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 the 16 canisters be connected to 16 switches? Are they gonna listen to snoop too?
Will they then have to haul nearly a ton into space? That sounds like a very costly improvement to the shuttle.
...and is a mechanical fudge. It looks to be typical American engineering, big, clunky, and with no regard for elegance.
Why don't we outsource the design to some German scientists, like we did the last time? European engineering is at least two grades above ours. We might as well get the best we can for the dollars we're paying...
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
Did they get'em on sale at NAPA?
It tried to find them, I put in the model is "Ares", but what do I put in for the "Make"?
Epic Fail !
Demotes Taco to cptntaco
Guns are for wimps... Use a crossbow.. this way you can pin them to their chair when you go postal.
Surely the addition of that much hardware would have a significant negative effect on the max possible payload?
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.
Sounds like they aren't planning on absorbing the vibrations from the engines, but canceling them with man made ones.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
You could so use the weights to give the spaceship hydraulics have it bumpin' and jumpin' through space. Pull up next to another ship and start hoppin' with some gangsta rap playing.
Why not just use the inertial dampeners from the puddle jumpers?
It takes a man to suffer ignorance and smile
Be yourself no matter what they say
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
I thought we were trying to preserve jobs for Shuttle contractors while giving them a good excuse to stop doing risky things like launching Shuttles. If our primary goal was to lift stuff into space, we'd have designed our stuff to fit on a heavy Delta or Atlas, so as to be prepared for the worst if the Ares I fails and prepared for the best if the Falcon 9 succeeds.
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 ;-))
Please understand there is a big difference between American engineering and government controlled American engineering.
The people are far better than their government, thats why the government mostly treats them as villians
* Winners compare their achievements to their goals, losers compare theirs to that of others.
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.
This seems like something the coyote would do to a rocket.
I wonder how this affects the steering mechanisms behind the Solid booster. Usually Solid Fuel motors are used in conjunction with Steerable Liquid fuel motors to control direction of thrust. Solids would use a "Steerable Skirt" to direct the Thrust.
Now they say that an O-ring failure is no big deal for this kinda setup for the Ares-1. But would a failure lead to a new thrust vector that could throw the whole vehicle in a uncontrolled spin/tumble? Could the steerable skirt be able to adjust to counter act this? I would imagine that where the failure occurred at would also dictate how effective the thrust vectoring would be to correct this. Could they arobt at this stage? If they went into a tumble could they abort? Would that tear the whole craft apart?
Would we "Need Another Seven Astronauts" or will it be "Need Another Six Astronauts" to reflect the new crew size for Orion.
Tsukasa: All I really want, is to be left alone...
Does someone have a car analogy?
Please give these guys a call http://www.directlauncher.com/
and then the marketing dept. plans on installing a really cool hood scoop!
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!
Wow, what a mess. Tell me again about all the cost savings involved in reusing components versus starting from a clean sheet?
Kwisatz Haderach
Sell the spice to CHOAM
This Mahdi took Shaddam's Throne
In medicine, it's called "allopathic", treating the symptoms. Doctors frequently do this because they're working from complaints and tests, not from a theoretical understanding of the systems. You can take aspirin for a headache. It'll probably work. You can't know without extensive testing whether that headache is due to a brain tumor (obSchwartzenneger: "It's NOT a tumah! It's NOT!").
A 4G vibration that's not felt by the astronauts but still occur in the vehicle could still rip the booster apart.
The DIRECT 2.0 alternative http://www.launchcomplexmodels.com/Direct/index.htm wouldn't have this problem. It uses mostly existing systems that have already been tested. (THIS is the real reuse of shuttle parts, not Ares). Yes, these have had their problems, but it was the engineers' idea, not something administratively mandated for them to design. I trust the engineers. When they ran things we had "failure is not an option" (Apollo 13). When management types took over we got "My God, Thiokol, what do you want me to do, wait until April to launch?" (SS Challenger). I'd sooner ride a non-man-rated SpaceX Falcon than anything devised by NASA management committee, much less something so devised then revised to eliminate the experience of the problem but not the problem. I'd at least like enough warning that something was going horribly wrong so I could scream.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
Shock absorbers now? This sounds more and more like the original project Orion every time I hear about it.
Couldn't they just build an improved Saturn V and pretend the shuttle never happened?
You're forgetting - this is a government job.
The contractors are close friends with the high-level bureaucrats. The contractors want to keep as much of their established and lucrative business in place, and the bureaucrats don't want to be bothered with making new deals (work?!) and possibly upsetting their friends who will likely give them much higher-paying private sector jobs eventually.
