Mag lev Mass Accelerator

[FREEFALL1984]

Would it be possible to send an payload into space with only a series of small boosters to circularize the orbit.

The idea is simple, a curved maglev track about 50km long, the start of the track is above ground the and it dips into the ground by several km, the other end of the track comes out the side of a mountain a half dozen km above sea level. The payload is loaded into a transport vehicle at the start of the track which has little more than a beefed up heat shield and ballast tanks to add mass if the payload is underweight. it also has a small liquid fueled rocket to enable it to circularize and some RCS thrusters to assist with docking. The transport vehicle is designed to be very aerodynamically efficient and stable in order to minimize drag. Then bang, the payload is accelerated to high enough speeds to both overcome the drag of the atmosphere and to maintain enough speed for a simple circularization burn. So here's some questions,

Roughly how fast would you need to be traveling to reach orbital speeds AFTER you overcome atmospheric drag and reach orbital altitudes to perhaps rendezvous with a station in space based on a 15 ton craft.

based on the described track, how many Gs would the payload need to endure.

I personally imagine it would be well beyond the realms of possible, even if there was a way to produce enough energy to send 15 tons of payload to several times orbital velocity against air resistance, to do it within just 50km would be a huge explosive release of power, also the heat shielding would need to be made from imaginary materials since the temperatures endured would be far higher than reentry.

[Dkmdlb]

Heinlin's wonderful "The Moon is a Harsh Mistress" has catapults like this to ferry cargo from the moon to earth, and then at the end, one is built on on earth.

http://www.technovelgy.com/ct/content.asp?Bnum=1118

[Sillychris]

Why limit yourself to one lap? You could do it LHC style and accelerate your payload on a circular track at as few G's as you want before releasing it onto the straight bit when the required velocity is reached.

[Idobox]

The main problem with mass accelerators on Earth is the massive atmospheric drag. Traveling at 8km/s in the lower atmosphere is not fun.

Typically, designs use linear acceleration, because you need absurdly large loops to deal with centrifugal force at suborbital speeds.

Check startram and tbfg.org to get an idea of the issue.

[sgt_flyer]

you'll need more than just a heat shield to overcome the drag at low altitudes.

first, your acceleration tube would need to be kept at near vacuum for acceleration - and you'll need some form of shutter (plasma windows are envisaged)

- the tube would close with a normal 'door' and the plasma window would only activate when this normal door is opened - just to let the spacecraft fly through.

the problem comes after leaving the tube : at the speed you'll need to go to overcome the encountered air, you'll face interesting consequences (imagine the heat of flying at more than orbital speeds in low atmosphere - i don't know if any heat shield would be able to withstand that - as you'll need this much speed to get out of atmo - you'll lose a lot of speed during the ballistic ascent due to drag. one possibility would be to use some form of MHD plasma shield (your spacecraft would have a low density 'plasma' coating during atmospheric ascent to protect it from the drag) (kinda like supercavitating torpedoes, but where those torpedoes use a air bubble to lower their drag in water, you'll use a plasma bubble to lower your drag in atmo)

[Idobox]

Plasma doors of this size would be extremely difficult to build, and would still be quite leaky. I would use a normal door.

To survive the heat, the most commonly proposed solution is a skin cooled by water. It is a very heavy solution, but water is amazing at sinking heat, and the launch cost should be much lower for a mass driver.

[FREEFALL1984]

Instead of a door a latex sheet could be stretched across the opening, the ship would have to burst through it and of course the pressure would only be able to be "quite low" since the sheet would distort

[ZetaX]

If you go for circular, then apart from the centrifugal forces by the circle, you will also get relevant coriolis forces unless you build the full circle parallel to the equator.

[roadburner99]

would the mass accelerator be able to be used to send ordanance to its destination?

 

[Nibb31]

Dunno why you are necroing, but a mass accelerator shooting ordnance as a weapon would be called a railgun.

https://www.youtube.com/watch?v=o4ZqfEJTGzw

[DBowman]

Light gas guns look fun, sort of a giant hi-tech potato cannon. These guys look to be out of business now but there are some details of what they had in mind quicklaunch.com from archive.org. A 400m to 1000m gun floating in the ocean (to make it easy to point) that shoots 50 kg to 1000 kg projectiles to a LEO apogee. I cannot recall what the plan was wrt to atmospheric heating low down, it might have been 'go fast enough and the heat load isn't too bad' - but you'd think it would take something better than that.