Thank you for your answers!I was thinking about transportation between factory in LEO (space station in LEO) and Earth, not other planets (I cannot imagine why we will have a lot of traffic from other planets/Moon soon).Actually, I was trying to find out what types goods can be manufactured in space, which would justify such venture.Surprisingly, I couldn't find any information about how much would be price of kg of something transported from LEO to Earth. It seems that nobody ever made even a paper-spacecraft, designed to bring goods from orbit to surface; spacecraft that is designed to be launched empty (and refueled in orbit if it uses powered landing), and return with cargo.With current launch prices, I guess, only mining gold and platinum from asteroids will close the business case, but if the price can be less than 100$ per kg down, we have more options.
What are advantages and disadvantages of powered landing (future Dragon) and aerodynamic (Space Shuttle, Dream Chaser) landing types?For example, let's assume I have a factory at LEO , and I need to transport product from LEO to Earth, and also to move workers up and down (just a thought experiment).
The first thing to manufacture in space is perhaps spacecraft. After all - they are so valuable that it is worth the cost of launching them to orbit.Steve
As for thought experiment of a factory in space. I am guessing you mean something which doesn't high volume- making drugs or something with low mass but is valuable. So perhaps 10 tons per year shipped to earth per year? With increase possible, perhaps to say 100 tons per year?
If whatever you shipping from space to earth surface can withstand high gees- it's cheaper. 50 gees is a car accident. If payload can withstand over 100 gees, "landing" is more like a controlled crash. A controlled crash into a lake, could something with fairly high terminal velocity. And one major aspect is the accuracy of hitting say 10 sq kilometer area.Normally, one want re-entry which is lifting body- to reduce gees [and heat- though heat isn't as challenging as gee loads].
The first thing to manufacture in space is perhaps spacecraft. After all - they are so valuable that it is worth the cost of launching them to orbit.
One advantage of aerodynamic landing [ from LEO ] is that it has actually been done before.
I wouldn't call what Soyuz does a powered landing. The solid retrorockets fire only a metre above the ground. It's more an impact attenuation device like an air bag. (And its failure means a very hard but not fatal landing.) A powered landing would be something like DC-X or the Masten or Armadillo vehicles. And savuporo is right: that kind of manned landing hasn't been done yet.
I wonder what the trade of propulsive vs autogyro (with and without tip rockets) would look like these days.
These are interesting links.
As far as rotors are concerned, I believe there was a proposal in the early days of designing Vostok to use deployable rotors to land the capsule. This idea was quickly abandoned in favour of a parachute.
The only serious proposal to use rotors all the way through the atmosphere to landing was Roton. I'll say no more about that: there are posters on this forum with far more knowledge about Roton than me.
The capsule that converts into a lifting body seems like a bad idea. It is needlessly complex both in design and operation. Compare it with the simplicity of the CST-100 or Dream Chaser.
No comment about the "UFO" shape!
Again, very interesting links. (You learn stuff on this forum!)
So I should have said: "the only serious proposal to use rotors all the way through the atmosphere to landing that I know of is Roton."
The use of rotors is very attractive but the engineering challenges to using them to land a spacecraft seem formidable. Do you have the rotors extended in some way through the whole re-entry like Roton, or do you deploy them at low Mach numbers just before landing?I've only glanced at the stuff you linked. Have studies been made where the rotors are exposed to re-entry heating? If you wish to avoid that and deploy the blades just before landing, how mechanically complicated would that be? And how safe would that be compared with ordinary parachutes?
Of course as has been said before the original "question" can be answered quite simply with a simple; "Well, that all depends...." at which point you have to get down into the nitty-gritty of what you WANT out of the design in the first place
Ineresting links, thank you. Sounds very complicated though.
RanulfCQuoteOf course as has been said before the original "question" can be answered quite simply with a simple; "Well, that all depends...." at which point you have to get down into the nitty-gritty of what you WANT out of the design in the first place At the first place I want lowest price for bringing goods from LEO down to Earth surface)