounted in a relatively high position. This was problematic since long
landing gear were needed to provide ground clearance for the propeller. To reduce the size and
weight of the long landing gear and so that wing-mounted machine guns could be fitted, each
main gear strut was fitted with a mechanism by which it telescoped out 9 in (23 cm) when
extended.
The XP-47B was a very large aircraft for its time with an empty weight of 9,900 lb (4,490 kg), or 65
percent more than the YP-43. Kartveli is said to have remarked, "It will be a dinosaur, but it will be
a dinosaur with good proportions."The armament consisted of eight .50 in (12.7 mm) machine
guns, four in each wing. The guns were staggered to allow feeding from side-by-side ammunition
boxes, each with a 350-round capacity. Although the British already possessed eight-gun fighters,
the Hurricane and the Spitfire, and even the twelve-gun Typhoon, they used the smaller 0.303 in
(7.7 mm) guns.
The XP-47B first flew on 6 May 1941 with Lowry P. Brabham at the controls. Although there were
minor problems, such as some cockpit smoke that turned out to be due to an oil drip, the aircraft
proved impressive in its first trials. It was eventually lost in an accident on August 8, 1942, but
before that mishap the prototype had achieved a level speed of 412 mph (663 km/h) at 25,800 ft
(7,864 m) altitude, and had demonstrated a climb from sea level to 15,000 ft (4,600 m) altitude in
five minutes.
The XP-47B gave the newly reorganized United States Army Air Forces cause for both optimism
and apprehension. While possessing good performance and firepower, the XP-47B had its share of
teething problems:
Its sheer size and limited ground-propeller clearance made for challenging takeoffs which required
long runways—the pilot had to hold the tail low until considerable speed was attained on the
initial run.
Republic addressed the problems with a sliding canopy that could be jettisoned in an emergency, a
pressurized ignition system, and new all-metal control surfaces (improved engine-accessory access
had to wait until the P-47C introduced a new engine mount). While the engineers worked
frantically to get their "dinosaur" to fly right, the USAAF ordered 171 P-47Bs. An engineering
prototype P-47B was delivered in December 1941, with a production prototype following in March
1942, and the first production model provided in May. Republic continued to improve the design
as P-47Bs were produced, and although all P-47Bs had the sliding canopy and the new General
Electric turbosupercharger regulator for the R-2800-21 engine, features such as all-metal control
surfaces were not standard at first. A modification unique to the P-47B was the radio mast behind
the cockpit that was slanted forward to maintain the originally designed antenna wire length in
spite of the new sliding canopy.
The P-47B led to a few "one off" variants. A single reconnaissance aircraft designated RP-47B was
built. In September 1942, the 171st and last P-47B (41-6065) was also used as a test platform under
the designation XP-47E to evaluate the R-2800-59 engine, a pressurized cockpit with a hinged
canopy and, eventually, a new Hamilton Standard propeller. The plans for production were
cancelled after increased emphasis on low-level operations over Europe.[6][7] Another P-47B was
later fitted with a new laminar flow wing in search of higher performance and redesignated XP-
47F.
P-47C
Production changes gradually addressed the problems with P-47B, and on the balance, with
experience the USAAF decided that the P-47 was worthwhile, quickly following the initial order
for P-47Bs for 602 more examples of a improved model, named P-47C, with the first of this variant
delivered in September 1942. The initial P-47Cs were very similar to the P-47B.
Initial deliveries of the Thunderbolt to the USAAF were to the 56th Fighter Group, which was
also on Long Island. The 56th served as an operational evaluation unit for the new fighter.
Teething problems continued. A Republic test pilot was killed in an early production P-47B when
it went out of control in a dive, and crashes occurred due to failure of the tail assembly. The
introduction of revised rudder and elevator balance systems and other changes corrected these
problems. In spite of the problems, the USAAF was interested enough to order an additional 602
examples of the refined P-47C, with the first of the variant delivered in September 1942.
Essentially similar to the P-47B, the initial P-47C featured strengthened all-metal control surfaces,
an upgraded GE turbosupercharger regulator, and a short vertical radio mast. After the initial
manufacture of a block of 57 P-47Cs, production moved to the P-47C-1, which had a 13 in (33 cm)
fuselage extension forward of the cockpit at the firewall to correct centre of gravity problems, ease
engine maintenance and allow installation of a new engine mount. There were a number of other
changes, such as revised exhausts for the oil coolers, and fixes to brakes, undercarriage and
electrical system as well as a redesigned rudder and elevator balance. The 55 P-47C-1s were
followed by 128 P-47C-2s which introduced a centerline hardpoint with under-fuselage shackles
for either a 500 lb (227 kg) bomb or a 200 U.S. gal (758 l, 167 Imp gal) fuel tank that conformed to
the underside of the fuselage. The main production P-47C sub-variant was the P-47C-5 which
introduced a new whip antenna and the R-2800-59 engine with water-methanol injection with a
war emergency power rating of 2,300 hp (1,716 kW). With the use of pressurized drop tanks, the P-
47C was able to extend its range on missions beginning 30 July 1943.
By the end of 1942, most of the troubles with the P-47 had been worked out and P-47Cs were sent
to England. The 56th FG was sent overseas to join the Eighth Air Force, whose 4th and 78th
Fighter Groups would be equipped with the Thunderbolt as well.
P-47D / P-47G / XP-47K / XP-47L
Republic P-47D Thunderbolt, nicknamed "Jug;" during World War II, the P-47 served in every
active combat theater and with many Allied air forces.
Refinements of the Thunderbolt continued, leading to the P-47D, which was the most popular
version with 12,602 built. The "D" model actually consisted of a series of evolving production
blocks, the last of which were visibly different from the first.
The first P-47Ds were actually the same as P-47Cs. Republic could not produce Thunderbolts fast
enough at its Farmingdale plant on Long Island, so a new plant was built at Evansville, Indiana.
The Evansville plant built a total of 110 P-47Ds, which were completely identical to P-47C-2s.
Farmingdale aircraft were identified by the "-RE" suffix after the block number, while Evansville
aircraft were given the "-RA" suffix.
The P-47D-1 through P-47D-6, the P-47D-10, and the P-47D-11 successively incorporated changes
such as the addition of more engine cooling flaps around the back of the cowl to reduce the engine
overheating problems that had been seen in the field. Engines and engine subsystems saw
refinement, as did the fuel, oil and hydraulic systems. Additional armor protection was also added
for the pilot.
