MD11 Leading Edge Slats

[brucek 38]

I did a quick search but didn't find this answer.In the PMDG MD11 version, there appears to be only one stage of slat movement. Some aircraft, including the DC-10 (MD11 predecessor) as far as I know, have a second stage of slat extension that is deployed on approach only and adds significant drag, and often is deployed only on the outer bank of slats (as is the DC-10). Was there ever another MD11 version that had the second stage of slat deployment, or are all MD11's like the one that PMDG created and have only one stage of slats, and if so, is there a reason for this? Thanks, Bruce.

[mburkhard 23]

Bruce,there's no other version regarding slats than the one you see in the PMDG MD-11. Of course I have no idea why Douglas thought this was the perfect solution and not another one. Are you sure about the double slat detent on the DC-10? My knowledge about this aircraft is limited indeed but maybe you are confusing this with the auto slat extension for a low speed protection, which is on the outer slats only?Markus

[brucek 38]

DC-10 has 2 slat settings, 15 and 25 degrees if my memory serves correctly.The first is used for t/o and the second position is set on appr at flaps>22deg (maybe confusing this value for gear warning). In any case slats are deployed at full extent for flaps landing setting of 35/50deg.Full slat deployment from ret position takes approx 14 seconds

Thanks guys for the replies.I got to think about this question on a flight this past week on SWA (B73-7), and noted the second stage of slats on the approach to landing. It got me thinking- other than the B74 (obviously with the different LE system), I think that almost every other jet aircraft I have flown on has some form of second slat stage for approach only, so I wondered why the MD-11 did not. BTW, the B75 has a very significant increase in drag caused by the second stage slat deployment, much more so than what I saw on the B73 this week, but I recall that the entire leading edge is deployed into the second stage, rather than just the outboard on the B73, and the DC-10, as I recall.Thanks, Bruce.