Alleged jet fuel capacities/efficiencies

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Alleged jet fuel capacities/efficiencies

Postby scud on February 27th, 2018, 10:38 pm

There’re a few videos now swirling around YT concerning aircraft and the seemingly preposterous claimed fuel capacity figures.

Let’s take a cursory look at the airbus A380 as an example https://en.wikipedia.org/wiki/Airbus_A380
with tanks that are capable of holding a said 320,000 liters of fuel. Hmm, that’s quite a bit isn’t it? Yes, certainly when you consider that this image shows an underground storage tank, 20,000 liters short of those of the airbus..
Image
http://spelproducts.co.uk/products/tank ... und-tanks/

Crikey...what a whopper! Ok, so where does the A380 carry this gigantic quantity of flammable liquid? Turns out that almost all of it is held within the wings (some 118 tons in each) and the remainder in the tail plane (a central tank is apparently absent).
Agreed, the wings are huge with an overall span of 80m but then I think that you will also agree that the volume cannot be taken up in its entirety with fuel because there is an enormous landing gear well, flaps, spoilers, engine support pylons, hydraulics and a multitude of structural beams and spars.
Image

Volume aside, I find it difficult to make sense of the colossal weight essentially bolted to the side of an aluminium fuselage amplified by the tremendous leverage created by the length. 118 tons in fuel alone is the equivalent to just under 20 (on a single wing) of the largest specimens recorded of this magnificent beast.. Image
https://en.wikipedia.org/wiki/African_elephant

There’s no way, is there?

Observationally too, one might consider that the overall behaviour of these modern marvels of transport doesn’t seem to stack up given the stories about fuel load. When we roar down the runway, liftoff and climb towards cruising altitude we know and expect the engines to sound stressed. Then, as soon as we approach our set altitude the plane levels and the engines simmer down to a soporific purr where audio levels, plane attitude and wing geometry will seemingly remain exactly the same until we begin to hone in on our destination and start the descent.
So ok. Were onboard our A380 laden with 320,000 liters of jet fuel and have just settled down with a nice G&T at 35,000 feet, leaving London Heathrow for Perth Australia. Do we notice anything different about the aircraft as we make our way over the English channel than when we are approaching the West coast of Oz? I’d suggest that no, we don’t and even though ‘I’m not a scientist’ (or pilot) it’s quite absurd to think that our mode of transport will soar through the air at the same speed, at the same angle of attack, at the same altitude with the same level of trim in laden form as unladen with the exact same level of 'oomph' from the engines (which I'd say is what we hear).

Well, this of course brings into question the entire logistics of fuel delivery and storage at airports. I’ve so far only skimmed this subject but the quantities involved would seem to be pretty implausible. Just ten long haul A380 departures would require this... Image
(Olympic swimming pool 50 x 25 x 2.5m deep = 3125 cubic meters = 3,125,000 liters / 320,000 = 9.76).


I don’t really want to elaborate much further at the moment because of course others are theorizing that gas turbine engines work on a completely different principal than we’re told and consume no liquid fuel at all (all seem to be flat Earth types but nonetheless I’ll leave a couple of links, should you be interested).
I personally don’t think that this is the case at the moment and am erring on the side of far greater fuel efficiency than is publicized simply to justify the cost of flying to you and I. Also, specified wing volumes, detailed dimensions or indeed photographs of actual fuel tanks seem to be conspicuously absent to make a clear cut case in our favour.

Sorry chaps, not much time at the mo’ so I’ll leave it at that and look forward to your thoughts.

Here’s a couple of vids...

https://www.youtube.com/watch?v=R4KhvDzSfMQ

https://www.youtube.com/watch?v=t1OlYtIBpJ0
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Re: In Plane Sight.

