Figure 3-17.--Gulide slope indicator, simplified functional diagram.

At the same time the cell is focused it can

Thus, the cell can be focused and the sensitivity set

be calibrated for proper glide slope. Referring to fig-

by moving the light source and slots in relation to the

colored filter (fig. 3-17). In the GSI cell, the distance

ure 3-19, you can see that the same screen arrangement

from the slots to the Fresenel lens is 16.8 inches. The

can be used for measuring the angle of the red/amber

cell is calibrated so the 1-inch amber section of the

inter- face.

lenticular lens is exactly 1 degree of arc. A typical cell

Set the baroscope supplied with the system on top

calibration setup is shown in figure 3-18.

of the level plate and mark off a reference mark on each

To focus the cell, it must be placed on a level plate

screen. Adjust the cell glide angle using the knurled

and two screens 10 feet (1/8 inch) apart must be set up

knob under the lamp housing until the difference be-

in front of the cell (see fig. 3-18). Turn the cell on and

tween the reference mark on the red/amber interface on

measure the height of the amber at screen one and

screen two is equal to 6-9/32 inches 7/32 inch. Drill

subtract it from the height of the amber at screen two

and pin the degree plate so it indicates three degrees.

(fig. 3-19). If the cell is properly focused, the difference

should be 2-3/32inch1/8 inch. A dark band will appear

In this measurement, the cell should project the

between each of the colors due to light scattering at the

beam on the two screens and the center of the dark band

interface; this band should be split evenly to obtain

between the red and amber filter should be used for all

height measurements.

measurements.

The slot through which the light bar is formed

Beam Angle

determines the size of the light bar as it is viewed

through the cell face. In this system, it is not adjustable.

The angle of the light beam to the horizon must be

accurate and remain constant so a pilot may maintain a

THERMAL CONTROL

fixed rate to the ship. The glide slope angle is set using

the degree plate on the right side of the cell and is

Temperature control of the GSI includes cooling

checked on-the platform by means of pole checks to

of the projection lamp compartment and temperature

ensure the proper settings.

Figure 3-17.--Gulide slope indicator, simplified functional diagram.

3-12