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Guest martinfoss

747 flap question..

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Guest martinfoss

Hi. Bought the 747 last week, and have been spending some time with it this weekend, with the lessons posted on the PMDG-site. I must say, thank you for a great product. I'm really impressed.Anyway: I take-off, and do it "after the book". Keep the purple cross centered, and retract the flaps when I'm supposed to. From 10 to 5, everything seems normal, but from 5 to 1, and 1 to fully retracted, they don't seem to move. Speed never exceeds 250, so I don't think they're broken or something. And again, thanks for a great plane. turned out to be ny first payware plane, and I don't regret spendiing those money

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The flap retract speed from 5 to up is very slow. I believe this was done to represent the way the real aircraft does it. Of course having never been in a 747 I dont know if it's the real speed of retraction but knowing PMDG's attention to detail I bet it's exactly right.


Andrew

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Guest martinfoss

I haven't been in a 747 either, so I wouldn't know. But if your 747 behaves the same way, I suppose it's supposed to be like that..Thanks :-)

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Martin the simulator reproduces the normal flap speeds very well. In the secondary mode they move a little bit too fast but close enough to get the point across that they are alot slower due to being driven by electric motors rather than hydraulics. In the normal mode flap 5 to 1 is quite slow as the trailing edge flaps move a long way horizontally as well as thru the 5 degrees. At the flap 1 position the trailing edge flaps are all fully retracted. From 1 to up it is just the inboard and mid leading edge flap group retracting. They are pnuematically driven and take a little time to operate. The whole flap system on this aircraft is a real wonder.CheersSteve


Cheers

Steve Hall

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Gidday Michael....so I was......my apologies.I tried it the other day in the a/c and cost index 9999 is the maximum entry (at least for a GE powered 747. I haven't tried it on the RR powered models yet). 9999 is academic as no one would ever use it and in fact in the real world I would be surprised if any operator were to use higher than 300.Cost index 0 is an ECON speed and equates to maximum range speed in still air. In theory it will give you the maximum Ground nautical mile per KG of fuel. I say in theory because there are speed stability issues with it and therefore more fuel could be used to try to maintain that speed (A/T's constantly moving to control speed)than actually flying a little faster and being more speed stable The cruise speed produced will be dependent on the wind. Faster into a headwind and slower with a tailwind. Also as fuel is burnt off and weight decreases, the speed will be slower. It is also dependent on the altitude flown in relation to optimum.LRC is approx 1% faster. LRC is not an ECON speed as such and is constant for a given weight and altitude regardless of wind component. This speed would need to be entered manually or a cost index entered that would equate to LRC at that time. A cost index of 50 to 100 would equate to LRC for most circumstances. Remember that cost index is looking at the cost of fuel V's other costs (maint, crew etc). A cost index of zero means that fuel is the only consideration and a CI of 9999 means time is the only consideration and to #### with fuel costs. You might like to have a look at this site.http://www.pprune.org/forums/showthread.ph...ight=cost+indexCheersSteve


Cheers

Steve Hall

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>>LRC is approx 1% faster.Based on the link you provided it looks like LRC results in about 3-4% increase in speed at the expense of additional 1% of fuel cost - that would agree with the definition that I knew. I go by what Clipper811 says since he sounds like he knows it best. He claims that ECON = MRC **only** for CI = 0. He also points out that LRC is a fixed number - it won't change if cost index changes (makes sense). He implies (though never clarifies) that ECON speed will change if CI changes. Still not sure though what ECON is. It sounds it is simply the least-cost speed based on the current cost index - in other words if you selected your CI you automatically get ECON. LRC seems to be directly accessible through the FMC so perhaps it is very easy to set it up.Thanks.Michael J.http://www.precisionmanuals.com/images/for...argo_hauler.gifhttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg


Michael J.

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Sorry Michael I meant that it uses 1% more fuel (in theory) not 1% faster.Long range cruise is not a fixed number as the value varies with weight and altitude. ECON is just the speed the FMC computes dependent on the entered CI. It calculates Climb, cruise and descent speeds based on weight, altitude and wind. LRC is accessible on the cruise page. The speed will only vary with weight and altitude and not wind.CheersSteve


Cheers

Steve Hall

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Guest capntom

Flaps are only electric in the alternate mode. Trailing edge flaps are normally drive by Hyd systems 1 & 4 and the leading edge devices are Pneumatic, in normal operation. If in electric backup both are much slower.At a heavy weight, ya need about 280 knots for full manuver capability at flaps up!Tom

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