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Old 08-20-2015, 10:41 AM   #1
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Rickb and the 787

Hey Rick, I don't come in this area anymore. I just remember a few years back we were having the discussion and you could not see where the increases in efficiency were coming from. The "sum of the parts" did not add up for you. Well after our airline has flown them awhile, I figured out where the numbers were coming from....ALTITUDE!!! While the sum of the parts did not add up to the efficiency numbers that were quoted. But what they did add up to was the airplane's ability to climb straight to altitude. That is HUGE!!! If you load up any "conventional" widebody for the mission that it was designed for(ie 777 EWR-HKG), it will have to step climb all the way to the destination. It's first altitude may be FL300(maybe even lower). And FL320 in a couple hours and so on. Whereas the 787 can just climb straight to FL410 and stay there the entire trip. It is mostly a function of the lightweight carbon fiber construction and the wing. But all that other stuff helps incrementally as well. Are we getting the numbers that Boeing quoted during the propaganda campaign??? Pretty much. I know we are quite happy with them. "Game Changer" is what our marketing guys call them. Anyway, just popping in to give a progress report. And I might be (involuntarily) flying one soon. Shrinking Houston and might lose my left seat. All part of the "fair and equitable" merger!!!
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Old 08-20-2015, 03:28 PM   #2
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John--- Last year I was sent to England, Poland, and Mexico to interview the CEOs and passenger service directors of airlines that fly the 787. They absolutely love them. Not only are they turning in better than forecast efficiency in terms of fuel burn but they are proving to be extremely popular with their passengers.

The CEO and maintenance director of one airline told me that their operations folks had to go back and completely rework their fuel burn calculations because the figures they had been using, which were based on our own fuel burn predictions, turned out to be too conservative. So much so that they initially simply didn't believe the fuel burn numbers they were getting from the planes. When they determined that the numbers were real, they redid all their route calculations and as a result they've been able to put their 787s on routes they initially hadn't thought they could use them on.

The really nice thing to hear was that all the hype we generated (some of it by me) about how fabulous the cabin environment was going to be is proving to be right on the money. The passenger service director of AeroMexico told me that their passenger surveys show that passengers who fly on both their 767s and 787s are even convinced the food is better on the 787s. But it's the exact same food. He flies a lot on their airplanes in the course of his work and he said that he, too, thinks the food tastes better on the 787.

The CEOs in Europe all spoke about how their passengers are reporting far less jet lag effects from the 787's lower cabin altitude and higher air humidity.

And all the CEOs and passenger service directors said that they are getting more and more passengers booking specifically to fly on their 787s instead of the other planes in their fleets.
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Old 08-20-2015, 08:28 PM   #3
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Yesterday I got an email from Qantas, boasting about their improved profitability. It was as much due to lower fuel costs and a tanked A$ as their cost reduction efforts, but nonetheless quite important.

In the email they trumpeted that they will be taking delivery of 8 789-9's in 2017. Now I know why they made a fuss, since prompted by you guys above as well I've just reviewed a bunch of info on the 787. An important new aircraft, and the cabin pressure and humidity improvements are a big deal. I just hope the 787 is on the routes i want to fly. If they are running all LiFePO4 battery chemistries by then I'll be even happier.
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Old 08-21-2015, 03:20 AM   #4
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Qantas has always been a leader in adopting or developing new technologies. They were one of the first airlines to start ordering all their new 737s with winglets. While the winglets were developed by the BBJ (Boeing Business Jet) program the drag reduction/ fuel savings they found during the flight test program was so impressive, exceeding 6 percent in some cases, that we began offering them to the airlines, too. They are very expensive so a lot of airlines like Alaska and Southwest said they'd never order them as they didn't think the payback would be there.

The first airline to order 737s with winglets was Air Berlin. Qantas was among the next airlines to opt for them. I produced a marketing video about Qantas' use of the 737 and they told us the winglets were saving them millions each year in fuel costs. Where they really pay off is on longer flights like trans-Australia but Qantas was ordering winglets on all their 737s, even the ones intended for shorter runs.

Today, of course, virtually every airline gets winglets on their new 737s.
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Old 08-21-2015, 11:13 AM   #5
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Qantas has always been a leader in adopting or developing new technologies. They were one of the first airlines to start ordering all their new 737s with winglets. While the winglets were developed by the BBJ (Boeing Business Jet) program the drag reduction/ fuel savings they found during the flight test program was so impressive, exceeding 6 percent in some cases, that we began offering them to the airlines, too. They are very expensive so a lot of airlines like Alaska and Southwest said they'd never order them as they didn't think the payback would be there.

