Slashdot Mirror
NASA Installing Shocks On Ares
caffiend666 writes "In order to abate the massive vibration issues of their new Ares I spacecraft, NASA is installing shock absorbers. 'The plan is to install 16 canisters in the bottom of the rocket with 100-pound weights attached to springs. Battery-powered motors will move the weights up and down to stop vibrations. Those are essentially remote-controlled shock absorbers, said Garry Lyles, who headed the team of NASA engineers tackling the shaking problem.' So, when the spaceship is a rocking, don't come a knocking?"
sounds like the design is a massive failfuck.
Will they then have to haul nearly a ton into space? That sounds like a very costly improvement to the shuttle.
So they're loading down the first stage with at _least_ 1600 pounds of weight (plus motors, plus batteries, plus cannisters) to dampen vibration?
That's pretty crazy, I would think. It's not like all that weight is gonna come free.
...that's 1600lbs that could have been used to lift more fun stuff in to space.
"False hope is why we'll never run out of natural resources!" - Lewis Black
But adding 1600 lbs plus weight of electric motors to the weight of a space craft, seems like a last resort option.
Nothing else worked?
Think Deeply.
That's great. Use a solid rocket to save a couple bucks, then add 1600 pounds of dead weight (not dead, really, but still needed because the solids vibrate too much) to make the thing work.
This Ares thing is getting more shuttle-ish by the minute.
Would the Apollo survivors please come back from retirement? Looks like the new folks are having some trouble with the problems you already solved.
I know the whole Ares thing is to reuse shuttle parts, but it seems that there is very little left from the shuttle that's worth saving and even less that's being saved. The Ares V core is wider, the solids are longer... Couldn't they just build an improved Saturn V and pretend the shuttle never happened?
I bet Kerosene/LOX would be cheaper too.
http://www.dieblinkenlights.com
Chrome rims and a spoiler. We might not be alone, so dress to impress!
Btw, not 16, "a 17th shock absorber will be a ring of weights and springs near the middle of the rocket".
Might not have a cannister though, or a switch ; )
"Kill 'em all and let Root sort 'em out"
Lets review what we have so far:
1. First attempt at building a man rated launcher with an entirely solid fueled stage
2. Largest solid rocket booster ever flown
3. First (I believe) aerodynamically unstable man rated launcher
4. And now, first use of shock absorbers to dampen an otherwise lethal vibration in a launcher
Considering how reverting to capsules was seen as a safe bet, and as taking advantage of existing technology and production lines, there is an increasing amount of experimental new technology involved.
With the Shuttles headed towards retirement and the only remaining source of access to the ISS in jeopardy due to chilly relations with Russia, now doesn't seem like the best time to be getting experimental. Functional will do just nicely.
I honestly think that a manned ATV might fly before Orion at this rate.
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
In related news, did anyone notice the Oprah ad below the story (down on the left side):
"LOSE WEIGHT IN 2008! THE BESTLIFE DIET - JOIN NOW!"
Talk about context-sensitive advertising ;-))
Tell Gus Grissom, Ed White and Roger Chaffee how well the original Apollo design worked for them. Oh wait you can't - they're dead.
No mod points, no meta-moderating/Firehose/all the other free work Slashdot wants me to do.
The US government oversaw Apollo. US enterprise is currently overseeing a crappy suborbital space plane and an even crappier low payload rocket.
If the current incarnation of NASA has a problem, it is that like many modern government agencies it is trying to emulated private enterprise too much.
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
Whilst I'm not overly surprised by the decision why have they left it this late, as its a well documented problem thats been around since the beginning of space flight.
No, they are dampening the vibrations because vibrations from SRBs are too unpredictable to be canceled out in the way you describe.
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
"..their building this thing with not even half the money of the Apollo program.." (sic)
Actually, elegance in engineering doesn't cost any more, and can even be cheaper. What costs more is finding problems half way through a project and then solving them by throwing extra weight and complexity at it. That will cost more money, more time, and, if it creates more critical failure points, more lives....
