33
RamAir REFLEX BRIDLE ADJUSTMENT,
COMPENSATION AND FLIGHT TESTING
The
RamAir
uses three reflex support bridle lines per side (6 total) as an integral part of a
system to provide pitch stability. These lines run from an attachment to the upper compensa-
tor wire just behind the top of the kingpost to grommets on the trailing edge. Their function is
to support the trailing edge of the sail at low angles of attack, and thus provide a nose up
pitching moment.
The variable geometry system on the
RamAir
functions by moving the center hinge connec-
tion of the crossbar assembly aft along the keel, thus pushing the leading edges outward
and increasing the airframe nose angle. This results in increased spanwise sail tension and a
reduction in spanwise twist.
Two effects result from engaging the VG which both contribute to a tightening of the bridle
lines. The first - a flattening of the upward curve of the trailing edge of the sail - is relatively
minimal. The second effect - a downward folding of the wings around the axis of the keel
(because the bottom side wire length is fixed) - is much more significant.
In order to correct the bridle adjustment for the effects of tightening the VG, a bridle com-
pensation system automatically lowers the bridle attachment point at the top rear of the
kingpost as the crossbar center is pulled aft by the VG system. A lower bridle compensator
cable is attached to the crossbar center hinge, runs around a pulley in the base of the
kingpost, up inside the kingpost and around another pulley attached to the upper compensa-
tor wire, and then back down and around another pulley at the base of the kingpost and out
to a termination at the keyhole channel which secures the xbar sweep wire at the rear keel.
The upper compensator wire runs up inside the kingpost, exits the back of the kingpost over
a pulley and attaches to the bridles. As the crossbar center is pulled back, the lower com-
pensator wire is slackened, and as a result the upper compensator cable moves in such a
way as to lower the bridles. For each inch of crossbar hinge travel, the bridle attachment is
lowered one half inch.
On the upper compensator wire there is a separate fixed length pigtail which is secured
directly into the kingpost top by a ball swedge end fitting. On previous Wills Wing gliders,
and on the 146, this pigtail functions as a safety backup for the bridles to kingpost connec-
tion, and its length is such that it is always slack throughout the range of compensation
adjustment. On the
RamAir 154
, the length of this pigtail is such that as the VG is tightened,
and the bridle attachment lowered by the compensator system, the pigtail comes tight at
some point in the VG range, disabling the compensation system at that point, and holding
the bridle attachment at a fixed distance below the kingpost top. The effect of this is to
make the bridles become progressively tighter at all VG settings which are tighter than the
setting at which the pigtail first becomes tight.
