Shuttle Derived Sillyness Part I: Getting Shafted by "The Stick"

The Stick
Before becoming the current NASA administrator, Griffin had been part of a group sponsored by The Planetary Society to study how to extend human presence into the solar system. In the report that group put together, one of the things discussed was a potential alternative to the Boeing and Lockheed operated EELVs for launching NASA’s planned Crew Exploration Vehicle. This idea, referred to rather affectionately as “The Stick” by it’s promoters at ATK and NASA, consists of basically stacking a large LOX/LH2 stage on top of one of the solid rocket boosters that currently are used on the Space Shuttle, with a capsule on top. The picture on the right is from ATK’s glitzy new propaganda site, SafeSimpleSoon.

When it first came out, I thought this was a rather silly idea, but figured it wouldn’t get very far anyway. After all, who in their right mind would want to fly on what is little more than the worlds biggest firecracker? Unfortunately, with ATK’s bigtime marketing effort, and with Griffin’s being selected as the new NASA administrator, this idea has been getting a lot of attention lately. In fact, if recent rumors have any connection with reality, it looks like Griffin has more or less made up his mind that he wants to do both “The Stick” and a massive, 120-ton to LEO “In-Line” Shuttle Derived Booster.

I have several problems with “The Stick”, and with the apparent decision to go with it, and I want to spend the rest of this article looking at a few of them.

  1. One of the biggest things that bugs me about The Stick is the fact that NASA appears to be changing the CEV requirements specifically to favor The Stick over its currently existing rivals. When the request for proposals on the CEV originally came out, the plan was for the CEV to be able to deliver 4 people to orbit, and the spacecraft mass was supposed to be limited to about 20 tons or less. Since ATK started it’s marketing blitz, all of the sudden NASA needs 6 astronauts per flight and the CEV has crept up to 30-35 tons. Since the CEV is now this big, we are told that it can’t possibly fly on the EELVs without extensive upgrades, but The Stick can do it! How convenient.

    Big GeminiBut does it really need to be this big? I mean, for comparison, the Big Gemini spacecraft proposed by McDonnell-Douglas as a follow-on for their succesful Gemini program would have weighed in one version 15,600kg carrying 9 people to orbit and 2500kg of cargo. The vehicle would have had about the same volume envelope as the Apollo Command Module, with a 3.9 meter diameter at its base. It included a reentry module with both a crew section and a passenger section, a launch escape system, a retrograde module for delivering the reentry burn, and a Manuevering/Cargo module with a docking adapter, cargo space, and a pressurized pass-through door that could allow for shirt-sleeves transfer of cargo to other vehicles or a space station. A 6-man version of this, with no cargo would probably weigh in around 8-tons, which would make it small enough to launch on one of the Atlas V or Delta IV versions that have no solid strapon boosters. And that is with 1960’s era technology!

    As a more recent data point, a good friend of mine out here in the Bay Area, George Herbert, is starting up a company, Venturer Space that is trying to develop a 5-6 man capsule for the America’s Space Prize that he is designing to be flyable on a Falcon V. That’s only 6 tons. One can handwave him away relatively easily so far, since he hasn’t built or flown any hardware yet, but from what I’ve seen of his work, it appears valid. More importantly, the guys who were pushing for the Big Gemini had built and flown manned orbital spacecraft only shortly before making this proposal, and had a very good feel for what was reasonably possible and what wasn’t.

    NautilusNow, this may not seem related, but follow with me for a second. The proposed inflatable Nautilus module that Bigelow Aerospace is developing, is expected to weigh in at 23,000kg. It provides about 330 cubic meters of useable volume, a docking adapter, and enough life support equipment to function as a self-supporting space station, if I’m understanding the articles correctly. The reason why I bring this up is that when you add the 23 tons to the 15.6 tons of the 9-passenger Big Gemini, you come out with about craft that weighs 39 tons, and can support 9 people with luxurious accomadations for long durations with 2500kg of cargo to boot. If you scaled it down to a 6-man version, you could likely keep the mass of the whole system to less than that of the proposed NASA launcher, in spite of the fact that you’d be flying both a capsule and a space station every single time you fly to orbit!

    The thing that gets me about this is that one of the reasons why they are pushing for the big in-line booster is so that all the translunar equipment and long-duration facilities can be launched in a single-shot without having to do on-orbit assembly. So if The Stick is only launching a 6-person earth-to-orbit capsule, with minimal cargo, and only short-duration life support facilities, why does it need to weigh so much? The only reason I can possibly see for making the capsule so heavy is if they are including long-duration habitation facilities, but the fact is that they don’t need such for just launching people or cargo to the station or to a waiting translunar stack. If you already have a flying space station for a CEV, why do you need such a big heavy lifter to put up a lander and a transfer stage? Something doesn’t add up.

    Now NASA may have a perfectly good reason for why they need it to weigh so much, but it looks to me at least like someone is trying to get the numbers fudged to match their predetermined conclusions. I’m not saying that to accuse Griffin of any sort of malfeseance, but merely saying that as nerds it’s easy to get so excited about a given technical solution that its easy to start ignoring contrary evidence or start making unwarranted assumptions or unneccessary requirements that lead to your preferred solution.

