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-   -   Do airline pilots hypermile? (https://ecomodder.com/forum/showthread.php/do-airline-pilots-hypermile-580.html)

MetroMPG 01-08-2008 03:00 PM

Do airline pilots hypermile?
 
Do airline pilots hypermile?

Or would saving fuel cost too much money overall through lower passenger throughput (due to going slower)?

I would think that an obvious opportunity to save fuel (aside from flying slower) is in the approach to land.

I don't fly often, but have wondered:does a pilot typically make the most of the opportunity to literally glide in toward landing, or do they do the equivalent of what most drivers do: hard on the gas, late on the brakes?

Daox 01-08-2008 03:11 PM

I would think their training is centered solely on safety. This would mean doing everything gradually.

MetroMPG 01-08-2008 03:13 PM

No "death turns" then? :P

I know we have a couple of pilots here. It'll be interesting to hear about it from them.

SVOboy 01-08-2008 03:25 PM

On comercial jets they don't usually go full speed...that's how they "make up time in the air" if they depart late...I read something recently about some airport opening up new air space to allow planes to approach directly, which reduced the need to circle and therefore fuel use...so I think they try as much as safety allows.

drcoopster 01-08-2008 03:46 PM

Generally the descent is done at idle power (basically gliding) as the situation allows.

Turbine engines are most efficient (thrust per pound of fuel) at high power settings.





Disclaimer: I am a pilot.

trebuchet03 01-08-2008 03:50 PM

Larger aircraft are very unstable gliders (they're always under power - even while landing... just throttled back) :/ Going slower in flight could be an option.... That would change the cycle life of the engine (more hours = more service - luckily, turbines don't require too much in the way of service compared to other engines :p). I wonder if there's unforeseen consequences of that though - like needing more aircraft in the air to meet cargo demands...

I found an estimation of a Boeing 777-300's parasitic drag to be .0106 (just thought I'd throw that out there - seems low, but not unreasonable).

----
Here's an interesting chart (date is 2007)... I came across a fuel consumption by industry chart awhile back - and can't seem to find it again...
http://seattletimes.nwsource.com/ABP...2003859772.gif

Another interesting point (not directly related to FE) is the cooling effect from aircraft contrails... The airline grounding due to 9/11 allowed scientists to get empirical evidence that ice clouds from aircraft actually deflect some heat off the planet....

SVOboy 01-08-2008 03:53 PM

What's the difference between a personal truck and an automobile?

Who 01-08-2008 03:58 PM

Only a private pilot, but I think that only Albatrosses and glider pilots are the only real hypermilerpilots... the rest have a bit less than a 100% focus on energy conservation.

All planes have clear specifications that are quite specific on what ranges/FE they have at what airspeeds - unlike cars where it is some weird avg done on a dyno. You don't typically take any more fuel that what you'd need for a 45 minute reserve so when doing your flight plan you are extremely aware of wind speeds and directions and various altitudes and plan exactly and accordingly. The jetstream is used when favorable and avoided when unfavorable. The exchange between saved fuel and extra time would be an operational decision.

ATC controllers tend to be the bane of good mileage for airliners. They'll give them a set speed on a set vector and want the pilots traveling that speed without too much delay. Planes glide down from the cruising altitudes where thinner air helps range... few non-military planes have speed brakes, so descents are economical and well executed. Once in the pattern, planes typically fly at very inefficient speeds (flaps down)... so that planes of differing speeds are overrunning each other. In fact most commercial planes even need to use power when descending -- but it does help control and you can't control the wind when you are aiming to touchdown at a particular spot.

Planes often get straight in approaches when traffic allows. The tough part I have found is that typically all of your pre-landing checks are down on the downwind leg in slow level flight and you get used to doing it that way. When trying to do the same while maintaining a glide scope, it's change and can get a bit more intense. You are often very close before you realize you need to even start them.

trebuchet03 01-08-2008 04:03 PM

Quote:

Originally Posted by SVOboy (Post 4597)
What's the difference between a personal truck and an automobile?

