1、MIL-S-21639 (AER) 15 DECEMBER 1958 MILIIARY SPECIFICATION SEXTANT, BUBBLE AQlJ-l/A This specification has been approved by the Bureau of Aeronautics, Department of the Navy. Scope - The equipment covered by this specification shall be a tp of Bubble - 1. 1 Sextant, AQU-/A, for use in military aircra
2、ft. 1.2 Classification - The Bubble Sextant shall be of one type as specified h 6.4. 2. APPLICABLE DOCUMENTS 2. 1 General - The documents listed in 6.5, of the issue in effect on the date of invitation for bids, form a part of this specification. 3. REQUIREMENTS 3.1 Parts and Materials - In the sele
3、ction of parts and materials, fulfillment of major design objectives shall be the prime consideration. In so doing, the following shall govern: (1) Parts and materials as approved by Specification MIL-E-5400 shall be given first consideration. (2) When the characteristics of standard MIL parts and m
4、aterials are such that their use will not fulfill the requirements because of size, weight, performance or other reasons, material and parts shall be used which most nearly meet or exceed the requirements of the respective standard parts and material specifications. (3) When a nonstandard part is us
5、ed, the meeting of general material requirements such as nonflammable, fungus resistance, nontoxic, etc., and the meeting of environmental conditions as required by Specification MIL-E-5400 or MIL- T-5422 shall be of prime consideration. (4) In the selection of parts, the above considerations shall
6、apply if the assembly is to be built for detail part maintenance. In the event the entire assembly is built to be expended, the assembly shall be constructed and the quality of the . individual parts shall be such that the unit as a whole will pass material, elec- trical and environmental tests. Any
7、 assembly built to be expended must be approved first by the Bureau of Aeronautics. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MILS-21639 (Aar) 3.1.1 Nonstandard Parts and Material Approval - Approval for the use of nonstandard parts and materia
8、ls shall be obtained as outlined in Specification MIL-E-5400 except as follows: (1) Mechanical parts shall be submitted as nonstandard parts only when the material requirements of Specification MIL-E-5400. are not met. (2) Nonstandard parts of an electrical nature as defined in Specification MIL-E-5
9、400 must be approved before the preproduction model of the equipment is submitted for tests. The request for approval shall be forwarded to the Bureau of Aero- nautics before the part is purchased or fabricated. In adciition to or in lieu of the Nonstandard Part Data Sheet, the contractor shall subm
10、it an itemized list of the parts, their sources, and the contractors drawing or purchase specifi- cation covering the parts. 3.2 Design and Consk2ction: 3.2.1 General - The equipment shall conform with all the applicable requirements of Specilication MIL-E-5400 for design, construction and workmansh
11、ip, unless otherwise specified herein: mum consistent with good design and shall not exceed 19 pounds. 3. 2. 2 Total Weight - The total weight of the equipment, excluding cables, shall be a mini- 3.2. 3 Operating Life 3.2.3. 1 Reliable Operating Life - The equipment shall have a reliable operating l
12、ife of at least 200 hours without removal, for bench servicing. Parts requiring servicing or replacement at the end of this interval to renew this service life shall be specified bv the manufacturer. 3.2.3.2 Total Operating Life - The equipment shall have a minimum total operating life of 2OO hours
13、with reasonable servicing and replacement of parts, within this interval and the life of such parts shall be specified by the manufacturer. Parts requiring replacement 3.2. 4 Cabling and Connectio 3.2. I. 1 Cables and Connectors - The equipment shall provide for the use of cables and connectors in a
14、ccordance with Specification MIL-E-5400. 3.2.h. 2 Interconnecting Cabling - The equipment shall be capable of satisfactory operation using external wiring in accordance with the applicable requirements of Specification MIL-W-5088. The external wiring shall be unshielded, except that a minimum number
15、 of the individual wires may be shielded when demonstrated as necessary to meet interference control requirements, and provided the assembly of the cable to its plugs may be easily accomplished. External cables and that portion of the connectors attached to the cables shall not be supplied as part o
16、f the equipment. 3.2.1,. 3 Input Power Connections - Input power connections shall be in accordance with 3.2.5 MS 25245. Nomenclature and Nameplates - Nomenclature assignment and nameplate approval for equri-*-n+ idontifiratinn shall be in accordance with Specification MIL-N-18307. 3.2.6 interchange
17、ability - The equipment shall meet the interchangeability requirements as specified in Specification MIL-E-5400. Unless otherwise specified, interchangeability shall be measured against a model supplied by the Bureau of Aeronautics. 3.2.7 Maintenance Provisions and Field Testing - Provisions for mai
