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grover posted:Found a fantastic story looking for turbofan reliability numbers, and thought I'd share: Holy poo poo. I didn't know where the guy was going until after the launch, and then I realized that is why we spend millions of dollars to train naval aviators the way we do. What a remarkable display of capability.
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Feb 23, 2012 03:06
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Advent Horizon posted:Aren't the E-3s running used commercial 707 engines at this point? TF-33/JT3D. I don't think they're allowed to restart once they shut down in flight, at least for most of the reasons we see. I don't recall it happening on any of my flights. Edit: I was hoping you'd answer that one. I am somewhat pleased that my last 3 flights included 3 IFEs, two involving engine shutdowns. Godholio fucked around with this message at 04:11 on Feb 23, 2012 |
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Feb 23, 2012 03:35
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Advent Horizon posted:Aren't the E-3s running used commercial 707 engines at this point? No. We are operating TF-33-100A's previously slung on C-141's and B-52's minus thrust reversers and modded with embiggened generators. RE: in-flight restart. We can as long as we know why the engine shutdown or was shutdown. There are some circumstances that are, without question, going to require a previously shut down engine to be cranked up again. Those are mostly of the "OHFUCKOHFUCK" variety. bloops fucked around with this message at 03:47 on Feb 23, 2012 |
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Feb 23, 2012 03:44
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HeyEng posted:RE: in-flight restart. We can as long as we know why the engine shutdown or was shutdown. There are some circumstances that are, without question, going to require a previously shut down engine to be cranked up again. Those are mostly of the "OHFUCKOHFUCK" variety. I was referring to single engine fighters. If it goes out, I'd be attempting a restart.
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Feb 23, 2012 04:07
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Standing ovation to Nebakenezzer! What a great start to my day, two cups of coffee and a Zeppelin lecture! Well done. I went from reading about twin engine naval ops last night, via the odd 50s and 60s types to nukes. I am sure I missed some house chores, but it was fun anyway. Came across this factoid which I found quite astonishing - in an article about the Tsar Bomba, an AI favorite. http://nuclearweaponarchive.org/Russia/TsarBomba.html quote:In preparing its estimate of the bomb's yield the U.S. had data about the test that was collected surprisingly close at hand. With the advance notice of Khrushchev's announcement, and the other tests in the series, a crash program code-named Speedlight was organized at the behest of Hebert Scoville (Joint Atomic Energy Intelligence Committee chairman) and Gerald Johnson (assisstant to the Secretary of Defense for atomic energy). A KC-135 Stratotanker was modified to carry broadband electromagnetic and speical optical equipment (which would have included a high-speed photometer called a "bhangmeter"). The modification was carried out under the supervision of Doyle Northrup by an Air Force unit headquartered at Wright-Patterson AFB called "Big Safari." The plane was ready for overseas deployment to its staging base by 27 October. Crossing over the Arctic Ocean, Speedlight was able to get quite close to the detonation point; close enough that the fuselage suffered scorching (suggesting it was closer than the 45 km separation of the Tu-95 drop aircraft).  PS Bhangmeter? Really? Is a "bhang" some sort of measure of neutron flux, gamma intensity or other exotic nuclear spectacle? No. No it isn't. quote:The name of the detector is a playful pun, which was bestowed upon it by Fred Reines, one of the scientists working on the project. The name is derived from the Indian word "bhang", a locally grown variety of cannabis which is smoked or drunk to induce intoxicating effects, the joke being that one would have to be on drugs to believe the bhangmeter detectors would work properly. This is in contrast to a "bangmeter" one might associate with detection of nuclear explosions. http://en.wikipedia.org/wiki/Bhangmeter
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Feb 23, 2012 11:41
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Advent Horizon posted:I was referring to single engine fighters. If it goes out, I'd be attempting a restart. It depends why it went out. It depends what regime of flight you are in.
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Feb 23, 2012 18:19
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I'd be wary of using commercial turbofan reliability metrics to draw any conclusions about military single-engine fighters. The maintenance practices for modern turbofans are to basically keep it filled with oil until several thousand cycles or something breaks, whichever occurs first. I have no direct knowledge, but I wonder if the manuals for an F100 or F110 in an F-16 are a bit more stringent and proactive.
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Feb 23, 2012 19:42
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^^^That isn't really the case. Civilian operators have extremely stringent standards that must be achieved in terms of reliability; much higher than any military standard (if they even exist in the first place, that is). As an example, twin-engine aircraft must demonstrate an IFSD rate of better than 2 per 100,000 flying hours before they're allowed to fly with 180-minute ETOPS. In addition, airlines must also maintain their aircraft so that they maintain at least that rate throughout their service life. If they fail to do so, the regulator will pull their ETOPS certification in a heartbeat; it's one of the few things they don't mess around with.Godholio posted:Holy poo poo, really? I'd love to see what it is on military heavies using older engines, like E-3s. No loving way they'll release that info, though. In civilian service, the JT3D/TF-33 had an IFSD rate of roughly 60 per 100,000 flying hours, if my sources are correct. Now that a lot of these engines are getting on 50 years, I imagine the shutdown rate is only getting worse.
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Feb 23, 2012 21:07
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 http://www.youtube.com/watch?v=3wvEzhyY9F4&feature=g-vrec&context=G2e9838cRVAAAAAAAAAg
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Feb 23, 2012 21:13
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Perhaps I was too glib, but I was genuinely asking what the maintenance practices for single-engine fighters are while just stating that commercial turbofans were not necessarily the best basis for extrapolation. I am familiar with ETOPS, but with the engine models I deal with, the turbomachinery is so mature, the maintenance intervals are driven by crap LRUs more than anything. I know what it takes for an airline to keep its aircraft in revenue service, but what does the military do to keep its aircraft ready to sortie?
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Feb 23, 2012 21:25
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Preoptopus posted:
Impressive as an engineering achievement, but shame on the B-36 for it's role in what Convair did to the B-49. 
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Feb 23, 2012 21:27
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Preoptopus posted:
I watched this movie a million times when I was a kid. Part of it was filmed at MacDill AFB, near where I grew up. 
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Feb 24, 2012 05:31
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Understeer posted:I know what it takes for an airline to keep its aircraft in revenue service, but what does the military do to keep its aircraft ready to sortie? I'm an AF (munitions) maintenance officer, so although I don't have too much direct experience with the flightline I can shed a little light on this...broadly speaking the USAF's standards (and as far as I know the NAVAIR (Navy/USMC) standards are generally similar) are going to be just as, if not more, stringent than your average first world airline. Frequent JOAP burns (oil analysis) as well as other forms of NDI and regularly scheduled engine swaps/overhauls...the biggest problems we run into (as I'm sure Godholio and/or HeyEng can speak to) are e: I should add though that as far as ETOPS certification and poo poo like that...yeah, there's no way we would be able to meet that stringent of a standard fleet wide, given the overall age of our fleet. Certain airframes, maybe, and I would say that the fighter community probably comes closer to that standard given the relative lack of redundancy with engines, although they have fairly frequent engine swaps and overhauls and their average flight time is going to be considerably less than your average long haul flight where ETOPS comes into play. If you really have some time to kill, here's an online repository of all the AF AIB reports for Class A mishaps going back to FY2000. iyaayas01 fucked around with this message at 05:58 on Feb 24, 2012 |
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Feb 24, 2012 05:52
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Tsuru posted:Not sure if this is what he is talking about, but it is a video of an F-16 entering a spin during a dogfight. I'm not even sure if a failure of the flight control system is what is needed to get an F-16 to spin, but I'm sure someone can fill in the blanks. Not even close. That's amazingly stable, even in a spin, compared to what the plane will do when the 4 redundant flight controllers all fail.
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Feb 24, 2012 07:00
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Southwest 737-800 is here... http://www.airliners.net/photo/Southwest-Airlines/Boeing-737-8H4/2070120/L/
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Feb 24, 2012 08:15
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grover posted:Found a fantastic story looking for turbofan reliability numbers, and thought I'd share: Question, what is "cat seal" that is mentioned a few times? A seal that goes in the groove that the shuttle runs down?
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Feb 24, 2012 08:51
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ORNITHOPTERS ARE REAL, GUYS.
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Feb 24, 2012 09:58
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so ugh, I guess something went loose during landing? http://www.huffingtonpost.com/2012/02/23/brazil-helicopter-falls-apart_n_1297748.html 
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Feb 24, 2012 14:14
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Here's a page with a bunch of cool pictures of some serious low level flying...some of them have been posted before, but the entire page is well worth a look.
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Feb 24, 2012 15:05
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Kerrow posted:so ugh, I guess something went loose during landing? Looks like it went into ground resonance. Couldn't tell you why, though.
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Feb 24, 2012 15:53
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Fire Storm posted:Question, what is "cat seal" that is mentioned a few times? A seal that goes in the groove that the shuttle runs down?  This guy makes it look easy, but it's actually rather heavy and rigid enough to stand up to aircraft and equipment carts rolling over it. 
grover fucked around with this message at 16:30 on Feb 24, 2012 |
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Feb 24, 2012 16:13
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Phanatic posted:Looks like it went into ground resonance. Couldn't tell you why, though. It only happens on helicopters with articulated rotor systems, which basically means that the blade is attached in a manner that allows the blades to flap (move up and down) and lead and lag (move back and forth) individually. The lead and lag is usually controlled by some sort of damper. When ground resonance happens, it's almost always due to worn out dampers. The disruption caused by hitting the ground causes the blades to start leading and lagging out of sync, and it will continue to get worse unless the pilot lifts the helicopter back into the air and tries to land as gently as possible. It can also happen on take off, but since the helicopter is getting airborne, it doesn't turn into the mess you see in this video.
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Feb 24, 2012 19:08
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Helicopters are stupidly complex and prone to all kinds of horrible phenomenons that have cold and matter-of-fact names. Settling with power = carnage Dynamic rollover = carnage Receeding blade stall = carnage Mast bump = carnage And now I've learned about ground resonance, putting it down for carnage as well. They are an abomination before the flying gods. If Isaac Newton had lived to see his actio/reaction discovery treated like this he would cry with horror and guilt. edit: iyaayas01 posted:Here's a page with a bunch of cool pictures of some serious low level flying...some of them have been posted before, but the entire page is well worth a look. Holy hell this was good. Ola fucked around with this message at 20:47 on Feb 24, 2012 |
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Feb 24, 2012 19:28
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iyaayas01 posted:Here's a page with a bunch of cool pictures of some serious low level flying...some of them have been posted before, but the entire page is well worth a look. Best Post in the thread
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Feb 24, 2012 20:30
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TheCobraEffect posted:It only happens on helicopters with articulated rotor systems, Yes, but I've never seen it happen to one on skids instead of wheeled gear. Aside from the lag dampers, the oleo-type struts on the landing gear are usually where things go wrong. Ola posted:
Here's the mother of all ground resonance demonstrations: https://www.youtube.com/watch?v=vTRuWgoEFxo https://www.youtube.com/watch?v=D2tHA7KmRME The descriptions of the video are wrong. This wasn't a "ground resonance test," this was a damaged bird that belonged to the 160th. On a ferry flight, it experienced what you could term a severe uncommanded control response, and actually rolled completely over in flight (carnage). They got control back at something like 500' AGL, nobody got killed, but to say the airframes aren't designed with that kind of loading in mind would probably be an understatement (especially since it was an old A model that had been modded into being a D). So what to do with it? Turn it over to the guys at APG so they can use it for weapons-effect testing. They ripped the landing gear out, and chained it down rigidly to the ground. They were planning on running up the engines and shooting various guns at various locations to see what broke how. Turns out that if you rip the regular landing gear off a -47 and chain it rigidly to the ground, well, that's what happens. It's a real "Doctor, it hurts when I move my arm like this" kind of thing.
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Feb 24, 2012 20:46
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iyaayas01 posted:Here's a page with a bunch of cool pictures of some serious low level flying...some of them have been posted before, but the entire page is well worth a look. holy poo poo
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Feb 24, 2012 20:54
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Phanatic posted:Yes, but I've never seen it happen to one on skids instead of wheeled gear. Aside from the lag dampers, the oleo-type struts on the landing gear are usually where things go wrong. That's funny, I've never seen it happen to one on wheeled gear. I thought the impact from the rigid skids hitting the ground is what set it off most of the time. It does make sense that some improperly serviced or just old struts would cause issues though.
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Feb 24, 2012 21:30
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slidebite posted:holy poo poo
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Feb 24, 2012 21:32
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slidebite posted:holy poo poo another gem 
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Feb 24, 2012 22:05
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Preoptopus posted:
I still can't get over the B-36. "Let's just strap 4 jet engines to it - for science!" 
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Feb 24, 2012 22:27
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Nostalgia4Infinity posted:I still can't get over the B-36. It's more a case of "Oh poo poo. Maybe if we strap 4 jet engines to it...?"
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Feb 24, 2012 23:12
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law abiding rapist posted:another gem 
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Feb 25, 2012 01:32
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brains posted:those are both amazing but you guys are somehow ignoring this Airshows were probably so much more exciting when the planes weren't a quarter mile out from the crowd. 
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Feb 25, 2012 02:53
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Telephoto compression makes this more  than it really is:
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Feb 25, 2012 02:59
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brains posted:those are both amazing but you guys are somehow ignoring this Pretty fly for a white guy.
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Feb 25, 2012 05:36
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Ola posted:Helicopters are stupidly complex and prone to all kinds of horrible phenomenons that have cold and matter-of-fact names. Vortex ring state = carnage edit: it seems that it and Settling with power are the same thing. oops. Stormangel fucked around with this message at 09:27 on Feb 25, 2012 |
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Feb 25, 2012 09:23
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Vortex ring state sounds much more  though, you'd expect it to end in carnage.
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Feb 25, 2012 10:21
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Some Russians had a scare yesterday. http://www.bbc.co.uk/news/world-europe-17157863
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Feb 25, 2012 18:47
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Edit: ^^^^ is it just me or is that flight way, way overcrewed? 7 crew 37 pax? Captain Postal posted:It's more a case of "Oh poo poo. Maybe if we strap 4 jet engines to it...?" my favorite is that they turn them off for cruise. it was like gently caress we need to get this bad larry off the ground but we don't wanna waste gas while we're driving 9000 nmi to nuke Smolensk or whatever. I wonder do they turn them back on for landing in case they have to TOGA. I imagine trying to do that with just the six props would be horrifying.
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Feb 25, 2012 19:10
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KYOON GRIFFEY JR posted:Edit: ^^^^ is it just me or is that flight way, way overcrewed? 7 crew 37 pax? I bet they were counting stewardess's in that number too, the flight crew should only be 2, and the plane can seat 70-80 people. And who knows, maybe they counted a pilot who was catching a ferry ride or something too.
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Feb 25, 2012 19:30
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