The Washington times., 1918-12-29

PHILADELPHIA, Dec. 29.-There
are more than 100000 parts in one
large seapIane, built at the Naval
Aircraft factory. The absence of any
one OF these parts may hold up the
assembly of an, entire boat. Every
part must be perfect. 1t must be in
spected, not once, but many times.
An imperfection may mean that
boat costing thousands of dollars is
worse than valueless.
The responsibility for the quality of
parts and for the quality OF the out
put is placed in the inspection sec
tion, engineering department, which
has a corps of 125 inspectors, each
passing on the quality Of some part
at one stage in production. Every
one Of the $4,000 screws is inspected
after II has been sunk in the wood.
Each wood part is inspected many
times to detect the presence Of pitch
pockets, knots. spiral grain or any
one of many defects that may reduce
strength.
Ordinarily only a little more than 5
per cent of the wood in a tree is good
enough to become a part of a sea
plane. Take, for example, a longe-
ron longitudinal beam of the hulD.
The boat of a seaplane depends for
shape and strength upon its keel and
lonEerons. On each side of the keel
or backbone Of the boat are two lon
gerons. These lengthwise strips OF
wood correspond to gunwales. and
therefore must be strong. tough,
straight-grained and easily bent in
shape.
Select Best White Ash.
Ash has been found most suitable
for this purpose, and from The forests
of New York and northwestern Penn
sylvania comes the ash used in these
seaplanes. Government inspectors
visit the lumber yards in these States
and select the best white ash, reject
ing most of that which is offered.
That selected is known as second
growth or wood which has grown
rapidly and has therefore wide rings,
such as one finds in young thrifty
timber with plenty OF room for de-
velopment. II is, however, impossible
to obtain suitable ash in fifty-foot
lengths, so the longerons must be
made I'D of several sections spEced
together.
After reaching the navy yard the
ash is inspected as it is unloaded. As
needed the lumber is brought to the
factory, and sawmill men rough il to
size. 1t is then placed in the hands
of skilled cabinetmakers and furni-
ture factorymen. These men run it
through molds to obtain the shape
needed. An inspection OF each indi-
vidual piece follows.
II flaws have been uncovered by
previous operations the inspector
must determine what use other than
the one originally specified can be
made of the material. Approximate
lengths are cut OF with allowance for
bending and the ends are then ta-
pered. A careful inspection is made
TO determine the correctness of the
sizes and to reject any, material not
in exact accordance with the specifi-
cations. All pieces to be used are
treated to a coat of wood filler.
Steamed Until PIIabIe.
Sections of the pieces to be shaped
are steamed until soft and pliable
then cIamped to a form and remain
there until dry. When removed. they
are again inspected for any possible
compression failure or buckling OF
the fibre. Those that are found sat
isfactory are fitted together with
scarf joints, which arc white loaded.
riveted and reinforced with wrapping
Again the forward end Of the long
.eron is steamed. and while still plia-
BILE the Iongeron is fitted into place
and given the necessary curve at tho
bow. The final inspection does not
occur until the longerons are in place
and dry.
Similar care is exercised with every
other wood part and with every
metal part As further example.
take tuc care in tho preparation 90
one metal fitting. Across the 4, .
Of tha S'aplBno'S boat II n sidewalk.
A Liberty motor rests on each end
OF this sidewalk and below hangs the
outer section OF q wing. But the