My Jetta versus the F150 I'm parked next to :p

That doesn't take into consideration semi trucks or delivery trucks (although, I've been wondering if it includes fleet trucks)... I don't know if it includes SUV's - but I'm inclined to think so given the farm equipment loophole...

Lazarus 01-08-2008 04:21 PM

I don't fly for an airline( I have lots of friends that do) but I did stay at a Holiday Inn express last night.
All in all with the major carriers it is all about fuel. They plan altitude for best fuel and route with the winds aloft and aircraft weight(if there is not a lot of turbulence at the desired altitude). They will taxi out on one engine, shutdown on the end of the taxiway if excessive delays. Ask for straight in approaches, ask to keep the speed above the 250 kt limit below 10,000 ft. Of course if the airspace is saturated it's all for not but they figure that all into the planning because they are going into the same places. I know some of the overnight freight companies will give bonus to the crew if they beat the predicted fuel burn and I'm sure that is for the regular carrier too.

Here's some data on fuel. It dated (3 years old) but it will give you the general idea.

Quote:

What does a one-cent increase per gallon in jet fuel mean for a carrier like American, the
largest in the nation? Last year, American consumed 2.956 billion gallons of jet fuel. A
penny increase will jack up fuel costs by $2.5 million per month. So far, prices are 12
cents higher per gallon compared with last year. Talk about sticker shock.
As far as gliding into landing. Most turbojet engine have a lag time of about 5-13 seconds from idle to full power, depending on the engine, So if you flight idle it you would be committed from about 800 feet above the ground. It takes a while to arrest the sink rate of a 100,000 pound airplane once the engine hit max power. So they have procedures that they will have the approach stabilized at 1000 feet with power setting appropriate for the aircraft landing configuration.

Silveredwings 01-08-2008 09:34 PM

I don't know nothin' 'bout flyin' no boeings. But I do know that ATC has made me get outta the way of a scheduled, faster aircraft especially if it was on an IFR flight plan. Usually ATC frowns on planes touching each other so most of their priorities yield to the less maneuverable and faster hunk of flying metal. I've also been on my own instrument approaches (even in VMC) and been given priority landing clearances over VFR traffic. This makes sense because doing a mere prelanding checklist on a fixed gear single-engine plane for a VFR landing is trivial compared to say setting up a full ILS approach and then doing all the prelanding preparation of a complex aircraft while trying to keep the glideslope and centerline needles centered. Needless to say, holds are very expensive for folks flying the big iron.

Now something I can speak to a little better is the power required curve (or just power curve) of a plane. In non-accelerating flight, a plane must make enough thrust to equal aerodynamic drag. Drag is made of parasitic and induced drag:
http://ocw.mit.edu/ans7870/16/16.uni...s/image008.jpg
Parasitic drag goes with speed squared and induced goes with the reciprocal. Look at these two curves. Where they meet is the least drag. This is where the plane will climb the at the highest rate, and will glide the longest.

Now, look a the power required:
http://ocw.mit.edu/ans7870/16/16.uni...s/image037.jpg
The power required curve is the least where the drag is. Notice that going slower and going faster will both require more power. There is a speed called minimum controllable airspeed (MCA) where it takes full throttle to keep the plane in the air and yet the wing is right on the edge of stalling.

Ideal speeds of an aircraft are determined and published by the manufacturer after tests nearly as extensive as those that Darin does on his metro. Pilots are trained to know what to do with these speeds and to memorize them for the particular plane at hand.

MetroMPG 01-09-2008 02:59 PM

I had no idea there were that many pilots here.

Thanks for the info everyone - very interesting stuff.

Quote:

Originally Posted by Silveredwings (Post 4654)
Ideal speeds of an aircraft are determined and published by the manufacturer after tests nearly as extensive as those that Darin does on his metro.