  2. The next major issue I have with The Stick is the bait-and-switch that appears to be going on. In making their clam that The Stick would be Simple and Soon, ATK made their original case using a standard, 4-segment SRM like what is used on the Shuttle, with no real modifications, and then stack a modern version of the S1C stage on top of it. Supposedly that means that almost everything is right off-the-shelf, and would be quick and easy to put together. The problem is that in NASA’s attempts to grow the CEV big enough to justify the solution they want to push, they’ve outgrown the capacity of that setup. Now they’re talking about a 5-segment SRM with an SSME driven upper stage. I think I’ve even heard from someone that the SSME used would have a nozzle extension. While the 5-segment SRM has been ground fired I think, it hasn’t to my knowledge been ever flown on the shuttle. I could be wrong on that, but I don’t know. I also don’t know if the SSME has ever been tested with a nozzle extension like that. Not to mention that throwing away an SSME with every crew launch is likely to get spendy.
  3. Another issue I have that is related to the first two is the glossing over of the development work that would need to be done in order to actually bring The Stick into operation.

    In order to adapt the SRM for use as a first stage, the burn profile for the booster will likely need to be changed. While this isn’t too rediculously tough, it will require redesign of a lot of tooling, and a lot of validation testing and possibly some flight testing to develop. More importantly, as several people have noted on usenet, the Shuttle SRMs can provide some pitch and yaw control, but no roll control. Roll control would thus need to be provided either by adding some sort of roll control package to the booster itself, or as part of the upper stage. Once again a straighforward piece of engineering, but a piece of engineering nonetheless.

    Additionally, they talk about resurrecting the J-2 as though it wouldn’t take much work at all. The reality though is that many, if not most, of the original subcontractors for the J-2 no longer exist. Some of the fabrication techniques are obsolete, inferior, or much more expensive than modern techniques. Many of the sensors would need to be replaced, and should be replaced, by lighter, cheaper, and more reliable modern sensors. New tooling would need to be made, the pumps and engine would need requalification. Even if you stuck faithfully to the old J-2 system and only update those parts that were absolutely obsolete and require updating, it would still take a lot of time and money to requalify those systems and get them up to flight worthiness. If an SSME is modified, that may be quicker, but would likely still require some additional testing work if they do a nozzle extension. And though the SSME is available on the shelf, it’s a really expensive, and not really designed for in-space use. You really don’t need a 3000psi chamber pressure for an upper stage engine. There are other possible engines that could be used like the RS-68, that might not actually require as much development, but the engines suggested so far would require a lot of work.

    Lastly redesigning a huge LOX/LH2 stage again from scratch is also a time-consuming, non-trivial, and expensive process. This stage would be much larger than most LOX/LH2 upper stages that have flown in recent history. You’re basically redesigning half of a Delta IV.

    Lastly, you’d have to make substantial modifications to the launch facilities there at the Cape. The Stick is much taller than the current shuttle stack, and a very different form factor. Redesigning the launch pad and mobile transporters is definitely doable, but will cost money and take time.

    Lastly, the whole thing would need at least a few flight tests to prove itself out before it could be pressed into service.

    The only way that ATK can get away with trying to claim that this is Simple and Soon is if they can get NASA to force the CEV mass to be so heavy that it can’t be flown on Delta IV or Atlas V without them doing a bunch of redesign. But as I’ve already discussed, their reasoning on the mass requirements doth stink.

  4. Notice that they don’t mention anything about the cost on their site. They will need to start up a new assembly line for a very big LOX/LH2 upper stage that will be making at most 6 stages per year. If they go with a J-2 derivative, those will also be made in small quantities and require a new plant. The SRMs aren’t horrendously expensive themselves, but they aren’t phenominally cheap either. The ATK site claims that they can deliver $3000/lb prices, but doesn’t say if that includes any amortization on the development costs, or capital costs for these new facilities. It also doesn’t mention if that includes their share of the old Shuttle infrastructure that will have to be maintained for use with The Stick and the In-Line Booster. Even if it does include all that, $3000/lb is nothing to brag about. It only looks tolerable when compared to current EELV prices, and only if you assume that you have to fly some bloated CEV that requires you to fly the most expensive EELV versions. One of the reasons why EELV prices are so high is that their flight rate is much lower than they designed their pads and factories for. I don’t have the numbers on-hand, but I recall that they could produce a total of about 50 cores between the two of them per year without expanding their factories. They’re flying less than 5-6 each out of a capacity nearly 4 times that. If NASA went with a reasonable sized CEV that could fly on the Delta IV Medium, or the Atlas V 401, they could probably get much more reasonable prices. Adding another 6-10 flights per year would make a big difference for the prices the EELV companies would need to charge to actually make a profit.

    Now, being a libertarian, I can’t stand the big government contractors, but at least their vehicles exist! It’s fairly obvious that they could give better prices if there were more flights. There is already a glut of launch providers in this weight class and general price range. Why does Griffin feel that we need to add a NASA operated competitor to make things even worse? While I’d rather that the US government just leave space launch alone, I’d rather they at least not try to compete with the market and develop their own redundant system when adequate capabilities already exist.

  5. As I mentioned in my previous post, NASA wants to offer non-traditional providers a chance at some of the action by buying ISS cargo delivery services. These could definitely be done on existing US boosters, or could reasonably be done with startups like SpaceX or t/Space. However, in spite of the bloated CEV mass requirements no longer being a reasonable excuse, ATK still wants to develop a cargo version of The Stick too. There’s just no valid reason why this needs to be done. ISS cargo delivery can be done using existing or commercially developed boosters. I guess that if you’re already fixated on developing the crew version, making a cargo version doesn’t seem like that big of a deal, but it is an entirely different spacecraft that should be designed to be flyable on other boosters. Making a government funded cargo delivery vehicle that can only be flown on a government operated booster is a recipe for waste and innefficiency.
  6. Lastly, I can’t understand why so many people are so concerned with trying to maintain jobs from the Space Shuttle program. The main reason why the Shuttle program costs so much is because so many people are on the payroll. Even if the Shuttle doesn’t fly in a given year, you still have to pay the salaries of nearly 10,000 employees. Sure if you get rid of the orbiter, you can get rid of about half of those people, but now you need to add people back for processing the CEV, and soon you’ll find that what little savings could have been had from retiring the Shuttle have been completely been squandered. Sure, it’s politically easier to try and bribe congresscritters by maintaining useless jobs performed in their districs, but haven’t we learned how much of an inefficient, bureaucratic mess that is?

