[Kosh]

I just think it's stupid that, rather than developing something new and better, the US is going to throw away the leadership it has had in space exploration for the past 40+ years and go back to some archaic rockets that aren't nearly as versatile as the shuttle is.

I'm sure I'm going to get burned for this but before the shuttle lovers start flaming me let me just say first that I personally loved the shuttle. Having said that, and after putting the emotional component aside, the shuttle wasn't really all that reusable while being practical about it. First of all the "archaic" rockets were still needed to get it into orbit. Secondly after a mission you had to replace half the ship if you ever wanted it used again. In the end it's actually more cost effective to put a soyuz capsule on top of a rocket than strapping a shuttle to two boosters and then have it be a money sink so you can showcase your "reusable" space plane around. It's a matter of practicality - the shuttle still had to burn a bunch of chemical propellant to reach orbit just like any old rocket does. It still cost insane amounts of money to get any usable amount of payload into orbit and the fact you needed to put a lot of money to reuse the shuttle again didn't help.
Don't get me wrong I was sad when they announced it's retirement and I personally thought it performed admirably despite all I just said. Yes, it had two fatal accidents but it also had 30 years of service behind it.

The two main limiting factors with the shuttle besides the safety problems was 1.) the external fuel tank's manufacturing capability was only about 2 per month iirc, so at best that's the number of shuttles that could be launched each month and 2.) maintainence was a real *****, it took a brigade's worth of workers to just to keep one of them flying and even then the turnaround times are usually almost a full month. At that rate it would never bring launch costs down to a reasonable level, which is exactly what happened. Fortunately the Skylon takes these issues into account by being less like a rocket and more like an airplane.

[General Battuta]

The Shuttle was stupid for exactly the reasons described here - all the external paraphernalia that either had to be recovered and prepped or simply rebuilt. It was an ugly compromise. If this thing actually gets off the ground its one-piece design could be what we need.

[Colonol Dekker]

Are there any pics of this cylon skylon thing?

[Kosh]

The Shuttle was stupid for exactly the reasons described here - all the external paraphernalia that either had to be recovered and prepped or simply rebuilt. It was an ugly compromise. If this thing actually gets off the ground its one-piece design could be what we need.

Indeed. The interesting thing with this is going to be its maintainence requirements. Overall they certainly seem lower, although most likely the engines are what will require the most maintainence compared with the body, although since they are mounted in pods I wonder if it would be possible to just exchange them with newer ones to allow the plane to keep flying while engine maintainence is being done.......

[Mustang19]

Score one for sounded cool at the time space projects which end up having extremely limited commercial application wasting my tax dollars once more!

[Thaeris]

I'm certain it's been noted already, but the Shuttle was a necessary system with respect to production and technical implementation in its own time. Obsolete now? Definitely. But realize you're bashing a 30 year old space plane. The argument that "other old flight systems which are of a similar age or older still function well, yet..." doesn't apply, as space flight is still a very immature field in aerospace. The Shuttle, again, was necessary for the evolution of spaceflight.

Now, were there better design solutions available? I think so - a lifting body configuration would have been the best configuration for this type of flight system in my opinion. But realize that ANY vertically launched space flight system is going to be inherently inefficient. Basically, if you were going to build a new shuttle today that launched nose-first into the air from the ground, you'd still have boosters and fuel tanks - there's no way around that due to the available conventional propulsion sources. Skylon gets away from this as - imagine that - you've got a new powerplant. Leave the Shuttle out of this.

[redsniper]

Space space, gotta go to space, wanna be in space, SPAAAAAAAAAACE.

[Mikes]

/petition to change the name from Skylon to Cylon. Because having a Cylon Spaceplane would be so frakking cool.

[newman]

I'm certain it's been noted already, but the Shuttle was a necessary system with respect to production and technical implementation in its own time. Obsolete now? Definitely. But realize you're bashing a 30 year old space plane. The argument that "other old flight systems which are of a similar age or older still function well, yet..." doesn't apply, as space flight is still a very immature field in aerospace. The Shuttle, again, was necessary for the evolution of spaceflight.

