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Design of Next-Gen NASA Rocket Showing Flaws
caffiend666 writes "According to an AP news article, NASA engineers are concerned about the design for the new rocket meant to replace the shuttle. Work on the project has revealed that the first few minutes of flight could see 'violent shaking', a serious flaw that might destroy the craft soon after launch. 'NASA officials hope to have a plan for fixing the design as early as March, and they do not expect it to delay the goal of returning astronauts to the moon by 2020. The shaking problem, which is common to solid rocket boosters, involves pulses of added acceleration caused by gas vortices in the rocket similar to the wake that develops behind a fast-moving boat.'
...before it's built. Seems like a non-story.
so they found a problem with a preliminary design. big deal. that's why they call it research and development.
how long did it take to design the saturn Ib/saturn V and make sure that they'd mate well with the apollo capsule? how long did it take to come up with skylab, an orbiting lab that could be mounted on a saturn V?
i expect it'll take about five to six years to bring the orion program to a complete first generation system.
when religion is no longer the opiate of the masses, governments will resort to real opiates.
You mean they didn't get the design of a prototype exactly right on the first try? Amateurs! Seriously though, where is the news here?
today is spelling optional day.
If anyone else has read Diane Vaughan's Challenger Launch Decision, he or she will know that launch schedule pressure from upper management was a leading cause of the rationalization of risk that NASA undertook to justify flying with known Shuttle desgign flaws. Hopefully, in this case, the NASA senior managers are not applying the same mindless schedule pressures that leads to quick fixes and mindless workarounds at the expense of long term safety.
We all know what to do, but we don't know how to get re-elected once we have done it
How is it that astronauts managed to land on the moon in 1969 but the next mission to get people to the moon will take until 2020? With today's engineering tech - CFD software, advanced materials science, VR simulation, rapid prototyping technology - and lots of commercial sattelites shot into space every year, it should be much easier to get people to the moon and back safely than it must have been in the 60s. Unless of course that landing was faked as some people allege.
It's a harmonic vibration issue apparently, and these are generally solved quite easily. Adding or removing stiffness, a spiral wrap of an energy dissipating elastomer, isolation mounts, ading or removing mass (or simply moving mass around)... doesn't look like it's a severe issue at this early of the design stage. Someone's just being alarmist.
She can't hold much longer, captain!
Management....wants....a....launch....so....shut....the....fuck....up, Scotty!
Table-ized A.I.
Actually, NASA's ROI is pretty good at about $7 returned for every $1 spent. They also develop a lot of technology that doesn't have a financial ROI, but rather a simple non-tangible benefit to society as a whole. For example, they developed the CCD imager for use in the Hubble Telescope. That technology is now widely used in inexpensive digital cameras but is more importantly also used in medical imagers for detecting breast cancer. It has eliminated something like a half a million unneeded biopsies which not only save that cost, but also the pain from the procedure itself.
Bill
It's my Sig and you can't have it. Mine! All Mine!
This was brought up last NASA story. Somebody pointed out that just ONE of the technologies produced for the Hubble telescope lead to more money saved on machines scanning for breast cancer than it cost for the Hubble in its entirety, and that's just the price tag, not the lives that have been saved because of that alone.
When stationary, the air must have a net velocity in excess of 400 mph for the engine to retain efficiency - which a turbine can easily do if there are no other complications. Eventually, the turbine gets in the way, hence the need for a really good bypass system. White Knight avoided the need for TAR by having the first stage as an actual aircraft, but a conventional aircraft isn't going to be capable of carrying the weight needed for true orbital flight, let alone interplanetary flight. Affordable space flight is probably going to require TAR engines.
(Other alternative launch-assist methods include using linear accelerators - basically strap the rocket onto something akin to a bullet train and then get the train up to the critical speed, or using a very powerful gas cannon to fire the rocket into the air at the critical speed. The first would likely end up more expensive to operate than a TAR, the latter would require a very sophisticated multi-charge arrangement if it is to avoid killing everyone onboard, but might end up being another viable method.)
One thing I think can be said for certain - by 2020, no sane engineer will be designing launch vehicles for space that use a rocket first stage. I'll give it a 40/60 chance that by 2020 commercial space flight will have surpassed NASA in terms of cost-per-unit-mass-launched, and 20/80 that hobbyist space flight will have done likewise. If NASA persists in long-outmoded next-gen launch vehicles, then somewhere in the 2030-2050 timeline, NASA will be redundant. Government-run organizations make sense for bleeding-edge work because that is generally too expensive for everyone else. However, once everyone passes said Government agency's technology, it has no value or merit. To have value for money, NASA should be working on systems that will become bleeding-edge in 2020, not what were bleeding-edge in 1920. R&D is the expensive work, everything else is meccano tech.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Seriously, this was known about forty years ago and are called pogo oscillations. They are generally disastrous, and they were the cause of Apollo 13's fifth engine shut down after liftoff.
In general, I'm pretty non-plussed by NASA's moon landing attempts. Their design is basically Apollo rehashed plus forty years (fifty years if it actually launches - pretty depressing), the vast majority of it isn't reusable (I haven't got a clue how they can call it a shuttle replacement) and it really doesn't get us any further forwards in terms of making getting into space easier, safer and something that can be done on a regular basis.
Saturn V multi-engine pogo effects were solved by buffering the fuel supply with super-critical helium cells and adjusting the guidance system for smoother steering impulses.
A single solid propellant pogo on the other hand, is more complicated due to fact that you have variances in the solid, no matter how precise the mix is. The Japanese have been tangling with this for some time with success and failures, more failures are recorded though. Go with a clustered booster kit, then would be able to counter most of the pogo with each booster's own vibration frequency.
A Delta-Style cluster kit would resolve this problem and give a higher delta-v impulse to the stack as a whole. The ticklish part would be man-rating the stack with the added solids. One solution would be to stagger the cluster's firing as to maximize the dampening effects. This would add a safety factor in case there's a failure in the cluster at any stage, the opposing elements would be jettisoned along with the failed unit. Then the second stage would simply burn longer to make the orbit, or a contingency plan would kick in, with maximum of life safety.
First rule of holes; When in one, stop digging.
http://en.wikipedia.org/wiki/Blue_streak
http://en.wikipedia.org/wiki/Black_Arrow
These rockets were a departure from everything else around, and used Hydrogen Peroxide as an oxidiser - cheap, readily available and works well at normal temperatures and pressure. Most considered the fuel to be too hazardous, and a Hydrogen Peroxide fuelled torpedo allegedly sank the Kursk (probably not sensible on a submarine), but the British developed ways to handle it safely and efficiently. To this day, no one else has tried this method and its pretty advanced rocketry even forty years on. It certainly gets rid of the dangerous handling of liquid oxygen, which has to be kept ultra cool and under controlled cryogenic conditions.
After a textbook final launch, the project was cancelled. Given the need for commercial satellite launches over the past few decades, the mind boggles as to how cheap and useful this could have been if developed further. The British, as per usual, decided that simply reusing the Scout solid fuelled rocket would be cheaper. Go figure.
>they do not expect it to delay the goal of returning astronauts to the moon by 2020.
of course not, what's going to delay going to the moon again by 2020 is the fact that congress has no intention whatsoever of paying for that, and no one, not even Bush takes the program seriously.
Why are they wasting money on programs that are going to be thrown right out the window, never to be heard of again, as soon as the next president takes office?
I wish NASA would put more effort into developing gaseous core nuclear rocket engines. There was a nuclear engine project in the late 60s using a solid core reactor, but gaseous core reactors have not been thoroughly explored. Whereas solid reactors melt above about 3500C, a "light bulb" type of reactor consisting of a hollow quartz bulb with a cloud of gaseous nuclear fuel confined in the center could operate at 25000 C, radiating in the ultraviolet range instead of heat per se. In an engine based on this type of reactor, hydrogen flowing past the outside of the bulb would be superheated and expelled as rocket exhaust. No chemical combustion, no radioactive emissions, just heat transfer.
Check out this interesting article, part 10 of a series, about a hypothetical design for a non-polluting, 100% reusable nuclear rocket based on the Saturn V form factor. Using existing engineering apart from the gaseous core reactor, it could lift 1000 tons of payload into orbit (6 times the capacity of the proposed single-use Ares 5 cargo rocket, and 30 times that of the shuttle), and then return 1000 tons of cargo to a powered vertical landing. No expendable fuel tanks, no solid booster recovery, just a big old Flash Gordon style rocketship. This is heavy lifting power that could take up a space hotel or moon base in one shot. It could power enormous ships to Mars in 3 months, not merely to explore but to colonize, carrying hundreds of people at a time, hundreds of tons of equipment and supplies, and highly effective radiation shielding.
I know it's the "N" word, but this rocket wouldn't be a nuclear disaster waiting to happen. If such a ship crashed or exploded and released its entire nuclear fuel load into the atmosphere, the nuclides released would be 1% of what came out of a single 1950s bomb test (and there were many of those).
LOX is routinely handled by thousands of industrial facilities in the US alone. Its properties are well known and it has been used safely for over a century.
Liquid boosters have been used safely on dozens of rocket types. They have been used safely to launch crewed capsules. Liquid rocket engines are commercially available. (In fact, every single crewed American vehicle has had liquid fuels as their main source of energy. The SRB's on the Shuttle are booster assist and the only Gemini to fly on a solid was an unmanned test capsule).
What we are seeing here is a departure from decades of development. Solids have been considered unsafe for manned flight for decades as they are not able to be throttled in flight. Once lit, they burn to exhaustion. They have uneven burn characteristics due to uneven mixing of the propellants. No solid casing has ever been put in a load of this magnitude. (The SRB's on the Shuttle never carried the full weight of the shuttle and they were axially loaded as opposed to have the load directly along the case). There is no engine shutdown in an SRB.
Arguing that liquids would take a lot of development to get right is a bit misleading as it is just as much a statement to be made for SRB's.
The whole Shuttle-derived stuff is crap. These are essentially new engines along with a new booster design and they should have had a design competition and weigh the relative merits of various design proposals. This was a fiat decision made by Griffin when he came into office. There was no technical justification. No weighing of options. Even the sizing of the Orion is extremely questionable.