A Path Not Taken

I have to admit that last post was kind of weak. Most of the good points had already been made, and I’m not sure I actually added anything relevant to the discussion. So, as penance, and since the antibiotics I just took say not to lie down for 30 minutes after taking them, I’m going to try and actually put out some original thought on a topic that I’ve been thinking about for a while.

Monte Davis got me thinking about things again, and lessons from the Shuttle program. One of his big points (if I’m not mangling it unduly) was that the problem with Shuttle wasn’t just that it mixed expendable parts with reusable parts. He pointed out that the fully reusable TSTO designs that had been studied were so challenging that they might have been just as big of a mess (or even worse if that’s imaginable!). The problem was that the Shuttle was just a bridge too far. NASA bit off far more than it was ready to chew. The requirements were too high. They were suffering from the conceit that they could somehow jump straight to a large, high-flight rate reusable space transportation right from the very first generation.

I full-heartedly agree that there’s no way NASA could have developed the monster sized TSTO fully-RLV designs that were dropped in favor of the current Frankensteinian amalgam of expendable and “refurbishable” rocket hardware. What I wonder is if there was a different path that could’ve been taken. One that would’ve allowed for more incremental development. One that would’ve allowed for a truly reusable launch vehicle (albeit of much more modest capabilities). One that wouldn’t have become the mess we have in today’s Shuttle.

I’m not conceited enough to state that I know the following would definitely have been better. But I wanted to toss the idea out for discussion. See what you all think.

One of the big not commonly discussed problems with the Shuttle was that NASA was trying to keep as much of the Saturn team together as possible. They were shutting down both Saturn lines, and wanted to keep as many of the engineers and technicians as they possibly could in a time of tight budgets. Keeping as many Saturn engineers around as possible required a big budget development project. However, money was a lot tighter in the post-Apollo days. In order to get the money for Shuttle, as I understand it, they had to scrap both Saturns, and go snuggling up with the Air Force. They had to make their Shuttle design be everything to everybody. Keeping as many of the Saturn engineers as possible involved in the development of the Shuttle implied very large development costs. Those costs were high enough that they had to get the Air Force on board as well in order to get the funding they needed. In order to do that, they had to bloat the requirements even worse than the original Shuttle concepts. However, the requirements grew quicker than the additional money, and in the end they ended up having to make all sorts of compromises.

What if they had intentionally bitten off a smaller task at first. What if they had retired the Saturn V, and slimmed down the staff for the Saturn IB (or better yet, auctioned it off or allowed the companies involved to commercialize it), and then done a much smaller first generation “shuttle”? This shuttle might have only been capable of putting a couple thousand pounds into orbit, and might not have gone straight to an operation vehicle. This wouldn’t have been a program trying to keep as much of the Saturn team together as possible, or an attempt to replace all existing rockets in one fell-swoop. It would’ve been an X-vehicle in reality.

About a month ago, on NASASpaceFlight.com’s L2 section, there was discussion of some conceptual design work done by Dan DeLong (of XCOR) back in the mid 80s that might have been a good way of doing things. The concepts (“Space Plane” and “Frequent Flyer”) that he developed while working for Teledyne Brown were air-launched HTHL style RLVs. They used a modified 747 carrier plane as the first stage, and a LOX/LH2 powered reusable upper stage. While the bigger “Space Plane” design baselined an SSME and 6 RL-10s for the orbiter, and would’ve been barely launchable on a heavily modified 747, I realized that by dropping the cargo capacity a bit, you could both eliminate the SSME and probably cut the modifications on the 747 substantially.