The P-47D-15 was produced in response to requests by combat units for increased range. The
internal fuel capacity was increased to 375 U.S. gal (1,421 l) and the bomb racks under the wings
were made "wet" (equipped with fuel plumbing) to allow a jettisonable drop tank pressurized by
vented exhaust air to be carried under each wing, in addition to the belly tank. Five different
auxiliary tanks were fitted to the Thunderbolt during its career:
The tanks made of plastic-impregnated (laminated) paper could not store fuel for an extended
period of time, but they worked quite well for the time it took to fly a single mission. These tanks
were cheaper, lighter in weight, and were useless to the enemy if recovered after being dropped—
not only did they break apart, but they did not provide the enemy with any reusable materials
that could be scavenged for their own war effort. With the increased fuel capacity, the P-47 was
now able to perform escort missions deep into enemy territory. A drawback to their use was that
fighters could not land with the tanks in place because of the hazard of rupture and explosion.
Fighters recalled from a mission or that did not jettison for some reason were required to drop
paper tanks into a designated "dump" area at their respective fields, resulting in substantial losses
of aviation fuel.
The P-47D-16, D-20, D-22 and D-23 were similar to the P-47D-15 with minor improvements in the
fuel system, engine subsystems, a jettisonable canopy, and a bulletproof windshield. Beginning
with the block 22 aircraft, the original narrow-chorded Curtiss propeller was replaced by
propellers with larger blades, the Evansville plant switching to a new Curtiss propeller with a
diameter of 13 ft (3.96 m) and the Long Island plant using a Hamilton Standard propeller with a
diameter of 13 ft 2 in (4.01 m). With the bigger propellers having barely 6 in (152 mm) of ground
clearance, Thunderbolt pilots had to learn to be careful on takeoffs to keep the tail down until they
obtained adequate ground clearance, and on landings to flare the aircraft properly. Failure to do so
damaged both the propeller and the runway. A modification to the maingear legs was installed to
extend the gear legs via an electric motor (un-extending before retract) to accommodate the larger
propeller diameter.
Even with two Republic plants rolling out the P-47, the USAAF still was not getting as many
Thunderbolts as they wanted, consequently, an arrangement was made with Curtiss to build the
aircraft under license in a plant in Buffalo, New York. Most of the Curtiss Thunderbolts were
intended for use in advanced flight training. The Curtiss aircraft were all designated P-47G, and a
"-CU" suffix was used to distinguish them from other production. The first P-47G was completely
identical to the P-47C, the P-47G-1 was identical to the P-47C-1, while the following P-47G-5, P-
47G-10, and P-47G-15 sub-variants were comparable to the P-47D-1, P-47D-5 and P-47D-10
respectively. Two P-47G-15s were built with the cockpit extended forward to just before the
leading edge of the wing to provide tandem seating, designated TP-47G. The second crew position
was accommodated by substituting a much smaller main fuel tank. The "Doublebolt" did not go
into production but similar modifications were made in the field to older P-47s, which were then
used as squadron "hacks" (miscellaneous utility aircraft). Curtiss built a total of 354 P-47Gs.
Bubbletop P-47s
All the P-47s to this point had a "razorback" canopy configuration with a tall fuselage spine
behind the pilot which resulted in poor visibility to the rear. The British also had this problem
with their fighter aircraft, and had devised the bulged "Malcolm hood" canopy for the Spitfire as
an initial solution. This was fitted in the field to many North American P-51 Mustangs, and to a
handful of P-47Ds (and far more on P-47Bs and P-47Cs). However, the British then came up with
a much better solution, devising an all-round vision "bubble" canopy for the Hawker Typhoon.
USAAF officials liked the bubble canopy, and quickly adapted it to American fighters, including
the P-51 and the Thunderbolt. The first P-47 with a bubble canopy was a modified P-47D-5
completed in the summer of 1943 and redesignated XP-47K. Another older P-47D was modified to
provide an internal fuel capacity of 370 U.S. gal (1,402 l) and given the designation XP-47L. The
bubble canopy and increased fuel capacity were then rolled into production together, resulting in
the block 25 P-47D (rather than a new variant designation). First deliveries to combat groups
began in May 1944.
It was followed by similar bubble-top variants, including the P-47D-26, D-27, D-28 and D-30.
Improvements added in this series included engine refinements, more internal fuel capacity, and
the addition of dive recovery flaps. Cutting down the rear fuselage to accommodate the bubble
canopy produced yaw instability, and the P-47D-40 introduced a dorsal fin extension in the form
of a narrow triangle running from the vertical tailplane to the radio aerial. The fin fillet was
retrofitted in the field to earlier P-47D bubble-top variants. The P-47D-40 also featured provisions
for ten "zero length" stub launchers for 5 in (127 mm) High velocity aircraft rockets (HVARs), as
well as the new K-14 computing gunsight. This was a license-built copy of the British Ferranti
GGS Mark IID computing gyroscopic sight which allowed the pilot to dial in target wingspan and
range, and would then move the gunsight reticle to compensate for the required deflection.
The bubbletop P-47s were nicknamed "Superbolts" by combat pilots in the field.[9]
XP-47H
XP-47H / XP-47J Republic made several attempts to further improve the P-47D:
Two XP-47Hs were built. They were major reworkings of existing razorback P-47Ds to
accommodate a Chrysler IV-2220-11 water-cooled 16-cylinder inverted vee engine. However, such
large inline engines did not prove to be especially effective.
XP-47J
The XP-47J began as a November 1942 request to Republic for a high-performance version of the
Thunderbolt using a lighter airframe and an uprated engine with water injection and fan cooling.
Kartveli designed an aircraft fitted with a tight-cowled Pratt & Whitney R-2800-57(C) with a war
emergency rating of 2,800 hp (2,090 kW), reduced armament of six 0.50 in (12.7 mm) machine
guns, a new and lighter wing, and many other changes. The only XP-47J was first flown in late
November 1943. When fitted with a GE CH-5 turbosupercharger, the XP-47J achieved a top speed
of 505 mph (440 kn, 813 km/h) in level flight in August 1944, making it one of the fastest piston
engine fighters ever built. However, by that time Republic had moved on to a new concept, the XP-
72.
