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NASA engineers are developing a radical new form of launch that begins aboard an electrified track similar to that of a rollercoaster.  (Source: NASA)

The sled would then fling a scramjet into the air, which would activate and rocket to the upper atmosphere. Once in the upper atmosphere, the scramjet would fire a capsule launch vehicle into space as the final step.  (Source: NASA/Artist concept)
New launch system could be used for manned launches and satellite launches

NASA's budget may be cut, but that hasn't stopped the first international organization to put a man on the Moon from dreaming big.  One key question the agency is looking at is what the next big thing in space propulsion will be.  NASA and foreign space agencies have examined plasma enginesion enginesnuclear-powered designs, and solar sails, but these technologies lack the impulse and thrust to accelerate a launch vehicle into orbit. 

However, NASA's latest proposal may be the most creative idea of them all and has the potential to be relatively affordable.  The new proposal starts by placing a sled on electric tracks -- NASA's sled needs to reach a whopping 600 mph (appr. 1,000 km/h).

At the end of the track, the passenger vehicle, which rests atop the sled, will be flung off, launching at extreme speed.  The passenger vehicle would be a wedge-shaped aircraft, with scramjets aboard, which would activate upon launch.  Those scramjets would accelerate the aircraft to Mach 10.

Wings would gradually angle the craft into the Earth's upper atmosphere.  At the boundaries of the Earth's atmosphere, the scramjet would fire the actual spacecraft -- a capsule.  The maneuver would be akin to firing a round out of a barrel

By using mechanical motion to launch the craft, instead of expensive chemical boosters, the cost of launches could dramatically decrease.

NASA's Stan Starr, branch chief of the Applied Physics Laboratory at Florida's Kennedy Space Center, says the technology to achieve this type of launch isn't that far away.  In a released statement, he explains, "All of these are technology components that have already been developed or studied.  We're just proposing to mature these technologies to a useful level, well past the level they've already been taken.  Essentially you bring together parts of NASA that aren't usually brought together."

Engineers at NASA and the U.S. Air Force have worked on a variety of scramjet projects thus far, including the X-43A and X-51 (a missile design).  So far these programs have had a couple of successful launches and tests under their belt, raising hopes that the technology can soon be applied to projects like the launcher.

Mr. Starr and other NASA engineers have assembled a proposal to build the system, which they're dubbing the Advanced Space Launch System.  They're seeking grants from a variety of sources.

Under the plan Langley Research Center in Virginia, Glenn Research Center in Ohio, and Ames Research Center in California would build and test the parts of the hypersonic aircraft.  Dryden Research Center in California, Goddard Space Flight Center in Maryland and Marshall, along with the Kennedy Space Center would engineer the rail track.  The plan calls for an actual two-mile long test track to be laid down parallel to the crawlway that the Shuttle used to be transported along to Launch Pad 39A.  Mr. Starr comments, "I still see Kennedy's core role as a launch and landing facility."

The 10-year plan for the launch platform calls for the program to begin with launching small drones -- like those used by the Air Force -- into orbit.  This would be followed by satellite launches.  If all goes according to plan, the system could eventually be used for low-cost manned mission launches, as well.



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Mass driver
By AnnihilatorX on 9/15/2010 11:14:52 AM , Rating: -1
This is exciting
I thought people calculated that mass drivers are not economical on Earth

1000 km/h = 277 m / s so it's way below escape velocity so they still need chemical fuel while in air. Rocket can propel a shuttle from 0 to 277m/s in 15 seconds assuming 20m/s^2 acceleration. So all they saved is about 10 seconds of fuel? Of course this is very rough calculation as mass is expelled from rocket making acceleration faster with less fuel.




RE: Mass driver
By Belard on 9/15/2010 11:27:57 AM , Rating: 5
Remember, the key is scramjets which uses much less fuel, but only work at high speed. The prototypes needed to be launched by high-speed crafts in order to start the engines.

So, hitting 600+MPH on the ground could be safer than the shuttle/rocket systems we have today if the delivery vehicles are smaller, have less full and complicated systems.


