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Test Approach


On a specifically designed carousel the classical jet engines (FANJET) are compared against the new generation of jet engines (ZETJET) in regard to power efficiency. For this purpose we use the same off the shelve engine based on an electric impeller.


14 m diameter

44 m circumference

Short arm of 3 m with counter weight of up to 40 kg

Long arm of 7 m with engines up to 10 kg weight

Thrust experiments with electric impeller up to a power consumption of 10 kW

Air drag experiments with drive motor up to a power consumption of 7 kW

Speed up to 200 km/h

Acceleration up to 50 g



FANJET – Engine is placed outside of body


- Static air from the front

- Fast jet towards the back

- Primary thrust from momentum difference

- Nacelle is not part of the body

- Air plane receives "net" thrust (gross thrust - air drag of nacelle)

ZETJET – Engine is integrated in the body


- Static air from the side

- Fast jet towards the back

- Primary thrust from air jet

- Secondary thrust from aerodynamic profiles

- Displacement (nose) is part of body

- Air plane receives “gross” thrust

- Air plane receives additional thrust



FANJETs need to propel their own nacelle through the air. This requires thrust. The remaining net thrust is available for the airplane.

ZETJETs are placed in the slipstream, e.g. behind the body. The airplane now receives the complete gross thrust. The inflowing air from the side (secondary air flow) generates an additional thrust when passing the aerodynamic profiles.

The experiment compares the two engine concepts. Both contain the very same electric impeller. The FANJET has a nacelle exposed to the airstream while the ZETJET is integral part of the
fuselage with no additional drag.

The model engines power the carousel. The drag of the carousel represents the aerodynamic load of an aircraft. We measure the final speed at a given power input. At the same power, the more efficient engine is faster.


Website updated: April 2017