SUBJECT:     Comparitive Propeller Tests

SECTION:     Flight

SERIAL No.  FS-M-19-1523-A

A.    Purpose

        1.   To report results of flight tests of six four-bladed propellers installed on P-47B airplane. Tests were run at Republic Factory, Farmingdale, New York. Airplane equipped with Pratt and Whitney R-2800-21 engine with torque meter and with an exhaust driven turbo supercharger. Gross weight as tested was 12,620 pounds at 30.32 percent m.a.c. wheels up. Radio mast and antenna in place, and eight .50 caliber guns installed. All tests with wheels and flaps up and with mixture auto-rich.

        2.   Propellers, design Nos. 814-1C3-24A, 714-1C2-12, and 814-3C3-18 were fitted with cooling cuffs.

B.    Test results

        1.   High speed at 2000 torque meter b.h.p. at 2700 RPM at 5000 feet, 25,000, and at critical altitude for 2000 b.h.p. at 18,250 turbo RPM. Cowl flaps closed, intercooler and oil cooler shutters neutral.

	True Speed - MPH
	Curtiss					Ham. Std.
Altitude	12'2"	13'2"	13'6"	12'2"	12'2"	13'0"
Feet	714-1C2-12	814-1C3-24A	814-3C3-18	101348-12	101350-12	6501A-0
5,000	353	343	337	352	350	347
25,000	419	402	397	418	415	414
Critical Altitude	428 at 28,000 ft.	408 at 27,000 ft.	406 at 28,000 ft.	426 at 27,400 ft.	425 at 28,200 ft.	424 at 28,200 ft.

        2.   Climb data obtained with throttle wide open and turbo on to give either 2000 torque b.h.p. or 18,250 turbo RPM at 2700 engine RPM. Cowl flaps, oil cooler flaps, and intercooler flaps wide open.

	Rate of Climb - Ft./Min.
Propeller	10,000	15,000	20,000	*24,000	30,000
Curtiss 12'2"    714-1C2-12	2420	2350	2180	1960	1180
Curtiss 13'2"    814-1C3-24A	2600	2540	2400	2200	1320
Curtiss 13'6"    814-3C3-18	2610	2560	2400	2200	1410
Curtiss 12'2"    101348-12	2590	2530	2390	2180	1320
Curtiss 12'2"    101350-12	2600	2550	2405	2210	1300
Ham. Std. 13'    6501A-0	2700	2620	2460	2270	1400
Torque b.h.p.	2000	2000	2000	2000	1645
True Speed	185	201	218	233	250

               *Critical altitude for 2000 b.h.p. at 18,250 turbo RPM.
               Note: Above speeds are minimum speeds at which climbs could be run due to poor engine cooling. On a hot day it would not be possible to climb at these speeds. Airspeeds for maximum rate of climb are 10 to 15 MPH slower than above speeds.

        3.   Distance required to take-off from a concrete runway and clear a fifty foot obstacle with engine operating at 2700 RPM and mixture auto-rich.

Propeller	12'2" Curtiss Design No. 101348-12			13'2" Curtiss Design No. 101350-12
Flap setting	0	1/2	Full	0	1/2	Full
I.A.S. at T.O.	99	96	91	103	100	86
b.h.p.	1760	1770	1765	1750	1750	1735
Ground Roll	1425	1200	1000	1440	1200	1180
Distance to    clear 50 foot obstacle	2100	1935	1615	2080	1915	1750
Average of    No. of trials	3 of 4	3 of 4	2 of 4	4 of 4	3 of 4	2 of 3

        4.   Determination of airspeed and altimeter error with a Kollsman type D-1 airspeed head located with static holes 23-3/8 inches ahead of the leading edge of the left wing and 43 inches in from the tip and approximately one inch above the chord line.

Indicated Air speed m.p.h.	Water Column MPH	Calibrated Air speed MPH	Air speed Installation Error MPH	Altimeter Error at Sea Level Feet
310	308.0	320.0	-12.0	-215
290	290.5	299.0	- 9.0	-175
260	260.0	267.5	- 7.5	-145
230	229.5	236.5	- 7.0	-105
200	199.0	205.0	- 6.0	-  80
170	168.5	174.0	- 5.5	-  60