AAM Jacobs Engines
| 1st Run |
Brand | Name | Model | HP | Weight | Built | |
| 1933 | Jacobs | L-4 | R-755 | 245 | 505 | Used on AAM Waco YKC | |
| 1933 | Jacobs | L-4 | R-755-9 | 245 | 505 | Engine stand, Orange Cowl, ASM 92-21-11 | |
| 1933 | Jacobs | L-4MB | Jacobs3 | 245 | 505 | Air filter, plenum, engine mount, red pallet, Odom Hangar | |
| 1933 | Jacobs | L-4 | Jacobs4 | 245 | 505 | On engine mount, white plywood, red pallet, Odom Hangar |
Jacobs Engines
Jacobs Engines
| Wikipedia
- Jacobs Aircraft Engine Company enginehistory.org - Jacobs Bomber Command Museum.ca - Jacobs Engines All are seven-cylinder, air-cooled, radial engines |
||||||
| Mod | Model | 1-Run | Bore | Stroke | HP | Notes |
|---|---|---|---|---|---|---|
| L-4 | R-755 | 1933 | 5.25 in | 5.0 in | 200 hp to 350 hp (150 kW - 260 kW) | Used on AAM Waco YKC Wikipedia - Jacobs R-755 |
| L-5 | R-830 | 1935 | 5.5 in | 5.0 in | Takeoff power ≈285 hp (212 kW) | Used on AAM Beech 18 Wikipedia - Jacobs R-830 |
| L-6 | R-915 | 1936? | 5.5 in | 5.5 in | 330 hp (246 kW) at 2,200 RPM at sea level | Used on: Beechcraft 18 Wikipedia - Jacobs R-915 |
Jacobs R-755 (L-4) Engine
Jacobs R-755
| First Run: | 1933 | |
|---|---|---|
| Number Built: | ||
| General Characteristics | ||
| Type: | Seven cylinder air-cooled radial | |
| Bore: | 5.25 in | 133 mm |
| Stroke: | 5.0 in | 127 mm |
| Displacement: | 757 cu in | 12.4 l |
| Length: | 27.25 in | 692 mm |
| Diameter: | 44 in | 1,188 mm |
| Dry weight: | 505 lb | 229 kg |
| Components | ||
| Valvetrain: | 1 inlet and 1 exhaust valve per cylinder | |
| Fuel system: | 1 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: | 245 hp (183 kW) at 2,200 rpm | |
| Specific power: | 0.32 hp/in³ | |
| Power-to-weight ratio: | 0.48 hp/lb at cruising rpm | |
Jacobs R-755 (L-4) Engine
On engine stand, orange cowl
TMA 76-14, ASM 92-21-11
Jacobs Aircraft Engine
Air Force Model R-755-9
Ser# J-024573
Right hand propeller
Data plate below hub
Jacobs R-755 (L-4) Engine
Air filter, plenum, engine mount, red pallet, Odom Hangar
Jacobs Aircraft Engine
Air Corps Model L-4MB
MFG’S. No. 12364
Accepted 5-16-42
Bill Maloney - Canadian Warplane Heritage Museum Jacobs L4MB
Jacobs Engine
Jacobs R-755 (L-4) Engine
On engine mount, white plywood, red pallet, Odom Hangar
This engine is right next to a Jacobs R-755 (L-4) engine that has a data plate identifying the model.
The other engine has a data plate, air filter and plenum, ignition wires, baffling between the cylinders, Ignition system wiring, and an exhaust system. This engine doesn’t.
One big difference between the L-4 engine and the two other larger engines is the cylinder bore diameter. It is a quarter of an inch larger in the bigger engines.
I compared the cylinders between the engine casting and the cylinder heads. Between the two engines, the cylinders were the same height, same diameter, had the same number of cooling fins, and the depth of the fins was the same. After this comparison, I think that this is a Jacobs R-755 (L-4) engine.
