Franklin 6 series

Franklin 6 series engines

Type	6-cyl. horizontally opposed air-cooled piston engine
National origin	United States
Manufacturer	Franklin Engine Company
Variants	Franklin O-335

The Franklin 6 is a series of air-cooled aircraft and helicopter engines of flat-6 configuration, produced from the 1930s to the 1970s, that found widespread use in helicopters and some light aircraft, (Military designation;O-335, O-405 and O-425), as well as in the 1948 Tucker Sedan (with the engine modified for water cooling).

Variants

Data from:^[1]^[2]

6A-335: 180hp@2800rpm-200@3100; 1963-1976
6A-350: 205hp@2800rpm-235@3200; 1965-2002
6A4-125: 125hp@2200rpm; 1945-1949
6A4-130: 130hp@2200rpm; 1945-1949
6A4-135: 135hp@2450rpm; 1945-1949
6A4-140: 140hp@2375rpm; 1945-1949
6A4-145: 145hp@2600rpm; 1945-1949
6A4-150: 150hp@2600rpm; 1945-1975
6A4-165: 165hp@2800rpm; 1947-1975
6A4-200: 200hp@3100rpm; 1952-1953
6A8-215: 215hp@2500rpm; 1945-1951
6AC-264: 110hp@2600rpm-120@2600;
6AC-298: 130hp@2600rpm -155@2930; 1941-1945
6AC-403: 200hp@2750rpm; 1942-1946
6ACG-264: 138hp@3100rpm
6ACG-298-P5: 160hp@3200rpm; 1941-1945;
6ACGSA-403: 250hp@3200rpm; 1942-1946
6ACGSA-403: 250hp@3200rpm; 1942-1946
6ACSA-403: 220hp@2750rpm; 1942-1946
6ACT-298: 150hp@3000rpm ; 1941-1945
6ACTS-298-K4: O-300-5; the O-300-7 produced 175@3000
6ACTS-298: 160hp@3200rpm; 1941-1945
6ACV-245: 245hp@3275rpm; 1944-1958
6ACV-298: 160hp@3250rpm; 1944-1946
6ACV-403: 235hp@3275rpm; 1942-1946
6ACV-403: 245hp@3275rpm; 1942-1946
6AG-335: 220hp@3400rpm; 1963-1976
6AG4-185: 185hp@3100rpm; 1947-1950
6AG6-245: 240hp@3200rpm, 245@3300 (TO)
6AGS-335: 260hp@3400rpm; 1963-1976
6AGS6-245: 250hp@3200rpm; 1944-1948
6AL-315: 175hp@N/Arpm; 1944-1945
6ALG-315: 175hp@N/Arpm; 1944-1945
6AS-335: 240hp@3200rpm; 1964-1976
6AS-350: 235hp@2800rpm; 1968-1996
6V-335-A: 210hp@3100rpm; 1956-1964
6V-335-A1A: 200hp@3100rpm; 1959-1964
6V-335-A1B: 200hp@3100rpm; 1959-1964
6V-335-B: 210hp@3100rpm; 1956-1964
6V-350: 235hp@3200rpm; 1964-1996
6V4-165: 165hp@N/Arpm; 1947-1950
6V4-178: 178hp@3000rpm; 1946-1960
6V4-200: 200hp@3100rpm; 1946-1970
6V6-245-B16F: 245hp@3275rpm; 1944-1958
6V6-300-D16FT: 285hp@3275rpm, 300@3275 + Boost (TO); 1955-1960
6VS-335: 225hp@3200rpm; 1959-1964
Franklin O-335: Military designation
Franklin O-405: Military designation for the Franklin 6-ACV-405
Franklin O-425: Military designation for the Franklin 6-AC-425

Applications

Data from:^[1]^[2]

Aero-Flight Streak-165
Aeronca 15AC Sedan
Bartlett LC-13A
Bell 47
Bell HTL
Bellanca 14-13
Bunyard BAX-3 Sportsman
C.L.A.S.S. BushCaddy L 164
Cessna 170
Cessna 172
Cessna 175
Convair 106 Skycoach
Convair L-13
Culver XPQ-15
Culver XTD3C-1
Doman LZ-1A
Doman LZ-2A Pelican
Fairchild XUC-86B
Fleetwings XBQ-1
Goodyear GA-1 Duck
Goodyear GA-2B Duck
H-13 Sioux
Hiller 360
Hiller H-23 Raven
Hiller HTE
Hiller UH-12B
Hirth Acrostar Mk.I
Jovair 4E Sedan
Kaiser Magic
Kellett XR-8
M-26 Iskierka
M-5-220C
Maule M-4
McCulloch HUM-1
McCulloch MC-4C
McCulloch YH-30
McKinnie 165
Omega BS-1
Piaggio P.136-L
Procair F.15D Picchio
PZL-Mielic M-20 Mewa
Republic RC-1 Thunderbolt
Republic RC-3 Seabee
Republic YOA-15
Seibel S-4B
SIAI-Marchetti S.205
Sikorsky HO5S
Sikorsky R-7
Sikorsky S-52
Sikorsky XR-6
Sikorsky YH-18
Socata MS 894 Commodore 220
Socata Rallye 220GT
Socata Silvercraft SH-4
Southern Aerocar
Stinson 108
Taylorcraft 15A
Temco TE-1B
Temco YT-35 Buckaroo
Van's RV-8
Waco Minerva 220
Waco Model W Aristocraft
Wagner Sky-Trac 1
Wagner Sky-Trac 3
Wagner Sky-Trac 4 Aerocar
Wittman Big X
Zenith CH-801

