CEV: Why not a Delta booster?

[ace5]

Why not use Delta in its most powerful versions to lanch the CEV vehicle?

 

[mikejz]

Two come to mind<br /><br />1) Political reasons: Keeping the SRBs flying helps Nasa with getting the right politicians the right pork. Also keeping the SRBs helps make the HLV less cancellable. <br /><br />2) Do you want to put you butt onto this rocket? <br /><br />

 

[radarredux]

> <i><font color="yellow">Why not use Delta in its most powerful versions to lanch the CEV vehicle?</font>/i><br /><br />I think the CEV's recent resizing has made it more compatible with a wider range of other launchers. I think this was part of Griffin's original vision too. This is from the Planetary Society's report (co-written by Griffin before being appointed to NASA):<blockquote><font class="small">In reply to:</font><hr /><p>Several foreign launch systems can provide essentially the same level of medium-lift capability as Atlas and Delta. Under the current political environment, Ariane V launches from Kourou, Proton operations at Baikonur, and Sea Launch Zenit flights from the Odyssey platform in the Pacific are the most readily available options for CEV-class missions. Ariane V offers the fewest regulatory impediments to U.S. users, and it is reasonable to suppose that any French or European participation in the Moon-Mars initiative will feature a role for this launch system.<br />...<br />If political constraints can be resolved favorably, several additional international launch options would become available for exploration applications. The Chinese Long March (Chang Zheng) family has a proven track record that now includes the safe launch of a human space mission. Several current and future Long March vehicle configurations appear to have more than adequate performance for CEV-class missions, and it is likely that their prices would be competitive with those of Western launch providers.<p><hr /></p></p></blockquote></i>

 

[john_316]

Most definately I would ride this bad boy... It has more launch capacity than the SRB derived CLV. It could also launch the 5.5 meter variant of the CEV instead of the 5 meter version for SRB.<br /><br />But the assumption is correct. Some Mormons in Utah are behide keeping the SRB alive. Personally I think the HLV should be a clean sheet and not Shuttle derived. RS-68 motors are proven and reliable. If anything institute the RS-84 or a modified Kerosene-O2 motor for HLV.<br /><br />Pork in the barrel is not always a good thing......<br /><br /><br /><img src="/images/icons/smile.gif" /><br />

 

[mikejz]

I refer to the hydrogen burn-off that a Delta IV does during ignition. I have a VERY strong feeling that there will eventually be a pad explosion from this.

 

[gunsandrockets]

The chicken and egg mystery of the CEV<br /><br />Which came first the chicken or the egg? That sums up the mystery of how NASA decided the booster for the CEV. According to documents NASA has released, the 20 tonne payload of the Delta IV booster is too small to launch the 23 tonne mass of the CEV. But then when you read those same documents about the CEV you discover the CEV was enlarged to fit the expected 25 tonne payload of the favored shuttle derived solid rocket booster!<br /><br />There are two primary factors why the original CEV design masses 23 tonnes, one is having enough propellent for 1.7 km/s of delta vee to fit the NASA plan for moon travel, and the other factor is the size of the crew module. Since the original crew module of 5.5m diameter is so large, it masses over 9 tonnes! To push around that much mass by 1.7 km/s, it takes a service module massing over 13 tonnes to carry enough propellent. To keep all this in perspective the orginal Apollo capsule massed less than 6 tonnes and the entire Shenzou spacecraft including it's service module masses less than 8 tonnes. <br /><br />The current mass of the CEV is in question because now NASA says it is scaling the size of the crew casule from 5.5m diameter down to 5m diameter, but the propellent may change from methane to something less efficient and therefore more massive. The bigger mystery is why NASA decided to select such a massive sized capsule in the first place. According to NASA documents the CEV is primarly designed to fit into a lunar flight plan which has the crew spending most of their time during the lunar mission with full access to the lunar surface access module (LSAM). The LSAM by itself has a very large crew space, so why does the CEV capsule have to have 2 to 3 times the living space of the original Apollo capsule?<br /><br />Even though the CEV has a larger crew size than Apollo, there's no good reason why the CEV capsule couldn't have been designed only slightly larger than tha

 

[subzero788]

I agree that the 5.5 m CEV would have unnecessary large, but I think the current 5m design is required. Perhaps on a lunar mission a CEV of less than 5 m diameter could comfortably accommodate a 4 man crew when combined with the large LSAM volume. But you forget that the CEV will also have to accommodate 6 crew for around 2 days to trips to the ISS. That's a tight squeeze for a capsule of 4 or 4.5m, as you appear to be suggesting. <br /><br />NASA should have stuck with the requirement for methane propulsion to reduce the weight (among other benefits) but If it's going to blow their budget or slow down their journey back to the moon, I'm all for going with alternatives.

