July-August - Air Defense Artillery School

Shadowgraph for Recognition T rainingl
By Lieutenant J. F. Carson, Coast Artillery Corps
One \\"eakness of most systems of aircraft recognition instmction
in which projected pictures are used is the fact
that too much detail is exposed to the student in pictures
of planes which he is required to identify. As a consequence,
the student will, perhaps unconsciously, memorize
certain detailed features peculiar to each plane. These
features will be used as a crutch at first and if the tendencv
is not checked, all other features of the plane will slip back
out of memorv. The student has then lost all contact with
the goal of re~ognition training; the learning and retention
in the mind of the total fonn of the aircraft.
To assist in the correction of this deficiency, a simple device
has been constmcted which will, to a large degree,
simulate the appearance of an aeroplane in the sky. It is not
used to replace any of the present methods of recognition
training but rather as a supplement to current equipment.
It has been found to be an effective adjunct to learning and
it adds interest to the classroom work. This device is known
to most as a Shadowgraph and can be constructed in a number
of ways. A successful constmction, devised at Camp
Edwards, is shown in the accompanying picture.
DESCRIPTION
The box is 18" wide by 24" long and 16" high at the
rear where it rests on two 6~" legs. The front is deeper,
22W', due to the sloping bottom of the box. At the bottom
front is a 6" by 6" light chamber which extends all the way
across the front and houses a socket with a 200-watt bulb.
Between the light chamber and the inside of the box is a
tin bulkhead. A 2" round hole is cut in the bulkhead to
allow the light from the bulb to enter the main box. The
bulge of the light bulb should be placed immediately in
front of this hole and as close to the bulkhead as is possible
without touching. The dimensions of the hole and the
placement of the bulb are most important as they provide
the point source of light required to prevent a double
image. \Vithin the main box and directly over the bulkhead,
a balle is installed to prevent light from shining di-
rectly upon the screen. This balle is 6" deep and extends
across the full width of the box at the front. An 8" high
bv 10" wide mirror is centered in the rear of the box and is
hinged at the bottom. A stiff wire is attached to the top rear
of the mirror frame and projects through the rear of the
box so that the angle of the mirror mav be readily adjusted
as required. The mirror reRects the light from the light
THE FOCKE-WULF FW 190A3
Assemb[y Instructions
1. Bend wings (A) at the center line and insert sideways in
the fuselage (B) through slot (A 1).
2. Take cross-section (C) and insert in slot (C) of the fuse-
[age and slot (C2) of the wing section.
3. Bend forward the wing supports of (C) so that the tabs
sl~p into the appropriate slots at the extremities of the
wmgs.
4. Insert section (0) in slot (Dl) of the fuselage and through
s[ot( 02) of cross-section (C).
5. Insert tai[plane (E) in slot (El) of the fuselage.
6. Insert cross member (F) in slot (F 1) of the fuselage.
7. Insert cross member (G) in slot (G 1) of the fuselage.
Note: In certain front and rear aspects of the assembled rno dd
better results will be achieved by bending section (0) upwards
so that it touches the tail plane.