P-47M
The P-47M was a more conservative attempt to come up with a higher-performance ("Sprint")
version of the Thunderbolt, seeking parity with the newly introduced German jet aircraft and V-1
flying bombs. Four P-47D-27-RE airframes (s/n 42-27385 / 42-27388) were modified into prototype
YP-47Ms by fitting the R-2800-57(C) engine and the GE CH-5 turbo-supercharger, a combination
which could produce 2,800 hp (2,089 kW) at 32,500 ft (9,900 m) when using Wartime Emergency
Power (water injection). Air brakes were added to the wing's lower surfaces to allow braking after
a dive onto its prey. The YP-47M had a top speed of 473 mph (410 kn, 761 km/h) and it was put
into limited production with 130 (sufficient for one group) built. However, the type suffered
serious teething problems in the field due to the highly tuned engine. Engines were unable to
reach operating temperatures and power settings and frequently failed in early flights from a
variety of causes: ignition harnesses cracked at high altitudes, severing electrical connections
between the magneto and distributor, and carburetor valve diaphragms also failed. Persistent oil
tank ruptures in replacement engines were found to be the result of inadequate protection against
salt water corrosion during transshipment. By the time the bugs were worked out, the war in
Europe was nearly over. The entire total of 130 P-47Ms were delivered to the 56th Fighter Group,
and were responsible for all four of that group's jet shoot-downs. Twelve were lost in operational
crashes with the 56th Group resulting in 11 deaths, two after VE Day, and two (44-21134 on 13
April 1945 and 44-21230 on 16 April 1945) were shot down in combat, both by ground fire.
The second YP-47M (of the batch of four converted P-47Ds) was later fitted with new wings and
served as the prototype for the P-47N.
P-47N
The P-47N was the last Thunderbolt variant to be produced. It was designed as an escort fighter
for the B-29 Superfortress bombers flying raids on the Japanese home islands. Increased internal
fuel capacity and drop tanks had done much to extend the Thunderbolt's range during its
evolution, and the only other way to expand the fuel capacity was to put fuel tanks into the
wings. Thus, a new wing was designed with two 50 U.S. gal (190 l) fuel tanks. The second YP-
47N with this wing flew in September 1944. The redesign proved successful in extending range to
about 2,000 mi (3,200 km), and the squared-off wingtips improved the roll rate. The P-47N entered
mass production with the uprated R-2800-77(C) engine, with a total of 1,816 built.
The very last Thunderbolt to be built, a P-47N-25, rolled off the production line in October 1945.
Thousands more had been on order, but production was halted with the end of the war in
August. At the end of production, a Thunderbolt cost $83,000 in 1945 U.S. dollars. A total of
15,686 Thunderbolts of all types were built, making it second most produced American fighter of
all times—after the 16,766 P-51 Mustangs. A number of P-47s have survived to the present day,
and a few are still flying.
Operational history
US service
By the end of 1942 P-47Cs were sent to England for combat operations. The initial Thunderbolt
flyers, 56th Fighter Group, was sent overseas to join the 8th Air Force. Two Fighter Groups
already stationing in England began introducing the Jugs in January 1943: the Spitfire-flying 4th
Fighter Group, a unit built around a core of experienced American volunteers of the Eagle
Squadrons; and the 78th Fighter Group, formerly using P-38 Lightning.
Beginning in January 1943, Thunderbolt fighters were sent to the joint Army Air Forces – civilian
Millville Airport in Millville, New Jersey in order to train civilian and military pilots. they were
joined in August by an additional unit, the 312th Army Air Corps Base Unit at Dover Army Air
Force Base, Dover Delaware.
The first P-47 combat mission took place 10 March 1943 when the 4th FG took their aircraft on a
fighter sweep over France. The mission was a failure due to radio malfunctions. All P-47s were
refitted with British radios, and missions resumed 8 April. The first P-47 air combat took place 15
April with Major Don Blakeslee of the 4th FG scoring the Thunderbolt's first air victory (an FW-
190). On 17 August, P-47s performed their first large-scale escort missions, providing B-17
bombers with both penetration and withdrawal support of the Schweinfurt-Regensburg mission,
and claiming 19 kills against three losses.
By mid-1943, the Jug was also in service with the 12th Air Force in Italy, and it was fighting
against the Japanese in the Pacific with the 348th Fighter Group flying escort missions out of
Brisbane, Australia. By 1944, the Thunderbolt was in combat with the USAAF in all its
operational theaters, except Alaska.
Although the P-51 Mustang replaced the P-47 in the long-range escort role in Europe, the
Thunderbolt still ended the war with 3,752 air-to-air kills claimed in over 746,000 sorties of all
types, at the cost of 3,499 P-47s to all causes in combat.[11] In Europe in the critical first three
months of 1944, when the German aircraft industry and Berlin were heavily attacked, the P-47
shot down more German fighters than did the P-51 (570 out of 873), and shot down
approximately 900 of the 1,983 claimed during the first six months of 1944. In Europe,
Thunderbolts flew more sorties (423,435) than P-51s, P-38s and P-40s combined.
By the end of the war, the 56th FG was the only 8th Air Force unit still flying the P-47, by
preference, instead of the P-51. The unit claimed 677.5 air victories and 311 ground kills, at the cost
of 128 aircraft.[13] Lieutenant Colonel Francis S. Gabreski scored 31 victories,[14] including three
ground kills, Captain Bob Johnson scored 27 (with one unconfirmed probable kill leading to some
giving his tally as 28),[15] and 56th FG Commanding Officer Colonel Hubert Zemke scored 17.75
kills.[16] Despite being the sole remaining P-47 group in the 8th Air Force, the 56th FG remained
its top-scoring group in aerial victories throughout the war.
With increases in fuel capacity as the type was refined, the range of escort missions over Europe
steadily increased until the P-47 was able to accompany bombers in raids all the way into
Germany. On the way back from the raids, pilots shot up ground targets of opportunity, and also
used belly shackles to carry bombs on short-range missions, which led to the realization that the
P-47 could perform a dual-function on escort missions as a fighter-bomber. Even with its
complicated turbosupercharger system, its sturdy airframe and tough radial engine could absorb a
lot of damage and still return home. Some pilots readily chose to belly-land their burning
Thunderbolts rather than risk bailing out; there are instances of P-47s crash-landing after being
shot down, hitting trees and causing impacts severe enough to snap off wings, tail, and engine,
while the pilot escaped with few or no injuries.
The P-47 gradually became the USAAF's best fighter-bomber, normally carrying 500 lb (227 kg)
bombs, M8 4.5 in (115 mm) or 5 in (127 mm) High velocity aircraft rockets (HVARs, or Holy
Moses). From the invasion of Europe on 6 June 1944 to VE day on 7 May 1945, the Thunderbolt
units claimed destroyed: 86,000 railroad cars, 9,000 locomotives, 6,000 armoured fighting vehicles,
and 68,000 trucks.