It's the usual NASA disaster. Too many cooks spoiling the soup, and none of them get much say in the shopping, since the steward is getting kickbacks from a third-rate grocer.
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
Seems to me it is about time NASA contacts Area 51 and puts an order in for those inertial dampeners we keep hearing about in Star Trek, Star Wars, BSG. My favorite is EE Doc Smith's Enertia-less drives.
Putting shock absorbers in a space craft just sound wrong. What's next? Fuzzy dice in the command module?
Life is a great ride, the vehicle doesn't matter
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 knew us Americans were growing obese...but was this really necessary?
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).
http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) Funny how things keep showing up over and over again. I wonder what the universe is trying to tell us.
It's not like all that weight is gonna come free.
Yes, but if the alternative is to reduce the power of the engines to have less vibration in the first place, then the net loss of payload may be greater than simply using the more powerful engines with the extra weight and shock absorbers. I suppose that I could be mistaken, I am not a rocket scientist after all, but if the goal is to maximize payload (which appears to be the case) then 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.
Awesome. Leave it to NASA to install more and more complicated parts on something until it's almost completely useless and costs a billion dollars per launch.
Next, failing to learn from other previous design mistakes, they'll install heat resistant tiles all over the thing.
Imagine if you weren't allowed to use roads because a bus company complained about your driving 3 times. --skunkpussy
To an outsider it seems that the US did a terrible mistake then they abandoned rockets in favor of the Space Shuttle. Yes it looks cool but its very expensive and not really the best tool for the job. The fastest way to get up to speed would be to side with some country that has good rocket technology instead of trying to build it themselves. It feels like this has more with politics than practical reasons.
This rocket has epic fail written all over it. If vibrations are an issue fixing those vibrations should be priority one, not mitigating them.
HTTP/1.1 400
And the starship will be piloted by captain Juan-Lucas Picante to seek out new life and civilations, to boldly immigrate and overpopulate where no one has gone before.
By the way, it's just the muffler that's dragging and kicking up the sparks. It requires duct-tape maintenance at the nearest star-garage. After the ship is decommissioned, it will serve as a museum and die while sitting in somebody's front lawn.
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.
Why do I get the feeling that NASA is trying to hack a rocket together? NASA had suitable rockets in the 70s and then there is the Russian Space Agency and the ESA which already have viable heavy lifers. Maybe NASA could just license the designs of existing systems?
Jumpstart the tartan drive.
First vibrators getting stuck on Mars, then NASA installs shocks on the rovers...
Sounds like there is a playmate up there for Wall-E :)
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
I wonder if this alternative designed by NASA engineers in their spare time would require shock absorbers: http://www.launchcomplexmodels.com/Direct/index.htm
Will the engineers who actually know about these things be able to prevent this kludge from becoming operational or will NASA management and political appointee administrators strike again? It is probably the dream of every rocket engineer to design a new vehicle from scratch and somehow NASA manages to squander this once in a generation chance to "get it right" after years of just gritting their teeth and "making it work" with the shuttle. I suppose that I shouldn't be surprised, but it is still disappointing to see so much money being wasted on dumb designs, like Ares is shaping up to be, when it could be going instead to Burt Rutan of Scaled Composites or the guys at SpaceX if it has to get spent at all. Personally, I would prefer more advanced propulsion research and unmanned missions with a minimal manned program just to keep the technology going rather than more high-cost, low-science, space cowboy-style boots on the ground and flag in the sand missions to the moon and mars. The big manned program should wait until we have somewhere really interesting to go and a better way to get there than chemical rockets (think NX-01).
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
anyone else read this as "NASA Installing Shocks On Arse"? sad that the thing needs such a goofy solution as shock absorbers. is there no way to build baffles or something in the engine to eliminate these vortices?
Confucius say "solid rocket on man-rated vehicle not solid idea."
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
so what are they? koni's ? bilsteins? kyb's? or are they lowest bidder ebay deal of the day? will it help cornering g's?
The would-be SF writer in me wonders if it would be possible to redesign the craft to passively eliminate any hazardous oscillations, by making sure that the structure doesn't have any resonances near the frequencies put out by the engines. The doesn't-want-to-be engineer in me has absolutely no idea how feasable this is, of course, but it'd be a mechanically graceful spacecraft for a more civilised age.
No kidding!!! What do you say at this point?
