Flying Cars: The Future of Travel?

What would it be like to walk into your garage, hop into your private flying machine, pull out into the driveway and lift off vertically to fly to your job at the post office? Sounds pretty cool, right? Well, VSTOL (Vertical Takeoff and Landing Craft) have been under development for some time. And commercial models are just around the corner.

As of now, there are some prototypes that work, but the main issue remains the low energy density of batteries which prevent us from using the VSTOL for extended periods of time. For the past few years the most regularly used batteries have been lithium-ion ones which only allow crafts to fly for about twenty minutes without having to stop and recharge them. These are currently used in Tesla cars for example. Batteries are getting better every year though, and so, our flight time is getting longer. We can now theoretically fly for about an hour. The main reason for the improvement of these batteries, is the increased energy density that the batteries hold. The developments are so fast that Lilium, a German aviation startup, claims there will be flying taxis by the year 2020! 

This new solid-state battery will easily outperform the presently used lithium-ion one. It will be able to hold 2.5 times more energy, will be smaller and will recharge faster than the lithium-ion battery. The reason for this improvement, is the fact that the electrical current that flows between the anode and cathode in the battery, will pass through a solid electrolyte instead of a liquid one. This is illustrated in Figure 1. Another huge advantage that this solid state battery has, is that the solvent used to make the battery is the cheapest you can get: water. This development will also extend to normal cars. Not only will flying cars, as well as normal cars, travel faster and have a longer range, but they will also be cheaper. This is hard to believe, but it’s already happening.

The most common VSTOL model (see image) uses a quadcopter mechanism to fly. I know that most of you were expecting these flying cars to be like UFO’s and use some cool physics involving the creation of plasma from air which would then make it hover with the help of an electric current and repulsion between charges. Unfortunately, this vision still has yet to materialise and is unlikely to do so in the years to come.

The quadcopter has four motors, each attached to a propeller and positioned at each of  the four corners of the VSTOL. A very similar mechanism is used with drones. To hover, the motors all rotate at the same speed, but not all in the same direction. Each motor spins in the opposite direction than its immediate neighbours. This is to prevent rotation about its vertical axis. If all the rotors spin in one direction, the craft then spins in the opposite one. To turn to the right, the two motors on the left will be turned up so that they will spin faster than the ones on the opposite side, making the craft tilt to the right. Lastly, to pitch down, the two back motors have to spin faster than the two front ones. This tilt is what we need to make the craft move forward.