Cheap, reliable system to LEO.

Norske · 01-22-2006

Hello. I am brand new to this forum and this is my first thread, so bear with me if this is ignorant or redundant.

In my view, the primary thing that mankind lacks for longterm survival is a cheap, reliable system to put large payloads in Low Earth Orbit. I once read that once in LEO, energy-wise you are half way to anywhere else in the Solar System and the potential resources of energy and materials that are "out there".

I know there have been past threads touching on what I propose, but here goes.

First, I am fascinated by the combination of ramjets, particularly a modification of a particular form of solid fuel ramjet, and a magnelev train type "racetrack" catapult.

During World War II, Nazi Germany was faced by severe limitations in their access to petroleum. On the other hand, they had a relatively plentiful supplies of coal.

One of their scientists, Dr. Lippisch (sp?) proposed a fighter-interceptor that utilized a coal-fired ramjet. It used granulated coal (probably "coke", for purity) in a cylindrical wire mesh container. Oxygen was fed through the coal and partially burned, resulting in carbon monoxide gas. This was then fed into a ramjet like any other fuel and burned to thrust. The exhaust was practically pure carbon dioxide.

Although other fuels are of course possible and/or more efficient I like the idea of using pure-carbon coke since the United States is to coal as Saudi Arabia is to oil. We have been able to make cheap, industrial quantities of pure carbon out of coal for as long as we have had Bessemer converters.

The primary limit of a ramjet is that is must be traveling at least several hundred miles per hour before you can light it off.

Therefore I would suggest a magnelev train type catapult to bring the unit up to ramjet velocities, light the fire, then kick it off the sled it is riding on and let it accelerate up to ramjet speed limits, which as I understand it is about Mach 4 or 5.

Now at this point, someone is going to ask why I am using a standard ram-jet instead of a scramjet, which is theoretically capable of Mach 9 or 10 speeds. I am not a scientist or engineer. I just like the idea of using a plain old ramjet as it seems to me the materials limitations between Mach 4-5 and Mach 9-10 would be significant in keeping the system cheap.

Of course, whether using ramjets or scramjets you are going to run out of atmospheric oxygen.

So, for the final part of the system I envision. I don't see where the jet cares where the oxygen comes from. Lift with standard liquid oxygen tanks. At the point where airbreathing becomes impossible, close the airducts and begin feeding the engine with liquid oxygen, thus turning the system into a composite rocket engine, the rest of the way to LEO.

OK, engineers and space scientists, flame on!

TheBigDog · 01-22-2006

LEO is going to be one of the biggest industries in another 50 years or so as it begins to resemble the international air travel of today. Leaps in economy and safety will drive success and make the industrial megamen of the next generations. Is Rutan going to be the Hughes of space?

One of the more interesting models that I have seen people pitching is the "space elevator" where a cable of sorts that is some 60,000 miles long is teathered to the earth and reaches out into space. Because of centrifugal force the cable would be weight neutral. You would crawl things up the cable into space instead of using propulsion. Objects could be released at low orbit, geo-syncronious orbit, or past there at high escape velocities. I don't think anyone knows how you would make it stand up yet.

http://www.spaceelevator.com/
http://www.space.com/businesstechnol..._020327-1.html
http://science.nasa.gov/headlines/y2000/ast07sep_1.htm
http://en.wikipedia.org/wiki/Space_elevator

Bill

Norske · 01-23-2006

Quote:

Originally Posted by TheBigDog

LEO is going to be one of the biggest industries in another 50 years or so as it begins to resemble the international air travel of today. Leaps in economy and safety will drive success and make the industrial megamen of the next generations. Is Rutan going to be the Hughes of space?

One of the more interesting models that I have seen people pitching is the "space elevator" where a cable of sorts that is some 60,000 miles long is teathered to the earth and reaches out into space. Because of centrifugal force the cable would be weight neutral. You would crawl things up the cable into space instead of using propulsion. Objects could be released at low orbit, geo-syncronious orbit, or past there at high escape velocities. I don't think anyone knows how you would make it stand up yet.

http://www.spaceelevator.com/
http://www.space.com/businesstechnol..._020327-1.html
http://science.nasa.gov/headlines/y2000/ast07sep_1.htm
http://en.wikipedia.org/wiki/Space_elevator

Bill

I have heard the Space Shuttle called "the DC-3" of the space sciences. If the Mercury and Gemini programs were the equivilents of the Wright brothers planes, and the Shuttle is a DC-3, then what I am looking for NOW is the Lockheed Constellation-level ground to LEO system .

