A Practical Flying Car
The idea of a flying car is not so far-fetched. Considering the advances that have recently been made in developing lightweight materials, such as carbon-fiber composites, a flying car that an ordinary person can drive is entirely possible. My own concept for a flying car is a car with a set of rotor blades that unfold. Four sets of rotor blades could be folded up inside the roof of the vehicle, and when the vehicle is in road mode, you wouldn't see these rotors. In road mode, the car would look like an ordinary car. To switch to flight mode, you must first stop the car, and extend the rotor blades. All four rotor blades would extend from the roof, and when they are fully extended, the rotor blades begin to spin, like the rotors on a helicopter. When the rotors are spinning sufficiently fast, the car would rise into the air and fly.
The illustration above shows the basic drive system for the car. The engine is an ordinary piston engine, that burns gasoline as fuel. The engine would be mounted in the center of the vehicle, for better weight distribution. If the engine were front-mounted, the front of the vehicle would be too heavy, and if the engine was rear-mounted, the rear end of the vehicle would be too heavy. A centrally mounted engine provides the best balance, for better stability, while flying. The engine would be covered with an engine cover that would include a few seats for passengers to sit on. The engine cover (and other interior components) would be made of carbon-fiber composite materials. There may be enough room for two passengers to sit on the engine cover, and an additional two passengers would sit at the front of the vehicle.
The engine would be connected to an electrical generator, by a shaft. The shaft would be made of a carbon-fiber composite material, to save weight. The generator would provide electricity to a set of electric motors, there would be one electric motor in each of the wheels. This type of electric drive system would weigh less than a drive system that has a heavy mechanical transmission.
The illustration above shows the electrical drive system for the rotors. Each of the four rotors has it's own electric motor to drive it. The electric motors that power the rotors receive electric power from the generator that is connected to the car's engine. During the flight mode, the rotors vary in speed to change the flight angle. To fly forward, the two rotors in the rear spin slightly faster than the rotors in the front, so the entire vehicle tilts forward, and flies forward. To slow down, the two rotors in the front spin slightly faster than the two rotors in the back.
To make a left turn, the two rotors on the right side of the vehicle spin slightly faster than the rotors on the left side, so the vehicle turns to the left, vice versa for a right turn. With this type of variable-speed rotor system, the flying car would not need heavy and expensive variable-pitch rotors systems like the ones used on helicopters. The variable-speed rotor system I've described here is like the system used on small drones that carry cameras.