behind the wing, with fixed intake and exhaust ducts coupled to the outside air stream for engine operation. Since then a new generation of jets have been offered for the Schempp-Hirth Ventus 2, Jonker JS-1 Revelation and the HpH 304, all featuring sustainer jet engines. Other self-launching types include the experimental LET L-13TJ Blaník, a version of the Alisport Silent Club and a version of the TeST TST-14 Bonus. Use of engines in self-launching sailplanes The engine cannot always be relied upon to start in flight, so the pilot must allow for this possibility. The generally accepted practice is to get in position for landing at a suitable airport, or off-airport out-landing field, before extending the propeller and attempting an engine start. This allows for a safe landing in the event that the engine cannot be started in time. In soaring competitions, starting the engine is usually scored the same as an out-landing in an unpowered glider. To detect the use of the engine, GNSS Flight Recorders used in motor gliders must have a noise sensor that allows recording the sound level along with position and altitude. In many competitions, the rules require that the pilot start the engine at the beginning of the flight, before starting the task, to ensure an engine start later in the flight will be detected. Gliders without an engine are lighter and, as they do not need a safety margin for an engine-start, they can safely thermal at lower altitudes in weaker conditions. So, pilots in unpowered gliders may complete competition flights when some powered competitors cannot. Conversely, motor glider pilots can start the engine to extend a flight if conditions will no longer support soaring, while unpowered gliders will have to land out, away from the home airfield, requiring retrieval by road using the glider's trailer. The presence of an engine can increase the safety of gliding, as a powerplant increases the ability of the pilot to avoid storms and off-airport landings. An opposing view is that motor gliders are against the spirit of the sport, and, more importantly, that they sometimes give pilots a false sense of security. Touring motor gliders are seldom used in competition, but they can be useful in training for cross-country flights. After take-off, the engine is switched off, and the trainee flies the aircraft as a glider. Landings in unfamiliar fields can be practiced while the motor