Postwar service
The USAAF Strategic Air Command had P-47 Thunderbolts in service from 1946 through 1947.
The P-47 served with the Army Air Forces (United States Air Force after 1947) until 1949, and with
the Air National Guard until 1953, receiving the designation F-47 in 1948. P-47s also served as
spotters for rescue aircraft such as the OA-10 Catalina and Boeing B-17H.
The F-51 Mustang was used by the USAF during the Korean War, mainly in the close air support
role with the F-47 not being deployed to Korea. Since the Mustang was more vulnerable to being
shot down, (and many were lost due to anti-aircraft fire), some former F-47 pilots suggested the
more durable Thunderbolt should have been sent to Korea; however the F-51D was available in
greater numbers in the USAF and ANG inventories.
P-47 Fighter Pilot Training at Dover AFB
Dover Air Force Base had three missions during World War II. It began as a base for anti-
submarine patrols. Late in the war, it served as a secret testing site for aerial rocketry. But the
primary wartime mission at Dover Air Force Base during World War II was fighter pilot training.
After Pearl Harbor there was a pressing need for complete new units as the Air Force rapidly grew
in strength. After completion of individual training, pilots were given eight to twelve weeks of
training as a team using the same aircraft they would use in combat. This program inspired the
implementation of Operational Training Units (OTUs) in the USAAF.
The first American OTUs began in early 1942, but were immediately plagued with problems. The
demands of the combat units had to be met at the expense of the training programs and shortages
of personnel, aircraft, equipment, and supplies slowed and reduced the effectiveness of the training.
Many of the training fields throughout the county were inadequate or under construction. Dover
Army Air Base was closed to flying operations from February to August 1943 while the existing
runways were lengthened to 7,000 feet, and 29,000 square yards of paved apron was being
constructed. It had really been a “Dog patch” airstrip until then, and the new expansion paved the
way for a more prominent role in the war effort. Dozens of new buildings were constructed by
civilian contractors, many of whom are still in business today, such as McHugh Electric, George&
Lynch, Rupert Construction and Henkels & McCoy to name just a few.
The first OTU at Dover was the 365th Fighter Group including the 386th, 387th and 388th Fighter
Squadrons. Their stay at Dover was brief, only three months as an operational warm up for their
overseas assignment. The 365th was posted to a combat tour in England in December 1943 with
9th Air Force and was de-activated after the War was over in September 1945.
Through the OTU system the USAAF had created all of new combat units required by the end of
1943, but a constant flow of new pilots was needed to replace those captured, killed in action, or
rotated back to United States. Most of the training bases in the United States discontinued OTU
training and switched their training emphasis to Replacement Training Units (RTUs).
In the RTU system, replacement pilots where sent to RTUs or Combat Crew Training Stations
(CCTSs) where they were given 12 weeks of training similar to the OTU program. Less time was
needed for squadron and group integration, since the pilots were not yet part of a combat unit.
Once all training was completed, pilots were drawn from the RTUs to serve in overseas units.
The 120 flying hour / 12 week program of training was split between two locations. The P-47
transition training was given at Blackstone Virginia for the new RTU pilots. The balance of the
training, or advanced training was finished at Dover. Pilots were not immediately placed in
advanced training upon arrival at Dover. They were first given a preflight examination that
included radio range, link trainer, cockpit "feel", landing gear operation, parking, and taxing. After
successful completion of the examination, pilots were started in Advanced Fighter Training.
The 312th Army Air Corps Base Unit (BU) began combat training operations at the Base on the
August 1, 1943, teaching pilots the complexities of the P-47 Thunderbolt fighter, under the
command of Captain Alanson H. Wilson.
For most of the war, Dover was mostly a P-47 fighter training base. Built in greater quantities
than any other US fighter, the P-47 also known as the “Jug”, was the heaviest single-engine
WWII fighter to go into production. The Thunderbolt performed 546,000 combat sorties between
March of 1943 and August 1945 and is considered the real forerunner of today's multi-role fighters.
Seven squadrons in all from the 83rd Fighter Group and the 365th Fighter Groups were involved
in preparing these pilots for European combat. Initially the organization was responsible for
operational training, while it later continued as a replacement training unit.
The 1004th Guard Squadron stood up along with the 312th to be the base security section. They
were followed on June 25 by the 915th (colored) Guard Squadron and on July 12 by the 1354th
(colored) Guard Squadron. Both colored squadrons shipped out in August and November
respectively. These units were the pioneers of air base defense, being the first Air Corps personnel
to be trained and equipped specifically for air base defense. These units were indeed manned by
colored troops, some 5,000 of them Air Corps-wide. They were trained as infantry, but artillery
and armor were also sometimes attached.
The 365th Fighter Group included the 386th, 387th and 388th Fighter Squadrons. Their stay at
Dover was brief, only three months as an operational warm-up for their overseas assignment.
The 365th was posted to a combat tour in England in December 1943 with 9th Air Force and was
de-activated after the War was over in September 1945.
The 83rd Fighter Group included the 448th, 532nd, 533rd, and 534th Fighter Squadrons. It was a
training unit designed to train individual pilots in a stream of replacements for other combat
crews, lost or transferred from the combat zone. It was attached to the Philadelphia Fighter Wing
from November 22, 1943 to April 10, 1944, when it was disbanded and redesignated as the 125th
Base Unit, from April 10, 1944 – September 15, 1944. Another redesignation came on September
15, 1944 when it was re-named the 125th AAF Base Unit, before disbanding altogether on March
31, 1946.
The training emphasis was on the team of pilot, crew chief, and aircraft as the fundamental
weapons system. This was the professional relationship that was the core of the training mission.
The training and testing cadre at Dover AFB included many returning combat veterans. A typical
example was Capt. Liecester Bishop, who had enlisted in the RCAF in 1940, and later the Eagle
Squadron of the AAF with missions over France, the Low Countries and Germany, earning him a
DFC and Air Medal.
A news release on August 19, 1944 summarized the combat experience of the instructors. Fourteen
of the staff accounted for 110 decorations, and 200 months of overseas combat service experience.
They collectively had 21 enemy planes to their credit, two purple hearts, a dozen DFCs, 14 air
medals and 69 other clusters. And their average age was 25.
The result of this training was manifest when a Dover student pilot, Lt. Michael Brezas, later
compiled an outstanding combat record. The 21-year old ace was credited with twelve aerial
victories against enemy aircraft in the Mediterranean Theater.
