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JHepburn

LSAS Help

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So, I've read through the manual a few times and done some test flights, but I still don't fully understand LSAS.I feel like I'm most likely fighting it when hand flying, but the problem is I'm not sure what to expect. Can someone outline what LSAS provides? 1. Should I expect to roll to any bank angle up to 30 and neutralize the yoke to hold the angle?2. What should I expect in terms of auto trim? i.e. only in level flight? throughout all bank angles?3. Should changes in trim due to autotrim display on the SD?4. Is autotrim slow to react? i.e. should I expect to be manually trimming?5. When rolling (at any rate), should I expect to have to stop the roll input with by deflecting the ailerons in the opposite direction? Feels like a lot of inertia, but other quality addons don't do this...I just don't have a real-world frame of reference to compare to.Any tips for hand-flying and how best to handle this beast would be helpful. I've been practicing which has definitely helped but still feel I'm missing something. Thanks!

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LSAS has nothing to do with bank angle or roll. It's purely related to pitch attitude. This is NOT Airbus style FBW.

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Adding to Ryan's response, you have to adjust pitch in bank just like most aircraft (this is not "automatic"). The LSAS stabilizes the pitch attitude but you are still flying the airplane. Most importantly, don't overcontrol and fly smoothly as if you have paying passengers.

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LSAS has nothing to do with bank angle or roll. It's purely related to pitch attitude. This is NOT Airbus style FBW.
Thanks Ryan/Dan,Sorry, I was thinking about Roll CWS which is mentioned in the manual as well. Is this modelled on the PMDG bird (the manual says "if installed").With regards to LSAS, lets talk technique. --Should I expect to trim once to neutral and then LSAS will maintain attitude?--Should I expect to re-trim with a power setting change if I want to keep the same attitude?--Is neutral force (i..e zero force) what the FCC looks for to autotrim, or does it look for the yoke being held steady (i.e constant force) and then autotrim does its thing to neutralize the yoke.I realize its not an airbus, but my problem is that I don't understand the operational capabilities.Thanks!

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I think you're over-thinking the LSAS a bit. Just fly it like it's another plane. Douglas only introduced LSAS to help with the decreased stability caused by the much smaller horizontal stabilizer on the MD11. From what I recall, if the control column force is under 2lb, LSAS will move the stab to trim off the force. Now I've read where many European pilots talk about applying so many pounds of force to the control column, and for the life of me I can't figure out how they estimate those numbers.The RCWS will maintain the bank angle selected up to 30 degrees. In the pitch axis, you still need the trim, but during approach, the LSAS will trim out small pitch changes (~1 degree), but you must be in trim to begin with. Thus, the MD is fairly stable in smooth air.I've never really tested the trim changes during flap and thrust changes, but I suspect it'll be conventional. I think of the MD11 flight controls as the half way point between the Airbus logic (g-load and roll rate) and Boeing logic (conventional control).

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I think you're over-thinking the LSAS a bit. Just fly it like it's another plane. Douglas only introduced LSAS to help with the decreased stability caused by the much smaller horizontal stabilizer on the MD11. From what I recall, if the control column force is under 2lb, LSAS will move the stab to trim off the force. Now I've read where many European pilots talk about applying so many pounds of force to the control column, and for the life of me I can't figure out how they estimate those numbers.The RCWS will maintain the bank angle selected up to 30 degrees. In the pitch axis, you still need the trim, but during approach, the LSAS will trim out small pitch changes (~1 degree), but you must be in trim to begin with. Thus, the MD is fairly stable in smooth air.I've never really tested the trim changes during flap and thrust changes, but I suspect it'll be conventional. I think of the MD11 flight controls as the half way point between the Airbus logic (g-load and roll rate) and Boeing logic (conventional control).
Thanks Check,I'm glad you're around these parts (and the Level-D forums). As always, a great help.

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Any tips for hand-flying and how best to handle this beast would be helpful. I've been practicing which has definitely helped but still feel I'm missing something. Thanks!
Some of the beta team were discussing this recently. For the approach, a good piece of advice that came out of the discussion was to make small, individual adjustments, and wait to see how it affects the aircraft before making another. The term "bump 'n' nudge" was used to describe it.You can switch on the flightpath vector to get an indication on the PFD of your trajectory, from there it's just a case of making small adjustments to match your flight path angle to that of an optimal approach (normally -3 degrees)Lately I've found myself handflying most of the STAR just because it's so darn easy and fun!

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Some of the beta team were discussing this recently. For the approach, a good piece of advice that came out of the discussion was to make small, individual adjustments, and wait to see how it affects the aircraft before making another. The term "bump 'n' nudge" was used to describe it.You can switch on the flightpath vector to get an indication on the PFD of your trajectory, from there it's just a case of making small adjustments to match your flight path angle to that of an optimal approach (normally -3 degrees)Lately I've found myself handflying most of the STAR just because it's so darn easy and fun!
What is the flightpath vector and how do you turn it on?

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What is the flightpath vector and how do you turn it on?
It's in the docs but push the button above the V/S indicator on the glareshield.Rob

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It's in the docs but push the button above the V/S indicator on the glareshield.Rob
FPA?

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FPA = Flight Path Angle, so yes, that's what you're looking for.
Thanks mate

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Thanks mate
Sorry Andrew, I wasn't very clear in my explanation: Pressing the FPA button allows you to select a Flight Path Angle instead of a Vertical Speed, it also causes the Flight Path Vector to display on the Primary Flight Display, this is the little airplane symbol that shows the direction of the airplane's flight.Apologies for the lack of clarity!