 

[gunsandrockets]

"Perhaps on a lunar mission a CEV of less than 5 m diameter could comfortably accommodate a 4 man crew when combined with the large LSAM volume. But you forget that the CEV will also have to accommodate 6 crew for around 2 days to trips to the ISS. That's a tight squeeze for a capsule of 4 or 4.5m, as you appear to be suggesting."<br /><br />Actually for ISS missions the CEV will only have a crew of three, not six. The only proposed use of the CEV with a crew of six involves extremely speculative Mars missions with the CEV crew module occupied for less than a week at a time.<br /><br />And as for how much size is enough, during Gemini missions the crew stayed as long as two weeks in the tiny capsule.

 

[ace5]

"1) Political reasons: Keeping the SRBs flying helps Nasa with getting the right politicians the right pork. Also keeping the SRBs helps make the HLV less cancellable. "<br /><br />So we can assume that the SRB use is more political than technical?<br />I think Delta is safer than an SRB, simply because Delta can be turned off in the case of a launchpad failure.

 

[space_dreamer]

SRB use is more political than technical<br /><br /> – Yes, I would hate SRB& CEV combo if that all it was, but its part of the SDHLV plan. Keep the manned transport cheep and unimpressive, while having as much similarity with the SDHVL design so it’s hard to cancel it.<br /><br />Once the SDHLV is built and the moon missions are under way then the liquid flyback booster designs could be dusted off to replace the SRBs! The new launchers could end up with a proper reusable flyback first stage! <br /><br />

 

[j05h]

>Many reasonable people (including myself) think that an HLV, though really nice to have, is a mistake for NASA to expend it's limited resources on.<br /><br />Yes, they could build a lot of 20ton deep-space modules with the money being spent on CEV/HLV. They could use those billions to develop Zubrin's Triangle Economy (Earth-Moon-Mars) but instead are spinning their wheels and filling someone's coffers. Bob Truax made a salient point years ago: whatever the size, if you build orbit-capable rockets, they all cost about the same to design and begin building. So, instead of making a non-reusable 90-ton SDHLV, they could be building SeaDragons or massively responsive 5-ton spaceplanes. Or buy already available flights on under-utilized (EELV, other) rockets. Use the savings to build the fuel depots, etc that are needed to open the solar system.<br /><br />Their other choice is likely to be irrelevance: focusing on making new versions of extant capabilities (LEO access) is taking away from what NASA does better than anyone, that is deep space exploration. There are plenty of rides to LEO, but NASA is the only organization in the world with the knowledge to explore like that. Instead of capitalizing on it, they are squandering their resources to replicate capabilities. <br /><br />I really think the Bush VSE and Dr. Griffin's posting are great. In them is a not-so-hidden challenge to the Primes, the startups and the entrepreneurs. If we in the private sector can offer these services sooner, they will use the services instead of building their own. If SpaceHab (for instance) built their common-module 20-ton units, NASA might buy them instead of developing the EDS. So, we have to put up or shut up as well. <br /><br />There is a LOT of money to be made in space application hardware, we just need to figure out what is do-able for starters. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[llivinglarge]

Isn't a pad explosion possible with the Shuttle SRB?

