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

"Gord Beaman" ) wrote:
Mike Marron wrote:

My point is simply that as any competent mechanic knows, it is a bad
practice to put shear loads in the threaded area of a bolt. Were these
all-thread bolts and what type of loads were they designed for? It's
still difficult to believe that a pilot could put enough G on the
airplane to cause the ECM pod to depart the airframe.

Marron, for Christ's sake, what are you talking about??...'shear'
loads are "ACROSS THE BOLT". These bolts are installed so that
they will fail (when they do) by stripping the threads or
breaking the bolt "by STRETCHING it till the shank or the threads
fail".

A 'shear failure' will happen when a bolt is SHEARED off at ~90
degrees to the shank.

Why do you suppose it's called shear strength? and why do you
suppose shear strength is so much higher than tensile
strength?...god...

You really are a hysterical old priss aren't you Gord? Jumping up
and down and pounding your white-knuckled fists in frustration
about sheer loads, of all things. Christ, why don't you just go find
a cute little dimpled, hexhead bolt to fellate. It would be less
pathetic, at least philosophically.

Let me clue you in to the obvious Gord, nobody gives half of a
dead rat's scrotum if the bolts failed in tension or in shear. The
point is that, according to at least one former U.S. Air Force
mechanic, they indeed failed. Catastrophically. In combat. Now
Gord, you've put a nice little rant together, but then again, so has
the tarv troll whom I am happily ignoring while he too follows me
around the NG like a puppy dog.

But at your age Gord, you really shouldn't get so worked up about
these things. I realize that you have nothing better to do than to
sit at your beloved 'puter up there in the great frozen north with
your anal duct puckered up in anticipation of another one of your
nit-noid, boring arguments-for-the-sake-of-arguing. However,
I suggest you loosen it a bit, because the freight train of
irrelevance is about to take the express track up your ass.

In any event, I'm so glad you have become such an overnight,
"instant expert" on how bolts are designed to fail. My A&P school
and professional wrenching days was many moons ago and one
of the reasons I stop in here so frequently is to learn about these
things from contrary, sackless douchebags like you. Don't get me
wrong, I still don't quite understand how F-4 ECM pods have been
known to tear apart from the airframe in combat, but then, I also
don't understand why you think I'd be interested in your useless
critiques of my replies.

On Sat, 20 Sep 2003 20:10:07 GMT, Chad Irby
wrote:

In article ,
Mike Marron wrote:

But once again, doubtful the "brainy" types in St. Louis designed the
ECM pod fasteners to take shear loads in the threaded area
anyway (it is a bad practice to do this with any bolt, AN or
otherwise).

You can "doubt" all you want, but that's not how the damned things were
put together.

Thinking about bolts shearing I wonder if it could have been like
pylon sway brace bolts that would get worn. No visible damage to the
threads, but when you went to torque them down they wouldn't be tight
against the pod. With a pod because of the length you could shake them
and get a feel for a loose sway brace bolt. Maybe 3 bolts torqued up
tight to the plate and one a hair away from the plate would decrease
the load carrying ability enough to have a pod come off?

Wasn't something said about mechanics carrying bolts around?
I remember now we use to carry spare sway brace bolts and nuts in our
truck.

Buzzer wrote:

Thinking about bolts shearing I wonder if it could have been like
pylon sway brace bolts that would get worn. No visible damage to the
threads, but when you went to torque them down they wouldn't be tight
against the pod. With a pod because of the length you could shake them
and get a feel for a loose sway brace bolt. Maybe 3 bolts torqued up
tight to the plate and one a hair away from the plate would decrease
the load carrying ability enough to have a pod come off?

That could be something of a factor, but the sway brace bolts were a lot
bigger than the bolts holding the MWA to the airframe, and we were very
careful about getting them tight. Multiple inspections, et cetera.

Wasn't something said about mechanics carrying bolts around?
I remember now we use to carry spare sway brace bolts and nuts in our
truck.

We usually inspected the MWAs off of the plane, and replaced the bolts
back at the shop when necessary. Considering the size and external
placement of the sway braces, it was very easy to do a good visual
inspection before we put the pod on.

--
cirby at cfl.rr.com

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

Nothing to contribute, except for glorification of self?



"Tarver Engineering" wrote

It is difficult to understand how FAA could continue to allow Marron to hold
and A&P certificate, in light of his obvious incompetence; in his delegated
area of expertise.

Chad Irby wrote:
Mike Marron wrote:

But according to you, that's how the damned things came apart. Yea or
nay?

What I'm saying is that the Missile Well Adapter for electronic warfare
pods for the F-4 Phantom was held onto the plane by four bolts running
straight up into the airframe.

You claimed that was "doubtful."

You were (and are still) 100% wrong.

Oops! Instead of answering the question now you're dodging the
question and putting words in my mouth.

I doubted that A) the ECM pod ripped apart from the airframe as you
said, and 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."

Now, pardon me if I missed something but I respectfully ask you
once again (for my own edification) in your opinion -- was it the
bolts, the design itself or what was the culprit with regards to what
you said about the ECM gear "ripping apart" from the airframe?

Sincerely,
-Mike Marron

Buzzer wrote:

Thinking about bolts shearing I wonder if it could have been like
pylon sway brace bolts that would get worn. No visible damage to the
threads, but when you went to torque them down they wouldn't be tight
against the pod. With a pod because of the length you could shake them
and get a feel for a loose sway brace bolt. Maybe 3 bolts torqued up
tight to the plate and one a hair away from the plate would decrease
the load carrying ability enough to have a pod come off?

I remain unconvinced that the ECM pod ripped off as the result
of over-G's like Chad said because any G force powerful enough
to cause AN hardware to fail catastrophically like that would most
likely result in some of the surrounding airframe structure to fail
along with it. But as the old adage goes, **** happens. Perhaps the
bolts were over-torqued and were stretched beyond limits, elongation
of the plate(s), or WTF?

Wasn't something said about mechanics carrying bolts around?
I remember now we use to carry spare sway brace bolts and nuts in our
truck.

In addition to a small assortment of tools, I sometimes carry around
a few spare pip pins, tie-down rings, tie-wraps, rubber O-rings, and
of course, bungee cords in my A/C. On the first plane I built, I found
that 032" safety wire comes in handy from time to time not just to
help secure things, but also to unplug the carb main jets in the
field.

-Mike Marron

In article ,
Mike Marron wrote:

Oops! Instead of answering the question now you're dodging the
question and putting words in my mouth.

Nope. The questions have been answered about three differenet ways, you
just don't seem to understand the answers.

As far as putting words in your mouth...

I doubted that A) the ECM pod ripped apart from the airframe as you
said,

....and *all* of the reasons you gave for that doubt were based on some
very bad assumptions... which I covered. Multiple times.

and B) the pod fasteners were designed to take shear loads in
the threaded area.

....which is completely wrong. You haven't seen the part of the plane in
question, and you're well, just flat-out wrong. There's no other way to
put it. It's four bolts, run straight into the bottom of the plane.

Period.

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

See your comment B) above, which contradicts this.

Now, pardon me if I missed something but I respectfully ask you
once again (for my own edification) in your opinion -- was it the
bolts, the design itself or what was the culprit with regards to what
you said about the ECM gear "ripping apart" from the airframe?

As I've said a couple of times, it could have been a number of things,
including the design, wear, corrosion, and G-force.

--
cirby at cfl.rr.com

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

In article ,
Mike Marron wrote:

I remain unconvinced that the ECM pod ripped off as the result
of over-G's like Chad said

....except I never claimed just that.

because any G force powerful enough to cause AN hardware to fail
catastrophically like that would most likely result in some of the
surrounding airframe structure to fail along with it.

Bad assumption, in that you think all airframes are always new, always
perfectly maintained, and perfectly designed.

But as the old adage goes, **** happens. Perhaps the bolts were
over-torqued and were stretched beyond limits, elongation of the
plate(s), or WTF?

Oh, *now* you start to get it. Took you long enough.

--
cirby at cfl.rr.com

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

Chad Irby wrote:
Mike Marron wrote:

Oops! Instead of answering the question now you're dodging the
question and putting words in my mouth.

Nope. The questions have been answered about three differenet ways, you
just don't seem to understand the answers.

There ya' go again dodging questions. Look, we're both adults and
mechanics here but I'm rapidly giving up hope trying to have any
semblance of a meaningful dialogue with you. But I'll give it one more
shot and see what happens. Once again, were these "four bolts" that
you keep referring to all-thread bolts and what type of loads were
they designed for?

As far as putting words in your mouth...

I doubted that A) the ECM pod ripped apart from the airframe as you
said,

...and *all* of the reasons you gave for that doubt were based on some
very bad assumptions... which I covered. Multiple times.

Excuse me? Assuming that it would require a hellacious amount of G's
to cause the bolts that fasten the ECM pod to the airframe to fail is
a "bad" assumption? Assuming that the surrounding airframe structure
might be also be effected in the event of such a catastrophic failure
occurring is a "bad" assumption? And assuming that the McDonnell
Douglas engineers aren't stupid and would not design the ECM pod
fasteners to take shear loads in the threaded area of a fastener is a
"bad" assumption?

and B) the pod fasteners were designed to take shear loads in
the threaded area.

...which is completely wrong. You haven't seen the part of the plane in
question, and you're well, just flat-out wrong. There's no other way to
put it. It's four bolts, run straight into the bottom of the plane.

There ya go again fixating on them "four bolts." Allow me to explain
one more time that I doubt that the fasteners were designed to take
shear loads in the threaded area NOT that there were "four bolts
running straight into the bottom of the plane." I don't care if there
were Forty fuggen bolts running straight through the TOP of the plane,
my doubt comes from your implication that the pod fasterners were
designed to take shear and/or tension loads in the THREADED AREA
of the bolts. Comprende, amigo?

Now, pardon me if I missed something but I respectfully ask you
once again (for my own edification) in your opinion -- was it the
bolts, the design itself or what was the culprit with regards to what
you said about the ECM gear "ripping apart" from the airframe?

As I've said a couple of times, it could have been a number of things,
including the design, wear, corrosion, and G-force.

Anytime something falls off ANY airplane, be it an ECM pod falling
from an F-4 or an engine falling from a DC-10, this is bound to raise
a few eyebrows. In the interest of safety not only for the aircrew
and/or passengers, but the public at large down on the ground, it
would be kinda' nice to know EXACTLY what caused such things
to occur.

In addition to your original comment stating that you KNOW there were
a couple cases in Vietnam where F-4's made hard enough turns to rip
the ECM pods off, you also said that F-4 pilots who were risking their
butts in the deadly skies over 'Nam didn't like ECM pods at all
because they considered them not "manly enough or something."

GMAFB!

It shouldn't surprise you one iota that particular insulting comment
of yours raised a few more eyebrows -- this time from several former
distinguished F-4 jocks right here in this happy NG assembled.

Now, after you wrote all these somewhat inflammatory things, Chad,
whose credibility do you s'pose is at stake here? Yours, or those of
us who are doubting the incredible, somewhat inflammatory things you
write?

Think about it.

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

Chad Irby wrote:
Mike Marron wrote:

But as the old adage goes, **** happens. Perhaps the bolts were
over-torqued and were stretched beyond limits, elongation of the
plate(s), or WTF?

Oh, *now* you start to get it. Took you long enough.

I got it from the beginning. That doesn't mean I bought it then, nor
do I buy it now.

-Mike Marron