Rail craft technology

Years ago, while still on active duty in the USAF, I read a non-classified document discussing the possiblilities of a successful space launch system using a super high-speed rail tunnel that could be built to accelerate a vehicle along a mag-lev straight line until it could "shoot" a craft into the upper atmosphere, where a rocket system could then continue the acceleration to orbital speed.

Just to contrast, the major weight at the time of lift-off of the shuttle is the fuel, to lift the orbiter and fuel into orbit. This system would supposedly be able to reach over 100,000 feet before having to ignite the engines. Again as a contrast, when the Challenger was lost, they had only reached 58,000 feet at the time of the vehicle disruption.

Since that time, however, I never heard anything in public, and obviously didn't hear any classified information on it, or I would not be posting this.

In any case, has anyone else heard about this concept?

Just watched ancient aliens and it talks about that very thing.... How interesting
Id imagine such a device is possible with current tech

havent heard anything

Most of the fuel for the shuttle is used up getting up to 100,000 feet. Once there, largely free of the main atmosphere, accelerating is fairly easy. After all, the SRBs are used up after 2:05, whille the SSMEs fire for another 6:15. However, the SSMEs accelerate the orbiter from 3,500 MPH to the 17,000 MPH orbital velocity. If a rail launch could be accomplised, the size of the craft could be very much smaller that the current shuttle. Plus, if it was expendible instead, it wouldn't need wings, or any other control surfaces, just an RCS system.

Potentially, (that was 15 years ago), an underground rail system could be built, with hardly any visible external footprint. If launched at night, it would be invisible to eyesight, and would produce no visible heat signature as would be seen with a rocket.

I wonder if it would be any cheaper than what we are doing right now. Brilliant idea though.

Judging by who the endorsers of the project were, there were some pretty smart people who had created those plans. It impressed me, but then I never heard from it again.

That makes me believe that either the concept didn't work out, or it did work out, and the project went "black."

ok - some randome real world reasons why this system is impractical

1 - gee force - although it sounds " simple " the geeforce would be astronomical - and the solution of lowering gee force / acceleration by legthening the lauch tube creates other problems usch as


2 friction


3 - " sonic boom " to acieve your claimed 30km altitude BEFORE rocket ignition - the velocity

this will also negate the perception of another ATS member that the launch could be conducted at night in secret

the only real world example of anything that lauched objects to that altitude was the WWI paris gun - and other such ` super artillery `

and the larger or more correctly heavier the payload - the greater the muzzle velocity needs to be

3 - " dead weight " - the ` maglev ` component of the system become dead weight as soon as it leaves the launch tunnel - the ` obvious ` answe is to use a " break away " lauch sled - that falls away like the sabot of a APFSDS [ armoutr peiercing fin stabilised discarding sabot round ] used in tanks

but this requires a masive down range ` saftey zone ` for the sled to be recovered in and its hardly stealthy - another strike for the covert attempt

4 friction par deux - accelerating a maglev object down a 15km track generates a lot of friction - even with NO physical contact - just the boundry layer air interaction

real life developers of high speed magbev train / transit systems are already having to address these issues - at speeds a fraction of what would be required for this system

also - hot magnets are inneficient magnets

5 payload diameter - the tunnel should IDEALLY be as small bore as possible - but that limits payload diameter

incleasing tunnel diameter increases laucher mass - which needs more energy - just to get the laucher out the tube

also the cross section plays a part in the aerodynamic drag of the launch vehicle - bigger cross section - more energy to accelarate it - and ggreater air friction - that in turn has other implications

6 - flight ` stability ` - - an unpowered object lauched from a tunnel is not

the most stable is a sphere - and as its diameter to legth ratio increases - the more unstable in flight it becomes

and unless weight distribution is PERFECT it will tumble anyway

basically - it will tumble - thats why firearms and artillery projectiles are spin stabilised

why not ppin stabilise it you ask ? - why dont you answer that by telling me the rate of spin rquired - and the assciated radial gee force generated - and wether human payloads could survive similtaneous linear [ accelareation ] AND radial loads


its really not that good an idea - sorry

[edit on 10-5-2010 by ignorant_ape]