vrus Posted October 11, 2005 Share Posted October 11, 2005 Planes get charged up when flying through clouds right? That's why they're earthed when they land. But in the case of mid-air refuelling, the planes can't be earthed. If there is a spark, then things can be lethal. How do they prevent this from happening ? Do they make the refuelling probe out of rubber or an insulator ? Link to comment Share on other sites More sharing options...
insane_alien Posted October 11, 2005 Share Posted October 11, 2005 the spark lasts maybe all of a millisecond so both planes will be equally charged(if there happens to be one for some absurd reason) by the time the fuel starts flowing so it won't be lethal in any way. planes are earthey on the ground because they make fantastic targets for lightning. it is also to prevent possible faulty wiring from electrocuting people and making sparks. on the ground it is earthed for exactly the same reason your toaster is, to prevent YOU getting a shock for faulty wiring. the thing about clods charging planes up is mostly myth. while it is possible for a plane to get a slight electrical charge it is dissipated to colliding air quite rapidly Link to comment Share on other sites More sharing options...
Douglas Posted October 11, 2005 Share Posted October 11, 2005 Do they make the refuelling probe out of rubber or an insulator ?My guess would be that the probes are made of metal such that when contact is made, they equalize the charge prior to pumping fuel. Link to comment Share on other sites More sharing options...
vrus Posted October 11, 2005 Author Share Posted October 11, 2005 the spark lasts maybe all of a millisecond so both planes will be equally charged(if there happens to be one for some absurd reason) by the time the fuel starts flowing so it won't be lethal in any way. planes are earthey on the ground because they make fantastic targets for lightning. it is also to prevent possible faulty wiring from electrocuting people and making sparks. on the ground it is earthed for exactly the same reason your toaster is' date=' to prevent YOU getting a shock for faulty wiring. the thing about clods charging planes up is mostly myth. while it is possible for a plane to get a slight electrical charge it is dissipated to colliding air quite rapidly[/quote'] I am no expert in static electricity . But I know that planes are insulated conductors. Their bodies are metal alloys (conductor) but when on earth, they are insulated by their rubber tires. So they would keep the charge without earthing it. But surely, planes get charged while flying ? Link to comment Share on other sites More sharing options...
5614 Posted October 11, 2005 Share Posted October 11, 2005 I like Douglas's idea in post #3 Link to comment Share on other sites More sharing options...
insane_alien Posted October 12, 2005 Share Posted October 12, 2005 a van de graaf generator is an insulated conductor as well and if i charge one up then turn it off and let is sit for a while it discharges within 2 hours. if i put a fan near it it can discharge in an hour and if the atmosphere is moist then it can discarge in an hour without the fan. it looses charge to the surrounding air and nothing is a perfect insulator Link to comment Share on other sites More sharing options...
Douglas Posted October 12, 2005 Share Posted October 12, 2005 it looses charge to the surrounding air and nothing is a perfect insulator I think it's more likely that it loses it's charge through it's own insulating material. Link to comment Share on other sites More sharing options...
insane_alien Posted October 13, 2005 Share Posted October 13, 2005 there was an experiment i did in highschool to show that charge can be lost to the surrounding air where we used some very thin insulating thread to hang a small sphere (resistance was on the order of tera-ohms) the sphere was then charged to 200V+/- 2V and left for 10 mins and we then measure the potential as 150V+/- 2 V the potential lost through the wire was something like 0.01V (teacher done calculations as we were too uneducated at that point) Link to comment Share on other sites More sharing options...
vrus Posted October 13, 2005 Author Share Posted October 13, 2005 Similar to what douglas said, I found out from one of my old books, that in these kind of situations, the two objects are connected by a copper wire first. So basically planes never get charged ? Well, well, well...! Is there any website that explains more about this ? Thnks. for the help ! Link to comment Share on other sites More sharing options...
Douglas Posted October 13, 2005 Share Posted October 13, 2005 there was an experiment i did in highschool to show that charge can be lost to the surrounding air where we used some very thin insulating thread to hang a small sphere (resistance was on the order of tera-ohms) the sphere was then charged to 200V+/- 2V and left for 10 mins and we then measure the potential as 150V+/- 2 V the potential lost through the wire was something like 0.01V (teacher done calculations as we were too uneducated at that point)Interesting, you must've had a super high impedance voltmeter to measure the voltage. Link to comment Share on other sites More sharing options...
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