    We have to chose whether we’re trying to open up the solar system for human development, or if we’re trying to run welfare for aerospace nerds. NASA can’t afford both.

I think there are other points that could be made, but these are the key ones that have been bothering me.

Some people wonder why I care. I work for a commercial space company that is making suborbital vehicles. We aren’t involved with any of the contractors, and really aren’t looking for NASA money. I’d like to see us do stuff related to lunar landers or orbital launch vehicles sometime in the future, but we’re still on babysteps ourselves. Some argue that NASA’s irrelavent, that we should just let them make stupid decisions that waste money, because at least that will keep them spinning their wheels and not actively impeding the alt.space community.

The problem is that NASA’s decisions to try and do an Apollo redux does hurt the rest of us. It makes it more difficult for commercial companies to raise money, it perpetuates the myth that space needs to be hard, needs to be expensive, or requires big government agencies to do correctly.

Anyhow, it’s getting late, and I’m running out of things to say, so I’ll leave it at that for now. Comments are open and always appreciated.

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
Jonathan Goff

About Jonathan Goff

Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
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17 Responses to Shuttle Derived Sillyness Part I: Getting Shafted by "The Stick"

  1. Kelly Starks says:

    Having worked at NASA from ’81-’95 on Shuttle, station, and HQ — I have do problem at all considering Griffens sudden desire to double the CEV weight part of some weird plan. Griffen is starting to weird me out. Hes almots a NASA groupy ignoring NASAs major problems rather then reforming it. But thats for another post.

    As to the stick — who the hell can seriously consider that?!!! You embrase the worst part of the shuttle as the core of a new craft?? In shuttle flights, the SRBs shoock the wole 1000ish ton shuttle stack so violently crews said it felt like a long runing train wreak. Whats its going to feel like in a “little” CEV and secound stage? Will the vibration be medically dangerous?

    As to personal disgust. For the CEVs budgeted $15 billion you could get a Magnum, shuttle class SSTO, adn a SSTO/TSTO mini taxi if you shop around a little! Of course they would have a major flaw. Their operating costs would be unacceptable low for NASA. YES unacceptably low.

    Which brings me to your #6:

    ==Lastly, I can’t stand the silly argument of trying to maintain jobs from the Space Shuttle program. The whole reason why this program costs so much is because so many people are on the payroll. —

    Sure, it’s politically tempting to try and bribe congresscritters with jobs in their districs, but haven’t we learned how much of an inefficient, bureaucratic mess that is? —

    We have to chose whether we’re trying to open up the solar system for human development, or if we’re trying to run welfare for aerospace nerds. NASA can’t afford both.===

    Space is not NASA’s real job. Pleasing congress criters is. Said persons care a lot about those tens of thousands of jobs, and have screemed bloody murder whenever ideas to lower the head counts at the centers was feilded. After Apollo the one push from congress was to “maintain the space infastructure” — I.E. the head counts at those centers. They don’t much care what they do as long as it sounds plausible to a voter, adn it delivers jobs to districs.

    Going to space is something they would like to do, what they HAVE to do is keep those centers filled.

  2. Jon Goff says:

    Kelly,

    Thanks as always for your comments.

    As to the stick — who the hell can seriously consider that?!!!

    Unfortunately far too many people. Taken on its own, if EELVs and SpaceX and the rest of the industry didn’t exist, it might make a little bit of sense, kinda, sorta, maybe.

    You embrace the worst part of the shuttle as the core of a new craft?? In shuttle flights, the SRBs shoock the wole 1000ish ton shuttle stack so violently crews said it felt like a long runing train wreak. Whats its going to feel like in a “little” CEV and secound stage? Will the vibration be medically dangerous?

    Dunno, maybe those guys at the Astronaut Office wanted a more wicked ride. ๐Ÿ™‚ “You thought the shuttle was wild, wait till you ride this bad boy!” I wish they weren’t getting their jollies at our expense though.

    As to personal disgust. For the CEVs budgeted $15 billion you could get a Magnum, shuttle class SSTO, adn a SSTO/TSTO mini taxi if you shop around a little!

    Well, I don’t doubt that private groups could build and operate several different TSTO designs, and maybe even an SSTO for the $15B NASA wants to spend on developing CEV. The problem is that if you get NASA money, you have to meet NASA bureaucracy demands. I’m willing to bet that XCOR’s composite LOX tank work would probably cost them half or a third as much if they weren’t having to jump through all the silly hoops NASA wants them to (and they were able to talk NASA out of the worst of them!).

    Which brings me to your #6:

    Note: after rereading my quote, I decided to reword that section a little bit to make it more clear and better phrased.

    Space is not NASA’s real job. Pleasing congress criters is. Said persons care a lot about those tens of thousands of jobs, and have screamed bloody murder whenever ideas to lower the head counts at the centers were feilded. After Apollo the one push from congress was to “maintain the space infastructure” — I.E. the head counts at those centers. They don’t much care what they do as long as it sounds plausible to a voter, and it delivers jobs to districs.

    Yet another reason why I don’t expect much out of NASA anymore. The realities of the political games just run totally contrary to what you need to run a good and efficient project. So many people get all excited about the power to tap into billions of dollars of public money, but they don’t realize that once you’ve gone through all the strings attached to that money, there really isn’t much useful that can get done with it.

    Going to space is something they would like to do, what they HAVE to do is keep those centers filled.

    Yeah. Congress critters complain whenever NASA tries to do something useful, calling it waste, but then they turn around and demand that NASA not fire people in their district, even if they’re not doing anything more than sitting around twiddling their thumbs.

  3. Dan Schrimpsher says:

    Yeah. Congress critters complain whenever NASA tries to do something useful, calling it waste, but then they turn around and demand that NASA not fire people in their district, even if they’re not doing anything more than sitting around twiddling their thumbs.

    Technically, the guys who demand NASA not fire people in their district are very excited about NASA doing stuff (as long as it is stuff their district can work on). The Alabama “congress critters” are very much in favor on the VSE, just as long as we build the CEV rocket in Huntsville.

  4. Kelly Starks says:

    > Jonathan Goff said…
    >
    > Kelly,
    >
    > Thanks as always for your comments.

    Glad to have a interesting place to post.

    ๐Ÿ˜‰

    >> As to the stick — who the hell can seriously consider that?!!!
    >
    > Unfortunately far too many people.

    ๐Ÿ˜‰

    > Taken on its own, if EELVs and SpaceX and the rest of the industry
    > didn’t exist, it might make a little bit of sense, kinda, sorta, maybe.

    ;/

    >== maybe those guys at the Astronaut Office wanted a more wicked
    > ride. ๐Ÿ™‚ “You thought the shuttle was wild, wait till you ride this
    > bad boy!” ==

    Oh hell no!!

    ๐Ÿ˜‰

    >==I wish they weren’t getting their jollies at our expense though.

    I wish they were doing something useful.. X-plans, new launchers. Like that shuttle โ€œrefitโ€ idea I talked about to make it into a biamees… Something! I mean I know they got to burn through the budget and keep the head count up – but you could at least waste the money on something interesting!

    ๐Ÿ˜‰

    >== I don’t doubt that private groups could build and operate several
    > different TSTO designs, and maybe even an SSTO for the $15B NASA
    > wants to spend on developing CEV. ==

    McDacs $3 billion budget to field a tested production line of DC-X shuttles.

    >== The problem is that if you get NASA money, you have to meet
    > NASA bureaucracy demands.

    Rule of thumb at McDac was a mil program cost 3 times as much as the same program done commercially. NASA 4 times as much as commercials.

    >== Yet another reason why I don’t expect much out of NASA anymore.
    > The realities of the political games just run totally contrary to what
    > you need to run a good and efficient project. ===

    Yeah when I was there they were always pushing us contractors to increase the team sizes – which lowered productivity.

    To innovate you need tight small tiger teams. Huge distributed armies canโ€™t innovate.

    >> Going to space is something they would like to do, what they
    >> HAVE to do is keep those centers filled.

    > Yeah. Congress critters complain whenever NASA tries to do
    > something useful, calling it waste, but then they turn around and
    > demand that NASA not fire people in their district, even if they’re
    > not doing anything more than sitting around twiddling their thumbs.

    Like the $100 dollar screwdrivers, hammers, etc — that were actually $1 dollar tools with $99 of paperwork to eliminate waste.

    ::AAAAAAAAHHHHHHHHHHH!!!!!!!!!!!!!!!::

    Sorry, had to do that.

    One congressional committee person told a NASA person that โ€œwe donโ€™t care what you do at the centers as long as it keeps that many folks employed.

    I also long held hope NASA would change – spent 15 years working there waiting. Its not going to happen. They arenโ€™t that kind of place.

    The worst thing is they have such great public clout, for decades the public assumed that if NASA wasnโ€™t doing it, then it was impossible – so space was a dead end. NASA in the end convinced the public space was impossible.

    ๐Ÿ™

    Not what I wanted to spend my career doing.

    > Dan Schrimpsher said…
    >
    >==The Alabama “congress critters” are very much in favor on
    > the VSE, just as long as we build the CEV rocket in Huntsville. —

    But Huntsville has no ability to do something like the CEV. NASA has no design abilities like that.

  5. Phil Fraering says:

    Hey Jon…

    Remember all those conversations from way back when about how RLV’s were a waste of time?

    How do you feel about them now that you’re seeing how the modern NASA develops an ELV?

  6. Jon Goff says:

    Phil,

    Remember all those conversations from way back when about how RLV’s were a waste of time? How do you feel about them now that you’re seeing how the modern NASA develops an ELV?

    Well, to be honest I’ve changed my tune quite a bit on that topic, to the point that I’m now a principle in an RLV company (albeit one that is starting with suborbital RLVs). I still think that ELVs can be done far cheaper, and far more reliably, than they are currently done. And I think that using NASA’s experience with developing anything as an argument against it is silly. They’ve botched both RLV and ELV developments. They’re quite talented at botching things. Rather equal opportunity. ๐Ÿ™‚

    That said, what finally got me looking more seriously at RLVs was the testing question. I wanted to have any vehicle I design go through a rigorous incremental testing regime. If it’s possible, such a regime is one of the best ways to find and squash development bugs. I realized that in order to do that incremental testing right, you’d need some way of at least recovering the stage for inspection (to figure out if anything went wrong that you didn’t catch, or to try and figure out what went wrong if there was an obvious failure).

