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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?
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.
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).
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.
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
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.
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)
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.""