Please give these guys a call http://www.directlauncher.com/
This sounds like more than the shock absorbers found in your car and other mechanical systems. Those are passive spring-mass-damper systems. These sound like active vibration control systems, that try to cancel out one shaking by producing an equal and opposite shaking. It's fairly straightforward, the sort of thing you can learn in an undergraduate control theory class, but getting it to work robustly, even on a test stand, takes a fair bit of tuning. Getting it to work on a complex system like Ares seems to be asking for trouble.
If nothing else, it's certainly a very heavy fix. My rocket science is a little rusty, but the 1600 lbs of active weight in the first stage probably doesn't translate into 1600 lbs of lost payload (if it were in the crew capsule, then yes, but the first stage doesn't go all the way to orbit). Even so, it's some lost payload capacity, and does nothing to tackle the root cause of the problem. Back to the drawing board, guys!
Yeah, where do you find living Nazi-Era German Rocket Scientists these days?
Tsukasa: All I really want, is to be left alone...
The flammable Apollo Command module was designed by North American Aviation, not by the imported German rocket scientists who worked on the Saturn V booster.
(The Apollo capsule was considered by many to be bloated and technically inferior to the earlier Gemini capsules.)
Their demise wasn't caused by a flaw in the rocket itself, it was because the capsule was using pure oxygen under low pressure in order to save weight.
Unfortunately - materials that were flame-retardant or flameproof in normal air became extremely volatile in the 100% oxygen atmosphere in the capsule. They changed to a different mixture after that accident.
Their accident also happened while on the ground during a test and not in space. Their accident was actually to honor them being designated Apollo 1. (as from what I have understood from at least one source, other sources does claim that it already was designated Apollo 1). So the only in flight accident with the Apollo program was Apollo 13 - and they did survive.
So this actually tells us - beware us from accountants.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
You forgot "plus the additional fuel needed to haul that 1600 pounds skyward".
That's the bitch about designing spaceships - for every ounce you add, you need at least an additional half-pound of fuel* to shove it upwards.
* depending of course on such details as specific impulse, fuel density, etc etc.
Quo usque tandem abutere, Nimbus, patientia nostra?
Ever get the feeling they're building a kludge all over again? Space Shuttle II -- Revenge of Thousands of Glued On Tiles and Strapping It to the Side an Ice-Covered Tank.
There was no way to passively dampen the vibrations? A simpler, cheaper solution? So instead they'll introduce another ton of lift weight and 17 additional motors and batteries to fail.
My prediction: in the first 50 launches this system will fail and the rocket will either shake the astronauts and payload apart (failure to dampen) or spectacularly shake the rocket apart (oscillate lopsidedly or out of synch with the vibrations).
With luck Slashdot will archive this long enough. Given that this is a NASA project, that might not be likely.
Get off my lawn.
There's a much more informative article on Space.com from yesterday: http://www.space.com/news/080819-nasa-ares1-vibration-update.html
It's like trying to reduce the vibrations in your Chevette by encasing it in lead: probably effective, but your gas mileage is going to suck.
Not going to talk about your "Germans" comment, but...
Apollo had at least 2 major incidents, killing 3 astronauts, and endangering 3 others.
Shit happens when you are pushing the envelop. Mercury, Gemini, Apollo, Shuttle, Salyut, Soyuz, Mir, all had their fatal or near fatal incidents.
And each have/had "inelegant design flaws".
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
Fly EELV instead - make Orion a much simpler and more robust capsule. Delta IV Heavy can already lift the ISS-bound version of Orion without trouble. Ares is a joke, a joke played by ATK, Mike Griffin and Scotty Horowitz on the US taxpayer.
The other problem with ESAS/Ares/VSE as currently implemented by NASA is that they choose the launcher (vaporware Ares based on SRBs) and are trying to shoe-horn the payload into it. This is 100% backwards from how most missions are designed, with the payload dictating the launcher.
