airliner fuel tanks heating

[Guest WarpAir]

I can definatly remember watching an airbus documentry from Justplanes, where the pilot tranfers fuel between external tanks to to tanks closer to center of the plane, he did so cause as he said, fuel in the more outward tanks is warmer than fuel in the inner tanks. Cause fuel in wing tanks is warmer due to friction, compared to center tanks.

[Guest hfghfghfgh]

Don't expect they spent a lot of time on simulating fuel temperature or that they claim a lot of precision in this area.But since they had many real life 747 pilots advising them - they probably did just enough with the info they had.

Just this in response and then I will leave this topic since all that it was to say was said (and explained) - mostly by you.There is a physical law about energy conservation or something - meaning energy can't be destroyed it can only take different form.Regular car engine has 30% of heat efficiency, about 30% is transfer via radiator and the rest via exhaust. The first 30% when driving on flat surface is also transfered mostly to air by heating it and some het is generated by tyre friction also heating tyres and road surface. Some of the heat must also be generated into car's body (maybe up to one degree C if really speeding - 130mph)So jet engine also uses fuel kinetic energy, burning it into heat as this heat produces high pressure neccesary to form thrust. Jet exhaust power flow (airmass x EGT) is much lower than heat generated in jet combustion chamber and since plane doesn't have a radiator or tyres this difference is as seems generated into heat due to air friction/compression. However I think that most of this heat is transfered back to air due to isothermal heat transfer since aluminium has high thermal conductivity. LITTLE OF TOPIC BUT STILLPMDG 747 is highly detaileed add on aircraft but still it has many insufficiencys. Compare to its price they could do better. However I read that mostly all the natural behavior in MS FS 9/X is described with tables rather that with physical equation. Particularly is this seen when airplane under high speed stalls when you exced angle off attack and airflow cross wings is broken. At this point you just lose lift and altitude. This is however normal but if you have F16 flying at 500 kias at low altitude and suddenly strongly applly elevator upplane should gain altitude not lose it since there is too much inpact lift. Same thing happens when try to autorotate with helli. If you applly to much collective blades simply stop and you begin to rotate round your own vertical axle.

[michal 44]

LITTLE OF TOPIC BUT STILLPMDG 747 is highly detaileed add on aircraft but still it has many insufficiencys. Compare to its price they could do better. However I read that mostly all the natural behavior in MS FS 9/X is described with tables rather that with physical equation. Particularly is this seen when airplane under high speed stalls when you exced angle off attack and airflow cross wings is broken. At this point you just lose lift and altitude. This is however normal but if you have F16 flying at 500 kias at low altitude and suddenly strongly applly elevator upplane should gain altitude not lose it since there is too much inpact lift. Same thing happens when try to autorotate with helli. If you applly to much collective blades simply stop and you begin to rotate round your own vertical axle.

It is not well written and argued thought but perhaps it is better to leave it alone .. :(

[scott967 62]

If you go to some of the aviation sites and dig up the threads and reports on the BA 777 that lost both engines due to supposed fuel blockage/icing, there is quite a bit of theory and system design analysis concerning cold fuel tanks. Mainly 777 related of course, but also of general applicabilty as well.scott s..

[mebull 27]

Does airliners have fuel tanks heating?I know that PMDG manuals mentioned that b747 has temp probe in each tank and that EICAS warning message is created if fuel temp gets below -37

[tf51d 284]

Does anyone remember a certain 747 ( I forget the type and airline ) off the north east coast of U.S.A that exploded in mid-air? I believe the FAA determined that it was caused by faulty heater wiring in one of the center fuel tanks that ignited fuel fumes in a partially filled or empty tank. Based on that, it would seem the tanks had heaters, at least in the case of this particular 747. DISCLAIMER: I freely admit that I do not know anything about fuel heating other than what I have referred to above!Regards,Mel[/quoteThe MD-80 has a fuel heating switch on it (One for each engine), When turned on will go through a heating cycle then turn itself off, just like a car rear defroster would. Off is the normal position.

[KevinAu 441]

Does anyone remember a certain 747 ( I forget the type and airline ) off the north east coast of U.S.A that exploded in mid-air? I believe the FAA determined that it was caused by faulty heater wiring in one of the center fuel tanks that ignited fuel fumes in a partially filled or empty tank. Based on that, it would seem the tanks had heaters, at least in the case of this particular 747. DISCLAIMER: I freely admit that I do not know anything about fuel heating other than what I have referred to above!Regards,Mel

That was TWA 800. It was caused by faulty wiring to the center tank fuel pumps.

[mgh 89]

Does anyone remember a certain 747 ( I forget the type and airline ) off the north east coast of U.S.A that exploded in mid-air? I believe the FAA determined that it was caused by faulty heater wiring in one of the center fuel tanks that ignited fuel fumes in a partially filled or empty tank. Based on that, it would seem the tanks had heaters, at least in the case of this particular 747. DISCLAIMER: I freely admit that I do not know anything about fuel heating other than what I have referred to above!Regards,Mel

If you are refering to the 737-131 on TWA Flight 800 on 17 July 1996 where the centre wing tank (CWT) exploded, the NTSB concluded that: The source of ignition energy for the explosion could not be determined with certainty, but, of the sources evaluated by the investigation, the most likely was a short circuit outside of the CWT that allowed excessive voltage to enter it through electrical wiring associated with the fuel quantity indication system.During its investigation, the NTSB considered a wide range of possible causes. These did not include a fuel heating system because the aircraft wasn't fitted with such a system.http://www.ntsb.gov/Publictn/2000/AAR0003.pdf

[mebull 27]

Thanks to all for correcting 'my' faulty wiring.Sincerely,Melhttp://en.wikipedia.org/wiki/TWA_Flight_800