It's also untrue, US rocketry kept varied propulsion types throughout its history including both RP1-only and LH2-only as well as mixed stages, HTPB and Aerozine. Your painting of rocket scientists as some sort of confederacy of dunce unable to get a grip on tradeoffs is not only inane it's insulting bullshit.
Everyone who grew up idolizing rocket scientists should read it. If you have problems with missing pages or broken figures, try a different PDF viewer. The PDF has something odd about it that confuses some in-browser viewers.
My account was simplified, but the tangent was long enough already. It's true that in the early days of US rocketry (through the 1960s), there were a large variety of propulsion types that were experimented and deployed. The stasis didn't really set in until the 1970s.
Since then, it's also true that solids and hypergolics continued to have a role, both as strap-on boosters (because gravity losses) and in military systems (and their derivatives) where cryogenic liquids aren't advisable. (The military was always more whole-systems and pragmatic about their approach to rocketry.) Finally, it's also true that non-LH2 legacy rockets (and their closely-related derivatives) continued to fly (because switching costs).
However: in civilian rocketry (eg. NASA), as far as new developments were concerned, the picture is as I described. I was peripherally involved in that scene during the 1990s and had many people at NASA and LockMart tell me personally, quite explicitly, that specific impulse was very nearly the sole determinant of rocketry, and that therefore no fuel other than LH2 would ever be considered. Feel free to look at the kind of arguments cited during the fuel-density wars on sci.space.policy if you want a feeling for the kind of vehemence with which this opinion was expressed.
So, yes, I stand by my story. From the mid-1970s through the mid-2000s, US rocketry development was wholly paralysed, due in very large part to these kind of attitudes and overly-narrow optimisations. As evidence, I present the NASP, X33, and SLI, amongst dozens of smaller, equally failed initiatives. Feel free to counter with some examples of successful new rockets (as opposed to derivatives like the Pegasus, Taurus, and Delta III) developed during that period. The only examples you'll be able to find are Delta-IV -- which switched to LH2 at frankly mind-blowing expense, has had an uninspiring career, and is about to be axed -- and the Atlas V -- which gave up and just bought LOX/RP1 engines from Russia, since the US had lost the expertise to develop decent LOX/RP1 engines itself.
I'm not saying that the US civilian aerospace industry was a confederacy of dunces, just that for 30+ years it had the productive output of one. It was certainly well-supplied with smart people, but yes they were absolutely unable to get a grip on tradeoffs, and it showed.
> is not only inane it's insulting bullshit.
You've got a lot of HN Karma, but you haven't yet learned that people here prefer evidence-backed arguments to ad-hominem attacks?
At the time, however, I recall hearing endless griping from various corners that NASA had the gall to fund a non-LH2 engine. Internally, this was justified as being nothing more than a cheap and cheerful way to get the X-34 to its flight regime -- definitely not a serious rocket engine, no sir! That was LH2's job! Everyone knew that!
The support of the RP1 rebels within NASA wasn't enough to keep it alive, and the program was cancelled after a few years. Later, it was resurrected as the template for SpaceX's first generation engines. So I personally consider this to be the exception that proves the rule.
Your evidence is:
>I was peripherally involved in that scene during the 1990s and had many people at NASA and LockMart tell me personally, quite explicitly, that specific impulse was very nearly the sole determinant of rocketry... Feel free to look at the kind of arguments cited during the fuel-density wars on sci.space.policy if you want a feeling for the kind of vehemence with which this opinion was expressed.
Your entire point is based on bulletin board discussions and anecdotal evidence from being peripherally involved with rocketry in the 90s (which given context, I'm taking to mean "I hung out in space forums and bulletin boards and talked with people who claimed to be rocket engineers.")
I enjoyed reading both of your posts about this (with a grain of salt), but it's a bit silly to call someone out for lack of evidence after writing several hundred words without a single piece of hard evidence supporting it.
