Siemens-Halske Sh.III
Sh.III | |
---|---|
A Siemens-Halske Sh.III at the Museo Storico dei Motori e dei Meccanismi in, Palermo, Italy | |
Type | Counter Rotary engine |
National origin | Germany |
Manufacturer | Siemens-Halske |
Major applications | Siemens-Schuckert D.III and D.IV |
Number built | approx 1,200 |
Developed from | Siemens-Halske Sh.1 |
The Siemens-Halske Sh.III was an 11-cylinder, air-cooled counter rotary engine developed in Germany during World War I.[1] The engine was a development of the earlier 9-cylinder Siemens-Halske Sh.I.[2]
Design
The Siemens-Halske Sh.III was an 11-cylinder counter
The crankshaft was driven at 900 rpm via a set of
The counter rotary design allowed the engine to achieve the benefits of a high-power density from a high rotational speed while the propeller operated at a slower speed optimised for its design. By the end of WW1, operating the propeller at a slower speed than the engine had become normal practice for inline and V block engines but had proved difficult to accomplish on rotary engines.[1]
Additional benefits of the counter rotary design were lower aerodynamic losses[1] and reduced gyroscopic forces as the net cylinder rotational speed was reduced when compared to a conventional rotary of similar power output.[1][2]
Unlike most rotary engines the Sh.III had a throttle which could reduce engine speed to 350 rpm.[2]
The Sh.III was initially designed with a power output of 160 hp. A later variant, the Sh.IIIa, had a power output of 200 hp with some examples developing as much as 240 hp.[2]
In operation the Sh.III suffered from poor reliability. The engine tended to overheat as the relatively slow rotation of the cylinders limited cooling air flow. Additionally, seizures of the engine were caused by poor lubrication as the Germans did not have access to castor oil[1][2] which was one of the few oils that could retain its properties after being mixed with gasoline.[1][3]
Aircraft
- Albatros H.1
- Albatros D.XI
- Pfalz D.VII
- Pfalz D.VIII
- LFG Roland D.IX
- LFG Roland D.XVI
- Siemens-Schuckert D.II
- Siemens-Schuckert D.III
- Siemens-Schuckert D.IV
- Siemens-Schuckert D.VI
Specifications
Data from Airplane Engine Encyclopedia[4]
General characteristics
- Type: 11-cylinder counter rotary engine
- Bore: 124 mm (4.9 in)
- Stroke: 140 mm (5.5 in)
- Displacement: 18.6 L (1,140 cu in)
- Dry weight: 195 kg (430 lb)
Performance
- Power output: 120 kW (160 hp) [up to a maximum of 180 kW (240 hp)][2]
- Power-to-weight ratio: 0.616 kW/kg (0.375 hp/lb)
See also
References
Further reading
- Gray, Peter; Thetford, Owen (1970). German Aircraft of the First World War (2nd ed.). London: Putnam. ISBN 0-370-00103-6.
External links
- Idflieg.com's Siemens Sh.III engine photos, by Andi Szekeres
- Siemens Sh.III displayed at Museo Storico dei Motori e dei Meccanismi, University of Palermo (in Italian)
- Front view and rear view CAD-based animations of Sh.III internal engine components
- YouTube 30 May 2020 video of Mikael Carlson's authentic Pfalz D VIII biplane reproduction on its maiden flight, with restored and flightworthy Sh III engine