Reffro

The figures will be based on a comparison between everyone on the plane driving the same distance individually in a car versus taking a plane.

300 people each in their own car driving 3000 miles at 25 mpg (reasonable touring figure for a scoob) will use 300x(3000/25)= 36,000 gallons of fuel. Even with four people in each car it would be 9,000 gallons used.

The comparison therefore looks pretty good, when you cansider that driving at 70mph average it will take just under 43hours to cover the same distance in a car, versus the 6 hours of a plane, which uses less fuel to transport the same number of people and their luggage. Therefore the pro-rata amount of fuel used by the plane to transport one person the 3,000 miles is equivalent to what would be used by a 100mpg car, if that same person drove themselves.

[Edited by Reffro - 6/4/2003 9:47:54 AM]

Luke

Tonights "Airport Doc"

Did i hear that correct????? At 38000 feet that Airbus (??) get near 100 MPG!!!!!!!!!!!

I know take off the plane will drink the fuel.......... But 100mpg


Just going to clean ears....Just in case!!

RON

Somethin like that, hard to beleive innit!!!

Luke

Its bloody mad........!!

DaveD

iTrader: (2)

Er, don't think so....

Recently ran a static engine test (at sea-level) with one of the most effecient large jet engines in the world (as fitted to A340), and in 200 hours running it burnt....

























1.2 million litres of fuel!!!

Not too bad when you can get Kerosene for 7p per litre.


I'll see if I can find some (estimated & completely unofficial) mpg figures tomorrow

cletterridge

Absolute crock! 100 miles is ten minutes travel time at those speeds - do you really think two massive jet turbines only use half a gallon each in that time? No chance! A microlight with a glorified strimmer engine can only just manage 50mpg.

I've got a mate who is 'Mr Gas Turbine' and he says it's actually more like 0.3mpg for a jet this size. He also told me that when Jumbo jets are fully fuelled, they're too heavy to fly but use so much fuel taxi-ing out of the slot and accelerating that they're below legal maximum take off weight by the time they get to the end of the runway!

fatherpierre

When I worked on E3Ds about 10 yrs ago they cost an estimated £10000 per hour in fuel costs just to be kept airborne.

cletterridge

Just remembered when a guy I used to work with told me that he'd been speaking to a BA pilot who'd told him that his 737 could manage 0-60 in 0.8 seconds on takeoff. And he completely BELIEVED him!

Can you imagine the health and safety issues if you really were exerting top-fuel funny-car dragster style forces on elderly passengers? He still wouldn't listen, so I reminded him it takes at least 25 seconds to get to the end of the runway at take off speed of around 180 - so 0-60 is only around 8 seconds, or hot-hatch speed at best!

Point is: Don't ever believe anything a pilot tells you! (and some people are too gullible ;-) .)

fatherpierre

Maybe the Airbus in question was the flat diesel version

Luke

Clean ears !!

midget1500

doh! didn't realised you had double posted. yeah, as i said, there is no way in hell it is 100mpg. more like xx gallons per mile.

midget1500

totally unscientific numbers follow...

based on DaveD's figures, a 6 hour flight from uk-florida (3000 miles) at a constant fuel usage would use 36,000 litres (7919 gallons) therefore you would get around 0.38MPG!! a far cry from 100mpg! well done to cletterridge who said 0.3 - not far off, even from these unscientific figures

steven

Alpine99

perhaps they knock them out of gear and glide a bit... it is downhill

Fuzz unplugged

100 miles to the gallon LOL

More like 100 gallons to the mile

Andy

Luke

I knewqit sounded mad.......... But would like to listen to that programme again just to hear what exactly he did say!!

TopBanana

LOL @ Alpine

ChrisB

DaveD, do you work for RR?

SPEN555

What if the plane was in a jetstream? Could it effect the mpg to get it up to 100mpg. From memory the jetstream has 500mph winds so it's for sweet FA.

Damian.

Luke

Its driving me mad.............

Why dont they build motorways at that hieght????

rik1471

He stated the 100mpg was only attainable at 38000ft, must be something to do with reduced friction.

Flyboy-F33

My plane will get me from Blackbushe to Sheffield in about 1 hour exactly, in that time it will burn about 50 ltrs of Avgas (9.5 galls) If I went by car it would take 3.5 hrs (if I am lucky) and my car would use 9 galls, so...no contest!

The guy on th TV the other night didnt mean the A330 did 100MPG, that would be impossible. What he was saying is that the cost per passenger mile is equivelent to a car doing 100mpg.

Flyboy-F33

ANd another thing....!

The previous poster who quoted the fuel burn for 200 hrs also stated in brackets at sea level....The fuel burn decreases massively at altitude due to reduced skin friction and reduction in air density (the second factor has the biggest impact)

Luke

F33


Thats right........ Exactly what the pilot was saying


Cheers

TopBanana

Blackbushe to Sheffield in 1 hour - sweet!

Peter_B

Absolute tosh!! There's no way that an airliner could cruse at 100mpg.

However on a different thread, the space shuttle will do about 25 mpg cruising at mach 28 over a 3 week mission!! Obviously this is the fuel used to launch it into space, averaged over the mission as it doesn't use any fuel when in orbit.

That's about the same as a scoopy uses when cruisin at mach 0.1!!

Flyboy-F33

Dont you just love people who read the first post, then go straight to the end and post a reply before bothering to see if anyone had a sensible answer..! Muppet...springs to mind.

SiDHEaD

And on their first post as well...

Leslie

A jet aircraft will cover more distance for less fuel at high level. The indicated or pressure airspeed at cruise will affect the airframe drag experienced. Because the air changes density at different heights the indicated airspeed changes its relationship to the true airspeed as the aircraft climbs. At sea level say an indicated airspeed of 250 knots will be similar to the true airspeed. At 40,000 feet an indicated airspeed of 180 knots can be equivalent to a true airspeed of 420 knots dependent on air temperature. The true airspeed is basically the speed of the aircraft relative to static air. This would be the same as the groundspeed ignoring wind effect.

A jet engine will work best at a certain speed known as the design RPM. This is the engine speed for best efficiency of both the compressor and the turbine sections of the engine. The thrust required to drive the aircraft at the most efficient airpeed or Mach number can be achieved closest to the design RPM at high altitude. So fuel consumption per mile will be lowest at higher altitudes.

An average passenger aircraft will use about 80,000 lbs weight of kerosene to cross the Atlantic. The fuel weighs approx 8 lbs per gallon. If you are lucky enough to find a jet stream wind behind you then your groundspeed can be increased by anything up to 150 Knots. But you have to avoid the Clear Air Turbulence that is often associated with these kinds of thermal winds.

The pilot was talking about passenger miles per gallon,assuming his aircraft was full as was mentioned.

Les

cletterridge

If you want a real 100mpg, you're going to have to drive one of these....

http://www.benerridge.freeserve.co.uk/econ10.htm

Leslie

Les