PPRuNe Forums - View Single Post - CNN Reports FEDEX crash in Tokyo
View Single Post
Old 23rd Mar 2009, 12:27
  #97 (permalink)  
Weapons_Hot
 
Join Date: Dec 2002
Location: Wood's Hole (N4131.0 W07041.5)
Posts: 92
Likes: 0
Received 0 Likes on 0 Posts
Absurd tail-plane incidence?

Rainboe - it depends on the CG at the time. Aft CG (circa 26.0% MAC) and trim is about 8.5 ANU. In a baulked landing with the MD11, pressing the GA switch will immediately advance the throttles to GA thrust, and command a pitch up attitude to maintain VrefGA or current IAS, which normally results (3 engines) in a pitch up attitude of about 25 deg ANU. You wouldn't want to have a hell of a lot of back-pressure on the stick when you hit the GA switch. If a GA was initiated AND the GA switch was pressed, then there would only be one flight path achieved - UP.

The wings too far back? No, that has to be a wind-up.

Now, some are talking of the #2 engine producing a downward moment when thrust is applied; that is correct. However, what is happening to the #1 and #3 engines at the same time? Remaining at idle? (a rhetorical question). These engines will negate any nose down moment caused by #2 engine, and give the airplane a nose-up moment (see above).

For those who have flown the MD11, I doubt any will opine other than when landing, it can be a handful (not impossible or unsafe) in adverse conditions, hence the correct landing technique must be used.

Someone mentioned autoland: AFM limitation - no autoland when windshear forecast/suspected (or h/wind >25kt, x/wind >15kt, or t/wind >10kt).
Weapons_Hot is offline