    Once I got thinking about recovery methods, especially ones that I could do in Utah (where I was at at the time), I started down the slippery slope that led me to where I am now–as an engineer and principle at a company making VTVL (DC-X style) reusable vehicles. The development process we’re looking at meshes very well with the way I’ve always wanted to do it, I’m now more confident that we can resolve the key issues that I used to be concerned about, and have generally talked myself into believing in the potential of reusable vehicles.

    I still think expendables have some purpose, and could potentially give RLVs a run for their money in the near to medium term, but for what I’m most interested in, RLVs are just what makes sense.

    Anyhow, you can’t expect me to dogmatically stand beside ill-founded opinions I made when I was only an arrogant 17-year old undergraduate engineer, now would you? ๐Ÿ™‚

  7. Kelly Starks says:

    Once I got thinking about recovery methods, especially ones that I could do in Utah (where I was at at the time), I started down the slippery slope that led me to where I am now–as an engineer and principle at a company making VTVL (DC-X style) reusable vehicles.

    Ironic. I was with McDac during the DC-X program and very enthusiastic, but years of questions about its recovery safty have made me look hard back at HTOL launchers. (Even a couple tricks to get take-off speeds for a near to SSRO down to conventional.) Its not as efficent, but thats not the big problem. It is a relyable design and we have a good experence base with aircraft that assend and desend like aircraft. Even with ones that can take off at well below the speed where their wings can lift them.

  8. Jon Goff says:

    Kelly,

    Ironic. I was with McDac during the DC-X program and very enthusiastic, but years of questions about its recovery safty have made me look hard back at HTOL launchers. (Even a couple tricks to get take-off speeds for a near to SSRO down to conventional.) Its not as efficent, but thats not the big problem. It is a reliable design and we have a good experence base with aircraft that ascend and descend like aircraft. Even with ones that can take off at well below the speed where their wings can lift them.

    The more I look into the issues around VTVL (and I do so quite a bit for my day job), the more I think it’s a solveable problem. The real key with any reusable vehicle is that you really have to design it different from an expendable vehicle. Ie you really have to make sure it is stone-cold reliable, be willing to do lots of flight testing, and lots of iterations. Designing a safe and survivable flight systems is an art, one that is still in its infancy.

    Anyhow, by the time we ever get around to making manned VTVL systems (if we do), we should have hundreds of unmanned flights under our belts, and have a good idea of what we’re doing. Anyhow that’s a discussion for another day.

  9. Kelly Starks says:

    Agree abut the big issue being designing for relyability. Rocket folks have gotten used to taking major short cuts to save costs, and cut margins to increase performance. Ok for throw a way missles, but not for launching major cargo or people used to survival rates much better then a WW-II B17 crew.

    As to VTVL, I was just noting even with jump jets and Helos its accident rate is far higher then HTOL aircraft. Doing it with rockets or chuts is not likely to be even as safe. So I’m drifting back to thinking we should eat the mass and add wings and lifting surfaces. At least it lowers the thermal loads a lot.

    Oh, do you guys do any work with, or know anything about UHTC-C? Ceramic composits with operating temps up to 4300 F have obvious TPS advantages, but I heard some have fiber seperation issues. Just wondering if you heard anything?

  10. Jon Goff says:

    Kelly,

    As to VTVL, I was just noting even with jump jets and Helos its accident rate is far higher then HTOL aircraft.

    This may be an analogy that doesn’t apply very well with respect to rocket vehicles. VTOL aircraft typically have very complicated flow dynamics around them. They are typically not axisymmetric, they often have weird ground effect issues etc. A nice axisymmetric VTVL rocket vehicle may very well (I’m not sure yet) have simpler and safer dynamics than a HTHL vehicle.

    As for the engines being flight critical during landing, there are several dead zones even for modern aircraft where complete engine failure results in a lot of dead people. Engine reliability can be improved, and failure modes can often be made more graceful.

    Doing it with rockets or chutes is not likely to be even as safe.

    I’d say yes for chutes, and maybe for near-term rockets. I think that in the long run we can probably get VTVL rocket reliability better than VTOL or helicopter reliability. It’ll just take work, and lots of flight testing.

    So I’m drifting back to thinking we should eat the mass and add wings and lifting surfaces.

    Well, it’s not just the extra mass. You also have the increased complexity of the whole system once you go to a winged system since you almost definitely need two stages to reach orbit with a winged vehicle. Not impossible, but very difficult.

    Much scarier dynamics IMO. There are those who I respect quite a bit who may disagree (XCOR guys being one). But once again, as I said, if I wasn’t convinced that VTVL can be safely done, I wouldn’t be a principle in a VTVL rocket company. ๐Ÿ™‚

    At least it lowers the thermal loads a lot.

    Not exactly. Total thermal loads go up, but the peak heat transfer rates go down. This means that ablative systems are out, and you need something like ceramics, refractories, or transpiration cooling (my personal favorite at the moment for reusable orbital systems).

    Oh, do you guys do any work with, or know anything about UHTC-C? Ceramic composits with operating temps up to 4300 F have obvious TPS advantages, but I heard some have fiber seperation issues. Just wondering if you heard anything?

    Nope, haven’t been looking at ceramics much. Our suborbital vehicle doesn’t get very hot on reentry. Some sort of heat-sink or high temperature skin on the base should be fine. We have some ideas, but aren’t that far into the development process.

