Unmanned Systems Technology 022 | XOcean XO-450 l Radar systems l Space vehicles insight l Small Robot l BMPower FCPS l Prismatic HALE UAV l InterDrone 2018 show report l UpVision l Navigation systems

65 BMPower fuel cell power system | Dossier substitute the ICE that powers its single- engine fixed-wing UAVs to reduce noise and improve stability of operation in sub- zero temperatures. Successful flight trails have already been run. In addition, the BMPower FCPS is being considered as a replacement for the diesel generator in a portable military radar application, in particular to reduce the possibility of infrared and noise detection. Ivanenko says the FCPS would also significantly decrease the weight of the unit and increase runtime. Operation The output voltage of the BMPower FCPS depends on the connected buffer battery. This can be replaced with another one of different capacity and voltage, from a list recommended by BMPower or one produced by it. The control system will be automatically re-adjusted on initial use. To start the system, the valve controlling discharge from the hydrogen cylinder is opened, then the buffer battery is connected to the control system. Thirty seconds later the FCPS can be activated; the warm-up period is less than a minute. If the system runs out of hydrogen or otherwise fails during operation, the buffer battery will assume the role of power supply to the UAV. That supply should be sufficient for the operator, having been alerted to the condition via the data sent to the ground control station, to land the UAV safely. The noise level of the system is no more than 55 dB at maximum power, measured 1 m away. The temperature of the system’s exhaust gases (which is humid warm air) is about 45 C. It is practically impossible to detect thermal radiation at that level, particularly as the warm air immediately mixes with the surrounding air, becoming the same temperature. The membrane doping technology allows the cells to work at temperatures down to -40 C. The system is also suitable for use in high-humidity environments. It can be operated in all weather conditions, regardless of rain, snow or even dust, provided its location within the UAV protects it from direct atmospheric precipitation. An air filter protects against the danger of coarse dust (particles with a diameter of 0.5 mm or more) entering the system. Changing the filter at appropriate intervals will avoid failure of the system. However, notes Ivanenko, care must be taken when operating the system in a heavily polluted environment. Fine dust and soot contained in smoky air can clog the pores of open gas diffusion layers, in view of which the frequency of service must be increased. Carbon monoxide, nitrogen oxides and ammonia vapours – all of which may be present in smoky air – will not have a major impact on the system’s operation. Sulphur and its oxides can cause a decrease in the system’s capacity, in view of which again it is recommended that the frequency of service intervals be increased. The customer is advised to carry out routine maintenance every two months or every 200 hours of operation. No special tools are required for this. The 1000 system is so called as it is rated at an output of 1000 W. The rated supply voltage can then be in the 24-56 V range. Using a 7 litre cylinder the runtime is 175 minutes, increasing to 250 minutes using a 10 litre cylinder. The latter weighs 3.3 kg compared to 2.3 kg for the smaller cylinder (including hydrogen). The 1000 system unit itself weighs 2.2 kg while the associated fuel processing system weighs 0.4 kg and the control module and wiring 0.5 kg. The total weight using a 7 litre cylinder is thus 5.5 kg; using a 10 litre cylinder it is 6.5 kg. The respective energy densities are 534 and 646 W-h/kg. The 500 W-rated 500 system halves unit weight to 1.1 kg, with the same associated component weights plus the 7 litre cylinder with which it is compatible. Its voltage output is rated at 10-30 V and its runtime is 335 minutes. With its total weight of 4.2 kg its energy density is 694 W-h/kg. Doubling up the 1000 to produce the 2000 W-rated 2000 system halves the runtime to 125 minutes using the same 10 litre cylinder, shared between the dual units. This approach doubles the fuel module’s weight and increases the fuel processing system’s weight to 0.6 kg, and control module and wiring weight to 0.7 kg. The upshot is a total system weight of 9.0 kg and an energy density of 464 W-h/kg. Adding a third module allows the use of a (single) 25 litre, 7.3 kg cylinder, which for the 3000 W system provides a runtime of 210 minutes. The voltage output is again in the 24-56 V range. Tripling fuel module weight, the 3000’s fuel processing system weight is 0.7 kg while its control module and wiring weight is 0.9 kg. The upshot is a total system weight of 15.5 kg and an energy density of 678 W-h/kg. The standard module measures 235 x 220 x 124 mm while the 500 ‘half’ module measures 225 x 145 x 124 mm. The control module used by all current systems measures 70 x 55 x 30 mm. The 7 litre cylinder (including regulator) has a diameter of 148 mm and a length of 600 mm. The respective 10 litre cylinder dimensions are 185 and 635 mm; the respective 25 litre cylinder dimensions are 380 and 480 mm. BMPower FCPS specs Unmanned Systems Technology | October/November 2018