Between this and the trouble that Orion development is experiencing, it would appear that the Chinese or even US private firms will be on the Moon before NASA. Go Bigelow!
gigantino.tv - Heavy but weighs nothing.
I looked at the title and for a moment was stunned, thinking that NASA was actually working on building Project Orion. Now thers's a spaceship that really needs its shock absorbers.
http://www.nasaspaceflight.com/content/?cid=5167
Constrained by the Ares I launch vehicle, the SRD lift-off weight target for Orion is set at 64,450 lbs...
2.5% of total weight, to offset "massive vibration issues" sounds worthwhile to me, particularly if something important might come loose (or worse, break).
I worked on vibration testing for the shuttle, before even Enterprise was drop-tested. We were told to spec for x max level, tested to pass, and then 4 months later were told to re-test for 4x level. The whole damned thing had to be re-designed to include a big backbone, which made a major reduction in cargo bay. Well, it passed again, with the upgrade. Then the next year we were told that the actual levels were about x/2. Let's hope they have better cad and get it about right this time around.
But let's be clear: at launch there's a whole lot of shakin' goin' on.
Does someone have a car analogy?
Because they didn't design their engine very well, it now needs a very large harmonic balancer.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
some inefficiencies in other areas (like shock absorbers and weights) might be tolerable provided that such problems are not the result of more fundamental design flaws in the Ares rocket.
Well that's the thing, see. These problems are the result of more fundamental design flaws in the Ares rocket -- specifically, designing the thing with a single solid first stage to start with.
Solids give a notoriously rough ride. Liquid fuel engines are fed a smooth flow of fuel and are fine tuned to keep out any combustion instability or oscillation. Solids are just a big chunk of almost-explosive with a hole drilled down the middle -- once you light it, that's it. Except for ammunition (ICBMs, artillery rockets, etc), traditionally solids have been used in multiples, usually together with a liquid-fueled core. The advantage is that the thrust variations of multiple solids tends to average out -- you still get vibration, but not as bad. But Ares 1 went with a single, huge, solid stage. That's like designing-in a vibration problem.
On top of that, the damn thing is a hammerhead design, wider at the top than at the bottom (look at the picture, it looks like a corn dog). Those are notoriously prone to stability problems of their own. With liquid fueled engines with some throttle range and gimballed for steering, that's a minor issue. With a solid whose idea of throttle control is cutting the right shape hole down the middle so as to expose different amounts of burning surface at different times, and whose gimballing ability is, well, limited at best -- you'd better hope you don't have any unexpected issues with that inherent hammerhead instability -- like wind shear, or oh say unexpected excessive vibration.
The whole thing is a freaking kludge, and adding a ton of active dampening is just yet another kludge. The manned spacecraft division of NASA jumped the shark a long time ago, this is just further proof.
-- Alastair
Oh, it was WAY worse than that... just off the top of my head:
1) When landing on the moon, during the final (and most tricky) phase the computer controlling the LEM effectively turned off - Neil landed manually, with the computer yelling abort all the way.
2) Apollo 15 (I think) they tried decreasing the number of thrusters used to separate the stages - the stages almost collided, nearly killing everyone aboard.
3) Apollo 13, the center engine entered a pogo oscillation on launch that was about to destroy the craft until the computer shut it off.
There are lots more...
while (sig==sig) sig=!sig;
I read that headline dyslexically and thought it said "NASA Installing Shocks on Arse"
I thought it was about some new kind of employee training program involving electrified chairs so that managers could BZZZT someone not working :P
Maybe the vibrations are originating from multiple sources. It may be far more effective and cheaper to add active damping than to redesign the engines, the gimbals, the fuel pumps, the launch pad, and whatever else could be contributing to inducing these vibrations.
When our name is on the back of your car, we're behind you all the way!
>big, clunky, and with no regard for elegance.