If the quality of their data is comparable to the quality of mine... I'm never. Flying. Again. :p

Those drag curves are fascinating. Thanks for posting them.

Silveredwings 01-09-2008 09:10 PM

Quote:

Originally Posted by MetroMPG (Post 4700)
Those drag curves are fascinating. Thanks for posting them.

The induced drag is exactly why spoilers and wings will not help FE on a car (especially because their angle of attack don't go down with airspeed the way a plane's wing does). VGs create drag the same way but can be helpful in a few rare cases where there is an advantage to prolonging laminar flow instead of (earlier) airflow separation into turbulance.

RH77 01-09-2008 11:07 PM

Flyer
 
I do a lot of flying -- mostly as a airline passenger, but also on Flight-Sim (cheaper that way) :p

I read an article that American Airlines went on a quest to reduce fuel consumption a few years ago. The plan: reduce as much weight as possible.

This translated to removing non-essential equipment such as food warmers, calculate the proper amount of fuel + reserve (no more), and going as far as to justifying a profit from the in-flight magazine, or it was to get the boot.

Lightening the fleet saved the company loads of expenses. IIRC, about 10% fuel savings. As Laz mentioned, single-engine taxi is very common among all airlines. I've been in cases where the on-board power unit (a turbine-powered auxiliary power unit, or "APU") isn't used to cool the aircraft in the summer, and passengers are asked to pull the shades to help keep the cabin "hot" instead of "blistering". The big, yellow ground-air-con hose can't often handle the demand. It gets toasty, but fuel is saved...

Here's the biggest problem: With the current Air Traffic Control setup, a flight isn't "direct" -- meaning a flight from Chicago to LA isn't a straight line. So controllers can track flights with their antiquated technology, airways have to be followed, which are like "expressways in the sky". The final route will look like a jagged edge instead of a straight line. This process leads to congestion, overworked controllers, delays, vectors off-course for spacing the aircraft for landing, and speed restrictions. All of this adds up to more fuel consumed. A priority needs to be placed on updating this system, or it's only going to get worse.

Every transportation industry is feeling the fuel price pinch, and that is passed down to the consumer. Baggage weight limits have decreased, with surcharges for over-weight bags increasing. This is all with the average American weighing more every year.

Same goes for the engine itself. Northwest is the best example. I often fly on the old Douglas DC-9. The engines are old, loud, and inefficient -- but I'm sure the 35-40 year-old aircraft are paid off (they use the "Low-Bypass Turbofan" engines -- very cylindrical in appearance). In contrast, the newer Airbus A319 (similar to the Boeing 737) has a quieter, high-efficiency, "high-ratio bypass turbofan" engine. They're have the more common large intake. I'm sure they still carry a note on those...

To survive, I'm sure the trend will continue...

RH77

Silveredwings 01-09-2008 11:30 PM

It's no accident that AA planes' livery is bare skin with a stripe down the side. That much paint weighs literally hundreds of pounds.

Big iron flies almost exclusively at and above flight level 180 (18,000 feet), where IFR is required (including following airways). One of the reasons for religiously flying the airways is that the redundancy of the system. Even if ATC and all ground radar goes down or if the plane loses radio and/or transponders, traffic will still maintain minimum separation. Contrast that to South America where the radar coverage is spotty and pilots aren't so 'religious.' It's like the wild west down there and planes occasionally have mid-airs.

However we eventually update our antiquated system, it will have to account for newer and more efficient procedures that don't sacrifice safety.

MetroMPG 01-09-2008 11:54 PM

I took the controls in a 4 seat Cessna once!

(Just had to say that. Kinda feeling left out.)

Oh - and I sucked! I had quite a hard time holding steady altitude.

Silveredwings 01-10-2008 12:00 AM

Quote:

Originally Posted by MetroMPG (Post 4775)
I had quite a hard time holding steady altitude.

