Re: spoilers used during take-off???

Date:         25 Aug 98 00:53:39 
From:         "S.L." <look@the.sig>
Organization: Applied Research Laboratories - The University of Texas at Austin
References:   1
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Maria & Thomas Eidrup wrote:
> I flew with a modern verion of Boeing 737, Falcon Aviation, from Malmoe in
> Sweden to Athens the 29 of May. To my surprise I saw the spoilers go up
> during acceleration for take-off. As far as I know they should only be used
> during landing to destroy the lifting force. Therefore I was more than
> puzzled. The spoilers went in again some seconds before rotate. Is there
> anyone who can give me an eplanation to this. Was everything the way it
> should have been?

I've noticed that on many passenger aircraft, the spoilers are deployed
asymetrically at low speeds whenever the pilot needs more roll authority
than the ailerons alone can provide. For example, if the pilot (or
autopilot) calls for a *lot* of roll to the right and the ailerons can't
do it all because of low airspeed, the spoilers on the right wing *only*
will deploy to provide a greater rolling moment to the right. The
spoilers on the left wing won't deploy in such a case. I've seen this a
few times during approaches with a lot of turbulence, and once or twice
on takeoffs with a lot of crosswind.

I understand that there are a few aircraft out there that *solely* use
spoilers for roll control and don't even have ailerons. A friend was a
B-52 and  has told me that the B-52 is such an airplane and handles a
bit differently than other large planes as a result (although the B-52
has enough oddities that I'm sure there are *many* reasons for it to
handle differently!)

--
Stephen Lacker
Applied Research Laboratories, The University of Texas at Austin
slacker@arlut.utexxas.edu (Remove the extra 'x' to mail me)