Nobody's bashing anything. I even said I was sorry to see it go and that it did have a good 30 year service record considering space flight with out tech level is inherently risky. What we were doing is identifying the  shuttle's flaws - mostly inefficiency from a maintenance and financial point of view. The shuttle was cool, did it's job, and it's now time for it to honorably retire.

[Thaeris]

Fair enough, though I wasn't aiming anything at you in particular. I suppose I presumed another "teh shuttle is terribad" rant was on the way. Such would be quite unwarranted in this thread.

[Kosh]

I'm certain it's been noted already, but the Shuttle was a necessary system with respect to production and technical implementation in its own time. Obsolete now? Definitely. But realize you're bashing a 30 year old space plane. The argument that "other old flight systems which are of a similar age or older still function well, yet..." doesn't apply, as space flight is still a very immature field in aerospace. The Shuttle, again, was necessary for the evolution of spaceflight.

Now, were there better design solutions available? I think so - a lifting body configuration would have been the best configuration for this type of flight system in my opinion. But realize that ANY vertically launched space flight system is going to be inherently inefficient. Basically, if you were going to build a new shuttle today that launched nose-first into the air from the ground, you'd still have boosters and fuel tanks - there's no way around that due to the available conventional propulsion sources. Skylon gets away from this as - imagine that - you've got a new powerplant. Leave the Shuttle out of this.

The biggest problem with the shuttle was the Air Force's meddling with the project, forcing costly redesigns that ultimately forced the program to make major, critical compromises to the finished product that resulted in the various issues that it had. It isn't that the skylon has better technology, it's that the space shuttle could have been done much better than it actually was even using that era's tech level.

[Thaeris]

*snip

* Thaeris facepalms...

Yeah, that was the kind of thing I was trying to steer away from.

Now, if Skylon works, it will ideally give spaceplanes the powerplant they need for simple ground-orbit operations, if such operations can ever be called simple. The weight you can cut from a design by reducing the number of engine types employed is just wonderful. I do need to read up more on the SABRE though, as I'm uncertain if it's cleared to burn a different fuel type in the atmosphere rather than just one of the reactants (presumably liquid hydrogen). Burning a different fuel type while in the atmosphere would have the sole advantage of helping to deny the possibility of burning too much of one of the reactants while engaged in atmospheric flight. Mechanically and logistically, it doesn't make much sense, though. Furthermore, being unmanned and designed for orbital flight, the flight pattern undoubtably will have very tight operational tolerances. Thus, I'm not sure why multiple fuel types beyond the two reactants ever entered my mind...

[Nuke]

seems to run entirely on liquid hydrogen, mixed with either hypercooled air (atmospheric mode) or liquid o2 (low/zero atmosphere mode) as oxidizer. the cutaway on the skylon wikipedia entry seems to indicate an auxiliary propellant tank, which i assume is for rcs and oms equivalent systems. though there is some indication that the vehicle is capable of powered descent, which would require in-space refueling (or a surplus fuel supply left over from launch), though it is designed primarily for an unpowered descent.

i dont think changing fuel type at different launch phases does much to improve efficiency. and generally having a different supply for each stage is not necessary. fuel usage would no doubt be planned for ahead of time. each phase of flight would have its fuel budget, and exceeding that budget would at worst cause an abort, and at best can be worked around. the whole point of staging (aside from removing dead weight) is that you have an engine bell that is suited for the atmospheric conditions during that phase of flight. close to the ground you want a more focused plume but in space you are better off scattering the plume. this engine seems to use an expansion-deflection nozzle, which is capable of changing the thrust configuration based on atmospheric pressure. the sabre engine is meant to be able to function at all stages of flight and do it well.

do read the wikipedia article on sabre, its a good read and it just makes the engine seem badass.
also heres a video for people who are too lazy to read.

[Thaeris]

Thanks Nuke.

I will say that I think the internal grouping about the compressor and main rocket engine assemblies will simplify and streamline as development continues - right now everything looks slightly messy. But then, engines aren't my primary region of expertice.

By the way, for anyone who plays with X-Plane from time to time, there is a Skylon model out there...