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Program Objectives and Approach
The charter objective for the VTB program is to provide an infrastructure that supports virtual prototyping of next-generation electric systems for Navy vessels.
The effectiveness, efficiency and compactness of robust, fault tolerant systems to manage, control protect, distribute and convert energy in its electrical form, lead naturally to the conclusion that the all electric ship is the ship of the future. This includes, but is not limited to the traction systems.
Of the many challenges for electrical engineers one of the more intriguing is the possible requirement on aircraft carriers of the future for an Electromagnetic Aircraft Launching System, (EMALS), a linear motor system to replace existing steam catapults.
So, a linear motor to take a 50 tonne aircraft from 0 to 135 Kt in 100 meters! That’s around 2.5 g for 2.9 s. Can it be done electrically? In the existing volume? The short answer is yes, but which of all the possibilities with contemporary technology, induction motors, permanent magnet motors, super conducting coil motors, is the best? What is the ideal layout of the magnetic field component and the current carrying components? Which should move and which should be stationary? Even the question, in a linear machine, of the number of "phases"? There exists a very large range of possible options.
This happens to be an ideal situation for VTB. Certainly building any single one of these systems is a massive and expensive project. With VTB a range of possibilities can be explored, modeled and simulated for comparison purposes. The VTB project had been tasked by ONR to develop VTB to explore this range of possibilities.
There are further questions almost immediately:-about the physical scale of such a system, delivering 120 MJ in 2 s, stopping the moving part, here referred to as the shuttle, after the aircraft is launched, the power electronics possibilities, and how to model this distributed / coupled electromechanical system.
EMALS Pages
