Viability of Magnetically started engines I am working on a school project of mine which involved testing the viability of a magnetically started jet engine. By magnetically started, I mean that there are magnets which accelerate the main shaft to speed to start the engine. The point of this is to remove the need for an APU, saving space and cost on airliners and military jets. 

To provide intake air to the engine to allow it to start up without an APU, there would be a system on the bottom of the engine with small electric fans to push air to the wet section of the engine to start combustion. During the flight the electric fans would be turned off and the intake section would be used like a RAM air intake for the wet section of the engine. The magnets would be powered by the battery in the aircraft, and the small electric fans would be powered by a separate battery in the engine itself.

With all that in mind, would this be viable in a commercial or private environment? Or does the APU do its job too well to replace it?
Three things come to mind:


Magnets are heavy.
Not all compressor and turbine blades are ferro-magnetic.
The starter would only start the engine, and then be dead weight.


Usually, new designs are implemented when they have clear advantages over previous solutions, but I cannot see what problem this would solve. The APU is a very versatile and lightweight piece of equipment that can power up all of the systems of an airplane. Not really anyone's prime target for replacement, I reckon that captain Sully would agree.