Ares I: vibration self-destruct?

[holmec]

<blockquote><font class="small">In reply to:</font><hr /><p>No, the un-acceptable vibration does not exist in the STS stack because of the vehicle configuration.<p><hr /></p></p></blockquote><br /><br />Does this call for a redesign of the first stage casing to add stability? <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[frodo1008]

Why would you think that ATK wants some $3+ billion for the design and testing of the new 5 segment SRB. It IS an entirely new booster!!

 

[gunsandrockets]

<If anyone has details or sources for the statement that the D-IV trajectory is unacceptable for human launch due to "lofting", "black zones" etc. I hope you'll post them. We should try to pin down the facts.><br /><br />I don't have the link handy, but I was recently reading some NASA history about the Mercury program and the whole issue of 'lofting trajectory' did come up as a possible roadblock to Mercury. USAF was convinced the g-level was too high during an abort. But actual centrifuge testing proved that the g-level was survivable and the Mecury program with a ballistic capsule lofted by an ICBM booster went forward.<br /><br />I am extremely skeptical of the reasons put forth by ESAS that EELV are unsuitable for use as the Orion crew launch vehicle. <br />

 

[no_way]

On the "black zones", this was discussed on NSF forums to death, and everyone with a wee bit of info basically said that this is a solved issue.<br />ESAS basically disregarded the solutions ( corrected flight paths ) that had been puth forth by EELV operators already for OSP and used the old, no longer valid "black zone" argument against the EELVs.<br />Thats the summary of the long threads discussing it. I didnt see anyone countering it with data to indicate otherwise.

 

[usn_skwerl]

real quick question; what is lofting in reference to? <div class="Discussion_UserSignature"> </div>

 

[docm]

def: Lofting<br /><br />to propel in a high arc <div class="Discussion_UserSignature"> </div>

 

[usn_skwerl]

I know what lofting by definition is, but I don't think that quite answers my question....I meant in reference to <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>I don't have the link handy, but I was recently reading some NASA history about the Mercury program and the whole issue of 'lofting trajectory' did come up as a possible roadblock to Mercury. USAF was convinced the g-level was too high during an abort. But actual centrifuge testing proved that the g-level was survivable and the Mecury program with a ballistic capsule lofted by an ICBM booster went forward. <br /><p><hr /></p></p></blockquote><br /><br />How does a 'lofting trajectory' factor into a predetermined, preprogrammed lauch profile? <div class="Discussion_UserSignature"> </div>

 

[vogon13]

IIRC, 'lofting' in regard to a shuttle launch is being higher/faster than expected at a given point in the time line.<br /><br />It seems like the first shuttle launch (Columbia) had solid rocket booster burnout at least a kilometer higher than expected. This was indicated in a radio call from capcom that informed Columbia's crew they were 'lofting'. In that case, probably a good thing, burnout 10 kilometers too low would indicate a major shortfall in achieving the desired orbit. Looking at various abort scenarios, you might be pushing up on an 'out of envelope' experience the abort sequence might not handle correctly.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vulture2]

>>There should be a frequency associated with the 1G.<<<br /><br />Sorry about the delay, S-G. Here is the vibration table for Delta IV. The actual peak frequency is not given, nor can I find the amplitude of the Ares I vibration. <br /><br /> Table 4-7. Delta IV Sinusoidal Vibration Levels<br /><br />Axis________________________Frequency (Hz)__________Maximum flight levels<br /><br />Thrust_Axis_________________5 to 6.2Hz_______________1.27 cm (0.5 in.) double amplitude<br />Thrust_Axis_________________6.2 to 100Hz____________1.0 g (zero to peak)<br /><br />Lateral______________________5 to 100Hz_____________0.7 g (zero to peak)<br /><br /><br />This is just a spec, not a measurement. But 1G at 100Hz is only .07mm peak-to-peak, At the other extreme is 6.2 Hz at 12.7 mm peak-to-peak. Even this is less than half an inch and could be damped by seat mounts. I think we can reasonably say that the DIV doesn't have a problem with vibration. <br />

 

[thereiwas]

For comparison, according to the SpaceX F9 Data Sheet, "The Falcon 9 is not expected to have a sinusoidal environment present at the base of the payload interface. " The spec sheet does call out details of the acceleration forces to be expected at different stages of flight (see page 4), and the acoustic environment. Major bumps at MECO and 2nd stage start and CO.

 

[vulture2]

"The Falcon 9 is not expected to have a sinusoidal environment present at the base of the payload interface."<br /><br />This seems like a rather optimistic statement - there is always some vibration. Nevertheless apparently none of the all-liquid-fuel launch vehicles used for human space flight (Soyuz, Redstone, Atlas, Titan, Saturn, Long March) had a vibration level sufficient to be problematic. There's no reason to believe either the Falcon or Delta IV-H would have a problem in this area.

