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-   -   330/340 T/O Pitch Response (https://www.pprune.org/tech-log/9413-330-340-t-o-pitch-response.html)

jtr 24th Sep 2000 21:20

330/340 T/O Pitch Response
 
Was wondering if anyone has any ideas why the 340/330 nose leaps skyward at higher (i.e. 6 or 7 units) pitch settings, and not so at the other end of the band?
When you think about it in relation to GWCG position, and rudder/wheel arms, it doesn`t make sense... or does it?

Checkboard 25th Sep 2000 07:25

As the angle of attack increases on a wing, the centre of pressure moves forward. On wide chord wings this results in a pitch up.

On fighter aircraft with very wide wings in relation to the body this pitch up tendency can exceed the elevator authority.

I have seen video of fighter takeoffs where this has happened, and the only option was to eject.

jtr 25th Sep 2000 08:36

Thanks for the answer. I was thinking more in terms of the initial rate of rotation (pitch change) as opposed to any wing reaction.
Whilst I appreciate that the horiz. stab. is ititially set at a higher AoA (albiet -ive), and therefore will give a greater response at the initial application or rotation force, I thought this would have been more than offset by the CG position.
Also wonder if the new buses 340-500, A3xx etc, will take of in ground mode (direct law), or will have some pitch damping. It is scarey enough doing three weeks long haul on the 340, then a 330 jolly to realise the variences. Surely they wouldn`t be able to MFF the new derivatives when they really don`t fly similarly at the most critical phase of flight.


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