Delaware Air National Guard P-47's, 1946-1949
On September 6, 1946, the formal federal recognition and activation of Delaware's first Air
National Guard Unit (142nd Fighter Squadron) took place at a ceremony in the Wilmington
Armory. The ceremony was conducted by Brigadier General Paul R. Rinard, the Adjutant General
and Colonel John B. Grier, U.S. Property and Disbursing Officer for Delaware. The unit would
begin with 49 officers and 263 enlisted men authorized. Actual strength on our founding day was
14 officers, One warrant officer, and 36 enlisted men. These original 51 “plank-owners” were
commanded by Lt. Col. Wallace A. Cameron.
Shortly afterward, the squadron received its first of 25 fighter planes, F-47N "Thunderbolts." In
late 1946, two L-5s and two AT-6 aircraft were received to assist in the training of new pilots. 1947
brought the addition of several more airplanes including C-47s and four B-26 target towing
bombers. The F-47s were replaced by F-84 Thunderjets in 1949. See F-47 Images for more
photographs of the Delaware Air Guard aircraft.
The Airplane
Republic Aviation's P-47 Thunderbolt, also known as the "Jug", was the largest, heaviest, and
most expensive fighter aircraft in history to be powered by a single reciprocating engine.[2] It was
one of the main United States Army Air Forces (USAAF) fighters of World War II, and served
with other Allied air forces. The P-47 was very effective in air combat but proved especially adept
at ground attack. It had eight .50-caliber machine guns, four per wing. When fully loaded the P-47
could weigh up to eight tons. A modern-day counterpart in that role, the A-10 Thunderbolt II,
takes its name from the P-47.
Development
The P-47 Thunderbolt was the product of Russian immigrant Alexander P. de Seversky and
Georgian immigrant Alexander Kartveli, who had left their homelands to escape the Bolsheviks.
In 1939, Republic Aviation designed the AP-4 demonstrator powered by a Pratt & Whitney R-1830
radial engine with a belly-mounted turbocharger. While the resulting P-43 Lancer was in limited
production, Republic had been working on an improved P-44 Rocket with a more powerful
engine, as well as on a fighter designated the AP-10. The latter was a lightweight aircraft powered
by the Allison V-1710 liquid-cooled V-12 engine and armed with eight .50 in (12.7 mm) M2
Browning machine guns. The United States Army Air Corps (USAAC) backed the project and
gave it the designation XP-47.
As the war in Europe escalated in spring 1940, Republic and the USAAC concluded that the XP-44
and the XP-47 were inferior to the German fighters. Republic unsuccessfully attempted to improve
the design, proposing the XP-47A. Alexander Kartveli subsequently came up with an all-new and
much larger fighter which was offered to the USAAC in June 1940. The Air Corps ordered a
prototype in September, to be designated the XP-47B. The XP-47A, which had almost nothing in
common with the new design, was abandoned.
The XP-47B was all-metal construction (except for fabric-covered tail control surfaces) with
elliptical wings, with a straight leading edge that was slightly swept back. The cockpit was roomy
and the pilot's seat was comfortable—"like a lounge chair", as one pilot later put it. The pilot was
provided with every convenience, including cabin air conditioning. The canopy doors hinged
upward. Main and auxiliary self-sealing fuel tanks were placed under the cockpit, giving a total
fuel capacity of 305 U.S. gal (1,155 l).
Power came from a Pratt & Whitney R-2800 Double Wasp two-row 18-cylinder radial engine
producing 2,000 hp (1,500 kW) and turning a four-bladed Curtiss Electric constant-speed propeller
146 in (3.7 m) in diameter. The loss of the AP-4 prototype to an engine fire ended Kartveli's
experiments with tight-fitting cowlings, so the engine was placed in a broad cowling that opened
at the front in a "horse collar"-shaped ellipse. The cowling admitted cooling air for the engine, left
and right oil coolers, and the turbosupercharger intercooler system. The engine exhaust gases
were routed into a pair of wastegate-equipped pipes that ran along each side of the cockpit to drive
the turbosupercharger turbine at the bottom of the fuselage about halfway between cockpit and
tail. At full power, the pipes glowed red at their forward ends and the turbine spun at 21,300 rpm.
[3] The complicated turbosupercharger system with its ductwork gave the XP-47B a deep fuselage,
and the wings had to be mounted in a relatively high position. This was problematic since long
landing gear were needed to provide ground clearance for the propeller. To reduce the size and
weight of the long landing gear and so that wing-mounted machine guns could be fitted, each
main gear strut was fitted with a mechanism by which it telescoped out 9 in (23 cm) when
extended.
The XP-47B was a very large aircraft for its time with an empty weight of 9,900 lb (4,490 kg), or 65
percent more than the YP-43. Kartveli is said to have remarked, "It will be a dinosaur, but it will be
a dinosaur with good proportions."The armament consisted of eight .50 in (12.7 mm) machine
guns, four in each wing. The guns were staggered to allow feeding from side-by-side ammunition
boxes, each with a 350-round capacity. Although the British already possessed eight-gun fighters,
the Hurricane and the Spitfire, and even the twelve-gun Typhoon, they used the smaller 0.303 in
(7.7 mm) guns.
The XP-47B first flew on 6 May 1941 with Lowry P. Brabham at the controls. Although there were
minor problems, such as some cockpit smoke that turned out to be due to an oil drip, the aircraft
proved impressive in its first trials. It was eventually lost in an accident on August 8, 1942, but
before that mishap the prototype had achieved a level speed of 412 mph (663 km/h) at 25,800 ft
(7,864 m) altitude, and had demonstrated a climb from sea level to 15,000 ft (4,600 m) altitude in
five minutes.
The XP-47B gave the newly reorganized United States Army Air Forces cause for both optimism
and apprehension. While possessing good performance and firepower, the XP-47B had its share of
teething problems:
Its sheer size and limited ground-propeller clearance made for challenging takeoffs which required
long runways—the pilot had to hold the tail low until considerable speed was attained on the
initial run.
- The sideways-opening canopy covers had a tendency to jam.
- The multiple-gun installation, with its tight fit and cramped ammunition belt tracks,
experienced jamming problems, especially during and after hard maneuvering. - Maneuverability was less than desired when compared to the Supermarine Spitfire and Bf-
109. - The ignition system arced at high altitude.
- Access to the rear engine accessory pad was difficult due to the short engine mount used.
- At high altitude the ailerons "snatched and froze".
- At high speeds the control loads were deemed excessive.
