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Kinner R-5 / R-53 / R-55 / R-56 / R-540


Kinner R-56 installed in a PT-22 Recruit


The Kinner R-5 is an American five cylinder radial engine for light general and sport aircraft of the 1930s. The R-5 was a development of the earlier Kinner B-5, with slightly greater power and dimensions. The main change was the increase in cylinder bore from 117 mm (4.625 in) to 127 mm (5 in) and an increase in cylinder stroke from 133.3 mm (5.25 in) to 139.7 mm (5.5 in). This led to a corresponding increase in displacement from 7.2 liters (441 cu in) to 8.8 liters (540 cu in).
The head of the R-5 Series 2 has approximately three times as much cooling fin area as previously used cylinder heads, having longer fins spaced closer together. A greater angle between inlet and exhaust valves results in a stronger head and provides additional metal between valve seats. Cylinder heads have rear exhaust ports and lugs are provided for support of cowling rings.
Enlarged intake passages and valves increase the efficiency and result in higher brake mean effective pressure.
Bearings have been increased in size. The crankshaft has been greatly strengthened by increased sections. The main and master rod bearings are of the copper lead steel-backed type. Master-rod sections have been enlarged and design altered to give a very much stronger rod with little increase in weight. Improved front cover provides additional strength and durability. All oil passages are contained in the engine.
Kinner R-5 Series 2
Rocker arms have a roller supported on needle bearings on valve end which reduces side thrust on valve and increases life of valve guides. High pressure grease lubrication is provided for the main roller bearing of the rocker arm and the rocker arm end of pushrods. Pushrod rocker arm adjusting screws are designed so that with their removal the pushrod can be withdrawn through the opening of the rocker arm for inspection.
The Kinner R-5 Series 2 employs a separate camshaft for each of the five cylinders. Each camshaft includes a simple spur gear driven by pinion gear on rear end of crankshaft at one-half engine speed.
Spur type magneto drive gears are driven by the cam gears. Oil pressure and scavenger pumps are driven by shafts keyed into slots in the ends numbers three and four camshafts, respectively.
Provision for Eclipse compressed air started and Eclipse Y150 direct electric starter, also generator and fuel pump drives are provided. Each accessory has its own mounting pad. Provision is made in oil sump for Cuno oil filter.
This engne may be fitted with battery ignition and two machine gun synchronising drives were available.
The R-5 was a rough running but reliable engine and the R-5 and its derivatives were produced in the 1,000s, powering many World War II trainer aircraft, its military designation R-540.


Kinner Sportwing
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N2T Tutor
Ryan PT-22 Recruit





Kinner R-5
Type: 5-cylinder air cooled radial
Bore: 5 in (127 mm)
Stroke: 5 1⁄2in (139.7 mm)
Displacement: 540cu in (8.85 L)
Length: 32.3in (820.4 mm)
Height: 45.6in (1,157 mm)
Dry weight: 330lb (149.6 kg)
Valvetrain: 1 inlet and 1 exhaust valve per cylinder
Fuel system: 1 Stromberg carburetor
Fuel type: 73 octane
Oil system: Dry sump
Cooling system: Air
Power output: 160hp at 1,850 RPM max/113hp at 1,800 RPM cruise
Compression ratio: 5.50:1
Power-to-weight ratio: 0.48 hp/lb


Kinner R-5 Series 2
Cylinders: 5 radial
Bore: 5 in
Stroke: 5.5 in
Displacement: 540
Power: 160 hp at 1850 rpm
Weight: 325 lb
Compression: 5.5-1
Ignition: 2 x Scintilla Magneto
Carburettor: Stromberg NA-R6
Crankshaft Prop end: No.1 SAE Standard




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