# Cheap ways of getting to space.

Discussion in 'Architecture & Engineering' started by draqon, Mar 26, 2007.

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1. ### NickelodeonBannedBanned

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Are you using v^2/r?

3. ### nicholas1M7BannedBanned

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draqon,

Recall the movie with those three boys (one was Ethan Hawke) that built a spaceship to get to space.

One of them was gay.

5. ### OliHeute der Enteteich...Registered Senior Member

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Depends what you're launching - cannon shells full of electronics pull about 3,500 G.

7. ### fishtailRegistered Senior Member

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I think the altitude record for a helicopter is 40,000ft.

8. ### draqonBannedBanned

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I can't recall such a movie. No data in my database.

9. ### SingularityBannedBanned

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How long Maglev is needed for reaching the escape velocity ?

10. ### OliHeute der Enteteich...Registered Senior Member

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Depends on the acceleration.

v^2 = u^2 + 2.a.s

Specify final velocity (v), initial velocity (u - zero in this case), acceleration (a) and distance needed (s).
Transpose as required.

Last edited: May 11, 2007

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13. ### OliHeute der Enteteich...Registered Senior Member

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Not required. You can look up the Earth's escape velocity easily (around 11 km/sec)
So you just have to work out what length/ acceleration combination you need from the railgun/ maglev/ lineac/ whatever you want to call it.

Transpose for S gives
(v^2)/2.a = s and just plug in various values for a

So 60.5E6/a = s in metres, using metres/sec/sec for a....
example: at 100 g (rounding g to 10 m/s^2) gives a length of 605 km.
(I think, doing this in my head...

)

14. ### phlogisticianBannedBanned

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... but they don't fly round in circles,.... just how can it be in any way energy efficient to steer something around a track pulling that kind of G?

We're talking about a maglev 'wall of death' here!

15. ### guthrieparadox generatorRegistered Senior Member

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You can do funky things with magnets, as teh large hadron collider shows.
This kind of Em accelerator has been a popular idea for a while. But expensive.

The cheapest way to do it, (And it has been for a decade or three) is to build re-usable launch vehicles, that would bring the cost down to a few hundred dollars per kilogram. (Its currently a few thousand per kilogram). And we can almost do it- computers and composites and fancy alloys mean we can just about do it. Then you launch the bits necessary to capture and steer a carbonaceous asteroid into orbit around the earth. (This will take af ew years, and you might not be able to get insurance)

Then you build your beanstalk. Once that is in place, it can run off solar power most of the time.

But all this would take 20 years or more.

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17. ### NickelodeonBannedBanned

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Wondrous news.

18. ### FacialValued Senior Member

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Possibly the cheapest and most reliable way to get into space is through the developed versions of Gerard Bull's guns that were developed in the 1980's. He worked with Saddam Hussein to build what was then the world's largest gun, but it never became reality. The HARP project showed a lot of promise - all you have to do is to encapsulate the payload in an aerodynamic needle that can effortlessly slice through the air, and an internal mechanism to dampen the g-forces or shock that sensitive components may be susceptible to. The blasting would in total involve less energy than what is stored inside the booster rockets of a conventional launch vehicle.

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I did the maths, in fact, I linked to this thread so you could see the maths were rather unfavourable. A ring 27Km in diameter, to accelerate particles, cost $2Bn. That radius would make the G forces deadly for humans.... and I doubt a structure could withstand keeping an object which became 2000 times heavier confined to a loop, or least it would seriously limit the mass of the payload. Plus, travelling at 11km/s,... that's quick,. Really, really, quick. Slightest glitch or wobble, and the whole thing is one really big train wreck. It would _have_ to be enclosed, ... wind blown debris could be fatal,... all of these things increasing cost and risk. It's not going to happen this way. 21. ### FacialValued Senior Member Messages: 2,219 There's a great video of Esthar's technological capabilities, from Final Fantasy VIII (back in the tender year of 1999). 22. ### PeteIt's not rocket surgeryRegistered Senior Member Messages: 10,166 That ring required much higher precision, because of the much higher speeds involved. An$2Bn for the space program? Not so much, surely. The shuttle program had a budget of \$5Bn or so each year.

It seems you can make a very useful satellite at under 100kg.
LEO velocity is about 8000m/s, which gives us another break... and there might be some tradeoff achieveable by launching extra fuel so that the magnetic launch doesn't have to do all the work.

Say a 4km radius, with launch velocity at 7000m/s, gives us around 1250g.

For a 100kg satellite plus fuel, that makes a 125 tonne weight on the outside of the track, distributed over a fairly small area.

But 125 tonnes... they make bridges that can easily hold that kind of weight, so why not a circular track? Especially if it's set into the ground.

23. ### Kel"Not all who wander are lost."Registered Senior Member

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Cheapest way to get into Space? My sleep deprived vote is for trampolines....REALLY big trampolines...And cheerleaders...cant have trampolines without cheerleaders...

But on a serious note...I seem to remember talk a decade or so ago about mounting a reusable re-entry vehicle to a large airliner, like a boeing 777, flying it up to maximum altitude for the "parent vehicle" and then launching from there. It would alleviate the cost of massive SRB systems and the huge fuel tank that current shuttle missions use. Come to think of it I thought they (being NASA) were going to begin testing of the idea sometime in the past five years or so... Of course with the flood of accidents and budget cuts it may just be a pipedream at this point.