On Thu, 21 Jan 2016 15:09:33 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Thu, 21 Jan 2016 10:41:29 -0800, wrote:

On Thu, 21 Jan 2016 18:32:24 +0700, John B.
wrote:

On Wed, 20 Jan 2016 21:22:24 -0600, Martin Eastburn
wrote:

On the ground the tanks leaked. They took off with nominal fuel
and
filled to full after the liftoff and at that level nominal leaking
and at flight altitude there wasn't leaking. It was the design.
At
the flight characteristics, something had to give - design for
flight
to get the full bore ability. If not - altitude would cause
leaks.

But, the SR's flying out of Beal made some short training flights
where they didn't do any in flight refueling. My Sgdn. Commander
who
went through the "up-grade" scheme that gave other pilots the
chance
to fly and theoretically qualify, in the SR, said that he made 30
minute training flights. No refueling.

It wasn't altitude that made the fuel cells leak it was
temperatures.

I think that the take off and inflight refueling routine was more
likely for longer flights. As I said, they took off from Beal and
landed at Kadina, which is a longish flight.

I got to be within maybe 50' from a U2 that landed in a Typhoon.
Made
it's run but the return was limited to our tiny island. They took
off
the wings and took it home in a C-130 as I recall.


I was at two bases where U-2's were stationed and they are a really
close mouthed bunch. Keep the airplanes in the hanger and only let
them out when they are flying :-)

One of the ground crew did tell me that preparing for a flight is a
several hour long procedure as the pilot first makes his preflight
inspection and then gets suited up and has to spend an hour or more
breathing "pure oxygen" to purge nitrogen out of his blood. then he
can go fly.

The ground crew guy said that the pilots get rather short tempered
going through all that :-)



Martin

On 1/18/2016 6:42 PM, John B. wrote:
On Mon, 18 Jan 2016 09:50:43 -0600, dpb wrote:

On 01/18/2016 6:05 AM, Jim Wilkins wrote:
...

I wonder if the pilots really memorize and strictly observe
all those
temperature restrictions and limits. The CIT limit of 427C is
easy if
you're into hot Chevys but the others would confuse me, ...


Years ago I hired a (near) kid fresh out of Air Force who had
served as
air traffic controller at Kadena while the Blackbirds were
stationed
there. He said (amongst other stories) they had only a _very_
limited
time of a few minutes to get traffic cleared and them off the
ground
before they leaked so much fuel they wouldn't have enough to
get to the
refueling rendezvous point. It took getting to airspeed and
resulting
friction heating to expand and seal the tanks, apparently.

I'm not sure about that. While I wasn't in the SR-71 Squadron at
Beal
we did do a certain amount of support work for them, and our
Squadron
Commander even went through the up-grading program and was
qualified
on them. I never heard that they allowed fuel leaks.

But, depending on a lot of things they might have been taking
off with
minimum fuel which would limit their time on the ground.
--

Cheers,

John B.

There is an SR-71 at the Boeing Air and Space Museum in Seattle. It
is
actually a variant, made to carry a drone on top. My brother and I
went on a "tour" of the plane several years ago given by one of the
SR-71 pilots. He told us that the planes did indeed drip fuel when
on
the ground and cool. He told the tour group about how the plane was
fueled for spy missions. The engines the plane used were designed
for
use in a boat, not a plane. But they had the power neded so the CIA
employed designers chose those engines. They still needed many
modifications though. The fuel used for the missions served three
functions. Besides fuel it was also used as the hydraulic fluid and
as
a coolant for the aircraft, the cockpit in particular. Before a
mission a refueling plane was sent up to a high altitude where the
air
was really cold. It then flew around for a time in order to cool the
fuel load. On the ground the SR-71 was lightly fueled with some sort
of conventional jet fuel. When it was airborne the tanks were filled
with the special fuel the plane needed to operate at the high
temperatures it was heated to. The fuel was very hard to ignite. The
pilot told us that just switching over from regular jet fuel to the
special stuff while the engine was running would not ignite the
special fuel. So a small cannister, I think he said it held a pint,
of
some sort of hypergolic fluid was used to ignite the operating jet
fuel. Just a little was used each time the engines needed igniting,
around an ounce I think. The pilot told us that the skin of the
aircraft around the cockpit was heated to 650 degrees, which shows
why
it needed cooling. Other parts of the skin were heated to much
higher
temperatures. Behind the engines, in the exhaust path, the skin was
not a titanium alloy, but was instead some sort of nickel alloy
because this area was heated much hotter than the titanium alloys
could endure. Interestingly, much of the titanium for the skin came
from the USSR. At the time these planes were first built the USA
didn't have the skills yet to make the titanium alloy sheet needed.
So
the CIA purchased the titanium sheet through several devious
channels
so that the USSR wouldn't find out it was supplying the USA. The
pilot
told us that none of the SR-71 aircraft were shot down. He also told
us that the pilots could watch missles on radar approaching the
aircraft and then falling short and missing. Oh, he also told us
that
the top speed was still classified and that the SR-71 was still the
fastest jets made.
Eric

Great description, Eric. Just one correction: The P&W J58 engine was
designed for use in a jet-powered flying boat, not actually a boat.
"J58" is a navy designation, which may have led to some confusion.

I forget the designation of the flying boat, but it was dropped when
submarine-borne ballistic missiles became available. It was to be a
high-speed, low-altitude nuclear bomber.

--
Ed Huntress

https://en.wikipedia.org/wiki/Martin_P6M

Wow, what a cool seaplane. Reading the history, I'm reminded that
flying horizontal stabilizers cause a lot of control problems back in
the '50s.

--
Ed Huntress