PROOF DEPARTMENT
TACTICAL COMBAT SECTION
ARMY AIR FORCES PROVING GROUND COMMAND
EGLIN FIELD, FLORIDA

FINAL REPORT
ON
TACTICAL SUITABILITY OF THE P-47C-1 TYPE AIRCRAFT
18 December 1942

          1.    OBJECT:

                 To determine the relative tactical value of the P-47C-1 type aircraft for combat service.

          2.    INTRODUCTION:

                 This test was authorized by letter from Headquarters Army Air Forces, dated April 9, 1942, signed by Muir Fairchild, Brigadier General, U. S. Army, Director of Military Requirements, giving blanket order to determine the tactical suitability of all new types of aircraft received at this station. This test was started October 27, 1942 and finished November 26, 1942.

                 a.    Description.    The articles tested were P-47C-1 type airplanes, Air Corps Serial Nos. 41-6127, 41-6128, and 41-6129.

          3.    CONCLUSIONS:

                 It is concluded that:

                 a.    The P-47C-1 is the best high altitude fighter aircraft now in production with regard to high speed, stability, pilot comfort, height and armament.

                 b.    The rate of climb is not as good as desired, which fact limits its suitability as a medium altitude fighter and as an interceptor.

                 c.    All weight in the structure and accessories not vital to operational use should be eliminated.

                 d.    The aircraft is pleasant and easy to fly. New pilots should have no trouble being checked out in it.

                 e.    The rate of aileron roll is the best found in any type of American fighter.

                 f.    The view over the nose is not great enough to allow desired deflection shooting.

                 g.    The demand type oxygen installation is satisfactory, but the service type mask with this installation is bulky, heavy, cumbersome and irritating to the pilot.

                 h.    It is dangerous to attempt to take-off with mixture control in full rich position.

                 i.    In a glide with engine idling, engine tends to load up and difficulty is encountered starting up engine again.

                 j.    The hook-up of the throttle, R.P.M., and turbo control handles to operate as one if desired is very satisfactory.

                 k.    With the present ceiling now obtainable with this aircraft, and the added height with new modifications, experiments should be pushed to perfect a pressurized cockpit on this type plane now.

          4.    RECOMMENDATIONS:

                 It is recommended that:

                 a.    If possible the gun sight be raised higher to allow the pilot a larger angle over the nose for deflection shooting, and a guns sight incorporating mirrors aiding view over nose be installed.

                 b.    A movable mixture control stop preventing mixture control being pushed into full rich position by mistake be installed.

                 c.    Every effort possible be made to increase the rate of climb.

                 d.    A flap system be installed which will allow the flaps to come down equally without use of flap equalizer valve.

                 e.    Until an automatic turbo control is perfected a red light be placed in a prominent position in the cockpit which will light if turbo overspeeds. This should be in addition to the turbo tachometer and not replace it.

                 f.    Six (6) high rate of fire .50 caliber machine guns be installed when perfected.

                 g.    Instructions be issued to caution all pilots not to make long power-off glides.

                 h.    A study be made to improve cooling of engine so that the excessively rich mixtures, now necessary, can be eliminated.

                 i.    Suitable flash hiders for the guns be installed before the plane is used for night fighting.

          5.    RECORD OF TEST:

                 This test was conducted according to the program, Proof Department, S. T. No. 4-42-2, this headquarters, dated June 30, 1942, a copy of which is attached as Inclosure No. 1.

          6.    DISCUSSION:

                 a.    Performance range and gas consumption. (See Inclosure No. 2 for table on speed and rate of climb.)

(1)    Speed -- This aircraft is superior in speed at all altitudes to any other type American fighter tested at this field. The speed trial figures are attached as Inclosure No. 3.
 
(2)    Rate of climb -- The low rate of climb if the P-47C-1 was the greatest fault found in the aircraft. If it were possible to give this aircraft a superior rate of climb, three-thousand feet (3,000) or better, it would make a good fighter at all altitudes. Although this aircraft has an excellent ceiling, the low rate of climb would prevent it from being a satisfactory interceptor with the present warning systems now available in most combat zones.
 
(3)    Maneuverability -- The P-47C-1 was flown in mock combat against the P-38F, P-39D1, P-40F, and the P-51.
 
(a)    It had superior rate of aileron roll at all speeds, and especially at high speed to all American fighter contemporary types, none could follow it in a fast reverse turn.
 