    For orbital vehicles, ceramics, even CMCs seem too fragile for our taste. I’m leaning towards transpiration cooling, while the others are leaning towards finding out what actually works first before making a decision. ๐Ÿ™‚

  11. Kelly Starks says:

    As to VTVL==
    >> Doing it [landing] with rockets or chutes is not likely to be even as safe.

    > I’d say yes for chutes, and maybe for near-term rockets. I think that
    > in the long run we can probably get VTVL rocket reliability better
    > than VTOL or helicopter reliability. It’ll just take work, and lots
    > of flight testing.

    Not sure desending on a rocket blast, or use of a hcute can be as relyable as wings. They certainly arnโ€™t now, but perhaps they can be develop

    >> So I’m drifting back to thinking we should eat the mass and add
    >> wings and lifting surfaces.

    > Well, it’s not just the extra mass. You also have the increased
    > complexity of the whole system once you go to a winged system
    > since you almost definitely need two stages to reach orbit with
    > a winged vehicle. Not impossible, but very difficult.

    Iโ€™m actually working on a paper on that. It looks like it might actually make it a bit easier. A shallow angle winged assent needs much less thrust. Now you need it longer, so with rockets its a wash, but with some of the newer ramjets (very high T/W ratio) you actually could come out ahead dry weigh wise because of the rocket reaction mass tank savings due to the higher ISP. And you get a craft that can fly under power after reentry. (Great for cross range. ๐Ÿ˜‰ )

    > Much scarier dynamics IMO. ==
    ??
    How?

    >== There are those who I respect quite a bit who may disagree
    > (XCOR guys being one). ==

    Good guess. ๐Ÿ˜‰

    >==But once again, as I said, if I wasn’t convinced that VTVL can be
    > safely done, I wouldn’t be a principle in a VTVL rocket company. ๐Ÿ™‚

    I respect your commitment.

    ๐Ÿ˜‰

    Good luck.

    >> At least it lowers the thermal loads a lot.

    > Not exactly. Total thermal loads go up, but the peak heat transfer
    > rates go down.==

    ??

    With the bigger surface area of a winged craft coming in belly first? Iโ€™ld think the kinetic energy distributed over a bigger area would have to lower energy/temperature?

    >== This means that ablative systems are out, and you need
    > something like ceramics, refractories, or transpiration
    > cooling (my personal favorite at the moment for reusable
    > orbital systems).

    How do you get the transpiration system to evenly cool? Hows the mass for the system?

    You might want to check out:

    http://www.ultramet.com/therm.htm

    Their laminate reusable heat shield took 4000F on the hot side, and droped it to under 550F on the cool side (2/3rd of a inch thick. 1.5 lb per ft^2) in a bunch of simulated reentries in a project with Ames. Not sure how brittle it is.

    Just in case your curious.

    >> Oh, do you guys do any work with, or know anything about UHTC-C?
    >> Ceramic composits with operating temps up to 4300 F have
    >> obvious TPS advantages, but I heard some have fiber seperation
    >> issues. Just wondering if you heard anything?
    >
    > Nope, haven’t been looking at ceramics much. Our suborbital vehicle
    > doesn’t get very hot on reentry. Some sort of heat-sink or high
    > temperature skin on the base should be fine. We have some ideas,
    > but aren’t that far into the development process.

    Well good luck. Just wondering about how far along they came.

    >> For orbital vehicles, ceramics, even CMCs seem too fragile for
    > our taste. I’m leaning towards transpiration cooling, while the
    > others are leaning towards finding out what actually works first
    > before making a decision. ๐Ÿ™‚

    Oh yeah, wait for someone else to work out the bugs.

    ๐Ÿ˜‰

  12. Jon Goff says:

    Kelly,

    Not sure descending on a rocket blast, or use of a chute can be as reliable as wings. They certainly arnโ€™t now, but perhaps they can be develop

    You can’t just look at the descent. You have to look at the safety over the whole profile. Sure, for low-performance vehicles wings do make some things easier and safer, but once you start looking into vehicles with a high enough propellant fraction for suborbital or orbital work, and the situation changes quite a bit.

    As it is, we really don’t have much flight experience with either VTVL or HTHL rocket vehicles. You need to be really careful with this things as your intuition based on subsonic, low-propellant fraction vehicles can misguide you when it comes to rocket vehicles.

    Honestly, I think that a good company can probably make either work with far better safety than what is currently accepted. It’ll probably be a while before we’re up to passenger jet levels of safety, but I think we can get there eventually.


    Iโ€™m actually working on a paper on that. It looks like it might actually make it a bit easier. A shallow angle winged assent needs much less thrust.

    But you have to spend more time in the atmosphere, and you have to design a vehicle that can handle well at both subsonic and hypersonic speeds. Doing that with a winged vehicle while still handling all the CG issues right, abort issues, etc is difficult (not impossible, but a definite minus).

    Now you need it longer, so with rockets its a wash, but with some of the newer ramjets (very high T/W ratio) you actually could come out ahead dry weigh wise because of the rocket reaction mass tank savings due to the higher ISP. And you get a craft that can fly under power after reentry. (Great for cross range. ๐Ÿ˜‰

    The devil’s in the details. A lot of people whose opinions I rather respect think that using ramjets and scramjets for acceleration based missions (like getting to orbit) is almost always a losing proposition compared to going with just pure rocket engine. Sure the T/W ratio of those ramjets is probably better than older ones, but how well does it actually compare with a rocket engine? How much time to you really want to spend in the atmosphere? How fast do you really want to be going in the atmosphere? When you look at all the restrictions you need to actually get that ramjet bit to do anything noticable for you other than take up weight, you usually find it isn’t worth it. I’d love to be proven wrong on that, but haven’t seen anything that comes even close yet.

