A launch system accelerates a mass from rest to a target speed over a fixed distance, then hands off. Because a linear induction motor drives the vehicle directly and its thrust does not rely on wheel-rail grip, it delivers the same push in rain, ice or on a grade that would defeat a friction drive.
The launch duty cycle
A launch is a short, intense burst rather than continuous running: full thrust from standstill through the launch section, then coast or hand-off to another system. In a single-sided LIM (SSLIM) a primary works against an aluminium or copper reaction plate over a steel back-iron, which adds a significant normal attraction to the steel; a double-sided LIM (DSLIM) drives a bare conductive fin from both sides so the opposing normal pulls largely cancel in the frame, and it can approach twice the active-face thrust for a given track width under comparable current, gap and thermal limits. We size the motor around the specific profile the launch has to hit, not a generic rating.
Target speed and acceleration
The launch is defined by three numbers that trade against each other: exit speed, launch length and peak acceleration. Field speed is set by the drive frequency and the pole spacing, and slip - the small difference between field speed and vehicle speed - is one of the variables that set thrust, so as the vehicle speeds up the drive sweeps frequency to keep pulling. Thrust ultimately comes from the air-gap power divided by the field speed, refined with longitudinal end-effect and transverse edge-effect corrections, which matter more at the high field speeds a launch demands.
Repetition rate and reaction-plate heating
A launch that fires once an hour and one that fires every ninety seconds are different machines even at the same peak thrust. Each launch dumps energy into the reaction plate and primary as heat, and the cycle time sets whether that heat clears before the next launch or accumulates. We model the thermal path across the full repetition rate, because the sustainable duty - not the single-shot peak - is usually what caps a high-throughput launch.
Power and inverter sizing
Launch drives are almost always inverter/VFD fed so frequency can track the vehicle from zero to exit speed; direct-on-line only suits niche fixed-speed duty. The peak electrical demand is brief but large, so inverter rating, supply capacity and any energy-buffering all follow from the acceleration profile and repetition rate rather than from average power. We size the drive against the same duty and thermal picture used for the motor, so the two are matched.
Coaster, sled and industrial/aerospace launch use cases
The same adhesion-independent, contactless push suits a range of launches, each stressing a different part of the envelope.
Roller-coaster launch
High peak acceleration over a short section with a fast, repeatable cycle - here repetition rate and plate heating tend to govern, not the single launch.
Test and catapult sleds
Very high exit speed on a long track, often at low repetition rate, so peak thrust and end-effect corrections dominate the sizing.
UAV and aircraft launch
A controlled acceleration profile to a defined release speed, where hand-off accuracy and a light passive vehicle can favour a wayside long-primary layout.
Industrial and material handling
Repeated accelerate-and-transfer moves where reliability across a heavy duty cycle matters more than outright peak.
Whichever it is, we size with equivalent-circuit models, cross-check with FEA, run the full launch profile in route/duty simulation and check thermal limits before cutting metal.
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