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.'

Comments

It's simple to solve this problem

[ThreeGigs]

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.

Re:It's simple to solve this problem

[corsec67]

Actually the way I read it is the problem is in the gas inside the solid booster having turbulence that leads to vibrations. Thus it isn't dependent on the structure of the booster, but on the way the fuel inside it is shaped, at ignition and during the burn.

But, I am not a rocket scientist.

Re:It's simple to solve this problem

[ThreeGigs]

Yes, it's the gas that causes it, which would ordinarily just be a rumble. However, the frequency of the rumble apparently matches one of the harmonics of the rocket casing or motor, which causes a nasty bit of positive feedback.

Much like bouncing in the middle of a board. Changing the frequency of the input force means you won't go as high, changing the mass (lighter or heavier person) means the resonant frequency changes, making the board out of something stiffer or less stiff changes the optimum rate of bouncing...etc.

Re:Nasa

[wjsteele]

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

Apollo Called: It Wants its Saturn V Back

[segedunum]

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.