It’s just an idea, and LOX/LH2 isn’t necessarily the right propellant combination for things, but imagine if a vehicle like that had been built. It wouldn’t have required any new propulsion development, since RL-10s were on-the-shelf technology by then. The system would’ve been a lot more reusable, simple, and safe. The engines were a lot easier to maintain and reuse than the SSME. Since the stage had the tanks inside, it would’ve had a much “fluffier” reentry, which when combined with the lower cross-range design, would’ve allowed for a much more robust TPS system to be used–no need for ceramic tiles. Doing an extensive flight test involving dozens of test flights would’ve been perfectly reasonable. You probably wouldn’t have even needed much better of an escape system than a standard aircraft ejector seat, since most of the failure modes would’ve been a lot more benign than for most typical rockets.

Let’s be honest though, the performance would’ve sucked rocks. You would likely have been lucky to get 3000lbs of useful cargo out of the vehicle (in the unmanned version), or possibly 2-4 people on board. This wouldn’t have been everything for everybody. But it would’ve been an extraordinarily good starting point for learning how to design and operate reusable vehicles.

Anyhow, my half-hour is up, but what do you guys think?

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27 Responses to A Path Not Taken

  1. john hare says:

    I think NASA is constantly in the position of people that live beyond their means. I have met thousands of people that live week to week because they purchased more house and vehicle than they really can afford. The result is that they spend everything they can get to maintain what they have and very little investment for the future. If you have ever tried to convince one of these people that they could live a better life with a smaller house and cheaper car, then the problems NASA has come into a bit better focus.

    Just as a smaller house and cheaper car allow a family to save, invest and still have disposable income, the vehicle you described would do the same on a national scale. The problem is the same also, convincing them that living below their means allows them to increase their means in the long term. Except that not spending the entire budget each year means that next years budget gets slashed. I’m at a loss to find that part of the answer.

    I agree on the vehicle idea. A small one then to build experience could have led to a far more capable follow up than anything in the works now.

  2. Josh says:

    You just described the X-15 ‘s unflown path to an orbital vehicle. To bad no one followed it up until 2004 (SS1).

  3. Anonymous says:

    I don’t think an orbital launch vehicle could have been done as an X-vehicle. Even with small payload. It’s just way too big and complicated.

    Rather X-vehicle development should have started with even more modest things. Like technologies for reusable first stages. The make or break here is the engines. Maybe something F-1 derived. Or then something completely new. But less ambitious than SSME, and thus cheaper and more maintainable.

    Perhaps they could have kept Skylab up and fly Saturn Ib:s.
    Do small upgrades to the Apollo capsule (and shrink the propellant tanks).

  4. Anonymous says:

    There are other factors that influenced how we ended up with the shuttle as it exists today. Hubris is not the only one. You have to look at the requirements they were given. For one thing, I recall from reading other articles on this topic that the military was insisting on a huge cargo capacity. They wanted to be able to use this system for all their launches. In hindsight, the requirements were unrealistic, but those charged with designing the vehicle didn’t get to set them.

  5. Jon Goff says:

    Josh,
    There’s still a ways to go, but part of my point with this thought exercise is that an orbital RLV (if you pick an easy approach with modest performance requirements) is something we’ve probably been in a position to do for a while. The challenge now is that since Shuttle and X-33 and other similar programs have made RLVs look so hard and so expensive, now there’s that extra difficulty to deal with above and beyond the engineering. I think that of all the damage NASA has done for the cause of low-cost space access, the bad example of the Shuttle is probably worse than anything else.

    ~Jon

  6. Jon Goff says:

    Anonymous,
    I don’t think an orbital launch vehicle could have been done as an X-vehicle. Even with small payload. It’s just way too big and complicated.

    Maybe, maybe not. The vehicle in question would likely have only had a GLOW of 100klb, with a dry mass in the 10klb range. It isn’t so big that I would rule out being able to do it as an X-Vehicle, or at least as a prototype flight-test vehicle. The big trick is that the big upper stage is a slightly modified existing aircraft, as opposed to a massive, fully rocket powered first stage.

    Rather X-vehicle development should have started with even more modest things.

