Sour grapes, much?
This is why it's important to have different groups of engineers trying different things--you get a chance to pull off things previously thought impossible or prohibitive.
Merlin family vacuum ISP a sedate 311 seconds. COTS and evolutionary based on existing engineering practice. Designed for low cost and reliability, not utter extremes of high performance.
(edited to correct, not COTS. Kept thinking they adapted a RD series design at the start, but I checked and they didn't. Same general story though, lower Isp and lower chamber pressure and very conventional pintle injector design etc its good engineering aka very boring, all their engine design competitors are far more competitive, which is dumb because fuel and tanks are cheap, engine development isn't)
Its very much like comparing the long term reliability of a 2024 specs F1 series racing engine none the less manufactured today in 2014 (or at least they did their best), against the engine in my new Toyota that's in it's 10th mfgr year and is pretty much bulletproof.
In another subthread, someone commented on the Space Shuttle being designed for reuse. Well, sort of, especially at the beginning, at the top, but various ambitions that weren't strictly needed (e.g. the SSMEs, single polar orbit missions) and insufficient budget (turning the reusable first stage every one envisioned before into the kludge of the throwaway tank and massively dangerous SRBs) meant by the time it launched it had no hope whatsoever of meeting those goals.
Add bogus safety calculations, and it was never going to be a "space truck". Space X, on the other hand, seems to understand what this is all about. And unlike NASA isn't burdened by implicit requirements like employing lots of people at the maximum number of sites, or the explicit mission of boosting the South's technical prowess.
That said, I think it's pretty obvious that even after SpaceX successfully lands a Stage 1, they are going to do lots of simulated and real-world testing before using one for any customer cargo.
I can see the day in the future, though, when a first stage that has been launched 2 or 3 times is considered safer than a first stage that has been launched 0 times. I anticipate a bathtub curve of failures.
Some buyers who are risk averse may opt to only use first-launch rockets, while others who are cost sensitive will buy rockets on their last legs. This could revolutionize the entire launch market, and enable many more low-cost satellites to be launched.
You could easily swap the quoted line with this (related to Tesla) and it would still make sense:
"We tried to make an electric car before," ... "Look how long and how much money it took for us to do that, and we still weren't successful for all parts."
There is also a question of will though. IANARS (I am not a rocket scientist), but it seems to me a lot of political investment behind rockets in USA and USSR was military in origin. This meant the rockets and rocket engines they spent most effort on was for single delivery of a warhead with no chance of reuse. Civilian rocketry was just a byproduct of efforts to deliver the bomb. We see this with Russian commercial satellite launches using repurposed ICBMs. If military didn't care about the reuse, the civilian programs would have had to work on it on their own.
I believe that with enough will and advances in technology, engineering problems for reusable rocket engines could be overcome.
SpaceX is intending to break that cycle. If launch costs are low, then you can afford to put cheap payloads into orbit. If the payload fails, just launch another one. If the best chance of a successful launch matters a lot to you, pay a premium to launch on a virgin booster.
However re-usability of the first stage is only going to get them so far. If half the total cost of a launch (pure guess) is in the booster hardware, and they get just 10 launches out of each one, then the total cost per launch will be cut to close to half of what it is now. That's great, amazing even, but it's not 10x cheaper and certainly not 100x. To get down even close to 10x cheaper they need to recover the second stage as well.
I could go into the topic in depth but suffice it to say that politics and bureaucracy have had a stranglehold on NASA manned spaceflight and launch vehicle development since the beginning, and that has had a very negative impact on progress and capabilities. In contrast, unmanned spaceflight at NASA has been, comparatively, much better managed. And there you see a much clearer and sharper continual increase in capabilities, ambition, missions, and so on over time. The missions that would have been acceptable in the 1970s (planetary flybys, for example) would today not return enough science to be justified. Today we have multi-year rover missions on Mars, and we have spacecraft which rendezvous and orbit multiple asteroids using ion engines. Meanwhile, in manned spaceflight we haven't been out of Earth orbit since the early '70s.
Meanwhile, the Falcon 9 stage is primarily just engines, tanks, and frame, with a sprinkling of avionics and RCS plus landing legs for the reusable version. The idea that a system so monstrously simple in comparison to the Shuttle could possibly have the same levels of difficulty of reusability is either extraordinarily naive or propaganda.
To compare, let's see what SpaceX is actually doing: The last, second attempt to recover a booster of Falcon 9 was:
http://aviationweek.com/space/spacex-plans-multiple-reusable...
"While SpaceX remains coy about the exact fate of the modified Falcon 9 first stage, the overall results appear to be encouraging despite the apparent breakup of the booster after it landed in heavy seas."
