Ok, I understand the nature of my question but anyway why the rockets are not tossed up before launch. It could introduce a huge handicap for a rocket in terms of reduced distance it has to travel, momentum it has to reach, etc, etc, etc and eventually increase the maximum weight the rocket can carry with little to no changes in rocket technology itself.
There are mines in the world that go as deep as 5km. So digging a 5km deep hole and building a tossing platform in it that would accelerate a 100+ ton weight of the rocket is of course a challenge but this seems not a rocket science compared to making an unstable rocket actually fly.
If I didn't let any mistakes assuming no air friction exists such jump at it's time t [seconds], with platform constantly accelerating at g [m/s^2] starting acceleration at y0 [meters] and finishing acceleration at y1 [meters] with initial speed of dy0 [m/s] could be described by equation:
So for -5km hole and constant acceleration of 5g it would take 14.28 seconds of acceleration, 700 km/h (435 mph) of speed and would push the rocket 31 km high in the sky until it starts falling.