    I agree with you, I was just trying to minimize the distance between my counterfactual and reality. I do agree though that doing at least 1-3 intermediate X-Vehicles before trying for the first orbital one (even a small orbital one) would likely have been better. But at least a small initial orbital vehicle could’ve been done without a lot of engine development. It wouldn’t have been perfect, but it would’ve been an opportunity to start learning, and to demonstrate the capabilities needed for many potentially huge markets.

    Like technologies for reusable first stages. The make or break here is the engines. Maybe something F-1 derived. Or then something completely new. But less ambitious than SSME, and thus cheaper and more maintainable.

    That’s why I was looking at very small orbital RLVs. It’s just going to be a long time before you’re able to combine the words “F-1 derived” and “cheaper” and “maintainable” in the same sentance without laughing. Avoiding new engine development for a first generation small RLV is big, because it allows you to focus more on the other aspects like operations. Once you have those, you can start iterating on the engine design or approach…

    ~Jon

    Perhaps they could have kept Skylab up and fly Saturn Ib:s.
    Do small upgrades to the Apollo capsule (and shrink the propellant tanks).

  7. Jon Goff says:

    Anonymous,

    There are other factors that influenced how we ended up with the shuttle as it exists today. Hubris is not the only one. You have to look at the requirements they were given. For one thing, I recall from reading other articles on this topic that the military was insisting on a huge cargo capacity. They wanted to be able to use this system for all their launches. In hindsight, the requirements were unrealistic, but those charged with designing the vehicle didn’t get to set them.

    The point I tried to make was that the only reason why military requirements even came into play was because NASA needed military money for their huge Shuttle project. And the reason why the Shuttle project was so huge that it needed AF buy-in was because they were trying to do a development project that could keep as much of the Saturn engineering team together as possible.

    If they had picked a much more modest first goal, they could have reduced costs low enough that they wouldn’t have needed AF buy-in, which means those payload (and crossrange) requirements would’ve never come to the table.

    ~Jon

  8. kert says:

    One comment. Why is everyone thinking so big ? I mean, a useful satellite in LEO can weigh 100kg or less. An orbital RLV to deliver that sat, come back down and deliver the next one would be pretty useful in its own right, not to mention all the advances in mainstream thinking that such an X-craft would bring.
    besides, after that chinese ASAT kaboom the market for such satellites just went even wider.

  9. Jon Goff says:

    Kert,
    Well, there is some merit to even smaller RLVs like you suggest. And it might be necessary to drop back to that size for a first generation RLV. I was only suggesting 2-3klb payload, because that would give enough room for 2-3 people on-board. There really isn’t a huge demand for 100kg LEO satellites, but a 100kg to orbit vehicle might make a great FedEx/UPS first generation RocketMail carrier. Especially if it can operate out of major airports.

    Basically 100kg might be able to do some interesting things, but isn’t likely to have much of an orbital market for itself. Once you have something that can fly 2-3 people though, you have a lot more orbital and terrestrial markets you can grow into.

    We’ll see though. A single engine RL-10 derived airlaunched SSTO could likely do 100kg to orbit, or a bit more to Syndey…so that might be a start.

    Oh, and before anyone burns me at the stake for being a Hydrogen Lovin’ Heretic, RL-10s have been demonstrated with Methane as well….

    ~Jon

  10. Iain McClatchie says:

    It’s just going to be a long time before you’re able to combine the words “F-1 derived” and “cheaper” and “maintainable” in the same sentance without laughing.

    Why is that? The F-1 was definitely reusable. I don’t know how maintainable it was. I think a parachute-recovered single F-1 powered first stage for the Saturn 1B would have been a pretty interesting development direction, especially if followed by a project to either cost-reduce the J-2 (J-2X) or produce an upper stage LOX-Kero engine.

    Like you said, the important thing is to avoid engine development, and keep the flight rate up. But how do you do that when your engines cost so much? Do you think a program to cost-reduce the F-1 across a 10-launch-a-year program would have been significantly cheaper than redesigning the engines from scratch, as we’ve done a couple of times (SSME, RS-68, RD-180 sort of).

