737 tailplane adjustment?

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The Ryanair 737-800 I flew on the other day seemed to have some sort of adjustment available for the tailplane; the forward part of the horizontal section had a curved slot about two feet long; so I presume there is some sort of pivot at the rear of the tailplane by the elevator itself. Is this to compensate for loading or something else? Thanks.

[FlyingForFun]

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I suspect that what you're looking at is the trim.

Not sure if you've ever flown a light aircraft or not - your profile doesn't give too much away. If you have, you've probably seen a trim tab on the back of the elevator of Cessnas and the like. The problem with the trim tab is that it sticks out into the airflow, and creates drag. Moving the whole of the tailplane achieves the same result, and is much more efficient aerodynically. The same thing is used in a small number of light aircraft, too - head down to your local airfield and have a look at a Piper Cub if there's one around.

I'm sure that 737 pilots would have a lot more to add. I could probably add more myself, from a light aircraft point of view at least, but without knowing how much you know about what the trim system does I don't really know where to start.... Hope that helps, though.

FFF
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[FlightDetent]

http://www.houseman.cz/foto/stab_trim.jpg

Supposing this is what you are referring to ... FFF is indeed correct.

On larger planes, the whole stabiliser may be positioned to various angles of incidence, thus relieving the pressure within the elevator control system. This is also done by other means on smaller airplanes (forementioned trim tabs).

The sweet spot of this solution is that you also decrease the shape drag of the horizontal tail surfaces (unlike with the trim tabs). You will find slots like that on all transport aeroplanes, though they may be sometimes shielded with a cover.

http://www.houseman.cz/foto/stab_trim310.jpg

The slot itself is there for the forward hinge mechanism that moves up and down. Seek more info from an engineer, which I am not.

Cheers,
FD.

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Thanks for the answers; I thought the slot might be something to do with trim. I do, or have flown light aircraft and this is, as you say, just a more sophisticated trim tab.