Postby Penelope on February 28th, 2018, 3:24 am

Interesting question scud. What's that song "It's my story, and I'm sticking to it" ? Appears they're publishing fairly equivalent fuel capacity for the next size planes:
Airbus A380 you mention fuel capacity is 320,000 Liters
--Boeing 747-400 30% smaller fuel capacity 216,640 Liters noted as an efficient airframe
--Boeing 747-8 passenger floor space is 40% less, fuel capacity 238,610 Liters

LAX :
http://www.elsegundo.org/civicax/fileba ... obID=18094
In 1994 Total departing aircraft fuel capacity 7.24 million gal, but actual demand (fuel dispensed) 4.1 million gallons.

http://www.aviationpros.com/article/102 ... nd-profits 2011 STILL 4 million gallons???
Upon entrance to the LAXFUEL facility through a crash-rated gate, the first impression is — simply put — a little intimidating. Several large storage tanks accent the skyline and line the grounds, interconnected through an intricate system of pipelines. Aircraft Service International Group manages the facility, which it has done since 1986. With substantial development in the past 25 years, the facility is the largest operation of its type in the country, supplying more than four million gallons of Jet A to airlines each day. . .

The facility currently serves approximately 75 to 80 airlines at the airport. It features 15 large storage tanks and a state-of-the-art filtration system as well as 18 pumps that dispense fuel at a rate of 1200 gallons per minute. It has an on-airport capacity of more than 600,000 barrels of fuel. It is fed by four pipelines from a variety of fuel supply sources. Three off-airport storage locations provide a capacity of 1.5 million barrels. “We have about 20 days of fuel supply capacity with on-airport and off-airport storage,” according to Jim Moses, LAXFUEL’s facility manager.

A barrel is 42 gallons

LAX is difficult to judge by fuel storage because El Segundo is a refining center and it makes sense to pipe in supplies from outside.
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Re: In Plane Sight.

Postby Altair on February 28th, 2018, 12:46 pm

Indeed, it would be an engineering miracle to build a plane's wings so that they would perform as a 100% fuel-tight container, and to remain this way for the +20 years of useful life of an airplane, while subject to flexing, vibrations, pressure changes, metal fatigue and varied mechanical stress forces. Even more when the possibilities of performing maintenance inside of the tanks are ridiculous, as that would require completely emptying and ventilating them. I'm quite of an aviation fan, and though there have been many instances of fuel leaks, I never heard about a plane rendered unusable by a crack or loosening in the wing junctures, which would be the thing to expect. In light aircraft, fuel is contained in plastic tanks inside the wings, but that's not an option in sizable airlines, and for what's seen in the video, the interior is bare metal.
Anyway, any alternative explanation as for turbines working, is also hard to believe.
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Re: In Plane Sight.

Postby scud on February 28th, 2018, 9:19 pm

Another point that I hadn’t previously considered.

Kerosene (jet fuel) freezes at -40 degrees C https://en.wikipedia.org/wiki/Kerosene but the average ambient temp’ at 35,000 feet is said to be in the region of -57 degrees C... http://www.traveller.com.au/why-planes- ... hts-guxhc9

I dunno. I too am an aviation enthusiast but I’ve not heard of a ‘fuel tank heating system’ to keep the stuff from solidifying over say an 18 hour stretch exposed to these temperatures.
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Re: In Plane Sight.

Postby Penelope on March 1st, 2018, 8:37 am

Scud, I got interested in the issues you bring up; I would never have thought of them. Here's what I found.

Jet Fuel Anti-Icing Additive - Dow Chemical
https://www.dow.com/oxysolvents/app/oth_jet.htm
‎DOW Oxygenated Solvents. Methyl CARBITOL** Solvent is used as an additive in jet fuels to prevent ice buildup in fuel lines and to inhibit growth of bacteria in fuel tanks of primarily military and private aircraft


Doesn't say commercial planes though.

http://www.airliners.net/forum/viewtopic.php?t=1360257 Click on the image to see 4 tanks per wing plus the trim tank.

Would each separate tank have to be isolated airtight from the others for the inerting gas to be dependably of the correct ratio? I guess plastic, cuz aluminum would corrode, for immediate fuel contamination. Or maybe CFRP composite.
This aircraft makes unprecedented use of CFRP (Carbon Fibre Reinforced Plastic), including on the leading edge of the wing, and a CFRP composite central wing box.

1 liter = 1 decimeter squared or 1/1000th of a meter squared
1,000 liters = 1 meter squared
320,000 liters = 320 square meters required
Is there space for 320 square meters of tanks, what do you think?

