Gas-powered drones solve the biggest weakness of electric drones
Electric drones are clean, convenient, lightweight, and have found seemingly endless commercial and personal uses, but even the best of them can't fly for more than 45 minutes before needing a recharge. So why not use a gasoline engine instead?
In this section:
Electric drones lack energy density
Lithium-ion batteries are the most energy dense commercial batteries available. Thanks to their ability to store energy in a small space, we have laptops, smartphones and other devices that can last for hours, or even days in some cases, while still delivering high levels of performance. Electric car ranges have also grown steadily to the point where they are practical for almost any day-to-day use.
However, lithium-ion batteries have an energy density 100 times lower than gasoline! So, instead of having enough power for 30 minutes of flight, you would have enough energy for 50 hours of flight! This doesn't take into account the added weight of the engine, but even then you're looking at a massive increase in flight endurance.
Gas-powered drones in the real world
Most gas-powered drones are still ultimately electric; it's just that the electric power comes from a gasoline engine. There are drones that use standard gasoline, and then there are drones that use "nitro", which is a methanol-based fuel that is common in the world of RC planes, cars, and helicopters. . Either way, the energy is stored as liquid fuel and then converted into electrical energy to drive the drone's rotors.
There are gasoline-powered drones that drive their rotors directly from their motor, using a complex drive system. The Nitro Stingray 500 works this way, and it's also unique in that it's a 'collective pitch' drone, with each rotor capable of independent pitch adjustment. Most multirotor drones have fixed-pitch rotors.
The Stingray can perform complex "3D" flight maneuvers with a combination of powerful thrust and this collective pitch control solution.
Then we have the Hybrid Drone, which set a world flight record of 10h14m.
The drone you can buy can operate for up to four hours, with a maximum takeoff weight (MTOW) of 25 kg (about 55 lbs). With drones like these, you can refuel them in minutes, fly for hours, and accomplish missions that are simply impossible with battery-powered drones.
Gas-powered drones have their own issues
There's a reason we don't just use gasoline to power our drones. Internal combustion engines require heaps of maintenance; they're dirty, complex, expensive, and far more likely to fail than an all-electric drone. This makes them less than ideal as consumer products. A battery-powered drone is more like a smartphone than an RC plane, and most users don't need more than the typical 30-minute flight times of modern drones.
Fuel cell drones could be the best of both worlds
Hydrogen fuel cell drones can be a good middle ground between gasoline drones and battery drones. Hydrogen has three times the energy density of gasoline and can be converted into electricity using a fuel cell without the complexity of an internal combustion engine. Fuel cells have no polluting exhaust, can be refueled as easily as gasoline, and provide hours of flight while being lighter than a gasoline system. The big downside is that fuel cell technology is expensive, while gasoline power is well understood and relatively cheap.
The first commercial fuel cell drone most closely resembled the Hydrone 1800, released in 2016. Hydrogen fuel cell drones may have a bright future, and companies such as Doosan and Intelligent Energy are making fuel cells specifically for drones. Fuel cell laptops may never have taken off with the public, but we can see drones powered by this technology gaining a foothold in various industries.
Next-gen batteries are coming
The development of battery-powered drones has barely stopped during all this research into alternative energy in the drone market. Flight times are steadily climbing towards that magical one-hour mark for consumer drones. More efficient motors and better software are part of why this is happening, but battery technology is also improving.
Graphene batteries are now available to regular consumers. You can buy graphene-infused power banks that charge much faster, have higher capacities, and don't wear out as quickly. One day we will probably have advanced solid-state batteries or supercapacitors that charge in seconds, hold much more power, and virtually never wear out.
In early 2021, the first commercially available graphene drone battery was announced. Offering 600Wh in a 22lb package, with zero fire risk and a massive increase in operating temperature range over lithium-ion batteries, it's an exciting taste of things to come.
