SRB-derived CEV

[dreada5]

http://www.thespacereview.com/article/226/1<br /><br />There are a number of advantages to using tried-and-tested SRBs with a liquid second stage, but:<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>There are technical issues that a SRB-derived launch system would have to address, notably the development of a new upper stage. However, in the long run the bigger challenges that an SRB-based launcher might have to face are perceptions: that the SRB is an old technology, best left to the past; that solid-propellant motors like the SRB, which can’t be turned off once ignited, are unsuited for manned spaceflight applications; that the EELV will need the anticipated volume of CEV launches to lessen the cost burden of the two vehicle programs on NASA and the Defense Department. Successfully handing those perceptions will depend on the champions the SRB design wins within NASA and industry. In a brief interview after his Mars Society presentation, Horowitz admitted that industry was skeptical about the idea at first but has since started to warm to it. There’s certainly a lot more work that Horowitz and others will have to do, though, to gain converts to an SRB-launched CEV.<p><hr /></p></p></blockquote><br /><br />What do you guys think??

 

[najab]

My initial reaction was the same as most people when presented with this idea: "You wanna do <b>what</b>?!!!" However, after some thought, my disbelief at the insanity of the idea gave way to amazement at it's bold and - dare I say it - brilliant simplicity.<p>The SRB is human rated as a result of its origin as a component of the STS. It is safe - in 224 launches there has been one failure, and that was with an obsolete design. It is cheap, especially if you don't bother with recovery and reuse. It is incredibly simple - as are all solids. Most importantly, its is available <b>today</b>. A man-rated version of either EELV is a long way (and a lot of money) down the road.<p>I've gone from an skeptic to a believer, so much so that I would enthusiastically volunteer for the first ride.</p></p>

 

[mattblack]

I cautiously like the idea, because it already exists to an extent, is "man-rated" and would give the best payload for the buck. Plus, if it was made into a 5-segment rather than 4, it would also go well with an E.T. and 2-or-3 RS-68 engines for a future Shuttle derived HLV.<br /><br />Also, for a C.E.V. alone launch to L.E.O. for example, it could be made without a segmented structure (or at least fewer segments) for strength and 'cheapness', like the old Titan 4 boosters. <br /><br />But best of all, as long as the C.E.V. had a proper Apollo-style escape system, it would not matter if it were a solid or liquid booster for a manned craft. <br /><br />NOTE: The picture is from someone's earlier post. Thanks, whoever that was!! <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[najab]

Of course, the other reason I've fallen in love with this idea (always a bad sign) is that it absoultely <i>reeks</i> of Apollo-era "Yes, I realise it's impossible, but I <i>still</i> want it on my desk on Monday!"<p>What a ride! Mach 18 at 20Gs - the OSHA-approved NASA of the 1990's would <b>never</b> consider it for an instant. This is (at the risk of sounding Arnold-esque) not a girlie-man's rocket! This is a "40,000lbs to LEO for $100M and don't spare the horses" rocket.<p>Forget "enthusiastically volunteer", I'd <b>pay</b> for a ride like that!</p></p>

 

[dreada5]

I agree with both of you guys. I just wonder why NASA hasn't embraced it more. I know Boeing and Lockheed don't like the idea, but their approaches are likely to take significantly longer, be more complext and cost more. So again, I hope NASA conducts a serious feasability assessment on the idea.

 

[nacnud]

I think it's a great idea to after the initial you WHAT! However I'd also like to see the CEV capsule thingy modelled along the lines of an updated Big Gemini concept where the one ship could be launched off various rockets (EELV if they ever get man rated, Arian 5 etc) and it to be a cheep robust get people to orbit and back and that’s it kind of vehicle. <br /><br />The extra modules to go to the moon etc can come later, get an alternative to the shuttle for ISS stuff ASAP so we can get some use out of it before its life runs out.<br />

 

[bobvanx]

>Mach 18 at 20Gs<br /><br />Is that what the thrust vector works out to? Whoof, what a great way to make chunky salsa out of humans.<br /><br /><br /><br />Stray thought: You know how a concrete bridge works? The elements are pre-tensioned to giant compressive forces, so that the weight of the cars, trucks, airplanes is really insignificant to the concrete structure.<br /><br />I wonder if a water-filled, highly pressurized (say, to 600m depth equivalent) crew quarters would protect humans from crushing G forces.<br /><br />The mass of the water is an obvious trade-off.

 

[najab]

><i>Note there is apparently no full range of safe abort modes with the SRB burning.</i><p>Admittedly this is less than optimal. But there have been worse systems out there. A Gemini-Titan abort attempt after ignition would have been bad news for the first minute or so of flight, Shuttle is bad news until SRB sep and Vostok/Voshod would have been dicey as well. The key is to make sure that you never need to attempt an abort.<p>I'd rather ride a SRB which was designed to be man rated, than a Delta/Atlas that had the man-rated designation slapped on as an afterthought.</p></p>

 

[dreada5]

Another reason why I like the SRB concept is because a lot less work is required. I think the way aerospace development work usually goes, that 2014/2015 is gonna come around awfully quick. They could better use that time looking at how to get to the lunar destination once the SRB gets them to LEO.