18、ntenance shall be as suecilied in Snecification ML-E-5400. Specific test ooints and test facilities shalI be Drovided to tie greatest extent practicable for ease offield testing and maintenance. performance characteristics under standard conditionc and for making Iaboratory bench tests. 3.2. 8 Stand
19、ard Conditions - The following conditions shall be used to establish normal Temperature Altitude Normal ground Vibration None Humidity * Room ambient up to 90% relative humidity Input power voltage Room ambient (30 I 10C) 115 i 1. O V AC and/or 27.5 I O. 5 V DC Provided by IHSNot for ResaleNo reprod
20、uction or networking permitted without license from IHS-,-,-MIL-S-22639 66 W 9999906 0230L137 3 W 3.2.9 Service Conditions - The eouipent shall operate under any of the environmental service conditions or reasonable combination of these conditions as s-pxified in Spcification MILE- 5400 for Class 2
21、equipmsnt except as spcified herein. 3.2.10 DC Power 2, and so designed that the bulbs axe easily replaced. The illumination of the presentation shall be such that the images axe clearly defined with minimum glare in the field, and shall permit adequate dimming of the illumina- tion for observation
22、of second magnitude stars. may be adequately illuminated for anycombination of outside bright daylight and inside dim aircraft illumination levels. 3.32.3.1 Bubble Liauid - The liquid used in the bubble level shall conform to Specification The illumination shall be such that the presentation MGF-556
23、2. Other liquids nay ue used if specifically approved by the Bureau of Aeronautics. 3-3.2.4 ODt ical Reouirements - The optical requirenents shall be as follows: (i) Ail lenses, prisms, and mirrors shall be of first quality, made from first- class stock and shall be accurately ground, polished, and
24、centered. optical system shall be well corrected for chromatic and spherical aberration. Lenses shdl be mounted free from strain. The exit pupils for the bubble and for the star field shall be concentric within 4 millimeters. The (2) (3) The eye distance for the star field and for the bubble field s
25、hall not differ by more than 12 millimeters. , 3 . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-M1L-s-a639(der (4) Minuta .Indicator, L The third rum shall contain numeral for each 5 mimifes of altitude fran O through 55. The height of these mnner
26、als shall be 3/32 inChe kadyation marks for eaoh tical cmponents. h suitable indicator shall also be povided to indicate the presence of moisture. (7) (8) After The light shall be visible in the field of the azimuth (U) 3.3.3 %ssure SoeJ - The mounting flange of the sextant shall be such that a suit
27、able pressure mal will be effected when the sextant is installed in the aircraft, hY gaskets, if necessary, shall be furnished with the sextant, 0p;Libratioo Card sextant with the following infarmation: (1) Sextant index error at three points, O, 45, and 90 (2) Tbe date of collimation of the sextant
28、. Cover Elah A suitable cmr plate shall be furnished under a separate part number to effeot a pree however, it may be reworked by the contractor and submitted for accep tance as a production equipnent. No production equipents shall be Prefabrication of production equipmnt The preproduction model sha
29、ll not be considered as one of the The approved pre- 4.3 Acceotance Tests - The contractor shall furnish all samples and ehall be responsible for accomplishing the acceptance tests. Al1 inspection and testing shall be under the supervision of the Government Inspector. Bureau of Aeronautics shall eng
30、age the service of a comercial testing laboratory acceptable to the Bureau of Aeronautics. acceptance tests. laboratory, as applicable. Acceptance or approval of material during the course of manufacture shall not be construed as a guarantee of the acceptance of the finished product. Acceptance test
31、s shall consist of the following: Contractors not having testing facilities satisfactory to the The contractor shall furnish test reports sharing quantitative results for all %ch reports shall be signed by an authorized representative of the contractor or (1) Individual Tests (2) Sampling Tests (3)
32、Special Tests Individual Tests -Each equipent submitted for acceptance shall be subjected 4-3.1 and satisfactorily pase the following tests conducted as specified in 4.4. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-(1) Bbrapiination of Froduot
33、(see 4.4.2.1) (2) Soale Error (see 4*4,2.2) (3) (4) Shade Glass (see 4.4.2.4) Bibb10 Cell Curvature (see 44.2.3) (5) Fixed Setting (-0 4*4*2*5) (6) Slippsge (see 4,4.2*6) (7) Continuaualy Changing Settings (aaqembled sextant) (see 4.4.2.7) (8) Variable Time Amrager (VTA) - zero adjustment (see 4.4.2
