Antares apocalypse: Orbital points finger at turbopump FAIL Orbital Sciences says it's probably going to ditch the Russian-made Aerojet Rocketdyne AJ26 engines it has been using for its Antares launchers. The company says preliminary analysis of the telemetry from its failed launch in late October suggests that a turbopump probably failed in one of the two first-stage main engines. …
Watching the video of the launch last week, it appeared to me the spacecraft was doomed almost from the moment the rocket engine started up. There was an abnormal-looking flash in the exhaust whlie the rocket was still on the pad. I wouldn't have been able to pinpoint the turbopump as the cause, though.
The whole point of nuclear missile submarines is to enable a second strike. We, the USA and France had them. This was kind of the point of Mutually Assured Destruction. Yes, we would have been fucked, but so would the USSR.
Of course capability does not necessarily and certainly lead to intention. Bomber captains are a special breed.
Designed sure. But not built. That's one crucial difference. 1960s quality control technology was worse anyway, let alone compared with Soviet-built stuff from the era.
I'd have thought that they'd have to go to so much effort to check and refurb these engines, that it would be as cheap to build them new anyway. Given I believe they have a license to do so.
Imagine if an airline flew a 747 with some engines they found in the corner of an old hangar from 40 years ago, with no proper storage paperwork. I suppose, to be fair, that this is the sort of thing people do with historical aircraft. But they only risk their own lives, fly under strict rules at airshows, and don't carry $200m of other peoples' cargo.
The difference is that if 1/4 of the engines on a 747 blows up, the damage is contained, and the plane will be able to continue in flight -- or from point of no abort during takeoff -- and land again safely(*). Same is true of 1/2 engines on a twinjet.
(*) Design 100% sure. Reality 99.something% sure. Would prefer not to be on the flight with the exploding engine.
The difference is that if 1/4 of the engines on a 747 blows up, the damage is contained, and the plane will be able to continue in flight -- or from point of no abort during takeoff -- and land again safely(*). Same is true of 1/2 engines on a twinjet.
But I guess it's 100% untrue for a tri-jet; remember the crash at O'Hare in the late 70's when a wing engine fell off a DC-10? Sucker flew like a rock.
Wasn't that the DC10 disaster that the manufacturer blamed on an airline using a fork-lift truck to lift engines on and off the wing? The engine didn't just fall off, it took large chunks of the wing with it, when the whole structure failed.
I believe Boeing made a comment to the effect that they also don't recommend installing engines using fork-lift trucks, but they make their wings and engine pylons strong enough to take it!
Anyway, it wasn't an engine blow-up. Google "Thompson Manchester Airport bird strike" for good video of a very scary take-off. (Wasn't a blow-up, but I don't imagine that the engine which ate the bird was generating much thrust after it did).
An engine failure while the plane is on the runway but committed to take-off is the worst case. There's quite a large scope for fatal pilot error should that happen. The Thompson jet was already in the air -- slightly less bad.
The rocket motor design is old by today's standards and rather persnickety but in this case, I wouldn't think the age of the technology was the problem. A turbopump failure is one of things that can go wrong with any rocket. The big issue is "why?". Did someone cut a corner on the bearing spec? Dirt in system? Turbine disintegration? Possible failure in the combustion chamber caused a backup of pressure into the pump?
I'll add that it's possible that this motor had been in storage for 40 years and something got missed in the rebuild/refurbishment.
Everyone is missing the fact that the engines have been re-furbished by AeroJet. So the misconception that they came out of a 40 year old factory untouched isn't realistic.
Its a single shaft turbo pump so it drives fuel and oxidizer, the comentard that poked at my comment of an engine failure cant eat that as I called it as such.
The interesting thing is what are Orbital going to use for an replacement. They cant get engines from Energia as these are all contracted to RocketDyne/ULA. Maybe they can graft Cygnus to a 60 year old Soyuz :-)
If it's just cargo (human spaceflight DOES NOT like rockets you can't shut off if an anomaly occurs), ATK was offering all-solid boosters that can fill the role and give Orbital time to bring a new engine online. Maybe the AR-1 that Aerojet Rocketdyne is offering, that'd put them up pretty well.
