For flight 18 (10 rockets) it was necessary to replace each bomb rack with two rocket racks. For flights 19 and 21, the tanks were loaded with 79 gallons of water, each, to simulate the weight of fuel.
D. The airplane was equipped with a Packard built Rolls Royce model V-17650-9 engine, equipped with water injection for use at war emergency powers exceeding 67" Hg. manifold pressure, a Bendix Stromberg PD-18C-3A carburetor, and a 11' – 1" diameter four-bladed Aero Products propeller H-20-162-29M5, design No. 86892.
E. All flights were made with wheels up, flaps neutral, canopy closed, mixture "run", and manual boost control. The airplane has a normal unpainted finish. All level flight power calibrations were run with the coolant shutter in the flush position. Climbs were run with the coolant shutter in automatic. All horsepower figures are based on power curves Nos. 2493 and 2494 dated 2 November 1945, furnished by the Power Plant Laboratory.
V Flight Characteristics
A. Taxiing and Ground Handling
The airplane has good ground handling characteristics. The tail wheel is steerable 6° either side of center, and is held securely in the steerable position when the control stick is in neutral or aft of neutral. When the control stick is held in the forward position, the tail wheel is full swiveling and brakes must be used for control and slow speeds. Forward visibility is not improved materially in this model when in the 3 point attitude, making "S" turns necessary for forward vision. Ground handling can be easily accomplished in cross-winds.
B. Take-off and Climb
Take-off characteristics are normal. The take-off power setting is 3000 rpm and 61" Hg. For short field operation and best obstacle clearance, 15 to 20 degrees of flaps should be used, rudder trim should be set 7° right, elevator 1° nose heavy, and the Aileron tab in the neutral position. The slowest take-off speed attempted was approximately 103 mph, indicated.
Sawtooth climbs indicated the best climb speed to be approximately 162 mph IAS for low blower and 154 mph IAS for high blower.
No extensive stability investigation was made. Aside from a slight tendency to "hunt" directionally above 400 mph IAS, the characteristics were good and no deviation from previously reported characteristics was noted.
D. Trim and Balance.
Trim tabs are located on all control surfaces. Any varaiation in airspeed and power or external configuration which require a change in trim in the normal operating range may be easily corrected. However, at the high manifold pressures approaching 90" Hg. where water injection is necessary, the elevator trim is inadequate and it is necessary to exert excessive forward pressure on the control stick to maintain level flight.
The airplane has good control characteristics throughout the speed range except for the insufficient nose down trim mentioned in the preceding paragraph.
The airplane is very maneuverable within the range of speed tested. The radius of turn is comparatively small and the rate of roll is high. No buffeting is encountered in tight turns until the stalling speed is approached.
G. Stalling Characteristics.
Stalling characteristics were good in all configurations. The stalls were not violent, the approach was easily controlled and recovery was easily accomplished in all cases. The airplane enters the stall gradually, giving the pilot a sensation of mushing instead of complete stall.
H. Spinning Characteristics.
I. Diving Characteristics.
Not investigated. See Memorandum Report No. TSCEP5E-1898.
J. High Altitude Trials.
Under test conditions, the pilot determined 36,000 ft. to be the maximum practical condition for cruising. At this altitude three satisfactory level flight points using 3000, 2700 and 2500 rpm were obtained. Above 36,000 ft. the maximum level flight indicated airspeed at normal rated rpm begins decreasing rapidly with altitude.
No serious difficulty with freezing of trim tabs or other low temperature conditions were encountered.
K. Approach and Landing.
The approach is normal, the landing flaps operate quickly and there is very little tendency to float. Visibility is good with the gear down and is increased slightly when the flaps are lowered. Normal landing speed is approximately 102 mph IAS, normal speed for the glide is between 120 and 125 mph. The P-51H is easily controlled on the landing roll with the steerable tail wheel or brakes and has no ground looping tendencies. Final trim tab settings (power off) and landing is 2° right rudder and 9° nose up elevator.
L. Noise and Vibration.
Noise level is normal and not objectionable except when using over 74" Hg., MP. Most of the noise is caused by the short exhaust stacks just forward of the pilot. Vibration is slight above 420 IAS, below that it is negligible. There is little buffeting of the controls except with gear and flaps down. Vibration increases below 2000 rpm.
M. Pilot’s Report on Vision and Cockpit Layout.
The visibility in taking, take-off and climb is normal for single engine aircraft. In the air, in level flight, visibility for combat and cross country is good. The visibility on approach for landing is satisfactory. There are no distortions in the side windshield, canopy, or bullet proof glass. The P-51H is equipped with the standard AAF bucket type seat. Shoulder and elbow room is sufficient. Rudder pedals are in a comfortable position, however, the control stick is mounted slightly forward of the desired position.
VI Performance Data
A. Airspeed Indicator Calibration.
The airspeed position correction was obtained by flying with the P-51D, AAF No. 44-74570 pacer airplane. The results of the calibration and the location of the impact and static pickups may be found by referring to Figure 1, Appendix I. All indicated airspeeds quoted in this report are corrected for instrument error only.
B. Altimeter Correction.
The altimeter calibration was calculated for the position error of the airspeed pickup and is presented in Figure 4, Appendix I.
C. Critical Altitude.
The critical altitudes for normal rated power climb (46" Hg., MP and 2700 rpm) are 17,400 ft. for low blower and 30,700 ft. for high blower. The critical altitudes for war emergency power climb (90" Hg., H2O and 3000 rpm) are 16,000 ft. for high blower and by extrapolation, approximately 2200 ft. for low blower.
D. Maximum Speeds, Coolant Shutters Flush, Wheels and Flaps Up.
1. Power required curves for the clean configuration at take-off gross weight of 9544 pounds are presented in Figure 8, Appendix I.
The maximum speeds under standard conditions are shown graphically in Figure 16a and are tabulated below:
2. Data at war emergency rating with water injection at 3000 rpm.