Jacobs R-755

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-755A1:The base-line direct drive production version.
 * R-755A2:300 hp variant.
 * R-755A3:Similar to A1 but with Scintilla magnetoes.
 * R-755B1:De-rated version of the R-755A to drive a fixed pitch airscrew.
 * R-755B2:De-rated version of the R-755A to drive a variable or controllable pitch airscrew.
 * R-755E:Up-rated engine with reduction gearing.
 * R-755EH:Developed 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.