Hewland AE75
Encyclopedia
The Hewland AE75 is a lightweight two stroke, inverted, inline triple, liquid-cooled
75 hp aircraft engine
of 750 cc displacement, that was manufactured in the mid-1980s by Hewland
in Maidenhead
, United Kingdom
.
, a lightweight two-seater shoulder wing
aircraft. The AE75's design is compact and light at 49 kg (108 lb) and yields a power-to-weight ratio of 1.14 kW/kg. Lubrication is via 40:1 pre-mix two-stroke oil.
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, rather than the more common aviation magneto. The ignition circuit redundancy is such that 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.
The engine has a 2.7:1 Propeller Speed Reduction Unit
(PSRU) with helical gears in an oil bath. Final drive to the wooden 63 in (160 cm) diameter 2-blade Hoffman propeller 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.
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 75 hp. 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. Resumed production of this modified Hewland engine is uncertain.
The Hewland AE75 should not be confused with the Austro Engine AE75R, a Wankel aero-engine developed from the MidWest AE50, a single-rotor version of the AE100.
Radiator (engine cooling)
Radiators are used for cooling internal combustion engines, mainly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plant or any similar use of such an engine....
75 hp aircraft engine
Aircraft engine
An aircraft engine is the component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines...
of 750 cc displacement, that was manufactured in the mid-1980s by Hewland
Hewland
Founded by Mike Hewland in 1957, Hewland is a British engineering company specialising in racing-car gearboxes. Hewland was the first company to manufacture a bespoke racing-car gearbox....
in Maidenhead
Maidenhead
Maidenhead is a town and unparished area within the Royal Borough of Windsor and Maidenhead, in Berkshire, England. It lies on the River Thames and is situated west of Charing Cross in London.-History:...
, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
.
Design and development
Th AE75 was developed from Hewland’s own 500 cc twin-cylinder microlight engine. The engine was designed specifically for the ARV Super2ARV Super2
The ARV Super2 is a British two-seat, strut-braced, shoulder wing, light aircraft, designed by Bruce Giddings as an affordable trainer. Around 35 aircraft were produced in the 1980s before the manufacturing companies went into liquidation....
, a lightweight two-seater shoulder wing
Shoulder wing
A shoulder wing is a monoplane aircraft wing configuration in which the wing is mounted near the top of the fuselage, but not on the top....
aircraft. The AE75's design is compact and light at 49 kg (108 lb) and yields a power-to-weight ratio of 1.14 kW/kg. Lubrication is via 40:1 pre-mix two-stroke oil.
Each of the engine’s three cylinders has its own carburetor
Carburetor
A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....
, with an alternate air device to provide carburetor heat
Carburetor heat
Carburetor, carburettor, carburator, carburettet heat is a system used in automobile and piston-powered light aircraft engines to prevent or clear carburetor icing. It consists of a moveable flap which draws hot air into the engine intake...
. Each cylinder has twin spark plugs, the sparks being provided by a dual ignition
Dual ignition
Dual Ignition is a system for spark-ignition engines, whereby each cylinder has every critical ignition component duplicated, including spark plugs, magnetos and ignition circuits, rather than the more usual single spark plug or circuit...
system using engine-triggered amplifiers and coils, rather than the more common aviation magneto. The ignition circuit redundancy is such that 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.
The engine has a 2.7:1 Propeller Speed Reduction Unit
Propeller Speed Reduction Unit
A Propeller Speed Reduction Unit is a gearbox or a belt and pulley device used to reduce the output revolutions per minute from the higher input rpm of the powerplant...
(PSRU) with helical gears in an oil bath. Final drive to the wooden 63 in (160 cm) diameter 2-blade Hoffman propeller 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
MidWest AE series
| -See also:-External links:*...
twin-rotor Wankel aero-engine. MidWest had intended to restart production of the AE75 near Stroud
Stroud
Stroud a town and civil parish in the county of Gloucestershire, England.Stroud may also refer to:*Stroud, New South Wales, Australia*Stroud, Ontario, Canada*Stroud , Gloucestershire, UK*Stroud...
, Gloucestershire
Gloucestershire
Gloucestershire is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn, and the entire Forest of Dean....
, 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.
MidWest was bought by Diamond Aircraft Industries
Diamond Aircraft Industries
Diamond Aircraft Industries is an Austrian-based manufacturer of general aviation aircraft and motor gliders, which also has a large manufacturing facility in London, Ontario, Canada...
of Wiener Neustadt
Wiener Neustadt
-Main sights:* The Late-Romanesque Dom, consecrated in 1279 and cathedral from 1469 to 1785. The choir and transept, in Gothic style, are from the 14th century. In the late 15th century 12 statues of the Apostles were added in the apse, while the bust of Cardinal Melchior Klesl is attributed to...
, Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
, but MidWest's rights to the Hewland AE75 engine were sold to a Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...
, UK private buyer. The new owner has made some modifications to the AE75, including increasing output from 75 hp. 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. Resumed production of this modified Hewland engine is uncertain.
The Hewland AE75 should not be confused with the Austro Engine AE75R, a Wankel aero-engine developed from the MidWest AE50, a single-rotor version of the AE100.