burn per km per passenger

[divinehover]

There is a lot of talk about 3litre per km per passenger aircraft coming onto the market. I have tried doing simple arithmatic to work out what my a/c uses but don't seem to get realistic figs. Does anyone out there no how to work this out (I thought it would be rather simple)?

Here is a example if it will help someone explain.

A319-131 (120 pax)
320nm trip dist
1950kg burn off

This is quite a short sector so it's maybe not a good example.

[The SSK]

The standard measure of (car) fuel efficiency in Continental Europe is litres per 100km. So a relatively thisty car (like mine:sad: ) might do 10, a diesel with decent performance (say a BMW 320d) would be touted at about 6.5, a Prius I believe is supposed to be down at 3.5 and they are talking about the next generation of super-efficient cars getting down to 3.

Obviously, with just one occupant (ie load factor of 20%) these figures are equal to litres per 100 passenger-km.

Without looking up the figures, I believe that a representative figure for a long-haul flight in a modern aircraft with a typical l/f would be about 4 or 4.5 which would be as good or better than a VW Golf on a long journey. Next generation aircraft will hopefully get that down to 3 (better than a Prius!)

[Rainboe]

Looks reasonable. 6kgs/mile at about 450 nautical miles/hour, about 45kgs/min overall- additional cruise about 40 kgs/min
(multiply kgs by 1.25 to get litres)

[StainesFS]

Assume that the density of kerosene is 0.81 kg/litre. Conversion factor 1nm = 1.852 km.

Fuel burn in litres = 1950/0.81 = 2407 litres.

Distance in km = 320 * 1.852 = 592.6 km.

Passenger kilometres travelled = 120 * 592.6 = 71,112.

Fuel burn, in litres, per passenger per kilometer = 2407/71,112 = 0.0338.

I think that the fuel burn per 100 km mentioned by the earlier contributor is the correct figure to use. Correspondingly, fuel burn per passenger/100 km = 0.0338 * 100 = 3.38.

About a 10% saving to go then for short haul. Perhaps professionals (not this wouldhavelikedtohavebeen (too old to be a wannabee!)) with similar data for medium or longhaul could provide such data to see if B777s etc are already down to the 3 mentioned in the original post.

[Old Smokey]

Something not to be forgotten if you're doing a comparison between automotive and aeronautical fuel efficiency, is that road distances are, on average, 1.5 times that of air distances.

Thus, for a realistic comparison, the aircraft's consumption / 100 Km may be factored by 2/3 for a fair comparison.:ok: :ok:

Regards,

Old Smokey

[Strepsils]

Old Smokey - Why:confused: Miles per KM per pax is miles per KM per pax. Doesn't matter if the road route is longer, all that means is the car uses more fuel to travel more miles. You'll still get the correct litres/KM.

[OverRun]

Old Smokey,
Thanks - good point which I hadn't realised, and entirely pertinent in these comparisons.

[jabird]

Os, this is a very interesting point, but where does the 1.5X figure come from?

I could see that applying on comparisons from London anywhere on the continent where the land route involves a long kink via Dover or the Channel Tunnel, but does it really apply on, say, London to Manchester?

Planes don't always fly direct either - there are always ATC issues, together with the possibility of stacking, changes in wind direction etc.

[mbcxharm]

Strepsils:
Because all other things being equal we have to account for the fact that air transport can take more direct routes from A to B and is hence more efficient in this regard. As Old Smokey says, this makes for a fairer comparison.

Personally, I would dispute the x1.5 figure. If a car followed a zig zag route making 90 degree turns once in a while whilst an aircraft went in a straight line the car would do sqrt(2) more distance than the aircraft - another 40% or so. I would say therefore that a figure more like x1.1-1.3 would be more appropriate.

It doesn't feel like I'm going to most direct route from the Canaries to Newcastle, however, when we come off the Tango routes and go WAL-POL-NEW! :)

[miss_heard]

have you tried the SAS Emission Calculator? (it's quite cool :ok: )
http://sasems.port.se/

[The SSK]

Last two short-haul trips I did were Brussels-Frankfurt, great circle 304km, Michelin 401km, circuity 32%; Brussels-Geneva, great circle 530km, Michelin 724km, circuity 37%.

[StainesFS]

LHR -GLA simulator route based on flight tracker = 327nm (376 miles). RAC fastest route = 411 miles (9% extra). RAC shortest route = 395 miles (5% extra).

[CONF iture]

There is a lot of talk about 3litre per km per passenger aircraft coming onto the market
They are already here !
But it has a lot to see with the type of operation:

A-330
AMSTERDAM - VANCOUVER 4174 NM (Great Circle)
Fuel Burn 52000 Kg

Standard Airline ops at 270 pax
Fuel burn per passenger/100 km = 3.1 Liter

Standard Charter ops at 360 pax
Fuel burn per passenger/100 km = 2.3 Liter

Now I would not go in that comparison with cars as to find such highway does not look promising, even at 1.5 time the distance ...

[Strepsils]

I understand a car will likely have to travel further, but that is surely only an issue if you are comparing car v aircraft on a specific route.

If you are just comparing litres v km's it makes no difference if one does 1000km and one does 100,000km, you are still going to calculate the burn in litres/100km:confused:

[mm0wkj]

OK, here's a question for you.

757-200, 182 pax, full fuel load. whats the max range (transatlantic) West bound, UK-US.

[boredcounter]

My guess as follows,
APS 60,000kg
Traffic 20,000kg
Fuel 34,200kg
TTOM 114,200kg
Allowances:
Reserves: 5,000kg
C/T (un-useable) 500kg
Assumptions
Burn 3,500kg p/h
= Just under 8 ¼ hours flight time.
A 757-200 driver can answer you better though.
Bored

[Piltdown Man]

RANT ON:

It is only fair to compare like with like. Currently, the mass media have a hard-on about how our industry is polluting the world. From what I can establish, we are responsible for a measly 1.65% (but increasing) of the CO2 emissions in the UK where as the car is "only" responsible for 27% (also increasing). So when we compare fuel burns we must compare trip with trip, not just the mpg. Unfortunately, we haven't got the message out that shows just how efficient we really are in fuel, infrastructure and time.

In reality, if the government was really serious about our environment, they would be putting extortionate taxes on all fuels, household gas and electricity and subsidising the development of renewables and nuclear power, but Grasping Gordon is doing none of that. The seeds should be sown in peoples' imaginations that that if we are to reduce our carbon footprint we should all be walking or cycling, eating raw food and shivering in dark caves. However, they can still keep taking foreign holidays because stopping all aviation will do bugger all to reduce CO2 emissions.

RANT OFF

Regards, PM