The Crew Exploration Vehicle

[trailrider]

While I don't have facts & figures for such a beast, a pair of 4-segment SRB's side-by-side would require a highly modified launch pad...UNLESS you split them apart with something the size of an ET in between! Then you'd have to mount the CEV on top of that "adapter"...which MIGHT be the second stage (ignited at altitude a la a Titan 34D/IV). Then, of course, you have to worry about separation, rather than just staging. Might work at that, but I suspect a pair of 4-segment firecrackers would generate too much thrust.<br /><br />How about this... make BOTH SRB's 5-segment, and put either 5 non-reusable SSME's or some R-68's on the bottom of an elongated ET, with an upper stage with a bunch of J-2S's. Oh, wait a minute...that's the CaLV! <img src="/images/icons/wink.gif" /><br /><br />Ad Luna! Ad Ares! Ad Astra!

 

[radarredux]

> <i><font color="yellow">a pair of 4-segment SRB's side-by-side would require a highly modified launch pad.</font>/i><br /><br />The acceleration would probably be a little intense too.</i>

 

[lampblack]

<font color="yellow">That's interesting that you use a jet engine, an airbreathing engine, for space</font><br /><br />I've been away... but I thought it was a warp nacelle. *grin*<br /> <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>

 

[ascan1984]

I cant believe they are making another manned vehicle with an SRB system. As powerfull as they are will they never learn. I am shocked at this.

 

[mattblack]

Why are you shocked? Statistically, they are the second safest manned boosters ever flown (second after Soyuz). With over 110 Shuttle flights, pairs of these things have effectively flown more than 220 times. One of them (once) sprung a leak but NO Shuttle SRB has ever exploded, nor will they ever.<br /><br />A five-segment version will make more than 3.4 million pounds thrust and for an Atlas V or Delta IV to equal it's performance in first stage, you'd need to cluster three booster cores to do the job. Even though these vehicles would have at least 15% percent superiority in specific impulse over an SRB-derived launcher, you still need a lot of thrust with the LOX/LH2 & LOX/Kerosene rockets. And for the first two minutes of flight that the SRB operates in, ISP ratings don't mean quite so much. Also, with a suitable escape system, it doesn't actually matter if the crew is launched on a solid or liquid booster. (Though admittedly, the Abort constraints from the Sold CLV will prove challenging to define). <br /><br />I say; use the 5-segment CLV launcher until the Lunar-Mars CaLV is ready for actual funded development (to preserve the tooling and expertise), then switch the CEV launcher to an EELV-derived (Atlas V my choice) after that with the lowest possible numer of changes, beyond a more powerful upper stage engine. Then you'd never have to launch crews on a solid rocket again. The Solid CLVs might then be preserved for cargo-CEV flights only. <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>

 

[barrykirk]

My problems with the SRB's have nothing to do<br />with reliability.<br /><br />How much do they cost?<br /><br />And if your re-using them, which should be a major<br />consideration for a 1st stage. How much does it<br />cost to refurb them for the next flight.<br /><br />Compare that to a LOX/RP1 solution.<br /><br />I've never seen any direct cost comparisions that say.<br />This is the cost per Kg of thrust for an SRB versus the<br />cost per Kg for a LOX/RP1 solution.<br /><br />Now, I understand that we are comparing Apples to<br />Oranges. Because if you double the burn time of a SRB<br />it's cost almost doubles. Where the liquid solution has<br />very little cost increase for doubling the burn time.

 

[mattblack]

You raise interesting questions and it'd be good if someone could uncover a true comparative study or set(s) of data. <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>

 

[j05h]

>SRBs... And if your re-using them, which should be a major<br />consideration for a 1st stage. How much does it<br />cost to refurb them for the next flight. <br /><br />Another aspect is the time involved between reflights. In theory, a LOx/kero first stage can be landed, refueled and reflown immediately. That would be true "airline" efficiency. Obviously, solids (and hybrids) have the ability to be shelf-stored allowing for many launches in a short span, and current SRB casings are refurbished but at no true cost savings. This is much different from re-using the vehicle as we would a jet or prop driven aircraft, which a flyback or other reusable booster resembles operationally. <br /><br />On the CEV, it should be a capability that NASA sets a price for, or that is posted alongside vehicle development. I'm repeating a theme here, but setting a price ($100,000,000/astronaut 6months in LEO or $44mil like Soyuz) would see American suppliers ready to serve that market much much faster than all this CEV development is taking. It costs them nothing except a one-page prospectus. Having a set price for transport would allow companies such as t/space to aquire loans, as it would be an assured market. <br />They can look at the price, the cost of their development and know that (barring failure) they can actually repay the loans. <br /><br />I just got back from ISDC, and found a critical distinction between NASA/Primes and the newspace companies: the newspace companies are building and flying hardware now, even if it's limited, while CEV etc seem to be drowning slowly. There were great VSE viewgraphs, and the various Challenges NASA has posted are great incentives, but they don't seem to have any flying hardware. Compare that to 20+ launches (of wide range) that will happen at the XPrize Cup 2006, or that Dave Masten can go from napkin to 100lb thrust methane engine in 6 weeks. As always, I'm not "dissing" NASA, I just want to know where the hardware is. The money spent on the <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[qso1]

Since your inviting comparisons:<br /><br />JO5H:<br />Another aspect is the time involved between reflights. In theory, a LOx/kero first stage can be landed, refueled and reflown immediately.<br /><br />Me:<br />When you say in theory, thats correct, and this remains an untested theory which even if doable in a cost effective operational sense... immediatly would probably not be part of the equation in reality. This idea dates as far back as the initial liquid booster proposals for shuttle and I believe it was even considered for the Saturn-V. Even the Russians claimed the Energia liquid booster rockets were recoverable but never actually recovered them although Energia did fly only twice. At least one technical hurdle is protecting the thrust chambers and engines from salt water for sea going recovery.<br /><br />JO5H:<br />I just got back from ISDC, and found a critical distinction between NASA/Primes and the newspace companies: the newspace companies are building and flying hardware now, even if it's limited, while CEV etc seem to be drowning slowly.<br /><br />Me:<br />What manned hardware has flown besides the Rutan vehicle and what companies are already flying hardware? Any of it manned orbital?<br /><br />JO5H:<br />Compare that to 20+ launches (of wide range) that will happen at the XPrize Cup 2006,<br /><br />Me:<br />Is any of the "X" prize cup stuff flying into space, low orbit?<br /><br />JO5H:<br />can go from napkin to 100lb thrust methane engine in 6 weeks.<br /><br />Me:<br />Can he develop a working methane engine of 50,000 lbs thrust in six weeks?<br /><br />JO5H:<br />As always, I'm not "dissing" NASA, I just want to know where the hardware is.<br /><br />Me:<br />The program is barely two years old. No hardware can be expected for a couple more years.<br /><br />JO5H:<br />There is a strong possibility that a US contender will be available against whatever vehicle a surviving CEV program produces.<br /><br />Me:<br />This is certainly possible with private enterprise in the wings <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[scottb50]

I think having to have a NASA Navy to retrieve the SRB and the record of re-usability that I've heard about makes wings, for a first stage, look a lot better. Solid rockets and liquids could be used with fixed SRB housings. Use the liquids for steering and fixed nozzles on the SRB's. <br /><br />Pull off the Nozzle Segment, pull out the spent casings, stack new propellant Segments in the Nozzle Segment and lower the vehicle down over them. Even with inspections of the housings it could be done in a few days.<br /><br />To save money use the Shuttle Launch Platforms, lower the empty first stage over the SRB Nozzles and stacked propellant segments and add the payload before or after transfer to the pad.<br /><br />A CEV, with an attached, restartable upper stage could be a payload or a winged first vehicle, for a more comfortable return, could attach to the same First Stage. <div class="Discussion_UserSignature"> </div>

 

[j05h]

(doubled-up reply to qso and scott)<br /><br /> />When you say in theory, thats correct, and this remains an untested theory which even if doable in a cost effective operational sense... immediatly would probably not be part of the equation in reality.<br /><br />Immediate reflight of liquid fueled restartables has happened, with the EZRocket plane. It's LOX/Methane IIRC, but is liquid fuel. DC-X had a very short turnaround as well. <br /><br /> />What manned hardware has flown besides the Rutan vehicle and what companies are already flying hardware? Any of it manned orbital? <br /><br />SpaceX "Dragon" is manned orbital, but on the back burner until they get Falcon flying regularly. SpaceX is sort-of flying, Armadillo, t/space and airlaunch have conducted recent drop tests. The XCOR EZRocket flies, is manned, has set several records and is the basis for the rocket-racing league craft. So, yes, there are manned vehicles being built and tested outside NASA. <br /><br /> />Is any of the "X" prize cup stuff flying into space, low orbit? <br /><br />Not yet. They'll probably have one of the old XPrize competitors fly in the next few years, but are plannign on flying the first XRacer this year. It's not space, but it is a rocketplane. They want to have orbital and altitude races eventually. the tech isn't there yet.<br /><br /> />Can he develop a working methane engine of 50,000 lbs thrust in six weeks? <br /><br />Could Masten do that? Not sure, but wouldn't put it past him. I do know that Pratt, Boeing, etc couldn't even get the spec done in that time. We have become ruled by paperwork. <br /><br /> />The program is barely two years old. No hardware can be expected for a couple more years. <br /><br />I disagree. I think that we should have had drop tests already, and it puts shame on NASA and the Primes that they don't have the guts to do it. Push a plywood model out the back of a C5 and see what it does! It's been 2+ years since VSE was announced, but this has been an ongoing issue <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>