Franklin O-425 - Misplaced Pages

(Redirected from Franklin O-425-9) American piston aircraft engine

O-425/6AG/6V6
Type	Piston aircraft engine
National origin	United States
Manufacturer	Franklin Engine Company
First run	1944

The Franklin O-425 (company designation 6AG/6V6) was an American air-cooled aircraft engine that first ran in the mid-1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 425 cu in (7 L). The power output was between 240 hp (179 kW) and 285 hp (213 kW) depending on variant. The O-405-13 (6V6-300-D16FT) of 1955 was a vertically mounted, turbocharged and fan cooled version for helicopters.

Variants

6AG6-245: Geared propeller drive at 0.623:1, 245 hp (183 kW) at 3,300 rpm, (XO-425-5).

6AGS6-245: Supercharged and geared, 250 hp (186 kW) at 3,200 rpm, (XO-425-3).

6V6-245-B16F: Vertically mounted, fan-cooled helicopter version, 245 hp (183 kW) at 3,275 rpm, (XO-425-1).

6V6-300-D16FT: Vertically mounted, turbocharged, fan-cooled helicopter version, 285 hp (213 kW) at 3,275 rpm, (O-425-13).

O-425-1

O-425-2

O-425-3

O-425-5

O-425-9

O-425-13

Applications

Specifications (O-425-5)

Data from Aircraft engines of the World 1950.

General characteristics

Type: 6-cylinder air-cooled horizontally-opposed aircraft piston engine
Bore: 4.75 in (120.7 mm)
Stroke: 4 in (101.6 mm)
Displacement: 425.3 cu in (6.97 L)
Length: 47 in (120 cm)
Width: 33.3 in (84.6 cm)
Height: 30 in (76 cm)
Dry weight: 405 lb (184 kg)

Components

Valvetrain: 1 x exhaust and inlet OHV driven by pushrods and rockers
Fuel system: 1 x Bendix-Stromberg PS-780 up-draught carburetor with automatic mixture control
Fuel type: 80 Octane / US Army 2-103 all-purpose motor fuel
Oil system: Pressure system at 55 psi (380 kPa)
Cooling system: Air-cooled

Performance

Power output:

Take-off: 245 hp (183 kW) at 3,300 rpm
Normal: 240 hp (180 kW) at 3,200 rpm at sea level
Cruise: 168 hp (125 kW) at 2,840 rpm at sea level

Specific power: 0.58 hp/cu in (26 kW/L)
Compression ratio: 7.4:1
Specific fuel consumption: 0.51 lb/hp/h (0.086 kg/kW/ks)
Oil consumption: 0.015 lb/hp/h (0.0025 kg/kW/ks)
Power-to-weight ratio: 0.606 hp/lb (0.996 kW/kg)
Reduction gear: Planetary reduction gearing at 0.623:1

References

Wilkinson, Paul H. (1950). Aircraft engines of the World 1950 (8th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 156–157.

Gunston, Bill (2006). World Encyclopaedia of Aero Engines (5th ed.). Stroud: Sutton Publishing. ISBN 978-0-7509-4479-3.
Gunston, Bill (1989). World Encyclopaedia of Aero Engines (2nd ed.). Cambridge, England: Patrick Stephens Limited. ISBN 978-1-85260-163-8.
Gunston, Bill (1993). World Encyclopedia of Aircraft Manufacturers. Annapolis: Naval Institute press. ISBN 9781557509390.

Franklin aircraft engines

By displacement

Two-cylinder engines

By displacement	O-110 O-120
By company designation	2A-110 2A-120 2A4-45 2A4-49 2AL-112

Four-cylinder engines

By displacement	O-150 O-170 O-175 O-180 O-200 O-225 O-235
By company designation	4A-225 4A-235 4A4-100 4A4-75 4A4-85 4A4-95 4AC-150 4AC-171 4AC-176 4AC-199 4ACG-176 4AL-225 Sport 4

Six-cylinder engines

By displacement	O-265 O-300 O-315 O-335 O-350 O-405 O-425 O-500
By company designation	6A-335 6A-350 6A3 6A4 6A8-215 6AC-264 6AC-298 6AC-403 6ACV-245 6AG-335 6AG4-185 6AG6-245 6AGS-335 6AGS6-245 6AL-315 6AL-335 6AL-500 6ALV-335 6AS-335 6V-335 6V4 6V6-245-B16F 6V6-245 6V6-300-D16FT 6V6-300 6VS-335

Eight-cylinder engines

By displacement	O-400 O-540
By company designation	8AC-398 8ACG-398 8ACG-538 8ACGSA-538 8ACSA-538

12-cylinder engines

By displacement	O-595 O-805
By company designation	12AC-596 12AC-806

v t e United States military piston aircraft engine designation system
H (four-bank H-configuration inline)	H-1640 XH-2240 XH-2470 XH-2600 XH-3130 XH-3730 H-4070
IV (inverted-V inline)	IV-1430 IV-2040 IV-2220
L (single-bank inline)	L-330 L-365 L-375 L-390 L-410 L-440 L-510 L-825
O (opposed)	O-15 O-40 O-45 O-90 O-100 O-145 O-150 O-170 O-175 O-180 O-190 O-200 (C) O-200 (F) O-205 O-235 O-290 O-300 O-335 O-360 (C) O-360 (L) O-405 O-425 O-435 O-470 O-480 O-520 O-540 (F) O-540 (L) O-550 O-580 O-805 O-1230
R (radial)	R-250 R-265 R-270 R-370 (LB) R-370 (K) R-420 R-440 R-500 R-540 (W) R-540 (K) R-545 R-550 R-600 R-670 R-680 R-720 R-755 R-760 R-790 R-830 R-915 R-975 DR-980 R-985 R-1044 R-1300 R-1340 R-1454 R-1510 R-1535 R-1640 R-1670 R-1690 R-1750 R-1820 R-1830 R-1860 R-2000 R-2060 R-2160 R-2180 R-2600 R-2800 R-3350 R-4090 R-4360 XR-7755
V (upright-V inline)	V-720 V-1150 V-1237 V-1400 V-1440 V-1460 V-1510 V-1560 V-1570 V-1650 (P) V-1710 V-1950 V-3420
V (inverted-V inline)	V-770 V-1650 (L)
VG (inverted-V inline)	VG-1410
W (three-bank W-configuration inline)	W-2779
See also: X-1800 US military gas turbine aeroengines Piston engine configurations

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