Would it be feasible to replace the brakes on airplanes with electric motor/generator drive systems?
There are two problems I see with airplanes. When they land, the tires are not spinning to match the ground speed, as the craft touches the ground. So there is a sudden lurch as the tires touch the ground and suddenly begin spinning. The bigger the craft, the more tire mass that must be instantly accelerated.
This disrupts flight stability, and the jolt could be enough to cause a crash or mishap in poor landing conditions. It also causes unnecessary wear and stress to the tires due to the motionless rubber dragging across the runway pavement at first contact.
It would be best for the tires to be spun up to match the ground speed before the craft touches the ground, for the smoothest landing possible.
The second part is just simply the problem of dissipation of heat. It has been discussed elsewhere here that the heat from braking can cause fires and crashes.
As in train locomotives, with a braking motor/generator, the heat could potentially be moved elsewhere to resistive heat coils covering a large area, and cooled using forward thrust or fans.
With a motor/generator unit, the tires can be spun up to either near or matching ground speed, using them as motors powered by the APU, and then switched to be used as generators for braking after ground contact is made.
Has this ever been researched or used on airplanes?
(As a lower middle-class American that is not involved in the airplane industry, I have no hope of doing anything with this or profiting from it, even if it is a practical and potentially patentable new concept that has never been tried before.)
I am not talking about regenerative braking or energy recovery into a storage battery. Someone has inferred that though I didn't say anything about it at all.
I understand the storage battery would likely be too much extra weight for a plane to carry, vs the energy recovery of takeoff and landing. (Heh, have a 2000 ft breakaway extension cord on a reel, to drive it down the runway and disconnect right before it lifts off the ground.)
I am only looking at resistive / dynamic braking, dumping the heat in huge resistor banks with a high speed blower, the same as is used on train locomotives. On a plane, air bleed from the engines can blow across the the resistor banks.
Probably should pluralize the title. Rather than a single huge motor/generator, each brake assembly would be replaced by a separate one of these.
So a large plane with say 20 wheels would have 20 motor/generator units, these running at high voltage to keep the amps and wire diameter small. This reduces weight and engineering complexity, eliminating gears and shafts linking all wheels on one set of gear, to one huge motor/gen unit.
This is not two separate devices, but one device that does both functions. Most (but not all) generic electric motors without electronic drive systems can also be a generator.
This could use a permanent magnet motor, or with a powered field coil. Neodymium is capable of extremely high flux density, but loses it when exposed to high heat, so there are density / temperature tradeoffs of permanent vs powered field coils.
Tire hub could potentially be integrated as part of the motor/gen rotor/casing for weight savings (which is very important in aircraft), using a fixed core and a hub that rotates around it in reverse of conventional motor design.