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JSACKS

De-rated N1 to initial cruise in the 744?

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If you take off with FMC de-rated thrust in the Queen, you automatically revert to full CLB power by FL150. From then on, you can find your rate of climb in VNAV is very high, especially if not heavy. Do operators of the 744 ever keep de-rated N1 on up to initial cruise or up to say FL300 to avoid climbing too fast? For example, I go into the THR LIM page and click on CLB 1 at FL150 or slightly below in order to keep N1 at a lower level for the VNAV climb to initial cruise. Is that realistic (or practical) in the real machine?Jonathan


Jonathan Sacks

Dell XPS Gen 4, Pentium IV Northwood extreme 3.8Ghz, 3Ghz RAM, eVGA 7900 GTO,

12 GoFlight modules plus MCP-PRO AP and EFIS, GF pedestal, CH rudder pedals,

CH throttle quadrant, 42" LG LED, 24" DELL LCD, Windows XP, FS2004, FSUIPC 3.96

FS Autostart 1.1 (Build 11), FS Navigator 4.6, UT, FE, GE, REX, PMDG, Level-D, PSS, etc.

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Jonathan,As you climb higher you will use higher thrust on the engines with lower fuel flow and you need that thrust to compensate for the thinner air and the decreasing lift. What you are experiencing is quite normal, I would say. For real world ops I would guess you keep the CLB setting.Hope it helps,


Mats Johansson
PMDG Flight Test Dept
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Guest capntom

No matter what derate you use for takeoff and initial climb, you will get rated climb thrust above about 15,000', at least with the GE setup. Surprisingly better power and a better climb rate gets you to altitude faster and makes higher altitudes possible at an equivelent weight, making more efficency possible.Tom.

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Thanks for these replies. I also asked because I think I observed in the Virgin 744 video to SFO that N1 was often at around 98-99% during the higher part of the climb as compared with a somewhat higher N1 in the PMDG Queen. Still I take your points and now I think I shall stick to regular CLB power above FL150 to get to initial cruise a.s.a.p.Jonathan


Jonathan Sacks

Dell XPS Gen 4, Pentium IV Northwood extreme 3.8Ghz, 3Ghz RAM, eVGA 7900 GTO,

12 GoFlight modules plus MCP-PRO AP and EFIS, GF pedestal, CH rudder pedals,

CH throttle quadrant, 42" LG LED, 24" DELL LCD, Windows XP, FS2004, FSUIPC 3.96

FS Autostart 1.1 (Build 11), FS Navigator 4.6, UT, FE, GE, REX, PMDG, Level-D, PSS, etc.

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