A dirt cheap, utterly reliable system to put large payloads into LEO using EXISTING technology and to vastly supplement and/or replace the Shuttle.

A space elevator is a great idea, but it is not currently possible to build one given our materials limitations and technical know-how.

Sure, it may be fun talking about building a Concorde as of about 1935. Nice to speculate about, but just too far to reach.

In my view, you have to go from the DC-3 to the Constellation to the 707 to the Concorde. You just cannot cut the intermediate steps out.

TheFaithfulStone · 01-24-2006

What about taking a blimp and a electric rocket to LEO.

http://www.jpaerospace.com/

Personally, I see some promise in this, but I'm the only one. The ion engines that they currently propose to use are pretty much impossible, but I think they may be on to something in their basic premise, that the way up is not to jump over the cliff, but to scale it slowly.

TFS

Skywyze · 02-14-2006

Quote:

Originally Posted by TheBigDog

One of the more interesting models that I have seen people pitching is the "space elevator" where a cable of sorts that is some 60,000 miles long is teathered to the earth and reaches out into space. Because of centrifugal force the cable would be weight neutral. You would crawl things up the cable into space instead of using propulsion. Objects could be released at low orbit, geo-syncronious orbit, or past there at high escape velocities. I don't think anyone knows how you would make it stand up yet.

http://www.spaceelevator.com/
http://www.space.com/businesstechnol..._020327-1.html
http://science.nasa.gov/headlines/y2000/ast07sep_1.htm
http://en.wikipedia.org/wiki/Space_elevator

Bill

In order for it to "stand up" it would have to be anchored at the far end in geosync orbit. Most proposals I've heard are to use a captured asteroid. The anchor would have to be positioned just far enough outside geosync orbit to make the center of gravity for the whole setup directly in geosync.

As far as materials go, carbon nanotubes show huge promise, if only someone can find a way to make them continuous and weave them together to form a cable, or create a composite that retains the strength and lightweight properties of the tubes.

Pyrotex · 02-15-2006

Howdy,
you have touched on one of my favorite subjects, getting to LEO on the cheap. I work here near (and for) the Johnson Space Center, so this is a common topic around the offices.

The Space Shuttle was the Duezenburg ("doozy") of transportation systems. Rather than being cheap, it was arguably the most expensive way to orbit. Keeping it reliable required an ARMY of high paid engineers, working almost around the clock between launches. Every launch cost between 1.5 B$ and 3B$ -- most of that just in salaries! This yielded a cost to orbit of around (on average) 15K$ to 20K$ per POUND of payload.

Currently, NASA is finally serious about lowering this cost. The new launch vehicle(s) are based entirely on solid rocket boosters for the first stage. Almost as cheap as dirt, very reliable, and as simple as a rocket can get. They are returning to Apollo style capsules and re-entry vehicles. No wings, no "pilots" -- just heat shields, parachutes and WWII vintage aircraft carriers parked out in the Atlantic.

Upper stages? They will still use liquid fuel rockets, but it will be variants of the Shuttle Main Engine (SME). No new development costs. Even the huge Heavy Lift Booster we are proposing, will have five SME's and two strap-on "solids". (I don't want to hear any jokes about NASA making "strap-ons"!)

Upper stages. Well, there is a competion going on right now (I'm helping to write one of the proposals!) to make upper stages from entirely off-the-shelf (OTS) hardware and software. Again, no massively expensive research efforts trying to develop new technologies. We hope to lower cargo costs to LEO to around 5K$ to 8K$ per pound.

Long term? My money is on the Space Elevator!!!!!

InfiniteNow · 02-15-2006

Quote:

Originally Posted by Pyrotex

Even the huge Heavy Lift Booster we are proposing, will have five SME's and two strap-on "solids". (I don't want to hear any jokes about NASA making "strap-ons"!)

Hey there, spaceboy... is that a rocket in your pocket, or are you just happy to see me...

You know, I would never have said anything had you not suggested it...