Once you have the altitude/attitude you want, just set the elevator trim for zero yoke force. It really minimizes the workload of holding the yoke. Then you need only make minor adjustments, and to climb or descend, you adjust the throttle for that.

Who 01-10-2008 09:21 AM

True hypermiling for naturally aspirated piston-powered aircraft would require flying in ground effect. Imagine skimming across a lake with the lowest part of your fuselage maybe 1 to 5 meters above the water depending on visibility, responsiveness of the aircraft, marine traffic and your own bravery / stupidity level. You’re brave if it works out for you, stupid if it doesn’t.

Aircraft manufacturers don’t publish consumption specs for this but pilots are trained how to take advantage of this when doing short field take-offs. The idea of a short field take-off is to get the wheels off the ground as soon as possible since the amount of drag once airborne is greatly reduced. Then the key thing is to keep the nose as close to the ground as possible. Firstly because an airplane can so easily get into ground effect – think of Bernoulli’ principle and that piece of paper being blown across a table – and secondly because an airplane that gets off the ground quickly can easily lose lift and stall a wing. You effectively lift off too soon and then force it to stay close to the ground.

Once off the ground flying in ground effect, the aircraft accelerates at its fastest rate so that you can use the speed to pull up and clear taller obstacles, or just get clear of a short or rough runway quickly. The toughest part is trying to stay close enough to the ground because as you accelerate the aircraft goes more and more out of trim and it takes a serious effort just to keep the nose down – the aircraft is fighting you to climb and you are pushing the yoke very hard towards the ground. Fun stuff… but I sure wouldn’t have wanted to be a bomber transport pilot in WWII flying 50’ above the Atlantic doing deliveries to England… no wait, that would sure be more fun than sitting at my desk job.

MetroMPG 01-10-2008 10:55 AM

Who: is ground effect so noticeable? While landing the Cessna, the pilot told me the plane doesn't easily descend through those last few meters above the runway to touch down. I've heard of the phenomenon, but I wasn't sure how much my leg was being pulled or not.

Who 01-10-2008 11:41 AM

He wasn't pulling your leg. Check out the ratings for helicopters hovering in ground effect (IGE) vs out of ground effect (OGE) - major difference.

I'm not sure what the mileage improvement from skimming across a lake would be but 30% wouldn't surprise me at all and the optimal speed for skimming would likely be faster than the maximum endurance (most economical) flying speed as well.

Silveredwings 01-10-2008 08:18 PM

Who- what you described sounded like a soft field takeoff rather than a short field one. But you're right about the way you have to push pretty hard to keep the nose level.

Anyways Metro, the reason ground effect increases performance so much is because it significantly reduces induced drag and thereby reduces the angle of attack needed to create enough lift (or vice-versa depending on your view).

Who 01-20-2008 01:04 AM

Some mention of ground effect in this Heathrow 777 Article

basjoos 01-20-2008 06:58 PM

During WWII, ground effect saved the lives of many aircrews returning to England over the North Sea in shot-up bombers with one or more dead engines and lots of added drag from the bullet and flak damage. They would steadily lose altitude until they got within 50 feet of the sea's surface, where the altitude loss would stop.

MetroMPG 01-26-2008 10:03 AM

Having spent some time on jets a week or so ago, here's a question (which I suspect may be heresy to the pilots here)...

But is it strictly necessary to take off & land into the wind? Is there a threshold wind speed below which it's not necessary?

I did notice that heading on an easterly journey with the prevailing breeze from the west, the takeoff and landing consumed extra time & fuel due to having to head the "wrong" way at take-off for some time and then turn around toward the destination.

Similarly on arrival, we had to overshoot the destination by some distance in order to turn & approach the landing into the wind.

drcoopster 01-26-2008 10:40 AM

Quote:

Originally Posted by MetroMPG (Post 7012)
But is it strictly necessary to take off & land into the wind?

