ane, it has much larger weight-carrying capacity.

Proper Sizes For Frame.

Allowing that the biplane form is selected the construction may be
practically identical with that of the 20-foot glider described in
Chapter V., except as to size and elimination of the armpieces. In
size the surface planes should be about twice as large as those of
the 20-foot glider, viz: 40 feet spread instead of 20, and 6 feet deep
instead of 3. The horizontal beams, struts, stanchions, ribs, etc.,
should also be increased in size proportionately.

While care in the selection of clear, straight-grained timber is
important in the glider, it is still more important in the construction
of a motor-equipped flying machine as the strain on the various parts
will be much greater.

How to Splice Timbers.

It is practically certain that you will have to resort to splicing the
horizontal beams as it will be difficult, if not impossible, to find
40-foot pieces of timber totally free from knots and worm holes, and of
straight grain.

If splicing is necessary select two good 20-foot pieces, 3 inches wide
and 1 1/2 inches thick, and one 10-foot long, of the same thickness and
width. Plane off the bottom sides of the 10-foot strip, beginning about
two feet back from each end, and taper them so the strip will be about
3/4 inch thick at the extreme ends. Lay the two 20-foot beams end to
end, and under the joint thus made place the 10-foot strip, with the
planed-off ends downward. The joint of the 20-foot pieces should be
directly in the center of the 10-foot piece. Bore ten holes (with a
1/4-inch augur) equi-distant apart through the 20-foot strips and the
10-foot strip under them. Through these holes run 1/4-inch stove bolts
with round, beveled heads. In placing these bolts use washers top and
bottom, one between the head and the top beam, and the other between the
bottom beam and the screw nut which holds the bolt. Screw the nuts down
hard so as to bring the two beams tightly together, and you will have a
rigid 40-foot beam.

Splicing with Metal Sleeves.

An even better way of making a splice is by tonguing and grooving the
ends of the frame pieces and enclosing them in a metal sleeve, but
it requires more mechanical skill than the method first named. The
operation of tonguing and grooving is especially delicate and calls for
extreme nicety of touch in the handling of tools, but if this dexterity
is possessed the job will be much more satisfacto