Sunbeam Cossack
| Company type | Aero engine |
|---|---|
| Industry | Aerospace engineering |
| Founded | 1916 |
| Founder | Louis Coatalen |
| Products | Aero engines |
| Parent | Sunbeam |
|}
The Sunbeam Cossack was a British 12-cylinder aero engine that first ran in 1916, marking the beginning of a series of engines developed by Sunbeam.
Design and development
During the First World War, the Admiralty demanded more powerful propulsion systems for aircraft such as the Short Type 184 seaplanes, which were unable to carry torpedoes effectively with the existing Sunbeam Mohawk engines. The requirement specified a minimum power output of . In response, Sunbeam introduced the Cossack alongside Rolls-Royce’s Eagle engine.
Conceived by Louis Coatalen, the Cossack was a 60° V-12 design featuring twin overhead camshafts and four valves per cylinder. It had a bore of and a stroke of , generating at 2,000 rpm. The engine weighed and incorporated a 2:1 reduction gear to drive the propeller. Its construction combined aluminium alloy with cast-iron cylinder blocks and integrated heads arranged in sets of three cylinders.
Despite substantial orders, manufacturing progressed slowly; only eleven units were handcrafted and delivered between March and September 1916. After halting production of the Sunbeam Gurkha in October 1916, factory output increased to approximately thirty engines per month until production ended in December 1917, totaling 350 engines built.
The Sunbeam Cossack II introduced enhancements such as four magnetos and either compressed-air or manual starting mechanisms, rated at .
Towards the end of the war, British airship projects including the R36, R37, and R38 utilized the Sunbeam Cossack III. This variant featured a flywheel, options for hand or air starters, onboard engine controls with accessible magnetos for mechanics, water-cooled exhaust systems, and a speed governor. Its overhead camshafts were driven by gears connected to the crankshaft. Production was limited to fourteen units due to post-war cancellations of airship programs.
Amazon
Following Coatalen’s design principles, the Amazon was developed as a straight-six derivative of the Cossack. It retained the same bore and stroke dimensions of 110 x 160 mm, overhead camshaft configuration, four valves per cylinder, and cast-iron blocks arranged in groups of three. The engine produced at , weighed , and exhibited an impressive power-to-weight ratio. Nevertheless, its application was limited within Britain, primarily powering Coastal airships and some units supplied to the Imperial Russian Air Service. Of an order for 100 units, only 77 were completed while 23 were cancelled. A non-aviation version known as the Sunbeam Amazon II featured hand or compressed-air starters and employed a single magneto ignition system.
Saracen
Advancing his engine designs further, Coatalen developed the Sunbeam Saracen, a straight-six engine that increased bore size and utilized aluminium alloy cylinder blocks. With a bore of , it displaced . The Saracen delivered at 2,000 rpm through a 2:1 reduction gear. When submitted to the Internal Combustion Engine Committee under the National Advisory Committee for Aeronautics, it faced stiff competition from contemporaries such as the Beardmore 160 hp and Hispano-Suiza 8, resulting in no production orders beyond prototype stages.
Viking
To achieve greater power output, Coatalen designed the Sunbeam Viking, a W-18 configuration employing Cossack cylinder blocks arranged at 60° intervals between banks. This engine had a displacement of , producing at a propeller speed of 900 rpm. Although fifty units were ordered to power the large AD Seaplane Type 1000, only nine were completed; most were repurposed for motorboat use while forty-one orders were cancelled.
Matabele
The Sunbeam Matabele, the last engine derived from the Cossack series, maintained the aluminium alloy cylinder blocks and bore size introduced with the Saracen. This V-12 powerplant produced at 2,000 rpm through a 1.63:1 reduction gear from a displacement of . Two variants were available: the aviation-oriented Matabele I, equipped with four magnetos to provide dual ignition redundancy, and the non-aviation Matabele II, featuring two magnetos with a single ignition system. While mainly installed in Airco DH.4 bombers, it also found use in motorboats and high-speed racing cars. No Matabele engines were manufactured during World War I; however, prototypes and at least eight production models were completed after the war for various uses.
Sunbeam 1000 hp
The most notable application of the Matabele engine was in the Sunbeam 1000 hp land speed record vehicle, which was the first automobile to break the 200 mph barrier.
Following Segrave's record-setting run at with the Sunbeam Tiger, he realized that his lightweight racing car could not maintain its record against newer aero-engine-powered challengers. Due to financial constraints at S.T.D. Motors, further development was limited.
Two Matabele engines, originally installed in the Maple Leaf VII powerboat, were obtained from Sunbeam's Wolverhampton factory. It is reported that each engine in the Sunbeam 1000 HP had four magnetos, suggesting these were Matabele I variants.
On 29 March 1927, the Sunbeam became the first vehicle to exceed 200 mph. Although labeled "1000 HP," its actual power output was closer to 900 bhp.
Budget limitations led to an unconventional engine setup: the rear engine was started using compressed air, after which the front engine was engaged via a mechanical friction clutch. When both engines reached synchronization, they were locked together with a dog clutch for the record attempt. The final demonstration run at Brooklands was performed slowly on a single engine with the dog clutch disengaged.
Variants
- Cossack I
- Basic V-12 featuring cast-iron cylinder blocks, bore of , and single ignition powered by two magnetos; rated at at 2,000 rpm.
- Cossack II
- Enhanced Cossack model incorporating dual ignition and hand/compressed air starters; rated at at 2,000 rpm.
- Cossack III
- Engine designed for airship use delivering 350 hp at 2,000 rpm and weighing dry.
- Amazon
- Straight-six version of the Cossack with dual ignition and cast-iron blocks arranged in groups of three; rated at at 2,000 rpm.
- Amazon II
- Non-aviation variant with single ignition; rated at at 2,000 rpm.
- Saracen
- Increased bore size of , aluminium alloy blocks; rated at at 2,000 rpm but failed to attract orders beyond prototype stage.
- Viking
- W-18 layout using Cossack cylinder blocks intended for the AD Seaplane Type 1000 floatplane for RNAS. Production ended after nine units; surplus engines were reassigned to motorboat use.
- Matabele I
- V-12 engine with aluminium alloy blocks and bore of , featuring dual ignition with four magnetos; rated at at 2,000 rpm for aviation purposes.
- Matabele II
- Non-aviation model equipped with single ignition and compressed-air/hand starters; commonly used in motorboats.
Applications
- AD Seaplane Type 1000 (Cossack, Viking)
- Short Type 310 (Cossack)
- Porte Baby FB.2 (Cossack)
- Felixstowe F.3 (Cossack)
- Handley Page Type O/400 (Cossack)
- Tellier Flying boat (Cossack)
- HM Airship R36 (Cossack III)
- HM Airship R37 (Cossack III) – dismantled when nearly complete
- HM Airship R38 (Cossack III) – project discontinued
- Coastal class blimp C-14 (Amazon?)
- Thorneycroft Coastal motor-boats (Viking)
- Airco DH.4 (Matabele II)
- Sunbeam Despujois I–V – motorboats powered by Matabele II
- Maple Leaf VII – Sir Edward Mackay Edgar's Saunders-built motorboat from 1921 (Matabele II)
- Sunbeam 1000 hp – land speed record car powered by Matabele I
Further Reading
- The Illustrated Encyclopedia of Aircraft, Aerospace Publishing, London
- Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough: Airlife Publishing, 2003.
- Brew, Alec. Sunbeam Aero-Engines. Airlife Publishing, Shrewsbury