Wills Wing Fusion 141, Owner'S Service Manual

Page: 39 / 68

— 31 —
Fusion Sprog Adjustment and Flight Testing
The Fusion uses one internal sprog per side in combination with one transverse batten spanning three
chordwise battens as an integral part of a system to provide pitch stability. Their function is to support
the trailing edge of the sail at low angles of attack, and thus provide a nose up pitching moment.
Sprog measurement
The sprogs are adjusted at the factory to their proper settings. You can check this adjustment as
follows:
1. Fully assemble the glider and then lay it flat on a level floor. Place enough weight on the nose and
the rear end of the keel so as to press them against the floor (the rear keel will have the basetube
between it and the floor).
2. Measure the height of the trailing edge at the number four battens above the floor. This should be
at least 11.5".
Alternate sprog measurement
1. Fully set up glider, VG Loose on a reasonably level surface.
2. Place two equal supports, about 30" tall, under the rear end of each leading edge, so as to lift the
keel off the ground and take up any slack in the bottom side wires.
3. Tie a lightweight thread tightly across wing from one # 4 batten end to the other. (The number four
is the middle batten supported by the transverse batten, and the one immediately adjacent to the
sprog.)
4. Press firmly on end of #4 batten, release, then measure the height of the thread above the keel. This
should be 5.5"
5. Note that this method will not disclose sprogs that are assymetric. If, after achieving the 5.5"
measurement, you have a turn in the glider which is only present at tighter VG settings, lower the
sprog on the side the glider is turning towards, and raise the other sprog by the same amount.
Method of adjustment
1. To adjust the sprog height, fully unzip the access zipper to gain access to the sprog center junction.
2. Unbolt the sprog cable from the center junction, taking care to maintain the rotational alignment of
the sprog at its original setting.
3. At the front of the sprog is a threaded adjuster. To raise the sprog, turn the entire sprog counter
clockwise. To lower the sprog, turn it clockwise. One full turn raises or lowers the sprog about one
half inch.
4. Re-attach the sprog cable and press down firmly on the rear end of the sprog to seat the cable
before checking the measurement again.