Why don't aircraft tyres explode?
Discussion
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Aircraft tyres are usually inflated with nitrogen or helium in order to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight. Dry nitrogen expands at the same rate as other dry atmospheric gases, but common compressed air sources may contain moisture, which increases the expansion rate with temperature. Aircraft tyres generally operate at high pressures, up to 200 psi (13.8 bar) for airliners, and even higher for business jets. Tests of airline aircraft tyres have shown that they are able to sustain pressures of maximum 800 psi (55.2 bar) before bursting. During the test the tires have to be filled with water, instead of helium or nitrogen which is the common content of aircraft tires, to prevent the test room being blown apart by the pressure when the tire bursts.
Aircraft tyres also include heat fuses, designed to melt at a certain temperature. Tyres often overheat if maximum braking is applied during a rejected take off or an emergency landing. The fuses provide a safer failure mode that prevents tyre explosions by deflating in a controlled manner, thus minimizing damage to aircraft and objects in the surrounding environment.
The main purpose of requiring that an inert gas, such as nitrogen, be used instead of air, for inflation of tyres on certain transport category aircraft is prompted by at least three cases in which the oxygen in air-filled tyres combined with volatile gases given off by a severely overheated tyre and exploded upon reaching autoignition temperature. The use of an inert gas for tyre inflation will eliminate the possibility of a tyre explosion
Aircraft tyres are usually inflated with nitrogen or helium in order to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight. Dry nitrogen expands at the same rate as other dry atmospheric gases, but common compressed air sources may contain moisture, which increases the expansion rate with temperature. Aircraft tyres generally operate at high pressures, up to 200 psi (13.8 bar) for airliners, and even higher for business jets. Tests of airline aircraft tyres have shown that they are able to sustain pressures of maximum 800 psi (55.2 bar) before bursting. During the test the tires have to be filled with water, instead of helium or nitrogen which is the common content of aircraft tires, to prevent the test room being blown apart by the pressure when the tire bursts.
Aircraft tyres also include heat fuses, designed to melt at a certain temperature. Tyres often overheat if maximum braking is applied during a rejected take off or an emergency landing. The fuses provide a safer failure mode that prevents tyre explosions by deflating in a controlled manner, thus minimizing damage to aircraft and objects in the surrounding environment.
The main purpose of requiring that an inert gas, such as nitrogen, be used instead of air, for inflation of tyres on certain transport category aircraft is prompted by at least three cases in which the oxygen in air-filled tyres combined with volatile gases given off by a severely overheated tyre and exploded upon reaching autoignition temperature. The use of an inert gas for tyre inflation will eliminate the possibility of a tyre explosion
Bushmaster said:
knight said:
They are inflated with nitrogen
Thank you for your input, that would be the perfect answer (to a different question). does that sound harsh? didn't mean to be harsh. I think it's too harsh.
Edited by Bushmaster on Sunday 22 March 11:51
Not filling them with anything that will undergo a phase change over the tyre's range of operating temperatures helps (ie, a dried gas not containing water vapour), and using an inert gas overcomes a small risk of explosion due to the combustion of gases out-gassed from overheated rubber, but I don't think it likely that tyres filled with ordinary compressed air would fail either.
Why does the op imagine that they should burst?
Why does the op imagine that they should burst?
lets say on the ground they are at 10bar (gauge) which is 11bar absolute but it is measured as 10 bar as you have 1 bar pushing in on the tyre
Now take the tyre into space where there is no pressure you have 11bar pressure gauge and 11bar absolute as you have zero pressure pushing inwards
So it has only gone up 1 bar or 14.5psi so not a huge amount
Now take the tyre into space where there is no pressure you have 11bar pressure gauge and 11bar absolute as you have zero pressure pushing inwards
So it has only gone up 1 bar or 14.5psi so not a huge amount
Bushmaster said:
Didn't think they would explode but that they would expand, which may cause issues. IIRC if a helium balloon is released into the atmosphere it will rise until it expands so much it pops, no?
The rubber carcase of any tyre is reinforced with very strong cords. These keep the tyre from expanding.Edited by Hammerwerfer on Sunday 22 March 13:58
knight said:
Bushmaster said:
knight said:
They are inflated with nitrogen
Thank you for your input, that would be the perfect answer (to a different question). does that sound harsh? didn't mean to be harsh. I think it's too harsh.
Edited by Bushmaster on Sunday 22 March 11:51
garyhun said:
Don't they employ dwarfs to sit in the undercarriage and let the air out after take off and then blow them back up again for landing?
Yes, special eskimo dwarves who can cope with the low temperature. They spend years training them up at altitude before they get their big break with an airline. Slightly o/t but in '96 I had the chance to do some skydives out of a Ilyushin 76 in Russia, the tyres were showing various layers of canvas through the rubber, like the rings in a tree trunk.. I asked the pilot if this was ok. He shrugged and said "Niet problemski", We, on the other hand were really glad we were not going to be around for the landings
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