09L please driver!!

Nigel H-J · Post by **Nigel H-J** » 12 Dec 2006, 12:34

Well, at least it's a start and will save around two tonness of fuel not to mention a 0.00009% saving on emmissions

http://news.bbc.co.uk/1/hi/sci/tech/6170999.stm

jonesey2k · Post by **jonesey2k** » 12 Dec 2006, 12:59

Yeah right, I can see that working at busy hubs

Post by **Garry Russell** » 12 Dec 2006, 13:34

They used to do that years ago but gave up because it was impractical

It was in the US, don't know how many airports tried it, where they were towed and waited in starting bays near the end of the runway.

Brymon used to start two sometimes only one engine on Dash Sevens or a while and get the rest going on the taxy out as did BMA when they would start only the inners on the Viscounts.

That was given up as well

As was Lufthansa's fuel saving 727 approach where instead of flying slow and on high power with flaps, stayed clean and high, well throttled back then descended rapidly with flap and less power due to the descent...

Doesn't work at busy airport with other aircraft in a line
:think:

Garry

Charlie Bravo · Post by **Charlie Bravo** » 12 Dec 2006, 14:20

The taxi fuel on the F50's at work is only 50kg

DanKH · Post by **DanKH** » 12 Dec 2006, 14:30

Why not tow them the whole way?

Imagine the amount of fuel THAT would save!.

No-one mention the amount of fuel used by the tow truck, but I guess that's a completely other story....

TobyV · Post by **TobyV** » 12 Dec 2006, 18:28

This isnt half as daft as it may sound, impractical, quite probably, but even the small sounding savings are significant, for example:

During taxiing and idling on the ground, because of fact the engines are operating well off design, there is a large presence of UBHCs (unburned fuel) in the exhaust. It is this that often causes the smell of kerosen around airfields.

The varying thrust levels, off design operation and low forward velocity mean that the engine is inefficient on the ground and may also be emitting more noxious chemicals other than than the usual CO2 and water than during cruise.

Even a small improvement in fuel efficiency (or reduction in operation) will result in savings in fuel equating to millions of Pounds a year with the corresponding savings in consumption and emissions. In the turbine industry, we might for example work very hard to achieve a 0.5% or 1% improvement in engine efficiency which would, over time and multiplied by the number of engines, have savings of this magnitude.

How they put this into regular practice at Intl. airports is quite another matter

Jetset · Post by **Jetset** » 12 Dec 2006, 18:35

One of the biggest problems that will come from this is man power. I am sure our CB will agree on this also. Sometimes, especially during busy periods it is difficult enough to get a push back crew as it is, never mind getting them to take the aircraft to the runway for starting. Then there is the problem of getting the equipment back from the runway area to the ramp, especially if aircraft are waiting behind the aircraft being towed, as taxi ways are too narrow to safely navigate back.

If this plan went ahead, alot more tugs would be needed, only increasing tug fuel emissions, which can be really bad, especially on older models.

jonesey2k · Post by **jonesey2k** » 12 Dec 2006, 18:56

Should just have the APU going and have electric motors on the nose wheels or something.

Charlie Bravo · Post by **Charlie Bravo** » 15 Dec 2006, 09:20

I agree with what Jetset said.

The handling costs would also go up as they will have to employ tug drivers and obviously get new tugs in.
The money saved will soon be spent again.

DispatchDragon · Post by **DispatchDragon** » 15 Dec 2006, 10:02

Consider this:

Atlanta Hartsfield has three departing runways operational at anytime
, there are during any given hour 60-100 departures - it would take
something on the order of 10 - 15 minutes for each tug to tow ONE acft
to the departure end of the runway - during the peak periods at present
aircraft are lined up on pararell taxiways the entire length of the runways
waiting to take off - each tug requires 2 men - a driver and someone to remove the tow bar and pins which can take 90secs to 3 minutes depending on type - so you need oh lets say being conservative 50 tugs
and 100 men per hour - the cost alone makes this sort of idea totally
impractical - and the cost ......well we all know who pays for that dont
we??? the passengers.......BTW I didnt even touch Denver where the departure ends of the runways can be 3 miles from the terminal.....
Tugs arnt know for being fuel efficient either.

Dont think it will happen anytime soon

BTW - slowing departure rates wouldnt help either with an ATC system
that is already choked

Leif