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Getting a 787 back in the air after a diversion

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Re: Getting a 787 back in the air after a diversion

#101

Post by ethbro »

sokoloff wrote: post #67
bitexploder wrote: post #44

Earlier quoted context omitted.

Southwest had a really memorable slogan: “wheels up” and the business really rallied around that priority ruthlessly for many years. It was pretty cool and gets used in business analysis as an example a lot about how to achieve big goals.

One such (very lightweight) analysis: https://www.cnbc.com/id/43768488 It really is a great systems thinking story. Set the overall context and goal and then figure out how to optimize for the thing that drives results.

The How I Built This podcast on Southwest [0] with Kelleher (since deceased) is an amazing episode. Both for trivia and giving context to what it takes to be successful behind the scenes.

Kelleher (a lawyer by training) ran a private practice while litigating a 3-year lawsuit against airline incumbents at the time... before Southwest flew its first flight in Texas.

And when asked "Why?" As in, why didn't you stop, return to law, or do something easier, he basically said "Because it didn't seem fair. Or right. That they could keep us from flying."

I'm sure he had his fair share of sharp business decisions, but he came across as a truly great human being.

[0] https://www.stitcher.com/podcast/national-public-radio/how-i...

Re: Getting a 787 back in the air after a diversion

#102

Post by ethbro »

_trampeltier wrote: post #77
WalterBright wrote: post #13

Back when I worked at Boeing they had the AOG (Airplane On Ground) crew to do this sort of thing. Their job was to be on call 24/7 and do whatever it took to get that airplane back in the air, and they pretty much had a blank check to do it. Naturally, they were the best mechanics Boeing had. An airplane makes money only when it is flying. When it is sitting on the ground, it loses money at a prodigious rate. A large…

"Naturally, they were the best mechanics Boeing had." I know people who do this kind of work, but are they really the best? - As long you hold a screwdriver in your hand, you are No.2 in salary. - Family, your child has birthday, something to show you in school or sport? Forget it, 5 minutes before it starts, you get always a call. So you have no family (anymore). - 9 to 5 nah.. more like 9 plus 5 hours to work a day…

Because some people will always want to be the best.

And one of the more difficult things when you're that sort of person is finding a rewarding challenge up to your skills.

Or as a president once quipped, "Why does Rice play Texas?"

Because it is hard.

Re: Getting a 787 back in the air after a diversion

#103

Post by ethbro »

WalterBright wrote: post #53
jacquesm wrote: post #52

Earlier quoted context omitted.

I didn't have airplane engines in mind when I wrote that (tanks = vehicles) but given the thread context and your airplanes reference I see how that could happen, same thing with 'block heaters' elsewhere in the thread, I take it that is in the context of other vehicles (heavy equipment, tractor-trailers, buses and so on). And yes, some airplane engines use gas but the majority of them runs something that in constitu…

Being WW2, these were piston engines running avgas.

I guess the sole redeeming thermodynamic property of the operation would be that most seals would expand as they heated?

Still, I imagine that was a "light fire, move away" procedure!

Re: Getting a 787 back in the air after a diversion

#104

Post by ethbro »

Moto7451 wrote: post #99
TeMPOraL wrote: post #92

Earlier quoted context omitted.

I imagine these 8 executives are there to lay down suppressive fire, keeping customer's management at bay so that the engineers can go in and fix the problem uninterrupted.

Hehe. The comparison is both amusing and apt. I’m often in the “executive” position in this scenario and this barrier between the angry team/customer/partner and the people doing engineering work really pays in spades. The people doing the “real” work on both sides usually avoid animosity and the management teams slugging it out in conference rooms usually understand that the dance they’re doing is just business as u…

NStD is something everyone in the business world (or who aspires to be) should read.

The fact that much of what we say, especially in times of stress, isn't what we really care about is easy to miss in actual practice.

Re: Getting a 787 back in the air after a diversion

#105

Post by m4rtink »

grogenaut wrote: post #55
weaksauce wrote: post #51

Earlier quoted context omitted.

Or an sr-71

hey at least they decided not to use hypergolic fuel in the sr-71 tho having a jet that was on fire all the time would be pretty bad ass looking. Titanium would probbably handle it and it'd eventually warm up the skin and close the gaps.

IIRC, there are some issues with Red Fuming Nitric Acid & titanium, possibly resulting in sudden explosions under some circumstances.

Hydrazine + nitrous oxide could be fine though, but better check first before use. ;-)

Re: Getting a 787 back in the air after a diversion

#106

Post by WalterBright »

ethbro wrote: post #98
CalChris wrote: post #75

Earlier quoted context omitted.

A plane sitting on the ground costs revenue. The highest revenue per hour route is JFK to Heathrow at $24,639 [1]. A 787-800 costs about $8000/hr [2]. So that's about $277/min of revenue. Yeah, $125/min sounds about right for an average route. [1] https://www.planestats.com/bhsw_2014sep [2] https://www.airliners.net/forum/viewtopic.php?t=1398091

Well, expected revenue looks a bit difference when you're leveraged to the hilt and have interest payments scheduled. My understanding is that very few airlines outright own their planes.

