Certification jet engine TJ-42

The demand for small jet engines to be utilized in gliders and motor gliders increases steadily. The engines are adventageous in various situations, wether to bridge the distance between two thermals or to ensure a safe return to the airfield. The turbines themselves are usually based on ones from the field of model building, but these are often not powerful enough.

For this reason, M&D Flugzeugbau GmbH & Co. KG has decided to qualify as an EASA- approved manufacturer and to develop their own engine from scratch.

The resulting retractable engine TJ-42 has received EASA certification after a long-term licensing process. It took a total of six years to acquire the EASA Type Certificate ( TC ) since its application in September 2009. The approval for the engine took place in accordance with CS-22 ( Subpart H - Engines ). Thereby the engine simultaneously received additional approval for LSA, VLA, UL, and experimental aircraft, which means it can be considered for numerous aircraft types.

The M&D team was actively supported by aerospace engineer Stefan Hilbenz from Kasaero GmbH when creating the necessary, extensive documentation during the approval process. Within this process, the engine has been checked thoroughly at about 180 test flights of M&D test pilot Sören Pedersen and his colleagues. Besides the classic LS, the engine was also incorporated into the new JS1 and extensively tested. In collaboration with Jonker Sailplanes the engine could also be tested in the climate of South Africa.

The engine is designed to be used in gliders as a so-called "return assistant" and thus improve the flying experience of the pilot.

Therefore the 390 mm long and 150 mm wide engine provides a maximum thrust of 420 N. The engine itself weighs just over 3 kg. The entire propulsion system, including the tank, and electronic display in the cockpit, weighs only about 15 kg.Besides Jet A1, the engine can also be operated with conventional diesel fuel. With a maximum of 40 l of fuel an additional range of more than 200 km can be achieved. It only takes 40 seconds to go from startup of the engine through the extension up to full thrust.

An overview of the technical data can be seen in the following table:

Technical data

Standschub380N (max. 420N)
Drehzahl25.000 – 98000 U/min
Spez. Kraftstoffverbrauch1.3 l/min
KraftstoffDiesel/ Jet A1

Arithmetical performance data LS4

vr220 km/h (bei 80% Triebwerksleistung)
Steigen2,0 m/s
Reichweite320km (im Sägezahlstil)
Masse des gesamten Antriebssystems (ohne Kaftstoff)ca. 15kg
Flächenbelastung (vollbetankt)ca 39 – 40 kg/m²

All images courtesy of M&D Flugzeugbau GmbH & Co. KG.