From: vince@offshore.ai (Vincent Cate) Newsgroups: sci.space.tech Subject: Re: CATS Idea... References: NNTP-Posting-Host: 207.42.133.252 Message-ID: <9186edb5.0407080450.4df96c8c@posting.google.com> Daniel Walker wrote in message news:... > As far as I can see, the main problem with this is how the spacecraft is > meant to climb while attached to the tow-rope. As it gets higher, the > atmospheric pressure drops, and so would the lift across its wings. This > requires either larger wings for high-flying craft (e.g. U2 spyplane) or a > higher velocity...but in this case the velocity is fixed by the tow-plane. You could have a mechanism near the spacecraft deploy more and more parafoils (think multi-kite) as it got higher. It is a fun idea to have your propulsion down lower where there is air to push on and have many lightweight kites up really high. If your tow plane is at 50,000 feet, you could get much higher than this. You would want to use Spectra-2000 for the line (unless something better comes out) as this is very strong and light. Above 50,000 feet there is less air, so drag on the line should be less than at sea-level, even though your tow plane is probably moving faster than the wind we would fly kites in on the ground. You probably want to have additional kites along the line to keep the line more straight. Record altitude kite flights used this trick. Just how high you could get is not easy to say. My tether simulator could be made to handle this with some work. It seems like with a many kites you would still not get to even 100,000 feet. By the time you get all the different kites you would need, it seems like a lot of trouble for what you could get. Flying SpaceShipOne seems easier and it can go to well over 300,000 feet. As it is designed SS1 could not even be launched from 100,000 feet, but if it could it would only add about 50,000 feet to SS1's height. Rockets are kind of hard to beat. But this is a fun idea. -- 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