 

[najab]

><i>I'm assuming it burns from the bottom to the top. Is that correct?</i><p>No. The SRB grain is hollow down the centre, all the segments burn at the same time.</p>

 

[nacnud]

I think the SRBs burn from the middle out, its the masive surface area which gives them such large thrust.

 

[mikejz]

I wounder why Morton-Thiokol does not try and make a standard booster out of the shuttle SRB? Afterall, if it did it would compete nicely with EELVs. Forget CEV, give Nasa something you can show already working.

 

[wvbraun]

Ok, I have to admit the SRB-proponents have some very good points. Still I'd like a liquid fueled booster better. Let SpaceX develop a heavy version of their planned Falcon V rocket.

 

[mikejz]

I'm not sure SpaceX would be able to bring anything like that to market in anything less then 10 years. A heavyer lift rocket would mean that they develop a new main engine. Plus, they already spent all that money have don't even have one launch to show for it yet. I say wait until the Falcon V is proven, then maybe expect them to work on the next project. Intresting note however, I don't see why SpaceX could not develope a 'Big G' style capsule for the Falcon V and contract out flights to the ISS. <br /><br />Speaking of SRBs--Why stop at a single SRB for the CEV--Cluster 5 or 6 and you have a booster in the Saturn V category.

 

[drwayne]

Here is a cutaway of the SRB. The hollow inner section is the burn surface of the booster.<br /><br />http://history.nasa.gov/rogersrep/v1p56.htm<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]

Sorry, I rushed to find one, and did not find the best...<br /><br /><img src="/images/icons/frown.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>

 

[Aetius]

The more I look at this as a layperson, the better an idea it seems.

 

[drwayne]

I understand. I just should have taken more time to find a better one.<br /><br />The shape of the grain is a really interesting art.<br /><br />The fact that the burning surface is so large accounts for what many at first wonder about - the fact that a relatively low (vis'a'vis liquids) Isp fuel/oxidizer can create such large thrust values.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[john_316]

This is for anyone.<br /><br />Can the SRB handle the Apollo era Command Module and Service Modules weight load to LEO or even 120 nm orbit?<br /><br />Would it require 5 segment boosters in addition to a liquid fueled upper stage? <br /><br />Can a Centaur upper stage handle the weight of the same Apollo era CM and SM?<br /><br />The new CEV will obviously be lighter than the Apollo CM and SM but will it be the same size and diameter with a fairing of 5m or less? Or can we get a larger one which will hold a larger crew at the same weight?<br /><br />I was thinking that the CEV would install the para-foil envisioned on the OSP? Any takers?<br /><br /><br />As mentioned earlier about 2 SRBs, can 2 SRB's with lets say a Delta or Atlas central core stack handle the weight of the apollo era CM and SM as well to LEO or GEO?<br /><br />The reason I mention Apollo is becuase I sincerely believe they will use those diagrams and prints to come up with the new CEV. Accept it will be lighter and more robust. Hopefully be able to carry a crew of 5 to 7 as required as well.<br /><br />Any ideas?<br /><br /><br />

 

[mikejz]

I'm not so sure about that---look at all the DC-3s still flying!

 

[drwayne]

As nacnud mentioned early in the thread, variants of the Gemini design might be more interesting that Apollo.<br /><br />Interesting article from a favorite source of mine on interesting aspects of Gemini vis'a'vis Apollo<br /><br />http://yarchive.net/space/apollo/gemini.html<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[john_316]

What I mean is the mass, the size, and the crew arrangements not the implimentation of 50-60s era electronics and stuff.<br /><br />I mean the weight was very high then. I imagined if we used the same scales of the Apollo we can build it with less weight at the same size with newer compounds, polymeres, and fabrication. <br /><br />But what I am saying is can we do that and or use the same original weights with a larger CM and SM? twice the size and or arrangements with a larger crew or do we have to stick to under 32,000 lbs like they intented?<br /><br />

 

[najab]

I assume you read the article, they propose rebuilding the J-2 rather than using a SSME. I think this might be a better idea because the J-2's should be cheaper to produce than a restartable SSME.

 

[najab]

But wouldn't the SSME have to be running at way less than full thrust? I can't do the calculations because I don't know the conditions at SRB burnout, but I suspect that a SSME would have to be throttled <b>way</b> back to keep the acceleration low - which would be a waste of its capacity.

 

[najab]

Might it not be better then to take a lower performance engine and run it at full throttle (and maximum efficiency) most of the way? Rocketdyne of course would want to use the SSME since that's a much more expensive engine, plus they get a fat development program to make it air-startable.