O-805/12AC
Franklin O-805 on display at the National Museum of the United States Air Force
Type	12-cylinder horizontally opposed piston engine
Manufacturer	Franklin Engine Company
First run	c.1945

The Franklin O-805 (company designation 12AC) was an American air-cooled aircraft piston engine, designed in the mid-1940s and was to be used in radio-controlled pilotless drones that were to be guided from an accompanying control plane. Due to project requirement changes and cancellations the engine was not produced.^[1]

A smaller displacement 12-cylinder Franklin engine of 1941 was known as the O-595 or 12AC-596.

Variants

O-805

12AC-806

450 hp (336 kW)0

12ACG-806 (XO-805-1)

456 hp (340 kW) at 3,200 rpm, geared to 0.632:1.

12ACGSA-806 (XO-805-3 and O-805-5)

500 hp (373 kW) at 3,200 rpm, supercharged and geared to 0.632:1 (XO-805-3), or to 0.587:1 (O-805-5).

O-595

12AC-596

300 hp (224 kW) at 2,600 rpm

12ACG-596

350 hp (261 kW) at 3,500 rpm

Applications (intended)

• Interstate XBQ-5
• Interstate XTD2R-1

Survivors

• There is an O-805-2 on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT ^[2]
• One surfaced and was sold privately in August, 2016, on eBay for US$8500.^[3]

Specifications (12ACGSA-806/XO-805-3)

General characteristics

• Type: 12-cylinder air-cooled horizontally opposed aircraft piston engine
• Bore: 4.625 in (117.5 mm)
• Stroke: 4.0 in (101.6 mm)
• Displacement: 806.4 cu in (13.2 L)

Components

• Valvetrain: OHV
• Cooling system: Air-cooled
• Reduction gear: 0.632

Performance

• Power output: 500 hp (373 kW) at 3,200 rpm