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#11
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Chad Irby wrote:
In article , "José Herculano" wrote: Maximum I read regarding the Phantom was a guy in Vietnam pulling 14 G to get an ass-SAM divergence. The bird held and landed. I know there were a couple of cases in Vietnam where F-4s made hard enough turns to rip the ECM pods off... Gotta wonder about that, since ECM pods were routinely carried in the Sparrow missile wells. Can't imagine a situation in which the pods suspension gear would fail. Don't say it couldn't, simply that I doubt it. In 250 combat missions, 150 over NVN where high threat evasions were most likely, I never, not even once, heard of a structural failure nor of an inadvertent separation of any piece of equipment off an aircraft. I'm not saying it couldn't have, simply that I doubt it. YMMV. Ed Rasimus Fighter Pilot (ret) ***"When Thunder Rolled: *** An F-105 Pilot Over N. Vietnam" *** from Smithsonian Books ISBN: 1588341038 |
#12
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"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... |
#13
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"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 :-) |
#14
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In article ,
Ed Rasimus wrote: Chad Irby wrote: I know there were a couple of cases in Vietnam where F-4s made hard enough turns to rip the ECM pods off... Gotta wonder about that, since ECM pods were routinely carried in the Sparrow missile wells. Can't imagine a situation in which the pods suspension gear would fail. Don't say it couldn't, simply that I doubt it. The missile well adapter was only held on by four moderate-sized bolts, and I could see quite a few situations where the whole assembly would pull right out. I had to swap the MWAs out on a regular basis when I was at George AFB. They kept launchers in that left-front spot until the regs forced to exercise with the pods. I also seem to remember at least one case where one of the hooks on an MWA cracked, and the pod came back in being held by the rear lug only... In 250 combat missions, 150 over NVN where high threat evasions were most likely, I never, not even once, heard of a structural failure nor of an inadvertent separation of any piece of equipment off an aircraft. I'm not saying it couldn't have, simply that I doubt it. Even when the thing was in good shape, I could see one or more bolts giving way under a hard maneuver, taking the rest of them out too. -- Remember: Objects in rearview mirror may be hallucinations. Slam on brakes accordingly. |
#15
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"Peter Kemp" peter_n_kempathotmaildotcom wrote in message
On Thu, 18 Sep 2003 19:03:03 +0100, "José Herculano" wrote: An Argentinian 707 shadowing the British fleet pulled 7 G to avoid a couple of Sea Dart missiles. She too landed. The second claim is incorrect. No Sea Dart missiles were ever launched at the shadowing aircraft. by a British vessel, although at one point they nearly did, before identifying the aircraft as (IIRC) a Brazilian charter flight. No, it's correct. It is true that the British never fired on the 707s that shadowed the main Task Force on its trip south, and those flights ended for several weeks after a pointed warning. However, the Argentines did eventually resume the flights, conducting reconnaissance against British reinforcements headed south from Ascension. On 22 May, HMS Bristol and HMS Cardiff each fired a pair of Sea Darts at a 707 belonging to Grupo 1, which took evasive action as desribed above. Source: _Falklands: The Air War_ -- Tom Schoene Replace "invalid" with "net" to e-mail "If brave men and women never died, there would be nothing special about bravery." -- Andy Rooney (attributed) |
#16
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Ed Rasimus wrote:
Chad Irby wrote: I know there were a couple of cases in Vietnam where F-4s made hard enough turns to rip the ECM pods off... Gotta wonder about that, since ECM pods were routinely carried in the Sparrow missile wells. Can't imagine a situation in which the pods suspension gear would fail. Don't say it couldn't, simply that I doubt it. In 250 combat missions, 150 over NVN where high threat evasions were most likely, I never, not even once, heard of a structural failure nor of an inadvertent separation of any piece of equipment off an aircraft. I'm not saying it couldn't have, simply that I doubt it. I doubt it too! I don't know how much an F-4 ECM pod weighs, but I do know that it would require a hellacious amount of G's to cause the bolts that fasten the pod to the airframe to fail. Much more force than the surrounding airframe structure itself could withstand. For example, a standard AN6 bolt (3/8-inch diameter shank) has a shear strength of approx. 8700 lbs. IIRC. And there is probably more than just one of these or similiar types of bolts securing the ECM gear to the belly of an F-4. -Mike (A&P mech) Marron |
#17
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"Mike Marron" wrote in message ... Ed Rasimus wrote: Chad Irby wrote: I know there were a couple of cases in Vietnam where F-4s made hard enough turns to rip the ECM pods off... Gotta wonder about that, since ECM pods were routinely carried in the Sparrow missile wells. Can't imagine a situation in which the pods suspension gear would fail. Don't say it couldn't, simply that I doubt it. In 250 combat missions, 150 over NVN where high threat evasions were most likely, I never, not even once, heard of a structural failure nor of an inadvertent separation of any piece of equipment off an aircraft. I'm not saying it couldn't have, simply that I doubt it. I doubt it too! I don't know how much an F-4 ECM pod weighs, but I do know that it would require a hellacious amount of G's to cause the bolts that fasten the pod to the airframe to fail. How could you possibly know that? |
#18
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Mike Marron wrote:
Chad Irby wrote: I know there were a couple of cases in Vietnam where F-4s made hard enough turns to rip the ECM pods off... I don't know how much an F-4 ECM pod weighs, but I do know that it would require a hellacious amount of G's to cause the bolts that fasten the pod to the airframe to fail. Much more force than the surrounding airframe structure itself could withstand. For example, a standard AN6 bolt (3/8-inch diameter shank) has a shear strength of approx. 8700 lbs. IIRC. And there is probably more than just one of these or similiar types of bolts securing the ECM gear to the belly of an F-4. The only problem is that the missile well adapter isn't held in by the full strength of 4 brand-new bolts... it's held in by the bolt *threads*. You're not working with the shear strength of a 3/8" diameter piece of metal - you're dealing with the actual (not theoretical) tensile strength of the *threads* of that bolt *and* the nut plate. Yep - the four bolts run straight up into the fuselage, making all of the stress rest on the four bolts, through their four nut plates. That shouldn't be a problem, since correct installation would give you full strength. Except... That's the problem with thoretical and design limits. After a few months of actual (mis)use, those numbers change. A *lot*. The spec says that someone should replace those nut plates and bolts each time you swap out the launcher for the MWA. Nobody did that, of course. Took too long, cost too much. Sure, the four bolts, when new, should have been able to hold a total of almost 35,000 pounds. But then you add in the preload from torquing it in (at least 600 pounds per bolt, maybe more) plus the 6000 pounds it would have been carrying with a 600 pound pod at ten times the force of gravity (maybe higher), and you have a load of at least 8400 pounds, on a system that is not evenly loaded, in six kinds of vibration modes, loading and unloading like mad. I figure one semi-catastrophic failure over a quarter century is pretty good, considering. -- Remember: Objects in rearview mirror may be hallucinations. Slam on brakes accordingly. |
#19
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On Thu, 18 Sep 2003 16:45:14 -0700, "Tarver Engineering"
wrote: "Mike Marron" wrote in message .. . Ed Rasimus wrote: Chad Irby wrote: I know there were a couple of cases in Vietnam where F-4s made hard enough turns to rip the ECM pods off... Gotta wonder about that, since ECM pods were routinely carried in the Sparrow missile wells. Can't imagine a situation in which the pods suspension gear would fail. Don't say it couldn't, simply that I doubt it. In 250 combat missions, 150 over NVN where high threat evasions were most likely, I never, not even once, heard of a structural failure nor of an inadvertent separation of any piece of equipment off an aircraft. I'm not saying it couldn't have, simply that I doubt it. I doubt it too! I don't know how much an F-4 ECM pod weighs, but I do know that it would require a hellacious amount of G's to cause the bolts that fasten the pod to the airframe to fail. How could you possibly know that? Math. |
#20
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In article ,
Scott Ferrin wrote: On Thu, 18 Sep 2003 16:45:14 -0700, "Tarver Engineering" wrote: "Mike Marron" wrote in message .. . I don't know how much an F-4 ECM pod weighs, but I do know that it would require a hellacious amount of G's to cause the bolts that fasten the pod to the airframe to fail. How could you possibly know that? Math. ....and a near-religious faith that new bolts are just as strong as old bolts, while corrosion never happens and flightline troops never make mistakes. Film at 11. -- Remember: Objects in rearview mirror may be hallucinations. Slam on brakes accordingly. |
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