(b)    The turning circle of this aircraft was larger than any of the other types engaged in combat. The high wing loading makes the plane mush in all maneuvers controlled by the elevators, and this also causes high speed stall in tight turns.
 
(c)    It was slightly slower in acceleration from level flight at fifteen-thousand (15,000) than all types except the P-40F, which was decidedly slower, however, the distance gained in the initial acceleration was never greater than fifty (50) yards and the P-47C-1 rapidly overhauled and passed the other types. This test was with closed shutters and the liquid cooled engines rapidly overheated, the shutters had to be opened and the planes decreased a good deal in speed allowing P-47C-1 to run away rapidly. In push-overs with maximum manifold pressure the P-47 accelerated faster and drew away from all other types.
 
(d)    In testing the zoom ability of the P-47C-1 it was found that from level flight and dives, the zoom was comparable with the P-40F. The P-39D1, P-38F, and P-51 have greater zooming ability.
 
(e)    In close fighting the P-47C-1, due to its faster aileron roll, can quickly reverse turn and break off the combat almost at will. However, due to the large turning circle and low rate of climb, it is deemed inadvisable to attempt to dog fight with any type of enemy fighter now used in the combat area.

                 (b. was omitted)   

                 c.    Ceiling -- The service ceiling of this aircraft is approximately thirty-eight-thousand feet (38,000’). Combat ceiling approximately thirty-five-thousand feet (35,000’).

                 d.    Range -- For cruising and combat ranges see Inclosure No. 2.

                 e.    Flying Characteristics -- The take-off is normal with no bad characteristics. With the tail wheel slightly off the ground the plane will fly itself off.

(1)    The pilot feels at ease in this aircraft immediately after take-off. After fifteen (15) minutes feeling it out in the air, a pilot feels as if he really knows the plane. There are no bad characteristics that practice is needed to get used to. The plane is very stable in all directions. It has a nice feel on the controls from the ground up to thirty-eight-thousand (38,000’), the maximum height flown here on test. No mushiness in controls due to altitude is noticeable. The aileron control is light at all speeds, having the best aileron control of all modern American type fighters.
 
(2)    The stall and spin characteristics are normal with a good warning felt in the ailerons. Recoveries are made by normal procedure. (New pilots should be advised against making slow turns with wheels down (below 150) as aircraft loses altitude rapidly.) The plane lands easily and sticks very nicely to the runway having no tendency to bounce or skip. It rolls straight without attempting to swing or break in either direction. The plane will recover from stalls and spins by itself. The aircraft performs all normal acrobatics in a satisfactory manner. It has a good acceleration in level flight and excellent in dive. At five-hundred (500) m.p.h. indicated the plane is easy to fly and only a small movement of the trim tab is necessary to neutralize the controls.
 
(3)    The aircraft offers a very stable gun platform at all speeds and altitudes. All guns were fired at thirty-eight-thousand-five-hundred feet (38,500’), in a climbing turn, one-hundred-thirty-five (135) m.p.h., IAS. There were no ill effects in noticed performance of characteristics.

                 f.    Cockpit Arrangements -- The cockpit is clean with all instruments and switches arranged in an orderly manner. Levers, buttons and switches are all within easy reach and simple to operate. The engine and flight controls are normal with the exception of the controls and instruments dealing with the turbo supercharger.

                 g.    Cockpit Comfort -- The cockpit is large, roomy, comfortable, and well heated. It warms at high altitudes, no complaints having bee received from pilots. At thirty-eight-thousand feet (38,000’), with a free air temperature of approximately -50°C, the pilot flying in a leather flying jacket reported that the only discomfort felt was that his feet became slightly cold.

                 h.    The present armament is considered adequate, making it probably the heaviest armored single engine fighter in the world. If eight (8) .50 caliber guns are considered adequate for all conditions met in combat, it might be advisable to install six (6) high rate of fire .50 guns instead. This would still leave more fire power than now available in eight (8) standard rate of fire .50 caliber. However, the permanent installations should be left in plane, in case changes in armor design of enemy aircraft may call for additional fire power.

                 i.    Armor -- The armor protection is now considered satisfactory. However, firing tests are being conducted at this station to conclusively determine the adequacy of armor plate thickness and positioning, and a separate report will be submitted at the conclusion of the tests.

