In the entire history of military aviation, there has never been an
airplane that could match the P-47 Thunderbolt for ruggedness and
dependability. It was by far the largest and heaviest single-engined
fighter that had been built. Shown above is the XP-47B Thunderbolt prototype.
In the entire history of military aviation, there has never been an airplane
that could match the P-47 Thunderbolt for ruggedness and dependability. The
pilots who flew it into combat called it "The Unbreakable" and "The plane
that can do anything." They were not far from wrong.
P-47's often came back from combat shot full of holes, their wings and
control surfaces in tatters. On one occasion a Thunderbolt pilot, Lieutenant
Chetwood, hit a steel pole after strafing a train over Occupied France. The
collision sliced four feet off one of his wings--yet he was able to fly
back safely to his base in England.
The story of the P-47 began in the summer of 1940. At that time Republic
was building the P-43 Lancer and had plans to produce a lightweight
fighter, designated the P-44 Rocket. In view of combat experience in
Europe, however, the Air Corps decided that if the United States became
involved in the war something larger and better than the P-44 would
be required.
Alexander Kartveli, Republic's chief engineer, quickly prepared a rough
sketch of a new fighter. It was a daring concept. He planned to use the new
Pratt & Whitney Double Wasp ,
2,000 h.p. XR-2800-21 eighteen-cylinder
two-row radial engine. It which was largest and most powerful aircraft engine ever
developed in the United States. He also envisioned that his plane would have
eight .50-caliber machine guns and enough armor plating to protect the pilot
from every direction. These features added up to an airplane weighing about
4,000 pounds more than any existing single-engined fighter.
Without such power of the new 2,000 h.p.
Pratt & Whitney Double Wasp ,
Kartveli could see no way of meeting the performance and load
carrying demands being made by the U.S.A.A.F. From an engineering standpoint,
the requirements presented some enormous problems, but far more problems
were presented by the engine. The first of these was the need for an
efficient super-charging duct system that would offer the least interrupted
airflow. Kartveli therefore adopted the unorthodox method of designing this
feature first and then building up the fuselage around it; the large
turbo-supercharger was stowed internally in the rear fuselage, with the
large intake for the air duct mounted under the engine, together with the
oil coolers. Exhaust gases were piped back separately to the turbine and
expelled through a waste gate in the bottom of the fuselage, and ducted air
was fed to the centrifugal impeller and returned, via an intercooler, to the
engine under pressure. Surprisingly, all this ducting of gases under
temperature and pressure did not prove very vulnerable in combat, for the
fighter was to become renowned for its ability to absorb battle damage and
return home.
The P47D-11-RE Thunderbolt with belly shackles for a 500 lb. bomb or
drop tank. A total of 12,602 P-47D's were built. The supercharging outlet
is apparent in this view as well as the characteristic razor back spine.
The new design was approved, and Republic began work on the first test model. The XP-47B
was ready in just eight months and was taken up for its first test flight on May 6, 1941. It proved
to be an outstanding success, and was able to do everything Kartveli had hoped, plus more. Its
speed of 412 miles per hour was even higher than expected.
The conventional three-bladed propeller could not efficiently utilize the
power of the new engine
and a four-bladed propeller was adopted. Although this propeller was an admirable solution to the
power gearing of the engine, there remained the problem of providing sufficient ground clearance
for its 12-foot diameter. If a conventional undercarriage were to be employed its suspension
would have been too far outboard to permit the wing installation of the guns and ammunition
requested by the U.S.A.A.F., and therefore Republic had to design a telescopic landing gear
which was nine inches shorter when retracted than when extended. Numerous other problems
were to be faced in absorbing the loads and stresses which would be imposed when a battery of
eight 0.5-in. guns (a phenomenal heavy armament for that time) was fired simultaneously, and in
providing the necessary tankage for the quantities of fuel stipulated to make the machine the first
true single-engined strategic fighter. Thus, it was only to be expected that when the first
prototype, the XP-47B Thunderbolt, made its first flight, on May 6, 1941, it dwarfed not only its
pilots but all previous fighters and, with a loaded weight of 12,086 lb., turned the scales at more
than twice the weight of most of its contemporaries.
The prototype Thunderbolt first took to the air on May 6,1941. Production
began with the P-47B, which entered United States Army Air Force service in
November 1942, first becoming operational with the Eighth Air Force
stationed in the UK on April 8,1943. The P-47B's range was not really good
enough for escort duties, and its maneuverability was poor, but at least it
offered a measure of real protection to the Allied bombers which had
previously suffered very heavy losses.
