Future concept of shuttles?

[tap_sa]

<font color="yellow">"Are we talking spaceplanes vs capules??"</font><br /><br />If wings are a must then I'd suggest trying to make SSTO with ramjet (preferably scramjet too), then the wings would serve a purpose also during ascent. Problems with this path:<br /><br />Scramjet is still at infancy, couple short test flights (X-43, HyShot). How soon can it be scaled to propel craft big enough to carry additional propellant and rocket engines to make it into orbit?<br /><br />Can combined ramjet/scramjet be made, engine that changes it's internal geometry during the flight?<br /><br />How to accelerate into ramjet initial speed? Using craft's own propulsion or some sort of catapult? Separate turbojet, ramjet and scramjet, no thanks. Horisontal take-off with rockets might work but then you have the undercarriage problem; to support the lift-off weight they have to be very heavy.<br /><br />Is it possible to build a vehicle that is light, strong enough to withstand hypersonic speeds and still has enough room for propellants and payload? AFAIK a scramjet has to plunge at much lower altitude when doing, say, mach 10 than a conventional spacecraft during ascent or re-entry.<br /><br />One remotely possible solution for subsonic propulsion could be the oldest form of jet engine, pulse-jet. Just tweek the variable geometry of ramjet/scramjet to an open canal, cover intake with set of reedvalves, start pumping in fuel and ignite. Noisy as a doomsday trumpet but should give you four figure Isp.

 

[cdr6]

Since we cannot avoid the weight/mass penalty we either have to take it with us, or drop it into the ocean. If we take it with us we avoid having to build a new booster but have to pay to overhaul the puppy between flights (until technology gets sorted out). Which brings up a question before I point at X20 and say build it… What was the maintenance schedule and costs on X-15? (That’s as close to a successful winged reentry vehicle as we’ve gotten) The lifting bodies were only aerodynamic studies and there fore do not apply here. <br /><br />“Man rated” expendables are not going to get cheap any time soon. So that leaves us with fly back boosters, but again there is a weight penalty owing to complexity and wings et al. (This was the area I meant with the comment about old technology.) But, in aerospace vehicle design everything is tradeoffs, depending on the mission of the vehicle. So at some point we have to be willing to say what we want, and live with the cost of it, knowing that an optimum configuration is not really achievable. <br />

 

[mrmorris]

<font color="yellow">" “Man rated” expendables are not going to get cheap any time soon. So that leaves us with fly back boosters..."</font><br /><br />So in one sentence you write off cheap expendables and announce the only <b>conceivable</b> alternative is fly-back boosters? Nope -- I don't buy it. I think that a capsule can be built that can fly on the FalconV. If it's built and can fly for the advertised prices -- it certainly qualifies as 'cheap', and if it's done in the next three years, I'd count that as 'soon'. The recovery method for its first-stage is both an alternative to your FB-booster and one that's much easier to achieve.<br /><br /><font color="yellow">"...but again there is a weight penalty owing to complexity and wings et al. (This was the area I meant with the comment about old technology.)"</font><br /><br />I'm missing the connection here. How exactly were you linking the weight penalty from wings and a shift back to using capsules and a statement about that being a reversion to old technology?<br /><br />

 

[scottb50]

How soon can it be scaled to propel craft big enough to carry additional propellant and rocket engines to make it into orbit.<br /><br />It can't get fast enough to ignite without a B-52 and a rocket, and that's for a very small vehicle. Then it would work for a minute or two.<br /><br />One remotely possible solution for subsonic propulsion could be the oldest form of jet engine, pulse-jet.......<br /><br />All of those jets would only work for a very short time, the idea is to get to orbit quickly, not use different engines. It might look pretty impressive as it sheds engines as it climbs. <br /><br />Either way you have to have solid boosters, no matter what to get any sizable payload into orbit anyway.<br /><br /> I hear the Delta boosters are big collectors items, or biohazards or something when they are found. <br /><br />And then Willy Coyote bits the humans if they try to touch the controls? The noise would be awsome, but 4 figure? <div class="Discussion_UserSignature"> </div>

 

[tap_sa]

<font color="yellow">"It can't get fast enough to ignite without a B-52 and a rocket, and that's for a very small vehicle."</font><br /><br />Yes, that's if you have only a scramjet engine, like in X-43. Combined pulse-/ram-/scramjet would cover everything from about zero to Mach 10+.<br /><br /><font color="yellow">"All of those jets would only work for a very short time, the idea is to get to orbit quickly, not use different engines."</font><br /><br />The idea of airbreathing engines would be to linger in the atmosphere to take maximum possible advantage of it in both altitude and speed. Gravity losses would be much smaller because wings keep you up instead of direct thrust. And that four figure (1000-3000 sec) specific impulse sure helps. But because all this requires a lot of breakthrough engineering and maybe even some unobtainium the practical idea is to use serious thrust to punch quickly through the atmosphere as if it was just a nuisance ... because it is.<br />

 

[space_dreamer]

www.abo.fi/~mlindroo/Space <br /><br />www.abo.fi/~mlindroo/SpaceLVs/Slides/index<br /><br /><br />This link to (some dude called Marcus Lindroos) web site. It’s abit old but it has soooo much info on about space plans from the last 30years. <br /><br />The space LV Slide index will give you all an excellent history recap on what’s been proposed before.<br /><br />I could go on and on about how cool I think his site is but just look and your understand!!<br /><br />

 

[space_dreamer]

www.abo.fi/~mlindroo/Station/Slides<br /><br />This space station slide show is really cool to...

 

[kdavis007]

It should be interesting in what they come out with..