The Norden Bomb Sight manual

D. Failure

to Erect

Fore and

Aft Hair

Properly.

Even with the stabilizer misaligned,

is zero drift, that

is, if the transverse axis of

the bombsight case is

exactly at 90° to the

and aft axis of

stabilizer, there

will be no

tilt in the optics.

If the stabilizer is misaligned, when the

fore and aft hair is

made parallel to the

and aft axis of the plane, there

will be a drift

reading.

course,

result in a tilt in

And the presence of drift wil This

the optics.

tilt, which should not be present, will

deflection error.

If the stabilizer is misaligned clockwise,

the bottom of the aptics wil be toltecto the

Left and the deflection error mill be to the right

If the stabilizer is misaligned counter clockwise

the bottom of the

..optics

..will betited to the

right and the deflection error will be to the left.

If the fore and aft hair does not rest in the

vertical with zero drift and zero trail in the

C. T. mechanism,

a deflection error will occur.

This would

the gyro rested

in the true vertical at the

time the hair was

being erected.

If the gyro were out of the true

vertical in the same direction and

for the same

amount that the fore and aft hair was improperly

erected, then

there would be no cause for a de-

flection error.

One of the most common causes for improper

erection of the fore and aft hair is failure to

have the reflecting surface level.

Even though the

fore and aft halr were er-

ected

to the vertical with zero drift and zero

trail in the C.T. mechanism and while the gyro was

in the true vertical, if at this time the trans-

verse bubble is not centered, a bombing error is

bound to occur in actual operation of the sight.

This

is true as long as

the leveling bubbles are

used

is no automatic erection system

capable of constant operation. The student should

be able to state the kind

of bombing error which

would occur; first, if the transverse bubbie in

if

there

fore

the

fore

This

cause

a

be

true

even

though