Design and development
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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.[1][2][4]
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.[2][3]
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.[2][3]
- A40
- Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)[2]
- A40-2
- Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)[2]
- A-40-3
- Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)[2] Featured cadmium-nickel connecting rod bearings.[5]
- A40-4
- Single ignition, 40 hp (30 kW) at 2575 rpm, dry weight 144 lb (65 kg),[2] Steel backed connecting rod inserts
- A40-5
- Dual ignition, 40 hp (30 kW) at 2575 rpm, dry weight 156 lb (71 kg)[3]
Specifications (A40-5)
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Data from Type Certificate Data Sheet 72,[2] Jane's 1938[10]
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
Comparable engines
Related lists