 

[drwayne]

"Explosions" of SRB's on the pad do not strike me as likely.<br /><br />Case burn through or joint leakage are certianly possible, though they are not in the "explosion" category.<br /><br />Of course, you can get some interesting and - energetic discussions going on exactly what the term "explosion" means in the context of the current.<br /><br />Most of the energetic failures on the pad that I am aware of have been liquid systems.<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]

Here is my question? Ok maybe more...<br /><br /><br />When the SRB is fitted with a second stage and CEV will the new added weight effect the performance of the SRB and if so how much so will it effect it as all the weight will be on the SRB in a vertical configuration and not on an offset configuration such as the ET?<br /><br />Wont the SRB have to have a stronger "strongback" and thicker walls to support the weight of the CEV and upperstage without a major drop in performance? Or will this matter little?<br /><br /><br /><br /><img src="/images/icons/smile.gif" /><br /><br />

 

[qso1]

The added weight will affect the performance of the SRB but not enough to prevent it from doing the job of getting the CEV to orbit. Otherwise, this configuration would not even be considered. Vertical config is actually less stressful for the SRB and the SRB casings are something like 1 inch thick steel if memory serves me. Most liquid rocket stages are thinner aluminum skinned. <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>

 

[radarredux]

> <i><font color="yellow">So we can assume that the SRB use is more political than technical?</font>/i><br /><br />Griffin and others in the Planetary Society suggested using the SRB well before Griffin became part of NASA. So while I am sure there were political issues, I think saying they it was the only issue or even the primary issue is probably too strong.<br /><br />There are a couple of (non political) advantages to using the SRBs including:<ol><li>the changes to get the SRB ready for the CLV were probably smaller than the changes to getting any other booster ready<li>the SRBs have had roughly 100 flawless launches since Challenger making it probably the most reliable rocket in the US inventory<li>by contrast, the US has virtually little to no record for the EELVs capable of supporting the CEV<li>the SRBs are going to be used for the CaLV, so there may be some economies of scale in using the same booster technology in both launch vehicles<li>there is already an extensive human experience at NASA (collectively) when it comes to using the SRBs.</li></li></li></li></li></ol><br />Was the choice of SRBs politically expedient? Probably. But there are other reasons for using it.</i>

 

[edkyle98]

Delta IV Heavy would not be able to orbit the CEV without a new, higher-thrust second stage. This because CEV must ascend on a shallower ascent trajectory than the standard EELV lofted trajectory. The ESAS report said that the resulting upgraded Delta IV Heavy, which would also incorporate some additional "man-rating" efforts, would 1) cost more than an SRB-based crew launcher and would 2) be a bit less safe for the crew than an SRB-based crew launcher. <br /><br /> - Ed Kyle

 

[brandbll]

If it's for the moon why not just rebuild a new improved Saturn V? Wouldn't taht be the most logical seeing as we know they work what we want 'em for?<br /> <div class="Discussion_UserSignature"> <p><font size="3">You wanna talk some jive? I'll talk some jive. I'll talk some jive like you've never heard!</font></p> </div>

 

[radarredux]

> <i><font color="yellow">If it's for the moon why not just rebuild a new improved Saturn V? Wouldn't taht be the most logical seeing as we know they work what we want 'em for?</font>/i><br /><br />There are a couple of reasons:<br /><br />First, Congress and NASA want an American solution to reaching ISS as soon as possible after the Shuttle is retired, and the CEV + CLV provides the quickest path to that solution. By the time a new Saturn was built it would be close to time to de-orbit ISS.<br /><br />Second, there was an early decision for safety reasons to separate cargo from crew when launching to LEO. So from the get go, there was always a 2-launch strategy. A Saturn-class vehicle could still be used to launch the EDS and Lunar Lander into LEO, but NASA would still want to launch the crew on a separate vehicle.<br /><br />Third, the cost and time to build a Saturn versus the current plan is much higher. For example, the current plan still uses many of the machine tools used to construct Shuttle components; all this would be abandoned and new tools would need to be created for a Saturn rocket. As a specific example, NASA has already purchased the material to be used in the CaLV fuel tank because it was originally planned to be used for the Shuttle ET but won't because of the Shuttle's 2010 retirement.</i>

 

[mattblack]

To answer many of the newer poster's questions, go to this link and read the final ESAS reports. I know some of it is long-winded and some of you may not believe all the data, but you'll learn a LOT from reading them:<br /><br />http://www.nasa.gov/mission_pages/exploration/news/ESAS_report.html<br /> <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>