Xhibit and the guys at NASA will take a stock Ares-1 and turn it into a tricked out machine.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Am I the only one that noticed that this thing is based on the Shuttle SRB, the very thing that caused the Challenger disaster?
Epic fail is right.
Why not use a big crane instead? It's not like fuel will be much of a problem in space.
>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.
They should just slap on a couple of those top secret Oscillation Overthrusters. Then their stupid Ares rocket could travel all the way to Planet 10 in the 8th dimension!
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.
Well, batteries are heavy, maybe they can double as the weights and provide extra power for the mission.
A-Bomb
So, is that how the Inertial dampers on the Enterprise worked?
(cheap...couldn't resist)
A space-age version of the rusty springs under old pickup trucks will help NASA fix the most pressing technical problem with its high-tech new rocket to send astronauts back to the moon. ... Officials on Tuesday said they have settled on a solution that is similar to what smooths the rides of pickup trucks: shock absorbers.
So are they springs, or are they shock absorbers? It's pretty sad that an "AP Science Writer" doesn't know that these are two completely separate things.
Million-dollar race cars also have shocks and springs, as do other forms of exotic machinery. It's cute how he implied that it's some kind of archaic concept limited to "old pickup trucks," though.
Could these pathetic hacks at least TRY to report things accurately and with a shred of objectivity? Christ.
You made the fundamental mistake of assuming the parent to your comment knew what he was talking about. Blah, blah, solid vibrates more than liquid, blah blah.... Oh well he must be right! Let's fire those engineers. Let's hire SpaceX! Except that liquid fueled engines weigh more than solid fueld engines... Probably much more than the weight of the shock absorbers... And SpaceX's rockets keep vibrating themselves to death.
Yay armchair rocket-science!
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.
Call them inertial dampeners!
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.
Apollo pogo'd pretty well. Maybe a solid Apollo would have pogo'd worse. You seem to be implying that liquids don't pogo which is blatantly in error.
Combustion instability and oscillation and smooth flow of fuel refers to the flow of cooling gas in the engine, basically a swirly gas flow increases heat flux by a large factor until the nozzle melts. Howling engines come from low pressure drop across the injector, as regards your "smooth flow of fuel". You're using the wrong words.
You are correct that the solid stage is a huge mistake, but politically necessary.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
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...
Clearly. . . they need an oscillation overthruster.
This is NOT "..essentially remote-controlled shock absorbers" Mr. Garry Lyles!
As a MechE & former motorcycle racer I have tuned shock absorbing systems.
Steel & air Springs absorb the force & motion, oil dampers dissipate the energy as heat.
This system actively uses Newton's 2nd (F=ma) to provide an active inertia force opposing the vibration!
This is very like a Bose sound-canceling head set, NOT automotive "shocks"!
it is still disappointing to see so much money being wasted on dumb designs, like Ares is shaping up to be, when it could be going instead to Burt Rutan of Scaled Composites or the guys at SpaceX if it has to get spent at all.
OK, let's compare.
NASA: Ares 1, problem identified in the design stage, solution proposed.
Scaled composites: One spaceship built, three flights to space altitude (but not orbital velocity) before spacecraft retured; one explosion, three people killed.
Space X: three flights, three failures.
Now, I love these guys' energy and enthusiasm, but their success record just ain't there yet.
Apollo had a pogo suppression system installed after A13 which worked just fine. Pogo is expected on new liquid designs, part of the engineering process is to determine the sources and fix them. Once it's fixed, it's fixed.
By smooth flow of fuel I meant a continuous, predictable flow of combustibles to the combustion chamber, as compared to a solid, where the whole thing is a combustion chamber and all the fuel is already in there, so it just burns -- at a rate dependent on surface area, fuel consistency, and chamber pressure. If there's a crack in the grain, it detonates. However, solids don't pogo.
Combustion instability is just that -- anything that prevents smooth combustion of propellants in the combustion chamber. Resonance can be a prime culprit, if acoustic waves at the resonant frequency of the chamber build up they can alter the reaction rates in different parts of the chamber, with runaway feedback that eventually destroys the engine. The usual design around is to arrange engine surfaces and injectors at angles and in patterns designed to prevent resonance. Inconsistencies in injector flow, due to throttling or unintended effects like pogo or pump cavitation -- can also lead to instability.
As for "the flow of cooling gas in the engine" -- that's highly engine dependent, many engines don't have such a thing. The injectors and injector face are typically cooled by the propellants flowing through them, and chamber walls are often cooled by pumping the fuel though cooling passages before injection. The F-1 engine did dump its turbine exhaust gas into the engine bell about halfway along its length, which did cool the lower end of the bell (relative to the main exhaust stream). Smaller engines with shorter burn times might just use passive cooling, of course.
