Then grip the keel at its centre between
finger and thumb and launch gently. Mark how your glider behaves. If it
plunges persistently, trim off a very little of the head. If, on the
contrary, it settles almost vertically, weight must be added in front. The
position of the weight is soon found by sliding a metal clip along the keel
until a good result is obtained.
Note that if the leading edges of the front wings are bent slightly
downwards the glider may fly much better than before.
A good specimen of this type is so stable that if launched upside down it
will right itself immediately and make a normal flight.
Model "C."--This is cut out of doubled paper according to the solid lines
of Fig. 128. The three sets of planes are bent back in the manner already
described, but the front planes are given a somewhat steeper angle than the
others. This type is very stable and very fairly efficient.
General Remarks.--Always pick up a glider by the keel or middle, not by
one of the wings, as a very little distortion will give trouble.
The merits of a glider depend on length, and on straightness of flight; so
in competition the launching height should be limited by a string stretched
across the room, say 6 feet above the floor.
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