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

66 Dossier | BMPower fuel cell power system BMPower specifies a number of hours of operation after which the system needs to be diagnosed by the company or an authorised agent. Based on the results of this diagnosis, the decision is made to replace the system or overhaul it and thereby extend its lifecycle. Performance Ivanenko points out that in more than 50 years of development, lithium batteries have been unable to exceed an energy density of 160 W-h/kg in real usage, whereas already a BMPower system can comfortably exceed 600. He says that, compared to a lithium battery of the same weight and dimensions, a BMPower FCPS can supply enough additional energy to extend the flight time of a multi-rotor UAV from 30 to 150 minutes. He notes that an alternative approach to increasing multi-rotor UAV flight time is to move to a hybrid system, whereby a small IC engine converts the chemical energy in gasoline into electricity by driving a generator. He also remarks that, by comparison, the fuel cell is vibration- free, more tolerant to low temperature and altitude, noiseless and free from infrared detection, lacks the friction of moving parts, is environmentally more friendly and offers an inherently longer service life. Compared to a typical multi-rotor UAV using a lithium-polymer battery, Ivanenko says switching to the BMPower FCPS extends the window for feasible starting temperatures from -5 to +40 C to -40 to +40 C. At the same time, the energy density of the propulsion system increases from less than 160 W-h/kg to potentially more than 600 W-h/kg, and the number of potential stop/start cycles before recharge increases from less than 200 to more than 1000. In operation, the BMPower FCPS is like a battery, characterised by a lack of noise and vibration, but it has a much higher energy density and arguably ‘greener’ credentials. Service life is also inherently longer, and by connecting a new gas cylinder it can be recharged in a couple of minutes. Customers looking for a further increase in flight time normally have the potential to use a larger cylinder – no other system modifications are necessary. The 1000 W BMPower 1000 system supplies voltage in the 24-56 V range, and using a 7 litre cylinder the running time is 175 minutes, increasing to 250 minutes using a 10 litre cylinder (see sidebar: BMPower FCPS specs). The system with the 7 litre cylinder has a total weight of 5.5 kg and an energy density of 534 W-h/kg, while the respective figures for the 10 litre cylinder are 6.5 kg and 646 W-h/kg. A customer can have its BMPower FCPS re-installed in another vehicle. This is possible given that the system has been designed to make it possible to reprogram and tune it to the appropriate voltage. Ivanenko notes that the FCPS is suitable for any standalone device, whether it is a multi-rotor UAV, a fixed- wing UAV, robot or any other portable device. Clearly the potential for the BMPower FCPS is enormous. This octocopter is powered by BMPower’s 1000 W FCPS. Its maximum take-off weight is 30 kg, it can carry up to 5 kg of payload and can fly for two-and-a-half hours (the same vehicle with lithium batteries manages only 50 minutes). This was presented at the Farnborough Airshow The FCPS can be re-installed in another vehicle, as it has been designed to be reprogrammed and tuned to another voltage October/November 2018 | Unmanned Systems Technology