RE: Mass driver
By tallcool1 on 9/15/2010 12:42:21 PM , Rating: 2
Marty McFly and Dr. Emmett Brown used the magical speed of 88 MPH.
http://en.wikipedia.org/wiki/File:Delorean5.jpg


RE: Mass driver
By roadhog1974 on 9/15/2010 7:53:47 PM , Rating: 2
but how will they generate the 1.21 gigawatts?


RE: Mass driver
By Ammohunt on 9/15/2010 1:58:18 PM , Rating: 2
They chew through fuel though the Fuel tanks on this platform would be massive.


RE: Mass driver
By emoser96 on 9/15/2010 8:39:33 PM , Rating: 3
The real problem is the speed of sound is ~760mph at sea level. They're proposing to accelerate the "wedge" to ~600mph and expect scramjets to light? You need to be going around mach 4 to get an effective scramjet startup. Less than Mach 2 and you don't even really want a ramjet. This doesn't even account for the absolutely RIDICULOUS dynamic pressures an air/spacecraft would have to endure traveling > mach 1 (or 3-4 for a low speed scramjet startup) at sea level.

Maybe they'll launch from the himilayas???


RE: Mass driver
By FITCamaro on 9/15/2010 8:50:21 PM , Rating: 3
I hear they plan to use Chuck Norris as a booster.


RE: Mass driver
By emoser96 on 9/15/2010 8:39:34 PM , Rating: 2
The real problem is the speed of sound is ~760mph at sea level. They're proposing to accelerate the "wedge" to ~600mph and expect scramjets to light? You need to be going around mach 4 to get an effective scramjet startup. Less than Mach 2 and you don't even really want a ramjet. This doesn't even account for the absolutely RIDICULOUS dynamic pressures an air/spacecraft would have to endure traveling > mach 1 (or 3-4 for a low speed scramjet startup) at sea level.

Maybe they'll launch from the himilayas???


RE: Mass driver
By roadhog1974 on 9/15/2010 9:37:57 PM , Rating: 2
Launching from tibet certainly makes technical sense.

Can't see it happening.

most countries want to launch locally given the military
implications.


RE: Mass driver
By guacamojo on 9/15/2010 11:33:06 AM , Rating: 5
The mass driver is there just to get up to the minimum operating speed for the scramjet. By itself, it doesn't save much fuel.

The scramjet stage does most of the work of accelerating to escape velocity. Since it's an air-breathing engine, you don't need to carry oxidizer, just fuel. That dramatically cuts down on launch weight.

Then the spacecraft itself is kicked into orbit by pushing away the scramjet stage (which is itself reusable, I assume) or by chemical rocket.

It's an interesting concept.


RE: Mass driver
By AstroGuardian on 9/15/10, Rating: 0
RE: Mass driver
By ekv on 9/15/2010 12:46:30 PM , Rating: 2
quote:
The mass driver is
... the fuel you don't have to carry.

Yes, interesting. But, dare I ask, what about the birds?


RE: Mass driver
By Mitch101 on 9/15/2010 12:49:12 PM , Rating: 3
Fabio is working on that.


RE: Mass driver
By Hafgrim on 9/15/2010 6:28:24 PM , Rating: 2
High energy microwave antennas on either side of the tracks that focus down the line ahead of the launch vehicle should easily do the trick of keeping the launch vehicles safe from any birds & in dramatic fashion I might add. =)


RE: Mass driver
By DanNeely on 9/15/2010 10:03:31 PM , Rating: 4
Yup. The scramjet will save a lot of fuel. It's the only realistic near future technology that can significantly reduce the cost of launching something into orbit.

Doing a back of the envelope calculation, a 1000m/s launch track + mach 10 scramjet will reduce the amount of fuel needed to reach mach10 by a factor of 2.2 allowing for either a much smaller total rocket or a much larger upper stage + payload combination. At mach 25 (slightly under orbital velocity of mach28.5) the ratio increases to 6.5:1. At mach 28.5 the ratio goes up to 8.3:1 but this would be undercut somewhat due to the need for a circularizing rocket burn once the ship reached space (otherwise it's in a ballistic missile type orbit and would reenter shortly after leaving the atmosphere).

