Are There Viable Non-Rocket Methods for Atmospheric Launches?

[deathil93]

Hey guys,

I'm looking into the various spacecraft propulsion methods and I was wondering if there is any concept or theory for a non-rocket based atmospherical launch, besides air launch, electromagnetic rails, hybrid rockets/engines etcetra...


Thanks :)

 

[Danger]

Welcome to PF, Deathil93.
You know, the "etcetra" (sic) in your post pretty much eliminates any alternatives.

 

[deathil93]

Welcome to PF, Deathil93.
You know, the "etcetra" (sic) in your post pretty much eliminates any alternatives.

Yeah I didn't put the question correctly. I mean, are there any non-rocket launch concepts excluding structure aided launch such as the magnetic rails or space lift or air launch. Basicaly a non-rocket engine that you slap onto the craft and it flies off to space.

Another question, can Ion thrusters, such as the VASIMR and MPDT variants, be adapted to be used in both the atmosphere and outer space?

 

[Ryan_m_b]

I don't think ion thrusters of any sort could be used unless you found a way to make them particularly high thrust (and even then I'm not sure if there wouldn't be safety issues).

Beamed-powered propulsion is a possibility: in this system a beam of light or even a particle beam shot from the ground (powered from a ground based system) to the payload to propel a payload without carrying it's own fuel or propulsion. As for "slapping propulsion on and sending it to space" it's going to have to be some sort of rocket because once you are in high-atmosphere you've got negligible atmosphere to use for any kind of air-breathing engine though as you mention in your OP there are http://www.reactionengines.co.uk/sabre.html . More efficient than a chemical rocket could be some form of nuclear rocket such as nuclear thermal or nuclear salt-water (not really advisable if you don't want to spray radioactive particles throughout the atmosphere).

Lastly a very different proposal could be something like a skyhook, space fountain or space elevator.

 

[Travis_King]

You've also got to consider your payload. Do you want to launch a lot of mass? You'll need a lot of propulsion. Do you want to launch humans? You'll need to limit acceleration yet maintain thrust long enough to reach your desired velocity. What's the stuff made of? Is it going to be able to return to Earth, or is it a one-time deal.
Where do you want it to go? LEO? Geo? How quickly, etc.

Different approaches have their varied strengths and weaknesses. It just so happens that with today's technology, rockets are best at both keeping humans alive, and lifting payloads at an acceptable or plausible (what you might call) payload:craft ratio.

 

[Ryan_m_b]

On the subject of rockets and alternative ways to launch I'd be very interested to see if SpaceX can pull off their reusable rocket plan (I don't mean to go off topic but if you are looking for alternative ways to get into space you might be interested in future rocket technologies that may be far different to today):

 

[Pkruse]

Back in the 60's & early 70's Gerald Bull experimented with launching packages into orbit with a giant cannon. He demonstrated that he could attain enough energy for the task, but could not control the orbit. Packages were small, and back in those days satellites were big. So it was not a viable concept. He then spent a number of years skirting the law and specialized in military applications. He built a research center on the US/Canada border, hoping to exploit the most convenient laws of both countries. Ended up building the giant “Babylon Gun” in Iraq.

I suspect that a modern light gas gun could provide a projectile with an equivalent amount of energy, but it is no more practical than the Bull design. Current efforts by the US Navy to develop a weaponized rail gun may lead to the ability to impart enough energy to a projectile to put it into orbit. If so, we would be able to overcome Bull’s flight control problems of the 1960’s. The rail gun was evaluated as a possible means of launch in the 1950’s. The conclusion was that it was a viable idea, but only if we could find enough power to run it. At the time, that would have equaled about half the power consumption of a city the size of Chicago. But a medium sized gas turbine could handle the task today.

 

[Pkruse]

As long as we are off topic:

The Space Shuttle proved that a reusable launch system is a whole lot more expensive than an expendable system. Certainly, we could make vast improvements to what we did with the Space Shuttle, but it would still be more expensive because we have also made great improvements in expendable systems that greatly reduce the cost.

What I see as a very viable idea is something like the Pegasus system, which some of the current private companies have copied and pretended like they invented it. Carry it as high as practical in an airplane, release it, and let expendable solids do the rest. Expendable solids are very cheap compared to all other options, and an airplane ride hardly costs anything while imparting a substantial part of the energy required to the vehicle.

Of course, a manned system requires the ability to return safely; but I’m betting that the Orion capsule will always be orders of magnitude cheaper than any of the other proposals that I’ve seen in the press, and of course the Orion is reusable. It is also highly versatile and easily adaptable to many different types of missions.

The single most practical thing we can do to minimize cost is to learn from the Sea Launch program. Build a floating launch platform and launch near the equator due south of Hawaii in an area far removed from ship traffic. Eliminates billions of dollars worth of safety precautions required when launch near populated areas.

 

[HowlerMonkey]

There is no proof the shuttle proved more expensive because there is nothing else that has the capability it does.

It would have to be compared to something of the same capability.

 

[Ryan_m_b]

There is no proof the shuttle proved more expensive because there is nothing else that has the capability it does.

It would have to be compared to something of the same capability.

That depends, what capabilities are you referring to?

In terms of cost to orbit:

Space Shuttle incremental per-pound launch costs ultimately turned out to be considerably higher than those of expendable launchers: by 2011, the incremental cost per flight of the Space Shuttle was estimated at $450 million, or $18,000 per kilogram to low Earth orbit (LEO). By comparison, Russian Proton expendable launchers, still largely based on the design that dates back to 1965, are said to cost as little as $110 million, or around $5,000/kg to LEO. When all design and maintenance costs are taken into account, the final cost of the Space Shuttle program, averaged over all missions and adjusted for inflation, was estimated to come out to $1.5 billion per launch, or $60,000/kg to LEO. This should be contrasted with the originally envisioned costs of $118 per pound of payload in 1972 dollars ($1,400/kg, adjusting for inflation to 2011)

http://en.wikipedia.org/wiki/Criticism_of_the_Space_Shuttle_program

Another thing to consider is whether or not the space shuttle delivered on its promise. Rather than being a cheap and quick way to get to orbit frequently (IIRC a shuttle was meant to be able to perform 50+ flights per year) it proved to be incredibly expensive with rare launches. Obviously what's done is done and there are good economic and technological reasons for why the shuttle didn't meet its goals. However the question becomes if we can learn anything from the shuttle program about whether or not attempting something else would have been better e.g. what would NASA be like now if instead of funding the shuttle program it had funded something like Nova.

 

[Pkruse]

Putting people on a cargo litter greatly increases cost. Worse in the case of the SS is that processing tasks were serial not parallel. All proposed lifters fix both problems and will be much cheaper.