Jacobs R-915

R-915
Type	Radial engine
Manufacturer	Jacobs Aircraft Engine Company
Developed from	Jacobs R-755

The Jacobs R-915 or L-6 is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States, production started in 1936.^[1]

Design and development

The R-915 was effectively an enlargement of the R-755 with strengthened stressed parts. With a bore and stroke of 5.5 in × 5.5 in (140 mm × 140 mm) the displacement was 914 cu in (15 L), takeoff power was around 330 hp (246 kW). The engine features steel cylinders with aluminum-alloy cylinder heads. The R-915A4 variant features a drive shaft for autogyro use.

Applications

Engines on display

A preserved Jacobs R-915 is on display at the Nanton Lancaster Society.^[2]
A Jacobs L-6 is on display at the Canadian Museum of Flight^[3]

Specifications (R-915A1)

Data from Jane's^[4]

General characteristics

Type: 7-cylinder air-cooled radial piston engine
Bore: 5.5 in (140 mm)
Stroke: 5.5 in (140 mm)
Displacement: 914 cu in (15 L)
Length: 40 in (1,030 mm)
Diameter: 45.5 in (1,160 mm)
Dry weight: 555 lb (252 kg)

Components

Valvetrain: 2 valves per cylinder, pushrod-actuated, Sodium cooled exhaust valves
Fuel system: Single Stromberg NA-R7A carburetor
Fuel type: 73 octane
Oil system: One pressure pump, two scavenge pumps
Cooling system: Air-cooled
Reduction gear: Direct drive, right hand tractor

Performance

Power output: 330 hp (246 kW) at 2,200 RPM at sea level
Specific power: 0.36 hp/cu-in (16.4 kW/L)
Compression ratio: 6:1
Power-to-weight ratio: 0.6 hp/lb (1 kW/kg)

References

Notes

↑ Gunston 1989, p.85.
↑ Nanton Lancaster Society: Jacobs L-6 MB Retrieved: 23 July 2015
↑ The Canadian Museum of Flight - L-6 Retrieved: 31 January 2009
↑ Janes 1989, p.305.

Bibliography

Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1989. ISBN 0-517-67964-7

External links

Jacobs L-6 MB, Bomber Command Museum of Canada - Nanton Lancaster Society
FAA Type Data Certificate Sheet - R-915

Jacobs aircraft engines

Radial engines	R-755/L-4 R-830/L-5 R-915/L-6

United States military piston aircraft engine designation system

H (four-bank H-configuration inline)	H-1640 XH-2240 H-2470 XH-2600 XH-3130 XH-3730 H-4070

I (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-770 V-1150 V-1237 V-1400 V-1410 V-1440 V-1460 V-1510 V-1560 V-1570 V-1650 (L) V-1650 (P) V-1710 V-1950 V-3420

W (three-bank W-configuration inline)	W-2779

See also: X-1800 US military gas turbine aeroengines Piston engine configurations

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