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More New Details on NASA's CEV Launcher Studies
TheEqualizer writes "Continuing on the NYT story on NASA's current CEV launcher plans, spaceref has an even
more extensive look with detailed assessments of the available options. By all accounts, it looks like NASA is picking up where it left off with Apollo but also combining it with established Shuttle technology -- the capsule concept of the 1960s atop the shuttle boosters of the 1970s being the winning combination under the current budgetary limitations. However, is this coupling of
old technology and designs really the best we can do?"
Apparently, s/he misunderstands how aerospace technology works: you stay with things that work and improve upon those things that have been problems in the past.
For example: When Wehrner Von Braun and his team set out to design the Saturn V, Boeig was tasked with building the most difficult part, the first stage, or S1-C.
Did they use new technology? In some cases, yes. For the rocket engines, no. The F-1 engines were actually initially designed by the Air Force in the mid 1950's. Boeing instead took the basic design of the F-1, improved it with better construction techniques, better materials and of course, new tubo-pumps, but nonetheless, the basic design of the F-1 stayed what it was.
Later, the S1-C flew flawlessly on every launch but one: on Apollo 6, there was a problem with "pogo-ing," which is a severe reverberation along the axis of the rocket. At that point, they re-studied the issue and re-engineered the ignitors of the engines, and the S1-C was the most impressive weight-lifter in human history from there on.
That's a for example. In the Shuttle design, there is a lot of work on rocket design and implementation that would be crazy to throw away, not to mention extremely expensive to engineer. These are man-rated vehicles, and there, NASA is exceptionally conservative -- they will stay with they know works and create replacements for that they know does not.
This in not building a new computer CPU, or engineering a new product that a failure is tolerable. I would be very surprised and actually disappointed in NASA and their contractors if they were to toss out the baby with the bathwater, and am personally relieved that they are not.
To alleviate the problem, the Orion team proposed a hybrid solution - use Saturn-class chemical rockets to launch an Orion booster. They figured they could build an Orion-class ship that weighed around 150 tons, well within Saturn's ability to loft 400 tons.
NASA's current proposal takes us back to being able to re-consider Orion. What killed the idea was NASA's aversion to risk. There wasn't any appetite for developing a rocket engine that could only be fully tested in space.
The idea of using nukes for Earth launch never completed died. Ted Taylor, one of the Orion team members, figured he could design a nuclear bomb that didn't emit any radiation at all. Ironically, the neutron bomb was an outgrowth of his work.
To me, that's the problem.
The shuttle should have been a step towards true spaceplanes. It wasn't efficient, but it explored our prospects for fully reusable launch vehicles.
The next step was to be real spaceplanes. After that we could begin talking about things like commercial spaceliners, orbiting manufacturing facilities and all the other sci-fi dreams of my childhood.
Instead, we're finding that we can't (or won't: $$$) build on what we learned with the shuttle to create spaceplanes, so we're going back to rockets.
We went from sails to steam-driven paddleboats (which worked poorly) to propeller-driven steamships (which worked really well). The shuttle program is equivalent to saying "These paddleboats just have no future. Let's go back to sails."
Life is short: void the warranty.
I'm so tired of people pulling Burt Rutan out of their ass every time a conversation about the shuttle comes up. It was a great achievement, but it didn't acheive LEO, has NO cargo capicity, and if by "built in his garage" you mean "built by a team of engineers for millions of dollars", well, cool. We got more done in the 60's with this kind of tech than we do now with our aging shuttle fleet. Also, since the boosters and fuel tanks are based on teh shuttles, we can utilize our current network of contractors to supply parts. I'm tired of spending billions just to get into space. Wouldn't you rather take the cheap way and then use the money to build a ship that goes elsewhere (re: Mars)?
"Nobody owns the fucking words man." - James Dean
The shuttle program is equivalent to saying "These paddleboats just have no future. Let's go back to sails."
I'd rather say that the space shuttle is like a paddleboat before the steam engine was invented. Perhaps it's a good idea, perhaps not, but without a steam engine to turn those paddles there's not much point in it. Sailing usually beats muscle power (rowing or turning the paddles by hand).
The hard things in space flight at our current technology level is getting to orbit and reentry. Putting wings on a space craft is optimizing for the wrong problem. As can be seen by the fact that with a "traditional" capsule on top design the astronauts would have survived a Challenger style accident, and the Columbia accident would never have happened.
