Doing Extremely Intensive Research and Searching for Valiant Solutions with Modified SWOT and PESTEL Frameworks
We’ve been going through different options for a power plant and construction materials. A propeller driven by an electric motor would be an ideal choice in terms of efficiency environmental protection, as it is quiet and doesn’t produce any pollution. However, limitations in battery technology form a hurdle that may not be easily surpassed. Batteries have a relatively low energy density compared to other conventional sources of energy (250 Wh/kg in lithium ion battery vs. 13 kWh/kg in diesel/gasoline). This means that the total mass of the batteries will be heavier than the fuel mass for an internal combustion engine, when all other factors are equal.
Another suitable source for electric energy could be a hydrogen fuel cell. US Naval Research Laboratory has managed to fly their conventional fixed wing drone for 26 hours using gaseous hydrogen as a source of energy for their 550 W fuel cell. Using liquid hydrogen, they managed to extend the flight time to 48 h. https://www.nrl.navy.mil/lasr/content/ion-tiger-fuel-cell-powered-uav
There is an interesting article (http://www.compositesworld.com/articles/sparrowhawk-all-carbon-composite-sailplane) about a glider plane which is made of carbon composite. The plane weighs 70 kg which is a remarkable achievement. Usually sailplanes weigh around 200-300 kg. Carbon composite might therefore be a suitable option for our VTOL drone because we are trying to stay below the 70 kg weight limit.