                 j.    Vulnerability of vital installation -- Vulnerability of this airplane is to be tested in the near future and as soon as test is completed, results will be forwarded.

                 k.    Visibility -- The pilot’s visibility forward, downward, sideways, and backward is excellent. A slight skid in either direction gives a view of the whole sky to the rear. The large engine naturally cuts off the visibility downward in front. The visibility as a whole seems slightly better than the standard fighter having the engine in front.

                 l.    Night Flying -- The subject aircraft is suitable for night flying, the only objection being the restricted view over nose in landing roll, but as previously stated the plane lands nicely and rolls in a straight line. The cockpit light is satisfactory. Airplane is unsuitable as night fighter, due to blinding effect of the gun flashes.

                 m.    Instrument Flying -- For a fighter type aircraft the instrument flying qualities are very good. The stability if the ship, the ease of trim, and the response of the controls make it simple to fly on instruments. The flight instruments are nicely arranged on top, center of instrument panel with no obstructions in from to peer around.

                 n.    Speed of servicing -- The Subject aircraft can be completely serviced (fuel, oil, coolant, oxygen, ammunition, and radio check) in twelve (12) minutes by using a crew of eight (8) men.

                        Four (4) armament men – twelve (12) minutes.
                        Two (2) servicing men – six (6) minutes.
                        Two (2) oxygen men – two (2) minutes.

                 (o. was omitted)

                 p.    Maintenance.

(1)    The regular fifty (50) hour inspection can be completed in approximately six (6) hours by using the optimum crew, or it can be completed in approximately eight (8) hours by a crew of two (2) men.
 
(2)    The most common maintenance difficulties were found to be:
 
(a)    Oil which was thrown from push rods and intake manifold came through cooling shutters and was blown into front of canopy.
 
(b)    The wires on electrical tachometer generators broke which caused rewiring.
 
(c)    Tail wheel tire walls were cracking, due to tires being weak and pilots trying to turn the ship while taxiing with tail wheel locked.
 
(d)    The cockpit was hard to keep clean, due to inability to clean corrugated cockpit floor.
 
(e)    It was difficult to obtain proper adjustment when bleeding master brake cylinder.
 
(f)    Difficulty was encountered in inspecting supercharger installations, due to lack of adequate and properly placed inspection plate.
 
(g)    Difficulty was encountered in adjusting sequence and also flap bleeder valves, due to smallness of inspection holes in top of wing.
 
(h)    Section of the main air duct had to be removed every time main gasoline tank was drained.
 
(i)    Trouble was experienced with the fuel gauges and fuel level light. The gauges come out of adjustment very easily and since the fuel level light is connected directly to the main fuel gauge, it is dependent on the accuracy of the main gauge for its proper functioning.
 
(j)    Difficulty was encountered in inspecting brake clearances on top of drum without removing wheel fairing.

                 q.    Recommendations on above difficulties:

(1)    That study be made of placing cooling shutters on side of motor cowl instead of on top.
 
(2)    That wire leads to electric tachometer be lengthened to take tension off of the leads.
 
(3)    That further study be made as to the weakness of sidewalls of tail wheel tire and pilots be instructed not to turn with tail wheel locked.
 
(4)    That a smooth cockpit floor be installed if possible to help keep cockpit free of dirt.
 
(5)    That a study be made to determine cause of difficulty in obtaining proper adjustment when bleeding master brake cylinder.
 
(6)    That an inspection plate twelve inches by twelve inches (12” x 12”) or large as possible be placed on the left-hand side of the fuselage near supercharger to facilitate inspection and repair.
 
(7)    That the inspection plates for sequence and flap bleeder valves on top of wings be enlarged to allow sufficient working room adjusting valves.
 
(8)    That the gas tank drain pipes be extended between exhaust and air intake ducts to facilitate draining tanks.
 
(9)    That the fuel gauges be corrected so that normal maneuvers will not cause them to get consistently out of adjustment. That the fuel level light be connected directly to tank in order that the light will go on when reserve is reached.
 
(10)    That inspection plates should be placed at end in the wheel fairing to permit better access to top brake clearance plates. That star gear cover should be put on top of brake drum similar to that on the bottom.

          7.    INCLOSURES:

                 Inclosure No. 1. - Test Program.
                 Inclosure No. 2. - Table of Speed and Rate of Climb.
                 Inclosure No. 3. - Speed Trial Figures.
 

WWII Aircraft Performance    P-47 Performance