Getting into Orbit with Rockets

[marginaleye]

I'm trying to design a low-tech air-breathing S.S.t.O. vehicle, using T4 FF&S. I know that, at some point, such a vehicle will have to switch from ramjet- over to rocket-propulsion for insertion into orbit, and that it ought to be going pretty fast (around Mach 20-25) when it does so. I don't, however, know how much thrust is required, and how long the rocket has to burn, for that final push up into orbit. Since rockets consume a lot more fuel that ramjets, this is a serious problem. Can anyone either help, or point me towards where I might find answers? Thanks!

 

[shield]

The Megatraveller Hard Times has a low tech spaceship design system. basically you can use air breathing engines to get you to the orbital transit time. If you blast up like a rocket it is 90% of the time to get into orbit. If you fly up like a plane it takes the 90% x 10 (much easier but slower). From there you use your rocket to blast into orbit for 10% of the time required to reach orbit.

Both the TNE main rule book, and the hard times book have ground to orbit transfer times for a number of Gs acceleration.

Hope that helps

cheers
Richard