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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?"
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.
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?
Just about anything can be a "weight". It's in their best interests to make the weights serve (another) function.
Also, the weights are almost all at the bottom of the rocket, so they should only affect the first stage.
How can I believe you when you tell me what I don't want to hear?
How much do you suppose a "small" damper on the fuel line weighs on a 6.7 million pound rocket? I couldn't find any answers, but it would not surprise me if the Saturn V's "small" pogo suppressors weighed over 1600 pounds in total.
If you mod me Overrated, you are admitting that you have no penis.
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
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.