Oh for fuck's sake. I don't like arguments from authority, but if you really want one: yes, I hung out on internet space forums in the 90s and am thus aware of their contents. But I also was a member of the Space Access Society and regular attendee of its conferences; an organiser for the National Space Society and regular attendee of its conferences; and an organiser and founding member of the Mars Society and regular attendee of its conferences. In this context, I was personally well-acquainted with folks like Gary Hudson, Robert Zubrin, and Buzz Aldrin, as well as innumerable lesser-known individuals from NASA, Boeing/Lockmart, and the various alt.space renegades. The stories I tell come directly from my contacts with them.
Furthermore, the "evidence" I provided was citations of the NASP[1], the X-33[2], and the SLI[3]. The first two represented NASA's flagship attempts to develop new space-launch systems during 80s and 90s; they failed due to weight growth and integration problems stemming from over-optimisation of the (LH2) propulsion system at the expense of all the rest of the vehicle's systems. By the time of the SLI in 2000, RP1 was starting to find a (small) place at the table again, but the program still failed due to too narrow a focus on propulsion optimisations. I figured that anybody familiar with the space industry (as the person I was replying to seemed to be) should be familiar with these failures and their underlying causes; they are not exactly secrets.
1: https://en.wikipedia.org/wiki/Rockwell_X-30
I'm absolutely certain that Masklinn did not assert that the optimal design was used every time or that NKoren's comment was completely lacking any accurate information. Neither of these assertions needs to be made to dispute the central idea that US rocket scientists are too incompetent to even consider alternative fuels or broader design tradeoffs.
What do you mean by this? The Mercury Atlas launch vehicle used kerosene / LOX in its first stage. The Saturn V used kerosene / LOX in its first stage and LOX / LH2 in subsequent stages.
Also, for the majority of spaceflight, both manned and unmanned, "US rocket scientists" were the government, right? Especially after WWII.
The STS famously had all sorts of contradictory goals (some came from outside NASA) that resulted in sub-optimal design tradeoffs--which in turn required the highest-performance engines NASA could get their hands on.
From the outside, looking back, it seems like the Space Shuttle was so (unexpectedly) demanding that it basically took over NASA for 25 years. Maybe there just weren't enough resources to pursue other launch vehicle ideas, even if people there recognized the need.
The days up to and including the Apollo missions were the US's glory days; all the great innovation in rocketry was happening then, and it culminated in the Saturn V, which was a big success (esp. considering the level of overall technology back then, and what they were trying to do). And, as you pointed out, it used kerosene. It still remains (I'm pretty sure) the largest and heaviest-lift launch vehicle in all of human history. We still haven't surpassed it, and it was designed in the 1960s.
What have we done since the Apollo program was canceled early? Nothing as notable. A bunch of really expensive launches to LEO with an overpriced space-going pickup truck basically. And a bunch of small launches (satellites, probes, etc.) using rockets that were designed way back then for launching nuclear weapons. We're still highly dependent on rocket engines built by Russia. The whole Space Shuttle idea itself was stupid: the costs and complexity were huge because of the idiotic requirement of being able to retrieve military satellites from orbit and bring them back intact and in secret. If it weren't for that, they never would have come up with such an absurd design, and would have just stuck with much cheaper capsules like the Soyuz and the upcoming manned vehicles by the US.
ISS? Hubble? Various Mars rovers?
Sure they aren't as notable as putting humans on the freaking moon, but that's also a pretty impossibly high bar to match. The only thing that would best it is humans on Mars.
> We're still highly dependent on rocket engines built by Russia.
That's not entirely true. The Soyuz-U does have by far the most launches of any system at 771, true. But the still successful Atlas II (63 launches and also the most reliable system to date) used all Rocketdyne engines. The newer Atlas V does use a Russian engine for the first stage but Rocketdyne for the second.
The Delta IV is also all Rocketdyne. It's also entirely LH2/LOX and yet weighs less than the Falcon 9.
As I said before, nothing as notable.
>Sure they aren't as notable as putting humans on the freaking moon
And it seems you agree with me!!
>but that's also a pretty impossibly high bar to match. The only thing that would best it is humans on Mars.
Wrong, there's plenty of things that would best Apollo. A serious space station (like the rotating one in 2001) perhaps at a Lagrangian point, a Moon base, Moon or asteroid mining operations, orbital construction of a longer-range spacecraft, creation of nuclear spacecraft engines, etc. Basically all the stuff we dreamed about back in the Apollo days and then never bothered to do and just forgot about.
