Advance Bibeta Manuel D'utilisation page 44

The trimmers don't need setting up before use - just make sure that
they are closed before takeoff (in the normal position i.e. unaccele-
rated). To open them in the air press the spring-loaded catches si-
multaneously (See point Riser Illustration). To close the trims, pull
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the blue loops on the ends of the straps down as far as possible. The
spring-loaded trimmers allow the setting to be adjusted as and when
the pilot wishes, and the setting remains locked even under high loa-
ding.
In accelerated flight the rear risers are lengthened and this reduces
the angle of attack of the wing. The accelerate system on the
BIBETA 4 is so designed that the wing profile remains the same in
accelerated flight (reduced angle of attack). This keeps the best wing
shape at higher speeds.
Caution: Keep the trimmer settings symmetrical.
Caution: When the trimmers are open the brake handles will
be in a noticeably higher position than in unaccelerated
(normal) flight.
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