-- 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
You got marked as a troll for this. Yet you are 100% correct. How very sad.
How very very sad that Americans, who led the space race, and used to make the best cars in the world, now couldn't build a car to save themselves, and after building the stupendous Saturn 5, now find themselves incapable of building a basic launcher (based on 50 year old "techomology") without fucking it up badly.
No wonder 'Merka is in trouble everywhere it looks.
How many escape pods are there? "NONE,SIR!" You counted them? "TWICE, SIR!"
Homer: "And this racing stripe here I feel is pretty sharp."
Burns: "Agreed! First prize."
Make the harmonic balancers (my phrase) serve some other function then... perhaps they can hold fuel, or electronics, or be antennas. Just not deal weight that moves up and down.
As a programmer, I can smell a kludge from a mile a way. This is a kludge times 17
You were mistaken. Which is odd, since memory shouldn't be a problem for you
European aircraft design is elegant...
http://www.usatoday.com/travel/news/2006-06-13-a-380-usat_x.htm
Whereas American aircraft design is clunky and not timeless:
http://www.nytimes.com/2006/12/25/opinion/25mon3.html?th&emc=th
You were mistaken. Which is odd, since memory shouldn't be a problem for you
Maybe NASA is trying to, you know, innovate? This generally involves "untested principles"
Why do we have these so called engineers here questioning everything and saying they would do 100x better? This is kind of sad.
Solid boosters tend to have less moving parts, so their problems tend to only be related to design and manufacturing. No pluming and turbo-pumps to worry about. No pogo. The only issue right now is vibration and reducing crazy 6G vibrations down to 0.25G is great work.
Frankly, I like the current Nasa concept of using solid fuel booster like this.
BTW, #3 is false. #4 is not correct either.
you are a European who has a strongly over inflated sense of your engineering? Take a look at how long it took to create A-380 or your Arian rocket. So far, the only engineering that I see as superior from EU is the german cars (nice, though I think that tesla will shortly be giving you a run for your money) and that has more to do with American business screwing up. "If it ain't boeing, I ain't going" as the saying goes. Same for rockets in my book.
The astronauts selected back in those days were military test pilots who were cool and calm under extreme pressure and who could exercise good judgment in life and death situations. Kind of like Tom Brady in the super bowl times 1000.
They selected those kinds of guys because those rockets were extremely experimental. It's only 40 years later that it seems trivial what these guys accomplished. The state of the art in 1969 was so low that going to the moon in the Saturn/Apollo would be trying to paddle from LA to Australia with a rowboat and heath bars for food. A rational person wouldn't do it.
You were mistaken. Which is odd, since memory shouldn't be a problem for you
A ton of shock absorbers in space but still no way of absorbing the shock that there is no thrust left for a payload.
The reason the shuttle's payload seems so low is the orbiter itself... it's not "useful" payload per se, but in terms of absolute mass delivered into orbit, the shuttle system (as a whole) is right up there in the same general category as Saturn V, Ares V, and Energia.
We could have leveraged a lot of that capability had we so chose... look up Shuttle-C
The meek may inherit the earth, but the strong shall take the stars.
Which is the whole point of using inherently man-unratable solids for Ares. It is a stupid idea, and if actually implemented, will take lives. There are lots of better options out there from Delta Clipper, which would have been flying for years now if Algore hadn't granted Lockmart a boondoggle with the X-33, Delta IV Ultra-Heavy, the Jupiter mod of the shuttle stack, using delta cores instead of SRBs, Energiya, and many more.
deliberately, in order to keep anyone about rethinking the whole shuttle issue. Now, we -can- start over and make liquid rockets to do the job, though lacking the F-1 engine - and engines are expensive to design and test - we might have to use lots of smaller engines, such as the Falcon-9 uses.
While solid fuel gives you more even combustion there is no such thing as a timed or controlled burn - once you start it keeps going until the all the fuel is gone and there is no way to control the rate of burn.
Not the same as a "shock absorber." If they are driving the masses with motors to mitigate the vibration, it is effectively closed-loop vibration control-- with the objective of adding damping to the resonant peaks causing the problems. A shock absorber, like the one on your car, adds damping passively. (It blunts the resonant peak of the heavy car riding on the reasonably cushy springs.)
