[jkqwzsoo]

As discussed in the video, the SpinLaunch has the advantage that the acceleration to launch velocity is done in vacuum without reaction mass, so they can use a relatively heavy vehicle. The heavy vehicle obviates the issue you discuss, since there is more kinetic energy stored in the heavier vehicle than in a chemically-launched vehicle (which in this case needed to be light enough to be accelerated to velocity in 5 seconds). Thus, the fraction of energy lost as heat will be lower.

Again, this is because the vehicle can be accelerated electrically under vacuum until it reaches the required velocity. The heavy mass (in the vehicle’s nose cone) is not part of the orbital vehicle.