From: vince@offshore.ai (Vincent Cate) Newsgroups: sci.space.tech Subject: Re: Rotovator Ideas and Questions References: NNTP-Posting-Host: 207.42.133.230 alexterrell@yahoo.com (Alex Terrell) wrote in message > I'd like to get some thoughts on Rotovators. Any suggestions / > comments / ideas? I think Space Tethers are a very promising tech for lowering the cost to LEO. > Question 1: Are there any advantages of a Hypersonic Skyhook over a > Rotovator. I think the rotovator has more advantages. You have to be able to climb the non-rotating tether, while a rotating tether can toss you after part of a rotation. It takes a lot of power and time to climb a tether. But the only pracitcal place to get power seems to be solar, which adds to weight. Think about a tether 800 km long and having to climb straight up using solar power. Even at a fraction of a G it is going to take some time. So it does not seem practical to pick up a payload very often with a non-rotating tether. > Question 3. Realistically, how feasible is a Mach 13 Rotovator? Would > it, and a Mach 13 Space Plane (SCRAM or Rocket), be a contender to > replace the shuttle? It is still not clear that a scram-jet can actually work. I wonder about the amount of energy lost breaking up air molecules. We came very close to being able to do lots of good testing with the X-15, but it was cancled after only a mockup scram-jet had flown. Now, 30 years later, we don't have as good a test-bed for a scram-jet as we did back then. But a rocket to half orbital speed is easy. In fact, it is much easier to make a reusable rocket to half orbital speed. Many people have made designs for a "fly back booster" that don't seem to need any magic tech. > Question 4: What would be the optimum orbital inclination? Are there > any advantages of an inclined orbit over an equatorial orbit? With an equatorial orbit you could launch something every orbit. If you don't use equatorial then the Earth turns under you and you don't line up with your launch site. > Question 5: If such a Rotovator were to be built, then in addition to > the cable, there would need to be an anchor mass. Could Space Shuttle > external tanks be used for this application? I guess a problem is that > a Rotovator should ideally be in an equatorial orbit, and ETs are > never launched into Equatorial orbit. They would anyway need to be > moved in to a 700km altitude orbit. Changing the orbit of the tank is a big problem. But dealing with NASA is probably even a worse problem. I think it is far more practical to start out with a small ballast and lift small loads at first. This way you can build up your tether using your much cheaper reusable-suborbital rocket. See my spacetethers.com site for a more information and a tether simulator. -- Vince ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Vincent Cate Space Tether Enthusiast vince@offshore.ai http://spacetethers.com/ Anguilla, East Caribbean http://offshore.ai/vince ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You have to take life as it happens, but you should try to make it happen the way you want to take it. - German Proverb