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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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By Hammer1024 on 9/15/2010 1:46:08 PM , Rating: 3
Ah well... Tis another day and another abridged article...

First up in the batters box: "NASA's sled needs to reach a whopping 600 mph (appr. 1,000 km/h)."

600 mph is 880 ft./sec. or Mach .79 at sea level in a standard atmosphere. In order to start and maintain scram jet (Supersonic Combusting Ram Jet) operation, the thrust chamber fluid (burning air/fuel mix) velocity cannot fall below Mach 1. The typical transition velocity is in the Mach 6 range, so we'd need in the neighborhood of 6699 ft./sec. just to start and maintain the burn. That's 4567 MPH at sea level.

So a scram jet off the deck is not feasible; we'd melt any large cargo capable (human or other) structure created from thermal heating. About the only thing we do have that goes that fast or better at sea level is a thermonuclear reentry vehicle and it doesn't last long enough to matter.

So a combined cycle air breathing engine is a must; an uprated SR-71 type if you will: Turbojet/fan, RAM, then SCRAM.

The turbofan/jet would be good up to about Mach 2 - 2.5, the ram jet then takes over to about Mach 5.5 - 6 which then transitions to scram jet.

Next up: ... The maneuver would be akin to firing a round out of a barrel.

Not a good idea... Not at all. At those speeds, Mach 10 or so, the scram jet vehicle is flying faster than any bullet. The only thing you'd do is fire the bullet and have it come right back through your wind screen... See the example of the A-12; the pre SR-71 interceptor. And the separation dynamics are UGLY!

Forget staging in the atmosphere at those speeds. Either get completely out, then stage so there are no aerodynamic drag issues, or fly the entire vehicle to LEO.

For the LEO option, one would add the closed rocket motor cycle to the engine: Seal off the inlet and push LOX & LHX/Kerosene into the engine. Back to the SR-71 example:
Turbojet/fan, RAM, SCRAM, rocket.

I believe I remember from back in the 70's that the fly to LEO option was the overall best solution for payload to vehicle complexity and throw mass: Lightest vehicle to payload option using an air breathing launch vehicle.

Also, since most active research is into getting a scram jet to burn petroleum (Kerosene) products, it stands to reason the LOX - Kerosene cycle would be the way to go; Kerosene's easy compared to LHX.

The downside of Kerosene is that once on orbit and the fuel cooled, one couldn't restart the engine since the Kerosene would be one big ice block.




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