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| MlL-T-81333A(OS)
3.2.1 Mechanical requirement The telescope shall be constructed to have the eyepiece in a horizontal plans
parallel to the plane formed by the horizontal mounting fast on the bottom of the instrument. The line of sight shall
be capable of being elevated 95 defrees above this plane and depressed 25 degrees below the same plane. Move-
ment of parts involved in the operation of the telescope shall be positive,accurate, free from excessive friction,
and shall not transmit shock of jar to optical elements of their monts. Operaating knobs and levers shall be capa-
ble of being adjusted by gloved hands.The mirror and its assembly shall be so balanced as to maintain and hold
its position for any setting between the limits of elevation specified for environmental conditions set forth herein.
The torque required to turn the elevation mirror adjusting shaft shall not exceed 5 inch-pounds
3.2.1.1 Limit stops Limit stops shall be provided to prevent derangement of mechanisms. The travel of the
line of sight of the telescope shall be limitedby such stops, one stop being set at + 100 degrees (elevation) and
the other -30 degrees (depression).
3.2.1.2 Alignment of elements Means shall be provided for checking, aligning, and adjusting all interrelated
elements of the telescope.
3.2.1.3 Headrest and support Each telescope shall be fitted with a headrest support similar in principle to
that shown on Drawings 510543 and 510544. On this support shall be mounted the soft rubber headrest shown
on Drawing 511050 (see 37).
3.2.1.3.1 Eye buffer. Each ocular shall have provisions for mounting a soft rubber eye buffer or eye guard as
specified in MIL-F-18870. Eye buffers or wyw guards shall be supplied by the contractor.
3.2.1.4 Metallic parts and materials. The main body casting shall be of copper alloy No. C92300, in accordance
with QQ-C-390. Other metal parts shall be of brass or bronze, in conformance with specifications listed on LD167920
or LD412526 as applicable unless permission is obtained from the conrtacting activity for the use of other material
which may be satisfactorily substituted. The selection of dissimilar metals for use in construction of the telescope
shall be made to minimize corrosive action caused by electrolyte action between the metals forming a galvanic
couple. Possible galvanic couples and the degree of corrosive action associated with each are listed in MIL-E-16-400
3.21.4.1 Non-metallic parts and materials. Non-metallic parts and material used in the construction of the
telescope shall be in accordance with the drawings and specifications listed on LD167920 or LD412528 as applica-
ble and as specified herein. Materials which are nutrients for fungus shall not be used in applications other than
those approved in MIL-STD-454 unless prior approval of the contracting activity has been obtained. Nutrient materials,
when used, shall be treated in accordance with MIL-T-152
3.21.5 Lens mountings. All lenses shall be secured by means of screwed-in retaining rings, with lock rings
or set screws. "Spinning of beating metal over the edges of lenses will not be acceptable. The objective lens
shall be provided with a double eccentric mount for collimation.
3.2.1.6 Screws. All screws shall conform either to FED-STD-H28 or to those shown on Drawings 8-Z-1008 to
8-z-1021. All threaded parts shall conform to FED-STD-H28 as regards pitch, form, and size of thread.
3.2.1.7 Finish. All external metal surfaces, except for mounting surfaces, shall be covered with two (2)
of light gray enamel in conformance with MIL-E-1509Q Operating knobs handles, etc, shall be covered with a
durable black baked lacquer, system no. 9, in accordance with MIL-SD-1303
3.2.1.8 Reference designations and markings. All parts of the telescope shall be marked as shown on ap-
plicable drawings listed in LD167920 or LD412528 as applicable and as specified herein. Markings shall include
an identification plate affixed on the surface of the central portion of the telescope In lieu of the identification plate
such data as would be contained therein maybe engraved on the exterior of the body casting provided precau-
tions are taken to proect the engraved figures and numbers from being defaced by corrosion or subsequent paint-
ing of the telescope. Identification will not be required for glass components.
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