As back of the envelope math these calculations ignore various fiddly bits that can significantly alter the final results. The relative mass of the ramjet vs conventional rocket module would be a major factor in where the actual numbers end up. For a real world example a large chunk of the higher performance of hydrogen rockets over kerosene or solid fuel rockets is lost because cryogenic hydrogen is bulky and the larger fuel tanks increase the parasitic mass of the rocket itself.

For anyone curious about my math, the rocket equation when solved for the mass ratio is:

m0/m1 = e^(deltav/g/Isp)

e = 2.71
g = 9.81m/s
Isp (kerosene rocket) = 350s
Isp (kerosene ramjet) = 1250s

deltaV (kerosene rocket) is 3400, 8500, or 9700m/s in the three cases above.

deltaV (kerosene ramjet) is 2400, 7500, or 8700m/s (remember the ramjet is leaving the launch track at 1000m/s).

Specific impulse (Isp) is a measure of how long 1kg of propellant can produce a thrust of 1g. Since only ~28.1% of the propellant in a kerosene rocket is kerosene (the remainder is oxygen) a ramjet, by getting its oxygen from the air, will have 3.56 as much kerosene per kg of propelant and be able to burn for 3.56x as long giving an Isp of 350*3.56 ~= 1250s.

PLugging the numbers above into the rocket equations gets mass ratios of 1.22, 1.84, and 2.03 for the scramjet vs 2.69, 11.88, and 16.86 for the conventional rocket. These numbers divided by each other are what I cited in the 2nd paragraph.

http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_eq...
http://en.wikipedia.org/wiki/RP-1


RE: Mass driver
By AssBall on 9/15/2010 11:37:13 AM , Rating: 2
That 10 seconds of fuel is probably about 20 times less total volume though. The scramjet has very efficient fuel/thrust/aerodynamic lift ratio, and a new lightweight vehicle will not be trying to drive 4,250,000 lbs directly perpendicular to gravity (rough shuttle weight @ liftoff).


RE: Mass driver
By theArchMichael on 9/15/2010 1:23:22 PM , Rating: 2
True, plus You wouldn't need the disposable dildo shaped fuel tanks to help penetrate the atmosphere.


RE: Mass driver
By MozeeToby on 9/15/2010 11:40:58 AM , Rating: 2
I think the idea is that the cannon launch gets them up to a speed that a SCRAM jet can work. SCRAM jets are nice because unlike rockets they are air breathing, they need to take fuel up but not an oxidizer to burn it with.

There are a lot of downsides, only some of which are addressed by a mass driver launch. First is that they can only work at extremely high speeds, you need to boost them up to those speeds using some other engine technology. Second is that no one has ever flown one anywhere close to orbital speed (Mach 25 about). Finally, even if you can reach orbital speed you still need a relatively small rocket to actually insert yourself into orbit, since the SCRAM jet uses air as its oxidizer you can't use it at orbital altitudes.


RE: Mass driver
By sealsix6 on 9/17/2010 8:37:40 AM , Rating: 2
I remember this launch idea(rail acceleration) was kicked around on Popular Mechanics in the 90's. They went for the maglev variant on a mountain slope.

I think the research pointed to massive cost prohibitors and it was canned.

Maybe now they can make it work. Maglev plus vacuum tube/tunnel to an altitude of maybe 4000m.


RE: Mass driver
By SimBoB on 9/15/2010 12:26:42 PM , Rating: 2
The Fabio pic is rather appropriate- Just because it's technically possible for a passenger vehicle to be accelerated to 600mph and then "flung off" at the end of the track (along with a fueled launch vehicle to make up the other 15,000mph) doesn't mean it's the best way to fly.

Nevertheless, sled launch has been studied for nearly 40 years- here's a partial list:
http://www.astronautix.com/fam/slenched.htm

And some video of an actual sled launch:
http://www.youtube.com/watch?v=sBZN3c7O9wc&feature...

B)


RE: Mass driver
By theArchMichael on 9/16/2010 9:09:34 AM , Rating: 2
Ok, I give up... what does fabio have to do with reusable space vehicles???


RE: Mass driver
By SimBoB on 9/16/2010 1:22:35 PM , Rating: 2
"A politician stumbles over himself... Then they pick it out. They edit it. He runs the clip, and then he makes a funny face, and the whole audience has a Pavlovian response." -- Joe Scarborough on John Stewart over Jim Cramer














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