  11. kert says:

    There really isn’t a huge demand for 100kg LEO satellites, but a 100kg to orbit vehicle might make a great FedEx/UPS first generation RocketMail carrier. Especially if it can operate out of major airports.
    Just what price point are you keeping in mind when you say there isnt a huge demand ?
    Of course i dont have to tell you that demand depends on the price. Or are you suggesting that this market is perfectly inelastic ?

  12. Chris says:

    I’m not sure there would be a market for a 6hr global freight service. Not when it costs you $100,000 to deliver a 10kg package in 6 hours, vs $200 to have the same package delivered by regular airfreight in 24 hours.

  13. Jon Goff says:

    Kert,
    Just what price point are you keeping in mind when you say there isn’t a huge demand ?
    Of course I don’t have to tell you that demand depends on the price. Or are you suggesting that this market is perfectly inelastic ?

    I think the market will get elastic at some point, but currently those small sats are mostly a novelty item made by universities and such. Just due to the current funding nature of such programs, it’ll take some doing to transition them into a high flight volume market. Even if you were giving them away for free, I think it would take a couple of years to ramp up to more than 100 flights per year of small sats. And I just don’t think you could make money off of that low of a flight rate with that small of a payload.

    Now, sending small packages intercontinentally, really darned fast…that could be more of a market.

    ~Jon

  14. Jon Goff says:

    Chris,
    I’m not sure there would be a market for a 6hr global freight service. Not when it costs you $100,000 to deliver a 10kg package in 6 hours, vs $200 to have the same package delivered by regular airfreight in 24 hours.

    First off, I think your price magnitudes are off quite a bit. If this took off, I could see costs dropping far enough that FedEx or UPS could offer it at $250-500/kg (which would equate out to $2.5-5k for that package). There was enough demand for such services back in the 80s or 90s that one of the major carriers (can’t remember if it was UPS or FedEx) was seriously willing to sign a firm fixed price contract with Lockheed or Boeing (or one of their predecessors) to build such a beast.

    They’re a little gunshy now after being blown off, but not about the market.

    ~Jon

  15. Bill White says:

    $250-500/kg

    How many flights daily? How much payload per flight?

    Every flight crewed? Life support and pilot safety gear (parachutes) will be heavy.

    Robotic flight control (UAVs) would lower the cost per kilogram substantailly.

  16. Jon Goff says:

    Bill,
    Specifics at this point are even worse speculation than my counterfactual. Honestly, who knows. DC-X showed that an RL-10 powered RLV could get to a 1-day turn time after only a handful of flights. I imagine that depending on the details, you could probably fly such a system at least once per day, and possibly twice. More than twice becomes a challenge because of the time required to restack the stage, reload the cargo, and refuel the thing. If demand were high enough in some locations, it might be possible to get up higher than that….but once again, it’s impossible to say anything definite at this point. Who’s to say that an air-launch assisted SSTO like that is even the right approach? I’m not sure myself.

    For the discussion kert was talking about (the 100kg) version, I was assuming unmanned. But for the 2-4klb to orbit version I was talking about, I assumed that many flights would have an on-board pilot (though some would be remotely operated).

    But anyway, these numbers are purely speculative anyhow. And there are real costs for flying unmanned as well. It’s a tradeoff an a not obvious one. If I were flying to service a station, I would probably insist on having either a pilot on board, or a piloted tug. Manned rendezvous and docking are just so much easier and more reliable than trying to automate things.

    ~Jon

  17. Chris says:

    Even if you can do $500 per kilo, no one is going to pay that sort of coin when we already have a 24 hour global package delivery infrastructure to all major regional hubs for a twentieth the cost.

    Now, packing an orbital craft isn’t likely to be as simple as loading a ULD on the next available widebody leaving LAX. Best case, it’s going to take a couple of hours to integrate the payload. After also considering the ground leg to actually deliver the package to your office, you’re already looking at about 12 hours.

