Hewland AE75
{{Short description|British aircraft engine}}
{{Use dmy dates|date=March 2023}}
{{Use British English|date=March 2023}}
| {{Infobox aircraft begin
|name = Hewland AE75 aero-engine |image = |caption = }} {{Infobox Aircraft Engine |type=Piston aero engine |manufacturer= Hewland |national origin=United Kingdom |first run= |major applications= |number built = |program cost = |unit cost = |developed from = |variants with their own articles = |developed into = }} |
The Hewland AE75 is a lightweight aircraft engine that was manufactured in the mid-1980s by Hewland in Maidenhead, United Kingdom. The engine, a two-stroke inverted inline triple of {{convert|750|cc|cuin|0|abbr=on}} displacement, is liquid-cooled and yields {{convert|75|hp|kW|0|abbr=on}}“Pilot” magazine February 1986 page 32
Design and development
Image:ARV prototype.jpg with Hewland AE75 75 bhp engine]]
Th AE75 was developed from Hewland's own {{convert|500|cc|cuin|0|abbr=on}} twin-cylinder microlight engine. The engine was designed specifically for the ARV Super2, a lightweight two-seater shoulder wing aircraft. The AE75's design is compact and light at {{convert|49|kg|lb|0|abbr=on}} and yields a power-to-weight ratio of 1.14 kW/kg. Lubrication is via 40:1 pre-mix two-stroke oil.ARVSuper2 Pilot's Operating Handbook (POH) section6 page2“Pilot” magazine February 1986 page 34
Each of the engine's three cylinders has its own carburetor, with an alternate air device to provide carburetor heat. Each cylinder has twin spark plugs, the sparks being provided by a dual ignition system using engine-triggered amplifiers and coils,Super2 Maintenance manual chapter 74 page1 rather than the more common aviation magneto. The ignition circuit redundancy is such that if one circuit should fail, all three cylinders will still run. Even if two circuits fail, the engine will still fire on two out of three cylinders.Super2 Maintenance manual chapter 74 page2
The engine has a 2.7:1"Air Pictorial" magazine April 1986 Propeller Speed Reduction Unit (PSRU) with helical gears in an oil bath. Final drive to the wooden {{convert|63|in|cm|0|abbr=on}} diameter 2-blade Hoffman propeller{{Cite web|url = http://www.lightaircraftassociation.co.uk/engineering/NewMods/Aircraft_Type_Files/152%20-%20ARV%20SUPER%20TWO.pdf|title = LAA Propeller Type List PTL/1|accessdate =31 August 2011|last = Light Aircraft Association|authorlink = |date=March 2011}} was via a rubber “doughnut” coupling. The PSRU design sited the axis of the propeller below that of the crankshaft. This feature allowed a more pointed nose on the ARV, at the cost of slightly reduced propeller clearance.
The Hewland AE75 was never fitted to any aircraft apart from the ARV Super2, and when ARV production ceased, Hewland stopped AE75 production also. The rights to the AE75 were bought by MidWest, who were developing their AE100 twin-rotor Wankel aero-engine. MidWest had intended to restart production of the AE75 near Stroud, Gloucestershire, but this never materialised. MidWest based the AE100's gearbox on the AE75's PSRU, amending it so that the propeller axis was above the eccentric shaft's axis. This increased propeller clearance, but also raised the ARV's thrust line.{{Citation needed|date=August 2011}}
MidWest was bought by Diamond Aircraft Industries of Wiener Neustadt, Austria, but MidWest's rights to the Hewland AE75 engine were sold to a Manchester, UK private buyer. The new owner has made some modifications to the AE75, including increasing output from {{convert|75|to|90|hp|kW|0|abbr=on}}. Also being addressed is one of the AE75's identified deficiencies, the water-pump belt drive which, should the belt break when airborne, can lead to overheating and piston seizure.{{Cite web|url = http://www.aaib.gov.uk/publications/bulletins/november_bulletin/arv1_super_2__g_bmwe.cfm|title = ARV1 Super 2, G-BMWE|accessdate = 31 August 2011|last = Air Accidents Investigation Branch|authorlink = |date=August 2006}} Resumed production of this modified Hewland engine is uncertain.
The Hewland AE75 should not be confused with the Austro Engine AE75R,Austro Engine gmbh brochure Nov2 009 a Wankel aero-engine developed from the MidWest AE50, a single-rotor version of the AE100.
Applications
Specifications
{{pistonspecs|
|type= two stroke inverted inline triple,
|bore=
|stroke=
|displacement= {{convert|750|cc|cuin|0|abbr=on}}
|length=
|diameter=
|width=
|height=
|weight= {{convert|49|kg|lb|0|abbr=on}}
|valvetrain= none (two-stroke piston ports)
|supercharger=
|turbocharger=
|fuelsystem=three carburetors, one for each cylinder, with carb heat
|fueltype=Avgas 100/130 or Auto Gas 91 Octane Minimum
|oilsystem=two-stroke pre-mix
|coolingsystem=Liquid cooled
|power={{convert|75|hp|kW|0|abbr=on}} at 6750 rpm
|specpower=
|compression=
|fuelcon=14 litres/h at 75% power
|specfuelcon=
|oilcon=
|power/weight=1.14 kW/kg
}}
See also
{{aircontent
|see also=
|related=
|similar aircraft=
|lists=
|similar engines=
}}
References
{{reflist}}