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Usually simply abbreviated as a RUD, and also sometimes expanded as Rapid Unplanned Disassembly, and being a way of understating that a rocket exploded.

I saw it attributed recently to Elon Musk, but although he has popularized the phrase among the public, when he mentioned it once in a speech I saw he simply said it is how the engineers on the SpaceX team like to refer to such an event.

So what is the history of this phrase, and can it be traced back to the person who came up with it?

Jerard Puckett
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kim holder
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    I don't know for sure, but it would predate Elon Musk's cosmic entrepreneurship or even Kerbal Space Program that most of web searches would suggest. I remember it as rapid unscheduled disassembly, but there are other variants (hard start is used for overpressure during ignition, which is also subtly funny). I wouldn't be surprised if these go as far back as von Braun's or even Goddard's times of rocketry. When you have so many spectacular failures (i.e. "kaputniks") before you finally succeed, you either find comfort in humor or go insane. – TildalWave Jul 18 '15 at 19:06
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    Here's an article from 1991 edition of Cruising World using this term. So it would be used long before that and a common engineering term by then, I can't imagine how it would be coined for the purpose of describing torn boat sails. – TildalWave Jul 18 '15 at 19:22
  • A smartass, I'd bet! – Ezra Bailey Jul 18 '15 at 19:56
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    It was in use when I started my aerospace career in the early 80s. – Organic Marble Jul 18 '15 at 21:31
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    I was going to say that it is at least 20 years old, but @OrganicMarble wins. "Unscheduled" is the proper expansion. – Mark Adler Jul 19 '15 at 04:35
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    I asked David S.F. Portree, a spaceflight historian and since recently also a Space Exploration SE denizen, and he thinks it might have been used when an S-IVB stage ruptured on an MSFC test stand c. 1965, and that it would reference a specific event. I tend to agree, it could be related to the Saturn 503 S-IVB explosion at the Douglas Sacramento, CA and subsequent MSFC-appointed investigating board's Disassembly Activities (chaired by Kurt Debus, KSC) in 1967. – TildalWave Jul 19 '15 at 04:46
  • A Google search by date of the phrase turns up some examples from 2001, nothing earlier. That doesn't mean it wasn't used before 2001, of course... – Hobbes Jul 20 '15 at 11:01
  • @Hobbes: I looked into that as well, the 2001 entries weren't really 2001. More likely the earliest date on the internet was 2011 or so, if I remember right. – PearsonArtPhoto Jul 21 '15 at 17:20
  • I would look into British sources, because I found a fairly similar term "catastrophic self-disassembly" cited here: http://library.sciencemadness.org/library/books/ignition.pdf on page 123 (page 123 as stated by the text on the page, not what the pdf says), and it's attributed to the British. – DrZ214 Jul 23 '15 at 03:26
  • Yes, quite a similar term, and the book dates from 1972 - "when you have a turbine spinning at some 4000 rpm, and the clearance between the blades is a few thousandths of an inch, and this sticky, viscous liquid deposits on the blades, the engine is likely to undergo what the British, with precision, call 'catastrophic self-disassembly.' " Though the Saturn IVB MSFC test predates that and could be the source of both. – kim holder Jul 23 '15 at 14:21
  • Incidently, i emailed the person who looks after the MSFC archives, after not being able to find the 'Disassembly Activities' report, and they promptly responded that they couldn't find anything in the archives and they'd never personally heard the term. :-/ – kim holder Jul 23 '15 at 14:25
  • The earliest I could find it was in a book entitled "Rocket Religion", https://books.google.com/books?id=Weg1WPmzupkC&pg=PA4&dq=Rapid+Disassembly+rocket&hl=en&sa=X&ved=0CCIQ6AEwAWoVChMIm-b8nIb0xgIVyZoeCh2-mAJi. Rapid, unintended disassembly – PearsonArtPhoto Jul 24 '15 at 15:09
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    @briligg That's odd, because I can find some with a simple web search, e.g. in Saturn Illustrated Chronology or Apollo Spacecraft Chronology. – TildalWave Jul 24 '15 at 15:41
  • Possible source of 2011 boost in this term: https://rocketry.wordpress.com/2011/11/13/rocketry-euphemisms/ –  Jun 16 '16 at 20:05
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    I can confirm @organic-marble ‘s etymology; I, too, learned this as an engineer in the 80’s. – TransferOrbit Oct 21 '17 at 01:35

7 Answers7

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So far as I can tell, it was first a saying used by military personnel as the phrase "Rapid Unintentional Disassembly", for a phrase when a gun broke apart if you misused it. This was used by a book for Navy Personel in 1970, so I suspect it was in use for a while before then. This seems to have evolved from that phrase somewhat over the years. The earliest I can find it in rocketry specifically was the book entitled "Rocket Religion", copyright 2002, again with the same phrasing.

