This particular apparatus can be adapted to any equipment for training in antitank shooting.
The following description, and the accompanying sketches taken from British sources, are
based on the adapting of a "mock-up" 2-pounder (40-mm) antitank carriage which had originally
been fitted with an aiming rifle and telescope. The apparatus, however, can be modified to
fit on the barrel of a 2-pounder gun or any other equipment to suit particular circumstances.
The spotlight device consists of a flat metal bar on which a tube is mounted with a
lamp box fitted at the rear end. The box houses a 6-volt bulb, and its inner face is
pierced with a pin hole to allow the light to pass through the center of the tube. The
tube is adjustable for deflection and elevation.
The opposite end of the tube is provided with an adjustable carrier fitted
with a lens; by this means the spotlight is focused. Any suitable lens
available, can be used. The length of the tube should be such that the distance
from pin hole to lens is approximately equal to the focal length.
Two press switches should be included in the circuit in parallel, one operated by
the firing mechanism and one by the instructor. The details of the target and the
alignment of the spotlight are described below, with details of construction shown
in the accompanying sketches.*
a. Target and Frame
The target frame is rectangular and is approximately 7 ft. long and 5 ft. deep, but
any suitable means of carrying the target and of providing a background
may be utilized. The corners are cross-battened, and wood supports are
fitted to the bottom corners.
A metal rail 1 in. by 1/8 in. and about 9 ft. long is fitted between the
uprights of the frame, the flat side of the rail being vertical. The rail
is bent horizontally and forms a track for the target. If desirable, one
end of the rail may be slightly higher than the other (say 6 inches).
Wire hooks are soldered at varying intervals along the rail to act as
guides for the endless towing cord. The towing cord runs over pulleys
fitted to the uprights of the frame, a winding handle being fitted at one end.
The target carrier is made from a piece of light sheet metal 5 1/2 in. by 4 1/2 in., on
one side of which is mounted a model tank also cut out from light sheet metal, and
about 2 in. by 1 in. by 1/2 in. when made. On the other side of the carrier a
balancing weight is fitted.
The target carrier is suspended from a bogey which is pulled along the rail. The two
ends of the towing cord are attached to the bogey and pass around a small winch gear
by means of which the movement of the carrier is controlled.
The target carrier should be finished with light-colored paint, while the
tank itself is painted white, which is the most suitable color for showing
up the spot of light.
A back cloth of burlap, with a landscape painted on it, may be fitted to the rear of the target.
b. Setting Up
The spot-light apparatus is fitted on the mock-up or gun, and the circuit
wired up to a battery or small transformer.
The target frame is placed about 10 feet in front of the telescope.
c. Alignment and Focusing of Spotlight
The target is moved along the rail to the point which is nearest the telescope. It should
be so arranged that the tank is now at right angles to the line of sight through the telescope.
The "lead" screw should be placed in the center of its run.
The telescope is set to the chosen minimum "range," say 300 yards, and
aligned on the center of the tank, by using the elevating and traversing
The spotlight is switched on and adjusted so that the spot appears on the
center of the tank and sharply in focus. This is done by moving the adjusting
screw on the mounting, at the same time moving the lens carrier backwards or
forwards until the spot is seen to be clearly defined and as small as
possible. To obtain the best results the filament of the bulb, the pin
hole in the lamp box, and the center of the lens should be correctly
aligned. As the lens and pin hole are in fixed alignment, the lamp socket
should be fitted in such a way as to permit of a small adjustment of the
bulb to enable the filament to be correctly positioned.
When the spotlight is focused on the tank at the nearest pointy the tank is run to
that part of the rail farthest from the telescope. The "range" to this point is
obtained by bringing the spotlight on to the tank, using the elevating gear. The
line of sight through the telescope is then brought on to the center of the tank. This
will now show the "range" to the tank, which should be about 900 yards.
d. Control Gear for Lead
In use, the instructor offsets the spotlight for deflection by means of
the "control gear for lead" to render necessary the application of lead
when laying through the telescope.
* The specific materials referred to in the sketches and text, such as brass and mild steel, are
not necessarily the only suitable kinds.