Can F-15s making 9G turns with payload?

(Walt BJ) wrote:


We used 4G as a standard pull-out in the F4, 5g if we were pressing
for greater accuracy. I managed to pull 8 once in an extremity (we
were getting hosed) and nothing fell off.

Got this among a list of quotes from a reasonably erudite fighter
pilot:

"The aircraft G-limits are only there in case there is another flight
by that particular airplane. If subsequent flights do not appear
likely, there are no G-limits."

Makes a lot of sense to me.



Ed Rasimus
Fighter Pilot (ret)
***"When Thunder Rolled:
*** An F-105 Pilot Over N. Vietnam"
*** from Smithsonian Books
ISBN: 1588341038

On Thu, 18 Sep 2003 13:47:22 GMT, Ed Rasimus
wrote:

(Walt BJ) wrote:


We used 4G as a standard pull-out in the F4, 5g if we were pressing
for greater accuracy. I managed to pull 8 once in an extremity (we
were getting hosed) and nothing fell off.

Got this among a list of quotes from a reasonably erudite fighter
pilot:

"The aircraft G-limits are only there in case there is another flight
by that particular airplane. If subsequent flights do not appear
likely, there are no G-limits."

Makes a lot of sense to me.



REad of a Skyray pulling 12 Gs and wrinked the wing. Don't know if it
ever flew again. And also of a Tomcat that did a NEGATIVE 8+ (they
didn't have a choice). I think the Tomcat flew again.

"Scott Ferrin" wrote

REad of a Skyray pulling 12 Gs and wrinked the wing. Don't know if it
ever flew again. And also of a Tomcat that did a NEGATIVE 8+ (they
didn't have a choice). I think the Tomcat flew again.

Humans aren't rated for -8 G's for over 1 second :-)

In article ,
Scott Ferrin writes:
On Thu, 18 Sep 2003 13:47:22 GMT, Ed Rasimus
wrote:

(Walt BJ) wrote:


We used 4G as a standard pull-out in the F4, 5g if we were pressing
for greater accuracy. I managed to pull 8 once in an extremity (we
were getting hosed) and nothing fell off.

Got this among a list of quotes from a reasonably erudite fighter
pilot:

"The aircraft G-limits are only there in case there is another flight
by that particular airplane. If subsequent flights do not appear
likely, there are no G-limits."

Makes a lot of sense to me.



REad of a Skyray pulling 12 Gs and wrinked the wing. Don't know if it
ever flew again. And also of a Tomcat that did a NEGATIVE 8+ (they
didn't have a choice). I think the Tomcat flew again.

That would have been Bob Rahn, in one of hte prototype XF4Ds,
discovering thr Ford's pitchup tendency when pulling G while
decelerating through the transonic range. (An F4D wasn't on most days,
supersonic in level flight. Clean, with a good airplane, maybe, but
otherwise, not. It could be dived to Mach 1.2-1.3 fairly routinely,
though). Since one of teh Skyray's innovations was a rather unique
constuction method using a very thin skin over lots of small stringers
and spars, the airplane was not only well and truly bent, but ended up
wrinkled like a prune. (It's worth noting that one of the changes
that occurred when turning the F4D Skyray into the F5D Skylancer was a
more conventional type of construction.)

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

"Ed Rasimus" wrote

"The aircraft G-limits are only there in case there is another flight
by that particular airplane. If subsequent flights do not appear
likely, there are no G-limits."

They even include a chair where you can give it back to the taxpayers
anytime you like...

