LSAS Help

[Tabs 2,790]

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

[brdavies 0]

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

[3-2-1-Now 126]

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.

[brdavies 0]

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

[Check_Airman 3]

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

[KCA9304 0]

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

[Check_Airman 3]

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

[brdavies 0]

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

[VIPERGTSR01 22]

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.

[JHepburn 0]

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?

[brdavies 0]

Yes I have calibrated and assigned my pitch axis to work through fsuipc (v4.60 registered).Barrie Davies

[JHepburn 0]

Yes I have calibrated and assigned my pitch axis to work through fsuipc (v4.60 registered).Barrie Davies

Ok, I think that is the issue (although undocumented). Try 1 of the 2 options below using aircraft or profile specific settings in FSUIPC:1. On the axis assignment tab, for your elevator axis, select "Send to FS as normal Axis" and then select elevator from the drop down list. You should still be able to calibrate via FSUIPC. I believe this works and will be your best option.2. On the axis assignment tab, for your elevator axis, click "Ignore Axis" and then setup that axis in your FS Axis assignment menu. Note: You will have to remove that assigment when using other aircraft. I'm absolutely sure this works but is much more inconvenient.Let me know if this works for you.

[brdavies 0]

I still find that the trim correction is a quite excessive. Maybe I should try using derated thrust? This way maybe the fd will not require such a high angle to maintain V2+10 and I will not have to trim so much off the intial TO trim setting.Barrie Davies

[JHepburn 0]

I still find that the trim correction is a quite excessive. Maybe I should try using derated thrust? This way maybe the fd will not require such a high angle to maintain V2+10 and I will not have to trim so much off the intial TO trim setting.Barrie Davies

Shoot me your weights, runway, and metar, and I will run the derates through topcat.A good way to see if you're LSAS is working as expected is to, while trimmed for level flight, add or remove power and see if the pitch is held (not the vertical speed).

[brdavies 0]

Will try level flight and see how the LSAS reacts.My TOGW 231.684KG Runway 30 (EGFF) 2392meters Winds are 280@15knts Temp 18C Q1021ThanksBarrie