    In a world meshed with high bandwidth satellite and fiber communications infrastructure, why would anyone in their right mind pay $5000 to deliver a package in 12 hours, when they can pay $250 to deliver it in 24 hours?

  18. murphydyne says:

    Regarding the suborbital delivery market, I can reasonably see there being a market for certain documents that require signatures, perhaps confidential corporate information that one doesn’t want to send over the net, or small, high value items like prototype chips and boards. I can easily see these accompanying passenger sub-orbital hops, as humans are still the most valuable cargo.

    Don’t discount the desire of high power dealmakers to close an international mega-deal in one day by shipping the documents suborbitally to race the Sun.

  19. Jon Goff says:

    Chris,
    Are you sure that you can get packages delivered within 24 hours between any major metropolitan areas on the globe? The reason why I ask is that there are many such destinations that require flight times of over 20 hours as is.

    All I know is that the people closest to this market seem to think there’s some real demand, even at the elevated prices. I can’t remember if it was UPS or FedEx, but if they’ve got market data solid enough that they were willing to spend over a billion dollars contracting with Boeing or Lockheed to build them a vehicle that could service that market…I tend to take it a bit more seriously.

    Why would it take “a couple of hours to integrate the payload”? Wouldn’t you use some sort of standardized packaging? Sure, it’d be more expensive because it’s designed to handle much higher G-loads, but if you’re spending the money to buy a bunch of these things, don’t you think they’d spend some money to make the loading/unloading as quick and seamless as possible?

    Even if you botched operations so bad that you could only cut the trip time in half, there’s a good chance that there will be demand anyway. And if they actually take the time to make sure the operations are actually well-oiled, they’ll probably be able to do even better.

    ~Jon

  20. Karl Hallowell says:

    My take is that a six hour hop isn’t unreasonable and it probably can be lowered. After all the suborbital part is around two hours or less, right? The rest is opinion, but I think a dedicated business can really cut a lot of time in the other legs of the trip and in package integration.

    But even if it did take 12 hours, there would be a market for it. $5000 is a pretty good price to shave 12 hours off a critical component and save 12 hours of downtime at some remote work location (which in turn might save hundreds of thousands of dollars). Whether there’s enough such business to make that viable is a different story.

  21. tankmodeler says:

    Up until recently (and maybe even to today) there was a small airline running DC-3s and DC-4s out of Toronto moving auto parts to and from various suppliers and OEM plants to make sure the plants don’t wait and the suppliers aren’t on the hook for hundreds of thousands of bucks per hour. The cost per pound isn’t the same, but the relative costs to these companies is.

    There is a market for things that would normally be excruciatingly expensive when the consequences are even worse. Between the largest cities, I’m sure there is enough market to ship packages at $500/kg as there are enough business with even very ocassional need where time is that critical.

    Paul

  22. kert says:

    two words: organ transplants.

  23. Ferris Valyn says:

    While I agree that this is a market to pursue, given the current regulations on the books right now, is there sufficent regulation on the market for this to become a viable industry? With something like Space tourism, the FAA has done some peliminary work on this – has there been any attempt to address the regulatory structure needed to cross international boarders and the like?

  24. Monte Davis says:

    Jon — no mangling at all :-) I’m trying to get spacers to see three things:

    -That CATS really is hard, because we start in such extreme corners of both engineering and economic trade space

    -That an emphasis on clean-sheet, “great leap forward” solutions is not just misguided, but counterproductive. It draws both thinking and investment away from the modest, incremental steps that could actually, with patience and persistence, get us somewhere.

    -And that the pace-setter for progress is not years (as in “we did Apollo in 8 years, so why aren’t we on Mars?” or “32 years after Kitty Hawk we had the DC-3″) but experience, in flights and operations as well as in design iterations. By that measure, it’s not even 1908 yet.

  25. Jon Goff says:

    Monte,
    Glad to hear from you, especially seeing as how you’re the one who got me started on this line of thought.

