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ahaka

MD-11 manual trimming (question about real world operations)

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Hi,While learning this great airplane, particularly the hand flying part, I came to wonder if in real world the pilots use the manual trim (yoke trim switches) during normal operations when LSAS is active and operating normally?As the LSAS is limited to small inputs below 1500 AGL, it could sometimes be necessary to manually trim the airplane if I'm guessing right?What I've experienced in the simulation is that there is mainly no need of manual trimming so far, but I'm only in the beginning of my MD-11 career.I also wonder if pilots find the MD-11 easy to fly, cause so far I've found it a little trickier in some situations than the 747, or espacially the LvlD 767.

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Antti,LSAS is not limited to 1500ft AGL at all. But despite LSAS there is still a need for manual trim because pitch attitude hold is not that fast or precise. You can try this if you let go of the yoke in an out-of-trim situation. Pitch will change considerably before LSAS starts to trim and hold pitch.But yeah if the air around you is smooth and there are no large speed or thrust changes then indeed LSAS may remove the need for manual trim and you can change pitch using two fingers only.The thing is, and this can't be simulated 100% here because of unprecise yoke/joystick hardware, on the real aircraft if you move the yoke even slightly out of neutral this will deactivate LSAS pitch attitude hold until the yoke is neutral again. And as soon as this happens you need to trim manually.Generally the MD-11 is considered a bit trickier to fly compared to say a B747, mainly because of the high approach speed and a greater instability. And sometimes LSAS is more of a pain than actually helping...Markus

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You are correct that manual trimming is required. you will notice that when trimming LSAS is inactive as well until the trim input is released. the PMDG MD11 flies incredibly nice, however, the real 11 is a handful at times and flies less friendly than the PMDG. But having said that, the PMDG MD11 has captured every aspect of the handling characteristics in a fantastic way. enjoy the 11T ReynoldsMD11WOA

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Thank you for the very detailed answer Markus!I also thought LSAS can sometimes make things more difficult, but perhaps its just a matter of getting used to it. :) And there must be a reason why its fitted with the aircraft.

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Hi Mr. Reynolds,Could you elaborate a bit on the differences between the Real MD-11 handling and the handling you can see in the PMDG MD-11?I am not looking to defend the sim bird, where it has flaws (as all desktop sims with their home yoke handling obviously have), but would rather like to hear some comparison to the real deal :).I have flown a full flight MD-11 sim a few times, and remember that it wasn't hard to fly at all. Albeit a bit "quirky" but not hard. How do you find the PMDG MD-11 generally speaking, and with regard to the flight model?Thanks! :)rgds,Tero

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I've found LSAS to be magical on approach. For instance, I primarily use pitch to maintain rate a rate of descent once I've acquired GS. My method is to acquire GS, then maintain GS with rate of descent. ~ 800fpm does the trick. I find that if I use the dots, or even the command bar to adjust GS, it's just too last. The rate bar is my primary vertical cue during approach. With the 744, my primary flight control (vertical) input was the pickle switch (long trim). I would initially set ~ 800 FPM with pitch trim. Then, I was constantly tap, tap, tappin' trim as rate wandered ~ 900, ~700 FPM. (Note: if you stay on top of your rate of descent, GS will stay "on-the-dot." With the MD11, I have found that rate just locks-on. It's magic. I use control column to initially acquire GS, then trim to neutral the CC. From there, I just let go. That is the Biggest thing a new MD11 pilot needs to master. The ability to just let go. If I need to adjust rate, the input is a momentary nudge on the yoke, then an immediate release back to neutral. The 744 would have required a re-trim. The MD's LSAS "captures" this new pitch and just stays there.Try it. Get yourself set on a nice long approach. Stay in FMS Speed and let Otto handle and speed reductions. Acquire GS and settle in at ~ 800 FPM. That is a standard GS rate of descent. If you see 700, just give the CC a short, light nudge to reacquire 800FPM. Then Vica versa. It's magic I tell ya!

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Hi Sam,Totally agree.For the unversed, easy formula to calculate needed ROD on a 3-deg glide is roughly 5x your Groundspeed. So, with 150kts of Vapp in no-wind, would require 750FPM to stay on the glide. And indeed, in the bigger jets you just change your pitch to stay on the glide, not thrust.Tero

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