Previous attempt:
"The latest flight test follows an unsuccessful recovery attempt on Sept. 29, 2013, when the first upgraded Falcon 9 v1.1 was launched from Vandenberg AFB, Calif. Although three of its nine Merlin 1D engines fired to slow the initial descent ahead of a single engine firing for final braking, the vehicle’s spinning motion could not be controlled. As a result of aerodynamic torque, the fuel centrifuged inside the tank, flaming out the engine and sending the stage crashing into the sea."
Oh, also, I should mention how difficult it is to optimize an engine for vacuum as well as sea level operation. In a vacuum you want a high expansion ratio nozzle because that maximizes Isp, but it also lowers pressure. That doesn't work if you have to fight against 1 atm of sea level pressure. That alone is actually a big reason why rockets have multiple stages, because the Isp boost of the high-expansion ratio nozzle on the upper stage is an enormous performance win. One way around the problem is to boost the exhaust pressure, enabling a higher expansion ratio nozzle which can still operate at sea level, but that makes the engine even more complex and difficult to manufacture, let alone reuse.
So you have the SSME which is a high pressure staged combustion regeneratively cooled LOX/LH2 engine optimized for both sea level and vacuum operation. It's a wonder they were reusable to any degree whatsoever within the first several flights. Even so it took until the mid 1990s for the engine design to fully mature and enter a truly operational phase (vs. prototype phase).
Meanwhile, let's look at what SpaceX has on their plate. They have a low pressure (1/3 the psi of the SSME) gas-generator cycle (non-staged combustion) LOX/Kerosene pintle injector engine which uses two different nozzles for sea level and vacuum operation. It's a design with heritage back to an era before color television. It's such a tried-and-true design with so much history that the patents on it expired decades ago. Additionally, in contrast to all the rigmarole an SSME has to go through for each flight the Merlin-1D merely accelerates to a fraction of orbital speed, never leaves the atmosphere, and, in a reuse scenario, is back at the launch site within minutes. No hypersonic atmospheric flight. No re-entry. No bumpy landing. No cold soak. No transition from atmospheric to vacuum operation.
It's a vastly simpler engine which is exposed to vastly less strenuous conditions.
Again, if you think that the Merlin-1D will face anything approaching the problems of the SSME in reusability then you are either extraordinarily ill-informed or you are peddling propaganda.
To be honest it would take something coming out of left field to throw off their reusability plans at this point. At the end of the day the engines just haven't been exposed to very significant adverse conditions during a normal flight, there's no reason to assume the durability would be so much less than on the test stand. More so, the stage is mostly just fuel tanks, engines, and landing gear. There just aren't that many components, and there isn't much opportunity for something to go wrong. They fill and drain the fuel tanks repeatedly, there's no reason to assume they'll suddenly stop working after actual flights. And the overall structure of the vehicle is more than strong enough to withstand several launches and returns.
In terms of results SpaceX achieving reusability will be a big deal. But in terms of the prospects for reusability, the vast majority of the unknowns have now been filled in, at this point it would be more surprising if it didn't work than if it did.
That downplays the viciousness of that environment, "The atmosphere in low Earth orbit is comprised of about 96% atomic oxygen." (http://www.nasa.gov/topics/technology/features/atomic_oxygen...), it's truly corrosive stuff.
I wouldn't be surprised to learn at least one component of the SSME was, or was initially, susceptible to it. A look at more hits from https://www.google.com/search?q=atomic+oxygen+space+shuttle could be instructive.
The Shuttle was required to be reusable as a political goal. However, it was not given the funding it needed to actually accomplish it in any reasonable fashion.
The Air Force put some tough requirements on it, such as the requirement for enough cross-range capability when landing to be able to launch into a polar orbit from Vandenberg, deploy a satellite, and land back one orbit later. This is purely a wartime requirement. No peacetime mission needs this. This required much bigger wings (and thus much more weight), even though the Shuttle never once launched out of Vandenberg, let alone on one of these crazy single-orbit missions.
Politics screwed up other stuff too. The solid rocket boosters, for example, were manufactured on the other side of the country, largely because of Congressional pork. The long and difficult transport process required the boosters to be built segmented, and that design directly lead to the loss oF Challenger.
Similarly, budget constraints dictated the cheaper SRB-plus-external-tank design rather than a more sophisticated and more reusable (and more expensive) reusable booster. This design directly lead to the loss of Columbia.
The net result was that the Shuttle had a very narrow engineering margin. The SSMEs are engineering marvels in terms of how light they are and how much power they put out. But putting out a lot of power for little weight is a really bad plan for something you want to reuse. Reusability means robustness, and robustness means extra weight and less power.
The Shuttle is what you get when you say, "How much will it cost for a reusable launch system? $10 billion? Too much, we'll give you $5 billion." (Numbers in the ballpark but mostly made up for illustration.)
