Space programs, From launch to Orbit.

[Zolar V]

@ZolarV Recently i was reading a bit of a bad thread on the NASA Space Program, and how it lacked any imaginative propulsion systems. NASA's current propulsion system is a chemical system that reacts hydrogen with oxygen. However in their labs they have done some significant work on ION thrust, space foil (kite), and even nuclear explosion type propulsion systems.

 

I thought for a few minutes on the subject and came to the conclusion that all of the thrust systems that NASA has built are rather bland. They all are trying to achieve orbit in one way, that is quickly.

 

What if we didn't need to reach space fast? Why not just slowly lift something up into space, is there some need to speed a payload into orbit?

 

Here is my idea, lets build a freaking giant slab of land, use 2 nuclear reactors to lift up the piece of land similar to a airship, and slowly move the slab of land into space. Or rather have a sort of vehicle on the piece of land that could take off at 40,000 or 50,000ft into space. Sure the energy required would be much higher. But it's nuclear, it doesn't need to generate much thrust, it just needs to have constant thrust.

 

Oh and the 2 nuclear reactors power turbine/fans that suck air through them and push it out underneath the slab of land. Imagine your massive cooling stacks, housing fan systems that suck and push air for propulsion.

[Cap'n Refsmmat]

Here is my idea, lets build a freaking giant slab of land, use 2 nuclear reactors to lift up the piece of land similar to a airship, and slowly move the slab of land into space. Or rather have a sort of vehicle on the piece of land that could take off at 40,000 or 50,000ft into space. Sure the energy required would be much higher. But it's nuclear, it doesn't need to generate much thrust, it just needs to have constant thrust.

 

Oh and the 2 nuclear reactors power turbine/fans that suck air through them and push it out underneath the slab of land. Imagine your massive cooling stacks, housing fan systems that suck and push air for propulsion.

 

How would these get into space? There's no air at high altitude to suck through your fans.

 

You might be interested in the unconventional designs of Scaled Composites:

 

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

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

[Janus]

Trying to lift slowly into orbit would be highly inefficient. You would be spending a great amount of energy/fuel just fighting gravity. A fast route serves two purposes: you spend less time fighting gravity until you reach orbit and you burn most of your fuel while you are close to the ground, meaning that you will not have to waste the energy it would take to lift that fuel.

[Zolar V]

How would these get into space? There's no air at high altitude to suck through your fans.

 

You might be interested in the unconventional designs of Scaled Composites:

 

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

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

 

I have actually read and have been following both of those projects since their origin. They are in fact, great ideas on getting orbital and sub orbital vehicles into their respective orbit without having to carry so much fuel and be extremely large to accommodate said fuel.

 

 

Yes, i understand that it would be energy inefficient, however the slab of land could act as a floating sub-orbital launchpad for space vehicles. The vehicles themselves not unlike Virgin Galactic's designs would require less energy to escape earths gravitational pull because they would be launching from 30,00-60,000 ft. The floating launchpad though would require a tremendous amount of energy, doesn't need to be highly energy efficient, it only needs to be able to produce a sufficient and stable amount of thrust for a long period of time. Such as it is, regular nuclear reactors with a bit of a different design for the cooling mechanism could be outfitted to suit this purpose.

 

With the floating launch pad, you could in fact fly material and vehicles via regular cargo planes to it. It would serve as a sort of staging ground and command center to space operations.

[Cap'n Refsmmat]

How about very large blimps?

[Zolar V]

How about very large blimps?

Great idea, you could attach or otherwise modify the original design of a floating launchpad to include a static structure that exerts a upward force.

 

Would you suggest that it be hydrogen inside a balloon following traditional blimps? Or something else? Maybe if you made a sort of cup type shape on the underside of the launchpad, affixed a skin over the cup and then created a vacuum within the cup structure. The mouth of the cup pointing down, and the bottom of the cup affixed to the slab.

 

-------A--------A---A--A---A--A------- < like that, the opening is pointing to the ground and the bottom is affixed to the structure.

 

you could also use blimps as a energy efficient way to ferry materials from the ground to the launchpad itself too.

 

on a side note, what type of college would i need to get into to design these types of things? i mean i have many ideas that encompass a lot of different subjects. However something like this or one of my other ideas that are "engineering" would be easy to create and sell.

 

In other words where do i have to go to start getting going on creating my ideas? Also how do i get noticed in that particular world?

[Danijel Gorupec]

Why not just slowly lift something up into space...

 

I am sure you will be fascinated with space elevators (just google for "space elevator", there are nice images) - I was, and still I am.... NASA also knows about it.

[Mr Skeptic]

Looks like plenty of misunderstandings about spaceflight here. In space there's no air, so fans won't work. Near space there's very little air, and fans become vanishingly ineffective. However if you do have air, the air is very useful to the extent that the specific impulse of a jet engine beats even that of most advanced/theoretical rocket engines, however it also limits it to working only where there is air. As for the need for speed, there's two reasons. One is that hovering costs you both energy and fuel, and another is that to reach a given orbit you need to reach the proper speed for that orbit. And nuclear powered craft still need fuel because they need to throw something backwards to provide momentum.

 

As for lifting a rocket partway with a balloon/blimp, I used to think that was a great idea and wondered why people didn't do it. Then someone calculated the energy savings, and it turned out to be pathetically small. But some companies are using air-breathing engines to get their craft partway there, so maybe there's something to that.