    How?

    The dynamics of a TSTO HTHL are going to be a bit complex, since you have a much more complex flowfield around the system. Particularly if your first stage is trying to be a hypersonic airplane.

    With the bigger surface area of a winged craft coming in belly first?

    I was assuming that we were comparing two vehicles of equal frontal area to mass ratio. You can make capsules or VTVL vehicles with a pretty wide cross section. Especially if you go with deployable drag devices.

    Iโ€™d think the kinetic energy distributed over a bigger area would have to lower energy/temperature?

    Yeah, but it lasts longer, and near the leading edges the flow is much closer to the surface, so more heat gets transfered. Blunt body dynamics really makes reentry thermal systems much easier.

    How do you get the transpiration system to evenly cool? Hows the mass for the system?

    Transpiration cooling systems often have pretty darned good mass numbers compared to others. Most importantly, they’re theoretically more robust, and they’re testable. You don’t need to have cooling be perfectly even, in fact you may want more cooling in some areas than others. The amount of water flow needed is usually so low that you can actually afford to splurge a little. Margin–it’s your friend.

    You might want to check out:

    http://www.ultramet.com/therm.htm

    Their laminate reusable heat shield took 4000F on the hot side, and droped it to under 550F on the cool side (2/3rd of a inch thick. 1.5 lb per ft^2) in a bunch of simulated reentries in a project with Ames. Not sure how brittle it is.

    I’d be surprised if it wasn’t very brittle. With ceramic systems like that you also have to deal with insulation and heat soak issues.

    It may be doable, but I’d want to try it first. You know, maybe put together some small reentry demonstrators, and actually take some data–see how they stack up against each other.

    Oh yeah, wait for someone else to work out the bugs.

    Well, not neccessarily. It’d be great if someone else would, but I figure we’ll probably end up taking our own data.

    Once again, that’s only if we ever get to doing anything orbital. Our focus for now and for the forseeable future is pretty much on suborbital markets.

  13. Kelly Starks says:

    Kelly,

    >> Not sure descending on a rocket blast, or use of a chute can be
    >> as reliable as wings. They certainly arenโ€™t now, but perhaps they
    >> can be develop

    > You can’t just look at the descent. You have to look at the safety
    > over the whole profile.

    Kind of like a chain – you only as safe as you least safe part.

    ๐Ÿ˜‰

    > Sure, for low-performance vehicles wings do make some things
    > easier and safer, but once you start looking into vehicles with
    > a high enough propellant fraction for suborbital or orbital work,
    > and the situation changes quite a bit.

    Not clear what you mean? Obviously I was assuming winged systems with enough propellent to be capable of getting to orbit in 1 or 2 stages.

    >>==
    > Honestly, I think that a good company can probably make either
    > work with far better safety than what is currently accepted. It’ll
    > probably be a while before we’re up to passenger jet levels of safety,
    > but I think we can get there eventually.

    Should be. Course given right now youโ€™d be only slightly more at risk flying a B-17 into Berlin without fighter escort in WW-II, and hundreds of times safer flying combat aircraft into combat zones now — it should be really easy to make safety improvements – given we has such a low base to start from.
    ;/

    >> Iโ€™m actually working on a paper on that. It looks like it might
    >> actually make it a bit easier. A shallow angle winged assent
    >> needs much less thrust.

    > But you have to spend more time in the atmosphere, and you have
    > to design a vehicle that can handle well at both subsonic and hypersonic
    > speeds. ==

    No just sub and supersonic. Not flying any more then mach 3 in the air – which is only about half a mach over top fighters of the 70โ€™s. Which gives you someone to copy.

    ๐Ÿ˜‰

    And not doing scramjet lightens the configuration.

    Time in air adds drag, but ramjets FAR higher ISP compensates.

    T/W for the best ramjet/scramjet/rocket configs have a thrust to weight of over 22 with hydrogen. Drop the scramjet part and integrate it in with a linear aerospike and you might get a effective 40+ to 1, possibly double that with kerosine. No hard data past Areojet’s better then 22 to 1 strut jet ram/scram/rocket rig. You speculation may vary. I assumed about 50 to 1 and got a overall dry mass savings over rocket only shallow or vertical assent. Including calculated losses for the HTOL take off.

    Lox/hydrogen rockets usually donโ€™t have t/w much better then 50/1, Lox/Kerosine 100/1 or a little better.

    >The devil’s in the details.

    And theirs so damn little hard data (I.e. Flight experience) to hang it on. So I do take my numbers with a few grains of salt — and really donโ€™t know how to nail it down.

    >== Sure the T/W ratio of those ramjets is probably better than
    > older ones, but how well does it actually compare with a rocket engine?

    Well the point is how much weight in rocket fuel and Lox tank does it save you.

    Agree though that you REALLY donโ€™t want to go hypersonic (well not seriously) before you get your ship out of the air or you buy a lot more trouble then you save.

    ===
    >> How?

    > The dynamics of a TSTO HTHL are going to be a bit complex, since
    > you have a much more complex flowfield around the system.
    > Particularly if your first stage is trying to be a hypersonic airplane.

    Hypersonic is bad. Agreed.

    ๐Ÿ˜‰

    >> With the bigger surface area of a winged craft coming in belly first?