 

[vulture2]

Point taken; I forgot about these. Nevertheless, the vibration on Shepherd's flight was due to transonic buffeting, not the engine. The pogo on the Saturn was essentially a fuel flow control problem and was elminated on later launches. Eliminating vortex shedding from a large solid fuel rocket, by contrast, would be difficult or impossible. <br /><br />That said, if anyone has any information on the actual magnitude of the expected vibration, please post.

 

[edkyle98]

JO5H wrote:<br /> />>"When the first Ares I snaps in half mid-flight, people are going to ask "why is it so long and skinny?""<<<br /><br />You're joking, right? <br /><br /> - Ed Kyle<br />

 

[edkyle98]

>>"I'm only discussing Block 1 Orion (orbital) - AFAIK the Lunar-capable Orion is still to heavy for Ares I."<<<br /><br />There is no "Block 1 Orion". There is only Orion, which is being designed for the lunar mission but will fly to ISS a few times. It can do ISS with less propellant than it will need for the lunar mission.<br /><br />NASA's statements on Orion/Ares I development progress say nothing to suggest that Ares I will be unable to lift Orion on a lunar mission. The idea that NASA is purposefully developing a spaceflight system that cannot accomplish its mission is absurd.<br /><br /> - Ed Kyle

 

[radarredux]

> <i><font color="yellow">The idea that NASA is purposefully developing a spaceflight system that cannot accomplish its mission is absurd.</font>/i><br /><br />I think the old phrase "What did they know? And when did they know it?" may come into play.<br /><br />I <i>really</i> hope they can work out the problems (I think virtually all of us would prefer to see success in a timely fashion), but <b><i>if</i></b> at some point it does turn out that the stick is a very un-optimal (or unusable) selection, at some point someone is going to ask the NASA leadership why they kept betting on (and funding) a loser of a horse.</i>

 

[Testing]

POGO was simulated at COCA A-3 on SSME test at different frequencies by a hydraulicly controlled piston in the (I believe) LOX supply line. <div class="Discussion_UserSignature"> </div>

 

[drwayne]

The Pogo that occured at one point or another on all three stages of the Saturn 5 was never eliminated.<br /><br />It was mitigated by some hardware additions and adjusting some of the engine shutdown profiles, but it was always there.<br /><br />Fortunately - cavitation was only induced in one manned flight.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[Testing]

Keep in mind that no vehicle or component of spends a great amount of time at any or a low frequency. The important thing is to transit a Resonant frequency quickly. Resonance = Q or Amplification. Bad <div class="Discussion_UserSignature"> </div>

 

[Testing]

Concur that flight test is the final verification data point. But simulation on the ground tells ya what to expect. Send me a PM when you know your Western schedule. <div class="Discussion_UserSignature"> </div>

 

[drwayne]

If you look at POGO work on the Titan II, it is actually very interesting trial and error. They tried some approaches that they were sure would work that made things much worse.<br /><br />The Shuttle by the way, because if is an asymetric stack, is less prone to POGO from the start.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[Testing]

Re-inforced Eggnog, tree and fire available 12-15 on. If current on off wind patterns continue you will not be landing here. <div class="Discussion_UserSignature"> </div>

 

[drwayne]

"Re-inforced Eggnog"<br /><br />Sounds like "solid" fuel to me. <img src="/images/icons/wink.gif" /><br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[Testing]

Additional Testing required. A sample of one is a single data point. <div class="Discussion_UserSignature"> </div>

 

[drwayne]

LOL, thanks for that!<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[j05h]

<i>> There is no "Block 1 Orion". </i><br /><br />Whatever you want to call it. They've talked about different heat shields for different missions, plus other possible changes. NASA's documentation referred to a Block 1 Orion, my apologies if my info is out of date. It's to bad if they did drop the Block designations, as variants and planned design evolution are powerful leverages of a technology.<br /><br /><i>> NASA's statements on Orion/Ares I development progress say nothing to suggest that Ares I will be unable to lift Orion on a lunar mission. The idea that NASA is purposefully developing a spaceflight system that cannot accomplish its mission is absurd. </i><br /><br />There are persistent rumors about roadblocks due to Ares underperformance. I'm not saying they are doing this on purpose, quite the opposite. This is happening because some Good Ol Boys didn't fully vet their concept before making it public, then moved the goalposts when it turned out the original idea couldn't work. The original Ares was an interesting stop-gap (SSRM, SSME) that has grown into something much different. The proper move would have been to re-compete the ESAS launcher in late 2006, when it was obvious that Ares I was not what it seemed. <br /><br />Last, the entire Ares architecture, even if built, will just barely not break the bank. This is again because of designing the payload around the rockets and political budgets. HLV is not needed for going to the moon or anywhere else. Ares I is touted as a MLV that will add to the HLV, but in fact it is entering into a market already overloaded with MLVs that will put it to shame in capabilities and price. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>