Wait a minute. Don't the tanks have to fit between the wing's support ribs? And how far apart are the ribs? Either that or be less wide. Width of the exterior wing is more than two stories.

https://www.youtube.com/watch?v=PF6ZuBDlNjY At 11:24 there's a slight indication of where the tanks or at least the fuel lines are. Looks like the tanks sit atop the ribs?? So the ribs just brace the bottom of the wing? I'm confused.

Didja notice in my lst post that LAX says its daily fuel use of 4.1 million gallons (15,520,188 liters) is UNCHANGED from 1994 to 2011? I thought that was a little strange. As of 2013 it was 3d busiest airport in the world.
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Re: In Plane Sight.

Postby Altair on March 1st, 2018, 9:05 am

In any case, if the fuel is in plastic containers... why on earth does the girl in the video get into a wing for sealing the joints with a spray? Even more, how would they fit the containers into the wing once it is already mounted?

About the freezing point issue, I've found this link: https://aviation.stackexchange.com/ques ... -in-flight

But after reading it, it seems that somehow they leave the freezing issue to chance. Something like it takes much time for that amount of fuel to freeze. I can undertand that line of reasoning for short haul flights, but what about transatlantic ones that might last more than 12 hours? Even more when theoretically, the amount of fuel would be decreasing and be very small towards the end of the flight. Also, it's ridiculous when they say that crew can choose a route with higher temperatures :blink: .

This is a calculator of atmospheric conditions. For 40000 ft, a quite normal fliying altitude, it gives -56ºC. Even taking into account all factors mentioned in the above answer (air friction, etc), thats 16ºC below freezing point.

https://www.digitaldutch.com/atmoscalc/
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Re: In Plane Sight.

Postby Penelope on March 1st, 2018, 11:46 pm

ooops . . . where I said
1 liter = 1 decimeter squared or 1/1000th of a meter squared
1,000 liters = 1 meter squared
320,000 liters = 320 square meters required
Is there space for 320 square meters of tanks, what do you think?


I meant 1 liter = 1 decimeter cubed or 1/1000th of a meter cubed, etc
ending with
Is there space for 320 cubic meters of tanks?
--
Altair, do you really think they'd risk expensive planes by not preventing icing of the fuel?

https://www.shell.com/business-customer ... craft.html
"Shell AeroJet uses Fuel System Icing Inhibitor (FSII), an approved additive that dramatically lowers the freezing point of water, thus preventing ice formation." This is available in a pressurized can and may have been what you saw being sprayed.

The following is just a commenter on CR4.globalspec.com but I find him credible:
"Re: Antifreeze for Jet Fuel" by Keith E Bowers on 06/05/2009 6:40 PM (score 2)
The subject chemical is NOT an antifreeze for jet fuel, but inhibits the formation of ice crystals in the fuel. Those solid particles would plug fuel filters and the very fine metering passages in the fuel control and vaporization equipment. It has been used for at least 5 decades now in ALL commercial jet fuels and all JP-4 and JP-5 military fuels as well. It is often added to the fuel right at the aircraft wing to ensure its presence, since any bulk water in the fuel will 'wash out' all the anti-icing inhibitor 'AII' as it is often called. Several aircraft losses, and numerous engine flame-outs were atributed to fuel icing before use of fuel icing inhibitors became mandatory for commercial aviation flights,and then the Military also required it.
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Re: In Plane Sight.

Postby pov603 on March 2nd, 2018, 9:29 am

Whilst I don't doubt the fuel carrying capacity of aircraft such as the A380, this did catch my eye!...

http://www.bbc.com/news/world-europe-43239331

One system Mr Putin described included a "low-flying, difficult-to-spot cruise missile... with a practically unlimited range and an unpredictable flight path, which can bypass lines of interception and is invincible in the face of all existing and future systems of both missile defence and air defence".


Wonder why we don't ask the Ru-skies the sell them directly, if they want to effect world domination!...

What a load of twaddle... :puke:
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Re: In Plane Sight.

Postby Penelope on March 2nd, 2018, 8:58 pm

Thank you Altair for the excellent source https://aviation.stackexchange.com/ques ... -in-flight

by Altair » March 1st, 2018, 12:05 am
Also, it's ridiculous when they say that crew can choose a route with higher temperatures.


I think I understand your reservation. It sounds so ad hoc. It would be decided at the operator's end: There are several customary flight paths between specific airports. In choosing among them he would factor in the anti-icing properties of the type of aircraft and the customary weather. The crew would alter the flight plan mid-air only due to emergency or serious weather change.