[Zolar V]

I am afraid you misunderstand, the space vehicles themselves are not of a design that incorporates nuclear power or a fan system. Rather the hovering/floating launchpad is. at 30,000 ft there is sufficient air to allow for such a system to proceed. Hence why we have common commercial flight using jet engines at cruise altitude at such an elevation. I't isn't until 45,000 to 60,000 ft that the air becomes much to thin to support such forms of thrust generating designs.

 

http://www.engineeringtoolbox.com/standard-atmosphere-d_604.html

Edited December 16, 2010 by Zolar V

[Janus]

I have actually read and have been following both of those projects since their origin. They are in fact, great ideas on getting orbital and sub orbital vehicles into their respective orbit without having to carry so much fuel and be extremely large to accommodate said fuel.

 

 

Yes, i understand that it would be energy inefficient, however the slab of land could act as a floating sub-orbital launchpad for space vehicles. The vehicles themselves not unlike Virgin Galactic's designs would require less energy to escape earths gravitational pull because they would be launching from 30,00-60,000 ft. The floating launchpad though would require a tremendous amount of energy, doesn't need to be highly energy efficient, it only needs to be able to produce a sufficient and stable amount of thrust for a long period of time. Such as it is, regular nuclear reactors with a bit of a different design for the cooling mechanism could be outfitted to suit this purpose.

 

With the floating launch pad, you could in fact fly material and vehicles via regular cargo planes to it. It would serve as a sort of staging ground and command center to space operations.

 

Launching from such a platform would only reduce the space vehicle's fuel requirements by ~1/2 of a percent, which would be wiped out by the fuel needed to fly the fuel and components to the platform. Whereas putting the same resources needed to build, maintain and keep aloft such a platform to increasing the exhaust velocity of the spacecraft by that same 0.5% will decrease your fuel needs by 0.8%. A much better payoff especially considering it wouldn't involve a nuclear reactor floating overhead.

[D H]

The potential savings are a lot more than 1/2 percent. The rocket equations says that making a payload go even a little bit faster at engine cutoff can require a lot more fuel. There is a flip side to this: Anything you do to reduce the impact of the initial launch conditions has a huge payoff in final velocity. Increasing launch altitude has two big benefits. One is the obvious but small decrease in energy needed to get something into orbit. Not so obvious is that the rocket is no longer plowing a hole through the thickest part of the atmosphere. Also not so obvious, rockets are more efficient in vacuum as opposed to at pressure. All other things being equal, these apparently small gains becomes a much bigger gain in terms of payload mass to orbit.

 

This is not a new idea. To the contrary, it is a rather old idea that has largely been abandoned. How old? The first successful rockoon (google that term) launch was in 1953. So, given the advantages, why has it been largely abandoned? There are huge issues with range safety. Range safety is the #1 rule in rocketry. When things go wrong, and they eventually will, your rocket had better not crash into a town full of people. There are huge problems with safety aloft. Look at what happened to SeaLaunch about four years ago. Finally, there are huge, huge problems with economies of scale. As a rule, small lift systems cost more per unit of mass than do medium lift systems, which in turn cost more per unit of mass than do heavy lift systems. It is only with ultra-heavy lift systems where diseconomies of scale start kicking in.

 

Sans hand-waving science fiction, it is very, very hard to take advantage of these economies of scale with balloon or jet launched rockets.

[Zolar V]

mmmm interesting reads.

 

Other than politics and minimal safety concerns, where there any other legitimate reasons why those such projects were thwarted?

[D H]

What political concerns? I didn't raise any.

[JohnB]

Since a launch to space is mostly about speed, I've never understood why we still go straight up.

 

Why not lie the sucker on its side and use a mountainside as a ski jump? (A la George Pals "When worlds Collide".) I would think that a Shuttle would be going a lot faster if it wasn't wasting fuel to lift fuel.

 

Or is it that Mach 6 bird strikes made the idea untenable?

[insane_alien]

Since a launch to space is mostly about speed, I've never understood why we still go straight up.

 

Why not lie the sucker on its side and use a mountainside as a ski jump? (A la George Pals "When worlds Collide".) I would think that a Shuttle would be going a lot faster if it wasn't wasting fuel to lift fuel.

 

Or is it that Mach 6 bird strikes made the idea untenable?

 

its because of how thick the atmosphere is. the less vertical speed you have (by pumping some of the acceleration into horizontal vectors) the longer you stay in a high drag environment.

 

anything below about 10km you should be focusing on mainly going straight up.

 

launches do tend to start tilting over quite soon after launch at the optimum rate.

[D H]

Since a launch to space is mostly about speed, I've never understood why we still go straight up.

The optimal orientation at launch is pitched down a bit from vertical, pointed at the right compass angle (north, east, etc) so that the vehicle will end up in the desired orbit, and for asymmetric vehicles, in the roll attitude that minimizes stresses on the vehicle, particularly at max Q.

 

None of these conditions are true for the Shuttle's launch orientation. Having a vehicle in the optimal orientation at launch for getting into orbit typically is not a driving concern. In the case of the Shuttle, and in most vehicles, it is far easier to put the vehicle in the proper orientation after launch instead of doing so before launch. The driving concerns for the launch orientation are stability of the launch stack, lack of undue stresses on the vehicle and on launch tower, directional constraints placed by the launch tower, and constraints due to the mechanisms used to move the vehicle to the launch tower. The Shuttle, for example, launches in its particular orientation because the Shuttle program is reusing capabilities initially built for the Apollo program.