On May 13, 5:05 am, "Kurt R. Todoroff"
wrote:
In article
,
"Ken S. Tucker" wrote:

On May 13, 1:03 am, frank wrote:
On May 12, 5:13 pm, Andrew Swallow wrote:

Let me guess, corrections invited.
Today, software and computer enhanced flying is
well known to a military pilot. (The rumor that the
F-22's crossing the International dateline caused
the computer - via software glitch - to crash is a
typical example).
In a sense, software removes pilots burden.
When was software first used? I'm guessing it was
1st used to automatically control the F-111 wing
sweep.
Ken

Ken,

The pilot commanded the F-111 wing sweep position via a lever that was
mounted underneath the left canopy rail. It hung underneath the rail
and was hinged to flip up (outboard) to stay out of the way. The pilot
would move his left hand from the throttles up to the handle, grab it
and rotate it down, then push it forward or pull it back. Forward
equals wings move forward, back equals wings move back. When the handle
was stowed in the outboard spring loaded position, it was friction
locked from moving forward or back. The wing sweep control handle was
connected via manual cable (not electrical cable) to the high-lift
control system, which in turn controlled the wing sweep position. Wing
sweep position was directly proportional to wing sweep handle position.
The two hydraulic systems provided control power to move the wings. The
wing sweep actuator was a non-reversible system that prevented the wing
sweep position from being affected by airloads. The forward position
was 16 degrees leading edge sweep. The aft position was 72.5 degrees
leading edge sweep. The wings moved at 3.8 degrees per second. The
aircraft placard G limits were -3.0 to +7.33 symmetric when the wings
were stationary. This were later changed to -1.5 to +7.33. During wing
sweep, the placard G limits were 0 to +4.0 symmetrical. Assymmetric G
during wing sweep was prohibited.

The F-14 Tomcat used a more sophisticated wing sweep system. The
pilot's right throttle contained a five position thumb switch (button)
on the inboard side which was very similar to the trim button on the
stick except that unlike the trim button which was spring loaded to the
center position, the pilot could place the wing sweep button in any of
the five positions. The positions we

Forward: Sweep wings forward
Aft: Sweep wings aft
Down: Sweep wings to sixty degrees (I think)
Up: Autosweep
Center: No command

In the Autosweep mode, the Central Air Data Computer (an analog device)
commanded the wing sweep position according to Mach number, using a
pressure altitude bias. Furthermore, regardless of wing sweep mode, the
CADC would not allow the wings to be over-sped. If the pilot manually
commanded the wings forward, the CADC would stop the wing sweep movement
when they reached the computed Maximum Safe Mach value. If the pilot
left the wing sweep control in the center (no command) at takeoff
instead of up (Auto) then the CADC would start to sweep the wings aft
during aircraft acceleration to prevent overspeeding the them. The
forward position was 20 degrees leading edge sweep. The aft position
was 68 degrees leading edge sweep. The wings moved at 15 degrees per
second. The aircraft placard G limits were -1.5 to +6.5 symmetric even
during wing sweep. Grumman improved on the F-111's wing box to gain
this capability, unfortunately at the expense of a substantial amount of
extra weight. Variable geometry wings proved to be a great asset to the
F-111 in the interdiction/strike role. In my opinion it provided no
benefit to the F-14 in the A/A role. The F-15A empty weight was 28,500
pounds. The F-14A empty weight was 40,000 pounds. Most of this was due
to the VG component of the aircraft. These two aircraft are nearly the
same length.

The F-14 used a simple fly-by-wire throttle. The interconnect between
the throttles and the engine fuel controls was electrical. The F-16
uses a similar FBW throttle system, that compliments its FBW flight
control system which which GD borrowed from the F-111. GD used the
Vark's triple channel FBW flight control system, added a fourth channel,
and added a few more features (ie. limiters, some of which were
eventually added to the Vark's FBW FCS) and then used it in the F-16.
Kurt Todoroff

Thanks Kurt, We (wife and I) studied your post carefully,
For me, you put me into the F-111 and F-14 cockpit.

In the early 70's there was a kind of renaissance in
aviation, (I was in the bearing business, SKF), and the
F-111 was maturing, as were the F-14, F-15, and the
fighter competition, F-16 and F-17 was hot stuff.
The B-1A was suffering from bearing problems, the
C5-A had wing strength issues.

I agree with your F-14 thesis, the VG weight penalty
was not worth the performance gain, especially in
view of the F-18, but also recognize the subtle diff
where the F-111 and then B-1 is concerned, as you
point out, in the long strike mission.
Regards
Ken