Dealing with a vibration problem by adding nearly a ton of lead bouncy weights is not a great solution; especially when your mission is climbing out of a deep gravity well. They need to be looking for and fixing the source of the vibration.
Fortunately, they are. From Wired: "In the long term, Gary Lyles, associate director for technical management at NASA's Marshall Space Flight Center, said they are planning cold flow testing to learn more about the source of the vibration within the motor design itself. The next step would be sub-scale hot flow tests with solid rocket motors. If the tests prove conclusive, NASA will be able to look at doing a block upgrade to the motor and adding design changes to the full scale motor that will result in less vibration being produced. This would solve the problem without adding on extra weight to compensate for the problem."
Some mornings it's hardly worth chewing through the restraints to get out of bed.
The William H Zimmer nuclear plant was 97% complete when it became apparent that the plant owner and construction contractor had so screwed up the construction documentation that it would have taken as much money to recreate the documentation as it took to build the plant. From Wikipedia:
"Originally expected to cost $230 million, when the cost estimate soared to at least $3.4 billion the decision was made in 1984 to convert the plant. (Regulatory delays and high interest rates also contributed to the cost increase.)
The constructor, the Henry J. Kaiser Company, had never built a nuclear power plant before (or since). And the primary owner, Cincinnati Gas and Electric, did its own procurement, awarding contracts for equipment, e.g., for hundreds of valves, with inadequate specifications or QA requirements. Piping welds were not adequately radiographed.
Sargent & Lundy was the Architect/Engineering firm.
An ex-Navy admiral was hired to bring the plant on-line, and Bechtel was retained to nuclear-qualify the plant. However, Bechtel came in with an estimate of over $1.5 billion (to add to $ 1.7 billion already spent) to adequately complete the plant.
The conversion to coal-fired generation cost just over $1 billion, starting in 1987 and completed in 1991. It was the world's first nuclear-to-coal power plant conversion."
Just because the blueprints for Apollo exist doesn't mean that you can recreate the Apollo program. Lets just talk computers alone - where are you going to get flight control computers from 1969? Answer: nowhere - they don't exist. It doesn't matter if my TI calculator has more computing power; the cost to convert my calculator to recreate the function of the flight computer, test it, and rate it, would likely be far more expensive than just building a new one.
"As God is my witness, I thought turkeys could fly." A. Carlson
I remember reading about Apollo astronauts being amazed at how much they shook/vibrated - so much that they joked about not being able to make out controls (no one complained though for fear of loosing the missions)
Its not just the vibrations of the propellant exploding under their pants but the gimble of the engines to keep its trajectory that causes oscillations in the craft.. all being better absorbed by this awesome contraption.
Close, but there's a bit more to it than just being a 100% Oxygen environment. One of the things being tested was that the capsule would function properly experiencing the same outward pressure that it would experience in orbit. When the craft was in space, it would be pressurized at about 2-3 psi or pure Oxygen. To simulate that on the ground, the cabin was pressurized to 18 psi, 2 psi more than air pressure at see level.
In the aftermath, they realized just how stupid that was; at that pressure of pure O2, a bar of Aluminum would "burn like wood". Almost anything will burn, and many things will burn spontaneously. To make matters worse, almost every exposed surface of the module was covered in velcro for ease of use in zero-g. The problem is, the velcro was literally explosive at the Oxygen density used during the test.
Hilariously the apollo program had some pretty serious pogo oscillation problems. Pogo is shaking the rocket up and down makes the propellant flow increase and decrease making the oscillations worse.
In the apollo era, as per http://www.clavius.org/techsvpogo.html they used plumbing style water hammer chambers to eliminate the fluid surges. Let the vehicle shake but prevent the ability for shaking to cause thrust variations.
The modern solution is apparently dynamic shock absorber technology on the vehicle.
The modern solution eliminates the shaking, the old solution allowed it to shake but patched around it so it didn't have negative effects.
The modern solution is better, which makes the comparisons to Apollo kind of funny to those who know...