I think here we're seeing the tension between development and production.
The shuttle has been a decent way to learn about the problems faced by reusable vehicles of a particular type. I'm glad that we did it, and that we have it. Yes, the next step, from a development standpoint, is to take what we learned and figure out how to do it more and better.
But meanwhile we have actual business in space and we need a way to get there and back again. We don't need it twenty years from now; we need it today. What we have today is (a) shuttles with a number of known problems (see above), and (b) big honkin' rockets with three decades of experience in interplanetary travel. Which can we have ready to go by next month? A design that's just been grounded again after two years of fixing, or a design that Just Works? Remember that it's for today, not next decade; we have plenty of time to work up something better for the twenty-teens and beyond.
We need *both* programs to keep the pipeline full today *and* tomorrow. Declaring a single winner sacrifices either today or tomorrow. I'm greedy: I want both.
.. space planes? Take off and land just like an airplane. Whatever happened to that idea?
The unforgiving results of the rocket equation when applied to the orbital velocity (as determined by the Earth's mass and radius) and the chemical energy available per lb of propellant. They all combine to make the task just barely possible. You get the impression that that some god wanted us to be able to get to space - but that it should be a serious challenge.
When your spacecraft must be made almost entirely of propellant it wants to be as close as possible to a sphere: lots of internal volume for propellant, minimum weight of the enclosing envelope. Airplanes really don't want to be anything like a sphere. They like un-spherelike protrusions known as wings. These weigh a lot, especially when you need to cover that much surface area with a heavy thermal protection system.
Landing with wings or lifting bodies can make sense in some circumstances but taking off with wings is ridiculous. The weight of the spacecraft at launch is much higher. If you size your wings for take-off weight you will pay the penalty of those big wings all the way to orbit and back (if it can even make it to orbit).
Just because the idea is intuitively appealing doesn't mean that it makes sense from an engineering point of view.
Weight happens.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
Looking back over the past 30 years, you can make the case that the single largest problem in the STS program, was building it in a side-mount configuration. There were a whole slew of things done that, in hindsight, were stupid, delta planform vs. lifting body, etc. The shuttle design was predicated on the assumption that it was going to become a 100% reusable system once launches were underway, and they could stop throwing away the ET.
But it taught us a whole lot about how *NOT* to build a reusable spacecraft. Someday, maybe we'll end up building two-stage reusuable craft like the Shuttle was originally envisioned to be. Someday when we have money, will, and a reason to launch 100 flights per year.
Until that day, rather than sit down and reinvent the whole thing from scratch and fail (X33), they build a smaller incremental change using existing hardware. Maybe someday we go back to lifting bodies strapped to the ET's nose. Maybe those boosters (SRB) get airbreathing assists and flyback capability. Who knows. I'm certainly happy with this decision to reuse existing hardware.
they would declassify their UFO-captured technology, we could be zipping around the solar system by now for pretty cheap!
They are also attached to launch at a specific location and need yanked out of florida!
There are a number of factors to consider when launching a rocket and Florida provides the best launch location for the US. Here are the factors to consider...
- You have to launch east so you get the added help of the rotational velocity of the Earth.
- You want to launch over unpopulated areas (the ocean is pretty unpopulated for a long way). The Russians use the giant desert in their southern regions for this but don't care as much about the people living under the launch path (have you seen the pictures of rocket debris in Russian villages?). The Europeans also use the ocean (from French Guiana)
- You want to launch from the lowest possible latitute because you can only reach higher latitude orbits in one go (you can reach any orbit from the equator but you can't reach an equatorial orbit from the tropic of cancer without changing orbit in space)
- The ideal US launch facility from a physics standpoint would be Hawaii but the cost of getting the vehicle to Hawaii would be insane so we opt for a higher latitude, continental launch facility).
"As for Rutan, he hasn't demonstrated the ability to do anything but..."
The ability to fly an airplane around the world on one tank of gas for the first time in history....
and
He led the first private company to get a person in to what is technically defined as space.
The key point about the second one is he was working to a clearly defined objective set by someone else, he achieved that objective pretty much on time and on budget. If someone had set the target to 100 miles he would have done that. If someone sets the target to LEO, with a suitably large prize, and he can get the funding I'm willing to bet he will do that too.