The first airline to order 737s with winglets was Air Berlin. Qantas was among the next airlines to opt for them. I produced a marketing video about Qantas' use of the 737 and they told us the winglets were saving them millions each year in fuel costs. Where they really pay off is on longer flights like trans-Australia but Qantas was ordering winglets on all their 737s, even the ones intended for shorter runs.

Today, of course, virtually every airline gets winglets on their new 737s.
Today of course, we are removing old winglets for scimitar winglets.
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Old 08-21-2015, 11:27 AM   #6
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And I'm not so sure about Quantas as the trailblazer on winglets. We were the launch customer for the nextgen 737s and while the first 10 -700s came without them, the rest came with them. That was 1997-98.
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Old 08-21-2015, 11:48 AM   #7
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Qantas had them before that, I believe. They weren't the first to get them, but they were ordering them while most other carriers, particularly in the US, were still saying they weren't worth the price. I believe the current interim scimitar blade is added to the existing winglet but I could be wrong about that. The new 737MAX (first fuselage arrives tonight or this weekend) has an all-new winlet design.
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Old 08-21-2015, 12:09 PM   #8
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A bit off topic, but I have a Q about how we ended up with cruise flight levels where we do: Most seem about 33 to 40,000ft. I know wing lift drops with altitude, and engine thrust drops with altitude, but drag also drops with altitude. So it makes sense that there is a limit to cruising alt. But is that 33-40 zone really optimal? Could higher and faster be more efficient? Or higher and somewhat slower with more wing area.

I guess if I wanted to answer all that, I could have gotten an Aero Eng degree!!

Always curious of this while flying.

And Kudos to Boeing on the 787. Sounds like it is proving to be a winner.
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Old 08-21-2015, 02:29 PM   #9
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Ski, everything you said plays into it. The one important thing you are missing is L/D Max. LD Max is the point where maximum lift is generated for the least amount of drag. On a graph, where the drag line intersects the lift line. That usually occurs very close to stall speed. As we climb, the air does get thinner and we actually are pretty damn close to stall, and therefore LD Max. We just need more margin for safety reasons so we are not right at it. But as close as safely possible. In my example, they are close to LD Max at the lower altitudes but fuel burn at those altitudes are higher. Anyway, I am pretending to know what I am talking about.... As far as wing shape, it is really more a function of wing loading. The higher the wing loading, the closer to LD Max. The regional jets you see flying around have very low wing loading and therefore are not really efficient at all. An Emb145 will be burning about 3400pph at cruise whereas I can fly a 737-800 and be burning 5500pph carrying 3x as many people. That high burn rate on the RJ is due to their wing loading...of lack thereof. So a stubby fat wing would be slow AND inefficient.
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Old 08-21-2015, 02:38 PM   #10
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Another thing that most people don't realize is that the 777 in my example is not stuck at the lower altitudes due to a lack of power or the inability to climb. It is an aerodynamic limit. Basically the buffet margins of low speed buffet/stall and high speed buffet. As fuel is burned, those buffet margins decrease and allows the plane to climb. The the weight and wing on the 787 allow it to climb to higher altitudes right away and that is where the efficiency is gained.
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Old 08-21-2015, 08:40 PM   #11
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Thanks. That high speed buffet- is that what you get as you approach Mach 1? As I recall actual speed of sound is a function of temperature, not altitude, but can't remember if it gets higher with cold or lower with cold.

Fun stuff.
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Old 08-21-2015, 09:01 PM   #12
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The 777 cruises at about Mach .85. At least that's what Emirates cruises them at.
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Old 08-21-2015, 11:27 PM   #13
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Qantas held off ordering 787s until they got out of a financial hole, improved their credit rating and reached a deal with flight crews on pay. Though I think their budget subsidiary Jetstar already flies them. No dividends paid for years, it turned a 2Bn+ loss last year to a 500M+ profit and promised a capital return of 23c p/share instead of a dividend this year. Due to smart(or lucky) fuel cost hedging it is already getting the benefit of reduced oil prices. At one point the entire airline was grounded on a few hours notice, planes scattered all over the world, Qantas says over a staff/union disagreement, there was a massive kerfuffle over that. Let`s hope the worst is behind "The Flying Kangaroo". I think it still holds the record for the longest nonstop 747 flight, London to Sydney.
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Old 08-22-2015, 01:57 AM   #14
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Thanks. That high speed buffet- is that what you get as you approach Mach 1? As I recall actual speed of sound is a function of temperature, not altitude, but can't remember if it gets higher with cold or lower with cold.

