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Inverted, unloading and reducing angle of attack on Modern Jet Aircraft

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Inverted, unloading and reducing angle of attack on Modern Jet Aircraft

Old 28th May 2017, 17:18
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Originally Posted by B737C525 View Post
Stick-neutral is stick-neutral, not pitch-input-neutral.
Stab position and/or thrust may very easily overwhelm the stick input.
You may need not only to move the stick, but make aggressive changes to trim and/or thrust too.
Usually upset recovery is from a sudden event, so trim was never set to the upset condition. Main reason to train for stick-middle is to dump alpha and avoid pilot induced oscillations (PIO). Aggressive moves got the pilot in trouble more often than not. The key is knowing when to react forcefully and when to go stick-neutral (before rolling to a good attitude).
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Old 29th May 2017, 14:19
  #42 (permalink)  
 
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Hence my liberal use of 'may'...

Usually upset recovery is from a sudden event, so trim was never set to the upset condition
TK1951, AF447, N38CR, just off the top of my mind as three events in which trim played a vital (or rather, deadly) role.

Last edited by B737C525; 29th May 2017 at 14:48.
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Old 30th May 2017, 11:37
  #43 (permalink)  

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@ 111Boy,

I am sorry if my post offended you - it was a rare 'fly-off-the-handle online' moment, and abuse was not intended. However - I do believe that questioning the lack of inquisitive minds in modern airline operation does add something to the debate (even if the style of the post subtracted from this).

I think my frustration in large part stems from having taught UPRT from way before it became UPRT - and the lack of imagination encountered over the years, let alone lack of ability to consider that what was put across in the sim had any applicability in real life, has perhaps jaded my view of your average pilot group somewhat. So yes, I know what a v-n diagram is. And I know that 'imagination/creative thinking' high scores on a BMPT (ISTP, ISFP, ESTP, ESFP - you know the types) does not bode well for your airline career aspirations - but if you have examples of airlines selecting for these traits, I'd be very keen to learn.

It is encouraging that people are starting to at least ask these questions, but the lack of basic aerodynamics/flight mechanics knowledge is - with all due respect - staggering. This is why I don't frequent Prune that much - the 'professional' bit is at times lacking...
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Old 30th May 2017, 13:35
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This is why I don't frequent Prune that much - the 'professional' bit is at times lacking

Perhaps, if viewing the matter from the other side of the table, you might consider the value of education via PPRuNe .. if your background is as I suspect, your contribution could be quite useful in this regard. Maybe something to ponder ?
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Old 30th May 2017, 15:00
  #45 (permalink)  
 
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Unloading refers to removing the G-Force via application of the controls to a neutral position (either forwards or backwards depending on your start point) which is also dependant on your trim.

Power is simultaneously either increased to maximum, remains at cruise, or decreased to idle, depending on the severity of the Unusual Attitude (including factors such as IAS, Mach No and Height Available).

Aileron (up to full or limit) is usually applied to level the wings first, except for larger transport types which often increase the bank in a nose high UA before levelling it close to the horizon as the nose starts to fall through.

For a nose low UA once the wings are levelled, THEN back elevator is used to recover from the dive.

This is not a comprehensive guide, merely an outline of some of the correct actions and considerations.

Such techniques are slightly different than those learnt on dedicated aerobatic types, however exposure to such extreme aerobatic UA's makes for valuable experience and better diagnosis.
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Old 30th May 2017, 16:52
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Just read Handling The Big Jets...the section on jet upsets
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Old 30th May 2017, 17:34
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No wing will stall if the G loading is zero so pushing or pulling depends on if the Gs are positive or negative. Move the elevator to unload the G loading.

If you happen to be going straight up when you do this using rudder and making a flat yaw with the ailerons will put you in a vertical dive known as a hammerhead stall even though the wing is not stalled even when the airspeed approaches zero. I have taught hundreds of these in aerobatic planes but wouldn't suggest it in an airliner even though it might work fine if you could keep the wings flat in the rotation to vertical.
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Old 31st May 2017, 11:52
  #48 (permalink)  

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Fair point, JT - can't complain about the standards when you don't contribute much ;-) Taken on board, will try to rectify...
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