3rd (possible) CLV problem: too much "G" for crew?

[najab]

gaetanomarano, you don't have a clue what you're talking about.

 

[darkenfast]

Geatanomarano, if you actually would like to learn something, please read the following carefully.<br /><br />The burning characteristics of a solid rocket are controlled by the shape molded into the fuel. The shape used on the SRB's has been analyzed for over 20 years. The designers and engineers who are working on the CEV know how much thrust it will generate during each portion of its flight (it is varied from moment to moment, as the rocket takes off, goes through the sound barrier and finally, approaches burn-out). The solid isn't controlled during the flight, but the performance is "programmed-in" when the fuel is installed. They know approximately how much weight will be in the CEV/SM and the Upper Stage. Therefore, they know the g-forces. NASA has rules on how many g's can be sustained for how many seconds, both by conditioned astronauts and unconditioned/unhealthy astronauts, and for emergency aborts. The CEV will remain within those limits, even on a lunar return, which is harder to achieve than on the launch. The physical requirements should be no different than the Soyuz. The ten g's of the escape system are only for about five seconds, and are borne in the most advantageous position possible (the Apollo-style couches, which are quite a bit longer than those on Soyuz/Shenzhou), as are the high g's of an emergency re-entry from a high altitude abort. <br />

 

[josh_simonson]

I said something earlier about reading and comprehending the report in order to not look a fool. Anywhoo...<br /><br />Here's a exerpt from an interview with someone that rode both the shuttle and soyuz:<br /><br />7. How would you describe differences in the g forces experienced aboard a Soyuz vehicle compared to those on the space shuttle?<br /><br />One of the differences between a space flight aboard the space shuttle and aboard a Soyuz vehicle is the g forces that are experienced by the astronauts or the cosmonauts. In the Soyuz vehicle, the g forces on launch are through the chest in this direction here, about 4 gs or so, which makes breathing a little bit difficult and during re-entry although the g level can be higher, 4, 5, 6, 7 gs, again the g-force factor is in this direction here, through the chest which mainly will make breathing rather difficult, but not much more than that. <br /><br />On the space shuttle during launch again, the g-force factor is through the chest—a little bit less of a load on launch—about 3 gs compared to the Soyuz vehicle. The big difference though, for the shuttle is that when the astronauts return home, the g-force factor is felt from head to toe. It's a relatively low g level, about 1.8 gs during re-entry, but the fact that the g vector is from head to toe causes blood to pull a little bit more in the lower extremities and that can make some astronauts on a shuttle return feel a little bit light-headed for the first few minutes after they have landed.<br /> <br /><br /><br />What's interesting is the CEV has a max of 4 g's on re-entry. That's much better than soyuz (and why CEV is so large for the mission - more drag=less g's).

 

[drwayne]

Looking at the data, the maximum G loading occurs well after 1st stage speration - the data above the chart that was posted states:<br /><br />max SRM acceleration = 2.26 <br /><br />which is consistent with the plot, the dip in the curve is the staging event.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[drwayne]

It doesn't look like it from my reading sir. Now I may be misreading the report (around page 44, section 6), but it doesn't look like anything other than model data for a 4 segment SRB based system.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[gaetanomarano]

<br />the data posted from shuttle_guy and josh_simonson evidence a (certainly not little) acceleration of CEV at launch and reentry<br /><br />well... excluding some astronauts-scientists... a moon mission with CEV, that accelerations, an high level of risk (much more than an, already risky, orbital flight) ...the high level of training and specialization of a moon missions (it's not like drive a car...), etc... the question is...<br /><br />it may be a flight for ALL ("all" in "Shuttle terms", not literally) or a flight for very selected "high-G-high-risk" peoples?<br /><br />many wants to be an astronaut, but, after space agencies' hard selection, only a few can fly... many of them are former military pilots<br /><br />from the answer to this question (expecially the TRUE answer, after TRUE selections) descend the kind of missions (and results) we can have from moon... more "walking & jumping" or more "science & research"?<br /> <br />PS - the 10G acceleration of LAS is only for 5 (or 3) seconds and may happen ONLY in the (we hope) RARE need of a launch abort... but a launch abort (with 10G eject) IS part of a flight... astronauts must have a resistance to survive to that acceleration (why put a LAS to save them if they can't survive?) ...this further reduce the number of people that can REALLY fly with CEV missions

 

[najab]

gaetanomarano - you don't know what you are talking about. Please stop posting, it's gone beyond embarrassing.

