Continental A40

Design and development

The 37 hp (28 kW) A40 was introduced in the depths of the Great Depression. At the time there were a number of small engines available but all suffered from either high cost, complexity, or low reliability. The A-40 addressed all those shortcomings and was instrumental in the production of light aircraft in the difficult economic constraints of the period. The A-40-4 introduced an increase in power to 40 hp (30 kW). The engine later inspired the A-50 and subsequent engines.

The A40 featured single ignition until the A-40-5 version, which introduced dual ignition. All engines in this family have a 5.2:1 compression ratio and were designed to run on fuel with a minimum octane rating of 73.

The entire family of engines had its certification terminated on 1 November 1941. Engines produced before that date are still certified, but none can be produced after that date.

Variants

A40

Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)

A40-2

Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)

A-40-3

Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg) Featured cadmium-nickel connecting rod bearings.

A40-4

Single ignition, 40 hp (30 kW) at 2575 rpm, dry weight 144 lb (65 kg), Steel backed connecting rod inserts

A40-5

Dual ignition, 40 hp (30 kW) at 2575 rpm, dry weight 156 lb (71 kg)

Applications

Aeronca KC

Arup S-2

Piper J-2 Cub

Piper J-3 Cub

Porterfield Collegiate

Rose Parakeet

Taylor E-2 Cub

Taylorcraft A

Welch OW-5M

Engines on display

Old Rhinebeck Aerodrome

Specifications (A40-5)

Data from Type Certificate Data Sheet 72, Jane's 1938

General characteristics

Type: 4-cylinder air-cooled horizontally opposed aircraft piston engine

Bore: 3.125 in (79.3 mm)

Stroke: 3.75 in (95.3 mm)

Displacement: 115 cu in (1.9 L)

Length: 27.9375 in (710 mm)

Width: 26.4375 in (672 mm)

Height: 20.4375 in (519 mm)

Dry weight: 154 lb (69.9 kg) dry with carburrettor and magnetos

Components

Valvetrain: One intake and one exhaust side-valve per cylinder with a flathead valve design.

Fuel system: CMC Stromberg NA-82 carburetor

Fuel type: minimum 73 octane

Cooling system: Air-cooled

Performance

Power output: 40 hp (30 kW) at 2,575 rpm

Specific power: 0.35 hp/(cu in) (15.3 kW/L)

Compression ratio: 5.2:1

Specific fuel consumption: 0.72 lb/(hp h) (0.439 kg/(kW h))

Oil consumption: 0.025 lb/(hp h) (0.0153 kg/(kW h))

Power-to-weight ratio: 0.28 hp/lb (0.45 kW/kg)