On the other hand, the Falcon 9R is what you get when a for-profit space launch company wants to make more money. It's not a prestige project, it's not a political project, it's not a military project dictated by thoughts of all-out war with the USSR, it's not subject to Presidential grandstanding or Congressional pork. It's just a bunch of smart people thinking of ways to save their customers money and turn a better profit while doing it.
The Shuttle was an extremely ambitious design that did everything differently. Ultimately, everything was too ambitious to be reusable.
Falcon 9R, on the other hand, is deeply unambitious. The rocket is a pretty standard design. They don't even try to use liquid hydrogen for any stage, even though it's theoretically more efficient, instead favoring easier-to-handle kerosene. Their rocket engines are high performance but not on the bleeding edge. And when they decided to go for reusability, instead of building a whole new system with wings and ceramic tiles and all sorts of other extreme innovations, they just said, let's slap some legs on the first stage and give it some extra fuel. It's a completely different approach that pretty much only shares the word "reusable".
I don't think the Shuttle really has many lessons to offer when evaluating the potential of Falcon 9R.
"The Air Force put some tough requirements on it, such as the requirement for enough cross-range capability when landing to be able to launch into a polar orbit from Vandenberg, deploy a satellite, and land back one orbit later."
That's not what I remember at the time this was happening, nor was it e.g. the story in a good study published in Science. Sure, the DoD/intelligence community wouldn't have minded such a capability, but NASA insisted on it to make the shuttle more attractive to them and to help justify the monopoly NASA obtained on these sorts of launches.
Something the DoD didn't like at all, and was partly freed from after the Challenger disaster. Which also prompted a closer look at the safety of Vandenberg launches and the canceling of them.
http://history.nasa.gov/SP-4221/ch5.htm
Quote: "However, it meant that if a shuttle was to execute a one-orbit mission from Vandenberg, it would return to the latitude of that base after 90 minutes in space only to find that, due to the earth's rotation, this base had moved to the east by 1100 nautical miles. Air Force officials indeed expected to launch the Shuttle from Vandenberg, and they insisted that the Shuttle had to have enough crossrange to cover that distance and return successfully."
It goes into quite a bit of detail on the Air Force's involvement and reasoning.
I'd be interested to see them if you had sources that say otherwise.
My sources are what I contemporaneously learned and remembered in the '70s, and that paper in Science (the world's #2 science journal after Nature, not that it wasn't back then very political, just that this claim cuts against their politics). It would have been published in the '80s, very possibly after the Challenger disaster prompted a lot of second looks, but I can't be more specific.
On the other hand, you've given me no reason whatsoever to believe you over them. Your ??? is completely out of line. I merely gave a source for what I said and asked if you had one. I understand if you don't, but don't be surprised if I then don't necessarily believe your claim.
My "???" indicates I think it's quite possible the author's sources lied to him. You're welcome to believe that NASA people, when talking about their greatest and most expensive in every way failure---these decisions killed two complete crews of 7 each---are more honest than I am, but I'm not entirely sure how much company you'll have, the world has seen rather a lot of post-Apollo NASA by now....
(This alone should give one serious pause: https://en.wikipedia.org/wiki/Rogers_Commission_Report#Role_...).
I don't understand your incredulity at my reaction. What exactly did you think was going to happen when you showed up making an effectively anonymous comment saying, "no, that's wrong, believe my 30-year-old memories over the official history"?
"The Space Shuttle was a political football whose design was dictated by the whims of Congress and the meddling of the military first...."
Then you note the military didn't want it, but wanted it to be useful if forced. I would add the Science article specifically addressed the single orbit polar mission, saying the Air Force didn't see a great need for that and would have been happy with gentler flight profiles. It explicitly said NASA insisted on it, and that's consistent with their post-Apollo institutional biases, much the same produced the hot-rod SSMEs.
"Meddling", when it wasn't, qualifies as bashing in my book, especially in the full context of your sentence.
As for my incredulity, maybe start here: https://en.wikipedia.org/wiki/Historiography
I was a History minor in college....
However, if you insist on taking offense at my comment, I'm not going to fight it that hard. I'm not really interested in what offends you.
What I am interested in is some sort of external source for the stuff you're saying. Pseudonymous internet comments from "hga" and vague references to "the Science article" don't count.