    > I was assuming that we were comparing two vehicles of equal frontal
    > area to mass ratio. ==

    Oh, I was assuming winged RLVs give a minimal frontal area going up, max coming down – especially with wings and fins, which give more surface to frontal with.

    > You can make capsules or VTVL vehicles with a pretty wide
    > cross section. Especially if you go with deployable drag devices.

    Ballutes are your friend!

    ๐Ÿ˜‰

    >>Iโ€™d think the kinetic energy distributed over a bigger area would
    >>have to lower energy/temperature?

    > Yeah, but it lasts longer, and near the leading edges the flow is
    > much closer to the surface, so more heat gets transferred. ==

    Ah, point.

    >> How do you get the transpiration system to evenly cool? How’s
    >> the mass for the system?

    > Transpiration cooling systems often have pretty darned good
    > mass numbers compared to others. Most importantly, they’re
    > theoretically more robust, and they’re testable. You don’t need
    > to have cooling be perfectly even, in fact you may want more
    > cooling in some areas than others. The amount of water flow
    > needed is usually so low that you can actually afford to splurge
    > a little. Margin–it’s your friend.

    I get nervous with systems that could clog up. Hey car radiators aren’t reliable enough for me. ๐Ÿ˜‰

    >> You might want to check out:
    >>
    >> http://www.ultramet.com/therm.htm
    >>
    >> Their laminate reusable heat shield took 4000F on the hot side,
    >> and dropped it to under 550F on the cool side (2/3rd of a inch thick.
    >> 1.5 lb per ft^2) in a bunch of simulated reentries in a project
    >> with Ames. Not sure how brittle it is.

    > I’d be surprised if it wasn’t very brittle. ==

    Yeah Iโ€™d epoxy a couple sheets of Kevlar to hold broken bits together for a while — though at least reentry shouldnโ€™t shatter anything.

    As to the brittleness, with all the vapor deposited platinum group metals on and in the open celled carbon foam and carbon-carbon outer layer — Iโ€™m not even going to guess what the stuff has for structural properties.

    Agree with wanting to see some test data – preferably flight test data!!

    >==
    > Once again, that’s only if we ever get to doing anything orbital.
    > Our focus for now and for the foreseeable future is pretty much
    > on suborbital markets.

    Well in 3-4 years there should be a couple of the Alt.space RLV programs doing orbital, so somefolks will be using tests.

  14. Mr. X says:

    “The Stick” should definitely be thrown to the dogs.

    My biggest concern is safety. Challenger should have taught us about the inherent danger in flying segmented SRB’s. Even monolithic SRB’s aren’t impervious. Once you start the beast, there’s no stopping it.

    There’s also the issue of the thrust profile for “The Stick.” Most solids tend to produce lots of thrust. The grain will definitely need to be changed for a manned launcher.

    The SSME idea is ridiculous. It’s too complex and too expensive to be mass produced and expended. I like the J-2, and it was a good engine in its day, but the RS-68 might be a better choice if the J-2 can’t be built again. Still, Rocketdyne has plenty of J-2’s in storage, so I don’t think it would be that hard to restart production.

    I like Big Gemini and it would probably be the perfect CEV design if it was modified to have a docking collar in the nose. However, NASA is now demanding reusability from the CEV. Lockheed has proposed a 70-ton lifting body monstrosity. It’s unknown what Boeing will propose. The ideal shape for this reusable capsule would be a bi-conic, like the Russian Kliper.

    How should we get to the moon? Launch a Kliper and a LEM on Atlas V’s, then launch the trans-lunar injection stages on Atlas V Heavies and Delta IV Heavies. Dock them all in Earth orbit and send them off.

  15. Kelly Starks says:

    > MJ said…
    >
    > “The Stick” should definitely be thrown to the dogs.
    >
    > My biggest concern is safety. Challenger should have taught us
    > about the inherent danger in flying … SRB’s. —

    Agree!! The mear vibration level of a light object on a SRB is insane. Even with the shuttle stack the astrounauts all took a real sign of releif when the SRBs seperated.

    > The SSME idea is ridiculous. It’s too complex and too expensive
    > to be mass produced and expended. —

    You could with good manufacturing set ups. Course realisticly they launch so seldom, the cost and production issues aren’t any real impact. I mean the SSMEs can’t cost much more then a couple million each – the tank is $50 million and its going into the ocean. That would buy a lot of SSMEs.

    > How should we get to the moon? Launch a Kliper and a LEM on Atlas
    > V’s, then launch the trans-lunar injection stages on Atlas V Heavies
    > and Delta IV Heavies.—

    Kliper is Russian. We can’t use it, adn NASA wouldn’t regardless. It would be political suicide!

  16. Mr. X says:

    Kelly,

    You might be able to achieve lower costs with “good manufacturing setups” on the shuttle main engine, but it doesn’t change the fact that the SSME is mechanically complex. It has tiny channels to allow coolant through the skin of the nozzle.

    Engines like the RS-68 were designed to be thrown away. They have a greatly reduced parts count. Instead of going with tiny cooling channels, they simply use an ablative liner in the nozzle.

  17. Kelly Starks says:

    >>MJ
    >>
    >> You might be able to achieve lower costs with “good manufacturing
    >> setups” on the shuttle main engine, but it doesn’t change the
    >> fact that the SSME is mechanically complex. It has tiny channels
    >> to allow coolant through the skin of the nozzle. —

    Oh I agree the SSME is a bad design. I mearly said you could mass produce it cheaper, not that it was a economically desirable idea. Though for NASA it could be politically advantagious to build in shuttle systems regardless of their utility.

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