# Tag Info

121

Several advantages: Wing structures are hollow and voluminous in order to provide structural rigidity against flutter and carry flight loads. This provides the space needed to store fuel. On a conventional aircraft, placing fuel tanks in the wings places the fuel mass very close to, or on, the center of lift. This dramatically reduces Cg shift during ...

88

It's for wing bending relief (for cantilevered wings). As the generated lift bends the wings upward, the weight of the fuel will counter that. As the plane loses weight in-flight due to burning fuel, so does the need for wing bending relief (less weight → less lift), that's why the wing tanks are the last to be used. For context, a Boeing 777-200ER can ...

81

I see what you're saying, but there's something you're overlooking in your logic. You're looking at an airplane sitting on the ground, where the wheels are near the fuselage and most of the wings are dead weight that creates strain on the structure. Think about one in flight. Now all the lift is coming from the wings, imagine the airplane suspended by ...

67

Pilot here (with Cessna 152 hours) as well as an engineer who made it most of the way to an Airframe and Powerplant technician license at one point in life. There are several reasons that conspire to produce 'unusable fuel': Fuel tanks on airplanes have complex shapes - they include baffles and other walls (with holes in them) to prevent oscillations from ...

48

Having all the payload of a plane concentrated at the fuselage creates a large bending load on the wings in order to support that weight. Storing fuel in the wings allows some of that weight to be placed at the same place where it's being supported, in the wings. Distributing the weight into the wings reduces the loads where the wings meet the fuselage.

47

Maybe This is dependent on the air frame and varies from plane to plane and not all planes have capability of moving fuel although most large planes do. The Concorde moved fuel all over the place from its 13 tanks to cool the nose cone as well as trim the aircraft. It was perhaps one of the most complex implementations of such a system and kept the flight ...

43

Your description of a self-sealing fuel tank remaining on fire when lit is the exact situation of the sealing mechanism failing. As soon as the tank is punctured, regardless of a fire or not, the rubber in the middle layer will react with the fuel and swell until the hole is reasonably obstructed. This both extinguishes the fire and seals the leak. Consider ...

41

Early aircraft designs used gravity feed to supply the engines with fuel. All those designs had their tanks located above the wing, and in biplanes in the center of the upper wing. The picture below (source) shows an Etrich Taube with the cylindric fuel tank mounted above the fuselage. The next application of overwing tanks were "Doppelreiter" fuel tanks (...

38

Which fuel tanks are used in order of priority in aircraft? What you're talking about, in large aircraft, is often referred to as the fuel burn schedule. Light aircraft generally do not have a fuel burn schedule though they may have have minimal requirements. The fuel burn schedule is dictated by the aircraft design and is thus different for different ...

35

Both the Typhoon and English Electric Lightning used over the wing fuel tanks as standard equipment for many years. There may have been others. English Electric Lightning Typhoon (with conforming tanks)

32

They are called drop tanks. When a drop tank is jettisoned, very likely it is not retrieved and reused. This is also the case with (sadly, discontinued) Space Shuttle external tank. Those tanks were not reused either. I am not talking about the rocket boosters. What happens to jettisoned fuel tanks? It depends on where they land. The tanks jettisoned in ...

31

Can a wide body airliner land with a full fuel tank? Yes! But it is safer to land an aircraft below its published MLW. Wikipedia has the relevant specifications for the B777 and the A330 Using the B777-200 as an example. Maximum take off weight: 545,000 lb / 247,200 kg Maximum landing weight: 445,000 lb / 201,840 kg So this particular aircraft may have ...

30

They can land safely with full tanks but they will need the gear checked before they can take off again. It's not unheard of, if you search for "overweight" on avherald you can see a list of them They will be marked as A38* or B77*. For example this flight landed with a weight of 523t while the max landing weight of that aircraft is 394t. If possible they ...

30

As a generic answer, not unusual. Besides personal objects like bucking bars, clecos, rags and such left in tanks, the biggest contamination source, from my experience working on a production line many many years ago, is "swarf". Swarf is aluminum drill shavings and mountains of it are created during assembly. You will also get wire cutoffs and other ...

28

In regions and weather conditions where this is likely to be a problem, other fuels are used instead of Jet-A. For example, Jet-B has a freezing point of -60C and is used during the winter in some parts of Russia and other very cold places. For information about fuel freezing in flight, see this previous question/answer.

28

No, it is perfectly normal to operate without any fuel in the center tank. Until your fuel load is over about 17,000 lbs, the center tank should be empty. That’s enough for about 2 hours of flying, plus reserves. If your simulator requires fuel in the center tank in order to start the engines, it isn’t accurately replicating the real aircraft.

