On Mon, 22 Sep 2014 22:21:30 -0400, Ed Huntress
wrote:

On Tue, 23 Sep 2014 08:19:55 +0700, John B. Slocomb
wrote:

On Sun, 21 Sep 2014 21:57:03 -0400, "Jim Wilkins"
wrote:

"John B. Slocomb" wrote in message
...
On Sun, 21 Sep 2014 11:09:18 -0400, "Jim Wilkins"
wrote:


The Titanium for Vietnam fighter jets came from the USSR, through a
tortuous network that concealed its final destination. The Market
Basket article I referenced told how they used intermediaries to buy
up land to avoid revealing their intent and driving up the price.
Those are examples of old tricks to deceive market, CIA, KGB, NSA
et.al. analysts looking for patterns.


Out of curiosity, what Vietnam fighter jets was titanium used on?
I ask as I spent several years servicing the various fighter jets
that
were used in Vietnam and I don't remember any that used titanium.
The
first airplane that I saw in USAF use that used any quantity of
titanium was the SR-71, hardly a Vietnam fighter jet.
--
Cheers,

John B.

http://www.tomcattersassociation.org...h-titanium.htm

I can't tell titanium from stainless unless I can pick it up and feel
the weight.

-jsw

Interesting. And I did work on F-4's and one of the problem areas was
the stabulators. Although not the skin but the pivot.

The major difference in using titanium is that it is complicated to
weld and it work hardens very rapidly. In the early 1970's the USAF
certification test for titanium was still welded in an inert
atmosphere box. I had an extra day at my last certification test and
the Instructor asked if I wanted to try titanium and the biggest
problem was trying to work inside the box using the attached gloves.

The sheet metal guys used to curse the stuff as drilling rivet holes
was a bit of a struggle as the stuff was forever turning diamond hard
if you let the drill slip the tiniest bit.

We worked on the SR's a little when they were first transferred to
Beal and they didn't yet have their full compliment of workers and no
one was sorry when they got fully manned and we could go back to our
"regular" airplanes :-)

In addition to the SR-71, the F-111 had titanium skin. I was told that
the original method for welding it was electron-beam, performed in a
vacuum. I think the atmosphere came later.

I don't know about the "F-111" but I was part of the test detachment
for the FB-111 and I don't remember that any of the skin where there
was access panels being aluminum. Certainly the panels behind the
cockpit module were aluminum and the fuselage skin around the exhaust
outlets was aluminum -- the reason I know was that the screws in the
panels behind the cockpit had left hand threads and the Airframe guys
used to try to take them out with an air screwdriver and stripped the
plate nuts off, and the aft fuselage fairing because a pin that held
it on jammed and we had to cut a hole in the skin to beat it out. The
"splitter plates" that separate air flow between the fuselage and the
engine inlets was aluminum and the aft wing spar was aluminum as we
had to come up with repairs for both those items.

You can't use aluminum above Mach 2, roughly. The limit is around 300
deg. F, which was the result of skin friction at high speeds. It loses
too much strength above that temperature. That's what limited the
Concorde's speed, too; it was aluminum, for cost. Above that you need
titanium or steel. The Russions, despite their considerable expertise
in metallurgy and a good supply of titanium, couldn't weld it. So the
Mig 25 (Foxbat) was skinned and framed in steel.

While I was at Edwards with the FB-111 I worked in the "Base Shops"
for a while and some guys came in with a nose gear, obviously from a
small airplane. It had no data plates or other obvious markings on it
and the question was how to get it apart. I got called in because I
was Air Force and the rest of the shop was civilians, so I got to look
it over pretty closely.

It was a complete nose gear strut with the trunions on the top and the
axle on the bottom. Obviously an Oleo strut, there was a high pressure
air valve in the top. But no way to disassemble it. It appeared that
it was somehow assembled and then welded together and no way to take
it apart.

I asked the guys "what kind of airplane did this come off?" and got no
answer. Based on the timing I suspect that it was the nose gear from
the MIG that was flown to Taiwan and then sort of disappeared.

I never worked on small airplanes and I don't know how much nose gear
problem they have (the big ones don't have much) and the strange nose
gear was pretty light. Maybe a steel tubing, welded together, change
the whole thing, nose gear makes sense. A lot of the things the
Russians did that were condemned as "crude" actually made very good
sense.
--
Cheers,

John B.