You see Rutan has some redeeming qualities Rutan that are organizationally absent in NASA:
- he is a pragmatist
- he can work on a budget and stay in it
- he can work on a schedule and stay in it
- he sets obtainable and worthwhile goals
- he achieves the goals he sets out to obtain
NASA's manned space program has been failing on all five counts for pretty much the last 30 years, something approach a working lifetime. In particular that can't seem to achieve their goals which is the most damning thing you can say about them. Either the goals are bad, which they have been, and they have been impotent in setting goals that are obtainable and worth obtaining, or there is some element of incompetence there that prevents them from succeeding. There are lots of great and talented people there but the organization as a whole, especially its upper management is disfunctional. Hopefully Griffin will change that but he is bucking political, bureaucratic and contractor empires that will endeavor to destroy him if he doesn't give them what they want. If he gives them what they want then the organization remains mired in disfunctionality and probably fails. He is in a rock and a hard place job.
All these studies you see now are various political, bureaucratic and contractor empires jockeying for position. In particular there are giant jobs programs based on shuttle hardware and they are DESPERATE to keep all those jobs in tact which is why shuttle derived hardware has a 90% chance of winning.
As long as all this stays on an engineering dialog footing its entirely healthy. If it turns political and inferior solutions are chosen due to the aptitude for political maneuvering of one of the fiefdoms that is when it will turn bad and dangerous. Whenever you see a new proposal, figure out who is producing it and what there current vested interest is and how it biased their conclusion.
@de_machina
> Burt Rutan didn't go into orbit, he got up to 100 kms.
And going _up_ is the easy part; it's going sideways fast enough to orbit that is the tricky part. Energy is proportional to V^2.
(orbital_velocity/spaceshipOne_velocity)^2 =
(17,000mph/2,500mph)^2 =
=46x
So to become orbital, spaceShipOne needs *46*
times more energy, and needs to disipate *46* times more energy for re-entry.
So yes, spaceshipOne is cool and all that, but to say NASA is clueless is wrong.
"The shuttle should have been a step towards true spaceplanes."
Why?
What's the big deal about spaceplanes, anyway? Why are we so in love with them? Is it just because the idea of a VTOL rocket seems dated, like some bad 1950s sci-fi flick?
An airplane is practical because as long as you're moving forward (going someplace) anyway, you might as well generate lift with all that air you're flying through. It's the simplest, easiest, cheapest way to the solve the problem.
On the STS, I believe the wings don't do anything during launch (except act as targets for debris, apparently). Even if you take off like an airplane, wings loose effectiveness way before you get to space. Once you're in space, they obviously don't do anything. Coming back down is the only time they come into play, and they're not terribly impressive then. STS airflight isn't so much "gliding" as it is "falling out of the sky, gently".
What's the practical benefit of wings on a spacecraft?
dragonhawk@iname.microsoft.com
I do not like Microsoft. Remove them from my email address.
The reason people keep mentioning him is that NASA failed to develop a comparable technology with multi-billion dollar budget. Even as it is, it's useful for a number of things - Let's compare: training astronauts The Vomit Comet letting lay-people see space Is this a role NASA should be fulfilling? taking one-time measurements with high-altitude scientific instruments that are not worth launching a permanent satellite. We have this technology already: rockets. No need to risk humans, and it's a hell of a lot less engineering. If scaled composites had a decent budget, I am sure they would come up with at least a one-way unmanned orbit vehicle in a relatively short time - then they just need more fuel, no heat shielding. We have several one-way, unmanned orbit vehicles: a plethora of rockets. Private companies have been using them for years to get things into orbit. Scaled Composite's work is ground breaking mostly because it's a crew vehicle developed in the private sector; that's never been done before. But it's not a drop in replacement for the shuttle. Period. End of story.
"Nobody owns the fucking words man." - James Dean
I remember in high school a younger neighbor of mine got a GI Joe space shuttle. It was a lifting body with a rocket powered and MANNED booster stage. It was not a jet, but it was a liquid fueled space craft on it's own (well, it looked like it was). Anyway, I always thought why did they not build something like that instead of the current design? Anyway, I think the plane format has merit as soon as we figure out how to make more compact and efficient rocket engines. Launching a current Shuttle from the 747 carry is not a option since the SSME's lack tankage. If they figured out how to make engines with equivalent thrust to the SSME's without the massive fuel requirements, it could work.
The big push to the capsule format again is a good thing and let's remember one thing.....it could be the size of the Apollo capsule, but they would now have more room since modern electronics are MUCH smaller then the old technology used in Apollo. The new capsules does not mean that NASA is switching back to nixie tube displays and old style avionics. The new capsules could even be BIGGER. I thing the problem the shuttle brewed was it stagnated aerospace development because the government did not invest in new vehicles and had not since the shuttle came into use. Now with Xprize in the can(which I might add brought a TON of new ideas to the plate) and intrest in the space program building, there's reasons to go into Aerospace and new materials development with the eye on new space vehicles. As the entire NASA budget is only 2 percent of our total federal budget(they SHOULD raise this!), I personally would love to see the era of the 60's - 80's return to the Aerospace industry.
Gorkman
107 Shuttle flights, 17 Apollo with 7 attempts to the moon (6 successes). In flight Apollo deaths Zero, (according to my count) in flight Shuttle Deaths, 13 (also according to my count).
NASA has a history of fixing known problems, and not putting Astronauts into the vehicles if the problems are known to possibly cause death. They've spent 2 years fixing the last discovered problem and it still exists.
I don't see what the big deal is. They're talking about using the rocket technology which they already have and mixing it with shuttle technology which they also already have. Where's the harm in that?
/* oops I accidentally made a comment, sorry */
I remember in high school a younger neighbor of mine got a GI Joe space shuttle. It was a lifting body with a rocket powered and MANNED booster stage. It was not a jet, but it was a liquid fueled space craft on it's own (well, it looked like it was). Anyway, I always thought why did they not build something like that instead of the current design?
I think I have seen some drawings of some booster stage with flyback capability. With todays electronics, there's no need to have it manned though. But anyway, the problem it that the wings add weight. It's just cheaper to put parachutes on the boosters and pick them up where they land.
Anyway, I think the plane format has merit as soon as we figure out how to make more compact and efficient rocket engines.
Rocket engines are plenty compact and efficient already. The problem is that there is only so much thrust you get from chemical fuels. We're already pretty near the limit. Nuclear might be an option, but suffers from political problems.
If they figured out how to make engines with equivalent thrust to the SSME's without the massive fuel requirements, it could work.
Um well, if they could get that to work pretty much any sci-fi scheme would work too. With chemical fuels it won't happen.
Errrrr..... you seem to be thinking they will be 'landing' in the sense of sitting down on gear gracefully. They go back to capsules then they are going to go back to parrachutes and splashdowns... or possibly go with a solid earth landing like the russians whcih is essentially just a crash with shock absorbing seats for the occupants. They may dig up the old Idea of doing a parasail instead of a simple drouge parachute and actually doing a kind of glide landing like a skydiver might... but the control system for managing the airfoil was always a bitch in that scenario.
I can't help but think there has to be an air breathing way to do the SRB's... though if you can't shave any weight in the process of providing the same power it is essentially just a lot of work for no gain... unless the safety margian is greater.... a fly back and fast turnaround would make it worth it though.
I don't ask you to be me. I only ask you not expect me to be you.
To make a reliable two-stage reusable launcher, the first stage has to achieve some nasty speeds and some serious height (say Mach-3-6, 30-50km).
Who says?
Len Cormier is working on a very realistic concept where the first stage will climb to around 30 km but will do so at subsonic speeds. It will have a very large wing area compared to its weight to be able to generate lift at such low speed and thin air. The wings will be a fabric-covered frame and the whole thing will look more-or-less like a giant ultralight. Unlike conventional aircraft which are optimized for cruising at maximum fuel efficiency this thing is designed to be simple and climb rapidly. It turns out that the best engine for it is a rocket because of its high thrust to weight ratio and ability to work efficiently at high altitude. Yes, a subsonic rocket-powered giant hang glider. It sounds weird but it makes perfect sense from an engineering point of view and is pretty low tech in comparison to spacecraft and conventional aircraft.
The second stage can use efficient high expansion ratio engines that can't work at sea level. The second stage does not need to suffer a rough and fast ride through the dense atmosphere (max Q). A short and chubby body can be used, which is much better for containing large amounts of fuel in a lightweight envelope than a skinny cylinder. A large empty tub also has a much easier time on reentry - temperatures are much lower when the mass divided by cross section is lower, reducing TPS weight and allowing use of materials less fragile and with far lower maintenance than shuttle tiles.
These things make a big difference. Although the second stage needs almost as much performance as a full SSTO it can be much easier to build when it starts at 30km altitude.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.