Their robotic missions have been hugely successful.
Consider just the number of them: Viking, Voyager, Galileo, Deep Space, Cassini, New Horizons, Dawn, Kepler, and Juno. That's not even counting our many Mars probes. It's pretty impressive to launch a new interplanetary probe that frequently, and every one of them accomplished its mission.
We have now sent probes to every planet in the Solar System, two dwarf planets, asteroids, and comets. If we are still in an era where crewed interplanetary travel is impractical, we're making the most of it with these uncrewed missions.
Probes are nice for science, but they really don't inspire people the way manned flights, space stations, etc. do. Nor do they require nearly as many resources; they comparatively cheap and simple. The resources poured into Apollo were enormous, and the technologies derived were hugely significant. What technologies were derived from New Horizons? Probably none. I'm not saying it shouldn't have been launched; it was absolutely a worthy project. But it just doesn't compare to Apollo in any way. So as I said before: "nothing as notable".
No, it's because their system is much less capable and benefits from having a starting point of 50 years of accumulated knowledge.
Take Musk & the Space-X team and plop them in 1980 and you would not get the same Falcon 9 that exists today. You wouldn't get anything close.
Comparing the space shuttle to the Falcon is idiotic, anyway. The shuttle had capabilities that no other launch system has had or will have anytime soon (for better or worse).
you know what would be funny if they make a CN tower size rail gun and rail gun materials to the moon to build the same thing LOL
did scientists rule out rail guns ?
"The logic of rocket equation is brutal and inexorable", the NASA rocket scientists would say. "As the performance of the rocket engine decreases linearly, the propellent requirements increases exponentially. Therefore it is imperative to have the highest-possible performance from your rocket engines. The combustion of liquid hydrogen / oxygen is the highest-efficiency chemical reaction, and therefore liquid hydrogen is the only propellant we will consider using for our engines."
All of this was correct, but also wrong. It was wrong in a whole-systems context, because:
A.) Liquid hydrogen is much lower-density than traditional rocket fuels like Kerosene, requiring far larger and heavier structures to carry the same amount of energy, and larger and heavier engines and plumbing and everything else -- and the structural mass of a rocket matters.
B.) Liquid hydrogen will boil off and leak through anything, requiring massive amounts of insulation (again, adding weight), and far stricter operational protocols around the fueled vehicle.
C.) Liquid hydrogen is so cold that it will embrittle and shatter ordinary metals and requires much more exotic and expensive metallurgy.
and finally, D.) The alternative, kerosene, gives you less efficient engines but also much lighter-weight vehicles -- and sure, per that inexorable logic of the rocket equation, you need to use more fuel for the same amount of payload, but kerosene is cheaper than milk so who fucking cares?
Anyhow, the upshot of this is that US rocket scientists spent literally tens of billions of dollars developing hyper-locally-optimised rocketry schemes, most of which failed outright. For the remainder, for every dollar of kerosene they didn't have to buy, they probably spent upwards of $1000 on exotic aerospace hardware. Finally, they gave up and just bought kerosene-based engines from the Russians.
So then there's Elon Musk. And of course there's a ton of brilliant rocket science in the Falcon, but much of the reason for SpaceX's success is because it doesn't optimise solely on the rocket science. They optimise for cost as a whole, and consider factors like design, manufacturing, operations, reusability, etc. to be relevant to the question of cost.
For example: the Falcon 9 would undoubtedly be more efficient if it had a hydrogen-based upper stage. But doing that would cause it to lose most of its commonality with the lower stage, requiring an entirely new design, manufacturing, and operations workforce. Which would cost several orders of magnitude more than the extra kerosene required to fly a "sub-optimal" rocket. The reason they've already cut the price of launch by about 80% vs. (say) the Space Shuttle is because they optimised the whole system, keeping the unique part count and operational complexity as low as possible.
I still sometimes hear old-school rocket scientists grumble about how the Falcon is a less optimised vehicle than the Shuttle, though. They just don't get it. Never will.
Anyhow, that was a tangent. Fascinating to think that wind turbines might be amenable to a similar class of disruption.