Even if they own the planes outright, the interest cost of the airplanes remains the same (because the money tied up in the airplane could be otherwise put to use earning interest).

For example, conventional wisdom is that owning your own home outright is a Good Thing. But if mortgage interest rates are low, taking out a mortgage and investing in something that pays more than that interest rate is a Better Thing.

Re: Getting a 787 back in the air after a diversion

#107

Post by WalterBright »

ethbro wrote: post #102
_trampeltier wrote: post #77

Earlier quoted context omitted.

"Naturally, they were the best mechanics Boeing had." I know people who do this kind of work, but are they really the best? - As long you hold a screwdriver in your hand, you are No.2 in salary. - Family, your child has birthday, something to show you in school or sport? Forget it, 5 minutes before it starts, you get always a call. So you have no family (anymore). - 9 to 5 nah.. more like 9 plus 5 hours to work a day…

Because some people will always want to be the best. And one of the more difficult things when you're that sort of person is finding a rewarding challenge up to your skills. Or as a president once quipped, "Why does Rice play Texas?" Because it is hard.

Exactly right. It's no fun getting the easy jobs. It's very sweet getting something done that everyone else said couldn't be done.

Re: Getting a 787 back in the air after a diversion

#108

Post by dredmorbius »

greglindahl wrote: post #33
jandrese wrote: post #9

Earlier quoted context omitted.

Old farm tractors used what was called "farm oil" in the old days. Basically the cheapest form of fuel you could buy since it was effectively a byproduct of the refining process. It was closer to paraffin wax than diesel, solid at room temperature. In order to start the tractor there was a second tank with diesel that was used until the engine warmed up enough to melt the primary fuel. If your tractor stalled out and…

Is this the same as the "bunker oil" burned by big ships? Wikipedia seems to think so: https://en.wikipedia.org/wiki/Fuel_oil#Bunker_fuel

Yes.

The WWII Liberty Ships utilised a triple-expansion steam engine, fired by bunker fuel. Both the expended steam and the boilers were used to fluidise the fuel to flowable tempertures -- the steam circulating either through or around the feed tanks, and the fuel line itself passing through the boiler and flame trench before final injection.

There are two remaining Liberty Ships in the US -- the John W. Brown in Baltimore, and the Jeremiah O'Brien in San Francisco.

Pay a visit and one of the engine-room crew can tell you the details.

The generaly kluginess and hackiness of the design instantly brought to mind what many software projects I've worked on might look like if physically instantiated. Though the Liberty Ship design is by far the more robust and useful than most.

Re: Getting a 787 back in the air after a diversion

#109

Post by burfog »

nemetroid wrote: post #65
burfog wrote: post #62

Earlier quoted context omitted.

If you must allow for the failure of one engine, adding more engines reduces weight. 2 engines: You need to install and carry 200% of the engine power needed to fly the plane. 3 engines: You need to install and carry 150% of the engine power needed to fly the plane. 4 engines: You need to install and carry 133% of the engine power needed to fly the plane. It is really quite interesting that twin-engine planes are che…

Flight with inoperative engine(s) is altitude constrained. The aircraft is going to be able to fly with one engine operative, but not at its usual altitude, so the 200/150/133 idea doesn’t really hold. Further, larger engines are more efficient than smaller ones. You pretty much want to install the largest engines you can fit. It’s the underlying reason for the 737 Max debacle.

Engines are sized for failure at take-off. At that time they are at maximum power, the aircraft is heavy with fuel, and the ground is mighty close.

I see no evidence that larger engines are more efficient than smaller ones. Larger total frontal area (counting all engines together) is more efficient, as is a higher bypass ratio. Both of those tend to lead toward larger engines, but you could leave those unchanged while modifying the number of engines.

For example, switching from 2 engines to 8 engines, you could maintain the same frontal area by changing the diameter from 10 feet to 5 feet. The bypass ratio, which is the portion of air that bypasses the combustion, could be 12-to-1 or 10-to-1 or whatever, and need not change with engine diameter.

Re: Getting a 787 back in the air after a diversion

#110

Post by frank2 »

dredmorbius wrote: post #108
greglindahl wrote: post #33

Earlier quoted context omitted.

Is this the same as the "bunker oil" burned by big ships? Wikipedia seems to think so: https://en.wikipedia.org/wiki/Fuel_oil#Bunker_fuel

Yes. The WWII Liberty Ships utilised a triple-expansion steam engine, fired by bunker fuel. Both the expended steam and the boilers were used to fluidise the fuel to flowable tempertures -- the steam circulating either through or around the feed tanks, and the fuel line itself passing through the boiler and flame trench before final injection. There are two remaining Liberty Ships in the US -- the John W. Brown in Ba…

American liberty ships used steam engines because US industry had been building cargo ships for the Brits and wanted to avoid the delay of switching to a more modern design. The Brits specified steam engines so they could run the ships on coal so they wouldn't have to import the fuel.
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