To increase the tempo of flight development of the XP-47B such leading test pilots as Colonel Ira
C. Eaker were employed, and at one time it was hoped that the design could benefit from combat
testing with the R.A.F. in the Middle East. Production difficulties caused General "Hap" Arnold
to notify the British Air Ministry, in September 1941, that it was considered inadvisable to do this
until various teething troubles were eradicated, and an optimistic estimate of May 1942 was
established as a target date for the Thunderbolt to be combat ready. This was eventually to prove
almost a year out. Numerous problems soon presented themselves as the XP-47B test program
advanced. At altitudes above 30,000 feet ailerons "snatched and froze", the cockpit canopy could
not be opened and control loads became excessive.
773 production versions were ordered. But this was only the beginning.
Before the war was over, a total of 15,579 Thunderbolts was built, about
two-thirds of which reached operational squadrons overseas.
The fastest model was the XP-47J, which did not go into
production. On August 4, 1944, this plane reached a speed of 504 miles
per hour. The razorback was cut away to improve rearward cockpit
visibility.
When, in January 1943, the U.S.A.A.F.'s 56th Fighter Group arrived in the
United Kingdom with its massive Republic P-47 Thunderbolts, R.A.F.
Spitfire fighter pilots banteringly suggested that their American
colleagues would be able to take evasive action when attacked by undoing
their harnesses and dodging about the fuselages of their huge mounts. The
Thunderbolt was certainly big. In fact it was the largest and heaviest
single engined single-seat fighter ever built! But sheer size was not to
prove detrimental to the Thunderbolt's subsequent operational career.
The first tasks of the Thunderbolt, which began on April 8, 1943, were high-altitude escort duties
and fighter sweeps in which the new aircraft acquitted itself well, despite the inexperience of its
pilots. It was soon discovered that the heavy Thunderbolt could out dive any Luftwaffe, or, for
that matter, Allied, fighter, providing a decisive method of breaking off combat when necessary,
but at low and medium altitudes it could not match the rate of climb or maneuverability of
German fighters. One shortcoming, which was even more marked in other Allied fighters, was
that of insufficient range to permit deep penetration into Germany, but means were already being
sought to add to the P-47B's 307 U.S. gallons of internal fuel. At the time of the Thunderbolt's
European debut radial-engined single-seat fighters were a rarity, the only other such fighter
operational in Europe being the
Fw 190A.
To prevent confusion between the two fighters of the
opposing sides the engine cowlings of the Thunderbolts were painted white, and white bands were
painted around the vertical and horizontal tail surfaces--an appropriate comment on recognition
standards appertaining at that time, as it would seem impossible to mistake the sleek and
beautifully-contoured German fighter for the portly Thunderbolt.
By mid-1943 improved P-47Cs were becoming available, with external fuel
tanks to increase range and a longer fuselage to improve maneuverability.
Next came the major production version, the P-47D, and then P-47Gs, and
P-47Ms with more powerful engines, giving a maximum speed of 756 km/h
(470 mph). They were used for anti V1 Flying Bomb duties.
The final version, the P-47N, was built primarily for use against the
Japanese. The fastest model was the XP-47J, which did not go into
production. On August 4, 1944, this plane reached a speed of 504 miles
per hour. Production plans were shelved in favor of another P-47
development, the Republic XP-72.
P-47's flew more than 546,000 combat sorties between March 1943 and
August 1945, destroying 11,874 enemy aircraft, some 9,000 locomotives, and
about 6,000 armored vehicles and tanks. Only 0.7 per cent of the fighters of
this type dispatched against the enemy were to be lost in combat.
The final version, the P-47N, was built primarily for use against the
Japanese in the Pacific theater. Shown is a P-47N-1-RE fitted with
a bubble canopy.
Specification (P-47D-25-RE Thunderbolt)
Powerplant:
One Pratt & Whitney Double Wasp ,
XR-2800-21 eighteen-cylinder
two-row radial engine developing 2,000 h.p. for take-off and 2,300 h.p. at 31,000 ft.
with turbo-supercharging.
Dimensions:
Length: 36 ft. 1.25 in. (11.01 m)
Height: 14 ft 2 in (4.32 m)
Wing span: 40 ft. 9.25 in (12.43 m)
Weights:
Empty: 10,700 lb. (4,858 kg)
Operational: 19,400 lb (8,807 kg)
Performance:
Maximum speed: 428 mph (689 km/h)
Service ceiling: 42,000 ft. (12,810 m)
Range: 925 miles (1,488 km)
Armament: Six or eight 0.5-in. wing-mounted Browning machine-guns
with 267 or 425 rounds per gun and up to 2,500 lb. of bombs or ten 5-in.
HVAR missiles.