The Jacobs R-755 (company designation L-4) is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States by the Jacobs Aircraft Engine Company.
Design and development
The R-755 was first run in 1933 and was still in production in the 1970s. With a bore and stroke of 5.25 in × 5 in (133 mm × 127 mm) the displacement was 757 cu in (12.4 L), power ranged from 200 hp to 350 hp (150 kW - 260 kW). The engine features steel cylinders with aluminum-alloy cylinder heads. An R-755E variant was developed for use in helicopters.
Variants
R-755A1The base-line direct drive production version. R-755A2300 hp variant. R-755A3Similar to A1 but with Scintilla magnetoes. R-755B1De-rated version of the R-755A to drive a fixed pitch airscrew. R-755B2De-rated version of the R-755A to drive a variable or controllable pitch airscrew. R-755EUp-rated engine with reduction gearing. R-755EHDeveloped to power the Jacobs Type 104 Gyrodyne.
Applications
Anahuac Tauro
Beechcraft Model 17 Staggerwing (B17L, C17L, E17L) Boeing-Stearman PT-18 Kaydet Cessna AT-17 Bobcat Cessna 195 Funk F-23 Grumman G-164 Ag Cat Kellett KD-1 Lascurain Aura Morane-Saulnier MS.505 Criquet Waco F series (YMF, YPF) Waco Custom Cabin series (YOC, YQC) Waco Standard Cabin series (YKC, YKC-S, YKS-6) Waco PG-3 (twin-engined powered version of Waco CG-15 glider, prototype only)
Engines on display
A preserved Jacobs R-755 is on display at the Arkansas Air Museum. A Jacobs R-755 is on public display at the Aerospace Museum of California A preserved Jacobs R-755 is on display at Super T Aviation Academy in Medicine Hat, Canada. A restored Jacobs R-755A is on display at the House of Whitley.
Specifications (R-755-A1)