28

(airliners.net) Be sure to turn on the appropriate pumps on the lower-left of the overhead panel. The APU can start without them via suction. Otherwise, it's a simulator problem. Also see: Why are fuel tanks in the wings filled first, and why are they used last?

27

Airplane wings are designed purely from aerodynamic and structural considerations. Supersonic fighters often have much thinner wings (and store fuel in the fuselage) because those are the requirements of supersonic flight. For subsonic (and transonic, which most modern airliners and business jets are -- over some parts of the wing the airflow is actually ...

27

No. The wing thickness is primarily dictated by structural demands. It has to provide an aerodynamic fairing for the wing spar. Making it thinner would drive up the mass of the structure inside. To simplify things, imagine the wing spar as an I-beam. It has two flanges which carry tension and compression loads, and a web between the flanges to transmit ...

27

added weight increases the structural load applied to the wings different gravitational forces and wing-bending between full and empty tanks result in repeating stresses shortening the aircraft life-span As a result of the effects of lift (and the deceasing need for it as the plane lightens) the reverse is actually true see here higher risk of ...

26

The conversation may have been about fuel pumps or fuel transfer valves but the flight attendant was probably told that as a simple explanation - it would not have been the real cause. Aircraft have multiple systems to pump fuel, transfer, and pipe it so no single failure will affect normal operation. For example, pumps have automatic bypass valves so ...

25

Consulting your handy POH (or one for a 172N that I Googled up) you'll find the fuel system diagram looks like the one below (click to enlarge - most high-wing gravity-fed fuel systems are similar). So there are a number of ways you could wind up with uneven fuel burn with this plumbing. The most common ones are: (Uncoordinated) Turns If you're flying lots ...

25

Yes fuel is moved around, and balance is indeed an issue. The A330 has trim tanks in the horizontal stabiliser, and so does the A380. Fuel can be stored there to balance the aircraft - without trim tanks the stabiliser would be set to produce lift to balance the plane, and this causes extra drag. In the A380 fuel transfer occurs automatically, unless a ...

25

In 747-100/200 aircraft, takeoff was accomplished tank-to-engine (meaning each engine was fed from it's corresponding main tank). After takeoff the fuel burn schedule called for center tank fuel to be used after takeoff until exhausted. This was done by turning on jettison/override pumps in the center tanks that put fuel from the center tank into the common ...

25

Fuel tanks take most of the space in aircraft wings, but not all. There are other things on wings too. They are ailerons, flaps, slats, air brakes. On most airliners, the engines are attached to the wings too, so their assembly takes up space. On the two aircraft of your interest, here are the pictures: A380 (its nickname is not jumbo, but superjumbo) ...

25

An incendiary bullet penetrating a self sealing tank won't necessarily cause a fire. Gasoline needs oxygen to burn. The Allies developed a self sealing bladder that not only plugged holes, but gradually collapsed as the fuel was used up, to suppress the mix of air and gasoline vapor that replaces the liquid fuel as the fuel is consumed and the level drops... ...

24

There are multiple ways for preventing fuel freezing in aircraft. In large aircraft, the fuel tanks have heating systems. Fuels with low freezing point, like Jet A-1 can be used. In really cold conditions (like Canada, Alska, Russia etc) Jet B (with freezing point -60$^{\circ}$) can be used, though this has higher flammability. The military equivalent of ...

21

In gaseous form, the amount of -- the mass of -- hydrogen you could store in the volume of aircraft fuel tanks would be negligible. In order to store enough mass of hydrogen, you'd have to store it liquified, which is how it's stored in rockets. In order for that to be useful, though, you'd have to have engines entirely redesigned in order to burn cryogenic ...

20

FAA Advisory Circular AC 103-7, Paragraph 19 has this to say: MAXIMUM FUEL CAPACITY OF A POWERED ULTRALIGHT VEHICLE. The maximum fuel capacity for a powered ultralight vehicle is 5 U.S. gallons. Any powered ultralight with fuel tank(s) exceeding this capacity is ineligible for operation as an ultralight vehicle. a. Determination of ...

19

It can happen very quickly. I don't have exact numbers, but an acquaintance had this happen in a Cessna 172 and the entire tank was emptied in just a few minutes - the amount of time it took to do one circuit of the pattern and land. The fuel cap was not in the filler neck on departure, and was hanging from the chain, banging against the wing. The moral of ...

Only top voted, non community-wiki answers of a minimum length are eligible