The Norden Bomb Sight manual

the

telescope quadrant at exactly zero,

the trans-

verse hair should

be exactly zero. This relation-

ship must exist because otherwise the position of

the telescope quadrant from its

zero degrees set-

ting will not be exactly the

same as the sighting

angle in degrees.

And this would mean

range errors.

2.

To displace

the transverse hair:

a.

it has been

best to leave the

rate end on,

remove the

inspection plate, and

slightly rotate

(open) the

optics until the screw-

driver can reach the eccentric screw.

K.

a the rection of Erther Her te The

Vertical.

First there is the image of the lower

portion of the telescope

tube.

(Use rear image for

models later than M-3). This image is always

found upon the precision

a line drawn perpendicular to the precision mirror

from the lower portion of the telescope tube (or

its reflection

the rotating mirror in the

case of models later than M-3) intersects the pre-

cision mirror.

b. Second,

there is the matter of aiming

along the

hair in exactly the same manner

aims a gun.

The cross hair is analogous to

the front gunsight.

It is not reflected.

(1)

There are here two points of

reference: (1) the position of the eye and (2)

the position

of the cross

hair.

The eye should

be positioned

along the axis of

the telescope tuber

Peep sights are used to facilitate this.

and aft cross hair is positioned by tilting the

optics laterally; the

transverse

cross

hair is

positioned by opening and closing the optics.

(a)

In this paragraph, the dis-

cussion

limited to the M-3 and earlier

series.

telescope tube will be moved about

until the line of sight established by the posit-

ion

the cross hair

being erected exactly divid-

When this is finally accomplished,

telescope tube will be found to be at right

• hair has then

been erected

to the vertical--PROVIDED the pre-

cision

mirror is horizontal.

Suppose the pre-

mirtor was not horizontal.

The telescope

tube will still take a final position at right

angles to the surface of the precision mirror.

BUT naturally it will not then be in the vertical,

Two

Things

Must

Be

In

Proper

Relationship

To

Each

gther

In

The

Erection

Of

Either

Hair

To

The

a.

mirror

at

a

point

where

from

cross

es

the

image.

the

angies

to

the

mirror.

cision