Is this a good way to save fuel?

Zorba · Post by **Zorba** » 07 Aug 2006, 17:59

Following a topic on A.net ( http://www.airliners.net/discussions/ge ... n/2922867/ ) I was thinking about another way to save fuel during taxi.

Wouldn't it be possible to create some kind of "roller-coaster" system where the nose gear has to be placed in a chain which moves along the taxiways and can be programmed either by plane or by gate. (some kind of railroad system)

Is there any way this could be implemented on an airport? I think the costs are not that high to create such a chain around the airport.

Stepha380 · Post by **Stepha380** » 07 Aug 2006, 18:17

As said in the airliners topic, it is impossible to tug a plane at full taxi speed on a long distance, because of the strain imposed on the front landing gear.

It seems true to me, because the 747 are moved very slowly in LHR when they need to be moved from one side of the airport to another (a few km).

If you install an APM (Automated Plane Mover), you need to install rear view mirrors to check the engine run-up, don't you ?

A318 · Post by **A318** » 07 Aug 2006, 22:28

Delta is saving a lot of fuel since they only use one engine during taxiing to and from the runway.
It's simple, smart and with a huge fleet as Delta has it really makes a difference.

Greetz,

Erwin

Advisor · Post by **Advisor** » 08 Aug 2006, 10:09

Cant u taxi the a/c till the runways....

Stepha380 · Post by **Stepha380** » 08 Aug 2006, 10:41

Advisor wrote:Cant u taxi the a/c till the runways....

yes you can, they did for the 777-200LR record flight, it takes more time.

If you want to do it for all departing and arriving planes, you need more people, more materials, a review of all the airports procedures, a will from all the airlines operating out of one airport, APU have to work fine. Engines must run at least 4 minutes before full thrust.

A lot of airlines already taxi on one engine and it seems to work well.

Another idea may be, taxi with one engine to join the queue for departures, cut the engines, move the planes with a rolling floor, start the engines four minutes before the expected departure time. Crazy idea anyway

744rules · Post by **744rules** » 08 Aug 2006, 12:21

Another way to save fuel is the loading. Aft CG saves fuel, but this is not always possible due to a number of reasons

teddybAIR · Post by **teddybAIR** » 08 Aug 2006, 12:23

Stepha380 wrote:As said in the airliners topic, it is impossible to tug a plane at full taxi speed on a long distance, because of the strain imposed on the front landing gear.

It seems true to me, because the 747 are moved very slowly in LHR when they need to be moved from one side of the airport to another (a few km).

If you install an APM (Automated Plane Mover), you need to install rear view mirrors to check the engine run-up, don't you ?

Well, if it's not possible with the nosegear, then why not consider the main landing gear to hook up on such a system? Anyway, I think such a system would come out to be more costly than just taxi on the engines, as the chain also needs to be powered and the airports are very unlikely to offer such a service for free, don't you think. And I didn't even speak about the initial investments...

fokker_f27 · Post by **fokker_f27** » 08 Aug 2006, 12:45

I think Delta's way is still the best. I have seen many airlines do it with turboprops. I do it sometimes in FS. It works fine, so why not make it standerd for all airlines?

earthman · Post by **earthman** » 08 Aug 2006, 12:57

Stepha380 wrote:
Advisor wrote:Cant u taxi the a/c till the runways....
yes you can, they did for the 777-200LR record flight, it takes more time.

If you want to do it for all departing and arriving planes, you need more people, more materials, a review of all the airports procedures, a will from all the airlines operating out of one airport, APU have to work fine. Engines must run at least 4 minutes before full thrust.

A lot of airlines already taxi on one engine and it seems to work well.

Another idea may be, taxi with one engine to join the queue for departures, cut the engines, move the planes with a rolling floor, start the engines four minutes before the expected departure time. Crazy idea anyway

Why not add a (steam or electromagnetic) catapult on the runway, while we're at it? Doesn't have to accelerate as fast as on an aircraft carrier, because the runway is long enough anyway.

trikkke · Post by **trikkke** » 08 Aug 2006, 15:28

what about electric semi-robotic tugs?

they just need to be hooked up at the gate and are remotely controlled by the pilots, so there is no extra ground personnel needed.

the tugs would be monitored by the pilots through camera's (mounted on the tugs or on the plane)

when arriving on the hold position, the tugs are told to disconnect by the pilots and to return automatically to their base station (by following an underground guidance cable), where the batteries could be recharged.

this way you get the advantages of the system boeing is developing (electric motors on the front wheels) without having to carry the weight of this system when airborne.

grtz,
trikke.

Stepha380 · Post by **Stepha380** » 08 Aug 2006, 16:48

trikkke wrote:this way you get the advantages of the system boeing is developing (electric motors on the front wheels) without having to carry the weight of this system when airborne.

Do you have more details about the Boeing system, in my opinion it would just be for pushback, not for taxi.

trikkke · Post by **trikkke** » 08 Aug 2006, 17:50

Do you have more details about the Boeing system, in my opinion it would just be for pushback, not for taxi.

info about the boeing electric nosewheel tests: http://www.boeing.com/news/releases/200 ... 0801a.html

grtz,
trikkke[/quote]

Stepha380 · Post by **Stepha380** » 08 Aug 2006, 18:02

Thanks for the link although it's too bad they don't speak of the taxi speed

Captain · Post by **Captain** » 09 Aug 2006, 22:51

What's the estimated percentage of fuel consumed whilst taxiing (with both engines). i.e for a A320 or 737 for a short flight from BRU to LHR or FRA

Captain

744rules · Post by **744rules** » 09 Aug 2006, 22:55

the taxi fuel is always added as a fix amount. This can be different according to a/c, airport, company,....

average taxi fuel is +-
a320 200kg
b737 230kg
md11 500-800kg
b747 1000kg

Advisor · Post by **Advisor** » 12 Aug 2006, 10:09

744rules wrote:the taxi fuel is always added as a fix amount. This can be different according to a/c, airport, company,....

average taxi fuel is +-
a320 200kg
b737 230kg
md11 500-800kg
b747 1000kg

that is a lot to waste, dont u think so.......

SN30952 · Post by **SN30952** » 12 Aug 2006, 11:35

Stepha380 wrote:
Advisor wrote:Cant u taxi the a/c till the runways....
yes you can
A lot of airlines already taxi on one engine and it seems to work well.
Another idea may be, taxi with one engine to join the queue for departures, cut the engines, move the planes with a rolling floor, start the engines four minutes before the expected departure time. Crazy idea anyway

Why not build sloping taxi ways?

earthman wrote:
Stepha380 wrote:
Advisor wrote:Cant u taxi the a/c till the runways....
yes you can,...
Why not add a (steam or electromagnetic) catapult on the runway, while we're at it? Doesn't have to accelerate as fast as on an aircraft carrier, because the runway is long enough anyway.

Why not build sloping run ways?

n5528p · Post by **n5528p** » 21 Aug 2006, 10:31

SN30952 wrote:Why not build sloping taxi ways?
Why not build sloping run ways?

Are you kidding?

Bernhard

David747 · Post by **David747** » 21 Aug 2006, 11:06

Correct me if I'm wrong, but the fuel that is burned by a plane during taxi to the runway is excess fuel, without burning this fuel the aircraft will be too heavy for take off.

David747 · Post by **David747** » 21 Aug 2006, 11:08

another thing, if planes are taxied to the runway by some system, how will it save companies fuel expenses? they will still need the fuel to get the plane airborne, and as we can see, jet fuel is expensive all around, a few pounds of jet fuel being saved during an automatic taxi will not make much of a difference.