Republic addressed the problems with a sliding canopy that could be jettisoned in an emergency, a
pressurized ignition system, and new all-metal control surfaces (improved engine-accessory access
had to wait until the P-47C introduced a new engine mount). While the engineers worked
frantically to get their "dinosaur" to fly right, the USAAF ordered 171 P-47Bs. An engineering
prototype P-47B was delivered in December 1941, with a production prototype following in March
1942, and the first production model provided in May. Republic continued to improve the design
as P-47Bs were produced, and although all P-47Bs had the sliding canopy and the new General
Electric turbosupercharger regulator for the R-2800-21 engine, features such as all-metal control
surfaces were not standard at first. A modification unique to the P-47B was the radio mast behind
the cockpit that was slanted forward to maintain the originally designed antenna wire length in
spite of the new sliding canopy.
The P-47B led to a few "one off" variants. A single reconnaissance aircraft designated RP-47B was
built. In September 1942, the 171st and last P-47B (41-6065) was also used as a test platform under
the designation XP-47E to evaluate the R-2800-59 engine, a pressurized cockpit with a hinged
canopy and, eventually, a new Hamilton Standard propeller. The plans for production were
cancelled after increased emphasis on low-level operations over Europe.[6][7] Another P-47B was
later fitted with a new laminar flow wing in search of higher performance and redesignated XP-
47F.
P-47C
Production changes gradually addressed the problems with P-47B, and on the balance, with
experience the USAAF decided that the P-47 was worthwhile, quickly following the initial order
for P-47Bs for 602 more examples of a improved model, named P-47C, with the first of this variant
delivered in September 1942. The initial P-47Cs were very similar to the P-47B.
Initial deliveries of the Thunderbolt to the USAAF were to the 56th Fighter Group, which was
also on Long Island. The 56th served as an operational evaluation unit for the new fighter.
Teething problems continued. A Republic test pilot was killed in an early production P-47B when
it went out of control in a dive, and crashes occurred due to failure of the tail assembly. The
introduction of revised rudder and elevator balance systems and other changes corrected these
problems. In spite of the problems, the USAAF was interested enough to order an additional 602
examples of the refined P-47C, with the first of the variant delivered in September 1942.
Essentially similar to the P-47B, the initial P-47C featured strengthened all-metal control surfaces,
an upgraded GE turbosupercharger regulator, and a short vertical radio mast. After the initial
manufacture of a block of 57 P-47Cs, production moved to the P-47C-1, which had a 13 in (33 cm)
fuselage extension forward of the cockpit at the firewall to correct centre of gravity problems, ease
engine maintenance and allow installation of a new engine mount. There were a number of other
changes, such as revised exhausts for the oil coolers, and fixes to brakes, undercarriage and
electrical system as well as a redesigned rudder and elevator balance. The 55 P-47C-1s were
followed by 128 P-47C-2s which introduced a centerline hardpoint with under-fuselage shackles
for either a 500 lb (227 kg) bomb or a 200 U.S. gal (758 l, 167 Imp gal) fuel tank that conformed to
the underside of the fuselage. The main production P-47C sub-variant was the P-47C-5 which
introduced a new whip antenna and the R-2800-59 engine with water-methanol injection with a
war emergency power rating of 2,300 hp (1,716 kW). With the use of pressurized drop tanks, the P-
47C was able to extend its range on missions beginning 30 July 1943.
By the end of 1942, most of the troubles with the P-47 had been worked out and P-47Cs were sent
to England. The 56th FG was sent overseas to join the Eighth Air Force, whose 4th and 78th
Fighter Groups would be equipped with the Thunderbolt as well.
P-47D / P-47G / XP-47K / XP-47L
Republic P-47D Thunderbolt, nicknamed "Jug;" during World War II, the P-47 served in every
active combat theater and with many Allied air forces.
Refinements of the Thunderbolt continued, leading to the P-47D, which was the most popular
version with 12,602 built. The "D" model actually consisted of a series of evolving production
blocks, the last of which were visibly different from the first.
The first P-47Ds were actually the same as P-47Cs. Republic could not produce Thunderbolts fast
enough at its Farmingdale plant on Long Island, so a new plant was built at Evansville, Indiana.
The Evansville plant built a total of 110 P-47Ds, which were completely identical to P-47C-2s.
Farmingdale aircraft were identified by the "-RE" suffix after the block number, while Evansville
aircraft were given the "-RA" suffix.
The P-47D-1 through P-47D-6, the P-47D-10, and the P-47D-11 successively incorporated changes
such as the addition of more engine cooling flaps around the back of the cowl to reduce the engine
overheating problems that had been seen in the field. Engines and engine subsystems saw
refinement, as did the fuel, oil and hydraulic systems. Additional armor protection was also added
for the pilot.
The P-47D-15 was produced in response to requests by combat units for increased range. The
internal fuel capacity was increased to 375 U.S. gal (1,421 l) and the bomb racks under the wings
were made "wet" (equipped with fuel plumbing) to allow a jettisonable drop tank pressurized by
vented exhaust air to be carried under each wing, in addition to the belly tank. Five different
auxiliary tanks were fitted to the Thunderbolt during its career:
- 200 U.S. gallon (758 l) ferry tank, a conformal tub-shaped jettisonable tank made of paper,
which barely cleared the ground on grass airfields, was used as an interim measure between
30 July and 31 August 1943; - 75 U.S. gal (284 l) drop tank, a teardrop-shaped steel tank produced for the P-39 Airacobra,
was adapted to the P-47 beginning 31 August 1943, initially carried on a belly shackle but
used in pairs in 1944 as underwing tanks; - 108 U.S. gal (409 l) drop tank, a cylindrical paper tank of British design and manufacture,
used as a belly tank beginning in September 1943 and a wing tank in April 1944; - 150 U.S. gal (568 l) drop tank, a steel tank first used as a belly 20 February 1944, and an
underwing tank 22 May 1944; - 215 U.S. gal (810 l) belly tank, a wide, flat steel tank developed by VIII Service Command
that allowed performance-degrading wing pylons to be removed, was first used in February
1945.
The tanks made of plastic-impregnated (laminated) paper could not store fuel for an extended
period of time, but they worked quite well for the time it took to fly a single mission. These tanks
were cheaper, lighter in weight, and were useless to the enemy if recovered after being dropped—
not only did they break apart, but they did not provide the enemy with any reusable materials
that could be scavenged for their own war effort. With the increased fuel capacity, the P-47 was
now able to perform escort missions deep into enemy territory. A drawback to their use was that
fighters could not land with the tanks in place because of the hazard of rupture and explosion.
