Can anyone tell me how aircraft such as jet fighters and stunt planes design the fuel tank vent system to prevent fuel leaking through the vents when performing aerobatics, 360 flips and complex maneuvers? Surely jet fighters don't just let it leak out?
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1$\begingroup$ Why are fuel tanks vented? Is my car tank vented too? $\endgroup$– user7241Commented Dec 26, 2017 at 20:03
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1$\begingroup$ @jjack -- the tank vents allow air to come into the tank to replace the fuel that's pulled out by the fuel pump. $\endgroup$– Pete BeckerCommented Dec 26, 2017 at 20:10
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1$\begingroup$ @PeteBecker Why is this done? $\endgroup$– user7241Commented Dec 26, 2017 at 20:11
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1$\begingroup$ Vents are also used to remove fuel vapours and prevent the fuel tank from pressurising in cars the vent typically runs to a charcoal canister to reclaim fuel. $\endgroup$– Chris JamesCommented Dec 26, 2017 at 20:14
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1$\begingroup$ @jjack because otherwise the vacuum that developed in the tank would suck the fuel back into the tank with more force than the fuel pump sucked it out, the pump would stop pumping, and the engine would stop engineing. And yes, your car has a venting system too. $\endgroup$– hobbsCommented Dec 27, 2017 at 6:48
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1 Answer
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There are 3 common solutions,
1) do nothing, unless the airplane is flown for an extended period of time inverted, there will be no appreciable vacuum created from fuel use and the vent is so small that there will not be appreciable fuel loss.
2) point the vent into the slipstream giving a ram air effect.
3) use two vent tubes (can be mounted either top & bottom or same side), at least one extends to opposite side of the tank.
This picture is for RC or drone aircraft but the same principle is used for full scale aircraft.
answered Dec 26, 2017 at 22:46