The Norden Bomb Sight manual

determining this error,

and it is also in a posi-

tion

remove one-half of the error

with the

level

and the other

haif with

the

table.

when

the leve! has

been turned about 180°

the error in

the level is now not only equal with that in the

table but

they are the same and not opposite

errors.

If exactly one-half of the error were re-

with each

the level and one-half with the

tab the ieve! about 1800

then there would be no need of again turn-

4. The

be checked for accuracy

from time to time by

positioning it on a flat sur-

face and turned 180°;

level is accurate,

the bubbie should be off exactly the

in each case.

Always mark first position of levei

on table and always place on same spot when turn-

ing it 180°.

G. Level need of stand.

The aim is to make the plane of rotation

of the head of the stand exact y in the horizontal.

a. If it were not,

when the sight was

changed from one cardinal heading to another while

making precession

runs since bearings are not

the point of bearing con-

fect, this might result in different readings.

Many maintenance men omit this step

as one of minor consequence. However, it is brief-

ly accomplished and should be

included. One level-

ing can last for numerous calibrations.

H. Level Stabilizer.

bushing to the true vertical.

here is to erect the sight stem

a.

This step is necessary in connection

precession runs and in the division of back-

lash

using one of the reflection methods in

the erection of

cross hairs.

Wedge

Gyro in

The Vertical - -Procedure.

With no tilt in the C.T. mechanism, the

дУгО

and fore and aft hair should occupy the same

relative

position

to the vertical. This is because

the fore

and aft

hair should at all times be in

the vertical except for any tilt occasioned by the

C. T.

mechanism

independent of the gyro.

The gyro

is always retained in the vertical by centering

the gyro leveling bubbles--and it must then be

assumed,

if deflection

error is to be avoided.

that

fore and aft hair is also in the vertical

except as mentioned.

to

moved

ing

the

ievel

if

the

same

amount

1,

tact

would

be

changed.

Since

bearings

are

not

per-

b.

with

when

the