It seems to have exploded in popularity around 2011. I can't tell the exact source, but it was either Elon Musk or Kerbal Space Program, most likely.

PearsonArtPhoto
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    By "gun" do you mean rifle or artillery piece? – Jerard Puckett Jun 16 '16 at 01:18
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    The chapter is entitled "Small arms and Machine Guns", so something smaller than artillery. Unfortunately I don't have access to more of the book... – PearsonArtPhoto Jun 16 '16 at 01:19
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    I love that Musk and KSP are equally as likely to have migrated this to rocketry. :) – jklemmack Sep 18 '17 at 16:33
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    My impression is that KSP is more responsible for "lithobraking" while Musk popularized "RUD". – lamont Dec 08 '17 at 19:47
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    @lamont, "lithobraking" was used to describe the Mars Pathfinder landing system, so it pre-dates KSP by at least 14 years. Ablative lithobraking, on the other hand, appears to be a KSP original. – Mark Aug 10 '19 at 19:18
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    Went looking and I couldn't find any NTRS articles that mention it or find it on google ngrams but this thread from 2010 mentions it which predates KSP. But the discussion I was responding to was about when the terms "exploded in popularity" (tangential to the OPs question about what the origins were). Musk didn't invent RUD, but he popularized it, KSP didn't invent lithobraking but I think it popularized it. – lamont Aug 12 '19 at 02:58
  • exploded in popularity :D – user985366 Jun 18 '20 at 09:40
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Here's a reference from 1967 in "The MAC Flyer", Volume 14, Issue 5. This appears to be a periodical of the US Military Airlift Command. I have not been able to locate full text (but would certainly appreciate updates).

... an interface with hazardous conditions which could preface an unscheduled disassembly, ...

Resuna
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When I started at McDonnell Douglas in 1977, the term was RUDE, as in a "RUDE rocket".
Rapid, Unplanned Disassembly Event. It was listed in a book full of industry acronyms I was required to read during my first two weeks. Bit was another term defined therein: Binary digIT.

Carl Ketcham
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There is a number of expressions which convey much the same meaning. And it is hard, if not impossible, to find the originator.

The expression I heard first was 'spontaneous rapid disassembly event' which according to New Scientist Feedback column (July 2004) is used to describe explosions in scientific papers.

Other expressions

  • Fire : uncontrolled thermal event
  • Bursting : unplanned loss of containment
  • Crash : deconstructive deceleration
Tarjei Jensen
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7

I thought that I saw the term used while reading about the early history of JPL many years ago but I can't find the article now. I do see that that JPL started in the 1930's: https://eands.caltech.edu/launch-points, so maybe researching old archives from JPL in those years could turn something up.

I did find this: https://history.nasa.gov/monograph45.pdf where on p.42 it states, "I deemed it “pre-unplanned disassembly” at the time." (Gerald R. “Jerry” Pfeifer?) It's not 100% clear when "the time" was but it seems to be early 1960's and the way he says it makes it sound like it was his own phrase. Same paper p.48 he says, "managed to cause another unscheduled disassembly of the facility" but it's not clear if that was the term he used at the time of the disassembly many years ago or just while giving the lecture about that time (2006). If he's still around maybe someone should ask him before it's lost knowledge.

infinitesimal kitten
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  • That is a great book you've linked to, i will definitely be reading it all. That passage is good circumstantial evidence, but i agree the only way to settle this is to root through archives and ask people who were involved and are still with us. – kim holder Feb 20 '18 at 17:43
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The acronym was in use in Navy F-14 squadrons in the mid-70’s. The Pratt & Whitney TF30-P-414A engines had an unfortunate habit of shedding blades. The repairs, which involved really tedious and carefully sequenced tear down and inspections, were occasionally followed by engines failing and shredding themselves during full-power post-assembly tests. I remember an Engine Chief explaining that he preferred “rapid unplanned disassembly” to the other kind when the engine “was a lemon”. (I’ve omitted some chiefly adjectives)

Bob Jacobsen
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I've found something like this in famous book "Ignition! An informal history of liquid rocket propellants" by J.D.Clark, 1972.

" And when you have a turbine spinning at some 4000 rpm, and the clearance between the blades is a few thousandths of an inch, and this sticky, viscous liquid deposits on the blades, the engine is likely to undergo what the British, with precision, call "catastrophic self-disassembly.""

DDT
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