Partly true, but keep in mind that was a problem NASA brought on themselves. They chose an overly ambitious design which congress, rightfully in my opinion, balked at. They tried to skip technological generations, which is a nono in R&D and always a very expensive and risky prospect. Instead of coming up with a new idea they doubled down on their fantasy, turning the Shuttle idea into a political juggernaut. And they got their way, they got massive buy in into the Shuttle, by selling it to everyone as the be-all-end-all of everyone's space dreams. It would be all things to all customers: NASA manned spaceflight, NASA space science, commercial satellite companies, even the military. But part of the cost of that political juggernaut was imposition of additional design elements, which brought more compromises. But on the other hand with so many people on board the program had political inevitability and was almost impossible to shut down. The Shuttle would already have been a bit of a turkey relative to its promises but those additional compromises made it one of the most expensive and troublesome launchers in history. But those compromises came about because of the unwillingness of the Shuttle's original backers to consider other options, they made those deals and those compromises and they were forced to live with the consequences.
No all contemporary Russian engines have a much higher Isp. Usually because they use high chamber pressures in the 3000+ psi range. The merlin series runs a mere 1000 psi.
It does win one performance metric of thrust to weight. Little surprise because they might give up 10% of thrust (err, whatever) by running at a lower pressure but obviously running a third of the chamber pressure the engine walls are going to be about a third the thickness and a third the mass, so its a huge win for thrust to weight, knock down the nominator by 10% and the denominator by a factor of 3 and you win. So they do hold a record in this category.
Also lower pressures imply lower temps imply lower thermal load, lower heat shock, lower thermal distortion and thermal related stress on startup/shutdown. It inherently should always outperform a Russian engine WRT restart / reusability unless something has gone very wrong.
Two things make engines un-reusable. One is simple runtime. It seems intuitively obvious that a 1000 psi turbopump is cheaper and more reliable than a 3000 psi turbopump, all things being equal. The other thing that kills reusability is thermal shock effects where need something to be "X" thick to handle the forces and pressures, but the exterior or one side heats up much faster than the inside creating enormous stresses. So low pressure means low temps
THANK YOU! 16 years ago I visited Vandenberg and saw SLC-6, and it has always confused me why they spent so much money building a shuttle launch complex they never used. The argument I always heard was, "well a polar orbit wouldn't make sense for the shuttle" ... but as a wartime option as you describe, now I can see why they did it.
I'm not saying I agree with them, but finally it makes sense why they built and maintained the place, without ever using it.
Without wandering into the weeds of the other subthread, NASA managed to get a mandate that the shuttle would be the sole method of putting US satellites into orbit. Forget about the wartime requirements or desires, this meant that anything the military wanted to put into a polar orbit would have to be done by the shuttle, naturally launching from Vandenberg.
Going from memory of what I've read in the last few days, and of what went into the decision, one factor was the shuttle ended up 20% overweight, and the higher energy requirements for polar orbit launches resulted in a plan for lighter filament-wound instead of steel SRBs: https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Boo... and of course the Challenger disaster helped people to realize just how dangerous the SRB concept was to begin with.
Post Challenger, during the Shuttle fleet's 3 year grounding, a hard look was taken at what was needed to bring SLC-6 up to spec (see end of https://en.wikipedia.org/wiki/SLC-6#Space_Shuttle), and NASA was no longer in a position to force the Air Force to use the shuttle. Which the latter had always thought unwise and the disaster proved to all who could see.
Here's the story:
This business of taking software written for the 8086 processor and porting it to the 80286 normally required completely rewriting the software by hand, often taking years of painstaking effort. It wasn’t just a matter of recompiling the software, of having a machine do the translation, because Microsoft staunchly maintained that there was no way to recompile 8086 code to run on an 80286. Bill Gates swore that such a recompile was impossible. But Drew Major of Superset didn’t know what Bill Gates knew, and so he figured out a way to recompile 8086 code to run on an 80286. What should have taken months or years of labor was finished in a week, and Novell had won the networking war. Six years and more than $100 million later, Microsoft finally admitted defeat.
http://www.cringely.com/2013/03/24/accidental-empires-chapte...
Accidental Empires is a good book.
Can the method used by Scaled Composites, jet lifting a rocket to higher altitude, be employed as a better solution? Why not rocket power the plane portion and go for even higher based launch? Granted some cargo would be lost to weight for control surfaces and wings but recovery should be simpler, a glide path cannot be as hard as landing upright.
That's what the first stage of the Falcon 9 is - a rocket powered boost to enable the second stage to launch from a high altitude.
Terminal velocity in atmosphere is proportional to density and engines are surprisingly dense so you'd need to pack a simply enormous parachute. On the other hand, that big mostly empty tank will slow down the engine for you at very little cost, and its nice to reuse it anyway.
At the terminal area like 500 feet off the ground you could eject the engines and let the tanks explode but thats messy and bad PR and something you haven't added can't fail, so no parachute means no parachute failures, and you'd already navigated under power to within 500 feet of landing, so its simple, cheaper, more reliable, and much safer to just land under power.