On Jun 12, 1:21 pm, Oren T wrote:
On Jun 12, 12:58 pm, "Ed Ruf (REPLY to E-MAIL IN SIG!)"

wrote:
On Mon, 11 Jun 2007 12:03:33 -0700, in sci.space.policy Len
wrote:

technology. As I understand it, even a complicated
beast like the SR-71--with hydraulic "fluid" that was
solid at room temperature--was flown twice in the
same day. IIRC, they only did it once, because of
cost considerations--not techinical difficulties.

I thought the SR-71 used its JP-7 fuel for hydraulic fluid? JP-7 isn't
anywhere near a solid even at winter temps in Hampton, VA where we have
several drums of if out back behind our facilities.
--
Ed Ruf )

A quick web search shows it had two hydraulic systems: one for the
engines which used the fuel as working fluid and another using
something solid at room temperature. Len suggests it may have been NaK
but a eutectic is liquid at STP (mp -12.6 C). Perhaps it was straight
sodium?


Do you have an actual cite? (sight /pun)

The one source I could locate:
http://www.blackbirds.net/u2/c_bennett/bbird-03.html

" Another problem occurred when trying to pin-point leaks. With oil,
fuel, and hydraulic fluids being the same color, it was difficult to
actually see what was leaking. "

The same source, despite noting that the engines had to be heated in
order to thin the lubricating oil significantly fails to make any such
notation about the hydraulic system. The online version of the SR-71
flight manual (http://www.sr-71.org/blackbird/manual/) fails to
mention solid or unusually thick hydraulic fluid as well.

In fact, I could not find _any_ source that specified the hydraulic
fluid was a solid at room temperature. (Though I did find one that
claimed it was a powder.)

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL