Aethon

Blue Origin Thread (merged)

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5 hours ago, StrandedonEarth said:

swiss_cheese.jpg

When all the holes line up, there'll be pieces to pick up.

I so need that poster at my desk.

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3 minutes ago, pincushionman said:

I so need that poster at my desk.

If you google image search for "Swiss Cheese Model" there'll be examples for pretty much every industry. I had to scroll awhile to find that generic one, so you can probably find one more specific to your industry, which is...?

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9 minutes ago, StrandedonEarth said:

If you google image search for "Swiss Cheese Model" there'll be examples for pretty much every industry. I had to scroll awhile to find that generic one, so you can probably find one more specific to your industry, which is...?

Aircraft production, specifically engine nacelles. So the quote @wumpus posted is pretty close to home too.

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1 hour ago, StrandedonEarth said:

If you google image search for "Swiss Cheese Model" there'll be examples for pretty much every industry. I had to scroll awhile to find that generic one, so you can probably find one more specific to your industry, which is...?

Yes, any industry where fails is catastrophic or even expensive or give long downtime. 
Oil industry has all of this aspects, its an bit of an joke that managers or engineers from the oil industry is poophole about safety. Guess the nuclear guys are worse. 

The Swiss cheese is used other places too, shooting ranges is an good example, don't load the gun until in position, make it visible that its not loaded by pulling back the bolt or remove the magazine and still treat it as its loaded. 
 

9 hours ago, pincushionman said:

You'd be surprised how much information can be gleaned from a seemingly-random collection of burnt, bent, and broken parts, when coupled with an intimate knowledge of how the system is supposed to work and how the event actually unfolded. It really helps if that collection of parts is nearly the complete system.

The NTSB does this all the time with airplanes. And it's almost never single-failure anymore, it's always disaster dominoes.

Yes, the exploded rocket is much like an crashed aircraft. 
The previous accident is a bit worse, exploding in supersonic speed in stratosphere over water, you will not find much.  

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I wouldn't want to be the guy who's little mistake killed Zuckenburg's plan of global domination.

Such a person may be able to hide behind his own evil mastermind, but... it's facebook. They know EVERYTHING about you.

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2 hours ago, Rakaydos said:

 but... it's facebook. They know EVERYTHING about you.

Only if you let them...

 

 

:blush:

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8 hours ago, wumpus said:

I swiped this description of a "safe" turbine failure/explosion from a bit of social media:

"Basically, engine designed not to fail. If fails, casing is supposed to contain the bits, if casing fails, fairing is designed to slow down the exploding bits enough to save plain, if fairing fails, bits should be of small enough size and velocity as to cause little to no damage. If that fails, there are no windows or seats in the likely zone of explody bits coming into plane. (Notice the window that is not there, parallel to the N1 rotor)
Basically 4 of 5 systems failed, but in whole, they all died protecting the plane as they are designed to die doing."

Don't know where you got that, but if it's in reference to a commercial airplane then a gap in the windows has nothing to do with uncontained engine failures. When you are looking at a commercial airplane and you see places where there appears to be a window missing, that's because the cabin air riser duct goes through there.

Edited by mikegarrison

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5 hours ago, Rakaydos said:

I wouldn't want to be the guy who's little mistake killed Zuckenburg's plan of global domination.

Such a person may be able to hide behind his own evil mastermind, but... it's facebook. They know EVERYTHING about you.

The satellite did not belong to Facebook, even if the mass media loves to make it sound like it did. :P They merely intended to pay rent for a small subset of the satellite's transponder capacity.

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4 hours ago, mikegarrison said:

Don't know where you got that, but if it's in reference to a commercial airplane then a gap in the windows has nothing to do with uncontained engine failures. When you are looking at a commercial airplane and you see places where there appears to be a window missing, that's because the cabin air riser duct goes through there.

Wouldn't it make sense then to place that duct where the engine pieces are likely to hit? (if it actually improved the plane's and/or peoples' likelihood of surviving)

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It would, but if you look at actual aircraft you don't see such protection. The 747 has a gap almost in line with the outboard engines, but not the inboard ones which post a greater risk. The 787 has no gap at all, the A380 has no gap. It might be a thing in older designs, the 727 has its engine mounted just aft of the last row of seats, but that might be coincidence. 

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I was recently on a 757, and I was perfectly positioned to get a facefull of debris should anything happen to the engine rotor.

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19 hours ago, Lukaszenko said:

Wouldn't it make sense then to place that duct where the engine pieces are likely to hit? (if it actually improved the plane's and/or peoples' likelihood of surviving)

No. It's not like a riser duct could stop much anyway. They are placed where they are placed for the convenience of the ECS plumbing.

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17 hours ago, andrewas said:

It would, but if you look at actual aircraft you don't see such protection. The 747 has a gap almost in line with the outboard engines, but not the inboard ones which post a greater risk. The 787 has no gap at all, the A380 has no gap. It might be a thing in older designs, the 727 has its engine mounted just aft of the last row of seats, but that might be coincidence. 

british-airways-airbus-a380-984x500.jpg

Looks like there are plenty of gaps in the window belts. I don't know why you imagine that there are not. Of course, some of those may be blanked off by the airline.

(To be clear, I don't know where the A380 runs its riser ducts. They may not go up the outside at all. Or maybe they find space to squeeze them in between the windows. But they have to go up somewhere.)

Edited by mikegarrison

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Guys, if you try to find out whether the seating is somehow correlated with the engine position in order to protect the passengers from freelance engine parts then the answer is no. Different companies/versions have different seating. And passenger's are seated overlapping when projected from the side.

Instead engines are constructed in a way that blades or parts from the fan or compressor are contained within the nacelle when the engine is destroyed.

 

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19 minutes ago, Green Baron said:

Guys, if you try to find out whether the seating is somehow correlated with the engine position in order to protect the passengers from freelance engine parts then the answer is no. Different companies/versions have different seating. And passenger's are seated overlapping when projected from the side.

Instead engines are constructed in a way that blades or parts from the fan or compressor are contained within the nacelle when the engine is destroyed.

 

Okay, so I had to dig down into this issue. The topic originated from this post:

On 05/09/2016 at 0:14 AM, wumpus said:

I swiped this description of a "safe" turbine failure/explosion from a bit of social media:

"Basically, engine designed not to fail. If fails, casing is supposed to contain the bits, if casing fails, fairing is designed to slow down the exploding bits enough to save plain, if fairing fails, bits should be of small enough size and velocity as to cause little to no damage. If that fails, there are no windows or seats in the likely zone of explody bits coming into plane. (Notice the window that is not there, parallel to the N1 rotor)
Basically 4 of 5 systems failed, but in whole, they all died protecting the plane as they are designed to die doing."

4/5 bits of swiss cheese were penetrated, and the pilot had to earn his pay landing with only one engine (and a presumably wildly imbalanced plane.  I seem to remember Rutan designed the Boomerang for a reason).  But no injuries, and after the last "slice of cheese" succeeded, no real danger.

So I had to find that "bit of social media." I searched for the closing sentence of that quote, and google hit it right away. It was written by one Shadow Blasko at fark.com ( http://www.fark.com/comments/9273681/Look-at-picture-of-this-Southwest-Air-plane-to-see-what-it-calls-a-mechanical-issue-Tag-is-for-pilot-crew ). But how true is that? Another google search (southwest airline accident engine blow up) and again the relevant hit is the first. ( http://www.independent.co.uk/news/world/americas/southwest-airlines-us-plane-emergency-landing-engine-rips-apart-new-orleans-orlando-a7213746.html )

So, what really happened?

Quote

A mechanic said the engine itself was actually intact, but the planes inlet cowl had been completely ripped away 

"Most likely something structural let loose and the entire inlet ripped off," he said. 

Photos on those articles do show an impact at the gap between the windows. But the quote above and the visibly fine spinner and fan disc in the photos contradict the idea that it was a hit from a fan or compressor piece. In fact judging from the picture the gap between windows is well behind the compressor plane. The dents at the wing root are closer to that plane, and there are windows right above there. To me it looks like that for whatever reason the inlet cowling broke up, some part of it flew into the wing root, up and behind from there hitting the fuselage on its way to history. Some part of the cowling probably went through the engine, but they are made from materials that the engines can pass without exploding. Just for this reason.

Oh, and the second article mentions this having happened at around 30k feet, so we can pretty much forget about bird strike as the immediate cause. There wont be many of those that high in the sky. Of course a previous impact can have weakened the cowling and it just happened to give up at that point.

On the actual topic, no, airliners' seating is not set up to keep passengers out of the way of an exploding compressor's fragments.

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Wow. Yeah, everything mechanic can fail. Funny thing in this case: the engine itself seems to be intact. That case probably wasn't covered by certification procedures.

Glad noone was hurt.

Looking forward to the accident report.

Edit: engine failures are more frequent than one might think, a few every year worldwide, but rarely someone gets hurt. When searching for "uncontained engine failures" i found a case of 1996 where two passengers were killed by parts from a compressor. The cause was material failure after insufficient inspection/maintenance.

 

Edited by Green Baron

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7 hours ago, mikegarrison said:

 

Looks like there are plenty of gaps in the window belts. I don't know why you imagine that there are not. Of course, some of those may be blanked off by the airline.

(To be clear, I don't know where the A380 runs its riser ducts. They may not go up the outside at all. Or maybe they find space to squeeze them in between the windows. But they have to go up somewhere.)

There weren't any on the drawings I looked at. Maybe BA have a more luxurious layout rather than packing them in like sardines? Or it was just a crap drawing. Point is, seating layouts don't seem to avoid putting passengers in the plane of the turbines.

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3 hours ago, andrewas said:

There weren't any on the drawings I looked at. Maybe BA have a more luxurious layout rather than packing them in like sardines? Or it was just a crap drawing. Point is, seating layouts don't seem to avoid putting passengers in the plane of the turbines.

Yeah, I was the one who said that in the first place. I was pointing out that when you see a gap in the windows (on a 737, for example) it has nothing to do with uncontained engine failures. It's just the ECS riser duct.

I poked around on the web looking for cutout drawings, FlightGlobal-style, And I think I saw one that showed the A380 riser ducts breaking into smaller tubes that squeeze in between the windows rather than replacing one of them. But I'm not sure.

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N1  and N2 are rated at 100 maximum. This is not endurance rated but safe rated. That means that over the life of an aircraft it is expected the the turbines will warp to the point that at N1 or N2 the turbines will fail.. There are circumstances where pilots have gone over these, it does not mean that it was unsafe, but it would be for continued operation. The endurance N1 and N2 are at about 80%, but this is seldom a goal since other parts will wear out and typically over the life of a long lived commercial jet the engines will be replaced anyway for other reasons (regulation, fuel efficiency), after all a jet engine is nothing but a big kerosene burner with a huge operating cost.

i believe that N2 is coomonly experienced max during the rotation and climbout. This is when the craft is burning the most fuel. N1 is more often experience near coffins corner, this is because the air is thin the aircraft is moving fast . These are different maxima for different turbines inside the engine. The set turbines are not the same some have three shaft. I believe that N1 sets the flight celing for any given weight, not sure. 

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44 minutes ago, PB666 said:

N1  and N2 are rated at 100 maximum. This is not endurance rated but safe rated. That means that over the life of an aircraft it is expected the the turbines will warp to the point that at N1 or N2 the turbines will fail.. There are circumstances where pilots have gone over these, it does not mean that it was unsafe, but it would be for continued operation. The endurance N1 and N2 are at about 80%, but this is seldom a goal since other parts will wear out and typically over the life of a long lived commercial jet the engines will be replaced anyway for other reasons (regulation, fuel efficiency), after all a jet engine is nothing but a big kerosene burner with a huge operating cost.

i believe that N2 is coomonly experienced max during the rotation and climbout. This is when the craft is burning the most fuel. N1 is more often experience near coffins corner, this is because the air is thin the aircraft is moving fast . These are different maxima for different turbines inside the engine. The set turbines are not the same some have three shaft. I believe that N1 sets the flight celing for any given weight, not sure. 

What is your source for this claim?

Engine thrust ratings are pretty complex, but usually speaking the limiting factor is T4, the combustor exit temperature. The turbine blades and nozzles can only take so much for so long. Running the engine at max power shortens the turbine life so much that it is only done for as little time as possible, generally only during heavy weight or short-field takeoffs. Any time the pilots can take off with reduced thrust they usually will.

N1, N2, and N3 (for three-spool engines) are not the limiting factors, even though some engines use N1 as the control parameter. (Other engines use exhaust pressure ratio as the control parameter.)

Also, the "coffin corner" has nothing to do with this at all. It's about the way that the airspeed margin can shrink between buffet stall (too fast) and separation stall (too slow) when the airplane is at a high altitude.

Edited by mikegarrison

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2 minutes ago, HebaruSan said:

"SpaceX Vehicle Recovery and Reusability Thread"

Good point. Folks let's keep this thread on at least SpaceX stuff.

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While we wait for accident analysis, here's something to chew on. So Spacecom, that is, the Isreali satellite operator, is attempting to recoup their losses. Word has it, that they told their investors, that they are asking SpaceX for either a $50 million payment, or a free launch.

So, think SpaceX will pay out or give them a free launch?

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