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

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

XO-405-1 - 6AC-403

XO-405-3 - 6ACSA-403 (10.2:1 supercharger ratio)

O-405-3 - 6ACGSA-403

XO-405-5

O-405-7 - 6ACGSA-403

O-405-9 - 6ACV-403 verticla mount for H-6/R-6 & H-7/R-7 helicopters

O-405-11 - 6ACGSA-403

XO-425-1

Military designation for the Franklin 6ACV-425

O-425-3

O-425-5

for Convair L-13

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 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 cSt) 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/(sq in) (27.758 kW/L)
Compression ratio: 7:1
Specific fuel consumption: 0.5 lb/(hp h) (0.304 kg/(kW h), 225 US gal/(hp h)) cruising
Oil consumption: 0.015 lb/(hp h) (0.09 kg/(kW h), 7 US gal/(hp h)) cruising
Power-to-weight ratio: 0.357 hp/lb (0.587 kW/kg)

Notes

1 2 "Franklin, Aircooled Motors, Doman-Marks (US); Franklin Aircraft Engines, WSK-PZL (Poland) Part 2: O-315 through O-805".
1 2 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".