At your excellent aviation site I think KeithS has given us perhaps the most important factor:

In addition to the excellent points, I'd mention outside air pressure. Yes, it's cold at high altitudes, but not like it being cold at sea level; it's cold because there is an insufficient amount of air to conduct heat into the object being measured (or doing the measuring). By the same token, that air isn't conducting heat away from the aircraft as fast as cold air at sea level would be. So while the wings are in -40*C air, they aren't equalizing to that temperature by conduction as fast as they would be if parked at McMurdo Station Antarctica. – KeithS Oct 1 '15


However, note that it somewhat contradicts the argument that the friction of air passing over the wings warms them & the fuel within: If the wings encounter insufficient cold air particles to promptly freeze the contents, then it's unlikely this quantity of particles creates suffient friction for much heating.
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Re: In Plane Sight.

Postby scud on March 2nd, 2018, 10:44 pm

Boeing 777 central fuel tank (please double check the maths).

Image

If we take the outside diameter of the fuselage of the 777 at the given 20 foot 2 inches (6.14 meters) and the maximum given width of the wing at 42 foot 8 inches (13 meters) the calculated volume of this cylinder is 384.92 cubic meters or 384,920 liters.

Again it’s just diagrammatic (no photographs of what could be taken to be actual ‘fuel tanks’ seem to exist) nonetheless, Boeing themselves claim that the centre tank of the 777 has a capacity of 103,290 liters or just over one quarter of the above calculated fuselage section. http://studylib.net/doc/18610379/777---boeing (I would much appreciate it if somebody more tech savvy than I could reproduce this image here).
Hmm...or indeed one third the volume of our giant subterranean tank shown in the opener.

This really doesn’t look right to me. I can only estimate but the diagram would seem to indicate dimensions at most of 6 meters across by 1.5 meters deep by say 5 meters front to back? Let’s say that this tank doesn’t have any internal obstructions (a perfect void) then maximum capacity would be just 45,000 liters. In other words it would obviously have to be more than double what the Boeing diagram suggests.

Point aside, are the wing tanks really as thick as Boeing indicate? Don’t forget the landing gear chaps.

Image

For reference the General Electric GE90 engine has an external diameter of 3.25 meters.. https://en.wikipedia.org/wiki/General_Electric_GE90

Penelope and Altair, thank you very much for your contributions. As with the electricity supply thread, this was not an original observation and I do take on board the fact that it seems primarily pushed by those who don’t think that Earth is spherical and must therefore be by default, flat. That aside though, I can’t get out of my head the old mantra that we’ve all heard 6 gazillion times...’jet fuel doesn’t melt steel’. Two for the price of one?
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Re: In Plane Sight.

Postby Flabbergasted on March 3rd, 2018, 1:05 am

scud wrote:I would much appreciate it if somebody more tech savvy than I could reproduce this image here.

Is this the image you wanted?
Image
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Re: In Plane Sight.

Postby Penelope on March 3rd, 2018, 7:17 am

Regarding protecting fuel from freezing, I think we can pretty much bury that concern. Since there's not too much info available on Airbus's A380 regarding its fuel system I researched their A320:

https://www.youtube.com/watch?v=Cy3HnP6nf0c Fuel System of A320 explained by "Capt Joe" Much specific info. The accepted temperature range of the fuel is stated as "-43 C to +45 C. The A320 has a fuel-to-oil heat exchanger. So maybe this is a part of the A380's temperature management, too.

Searching for "A380 heat exchanger" I got a couple hits:
In 2003 HS-Nauka, a Moscow-based joint venture of Hamilton Sundstrand, had brazed the first heat exchanger cores for the system.
In 2009 Meggit was supplying to the A380 an airframe mounted hydraulic cooler heat exchanger.

For a general view of the construction of large craft fuel tanks, although this one's not identified
https://www.youtube.com/watch?v=giEMzfmQoqs

Scud, why did you switch your analysis from Airbus A380 to Boeing 777?
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Re: In Plane Sight.

Postby scud on March 3rd, 2018, 6:52 pm

Thank you very much Flabbergasted, that’s the one.