The F4 wingtips cracked from vibration, not G. However, G set up the
vibration. Flying close when when lead was doing acro one could see
the wing tip vibrating as the tip vortices did their 'Karmann trail"
thing. The 110v 'thin filament' tip lights used to fail in a jiffy
until they rewired then for 28vDC 'heavy filament' bulbs.
We had an F4 at low altitude peg the G meter both ways when the tip of
the 600gal centerline came off as the pilot (Stormy FAC) dodged a SAM
coming right in from 12:00. Later a second F4 had the tip shot off his
centerline tank and the Gs piled on the same way. Turns out the blunt
nosed tank sets up severely disturbed airflow over the horizontal
stabilizers.
Both aircraft checked out okay except lots of 'bubble gum' was needed
to reseal the bottom of the internal wing tanks.
Walt BJ

"Walt BJ" wrote in message
m...
The F4 wingtips cracked from vibration, not G. However, G set up the
vibration. Flying close when when lead was doing acro one could see
the wing tip vibrating as the tip vortices did their 'Karmann trail"
thing.

More apropriatly called gain in s-plane analysis, but true.

On 19 Sep 2003 10:29:42 -0700, (Walt BJ) wrote:

The F4 wingtips cracked from vibration, not G. However, G set up the
vibration. Flying close when when lead was doing acro one could see
the wing tip vibrating as the tip vortices did their 'Karmann trail"
thing. The 110v 'thin filament' tip lights used to fail in a jiffy
until they rewired then for 28vDC 'heavy filament' bulbs.
We had an F4 at low altitude peg the G meter both ways when the tip of
the 600gal centerline came off as the pilot (Stormy FAC) dodged a SAM
coming right in from 12:00. Later a second F4 had the tip shot off his
centerline tank and the Gs piled on the same way. Turns out the blunt
nosed tank sets up severely disturbed airflow over the horizontal
stabilizers.
Both aircraft checked out okay except lots of 'bubble gum' was needed
to reseal the bottom of the internal wing tanks.
Walt BJ

Thanks Walt for explaining that. I knew they were cracked, but not the
exact why. I never got over seeing those massive plates on the outer
wing panels. Just seemed like more madness of the Vietnam war...

On Sat, 20 Sep 2003 05:08:08 GMT, Buzzer wrote:

On 19 Sep 2003 10:29:42 -0700, (Walt BJ) wrote:

The F4 wingtips cracked from vibration, not G. However, G set up the
vibration. Flying close when when lead was doing acro one could see
the wing tip vibrating as the tip vortices did their 'Karmann trail"
thing.
Walt BJ

Thanks Walt for explaining that. I knew they were cracked, but not the
exact why. I never got over seeing those massive plates on the outer
wing panels. Just seemed like more madness of the Vietnam war...


The corrective reinforcing plates, while a bit ugly weren't all that
massive--probably about 4x8 inches and maybe 1/4 inch thick. The went
in place abutting the hinges at the wing fold on both sides; main wing
and tip section. The real "ugliness" was that the paint had to be
scrapped away from the hinge and reinforcement to allow visual
inspection for cracks during preflight.

Not at all related to the "madness"--simply a fact of life that metal
can only be flexed so many times before it fatigues. We had the
reinforced wings at Torrejon while I was flogging F-4Cs from '73 to
'77. Hardly noticed them after a while.

On Sat, 20 Sep 2003 15:14:04 GMT, Ed Rasimus
wrote:

Thanks Walt for explaining that. I knew they were cracked, but not the
exact why. I never got over seeing those massive plates on the outer
wing panels. Just seemed like more madness of the Vietnam war...


The corrective reinforcing plates, while a bit ugly weren't all that
massive--probably about 4x8 inches and maybe 1/4 inch thick.

I go for 12x8 and 3/8ths, but anyway they were massive to me. I never
saw anything that big on a B-52, and it seemed completely out of place
on a little F-4. (I was out of B-52s from 1966 to 1976 so the D model
and such might have grown patches like that while I was away.)

The went
in place abutting the hinges at the wing fold on both sides; main wing
and tip section. The real "ugliness" was that the paint had to be
scrapped away from the hinge and reinforcement to allow visual
inspection for cracks during preflight.

Not at all related to the "madness"--simply a fact of life that metal
can only be flexed so many times before it fatigues. We had the
reinforced wings at Torrejon while I was flogging F-4Cs from '73 to
'77. Hardly noticed them after a while.

A fact of life that the U.S. government can't supply the people that
defend it with something more than a patched up worn out airframe?