

The X-15, the fastest manned aircraft ever made - jonbaer
http://sploid.gizmodo.com/the-best-photos-of-the-x-15-fastest-manned-aircraft-ev-1675268839

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Luyt
From the book Ignition!
([http://library.sciencemadness.org/library/books/ignition.pdf](http://library.sciencemadness.org/library/books/ignition.pdf))

 _" But something more potent than alcohol was needed for the X-15 rocket-
driven supersonic research plane. Hydrazine was the first choice, but it
sometimes exploded when used for regenerative cooling, and in 1949, when the
program was conceived, there wasn't enough of it around, anyway. Bob Truax of
the Navy, along with Winternitz of Reaction Motors, which was to develop the
50,000 pounds thrust motor, settled on ammonia as a reasonably satisfactory
second best. The oxygen-ammonia combination had been fired by JPL, but RMI
really worked it out in the early 50's. The great stability of the ammonia
molecule made it a tough customer to burn and from the beginning they were
plagued with rough running and combustion instability. All sorts of additives
to the fuel were tried in the hope of alleviating the condition, among them
methylamine and acetylene. Twenty-two percent of the latter gave smooth
combustion, but was dangerously unstable, and the mixture wasn't used long.
The combustion problems were eventually cured by improving the injector
design, but it was a long and noisy process. At night, I could hear the motor
being fired, ten miles away over two ranges of hills, and could tell how far
the injector design had progressed, just by the way the thing sounded. Even
when the motor, finally, was running the way it should, and the first of the
series was ready to be shipped to the West Coast to be test-flown by Scott
Crossfield, everybody had his fingers crossed. Lou Rapp, of RMI, flying across
the continent, found himself with a knowledgeable seat mate, obviously in the
aerospace business, who asked him his opinion of the motor. Lou blew up, and
declared, with gestures, that it was a mechanical monster, an accident looking
for a place to happen, and that he, personally, considered that flying with it
was merely a somewhat expensive method of suicide. Then, remembering something
he turned to his companion and asked. "By the way, I didn't get your name.
What is it?". The reply was simple. "Oh, I'm Scott Crossfield."_

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dbarlett
NASA published a comprehensive (if a bit dry at times) ebook, _X-15: Extending
the Frontiers of Flight_ [1] that covers the development and test program. If
you're ever near Dayton, Ohio, the National Museum of the USAF has X-15A-2 [2]
and an XLR99 [3] on display.

[1]
[http://www.nasa.gov/connect/ebooks/aero_x15_detail.html](http://www.nasa.gov/connect/ebooks/aero_x15_detail.html)

[2]
[http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id...](http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=556)

[3]
[http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id...](http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=890)

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forgingahead
Very cool. Also if you want a wider view of the content, fire up the web
inspector console and enter the following:

$(".main-column").attr('class', 'large-12 columns main-column');$(".hide-for-
medium-down").remove();

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tdicola
That reminds me, earlier this month I saw a great PBS Nova episode about Neil
Armstrong's life: [http://www.pbs.org/wgbh/nova/space/first-man-on-
moon.html](http://www.pbs.org/wgbh/nova/space/first-man-on-moon.html) It
talked a bit about the X-15 and some crazy situations Neil got into flying
them, like skipping off the top of the atmosphere at supersonic speeds.

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bane
A good movie about aerospace and the origins of the U.S. space program (it's
also a book) is "The Right Stuff".

I don't think the X-15 is in it, but it can give you an idea of what the times
were like
[http://www.impdb.org/index.php?title=The_Right_Stuff](http://www.impdb.org/index.php?title=The_Right_Stuff)

It's still worth a watch today.

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rst
The X-15 was also a milestone in the development of flight control systems --
in some phases of flight, the aircraft was too unstable to be easily
controlled by a human pilot, and on most flights, it had machinery massaging
the pilot's control inputs.

"Digital Apollo", by David Mindell, has a chapter on this, before it gets into
the space program proper.

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mgl
Spot on comment: [http://sploid.gizmodo.com/jesus-what-happened-to-america-
our...](http://sploid.gizmodo.com/jesus-what-happened-to-america-our-
grandparents-where-1675272285)

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gre
Besides the space shuttle?

~~~
gilgoomesh
Yeah, the terminology isn't well defined by the article. The X-15 is the
fastest, manned, suborbital craft ever built.

~~~
ZanyProgrammer
Some of the X-15 pilots got astronaut wings.

~~~
noer
They got astronaut wings for Shuttle/Apollo/Skylab/Gemini(?) missions though,
not specifically for their X-15 flights right?

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spain
I had always though the SR-71 was the fastest airplane, and it turns out I'm
right (sorta). The X-15 isn't an air _plane_ , apparently (hence why it's only
referred to as an air _craft_ ). I'm not sure why but probably because it's
just a rocket and it doesn't actually "breathe air", nor does it seem to be
able to take off on it's own?

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eterm
Some videos here:
[http://www.dfrc.nasa.gov/Gallery/Movie/X-15/index.html](http://www.dfrc.nasa.gov/Gallery/Movie/X-15/index.html)

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seivadmas
Must have been utterly terrifying to pilot that thing... the entire aircraft
is basically one gigantic fuel tank with a tiny space for a seat at the front.

~~~
JoeAltmaier
I imagine the danger of faster airships is like falling out of successively
higher windows. After you reach the 3rd storey it'll kill you, so it quits
having any meaning.

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listic
What did we* need such hypersonic rocket planes for and why did we stop
improving them?

*we as a species

~~~
ZanyProgrammer
Vietnam? The belief that low, slow and stealthy would win the day vs high and
fast? Look at how many people claim that SAMs won out against the B-70
Valkyrie (basically, a heavy bomber analogue to the SR-71).

~~~
BashiBazouk
More likely high and fast is the answer, it's just ICBM's are faster and go
higher than hypersonic rocket planes...