Scud, why did you switch your analysis from Airbus A380 to Boeing 777?


I think that the fuel capacity question applies to all gas turbine powered aircraft. The mind boggling, given consumption figures of these engines therefore the amount they have to carry for specified range. The colossal weight of the fuel and of course the volume that this would necessitate.

Let’s have a look at some military aircraft...
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Re: In Plane Sight.

Postby Penelope on March 6th, 2018, 12:10 am

Here’s a couple of vids...

https://www.youtube.com/watch?v=R4KhvDzSfMQ

https://www.youtube.com/watch?v=t1OlYtIBpJ0

Scud, these 2 vids are dumb. Are there any more convincing ones? In the first one, narrator mocks the method of checking to see if fuel tanks are air & water tight. At the wing factory they fill a tank with compressed air and check on the outside wall whether air is leaking through by spraying it with a viscous liquid that will bubble wherever there's any air escaping. No indication of how long the compressed air will remain so that they can check the tank for falling pressure. Yet he says the test is phoney, evidence that no fuel will go into the tanks, since there's an alternative method of powering aircraft. All because he finds unconvincing one tiny incomplete demonstration of how tanks are tested.

In the second one he shows us a picture in a book of an aircraft wing under construction in a factory. He points to a slice of the wing, obviously incomplete and alleges it's the completed wing. Wings are, of course, made up of reinforced layers. There's a rib-reinforced bottom layer, a curved composite top layer and electronics to control & monitor engines, flaps & ailerons. And more. Yet this abusive man is telling us that this little nothing is a complete wing cross-section? I know wings look thin in the air. The only cure for this is go to an airport and get as close as you can to them.

Sorry. It just annoys me to hear such a dumbkoff try to manipulate people with no-content mockery.
It's very much like flat earth.

Because you don't perfectly understand how a globe-earth system works, their flat earth model must be correct-- although they've presented no model showing how it would explain our perceptions of moon & sun, or even the seasons.

Think of all the things you don't understand about aircraft. You see? They must operate by some other method. Sorry, of course it's worth questioning by looking for space sufficient to store the quantities of fuel they claim are used.
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Re: In Plane Sight.

Postby Penelope on March 6th, 2018, 5:29 am

by scud » March 2nd, 2018, 1:44 pm
This really doesn’t look right to me. I can only estimate but the diagram would seem to indicate dimensions at most of 6 meters across by 1.5 meters deep by say 5 meters front to back? Let’s say that this tank doesn’t have any internal obstructions (a perfect void) then maximum capacity would be just 45,000 liters. In other words it would obviously have to be more than double what the Boeing diagram suggests.



Tanks would usually have pumps, temperature probes, and partitions to keep the fuel from moving too much when the plane banks, which occupy little space.

The math on the center tank: You have 6 meters across by 5 meters front to back, and 1.5 meters depth. I think we should consider the depth 2 meters (when you compare it to the front to back dimension in the tank illustration.) That would give us 6 x 5 x 2 = 60 sq m.

Total indicated liters in the tanks is 181,270 liters, so we need 181.3 cubic meters of tank space.

Compare the indicated 38,990 liters in the wingtanks to the indicated 103,290 in the center tank. Clearly the center tank is intended to be larger than the wing tanks. So I think they intended to include more of the combined tanks as "center tank". To make the tanks proportional to their indicated contents, we should include as "center tank" all the way to one crossline on the right wing, and two crosslines on the left wing. Maybe those lines just indicate partitions?

However, let's leave the measurement as it is (at 60 sq meters). For ease of measurement I can now measure all the previously excluded tank area as a proportion of wing area. I happen to know that the combined wing area is 436.8 sq meters, 218.4 sq meters per wing.

Looking at the right wing, I'd say the unmeasured tank on that side occupies 53% of the wing's area, 115.752 sq m x an average thickness of .5 m = 57.87 cubic meters + 57.87 cubic m for the other wing tank + the 60 cubic meters alotted for the center tank = 175.7 cubic meters.

Given that our whole exercise was approximation I'm satisfied that there's enough space for fuel in this plane. What do you think? Are there other arguments indicating that aircraft are unlikely to be using the jet fuel that we are told about?

Source for the area of the wings: https://www.airlines-inform.com/commerc ... 7-200.html
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