34、.8) (9) Variable Time Amrager (WA) - mro setting (see 4.4.2.9) (10) Variable Time Amrager (WA) - backlash in averaging mechanisin (11) Maxianm Opration Period (see 4.4*2*11) (12) Dieleotric Strength (see 4.4.2*12) (13) kimuth Mscheiem Performance (see 4.4.2.13) (BOO 4.4*2.10) 4e3.2 Camrilitw Test -
35、Sampling tests sball be conducted on equipnts whioh have uccasafly pnased the tests of 4.3.1; The follwing quantity of equipnents shall be selected by the Governunent Inspeotor far samping kstsr Quantity of quipents Offered for bcCtrtanCQ Quantity to be Testea First IO 1 11 to 100 2 101 to 200 1 hr
36、200 1 for eaoh additional 200 or fraction thereof 4r3.2.l SCOUI of beta - b a minimum, each equipnt seleoted for sampling tests (1) Vibration Error Test (2) (3) Notdogging (4) ;zumination (5) Counter shall b subjected to the following teeta oonducted as specified in 4*4. Sextant and Jhbble Cell Temp
37、erature 4.3 b3 Swcial Test w Special teats shall be conducted as determined by the aireau of Aeronautics on a quantity of equi she sextant lhe heading shall be checked each Wo frm Oo Total error 4.4.2-3 Bubble Cell Curvature Test - Each sanple sextant shall be tested for correc- tions of bubble cell
38、 curvature. The error due to incorrect curvature of the bubble cell shall not exceed 2 minutes of mo at any point along the line of sight up to 2f3 of the distance from the center to the edge of the bubble field. 4-11-24 Shade Glass Tes - Each sample sextant shall be tested toetermine the error caus
39、ed by the shade glasses. The use of any shade glass shall not introduce secondary images or deviation in excess of 30 seconds of arc along the line of sight or 3 minutes in a plane perpendicular to the line of. sight. time between 1 and 2 minutes on any dtitude setting with the hob held stationary.
40、Movement of the primary indicating element shall be not more than 0.01 inch. using different operating periods and drum settings, arbitrarily chosen. 4.4-2.5 Fixed Settira Test - The averager shall be operated for any desired period of This test shall ba perfQrmed three the 4.4.2.6 SliDlXlEQ - The a
41、verager shall be operated for the naxirmmi possible th in- terval and the altitude setting noted after bringing the indices into coincidence. the niechanism, the knob shall be rapidly oscillated 5 fron its setting. After a minimum 5 cycles, the indicator shall be brought into coincidence. not differ
42、 from that previously obtained by more than 2 minutes of arc. backlash from this test, both eltitude readings shall be obtained as the primary element of the averagr ing indicator is brought into alignment by rotation of the knob in the same direction as that of the start of the cycles. operated for
43、 any desired period of time during which the altitude settings change continuously and at a constant rate, through a range of not more than 2.5 degrees. averager shall agree with the average of the initial and final altitude settings to within the following: Without rewinding The altitude setting th
44、en obtained from the averager shall To eliminate the effect of This test may be combined with other tests if desired. 4.4.2.7 Continuously Changing Settings (Assembled Sextant) - The averager shall be The average altitude computed by the : Provided by IHSNot for ResaleNo reproduction or networking p
45、ermitted without license from IHS-,-,-At the end of 30 seconds, 5 5 minutes of arc; At the end of 1 ninute, 9 minutes of arc; and At the end of 2 minutes, y2 =inutes of arc. This test shall be performed five times using different operating periods and altitude settings arb%- trarily chosen. At least
46、 one test shall include initial and final drum settings differing iJr approxi- mtely 2.5 degrees, 4.4.2.8 rewound, and before the averaging mechanism is put into operation, oscillation of the knob through loo range of reading shall not move the element of the averaging indicator more than 0,Olinch f
47、or a wries of 5 or more cycles. opratad for a cmplete cycle of operations, it shall be rewound. When rewound, the indicator shall return to within 2 0.01 inch of its zero index mark. inatrumnt has run for the maximum th interval and before it is rewound, backlash in the averaging nechatisim shall be
48、 determined by bringing the indicating elements and the index marker into coincidence fhst from one direction then from the opposite direction and noting the remlting sextant altitude readings. These readings shall not differ by more than lminute. To eliminate the effect of slippage dl oprations of
49、this test shall be done slowly. kimUm bratinrt %riod - The averager shall be operated three times for the maximum tin10 interval. The length of time of each auch period shall be 2 minutes j$ seconde. This bet nay be combined with other tests if desired. 4*4*2r12 Dielectric Strenrth -With the lampa removed and bubble disconnected, the aextant ahdl be subjected to a high potential test. !i salecrustat,ions, the sextant shall be subjected to the individ