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Sorry Andrew, I wasn't very clear in my explanation: Pressing the FPA button allows you to select a Flight Path Angle instead of a Vertical Speed, it also causes the Flight Path Vector to display on the Primary Flight Display, this is the little airplane symbol that shows the direction of the airplane's flight.Apologies for the lack of clarity!
No worries!

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LSAS has nothing to do with bank angle or roll. It's purely related to pitch attitude. This is NOT Airbus style FBW.
Ryan/Dan,Sorry to dredge this old thread up, but I think I've solved my issue with LSAS not working. Does LSAS work if controllers are piped through FSUIPC?I setup my yoke directly through FS9 interface (rather than FSUIPC configuration/calibration) and all works perfectly. Autotrim maintains pitch with configuration and power changes where it didn't before!!If this only works through FS9 interface, then you guys should consider a wiki or readme entry. Thanks again for the help!!

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That I do not know... I will ask Vangelis about it.

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That I do not know... I will ask Vangelis about it.
I am also a little bit confused about LSAS, particularly the option in the PMDG menu that relates to sensitivity? Can you explain what this is for. I have read the manual regarding it but I'm not 100% sure. Does for example setting the sensitivity to Light make the LSAS function less aggressively or does light reffer to joystick pressure etc. Will setting the sensitivity to light make the LSAS react with less input from the controlsAny help would to understand this would be appreciated.Thank YouBarrie Davies

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Hi,LSAS sensitivity:SOFT - seems to slow down the LSAS, so it takes longer for it to trim out.HARD - seems to make the LSAS function quicker and makes the pitch more sensitive (I found anyway).LSAS is functioning as long as you are within the LSAS roll limit (denoted by a white arc on the roll angle indicator of the PFD).I find m anual trim is required when she's light particularly. Once you're close to trimmed flight with neautral controls, LSAS will take up the last bit and she'll maintain a constant attitude.If you are light and make rapid speed changes, LSAS can't keep up, but when she's heavy, LSAS makes flying easy.If you pull up the 4th display in the pop-up, and watch the trim, even when she's a long way out of trim, LSAS will eventually wind the trim to where it needs to be.It's not as fast as manually trimming though, should you require it. Once it's trimmed, and as long as you're smooth, LSAS does a great job.Best regards,Robin.

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Would you say that manual trimming should be used as the main means to trim the md11? Since using the md11 I have always assumed that LSAS was the primary source of trim on the aircraft and that you had to rely on it to take care of the trim for you, kind of like the fly by wire of the Airbuses. Can you suggest any flying tips with regards to trim. I guess all I have been doing is pitching to the amount I want and letting the stick go, relying on LSAS to trim for me. Perhaps this is not the best technique?ThanksBarrie Davies

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longitudinal stability AUGMENTATION system. The MD11 does not have autotrim. Fly it like a conventional plane (because it is), and the LSAS will trim away very small control column forces (~2lb i think).Paul

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longitudinal stability AUGMENTATION system. The MD11 does not have autotrim. Fly it like a conventional plane (because it is), and the LSAS will trim away very small control column forces (~2lb i think).Paul
Paul,With all respect, please update yourself.The MD11, also in this respect, is not conventional.Refer to Systems, Flight controls, FLT.10.11.You can fly it in the conventional way if you like, but as Barrie suggests, it's more comfortable to use the LSAS features.Regards,Harry

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Apologies Harry, I was posting in a haste. I was trying to get across the point that Barrie was overthinking it a bit. What he described seems more akin to Airbus Normal Law. You fly the plane so correct me if I'm wrong here, but my understanding is that LSAS only makes small corrections, and doesn't correct a for grossly out of trim situation like the Airbus would. You still have to put in some work to get it where you want it, but the LSAS jsut helps you fine tune the pitch. Am I wrong?Paul

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Is there a technique to trimming the aircraft after takeoff rotation? I gently rotate the aircraft and try to follow the FD bars in order to maintain pitch at V2+10. What I find is that the aircraft's LSAS has to adjust the trim quite alot once I have released the pressure on the yoke. For example take off pitch maybe 6.0 but after rotating and adjusting pitch to maintain V2+10 then elevator pitch alters quite alot down to around 3-3.5 in some cases even less.Should I be manually trimming the aircraft after rotation or allow LSAS to do it all? I was under the impression that LSAS should be relied upon for small pitch changes.Barrie Davies

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You shouldn't need to be re trimming, LSAS isn't there to make pitch changes as far as I know thats your job it just trims out to take the load off the yoke. Having a trim like 6 on take off doesn't mean 6 is needed on initial climb as the extra pitch is there to help to rotate the aircraft off the ground with relative ease, you probably don't need that much pitch at V2+10. LSAS should slowly adjust whatever pitch it needs to reduce pressure on the yoke.In the end it is up to the pilot, if you feel like trimming then go ahead but I wouldn't worry about the exact degree of trim LSAS is tweaking as you accend, as long as it feels comfortable.

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Is there a technique to trimming the aircraft after takeoff rotation? I gently rotate the aircraft and try to follow the FD bars in order to maintain pitch at V2+10. What I find is that the aircraft's LSAS has to adjust the trim quite alot once I have released the pressure on the yoke. For example take off pitch maybe 6.0 but after rotating and adjusting pitch to maintain V2+10 then elevator pitch alters quite alot down to around 3-3.5 in some cases even less.Should I be manually trimming the aircraft after rotation or allow LSAS to do it all? I was under the impression that LSAS should be relied upon for small pitch changes.Barrie Davies
Barrie,Do you calibrate and assign your pitch axis via FSUIPC?

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