Yes. Even just a 10-knot tailwind will significantly increase your takeoff and landing distances, potentially to the extent that you will not have enough room to abort or go-around if necessary. There are some very specific regulations that define how much room you must have (based on the manufacturer's official aircraft performance specifications for a particular loading and configuration). Safety is a major priority, because things do break and you always need a way out. Having the engine crap out on your car as you barrell down an onramp is inconvenient but is not likely to kill you. Having an engine crap out just before rotation speed on a runway that is not long enough (given the conditions) to abort the takeoff very well may kill you and your passengers.

Quote:

Originally Posted by MetroMPG (Post 7012)
Is there a threshold wind speed below which it's not necessary?

Yes and no. I can take off from my local airport (KGGG) in a light plane that might normally only require a 1500' distance to take off with a 20-kt tailwind because I have over 2 miles of runway in front of me. I'll have plenty of space to take off and it's not overstressing the plane at all. But the risks are higher. I'll be going a lot faster on the ground before having enough speed to take off (even though my indicated airspeed at rotation will be the same), and the consequences of a mistake are proportionately greater. The same applies for landing: the groundspeed will be significantly higher (requiring a lot more braking) and the distance required will be much longer (i.e. compare stopping distances in your car at 60mph and 80mph: the distance required at 80mph will be greater than the proportional increase in speed might lead you to believe).

Is it possible to land and take off with a tailwind? Sure, if you have enough room. Is it safe? Well ... Aircraft operators and pilots need to establish a habit and attitude of safety. Even with all of the automation and computer asisstance with which modern aircraft are equipped, a moment of inattention from the pilot can spell disaster.

With respect to aviation, safety needs to come before economy, always. I have a feeling that, in the long run, it's more economical that way.

drcoopster 01-26-2008 10:47 AM

Quote:

Originally Posted by Who (Post 4799)
I'm not sure what the mileage improvement from skimming across a lake would be but 30% wouldn't surprise me at all and the optimal speed for skimming would likely be faster than the maximum endurance (most economical) flying speed as well.

Maximum endurance speed is a bit slower than maximum range speed. Both a quite a bit slower than you'd want to be flying in a small aircraft. Check out some charts and explanation here: http://www.eaa1000.av.org/technicl/p...ormance_Charts

MetroMPG 01-26-2008 11:04 AM

Thanks for the explanation, drcoopster. I suspected as much, and picked up a few other points (eg. hadn't considered braking distances).

Who 01-26-2008 11:07 AM

drcoopster, I don't want to be disagreeable but for very large airports near large metropolitan areas, I think they tend to have preferred directions based on normal prevailing winds and desired noise reduction strategies and will often let themselves get into very mild downwind landing situations so that they don't have to reverse patterns, or annoy residential neighbors. In addition, they can also permit crosswind situations that would be treacherous for small aircraft if all they have landing there are large commercial jets.

On small airports, or airports with mixed general aviation, the wind totally rules.

Lazarus 01-26-2008 11:08 AM

Here's some more info on the tail wind. It really a matter of certification process for transport aircraft. They are only tested to a maximum component, most of the time this is 10 kts. Traffic has a lot to do with it also. You can get a landing against the flow if traffic is light or late at night and get straight in landing with a light tail wind provided as Drcoopster states there is enough runway. Depending on which type of operations you are conducting (Part 121, Part 135, Part 91) there is a whole slue of regulations, guideline and procedure both company and FAA/CAA imposed that must be followed. Most of which deal with safety.

Here's an interesting look at just how many airplanes are in the sky at a given time. So lots of time you just have to go with the flow.

8307c4 02-04-2008 10:58 PM

I've never piloted anything real but I do know a few things, as was said a steel plane with turbines off drops like a rock, pretty much, so that's no option.

