1、BRITISH STANDARD BSG123:1949 Specification for Aircraft magnetic compass remote-reading (non-stabilized) NOTEThe Institution desires to call attention to the fact that this standard is intended to include the technical provisions necessary for the supply of the material herein referred to, but does
2、not purport to comprise all the necessary provisions of a contract.BSG123:1949 This BritishStandard, having beenapproved by the Aircraft Industry Standards Committee and endorsed by the Chairman ofthe Engineering Divisional Council, was published under theauthority of the General Council of the Inst
3、itution on 15December1949 BSI 02-2000 ISBN 0 580 34523 8 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from leg
4、al obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front
5、cover. Amendments issued since publication Amd. No. Date CommentsBSG123:1949 BSI 02-2000 i Contents Page 1 Definition 1 2 General construction 1 3 Detailed construction 1 4 Supply 1 5 Accuracy 1 6 Vibration 2ii blankBSG123:1949 BSI 02-2000 1 Preferred size: BritishStandard aircraft instrument case,
6、Type1. Preferred units of graduation: Angular degrees. 1 Definition For the purpose of this BritishStandard the term “remote-reading magnetic compass (non-stabilized)” denotes an instrument comprising a master magnetic compass or detector and one or more indicators remote from the detector which sho
7、w the heading of the aircraft relative to the magnetic meridian, the system not employing a gyroscope either for stabilization or for smoothing of indication. 2 General construction The construction of the instrument shall be mechanically sound, suitable for its purpose, and in accordance with the r
8、equirements laid down in BSG100, “General requirements for indicating instruments and electrical apparatus” 1)with respect to climatic proofing, temperature performance, and ability to withstand aircraft vibration. 3 Detailed construction a) The detailed construction of the units shall be in accorda
9、nce with relevant requirements laid down in BSG100. b) The instrument shall consist of a magnetic compass, or detector (master unit), designed for mounting in the most suitable magnetic location in the aircraft. Means shall be provided for transmitting its indications to a suitable repeater or repea
10、ters mounted in the instrument panel, or at any station in the aircraft. c) The general construction of the master unit shall be of non-magnetic materials with the exception of the magnets or the direction-sensitive elements. d) Any fluid or electrolyte, if used, shall not re-act with any of the mat
11、erials with which it is in contact. Provision shall be made to accommodate volumetric changes of the liquid throughout the temperature range 70 C. to+70 C. e) Suitable provision shall be made for isolating the magnetic element from excessive aircraft vibration. f) In the case of master units employi
12、ng pendulously pivoted magnets, the pendulously of the system shall be such that the change of one oersted of vertical force at London results in a change of tilt not in excess of3degrees. The damping of the directional element and its magnetic characteristics shall be adjusted to promote maximum st
13、ability under all conditions of flight. g) The instrument shall function satisfactorily when tilted through any angle up to and including20degrees. h) The repeater shall be accurate in accordance with an approved presentation, which may consist either of a vertical dial with a moving compass card or
14、 a vertical dial with a moving compass pointer. The repeater shall be provided with a course-setting device readily adjustable from the front of the instrument. The repeater dial shall be accurately divided in units of2degrees or5degrees according to the size of the dial. The treated dial markings s
15、hall satisfy the requirements of BSG100. i) Means shall be provided for correcting the deviations of the compass. 4 Supply The instrument shall operate either on a nominal supply of24volts D.C. or400cycles,115volts A.C. 5 Accuracy a) The following performance requirements shall be maintained with no
16、minal power supply of24volts D.C., normal field strength at London, and throughout the following temperature range: b) Master unit. The directional error of the master unit on any heading shall not exceed the following values: 1: degrees with the master unit horizontal. 1 degrees with the master uni
17、t tilted10degrees. 2 degrees with the master unit tilted15degrees. 3 degrees with the master unit tilted20degrees. c) Repeater. The error of the repeater indication when checked against a calibrated master unit on any heading shall not exceed 1; degrees. 1) In course of preparation Magnetic detector
18、 unit, 70 C. to+70 C. Other units, 20 C. to+50 C.BSG123:1949 2 BSI 02-2000 d) Combined transmission error. The maximum combined transmission error of any master unit and repeater of a given type, as indicated by the repeater pointer, shall not exceed2; degrees irrespective of the direction from whic
19、h the heading is approached. e) Sensitivity. The master unit shall respond to a minimum change of course of: degree when operating on normal supply voltage. The value corresponds of the “dead sector” and shall be not greater then2 degrees when the instrument is operating at any supply voltage within
20、 the specified range. f) Follow-up. The repeaters shall follow the master unit accurately at any rate of rotation up to20degrees per second and shall not become permanently de-synchronized at any speed of follow-up of which the system is capable. g) Friction error. The friction error shall not excee
21、d2degrees, and shall be defined as the angular distance between the two settling positions after deflecting the magnetic system10degrees to each side of the meridian in turn. The instrument shall be kept free from vibration during the test. 6 Vibration The instrument shall show no errors outside the
22、 tolerance specified in Clause5 when subjected to the varying frequency vibration tests relevant to its installation position in the aircraft (which may be the wing tip) laid down in BSG100, and any pointer oscillation shall be within the limits permitted therein. The instrument shall also withstand
23、 the appropriate endurance vibration test laid down in the same standard without damage or derangement.blankBSG123:1949 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on
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