 

[gaetanomarano]

<br />my question was to shuttle_guy... he may decide by himself if the question is "embarrassing"

 

[drwayne]

So the interesting part is the highest acceleration is not in fact caused by the solid fueled first stage.<br /><br />That is what I suspected. Usually the G's go up later in the mission when the vehicle is in a high and light configuration.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[drwayne]

Fascinating reading Josh, thanks for the gentle prodding to read it.<br /><br /><img src="/images/icons/smile.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>

 

[tap_sa]

<font color="yellow">"it may be a flight for ALL ("all" in "Shuttle terms", not literally) or a flight for very selected "high-G-high-risk" peoples? "</font><br /><br />If passengers are topguns they can handle the high Gs.<br /><br />If passengers are scientists they are so fat the increased crew mass keeps Gs at manageable level for non-topguns.<br /><br />See, no problemo.

 

[drwayne]

"In the case of the CLV the highest is at the end of the second stage burn due to the high thrust of the SSME relative to the payload weight."<br /><br />Yep, high and light. Kind of like my brain. <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>

 

[gaetanomarano]

<br />compliments for your brilliant (scientific) deduction

 

[drwayne]

Would you please stop making fun of my weight. I am going on a diet right after the holidays!<br /><br /><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>

 

[drwayne]

"Fortunately the SSME can be throttled down."<br /><br />Yeah, I figured that there was a throttle down later in the profile.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[tap_sa]

<font color="yellow">" I am going on a diet right after the holidays!"</font><br /><br />Sir, please reconsider if you ever want to visit space! NASA has quite demanding minimum inertia requirements for scientist-astronauts! I've heard rumours that even before lunar flights start NASA will be giving CEV rides to skinny, non-topgun space tourists and will need scientist or two just for a ballast!<br /><br />(OK time to hit the sack...<img src="/images/icons/crazy.gif" />)<br /><br />

 

[SpaceKiwi]

Speaking of throttle, there's going to be one of the neck-variety if these idiotic threads keep appearing.<br /><br />I am one of 'scientific illiterate' and even I can see the stupidity of the original premise, which was put forward in the complete absence of supporting data, and could have been argued from the opposing point-of-view (that the G-loading is entirely managable for the average human) if the poster didn't have a biased agenda.<br /><br />Is it just me, or is this even <b>more</b> annoying than our Dobson friend? <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[josh_simonson]

Nasa identifies 4G (eyeballs in) as the max load that 'deconditioned' people can stand. That includes non-professional astronauts and even unconcious, sick or injured folk. Robert Thirsk, the astronaut I quoted, didn't seem to think it was a big deal either, though he's a profesional.

 

[frodo1008]

You are the last poster, so this isn't in regard to your posts themselves. As GT (I get tired of writing out his complete name here, so from now on he if GT to me, hopefully he will not object) has stated he wanted just facts, and no attacks on him. I know this will be difficult due to his past ignoring of ANY facts in his posts, but I will try something here without such rancor anyway.<br /><br />As the SRB's provide some 71.4% of the total thrust for the entire shuttle system during the time that they are actively thrusting (about the first two minutes of flight) for all intents and purposes the amount of G's for the single stick SRB CLV/CEV configuration is going to be the same as for the current STS system. <br /><br />So those that can withstand the G values of the current system should be able to withstand the same G forces for the first stage of the SRB single stick SRB system. Now there has even been a problem with the shuttle having two very powerful solid rocket motors both firing, this developes various resonant frequencies between both motors (and quite possibly also the three SSME's). This makes for a very rough ride up until the SRB's are cut off and the SSME's take over for the last 6.5 minutes of a shuttle flight. This sproblem dosen't exist for the three SSME's and the ride smooths out considerably when only these engines are thrusting.<br /><br />Now, in another thread (I think it was shuttle_guy that brought it up, or answered someone else's query) it was noted that with only one such SRB firing this problem would for the most part go away, and even the first stage with only the SRB thusting would be considerably smoother for the people on board!! So, in actuality not only is this problem no worse than the present shuttle system, but it is quite probable that it would be quite a bit better!!<br /><br />Which makes this entire thread moot!!!!

