Editing Motor glider (section)

==Categories==
Most motor gliders are equipped with a [[Propeller (aircraft)|propeller]], which may be fixed, feathered (e.g. [[AMS-Flight Carat]]), or retractable. However jet engine-powered motorgliders are now available from some manufacturers, some of which are intended for use only as "sustainer" engines, i.e. for sustaining gliding flight rather than as self-launching aircraft.

===Sustainer motor gliders===
Sustainer motor gliders must be launched like an unpowered glider, but can climb slowly to extend a flight once the engine is deployed and started. They generally do not have an [[alternator]] or [[starter motor]], so the engine is started by "wind-milling" the propeller in flight. The propeller may be a rigid 2-blade design, or may have more than two blades that fold at the hub when the engine is retracted.  The propeller hub is usually attached directly to the crankshaft, but there is at least one example of a sustainer with a belt reduction drive, the DG-1000T.<ref>{{cite web|url=http://www.dg-flugzeugbau.de/index-e.html|publisher=DG Flugzeugbau|title=DG-1000T Information|access-date=24 November 2006|url-status=dead|archive-url=https://web.archive.org/web/20061205063859/http://dg-flugzeugbau.de/index-e.html|archive-date=5 December 2006}}</ref>

The smaller sustainer engines are usually not equipped with a throttle, but instead have a cable to open decompression valves in each cylinder to allow the engine to turn freely for starting. Sustainer engines are typically [[two-stroke]] two-cylinder [[air-cooled engine]]s in the range of 18–30&nbsp;hp (14–22&nbsp;kW). They are lighter in weight, and simpler to operate than self-launching powerplants.<ref>{{cite web|url=http://www.schempp-hirth.com/index.php?id=discus-2t&L=1|publisher=Schempp-Hirth|title=Discus 2T Sustainer Engine Information|access-date=24 November 2006|url-status=dead|archive-url=https://web.archive.org/web/20061016161425/http://www.schempp-hirth.com/index.php?id=discus-2t&L=1|archive-date=16 October 2006}}</ref>

===Self-launching motor gliders===
[[File:WankelPP.jpg|thumb|Powerplant from a [[Schleicher ASH 26]]E self-launching motor glider, mounted on a test stand for maintenance at [[Alexander Schleicher GmbH & Co|Alexander Schleicher]] in [[Poppenhausen, Hesse|Poppenhausen]], Germany. Counter-clockwise from top left: propeller hub, mast with belt guide, radiator, Wankel engine, muffler shroud.]]
Self-launching retractable propeller motor gliders have sufficient thrust and initial climb rate to take off without assistance, or they may be launched as with a conventional glider. The engines also have a starter motor and a large battery to allow the engine to be started on the ground, and an alternator to recharge the battery. A two-blade propeller is typically coupled to the engine via a belt [[reduction drive]]. In older designs, the propeller alignment must be checked by the pilot using a mirror, before it is retracted into the fuselage; however in current production gliders, propeller alignment is fully automatic.

Another solution is the [[single-blade propeller]] that offers the advantage of a smaller opening in the fuselage to retract the engine.

Internal combustion engines can benefit from mounting in the fuselage, rather than on the propeller mast. This allows them to be connected to a larger muffler for reduced noise when operating, something which is mostly relevant to European operation. It also allows the belt tension to be relieved when the engine is retracted to extend the life of the belt and bearings. The drawback of this arrangement is that engines fixed low in fuselages are more difficult to pre-flight and service, and highly stressed power transmission belts should not be bent or twisted.

Self-launching engines are equipped with a throttle that allows the engine power to be adjusted for ground operations.  Self-launching engines are typically in the range of 50–60&nbsp;hp (38–45&nbsp;kW).  The higher engine output power requires liquid cooling with a separate radiator mounted on the propeller mast.  Engines commonly used are [[Two-stroke engine|two-stroke piston engines]], or [[Wankel rotary engine]]s.<ref>{{cite web|url= http://www.alexander-schleicher.de/englisch/produkte/ash26/e_ash26_main.htm |title= Alexander Schleicher GmbH & Co., ASH 26 E Information|access-date=24 November 2006|archive-url= https://web.archive.org/web/20061008125929/http://www.alexander-schleicher.de/englisch/produkte/ash26/e_ash26_main.htm |archive-date= 8 October 2006}}</ref>

===Touring motor gliders===
<!-- This section is linked from [[Gliding]] -->
Motor with fixed or full feathering propellers are generally classified as Touring Motor Gliders (TMGs). TMGs can take off and cruise like an [[airplane]] or soar with power off, like a [[Glider aircraft|glider]].

They are fitted with front-mounted engines, similar to a small airplane.  The large [[wingspan]]s of TMGs provide a moderate [[gliding]] performance, not as good as that of unpowered gliders. However TMGs are more efficient than conventional [[light aircraft]].

Most TMGs are designed with engines of 80 to {{convert|100|hp|abbr=on}} and typically cruise (under power) at 85–{{convert|100|kn|km/h}}. Most have fuel tanks capable of holding between 50 and 100 liters (13 to 26 US gallons) of fuel, giving a range under power of up to 450 nautical miles (approximately 830 kilometers). Modern TMGs like the [[Phoenix Air Phoenix]] are capable of higher speeds and longer range under power.

Some TMGs are equipped with folding wings to allow them to fit in standard small airplane [[T-hangar]]s. Tow hooks are unnecessary, since aircraft with self-launch ability do not require access to winch or tow plane for [[Gliding#Launch methods|launching]] like a conventional glider.

Some TMGs, like the [[Europa Aircraft|Europa]] or the Phoenix, can also be supplied with interchangeable wings or wingtips so that they can be flown as a standard touring aircraft as well as a TMG.<ref>{{Citation | url = http://www.europa-aircraft.com/ | title = Europa Aircraft | type = homepage}}.</ref>

[[File:grob.g109b.glider.arp.jpg|thumb|[[Grob G 109]]B touring motor glider, with [[fibre-reinforced plastic]] construction.]]
[[File:Motorseglare - SF25 Motorfalke - Ystad-2020.jpg|thumb|Motor glider ''SF25 Motorfalke'' over [[Ystad]] 2020.]]
The [[landing gear]] configuration on TMGs usually incorporates two fixed main wheels, allowing it to be [[taxiing|taxied]] on the ground without a wing walker. While some TMGs have only one main wheel, with auxiliary trolley wheels on the wings for taxiing, it is becoming more common to find them being manufactured with tricycle and conventional (two fixed main wheels – i.e. a "tail-dragger") landing gear configurations.

Since the additional [[drag (physics)|drag]] of the stopped propeller and landing gear reduces their gliding performance, TMGs are seldom used in competition.