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Climb and descent
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
It is noticed that the speed for maximum climb rate is strongly dependent on the engine thrust that for a given throttle setting decreases with altitude. To increase the ROCmax (through VROCmax), one must increase the engine thrust. This speed is also a function of the altitude (ρ) and the wing area, zero-lift drag coefficient, and the maximum lift–drag ratio.
A hybrid-electric propulsion system for an unmanned aerial vehicle based on proton exchange membrane fuel cell, battery, and electric motor
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Amir Hamzeh Farajollahi, Mohsen Rostami, Mohammad Marefati
To evaluate the performance of the UAV the take-off and mission altitudes have been selected at 1500 and 300 m, respectively. However, different UAVs can be operating at different take-off and mission altitudes. Therefore, the electrical power required at different take-off and mission altitudes has been calculated here. Figure 5a illustrates the electrical power required for different flight modes as a function of take-off altitude (at a constant mission altitude of 300 m). As the take-off altitude increases, the electrical power required in climb, actual endurance and stall modes increases, but in cruise and maximum speed modes decrease. The same trend was observed with increasing mission altitude (at a constant take-off altitude of 1500 m) (see Figure 5b). However, it cannot be said with certainty that the operating altitude is an effective parameter in the performance of the UAV, and only the UAV required power in various flight modes with different operating altitudes can be calculated; because UAV’s operation is affected by various parameters. A drone with more power required may have safer performance and more important missions.