With commercial airlines it is all regulated, there is this process and a procedure, I would think most pilots simply do as they're told, and for more than one reason. Safety is one but more than anything those big passenger jets are nowhere near as nimble as say a fighter aircraft or even a Cessna... That is, a mistake in the air costs a TON of fuel and time to recover, never mind economy it's the fact it takes so much fuel that only a few not so minor mistakes can put a plane's fuel levels in the critical zone, not to mention it throws it off schedule. So the big jumbo jet is roughly comparable to driving a city bus in traffic, there's just not much left in the way of maneuvers to try and save a few gallons.

Last but not least it's not their petrol, the big guys buy it and pay for it all they do is fly it, there's nowhere near the incentive to save when it doesn't come out of your pocket, no doubt there's the odd one out there who might do it out of principle and I think everyone should, but...

Look at hypermiling a car, so much of it is ludicrous, it compromises safety and even overall economy just to increase mpg... To the point a hypermiler will take the longer route because there are less stops involved and it helps on the gauge when in reality it uses more actual ounces of fuel, stuff like that.

But with all that in mind and in a plane, a smooth approach, the most direct route involving the least throttle changes makes a difference. If on landing the pilot doesn't have to adjust the throttle but once or twice and make the least amount of corrections to hit the ground at the least air speed and mostly in one smooth descent line with little in the way of altitude / aileron and flap adjustments that helps and considerably, when the wheels pop out makes a big difference as well thou a few seconds won't matter much... But I think here a pilot with experience can reduce fuel consumption, whether they do it is another story, some most likely do, others maybe, a few certainly not.

diesel_john 02-04-2008 11:27 PM

that lift takes a lot of power, that's why i don't like lift on my car.

my car can haul about 18 tons 1 mile on a gallon of fuel. (net)

a semi can haul about 175 ton miles per gallon. (net)

a train can haul something like 400 ton miles per gallon. (net)

what is the ton miles/gallon for a cargo plane. (net)

RH77 02-05-2008 12:38 AM

The best I can find...
 
Quote:

Originally Posted by diesel_john (Post 8267)
that lift takes a lot of power, that's why i don't like lift on my car.

my car can haul about 18 tons 1 mile on a gallon of fuel. (net)

a semi can haul about 175 ton miles per gallon. (net)

a train can haul something like 400 ton miles per gallon. (net)

what is the ton miles/gallon for a cargo plane. (net)

From the source I could find, (and if I'm reading the info correctly) the latest figures show

6 ton-miles per gallon (which has improved from near 2-3 since the 70's).

This Wiki entry really deserves some attention in passenger/cargo load per conveyance.

RH77

8307c4 02-05-2008 10:52 AM

Quote:

Originally Posted by diesel_john (Post 8267)
that lift takes a lot of power, that's why i don't like lift on my car.

my car can haul about 18 tons 1 mile on a gallon of fuel. (net)

a semi can haul about 175 ton miles per gallon. (net)

a train can haul something like 400 ton miles per gallon. (net)

what is the ton miles/gallon for a cargo plane. (net)

I do know from simulators, on take off a 90% throttle setting saves a noticeable if little amount of fuel vs. 100% thou all take off procedures I know of call for full throttle at least initially... So whether commercial airline pilots do this is another story, airlines may have changed the procedure thou private small plane pilots (owner-operators) might.

It might save fuel but at some point one questions the integrity of the procedure, it's one thing for a private pilot to do it because of familiarity with the plane he can always give it more or less based on his own judgment... But from a commercial stand point I am not so sure if airlines would allow this.

elhigh 02-05-2008 02:01 PM

I read just a couple weeks ago about a new concept for ATC that would have the planes flying much more directly than the current "airlanes" dictate, and would permit direct approaches as opposed to the current "stacking" model. That would eliminate a lot of unnecessary mileage right there.

I don't know as much as I'd like to about flying - esp. hang gliding - but if you want to read up on the best hypermiler jet pilot I've ever heard of, Google "Gimli Glider."

