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Japan Aerospace Exploration Agency

Long-endurance UAS technology


March 25, 2015

Operating tests on a high-altitude, turbocharged engine for a high-altitude, long-endurance aircraft performed

Equipment for testing highaltitude, turbocharged engines using a reciprocating engine

In March 2015, JAXA performed operating tests on a high-altitude, turbocharged engine at its Chofu Aerospace Center.

While the most common type of aircraft engine is the gas turbine type, with its compact size and high levels of output, JAXA is exploring the idea of using reciprocating engines (diesel engines) in unmanned aircraft with long-endurance capabilities. Reciprocating engines may be heavier than their gas turbine counterparts, but they also boast high levels of fuel efficiency that make it possible to reduce the amount of fuel that aircraft need to have on board for long flights.

For the recent operating tests, JAXA created a prototype for a lightaircraft reciprocating engine with a two-stage turbocharger to boost the density of the air flowing into the engine. The tests involved assessing operations in a low-air-pressure environment to simulate the thin air conditions that characterize high-altitude flight.

Using these test results and data from simulations, JAXA will verify whether the engine can produce enough output for the high-altitude, long-endurance unmanned aircraft currently under consideration for development.