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Hi,after take off I had the situation where the climb speed was very low. Actually she was perfectly maintaining the FMS speed as per F-PLN page, but I wonder why it was at the limits...My cost index was 800 and TOGW 261000 Kg.Any idea?Thanks

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Wow, that seems to be a heavy plane. I briefly tried but was unable to reproduce your load that gave you an optimum flight level of 280. I was also unable to reproduce that speed direction on the MCDU.What loading are you using?-stefan

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Here they are. Basically full pax and around 100.000 Kg fuel. Yes it is very heavy, but still below the max. (At least according to FS loader...).

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There's your problem. Don't load the MD-11 with any of the default FSX tools. You need to use the PMDG MD-11 Load manager, which you will find in your Windows start menu. Refer to the manual for more on this, and also the tutorial flight.-stefan

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There's your problem. Don't load the MD-11 with any of the default FSX tools. You need to use the PMDG MD-11 Load manager, which you will find in your Windows start menu. Refer to the manual for more on this, and also the tutorial flight.-stefan
I know that Stefan :( The picture was taken only to show you how the weights were split.

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I know that Stefan :( The picture was taken only to show you how the weights were split.
Oh. Can you show a screenshot of the load manager?-stefan

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At that weight, 1300 fpm passing thru 20 for FL280... doesn't sound all that bad. She should maintain at least 1000 fpm to optimum. The econ climb speed of 156/0.85 looks odd, speed should be higher than max rate of climb speed. Almost looks like it forgot to accelerate above the restricted speed limitation at 10,000?

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Hi,after take off I had the situation where the climb speed was very low. Actually she was perfectly maintaining the FMS speed as per F-PLN page, but I wonder why it was at the limits...My cost index was 800 and TOGW 261000 Kg.Any idea?Thanks
Lorenzo,It's the costindex being way too high.Couple of weeks ago, some costindex numbers(680 and 685) were mentioned here.Out of curiousity I thried these:Result was a much lower than normal climb speed after passing 10000 ft in climb. In your case CI 800 will even create more drag, resulting in less climb performance.Suggest to keep CI for MD-11 below a value of 300.Regards,Harry

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Ah, that is it. Thanks Harry for bringing that up.To tell you the truth, all the real world CI's mentioned during testing were below 100. I use 100 when testing for uniformity, kinda like that must be unity. My flights are either 33 or 88, would have never seen those kind of econ numbers without your pointing it out.

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Yep definatly the CI, I was using a CI of 80 for quite a while then decided to try 150, the A/C climb above 10k was much slower.

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Thanks everybody, that's fine then. Me too have always used CI = 90 but yesterday wanted to see how higher numbers effected the trip.Best regards.

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Me too have always used CI = 90 but yesterday wanted to see how higher numbers effected the trip.
Out of curiosity: If you changed a paramenter deliberately to check for any performance changes and then indeed experience a difference in performance, why do you need to ask anymore? You yourself know the root cause well, so I'm somehow puzzled about this thread...Never mindAndreas

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Out of curiosity: If you changed a paramenter deliberately to check for any performance changes and then indeed experience a difference in performance, why do you need to ask anymore? You yourself know the root cause well, so I'm somehow puzzled about this thread...Never mindAndreas
Andreas,by increasing the CI is the airplane supposed to accelerate or to slow down the climb and cruise speeds?

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Out of curiosity: If you changed a paramenter deliberately to check for any performance changes and then indeed experience a difference in performance, why do you need to ask anymore? You yourself know the root cause well, so I'm somehow puzzled about this thread...
Hehehe, I thought the same. :( Imagine I'd think 'Okay, lets see what happens if I land without flaps'... after which I bump HARD on the runway during landing. And then I would come over here to post a topic called 'Bumpy landing... why?!?' :(

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I use a CI of 80 it will give you higher altitudes than 90 . 0ver 100 is just ridiculous . Also set to 80 you can set it to max weight and you wont even notice , the MD-11 packs some serious power just watch one take off its a great site to see . Its not nicknamed the rocket for nothing . Boeing made a mistake stopping production .Lee Marrow

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anyway nobody replied to my question. The fact is that the higher the CI the faster should be climb and cruise speed. If that is untrue, then apologies to all I am not a real pilot and I need to learn; if that is true, then we have a problem to report (and that's why I open the thread).It wasn't my intention to create false alarms here.

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anyway nobody replied to my question. The fact is that the higher the CI the faster should be climb and cruise speed. If that is untrue, then apologies to all I am not a real pilot and I need to learn; if that is true, then we have a problem to report (and that's why I open the thread).It wasn't my intention to create false alarms here.
Let me link to an article on the Boeing site that explains the use of CI... to try and explain it here would take too long :Dhttp://www.boeing.com/commercial/aeromagaz...07_article5.pdfI think the issue you have is the high CI: look at the last page of the article, a high CI leads to a flat climb, as low CI minimizes fuel to climb...That certainly looks like the behaviour you experienced... though I do not understand the speed being so low... it should be a lot nearer Vmo/Mmo with a flatter climb... perhaps a combination of the enormous TOGW and CI?Andrew

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Thanks Andrew, that it what I was looking for...then I must admit the MD11 is perfectly simulated.Cheers

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Let me link to an article on the Boeing site that explains the use of CI... to try and explain it here would take too long :Dhttp://www.boeing.com/commercial/aeromagaz...07_article5.pdfI think the issue you have is the high CI: look at the last page of the article, a high CI leads to a flat climb, as low CI minimizes fuel to climb...That certainly looks like the behaviour you experienced... though I do not understand the speed being so low... it should be a lot nearer Vmo/Mmo with a flatter climb... perhaps a combination of the enormous TOGW and CI?
hi, thanks for the link that is very interesting. i found this thread by searching because i was having a similar issue. i have been working on a fuel profile for the md-11 for fsbuild and have everything accurate including step climbs and stuff matching now, but the default cruise burn data i was working with (just what came with fsbuild, i think it's from an md-11 manual somewhere) seemed to be designed around a CI of 675. everything matches perfectly except while climbing the desired econ speed was ridiculously low.after reading the link, i'm still puzzled, however, as to why the high CI values should result in very low econ climb airspeeds. it would seem to me that a flatter climb would go hand-in-hand with higher desired airspeed. i can't really figure out why the econ climb dramatically drops off after CI values over 500+ almost to lew speeds that are barely above stall speed. all i can guess is that it is trying to maximize vertical speed and not airspeed during the climb phase? if so, why would that operate differently than at cruise where high CI maximizes airspeed? if values higher than 100 are not realistic for real world, is it just that the behavior is undefined past that point? i just don't really get why the curve drops off rather than just approaching vmax.cheers-andy crosby

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