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

Juvat wrote:

Chad Irby posted:

"Getting tested on it" and "caring" are, as any high school kid can tell
you, two very different things.

Come on chad, we've gone from "severe lack of interest" to "caring?"

"Severe lack of interest" and "not caring" are pretty much the same
thing.

If I'm NOT getting tested, asked questions during
certification/verification briefings, mission qualification training,
and plain ol' ordinary day-to-day simulated "Fence" checks on a
flight...I guess you're right.

That's my point.

But I'd feel kinda silly as a pilot
saying I "cared." Alan Alda might say he "cared" but I wouldn't. I had
to know about certain aspects of EC...as a guy in the FRONT seat I
couldn't operate the ALR-46 or the ALQ-119/131.

Well, you *could* operate the ALR-46 and the ALE-40, at least partially.

As an IP, I could when
in the pit...at that point you would say I "cared."

But that's *you*. An *instructor pilot* who was expected to make sure
of that sort of thing. A lot of guys in the seat were on the verge of
hostile...

As an example, I was one of those guys who had to do end of runway
checks on the ALR-46, by talking to the back seater on the headset while
two other troops walked up the sides of the plane carrying test
transmitters. About half of the time, I'd hear the BIT tones running as
I plugged in the headset (oops - caught 'em), and it was often like
pulling teeth to get answers out of the back seat.

Exactly. If you don't use it, you don't care.

Clearly that is the only conclusion you are able to draw. Others would
disagree.

Yep. And one of them is an IP. Fancy that. I wonder if an aviator
might be a bit less forthcoming about his attitudes with an IP than with
an airman who can't do much about it?

And the way many officers dealt with it was... blow it off. If it's not
important, why care?

Again...negative training, that runs counter to "train like you
fight." C'est vrai?

Exactly. Again.

Try being the guy who has to load it on the plane and then figure out
what was "wrong" with it when it comes back with a writeup that
describes, basically, normal operation.

Life isn't fair. But it would be fair to say that the guys making
those write-ups were not PILOTs...correct?

Oddly enough, we got a lot of front-seater writeups for ECM. Those
usually came down to switchology.

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.

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

On Mon, 22 Sep 2003 17:00:18 GMT, Juvat
wrote:

Buzzer posted:

B-52 crews in the states trained as they would fight, but
fighter crews that were much closer to the "enemy" trained with one
hand tied behind their back?

WRT to turning the ALQ-119/131 on when you carried a war pod? Sure.
But in USAFE we routinely practiced/exercised all aspects of EC.

We got our Mode IV checked at EOR, getting a thumbs up or down from
the checking us. Did this in TAC and PACAF too.

We routinely did fence checks, ALR-46 in "Training" file rather than
"Open" or "Priority." Everybody...everybody knew what a ZSU-23/4
symbology looked like on the RWR. I remember what the F-16 radar
warning sounds like versus an F-4 radar. I knew that the "batwing" was
a high band threat and the "airplane" was medium band, and which
etched ring the four dots should be on...

Continuing with our everyday fence check...simulate the Pod in "Xmit 2
with xx buttons depressed." During NATO/USAFE or local exercises we
used certain local routes to simulate the Mike Plan (min risk ATC
procedures), and we used actual min risk recovery procedures. We got a
"mickey" from the Command Post after engine start to program the Have
Quick radios and checked them in secure mode but didn't use that
feature inflight since ATC and GCI weren't on the net.

And finally, Wings included pages to their aircrew weapon's guide (AKA
Ladies' Aid) that specifically covered unclassified ALR-46 and ALQ-119
operations, testing, and fault remedies. And this was for normal
day-to-day ops.

The only thing missing was carrying ECM pods routinely, and the lack
of EW ranges to practice. Once in a great while we could practice with
training pods on the Ramstein RBS or the Spade Adam range in the UK.

Did they have sims at different bases so you could at least practice
everything all together? They have cargo plane sims.

I guess what really bothers me how did they figure the OR rate for a
pod that was never used? Do the new know it all do it all pods have a
sensor that could tell if the final amp was bad if it was never turned
on?

Mike Marron wrote:
I doubted that ... B) the pod fasteners were designed to take
shear loads in the threaded area.

I did not "doubt" what you said about them "four bolts running
straight up into the airframe."

FYI, Mike, shear loads are 90 degrees to the long axis of the bolt.
Loads aligned with the long axis of the bolt are tensile loads.


Jeff

"Jeff Crowell" wrote:

FYI, Mike, shear loads are 90 degrees to the long axis of the bolt.
Loads aligned with the long axis of the bolt are tensile loads.

The A-frame downtubes on my particular A/C are loaded in
compression. The nose-strut is loaded in tension during flight,
compression on the ground. And your point is?

-Mike Marron

Ed Rasimus wrote in message . ..
On Sat, 20 Sep 2003 20:06:35 GMT, Buzzer wrote:

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

SNIP:
The C with it's wing fold hinge patches was a long way from "worn out"
and the patches weren't atypical regarding fixes for a lot of various
types and models of aircraft.

When tactical aircraft cost multiple millions apiece and when the
taxpayers deserve to get the maximum bang for their bucks and when the
Congress is reluctant to approve lots of new spending, it isn't really
a bad decision.
SNIP:

I agree, Ed, except the wheels that be could react a little quicker
when the birds are getting worn out. I was in the USAF when the F86Fs,
F100s, F105s, F4s and KB29s/KB50s/B47s/A26s all were 'retired' when
they started coming apart in the air. That cost us some good pilots.
The B52s and C130s got some heavy reskinning and doublers added to
prolong their lives.
I lost a good friend at Homestead in about 76 when the outer wing came
off during a max performance reversal - a 135* slice at .9M and and
7G- they were nose down and partially inverted and never got out of it
as the bird went into Marco Bay.
When I was working with the DC Guard out of the 31st TFW at Homestead
they were towing a 105 out of the hangar after an engine change. It
was going to be prepped for the required test hop - and a main wing
spar broke during the tow! That was it for their 105s - the previous
summer camp they lost a plane and a pilot when the spar broke during
the pitch-out for landing. Take any machine too many times to the well
and she will, some time, break on you. That, of course, goes for cars
too . . .
Walt BJ

In article , "Jeff Crowell"
wrote:

Mike Marron wrote:
I doubted that ... B) the pod fasteners were designed to take
shear loads in the threaded area.

I did not "doubt" what you said about them "four bolts running
straight up into the airframe."

FYI, Mike, shear loads are 90 degrees to the long axis of the bolt.
Loads aligned with the long axis of the bolt are tensile loads.

I read that whole convoluted thread with amusement earlier this
week when I returned from travel. So much figurative arm waving...

As a long time mechanical engineer, let me point out a few things
I saw when reading the whole distended session:
1] someone (MIke?) was absolutely correct when he said that bolts
should never be loaded in shear across the threads. There are
special bolts with unthreaded shanks for shear loading.
2]someone said bolts are roll threaded to increase strength, that
is incorrect. the reason roll threading is used is that it does not
create as bad a stress point as cut threads. Cutting threads cuts
across grain flow and roll threading pushes the grain around the
thread. No increases in strength, but less of a decrease.
3] It is perfectly reasonable that 4 bolts going straight up into the
airframe take the entire loads of a pod. Pod mounting points are
primarily loaded in bending with only a little shear. This is overcome
with tensile strength, not shear strength.
4] any good designer can transfer pod flight loads into the airframe
anyway, without putting the entire load through fasteners
5] cadmium is plated onto fasteners to prevent galvanic corrosion
with aluminum in the airframe
6] pre-loading the bolts puts the structure in compression.
Subsequent flight loads unload the compression before the
structure goes in tension. All this depends on the load paths.
7] I have some experience with "little hooks" and different alloys
and different heat treatments. Size doesn't necessarily matter.

ciao

--
Harry Andreas
Engineering raconteur

Jeff Crowell wrote:
FYI, Mike, shear loads are 90 degrees to the long axis of the bolt.
Loads aligned with the long axis of the bolt are tensile loads.

Mike Marron
The A-frame downtubes on my particular A/C are loaded in
compression. The nose-strut is loaded in tension during flight,
compression on the ground. And your point is?

My point is, you've been yapping repeatedly about not loading
bolts in shear across the threads (true, as far as it goes), when
people have repeatedly been telling you that the bolts in
question are oriented vertically "up" into the airframe and
therefore are loaded in tension, not shear.

Pardon me if you knew this--if so, why do you keep bringing
up something that does not apply to the question?


Jeff

Jeff Crowell wrote:

[blah blah]

Pardon me if you knew this

OK, ewe be excused.

-if so, why do you keep bringing up something that does not apply
to the question?

Er um, I moved on -- YOU keep bringing up something that doesn't
support Chad's contention (i.e: F-4s ripping ECM pods off).

-Mike Marron

(Harry Andreas) wrote:

I read that whole convoluted thread with amusement earlier this
week when I returned from travel. So much figurative arm waving...

As a long time mechanical engineer, let me point out a few things
I saw when reading the whole distended session:
1] someone (MIke?) was absolutely correct when he said that bolts
should never be loaded in shear across the threads. There are
special bolts with unthreaded shanks for shear loading.
2]someone said bolts are roll threaded to increase strength, that
is incorrect. the reason roll threading is used is that it does not
create as bad a stress point as cut threads. Cutting threads cuts
across grain flow and roll threading pushes the grain around the
thread. No increases in strength, but less of a decrease.
3] It is perfectly reasonable that 4 bolts going straight up into the
airframe take the entire loads of a pod. Pod mounting points are
primarily loaded in bending with only a little shear. This is overcome
with tensile strength, not shear strength.
4] any good designer can transfer pod flight loads into the airframe
anyway, without putting the entire load through fasteners
5] cadmium is plated onto fasteners to prevent galvanic corrosion
with aluminum in the airframe
6] pre-loading the bolts puts the structure in compression.
Subsequent flight loads unload the compression before the
structure goes in tension. All this depends on the load paths.
7] I have some experience with "little hooks" and different alloys
and different heat treatments. Size doesn't necessarily matter.

ciao

I was hoping a mechanical engineer type would speak up.
Now getting back to the "nuts & bolts" (pun intended) part of the
issue at hand here, please explain why or why not you think that
an F-4 could pull enough G so as to rip the ECM pod off the belly?

Thanks!

-Mike Marron
CFII, A&P, UFI (fixed-wing, weightshift, land & sea)