1、BRITISH STANDARD BSG122:1949 Specification for Aircraft magnetic compass Remote-reading (gyro-stabilized)BSG122:1949 This BritishStandard, having been approved by the Aircraft Industry Standards Committee and endorsed by the Chairman ofthe Engineering Divisional Council, was published under theautho
2、rity of the General Council ofthe Institution on 15December1949 BSI 02-2000 ISBN 0 580 34522 X 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
3、not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the
4、 amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSG122:1949 BSI 02-2000 i Contents Page 1 Definition 1 2 General construction 1 3 Detailed construction 1 4 Operating conditions 2 5 Accuracy 2 6 Vibration 2ii blankBSG122:1949 BSI 02-2000 1 Preferr
5、ed maximum size: Designs incorporating a gyroscope of the direction indicator type for mounting on the flight instrument panel. Fixing holes: Four fixing holes spaced4.75in. vertically and4.5in. horizontally. 1 Definition For the purpose of this BritishStandard the term “remote-reading magnetic comp
6、ass (gyro-stabilized)” denotes apparatus for indicating the heading of the aircraft, utilizing the magnetic meridian as a datum, of the type in which virtually dead-beat indications are obtained on a master indicator (and repeater indicators, if any), by gyroscopic means, whether by stabilizing the
7、magnetic detector element or by employing this element to monitor the gyroscope or the transmission therefrom. 2 General construction The construction of the instrument shall be mechanically sound, suitable for its purpose, and in accordance with the requirements laid down in BSG100 “General require
8、ments 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 apparatus shall be in accordance with the relevant requirements laid dow
9、n in BSG100. b) The apparatus shall have a magnetic detector element designed for mounting in a favourable magnetic location, e.g.the wing or tail of the aircraft, and capable of transmitting data to an indicator or indicators suitably placed in the aircraft. c) The combination of the magnetic eleme
10、nt, gyroscope and transmission system shall be such that errors due to acceleration or attitude of the aircraft are effectively reduced, thus affording a sensibly dead-beat and accurate indication on compass indicators provided in the system. d) The apparatus shall be driven electrically. The power
11、supply shall be400cycles,115volts. A.C.nominal. Alternatively or additionally, D.C. power may be used from a nominal24-volt supply. e) The gyroscope shall start and run at a power supply of80per cent of normal voltage. f) The gyroscope shall possess a freedom of 85 in pitch or roll. g) The control p
12、recession rates of the gyroscope shall normally be not more than8 per minute and should be as low as possible consistent with a high degree of reliability. h) In systems which utilize a directional gyro, provision shall be made for switching off the monitoring control at will. Indication shall be gi
13、ven of absence of monitoring control due to switching off or to failure of control in normal operation. A switch shall be provided to isolate the monitoring system leading the power supply to the directional gyro unit alone. In systems which utilize a vertical gyroscope, means shall be provided for
14、clamping the gyroscope in the normal attitude for level flight and an indication of this condition shall be provided for the pilot. j) The course indicating dial(s) shall be calibrated over a range of360 azimuth with markings at the intervals shown below, according to the size of the dial: The treat
15、ed dial markings shall satisfy the requirements of BSG100. k) A settable course-marker for the pilots compass dial shall be provided to indicate the course to be flown; and the preferred presentation shall be a vertical dial with a moving compass card. l) Means shall be provided for correcting the d
16、eviations of the compass. m) Electrical connections to instrument units shall be taken through suitable plugs and sockets, and the case shall either be hermetically sealed or provided with adequate filtered vent holes. Means shall be provided for preventing misting of the inner surface of cover glas
17、ses. n) The apparatus shall be so designed that shock loads, giving an acceleration of50g, in any direction, do not cause permanent derangement of the mechanism. Height 5: in. Width 5in. Overall length 8in. 1) In course of preparation. Navigators indicator, 1 or2 intervals. Pilots indicator, 2 or5 i
18、ntervals,BSG122:1949 2 BSI 02-2000 4 Operating conditions The apparatus shall function without derangement and to the limits of accuracy specified in Clause5 over the ranges of temperature and on the varying supply conditions specified in BSG100. 5 Accuracy The following performance requirements sha
19、ll be maintained with nominal power supply(400cycles,115volts,A.C.;24volts D.C.), and throughout the following temperature range: At nominal power supply conditions and earths field strength of0.18 oersted horizontal and0.43 oersted vertical component, the pilots indicator shall have no errors great
20、er than1; on any heading. At the extreme conditions of power supply and at field strength0.08 oersted horizontal and0.88 oersted vertical component, the errors shall not exceed3 on any heading. Corresponding errors at the navigators indicator shall not exceed1 and2 respectively. 6 Vibration The appa
21、ratus shall show no errors outside the tolerance specified in Clause5 when subjected to the varying frequency vibration tests relevant to its installation position in the aircraft laid down in BSG100, and any pointer oscillation shall be within the limits permitted therein. The instrument shall also
22、 withstand the appropriate endurance vibration test laid down in the same standard without damage or derangement. Magnetic detector unit, 70 to+70 C. Other units, 20 to+50 C.blankBSG122:1949 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body
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