Fuel Temperature Question

[rgamurot 1]

I was just wondering if the fuel temperature on the B744 really drops as quickly as it does in FS. Shouldn't it take several hours for 200 tonnes of fuel to cool to -8C?Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

[G-CIVA 62]

Ryan,I agree...the temp of the fuel seems to be directly linked to the TAT displayed above the primary engine indications at the top of the EICAS Page.I dont know if the MFS platform allows the PMDG model to simulate a potential 'cold soak' scenario.But I agree...if you set off say from KLAX at a TAT of perhaps 25C across the pacific by the time you are at your initial CRZ Alt the temp of what could be up to 165T of gas seems to mirror the TAT...I'm sure it would take at least a little longer for the fuel temp to drop..& I guess fuel in different sections of the real a/c would change temp at different rates (wings, belly & stab).Maybe it is just as simple as a limitation of the MFS platform & by mirroring the TAT at least we see a change in fuel temp?

[craig_read 43]

Take a look at this guyshttp://www.boeing.com/commercial/aeromagaz...olar_story.htmlThis part helps you a lot I think.. "It takes approximately 15 min to 1 hr for a change in TAT to affect the fuel temperature. The rate of cooling of the fuel is approximately 3

[Guest A32X]

I would think using PMDG's philosophy that Fuel Temperature shouldn't yet be displayed (if it's not accurate to real life...)Paul

[craig_read 43]

Well yes I see your point... but on the other hand even if it wasn't modelled exactly.. it would have to be present for the display to look authentic..CheersCraig

[G-CIVA 62]

Craig,Thanks for the info...very enlightening. I believe you last statement must be correct...it has to be modelled to a certain degree iot make that part of the programme give us an authentic EICAS Display.Just setting up for SFO - HKG as SQ001...not to the RW dep time but with a planned TO at around 1700zish I'll be on the ground in HKG for around 0700z tomorrow morning!!!!I'll have a look at the Fuel Temp along the way...but the WX on my PAC track is gonna give a slightly higher temp (than SAT) at CRZ levels.Ryan,I'll be passing approx 1500nm N of PHNL at around 1900-1930z...I guess thats approx 0900-0930L in your neck of the woods - I'll give you a wave on the way past!!!!:-jumpy

[rgamurot 1]

I don't quite think it's a bug any more because a new jet I bought recently does simulate the fuel slowly cooling. That's what brought up my question. It was also recently released so maybe PMDG will model fuel cooling time in the 747X. Then again, there is still the odd chance that this is how the gauge works in real life. Maybe the thermometer is in a different part of the tank or fuel system.Steve, Have fun on your flight. I have yet to try a full Trans-Pacific flight. I've only been brave enough to fly from PHNL to RJBB. I'll be on the lookout for SQ001!Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

[G-CIVA 62]

Ryan,Here is my route & some stats so far...the fuel temp lagged behind the TAT by about 1 deg C all the way through the climb...fuel temp is now the same as my TAT.Here is the route I am using today:KSFO (RWY 28R, SID SFO8)ALCOA CEPAS COBAD 42N40 45N50 47N60 48N70 47E80 44E70 41E60 34E50 UKATA BIXAK DELTA ONC G581 BISIS R583 APU W4 HLG A1 ELATO (STAR ELATO 1B, RWYS 25L/R)INIT CRZ LVL FL300STEP 2000COST INDEX 125ZFW 225500 KGSBLOCK FUEL 171600 KGSTAXI WT 171500 KGSATOW 396600 KGSDEP 1718zETA 0616zD-TO +30C FLAP 20 PACKS ONCURRENT FUEL REM 19.1 - headwinds almost all the way...I reckon this will reduce to approx 15.5 by FL 380...a nice reserve margin on arrival.CURRENT PLW 244600 KGSTry it if you get the time...I'm afraid its longhaul all the way for me these days!!