Bernard Hooper, Chief Engineer of Norton Villiers Ltd from 1965 to 1974, was responsible for the design of the Norton Commando. He led the team behind this highly successful British Motorcycle securing the future of the Norton Company at that time. Later work comprised advanced projects including the stepped piston engine for single cylinder industrial and motorcycle application (as shown below) to expand the Norton range.

The first modern multi-cylinder stepped piston engine, designed by Bernard Hooper whilst Chief Engineer of Norton Villiers Ltd. The engine was 500 cm³ capacity producing 42 BHP at 6500 RPM, achieving a mean top speed of 103.15mph at the MIRA proving grounds. Group Chairman, Dennis Poore, insisted that the basic engine should be able to allow for a 750 cm³ unit from the same engine block. This means that the 500 cm³ unit shown is of course much larger than it would otherwise be. The air cooled Wulf shown above was further developed at BHE Ltd as a liquid cooled Wulf II unit in the interests of creating a low emissions two stroke engine with greater efficiency. The Norton Wulf, Wulf II, Norton 76 (new Commando replacement) and EURO50 (50 cm³ entry level bike) are currently on loan to the National Motorcycle Museum at Solihull in England.

Details of a more recent stepped piston Motorcycle engine can be seen on the Motorcycle Engines page of this website. Development of the stepped piston engine is ongoing at Bernard Hooper Engineering Ltd for a number of applications (please select from our Home Page).

Selected Technical Papers

• Hooper, P.R. (2024) - "Hydrogen fuelled stepped piston engine for ultra-low emissions hybrid and range extender electric vehicles" (Int. J. Powertrains, Vol. 13, No. 3, pp.313–335.) https://doi.org/10.1504/IJPT.2024.142182

Link to paper

• Hooper, P.R. (2024) - "Energy recovery from landfill gas emissions using a stepped piston segregated scavenge engine" (Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy. 2024;238(4):676-689) doi:10.1177/09576509241231020

Link to paper

• Hooper, P.R. (2024) - "Low emission stepped piston engine for marine outboard motor application" (Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment. 2024;238(4):900-910). doi:10.1177/14750902231220697

Link to paper

• Hooper, P. R. (2021) - "Low noise, vibration and harshness solutions for in-line three-cylinder range extender and hybrid electric vehicles" (International Journal of Engine Research. 2021;22(2):581-591)

Link to paper

• Hooper, P. (2018) - "Novel Three-Cylinder Engine Solutions offering Low Noise Vibration and Harshness for Range-Extender and Hybrid Electric Vehicles" (SAE Technical Paper 2018-01-1553, 2018) https://doi.org/10.4271/2018-01-1553.

Link to paper

• Hooper, P. R. (2018) - "Investigation into a stepped-piston engine solution for automotive range-extender vehicles and hybrid electric vehicles to meet future green transportation objectives" (Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 232(3))

Link to paper

• Hooper, P. (2017) - "Low Volatility Fuel Cold Start Experience with a Stepped Piston UAV Engine to Address Single Fuel Objectives" (SAE International Journal of Engines 10(4):2017. SAE Technical paper 2017-01-9283, DOI: 10.4271/2017-01-9283)

Link to paper

• Hooper, P. (2016) - "Low Cost Possibilities for Automotive Range-Extender/Hybrid Electric Vehicles to achieve low CO2 and NVH Objectives" (SAE Technical Paper 2016-01-1841, 2016, doi:10.4271/2016-01-1841) http://papers.sae.org/2016-01-1841/

Link to paper

• Hooper, P. (2015) - "Experimental experience of cold starting a spark ignition UAV engine using low volatility fuel" (Journal of Aircraft Engineering and Aerospace Technology, 89(1))

• Hooper, P.R., Al-Shemmeri, T and Goodwin, M.J. (2012) - "An experimental and analytical investigation of a multi-fuel stepped piston engine" (Journal of Applied Thermal Engineering April 2012)

Link to paper

• Hooper, P.R., Al-Shemmeri, T and Goodwin, M.J. (2011) - "Advanced modern low emission two-stroke cycle engines" (Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. Vol. 225 No.11, November 2011)

Link to paper

• Hooper, P.R. (2005) - "Stepped Piston Engines for Multi-Fuel UAV Application" (IMechE Conference on Propulsion Systems for Unmanned Aircraft, Bristol, 14 April 2005) *

* - This paper was awarded the Institution of Mechanical Engineers Aerospace Industries Division Charles Sharpe Beecher Prize, "for the best paper on an aerospace subject published by the institution in the previous year or for a contribution in that field," at the AID AGM at IMechE HQ on 16 May 2006.

• Hooper, P.R. (2001) - "A Stepped Piston Engine for UAV Application" (UVS TECH 2001 Conference Brussels, November 2001)

• Hooper, P.R. (1999) - "Initial Development of a Multi-fuel Stepped Piston Engine for Unmanned Aircraft Application" (4th International Conference ICE99, Capri, Naples 12-16 September 1999)

• Hooper, B and Hooper, P.R. (1996) - "Initial Heavy Fuel Development of Stepped Piston and Crankcase Scavenged Two-cycle Engines" (12th International RPV Conference, Bristol University, 9-11 September 1996)

• Hooper, B and Hooper, P.R. (1991) - "Design and Development of the 30kW RPV Stepped Piston Engine" (9th International RPV Conference, Bristol University, 9-11 September 1991)

• Hooper, B and Favill, J.E (1978) - "Modern Stepped Piston Engines" (IMechE paper C133/78 Design and Development of Small IC Engines Conference 31 May - 2 June 1978)

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