MetroMPG 02-05-2008 02:29 PM

Ah! Yes, the Gimli Glider!

I forgot to post the article here after I read it, but that plane was just retired about a week ago.

Air Canada held a special "reunion" for the crew in Montreal and/or Toronto prior to flying down to its final resting place somewhere in the US southwest.

RH77 02-05-2008 03:35 PM

Quote:

Originally Posted by 8307c4 (Post 8317)
I do know from simulators, on take off a 90% throttle setting saves a noticeable if little amount of fuel vs. 100% thou all take off procedures I know of call for full throttle at least initially... So whether commercial airline pilots do this is another story, airlines may have changed the procedure thou private small plane pilots (owner-operators) might.

It might save fuel but at some point one questions the integrity of the procedure, it's one thing for a private pilot to do it because of familiarity with the plane he can always give it more or less based on his own judgment... But from a commercial stand point I am not so sure if airlines would allow this.

I can't be considered an expert by any means -- just an enthusiast and frequent flier (including simulation).

From what I've read, to save fuel and prevent potential failures, a "FLEX" takeoff procedure is often adopted to set the throttle at a percentage of "less-than-full", based on ambient temps, takeoff weight, wind speeds, runway length, etc. etc. (FLEX is the term used by Airbus, Boeing calls it something else, but it looks like the term is interchangeable).

Most engine failures occur at full-throttle, so in addition to fuel savings, it's a safety/longevity issue as well.

I've heard that quite a few Regional Jet operators allow FLEX T/O. For larger airliners I think the flap setting can also effect it -- some aircraft are equipped with an infinite "slider" in certain ranges, instead of a notch for 1, 2, 5...etc. which may alter throttle setting. A real pilot can speak more about it...

RH77

Lazarus 02-05-2008 05:51 PM

From the article that RH77 posted a couple of post back. That show they do care about fuel.

On the operational front, many airlines:

employ single-engine taxi procedures during normal operations and selective engine shutdown during ground delays
reduce and measure more accurately onboard weight while redistributing belly cargo
tanker extra fuel on certain flights to avoid refueling at more expensive locations
cruise longer at higher altitudes and employ shorter, steeper approaches

In terms of planning for fuel usage, airlines may:

optimize flight planning for minimum fuel-burn routes and altitudes

work with FAA to change en-route fuel reserve requirements to reflect state-of-the-art navigation, communication, surveillance and wind forecast systems

employ self-imposed ground delays to reduce airborne holding
modernize their fleets with more fuel-efficient airplanes
invest in winglets to reduce aircraft drag and thereby increase fuel conservation
redesign hubs and schedules to alleviate congestion
advocate expanded and improved airfield capacity
use airport power rather than onboard auxiliary power units (APUs) when at the gates
change paint schemes to minimize heat absorption (which requires additional cooling)
pool resources to purchase fuel in bulk through alliances with other carriers

Rick is correct on the reduced power takeoff if all the factors will allow a safe takeoff.

diesel_john 02-06-2008 09:41 PM

It looks those winglets keep the air from falling off the end of the wing. If that reduces the drag, Would that same logic apply to a splitter on the bottom of the air dam on a car?

RH77 02-06-2008 10:04 PM

Quote:

Originally Posted by diesel_john (Post 8602)
It looks those winglets keep the air from falling off the end of the wing. If that reduces the drag, Would that same logic apply to a splitter on the bottom of the air dam on a car?

I think these apply mostly to airfoils and lift. Some advanced spoilers for ultra-high speed operation (such as the upward extension of some rear spoiler for 100 MPH+ operation -- similar to winglets). These decrease FE with downforce: a trade for traction.

Experts in Aero can attest, reducing frontal area and drag is of the utmost. Winglets likely will not accomplish either in lower-speed applications.

RH77

MetroMPG 02-18-2008 11:13 PM

To answer the original question... (sort of)...

Yes, Virginia, some pilots DO hypermile...


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