Fighters recalled from a mission or that did not jettison for some reason were required to drop
paper tanks into a designated "dump" area at their respective fields, resulting in substantial losses
of aviation fuel.
The P-47D-16, D-20, D-22 and D-23 were similar to the P-47D-15 with minor improvements in the
fuel system, engine subsystems, a jettisonable canopy, and a bulletproof windshield. Beginning
with the block 22 aircraft, the original narrow-chorded Curtiss propeller was replaced by
propellers with larger blades, the Evansville plant switching to a new Curtiss propeller with a
diameter of 13 ft (3.96 m) and the Long Island plant using a Hamilton Standard propeller with a
diameter of 13 ft 2 in (4.01 m). With the bigger propellers having barely 6 in (152 mm) of ground
clearance, Thunderbolt pilots had to learn to be careful on takeoffs to keep the tail down until they
obtained adequate ground clearance, and on landings to flare the aircraft properly. Failure to do so
damaged both the propeller and the runway. A modification to the maingear legs was installed to
extend the gear legs via an electric motor (un-extending before retract) to accommodate the larger
propeller diameter.
Even with two Republic plants rolling out the P-47, the USAAF still was not getting as many
Thunderbolts as they wanted, consequently, an arrangement was made with Curtiss to build the
aircraft under license in a plant in Buffalo, New York. Most of the Curtiss Thunderbolts were
intended for use in advanced flight training. The Curtiss aircraft were all designated P-47G, and a
"-CU" suffix was used to distinguish them from other production. The first P-47G was completely
identical to the P-47C, the P-47G-1 was identical to the P-47C-1, while the following P-47G-5, P-
47G-10, and P-47G-15 sub-variants were comparable to the P-47D-1, P-47D-5 and P-47D-10
respectively. Two P-47G-15s were built with the cockpit extended forward to just before the
leading edge of the wing to provide tandem seating, designated TP-47G. The second crew position
was accommodated by substituting a much smaller main fuel tank. The "Doublebolt" did not go
into production but similar modifications were made in the field to older P-47s, which were then
used as squadron "hacks" (miscellaneous utility aircraft). Curtiss built a total of 354 P-47Gs.
Bubbletop P-47s
All the P-47s to this point had a "razorback" canopy configuration with a tall fuselage spine
behind the pilot which resulted in poor visibility to the rear. The British also had this problem
with their fighter aircraft, and had devised the bulged "Malcolm hood" canopy for the Spitfire as
an initial solution. This was fitted in the field to many North American P-51 Mustangs, and to a
handful of P-47Ds (and far more on P-47Bs and P-47Cs). However, the British then came up with
a much better solution, devising an all-round vision "bubble" canopy for the Hawker Typhoon.
USAAF officials liked the bubble canopy, and quickly adapted it to American fighters, including
the P-51 and the Thunderbolt. The first P-47 with a bubble canopy was a modified P-47D-5
completed in the summer of 1943 and redesignated XP-47K. Another older P-47D was modified to
provide an internal fuel capacity of 370 U.S. gal (1,402 l) and given the designation XP-47L. The
bubble canopy and increased fuel capacity were then rolled into production together, resulting in
the block 25 P-47D (rather than a new variant designation). First deliveries to combat groups
began in May 1944.
It was followed by similar bubble-top variants, including the P-47D-26, D-27, D-28 and D-30.
Improvements added in this series included engine refinements, more internal fuel capacity, and
the addition of dive recovery flaps. Cutting down the rear fuselage to accommodate the bubble
canopy produced yaw instability, and the P-47D-40 introduced a dorsal fin extension in the form
of a narrow triangle running from the vertical tailplane to the radio aerial. The fin fillet was
retrofitted in the field to earlier P-47D bubble-top variants. The P-47D-40 also featured provisions
for ten "zero length" stub launchers for 5 in (127 mm) High velocity aircraft rockets (HVARs), as
well as the new K-14 computing gunsight. This was a license-built copy of the British Ferranti
GGS Mark IID computing gyroscopic sight which allowed the pilot to dial in target wingspan and
range, and would then move the gunsight reticle to compensate for the required deflection.
The bubbletop P-47s were nicknamed "Superbolts" by combat pilots in the field.[9]
XP-47H
XP-47H / XP-47J Republic made several attempts to further improve the P-47D:
Two XP-47Hs were built. They were major reworkings of existing razorback P-47Ds to
accommodate a Chrysler IV-2220-11 water-cooled 16-cylinder inverted vee engine. However, such
large inline engines did not prove to be especially effective.
XP-47J
The XP-47J began as a November 1942 request to Republic for a high-performance version of the
Thunderbolt using a lighter airframe and an uprated engine with water injection and fan cooling.
Kartveli designed an aircraft fitted with a tight-cowled Pratt & Whitney R-2800-57(C) with a war
emergency rating of 2,800 hp (2,090 kW), reduced armament of six 0.50 in (12.7 mm) machine
guns, a new and lighter wing, and many other changes. The only XP-47J was first flown in late
November 1943. When fitted with a GE CH-5 turbosupercharger, the XP-47J achieved a top speed
of 505 mph (440 kn, 813 km/h) in level flight in August 1944, making it one of the fastest piston
engine fighters ever built. However, by that time Republic had moved on to a new concept, the XP-
72.
P-47M
The P-47M was a more conservative attempt to come up with a higher-performance ("Sprint")
version of the Thunderbolt, seeking parity with the newly introduced German jet aircraft and V-1
flying bombs. Four P-47D-27-RE airframes (s/n 42-27385 / 42-27388) were modified into prototype
YP-47Ms by fitting the R-2800-57(C) engine and the GE CH-5 turbo-supercharger, a combination
which could produce 2,800 hp (2,089 kW) at 32,500 ft (9,900 m) when using Wartime Emergency
Power (water injection). Air brakes were added to the wing's lower surfaces to allow braking after
a dive onto its prey. The YP-47M had a top speed of 473 mph (410 kn, 761 km/h) and it was put
into limited production with 130 (sufficient for one group) built. However, the type suffered
serious teething problems in the field due to the highly tuned engine. Engines were unable to
reach operating temperatures and power settings and frequently failed in early flights from a
variety of causes: ignition harnesses cracked at high altitudes, severing electrical connections
between the magneto and distributor, and carburetor valve diaphragms also failed. Persistent oil
tank ruptures in replacement engines were found to be the result of inadequate protection against
salt water corrosion during transshipment. By the time the bugs were worked out, the war in
Europe was nearly over. The entire total of 130 P-47Ms were delivered to the 56th Fighter Group,
and were responsible for all four of that group's jet shoot-downs. Twelve were lost in operational
crashes with the 56th Group resulting in 11 deaths, two after VE Day, and two (44-21134 on 13
April 1945 and 44-21230 on 16 April 1945) were shot down in combat, both by ground fire.