The devices that they are describing sound like proof-mass actuators, which would have to include the drive electronics and power supplies to do what they are proposing-(in addition to the control computer.) If I am not mistaken, the vibration energy can be redistributed to other modes (or across the spectral response in general), as well as dissipated by the amplifier as heat.
Think of it as a "smart" accelerating mass that causes forces which oppose the disturbance forces, but which can also introduce vibration problems of their own.
You know what it sounds like? A grab for money. I bet they get XXX dollars, and then revert to a simpler passive design.
NASA Installing Shocks On Arse.
Will the engineers who actually know about these things be able to prevent this kludge from becoming operational or will NASA management and political appointee administrators strike again?
According to a friend of mine who is actually working on the Ares project, there are a lot of people that would rather go with the Jupiter or re-roll the Saturn V with some slight modifications, and believe the current design is basically a means to satiate NASA management, Morton Thiokol, and other contractors and their Congressmen who stand to lose a lot of money if Shuttle-derived components aren't used in the new system. In short, it's the most politically expedient design, not the best design, and what the engineers really think doesn't seem to factor into these kinds of decisions.
Please stand clear of the doors, por favor mantenganse alejado de las puertas
They are redesigning the Apollo launcher, using the same 'committee' design process used for the shuttle. Well we all know how well that went.
Still there is always room for declination.
My ism, it's full of beliefs.
Instead of "weights" they should use flywheels or batteries, or fuel tanks, or water tanks. Something potentially useful.
I hold very few opinions. I hold information based on observation and fact. If you wish to disagree, please use facts.
And what ideology do you suppose that I have? I'm not claiming private enterprise is totally superior in every way, and I didn't suggest that Delta/Atlas be chosen because they were "privately" developed or inherently superior. I only said that this particular program is being cocked-up because of political interference, and that Delta/Atlas would have been better for this application because they were already flying and they are better rockets than Ares I.
If anything, my "ideology" would be "let's give them the funding they need to do it right, instead of politically forcing poor design decisions in an attempt to run a jobs program or keep somebody's constituents happy." I'm tired of seeing politicians and bean-counters fuck up good space programs--it happened with Apollo (canceled early), it happened with the shuttle (too many problems to list), it happened with ISS (too many design compromises), and it's happening with this program. But sadly, I think it'll take an imminent "dinosaur-killer" asteroid or some form of alien contact before anyone treats space seriously.
For the record, I have libertarian leanings. But space is one of the few areas where I do support large-scale government involvement.
The meek may inherit the earth, but the strong shall take the stars.
This is the vehicle that ATK Thiokol tried to sell as "Safe, Simple and Soon"
Oh, well.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
Why not use a pair of three segment solids as the first stage instead of a single 5.5 segment solid? The extra thrust might even exceed the weight penalty of the extra structure needed. The whole vehicle would be shorter, lessening control worries. Finally, the pressures produced in the three segment design wouldn't require the same high-pressure design/development the 5.5 segment design does.
Mount it on the Space Elevator?
I just read Slashdot for the articles.
(Ivan 256 wrote): Except that liquid fueled engines weigh more than solid fueld engines...
(AJW replied): Funniest, most wrong thing I've read on Slashdot today.
Hints: look up "specific impulse" and "combustion chamber wall thickness", among others.
It really depends on what you're referring to. Liquid rockets (can) have higher specific impulse, that is, total impulse per mass of fuel burned. Solids, on the other hand, typically have much greater thrust to weight ratio.
For a first stage, high thrust is much more important than high specific impulse, so, despite your comment; it's actually reasonably accurate; for a given required level of thrust, liquids most likely do "weigh more than solid fueled engines."
And of course, solids have the advantage (and disadvantage) that once lit, it's lit. There's a lot less to go wrong (provided you avoid o-ring problems) and a lot less pre-flight complexity to get it ready to go.
I can't bother to log in - but what I haven't heard here are the ADVANTAGES from using a solid. Light and forget. They are very reliable - the nice thing is that once you light the solid you are almost guaranteed (!? - no guarantees in rocket science of course) to get enough altitude to use the escape system if the second stage doesn't light. Liquid fuel is hard to do - solid is relatively easy. So this is a simple way to throw the capsule into the air. If it weren't for the poor specific impulse of solids we could just go with solids which are much much easier. As HAS been mentioned previously there were massive pogo problems on Gemini and Apollo - and there were heavy systems to alleviate them.
Before we who are not rocket scientists bemoan the stupidity of this decision we really would need hundreds of hours of intro to all the caveats in all the systems and decisions in order to give a valid argument.
(jaytee@deepspace.force9.co.uk)