Fun stuff.
Mach is a function of temperature only!!! The colder it is, the slower the speed of sound!!
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Old 08-22-2015, 07:46 AM   #15
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I just remember a few years back we were having the discussion and you could not see where the increases in efficiency were coming from. The "sum of the parts" did not add up for you. Well after our airline has flown them awhile, I figured out where the numbers were coming from....ALTITUDE!!!
Ah so ... thanks for the update, that is a factor I did not consider.
Avoiding the the step climb makes a lot of sense. Do you reduce power during the climb so you end up at cruise power at cruise altitude or just go for altitude if ATC allows and accelerate to cruise speed before backing off?
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Old 08-22-2015, 10:49 AM   #16
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Ah so ... thanks for the update, that is a factor I did not consider.
Avoiding the the step climb makes a lot of sense. Do you reduce power during the climb so you end up at cruise power at cruise altitude or just go for altitude if ATC allows and accelerate to cruise speed before backing off?
You go to climb power and climb at your cruise speed. So let's say you're climbing thru 20,000 feet at 300 knots. You hold that 300kts until you transition to Mach. On the climb page in the FMC it would look like 300/.80. 300 knots at 20,000 feet is probably about .65. Just a WAG. Probably in the upper 20s you'd hit .80 and then hold that is indicated airspeed would then bleed off. Just an example....80 in the upper 30s is probably somewhere around 250 knots indicated. Even though your true airspeed would be around 460. Hence the reason we fly Mach as we get higher instead of indicated airspeed.

So to answer your question briefly, we do not slow down to climb. Technically we can't. The wing will become to much of a load for a slower speed. So we have to climb at our computed cruise speed due to buffet margins as we near cruising altitude. I hope this makes sense.
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Old 08-22-2015, 11:48 AM   #17
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Sounds like there must be quite a calculation to arrive at actual Mach. Pitot tube gives two pressure readings, but as alt goes up, readings on both drop, so actual airspeed has to be corrected. Then need actual temp too. But temp readings will rise from aero friction. I guess with those numbers that is all you need, but will need some crunching.
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Old 08-22-2015, 12:15 PM   #18
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Given the computing power of planes these days i suspect all the pilot has to do is not kick the plug out of the wall. A good friend is the chief pilot for the Everett flightline so flies 787s, 777's and 747-8s on a daily basis. Before that he was the assistant chief production pilot for the 787 program. He told me that the 787 is a very nice plane to fly but it's more like playing a video game than flying an airplane. He said all these planes pretty much fly themselves. So no human calculations needed.

Too give you an idea of where the industry is headed, i just finished a video about a new product that connects an iPad wirelessly to the airplane's flight management system. The application on the iPad shows the flight crew in real time the plane's actual fuel usage vs. the planned usage and how it will change if they change different parameters in their flight plan enroute. The fuel savings this makes possible are substantial. Pretty cool deal.
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Old 08-22-2015, 01:03 PM   #19
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Always had a soft-spot for Boeing planes. All the crew, both injured and healthy, had time to bail out after B-17G 44-6463 of the 839th bombing squadron received a direct AAA hit behind engine no. 3 immediately after dropping 1000-pound bombs on Merseberg, Germany. This occurred two years before my conception. My father was co-pilot.
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Old 08-23-2015, 01:15 AM   #20
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Sounds like there must be quite a calculation to arrive at actual Mach. Pitot tube gives two pressure readings, but as alt goes up, readings on both drop, so actual airspeed has to be corrected. Then need actual temp too. But temp readings will rise from aero friction. I guess with those numbers that is all you need, but will need some crunching.
Marin is correct. The airplane does it for you. But you do hit on some important points. Indicated airspeed becomes less reliable mostly because of compressibility issues. Basically, the tube fills up and it can no longer measure pressure accurately. Another measure of temperature we us is Total Air a temperature. And it incorporates aerodynamic heating Into the figure. So there are numerous temp readings and numerous different airspeed definitions. So while the airplane might do the computations, you still need to know what they mean.
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