The second YP-47M (of the batch of four converted P-47Ds) was later fitted with new wings and
served as the prototype for the P-47N.
P-47N
The P-47N was the last Thunderbolt variant to be produced. It was designed as an escort fighter
for the B-29 Superfortress bombers flying raids on the Japanese home islands. Increased internal
fuel capacity and drop tanks had done much to extend the Thunderbolt's range during its
evolution, and the only other way to expand the fuel capacity was to put fuel tanks into the
wings. Thus, a new wing was designed with two 50 U.S. gal (190 l) fuel tanks. The second YP-
47N with this wing flew in September 1944. The redesign proved successful in extending range to
about 2,000 mi (3,200 km), and the squared-off wingtips improved the roll rate. The P-47N entered
mass production with the uprated R-2800-77(C) engine, with a total of 1,816 built.
The very last Thunderbolt to be built, a P-47N-25, rolled off the production line in October 1945.
Thousands more had been on order, but production was halted with the end of the war in
August. At the end of production, a Thunderbolt cost $83,000 in 1945 U.S. dollars. A total of
15,686 Thunderbolts of all types were built, making it second most produced American fighter of
all times—after the 16,766 P-51 Mustangs. A number of P-47s have survived to the present day,
and a few are still flying.
Operational history
US service
By the end of 1942 P-47Cs were sent to England for combat operations. The initial Thunderbolt
flyers, 56th Fighter Group, was sent overseas to join the 8th Air Force. Two Fighter Groups
already stationing in England began introducing the Jugs in January 1943: the Spitfire-flying 4th
Fighter Group, a unit built around a core of experienced American volunteers of the Eagle
Squadrons; and the 78th Fighter Group, formerly using P-38 Lightning.
Beginning in January 1943, Thunderbolt fighters were sent to the joint Army Air Forces – civilian
Millville Airport in Millville, New Jersey in order to train civilian and military pilots. they were
joined in August by an additional unit, the 312th Army Air Corps Base Unit at Dover Army Air
Force Base, Dover Delaware.
The first P-47 combat mission took place 10 March 1943 when the 4th FG took their aircraft on a
fighter sweep over France. The mission was a failure due to radio malfunctions. All P-47s were
refitted with British radios, and missions resumed 8 April. The first P-47 air combat took place 15
April with Major Don Blakeslee of the 4th FG scoring the Thunderbolt's first air victory (an FW-
190). On 17 August, P-47s performed their first large-scale escort missions, providing B-17
bombers with both penetration and withdrawal support of the Schweinfurt-Regensburg mission,
and claiming 19 kills against three losses.
By mid-1943, the Jug was also in service with the 12th Air Force in Italy, and it was fighting
against the Japanese in the Pacific with the 348th Fighter Group flying escort missions out of
Brisbane, Australia. By 1944, the Thunderbolt was in combat with the USAAF in all its
operational theaters, except Alaska.
Although the P-51 Mustang replaced the P-47 in the long-range escort role in Europe, the
Thunderbolt still ended the war with 3,752 air-to-air kills claimed in over 746,000 sorties of all
types, at the cost of 3,499 P-47s to all causes in combat.[11] In Europe in the critical first three
months of 1944, when the German aircraft industry and Berlin were heavily attacked, the P-47
shot down more German fighters than did the P-51 (570 out of 873), and shot down
approximately 900 of the 1,983 claimed during the first six months of 1944. In Europe,
Thunderbolts flew more sorties (423,435) than P-51s, P-38s and P-40s combined.
By the end of the war, the 56th FG was the only 8th Air Force unit still flying the P-47, by
preference, instead of the P-51. The unit claimed 677.5 air victories and 311 ground kills, at the cost
of 128 aircraft.[13] Lieutenant Colonel Francis S. Gabreski scored 31 victories,[14] including three
ground kills, Captain Bob Johnson scored 27 (with one unconfirmed probable kill leading to some
giving his tally as 28),[15] and 56th FG Commanding Officer Colonel Hubert Zemke scored 17.75
kills.[16] Despite being the sole remaining P-47 group in the 8th Air Force, the 56th FG remained
its top-scoring group in aerial victories throughout the war.
With increases in fuel capacity as the type was refined, the range of escort missions over Europe
steadily increased until the P-47 was able to accompany bombers in raids all the way into
Germany. On the way back from the raids, pilots shot up ground targets of opportunity, and also
used belly shackles to carry bombs on short-range missions, which led to the realization that the
P-47 could perform a dual-function on escort missions as a fighter-bomber. Even with its
complicated turbosupercharger system, its sturdy airframe and tough radial engine could absorb a
lot of damage and still return home. Some pilots readily chose to belly-land their burning
Thunderbolts rather than risk bailing out; there are instances of P-47s crash-landing after being
shot down, hitting trees and causing impacts severe enough to snap off wings, tail, and engine,
while the pilot escaped with few or no injuries.
The P-47 gradually became the USAAF's best fighter-bomber, normally carrying 500 lb (227 kg)
bombs, M8 4.5 in (115 mm) or 5 in (127 mm) High velocity aircraft rockets (HVARs, or Holy
Moses). From the invasion of Europe on 6 June 1944 to VE day on 7 May 1945, the Thunderbolt
units claimed destroyed: 86,000 railroad cars, 9,000 locomotives, 6,000 armoured fighting vehicles,
and 68,000 trucks.
Postwar service
The USAAF Strategic Air Command had P-47 Thunderbolts in service from 1946 through 1947.
The P-47 served with the Army Air Forces (United States Air Force after 1947) until 1949, and with
the Air National Guard until 1953, receiving the designation F-47 in 1948. P-47s also served as
spotters for rescue aircraft such as the OA-10 Catalina and Boeing B-17H.
The F-51 Mustang was used by the USAF during the Korean War, mainly in the close air support
role with the F-47 not being deployed to Korea. Since the Mustang was more vulnerable to being
shot down, (and many were lost due to anti-aircraft fire), some former F-47 pilots suggested the
more durable Thunderbolt should have been sent to Korea; however the F-51D was available in
greater numbers in the USAF and ANG inventories.