 

[gaetanomarano]

<br />you can see that in thread's title there is the word "(possible)" and it ends with "?", not with "!"<br /><br />also, in my first post of this thread, I clearly use the "G" argument as a way to talk about a much more important question<br /><br />great part of the post is not about CLV solid-engine "G" (that may be like a liquid-engine rocket or not... we will see with real flights) but about the change of policy in space flights<br /><br />you may agree with me that the era of "normal peoples" and "scientists in space" born with SHUTTLE and with its low G, large cabin, 16-days missions, runway landing, etc.<br /><br />with the (liquid or solid engines) CEV/CLV, we will come back to the Gemini, Apollo, Vostok, Soyuz cold-war-moon-race era when, due to high-G-capsule and risky-missions, astronauts was captains, colonels, liutenants (of US Navy, USAF, Soviet Red Army, etc.) and a few "civils"<br /><br />all respectable and brave peoples, of course, that have made the story of spaceflights, but NOT scientists, researchers, engineers, etc.<br /><br />which kind of "science" these (very specialized pilots) may do on the moon?<br /><br />they will act as well-trained "human-robots" that will follow the given istructions with only a few changes<br /><br />also, the most depressing figures of the next 20 years moon exploration are the 15 weeks of TOTAL moon exploration time (the "net" time is less, since astronauts must sleep...) made with ONLY 48 non-scientists in TOTAL<br /><br />(around) 15 years without see NOTHING of moon, and, after, only (around) 5 years with "SO MUCH" exploration!<br /><br />it's like move a giant iceberg to New York only to have fresh icecubes for a Pepsi<br />

 

[josh_simonson]

Here's a bit under things to do at the cape:<br /><br />Astronaut Hall of Fame (NEW)<br />Located six miles west of the main Visitor Complex, the Astronaut Hall of Fame is Kennedy Space Center Visitor Complex's newest attraction. The Hall of Fame features the world's largest collection of personal astronaut mementos, plus historic spacecrafts, hands-on activities and astronaut training simulators. Sit at a mission control console, take a virtual moonwalk and feel the pull of 4 Gs in the G-Force Simulator. <-----------<br /><br />An amusement park ride at KSC exposes the general public to the same G forces as would occur in CEV launch and landing. 4G hardly closes the moon missions to all but 'the right stuff'.

 

[gaetanomarano]

<br />do you really believe that "general-public-like" astronauts will go on the moon?<br /><br />do you remember the Apollo astronauts?<br /><br />do yo remember their "science" work on the moon?<br /><br />open the box with the laser-reflector, open the box with the lunar-earthqakes-detector, open the box with the rover, travel to this place, make ano hole in the surface for sample, etc. etc. etc.<br /><br />a work good for FedEx... move this box, send this box to this place, etc.<br /><br />probably this time a few "seats" will be for international hosts... a russian captain, an italian lieutenant, an french top-gun and (to be politically correct) one astronaut from africa, one from asia, one from latin america, some women and a cherokee...<br />

 

[telfrow]

<font color="yellow">do yo remember their "science" work on the moon?</font><br /><br />Yes. <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[gaetanomarano]

<br />no... the moon-science was made on earth... before and after the missions<br /><br />astronauts was only box-move and box-open people that follow instruction trained on earth... like human-moonrovers!<br /><br />TRUE scientists are peoples that don't receive or accept orders and DON'T FOLLOW INSTRUCTIONS... they THINK and DECIDE with THEIR MINDS each day, each hour, each minute, when, where and what to do!<br /><br />how much TRUE scientists we will see on the moon in 2020?<br /><br />I think half-half-dozen (to be optimist) but (probably) ZERO (if the NASA's %-makers will discover that a CEV flight may have too much "G" and a moon landing too much risks...)<br />

 

[josh_simonson]

>do you really believe that "general-public-like" astronauts will go on the moon? <br /><br />Yep. A geologist went last time. With more seats they can be more flexible - but they will need a couple professional astronauts as well so that if something goes wrong there will be well trained people on hand to handle it.<br /><br />My point was the 4Gs is safe for the general public on an amusement park ride, so it will be safe for the vast majority of people to launch and land in the CEV. <br /><br />If you want to change the discussion to wether the astronauts chosen are of military or scientific backgrounds, you should start a new topic since that has nothing to do with the premis of this topic.