Jonker Sailplanes have selected the M&D Flugzeugbau TJ42 jet turbine engine. M&D Flugzeugbau are a German company based in Friedeburg, Lower Saxony in north-western Germany. M&D Flugzeugbau manufacture the Samburo motorglider and also provide maintenance services for other light aircraft.

In 2007 M&D identified the potential benefits of installing a small jet turbine sustainer in gliders but considered the range of jet turbines available for model aircraft had limitations. Such engines had not been designed from the outset to consider certification or in-flight starting. M&D decided that rather than convert a model aircraft jet turbine into a glider sustainer, it would be better to develop and certificate a new engine.

The key features of the TJ42 engine are:

  • Single spool jet turbine

  • Two stage axial-centrifugal stator-less compressor with a compression ratio of 1:3.8

  • Cannular combustor with multiple fuel injectors and combustion zones contained within a single annulus casing

  • Glow-plug ignition system (used in start-up sequence only, ignites top combustion zone only)

  • Single stage axial turbine with stators

  • Convergent nozzle

  • Front-mounted, direct drive electric starter motor for initial spool up

The maximum thrust is nominally 42 kgf at 100,000 rpm with an estimated fuel consumption of 66.4kg/hr at full thrust. At the idle speed of 30,000 rpm the thrust is less than 2 kgf. The weight is 3.3kg and overall dimensions 400 mm long and 150 mm diameter.

The TJ42 has a kerosene start-up (as opposed to gas start engines) which eliminates the need for separate gas canisters and long complex start-up procedures.

The start-up sequence is:

  • Glow-plug heats up for 10 seconds

  • Electric starter motor spools up engine to 8,000 rpm

  • Starter fuel solenoid pulses with fuel being injected into the top combustion zone only

  • Fuel ignited in top combustion zone by glow-plug

  • Engine spools up to 15,000 rpm

  • Normal fuel solenoid pulses with fuel being injected into all combustion zones (starter fuel solenoid closes)

  • Engine spools up to idle speed of 30,000 rpm

  • Fuel rate controlled by throttle, and matched to density altitude and rpm by ECU

The shut-down sequence is:

  • Fuel cut off and combustion ceases

  • With no fuel, the engine speed decreases and EGT decreases

  • The ECU senses EGT and rpm, and if the engine speed is too low to promote rapid cooling, the electric starter motor runs an automatic cooling cycle (spooling the engine up to 3,000 rpm, then switching off)

  • Once the EGT has dropped below 50°C the ECU signals that the engine can be retracted

The engine and pylon are enclosed by cowlings manufactured from fiberglass and aluminum (or possibly stainless steel subject to clarification of certification requirements).

Jet Turbine Sustainer System Option

  • M&D TJ42 jet turbine generating 40 kgf at maximum speed of 98,000 rpm

  • Fuel: Jet A1 or diesel fuel with added lubrication oil

  • Fully automated computer controlled system operated by a single switch and digital RPM throttle control

  • Single 57mm colour Jet Display and Control Unit for system and throttle control, displaying RPM, EGT, Fuel level and flow and battery voltage and capacity.

  • Engine and mechanical systems mounted in monocoque carbon-fibre box, easily removable for maintainability

  • Three fuselage mounted fuel tanks with integral fuel quantity sensors and filters, useable capacity of 42 litres, with fuel filler in engine box for external refuelling

  • Engine extension and retraction using an electrical linear actuator with mechanical sequencing to close engine bay doors in extended and retracted position

  • Staged pricing of the jet sustainer is available to allow the complete electromechanical and fuel system to be installed during aircraft manufacture and later installation of the jet engine

  • 12V LiFePo 10Ah main battery with circuit breaker box and duel supply connectors replacing one Avionic Lead Acid battery

  • Nose ballast system with lead plates





This website designed and maintained by GSD Potch - The WEB people...  -


We recommend that you view this website with: MS IE 7+ or Google Chrome 1.0 or  Mozilla 4.0