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
It's how much that weight has to be accelerated that matters. If you have to have dead weight, it's better to put it on the first stage than on a later one--you only have to accelerate that dead weight to first-stage burnout, rather than all the way to orbit.
The end effect is that a pound of dead weight in the last stage costs you a pound of payload... but a pound of dead weight on the first stage might only cost you a quarter of a pound in payload.
That's why many people propose making the first stage of a launcher reusable, and throwing away the upper stage (rather than the other way around, like the shuttle). All the reusability adds weight (thermal protection, landing gear, recovery systems)... make it the first stage, and you can make it beefier and more robust. And there's less of a thermal problem to deal with.
That said, 1600 pounds of deadweight mass dampers is a piss-poor engineering solution. But that's what you get when you have a politically-dictated design that's being rushed out the door; shit gets kludged together to make it work now instead of doing it right to begin with. This could be seen as the equivalent of using a GOTO in complicated code (instead of fixing it correctly), or fixing misaligned teeth by pulling them all out (to be replaced by dentures) instead of getting braces. It works, yeah, but it's not a good solution.
The meek may inherit the earth, but the strong shall take the stars.
As someone noted, there's plenty of margin in first stage.
Second point: If you look at the math for a two stage rocket, the effect of adding a pound to the first stage is inconsequential compared to the effect of adding a pound to the second stage. Sadly I'm away from my books (in a job transition at the moment) but the simple way to think of it is this: you only drag first stage with you for the first 2 or so minutes of flight, and then upper stage carries you for the next six minutes or so. So the weight is only with you for a short integrated length of time.
You can see this in effect when you consider the difference between first stage and second stage - first stage is essentially a modified Shuttle solid rocket motor, and second stage is essentially a re-designed external tank (yes, it's different, but the construction is the tank, thin wall aluminum with TPS).
First stage is thick, heavy steel, overdesigned for re-entry.
Second stage is thin, light aluminum.
The first stage is heavier, again, because of reuse and because mass isn't the design driver. Upper stage, however, since it nearly inserts orbit and is drug along the entire time is an incredible mass driver and must be as light as possible.
Sorry for rambling, and apologies for not showing the math, but in short, that's why adding 3/4 a ton to first stage isn't as big a deal as it sounds like. In the long run, it might effect maybe 10% of its weight in payload, if even...
Unfortunately - materials that were flame-retardant or flameproof in normal air became extremely volatile in the 100% oxygen atmosphere in the capsule. They changed to a different mixture after that accident.
Close but not quite. The materials were also flame-retardant or resistant at 100% oxygen atmosphere at the pressure specified for flight, about 3 psi. (The same as the partial pressure of O2 in normal air.) This they did not change after the accident.
The accident happened because they wanted to run the pad test at a higher pressure than the outside -- to simulate that aspect of flight conditions -- and so ran up the cabin pressure to 16 PSI -- of pure O2. Things that won't burn in 3 PSI O2 can burn quite vigorously at 16 PSI O2. Worse, NASA had been warned by North American about the dangers in a high pressure O2 environment. This procedure they did change after the accident, along with making a number of design changes on the CM.
(Ironically, one of the design issues on the CM was the inward-opening hatch, which Grissom had insisted on after the explosive bolts on his Mercury hatch underwent an uncommanded detonation after splashdown and he almost drowned. The inward-opening hatch meant the astronauts couldn't open it as pressure rose in the capsule because of the fire. The redesign included an easier to open, outward swinging hatch.) (Many years later, the likely cause of the uncommanded detonation of the explosive bolts is believed to be due to static buildup because of the recovery helicopter's downwash.)
-- Alastair
Except that liquid fueled engines weigh more than solid fueld engines...
Funniest, most wrong thing I've read on Slashdot today.
Hints: look up "specific impulse" and "combustion chamber wall thickness", among others. Hell, look at any kid's introductory book on rockets; it will explain in words short enough for you to understand why solids are (for a given delta-vee) so much heavier than liquids.
-- Alastair