Hi,I would like to ask if there are any differences in fuel consumption for the 3 different engine variations available for the 747-400 in reality.And, if so, are these differences modelled in the PMDG 744?I have a self-developed flight planning tool and so far I reach my destinations within 1000kgs/2000lbs of calculated burn. All calculation figures are based on hundreds of flights - all with GE engines - and just by incident I used for one of my last flights the PW version - and my calculated fuel figures where way off - on a 6000nm flight I used roughly 6800 kgs MORE fuel.... that is, the FF by min or hr was about 3,5% higher than with the GE version.Karl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman Fosterhttp://www.precisionmanuals.com/images/forum/747400.jpg

Yes, there are real world variations in performance and fuel burn. No, the differences are not modeled in the PMDG- only the instrumentation. There is only one thrust model.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |

I have read around the place numerous times now that the RRs tend to use a little bit more fuel than their PW and GE counterparts, but I couldn't point you anywhere I'm afraid to back it up right now. I do remember reading a few times that there was also some little benefit of the RRs over the other two that sort of offset that, but have no idea what it was now.CheersRudy

Umm you sure about that Carl? I'll have to verify with EV but I'm almost positive he did actually construct separate performance libraries for each engine type when we did the 400F addon.

Well, I wasn't expecting this result. I just plugged identical flight plans into the GE'd and then the RR'd default 744 in FSX. It was the canned KSFOEGLL001.rte and a nice long run. Burn was identical. - Identical - . Hummm? I don't know the comparative/individual burn characteristics of these engines, only to recognize they exist. There should have been a difference if the engines were individually modeled. Remember a while back, we looked at a comparison burn between a real world 744 EGLL/KLAX flight and the PMDG airplane. Burn was remarkably close . . . amazingly close, actually. The comparison was with the GEs. If the engines have a single model, it has gotta be GE.Someone else try it too.

Ryan:That is my observation/opinion from several hundred hours of operation- but Dr. V would be the final authority. Everything seems to mirror the GE thrust and performance model despite the variant based instrumentation. Let us know.........Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |