1、BRITISH STANDARD BS G125:1950 Incorporating Amendment Nos.1 and2 Specification for Turn and slip indicators for aircraft purposes 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 here
2、in referred to, but does not purport to comprise all the necessary provisions of a contract. UDC 629.13.054BSG125:1950 This BritishStandard, having been approved by the Aircraft Industry Standards Committee, and endorsed by the Chairman ofthe Engineering Divisional Council, was published under theau
3、thority of the General Council of the Institution on 7June 1950 BSI 02-2000 ISBN 0 580 34524 6 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
4、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
5、 amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue Comments 1149 March 1951 1570 February 1953 Indicated by a sideline in the marginBSG125:1950 BSI 02-2000 i Contents Page 1 Scope 1 2 Definitions 1 3 General construction 1 4 Detailed construction 1
6、 5 Accuracy 2 6 Marking 2 Table 1 2ii blankBSG125:1950 BSI 02-2000 1 Preferred size: BritishStandard aircraft instrument case. Type1 of BS G100 1) , “General requirements for indicating instruments and electrical apparatus for aircraft.” 1 Scope This BritishStandard covers two types of instruments w
7、hich are calibrated for nominal air speeds of140 and280knots respectively. 2 Definitions For the purpose of this BritishStandard, “turn and slip indicator” shall denote an instrument embodying two separate mechanisms, each with an indicating pointer (or its equivalent), with separate scales on a com
8、mon dial. The “turn” pointer shall indicate rates of turn of the aircraft about the true vertical; the “slip” pointer shall indicate deviations from correct bank. 3 General construction The construction of the instrument shall be mechanically sound, suitable for its purpose, and in accordance with t
9、he requirements laid down in BSG100 1)with respect to climatic proofing, temperature performance, and ability to withstand aircraft vibration 4 Detailed construction a) The detailed construction of the instrument shall be in accordance with the relevant requirements of BS G100 1) . b) The “turn” mec
10、hanism shall preferably consist of a dynamically balanced gyroscope spinning about a horizontal axis in the YOZ plane of the aircraft, the gyroscope being carried in a gymbal ring, mounted in the case or frame of the instrument, in bearings parallel to the OX axis of the aircraft. The motion of the
11、gymbal ring relative to the case shall be spring-controlled and damped, and this motion shall be communicated to the “turn” pointer in such a manner that turns of the aircraft to the left shall cause pointer deviations to the left. c) The direction of rotation of the rotor and the stiffness of the s
12、pring system shall preferably be such that during banked turns, at constant height and at the nominal air speed for which the instrument is designed, the spin axis of the gyroscope remains substantially horizontal and, hence, turns are measured about the vertical. d) The rotor of the gyroscope shall
13、 be designed to operate on one of the following: i) 24volts D.C. power supply, consuming not more than0.2amp. In this case the rotor shall preferably be fitted with a governor effective over the range2030volts. ii) Alternating current400cycles, with a maximum consumption of10VA and a power factor of
14、 not less than0.8. iii) Suction at3 1 / 2 in. of mercury with a maximum consumption of0.25cu. ft. of free air per minute. e) At normal temperatures the rotor of an instrument operating on D.C. supply shall start when6volts is applied, or a suction-driven instrument when0.5in. of mercury is applied.
15、f) In suction-driven instruments blockage of the driving jet shall be prevented by the fitting of an efficient and replaceable air filter. g) In electrically-driven instruments the case of the instrument shall either be hermetically sealed or ventilated by large, vent holes provided with filters. Me
16、ans shall be provided to prevent misting of the inner surface of the cover glass. h) The rate adjustment shall not be operable from outside the case of the instrument. j) The instrument shall possess pointer freedom up to Rate4turns (nominally720 /min.) but, for instruments having a graduated “turn
17、scale” the scale is only required to extend to Rate2 on either side (nominally360 /min.). k) The damping of the “turn” mechanism shall be such that, when the gymbal is suddenly released from a Rate2 deflection on either side, the pointer shall reach zero or may pass not more than once beyond the zer
18、o mark, the amount of the overshoot being not greater than 1 / 16 in. The time of return from Rate2 to within 1 / 4in. of the zero mark shall not exceed2seconds. l) The “slip” mechanism shall consist of a damped pendulum or its equivalent. The indication shall be unaffected by increase in the magnit
19、ude of apparent gravity. Deviations of the direction of apparent gravity to the left shall cause the pointer (or its equivalent) to move to the left. 1) In course of preparation.BSG125:1950 2 BSI 02-2000 m) The damping of the “slip” mechanism shall be such that when the pendulum is suddenly released
20、 from a full-scale deflection on either side, the pointer (or its equivalent) shall reach zero or may pass not more than once beyond the zero mark, the amount of the overshoot being not greater than 1 / 16 in. The time of return to within 1 / 4in. of the zero mark shall not exceed one second. n) In
21、two-pointer instruments the “turn” pointer shall point vertically downwards in the zero turn position, and the “slip” pointer vertically upwards in the zero slip position. In instruments in which “slip” is indicated by a ball inclinometer, the “turn” pointer shall point vertically upwards in the zer
22、o turn position and the “slip” indication shall be beneath the “turn” indication. o) The instrument shall be so designed that shock loads giving an acceleration of50g in any direction, do not impair the performance. 5 Accuracy a) All instruments shall be tested for zero accuracy with the rotor runni
23、ng, and the tolerances given in Table 1 may be converted into a linear dimension based on the deflection law of the instrument. b) When an instrument is provided with a calibrated “turn” scale the deflected accuracy shall also be in accordance with graduations1 and2 of Table 1, when the instrument i
24、s banked at the angles stated. c) The sensitivity of the “slip” mechanism shall be such that a deviation of1 from correct bank shall be easily visible. 6 Marking The instrument shall be marked on the case with the speed range for which it is suitable. Table 1 Graduation Nominal rate of turn degrees/
25、min. Bank angle degrees. Tolerance for suction-driven instruments. Tolerance for electrically-driven instruments. Degrees of turn per minute. Degrees of turn per minute. 140knots 280knots At normal temp. At20 C. &50 C. At normal temp. At20 C. &+50 C. 0 1 2 0 180 360 21 38 38 57 10to+10 167 to193 319
26、 to401 20 to+20 146 to214 282 to451 5 to+5 171 to189 342 to378 10 to+10 169 to193 335 to358blankBS G125:1950 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 standards i
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