- freely available
Aerospace 2019, 6(2), 20; https://doi.org/10.3390/aerospace6020020
1.1. Future Challenges
- Reduce CO2 and NOx emissions
- Reduce noise emission
- Taxi emission free
1.2. Accelerate Technology Readiness
2. Technology Test Bed e-Genius-Mod
2.1.1. Scaling Factor
- Flight conditions and test area
- Handling and transportability
- Environmental influences
- Payload test equipment
- Scalability of new technologies which shall be investigated
2.1.2. Airfoil Scaling
- Thickness / chord ratio
- Airfoil camber
- Location of maximum thickness
- Location of maximum chamber
- Leading edge radius
2.1.3. Variable Pitch Propeller
- The fixed propeller can efficiently cover a large portion of the flight envelope. In cruise flight (best range or best endurance), the fixed propeller works very close to its optimum, and the VPP barely gives any performance improvement (less than 2%). This is due to the e-Genius being a 33.3% scaled model, and having a smaller flight envelope than that of a full-scale aircraft.
- During climbing flight, the VPP improves performance by approximately 25%. However, the e-Genius-Mod, being a UAS, will mostly fly at low altitude (<500m). Consequently, climbing will be very short when compared to the cruise flight, thus limiting the performance improvement.
- The electric engine has a very good efficiency over a wide range of RPM, therefore the advantage of running the engine near its point of best efficiency (the way it would be done on a piston-engine aircraft) does not translate to the e-Genius model.
- The pitch variation system itself weighs 400 g, and due to its position at the aft of the fuselage this weight needs to be counterbalanced in the nose to keep a neutral center of gravity. Consequently, the overall weight penalty ranges from 400 to 1200 g (depending if the payload itself can be used as ballast to counterbalance this without adding overall weight, but this may not always be possible). Therefore, in most flight situations the increased weight of the variable-pitch propeller might negate the possible performance improvements.
- If the runway is particularly short, take-off performance can be noticeably improved.
- If the flight tasks require flying at either very low or very high speeds, outside the range where the fixed propeller performs well.
3.1. Flexible Airframe Configuration
3.2. Systems Design
3.3. Free–Flight Model e-Genius Mod
- Inertial measurement unit—data of flight attitude (angle of orientation, acceleration, rotation rate)
- Air data boom—angle of attack, side slip, static and dynamic pressure
- GPS—position of the aircraft
- Actuator feedback—control surface angle
- Monitoring sensors—battery current/voltage/temperature, engine RPM/temperature
3.4. Application Example—Investigation of a Wing Tip Propulsion System
Conflicts of Interest
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|Profil Parameter||Original Full-Scale Airfoil||Modified Scale Airfoil|
|Thickness/chord ratio (%)||17.01||14.00|
|Airfoil camber (%)||2.71||2.62|
|Location of maximum thickness (%)||40.40||39.39|
|Location of maximum camber (%)||39.39||38.38|
|Leading-edge radius (m)||0.02026||0.01383|
|Electric drive power||5 kw|
|Payload||up to 10 kg|
|Design speed||24.8 m/s|
|Max. speed||35.6 m/s|
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