Franklin O-405

The Franklin O-405 (company designation 6AC-403) was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 405 cu in (6.64 L). The power output was between 200 hp (149 kW) and 250 hp (186 kW) depending on variant. The O-405-9 (6ACV-403) was a vertically mounted, fan cooled version for helicopters.

O-405/6AC-403
Type	Piston aircraft engine
National origin	United States
Manufacturer	Franklin Engine Company
First run	1942

Variants

6AC-403 (XO-405-1)

200 hp (149 kW) at 2,750 rpm

6ACSA-403 (XO-405-3)

Supercharged, 220 hp (164 kW) at 2,750 rpm

6ACGSA-403 (O-405-5)

Supercharged, geared propeller drive at 0.632:1. 250 hp (186 kW) at 3,200 rpm

6ACV-403 (O-405-9)

Vertically mounted, fan-cooled helicopter version, 245 hp (183 kW) at 3,275 rpm

Applications

• Culver XPQ-15
• Doman LZ-1A
• Doman Pelican
• Fairchild XUC-86B
• Fleetwings XBQ-1
• Kellett XR-8
• Sikorsky R-6

Specifications (6AC-403/XO-405-1)

Data from

General characteristics

• Type: 6-cylinder air-cooled horizontally opposed aircraft piston engine
• Bore: 4.625 in (117.5 mm)
• Stroke: 4.0 in (101.6 mm)
• Displacement: 403.2 in³ (6.6 L)
• Dry weight: 405 lb (184 kg)

Components

• Cooling system: Air-cooled

Performance

• Power output: 200 hp (149 kW) at 2,750 rpm

See also

Comparable engines

• Continental Tiara 6-260

Related lists

• List of aircraft engines

References

Notes

Bibliography

• Gunston, Bill. (1986) World Encyclopedia of Aero Engines. Patrick Stephens: Wellingborough. p. 57