Specifications (6ACV-403)

Data from ^[3]

General characteristics

Type: 6-cylinder air-cooled horizontally opposed vertically mounted helicopter piston engine
Bore: 4.625 in (117.5 mm)
Stroke: 4 in (101.6 mm)
Displacement: 403 cu in (6.60 l)
Width: 33.7 in (856.0 mm)
Height: 43.4 in (1,102.4 mm)
Dry weight: 458 lb (207.7 kg)

Components

Valvetrain: OHV, 1x inlet valve, 1x exhaust valve operated by pushrods
Fuel system: 2x Bendix-Stromberg PS-5C pressure updraught carburettors
Fuel type: 80 Octane gasoline
Oil system: 120 S.U. secs (25.1 cs) grade pressure fed at 55 psi (379,212 Pa), dry sump
Cooling system: Air-cooled
Delco-Remy 108567-541 vertical geared electric starter motor

Performance

Power output: 245 hp (182.7 kW) at 3,275 rpm for take-off
Specific power: 0.61 hp/in³ (27.758 kW/l)
Compression ratio: 7:1
Specific fuel consumption: 0.5 lb/hp/hr (0.304 kg/kW/hr, 225 US.gal/hp/hr) cruising
Oil consumption: 0.015 lb/hp/hr (0.09 kg/kW/hr, 7 US.gal/hp/hr) cruising
Power-to-weight ratio: 0.357 hp/lb (0.587kW/kg)

Notes

↑ 1.0 1.1 "Franklin, Aircooled Motors, Doman-Marks (US); Franklin Aircraft Engines, WSK-PZL (Poland) Part 2: O-315 through O-805".
↑ 2.0 2.1 Erickson, Jack. "Franklin, Aircooled Motors, Doman-Marks (US);Franklin Aircraft Engines, WSK-PZL (Poland) Part 2: O-315 through O-805".
↑ Wilkinson, Paul H. (1945). Aircraft Engines of the world 1945. New York: Paul H. Wilkinson. pp. 94–95.

References

Wilkinson, Paul H. (1945). Aircraft Engines of the world 1945. New York: Paul H. Wilkinson. pp. 88–89.
Erickson, Jack. "Franklin, Aircooled Motors, Doman-Marks (US); Franklin Aircraft Engines, WSK-PZL (Poland) Part 1: Introduction and O-110 through O-300".
Erickson, Jack. "Franklin, Aircooled Motors, Doman-Marks (US);Franklin Aircraft Engines, WSK-PZL (Poland) Part 2: O-315 through O-805".

2A-110
2A-120
2A4-45
2A4-49
2AC-596
2AL-112
4A-225
4A-235
4A4-100
4A4-75
4A4-85
4A4-95
4AC-150
4AC-171
4AC-176
4AC-199
4AC
4ACG-176
4ACG-199
4AL-225
6A-335
6A-350
6A3
6A4
6A4-125
6A4-130
6A4-135
6A4-135
6A4-145
6A4-150
6A4-165
6A4-200
6A8-215
6AC-264
6AC-298
6AC-403
6ACG-264
6ACG-298
6ACGA-403
6ACGSA-403
6ACSA-403
6ACT-298
6ACTS-298
6ACV-245
6ACV-298
6ACV-403
6AG-335
6AG4-185
6AG6-245
6AGS-335
6AGS6-245
6AL-315
6AL-335
6AL-500
6ALG-315
6ALV-335
6AS-335
6AS-350
6V-335-A
6V-335-A1A
6V-335-A1B
6V-335-B
6V-335
6V-350
6V4
6V4-165
6V4-178
6V4-200
6V4-335
6V6-245-B16F
6V6-245
6V6-300-D16FT
6V6-300
6VS-335
8AC-398
8ACG-398
8ACG-538
8ACGSA-538
8ACSA-538
12AC-596
12AC-806
12ACG-596
12ACG-806
12ACGSA-806
Franklin O-175
Franklin O-180
Franklin O-200
Franklin O-300
Franklin O-335
Franklin O-405
Franklin O-425
Franklin O-540
Franklin O-805
Sport 4

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