    Regarding your three points, I just had a couple of comments:
    That CATS really is hard, because we start in such extreme corners of both engineering and economic trade space

    Coming more from the engineering side, the economic half of the problem seems far more challenging. Most of the engineering steps that need to be taken are just that–simple steps. There’s a whole lot of them, but no given step is particularly challenging *unless* you try skipping intermediate steps.

    It’s the economic side that’s more scary, because as I see it, while there do appears to be islands of profitability along the way, it isn’t clear that they are in every one of the places you’d want one to be. What I mean is that it appears that there are economic chicken-and-egg issues with areas like propellant depots as well as the more commonly noticed one for reusable launch.

    It’ll be an interesting and challenging nut to crack.

    That an emphasis on clean-sheet, “great leap forward” solutions is not just misguided, but counterproductive. It draws both thinking and investment away from the modest, incremental steps that could actually, with patience and persistence, get us somewhere.

    I think a note of caution is merited with this suggestion. Incremental improvements of existing expendable vehicles are very unlikely to result in significant improvements in safety, cost, or dependability, even over a long period of time. To paraphrase CS Lewis, when you’ve gotten off on the wrong track, sometimes the quickest way to make progress is to turn around, retrace your steps, and then get back to the right track. In other words, I think that we have to get onto the right track first before incremental improvements over time will yield dramatic results. I’m biased of course, but I think that several of this batch of entrepreneurial space companies are finally getting that.

    Reusability is good, but don’t try to jump straight from where we are to a fully-reusable spaceplane. Start small and suborbital, get experience, learn what works, and incrementally work your way up from there. Grow markets as you go, use the less-capable vehicles as testbeds for technologies for the latter vehicles. Etc. But I’m probably preaching to the choir there.

    And that the pace-setter for progress is not years (as in “we did Apollo in 8 years, so why aren’t we on Mars?” or “32 years after Kitty Hawk we had the DC-3″) but experience, in flights and operations as well as in design iterations. By that measure, it’s not even 1908 yet.

    Yeah, we did manage to get ourselves sucked into a premature plateau of expensive huge launchers from which we’ve never fully recovered. It’s instructive to realize that the Centaur guys (who probably have more flight experience with upper stages than any other group in the Western world) only have ~180 flights under their belt, on only a small handful of designs. A decent flight test program for a series of suborbital vehicles that eventually leads to orbital vehicles will likely net more actual flight experience on more vehicle iterations than even they have.

    ~Jon

  26. Jon Goff says:

    Ferris,
    You have a legitimate point. While the current FAA regs lay a lot of the groundwork for intercontinental suborbital travel, there are still some regulatory uncertainties that will have to be retired along the way. Probably once one or more suborbital ventures really starts showing some solid technical progress, it will be possible to start reattracting the attention of the UPS’s and FedEx’s of the world. They’ve got the clout and experience to start working on that so long as it looks like the technology will be ready for them by the time they’re done solving the regulatory issues.

    ~Jon

  27. Monte Davis says:

    Coming more from the engineering side, the economic half of the problem seems far more challenging

    Except (evil grin) as your subsequent remarks show that you know, they’re intertwined. In the absence of unlimited Space Fairy funding, your first few engineering steps have to start generating enough ROI to pay for subsequent ones. Spacers dream of one big “knee” in the cost/demand curve — when it’s much more likely you’ll need to find and exploit a series of little ones.

    On point two, I admit I lean to the reusable/suborbital route, but I try to remain agnostic on the religious issue of reusable vs expendable. At least in principle, there are real cost-lowering possibilities in both big dumb boosters and in truly mass-produced ELVs that have never been tried. Both would face their own very high economic hurdles, of course, but it’s arguable they don’t demand as much learning beyond what we know now as the increments-to-orbit reusable route.

    Point three comes close to the ultimate, painful statement of the chicken-and-egg situation: the only sure way to make it cheaper is to do a lot of it, and it’s hard to do a lot of it while it’s so expensive. :-(

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