Really, as soon as this Antares blew, the AJ-26 was dead and the program was on the ropes. Combined with the test stand explosion due to corrosion cracking / old metal, their entire supply of engines is now suspect, and testing didn't catch either fault. It's like the Minotaur fairing issues but from the other direction.
You missed one more. Pulling the dusty files out of the dark corner of the brain where they were confined after I got my Chemistry MSc and went to the dark side of IT: Many light metal alloys are not steel, they change with time and some of them quite a lot. Some of it is change in crystalline structure, some of it is oxidation, some of it is dark magic which noone understands :)
Most Al, Ti, Mg, etc alloys (as used in space tech from half a century ago) would have undergone a considerable change of mechanical properties over 50 years (not necessarily bad by the way, Al alloys generally become less fragile and more plastic with age). What would have been well within the tolerances 60 years ago, may not necessarily be usable today. If the pump has any elements made out of Titanium or Al alloys that would have been the prime suspect in my book.
IMHO - this is the biggest FAIL in the Orbital idea. It is not a rocket technology fail, not a control tech fail, not a refurb fail. It is a material sciences fail.
"The big issue is "why?"
The press-release said "a turbopump-related failure" which is very vague and it would be really interesting to know exactly.
It is was indeed a turbopump failure then most likely it's either due to pitting corrosion or general deterioration of the crystalline structure of the metal due to aging. It would be downstream of the pump - in the outlet casing or even in the feed lines - a burn-through resulting in a massive pressurised fuel leak. It still does not rule out a failure in the new articulated piping made by Aerojet.
In any case, continuing using these engines is out of the question for Orbital as it will present an unacceptable political and reputational risk for the company.
There can be lots of causes of turbopump failure, but the NK33 is particularly vulnerable because to get its high specific impulse it puts O2-rich turbopump exhaust into the combustion chamber. That means that if anything goes wrong with the flow of the very-hot gas/liquid exhaust flow the turbopump casing can burn through in a small fraction of a second leading to catastrophic thrust reduction and probably an explosion of the remaining fuel/oxidizer.
Yes, the engines were "refurbished".
But, consider that:
- They were designed and built in the 1960's, for the failed lunar mission by the Soviet Union (the only flights of which spectacularly exploded)
- They were refurbished and renamed by a Ukrainian company in the 1990's
- Orbital bought some of the limited supply of them, because they had no engines or rockets of their own.
- Orbital outsourced all other aspects of their efforts. They were at best a systems integrator.
When you put these facts together with Orbital's lack of experience in rockets, you have to wonder why NASA awarded them a contract in the first place.
"When you put these facts together with Orbital's lack of experience in rockets, you have to wonder why NASA awarded them a contract in the first place."
Anyone looked at Orbital's board/investor list? Otherwise elements of this quote spring to mind-
Rockhound: You know we're sitting on four million pounds of fuel, one nuclear weapon and a thing that has 270,000 moving parts built by the lowest bidder. Makes you feel good, doesn't it?
And to think our local fireworks display was boasting about the £2,500 they spent last night.
Mind you, their wizz-bangs lasted longer. And with more colours. And they had those cool ones that whistle as they spiral, which was more than that Antares did...
I dunno. Watching the video, I'd say they had plenty of those spiraling things flying off in all directions at Wallops. They were probably whistling too, but they had to compete with the shockwave of a couple of hundred tons of kerosene and liquid oxygen exploding all at once. I bet you didn't have that at the local bonfire night :-)
Remember seeing a documentary about the Russian moon programme some years ago. They went for a design of rocket motor with some kind of very powerful but not-reliable-enough turbo pump system. It always blew up and they never got to the moon. Amazed that anyone bought the left-overs second hand?
The Engines that came in from the Cold I think it was called.
Most closed-cycle (turbopump exhaust fed into combustion chamber) engines run the turbopump fuel-rich which gives lower pressures and temperatures. The NK33 does the opposite by running the turbopump oxidizer-rich. The result is high specific impulse engines where any kind of small problem with the turbopump operation can lead to the steel casing of the pump melting and burning through in roughly 100ms. The casing is roughly an inch thick piece of very tough hardened steel.
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