On Jun 12, 4:57 pm, Len wrote:
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?

NaK would be solid on a cool day, but otherwise
liquid and more practical. Solid sounds more
interesting--and perhaps worth stretching a point
when people want to talk about an unusual plane?
:-)

Len

I should have added that Kelly Johnson was not
averse to turning a clever phrase such as: "We
get all of our thrust out of the inlet; the engine is
just a flow inducer." If you keep your books the
right way, this is actually true. The forces on the
B-70 engine mounts actually reversed at mach 3.

Len



Oren