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ULH flights burn much more fuel

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ULH flights burn much more fuel

Old 9th Jan 2017, 23:36
  #21 (permalink)  

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Which type, if I may ask?
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Old 9th Jan 2017, 23:41
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I did a request to analyze the hourly fuel burns for the Global Express using s common flight planning engine. For each additional hour, the overall fuel burn declined, as expected, the "fixed cost" of start, taxi and climb was spread over loner time. At around the seven hour mark, the unexpected happened, the hourly burn increased.

As the added fuel equaling less distance, yes, I've seen, but it wasn't the fuel it was the added drag of external tanks. The early A-10s were ferried with three tanks, then some bright spark, put two ranks, widely spread on the pylons reduced drag and the less weight equaled slightly better range with less fuel.
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Old 9th Jan 2017, 23:47
  #23 (permalink)  
 
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Originally Posted by FlightDetent View Post
Which type, if I may ask?
A380 mate which operates the 2 flights I've used
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Old 9th Jan 2017, 23:54
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Funnily enough I was talking about this the other day. On some (extremely rough) calculations on the DXB-AKL vs DXB-SYD-AKL

DXB-AKL- 231T
DXB-SYD-AKL 225T

Like I said, rough calculations, but the 6T of fuel saved is roughly 30 minutes of flying.

Perhaps someone could give more accurate figures
And stopping off in Sydney is an excellent idea anyway, nice place to be, no need to hurry on by
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Old 10th Jan 2017, 00:20
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But once you add the landing fees, handling fees, extra crew required over the year to operate one additional stop, hotels, per diems, catering and delays, 6 tonnes * US$ 550 is negligible.

Expect around US$ 30,000 to turn around a 380 in a major airport and once you include the extra crew salaries, per diems and hotel bills you are closer to $ 60,000.

The flight plans have a formula. On a 13 hour flight for every extra tonne of fuel / load you carry you burn around 500 KGS extra on the 380.
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Old 10th Jan 2017, 01:19
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Same on the B777. Routes I use to fly between 12-14 hours and the delta burn for 1 tonne was 450-500 kgs.
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Old 10th Jan 2017, 05:19
  #27 (permalink)  
 
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How the money men figure it.

http://catsr.ite.gmu.edu/SYST660/air...ciers___v1.pdf
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Old 10th Jan 2017, 08:13
  #28 (permalink)  
 
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Originally Posted by DaveReidUK View Post
No, as a simple thought experiment will show.

Hopefully I can leave that to the interested reader.
D'oh...

Tunnel vision or something on my part. Missing that was embarrassing.
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Old 10th Jan 2017, 11:28
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A 747 guru once told me that the theoretical range limit of a 747 was 29 hours (close to the 33 hours quoted above for 3%/hr). If you had unlimited fuel capacity, the longest you could fly for was 29 hours. Any fuel added above that would be burned by the time you reached 29 hours. (For G&D's son's benefit, flying 29 hours in a 747 would require "infinity fuel")...

It would be interesting if someone could post the kg cost of carriage for a 787-9 or A350 at max range (full tanks) and MTOW. I'm guessing it would be at least 500 kg per tonne but these aircraft are obviously more efficient than the 747.

I recall once reading the cost of carriage for a Saturn V rocket. I don't recall the figure but it was so close to 100% the fact that it could actually escape the planet is staggering. If Earth was a few percent larger than it is we would never have made it to the moon. It would have become theoretically impossible from a single launch. Of course an orbital re-fuelling stop enroute would still have been a possibility.

Which begs an amusing question. If Qantas wanted to fly Sydney to London direct (probably around 21-22 hours), what would be the cost of launching an airborne refuelling tanker out of Singapore en-route (Air Force 1 style)?

I'm sure someone's suggested it before, just prior to being laughed out of the bar...

Last edited by Derfred; 10th Jan 2017 at 12:02.
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Old 10th Jan 2017, 12:52
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Originally Posted by Derfred View Post
Which begs an amusing question. If Qantas wanted to fly Sydney to London direct (probably around 21-22 hours), what would be the cost of launching an airborne refuelling tanker out of Singapore en-route (Air Force 1 style)?
You need to think more laterally than that.

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Old 10th Jan 2017, 12:57
  #31 (permalink)  

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Originally Posted by OMAAbound
A380 mate which operates the 2 flights I've used
Thanks, maybe the FCOM provides similar tables to these for A333?

PER-FPL-FLP-QFP Quick Determination of flight planning.



With max capacity of 76.561 kg, let's take away -261 of taxi out fuel and -5300 leftover after landing (my best educated guess)
= 71000 kg left to burn.

then


Reading: at most efficient FL410 (with stepped climb) the aircraft would burn 68928 kg over 1326' stage of 6200 NM air-distance. Any 1000+ kg in mass (payload, fuel) would increase fuel required by 389 kg (a.k.a. burning 38,9 per cent of any fuel tankered).

in comparison, half distance


burns 32446 kilograms.

Conclusion: 2x 32446 kg = 64.892 kg for equivalent air distance, plus 500 kg on ground for the half-way turnaround (reversers, taxi in, APU, taxi out) -> (71000/64892 - 1)*100 => 5,4% disadvantage without the stop.

The above pencil excercise is based on LW 140t (table definition), rather emptish?
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Old 10th Jan 2017, 13:06
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I'm sure someone's suggested it before
Sure have, not only suggested, but trialled, pre WWII mail runs across the Atlantic by Imperial Airways using Empire flying boats, and British South American Airways using Lancasters London to Bermuda non-stop. Nothing new under the sun.
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Old 10th Jan 2017, 13:17
  #33 (permalink)  
 
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OMAAbound

Just for interest sake do you have a burn DXB-PER for the A380.
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Old 10th Jan 2017, 13:40
  #34 (permalink)  
 
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@B772, 132T on a 10.15 sector, give or take.
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Old 10th Jan 2017, 14:50
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Originally Posted by B772 View Post
OMAAbound

Just for interest sake do you have a burn DXB-PER for the A380.
I'd go slightly higher at around 139T on 10hr30.
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Old 10th Jan 2017, 15:56
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Flight plan shows 129.5t, flight time 10.03 for DXB to PER. Carrying 56.4t revenue. And as Monach said 132.9 when winds make it 10.15. Both flights carrying 25.7t fuel for ALTN YPAD.
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Old 10th Jan 2017, 16:57
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Thanks Don, my very rough calculations were based on the block times used by EK.

How about the DXB-AKL/DXB-SYD-AKL calculations I made earlier on in the thread?
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Old 10th Jan 2017, 20:37
  #38 (permalink)  
 
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OMAA, it's 198t direct, TOW 13t below max. 207.9t via Syd, TOW out of DXB 20t below max, but carrying more revenue. Total flight time is only 1hr 30min different to direct SYD, so probably not the best example.
AKL via MEL takes 14 min longer than direct, and total burn is 202.1t. It was carrying more revenue out of DXB.

Last edited by donpizmeov; 10th Jan 2017 at 20:48.
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