1、BRITISH STANDARD AEROSPACE SERIES CONFIRMED MAY 1998 BSG 234:1984 Specification for Self-aligning air flow angle transmitters for use on aircraft UDC 629.7.054.062.4BSG234:1984 This British Standard, having been prepared under the directionof the Aerospace Standards Committee, was published under th
2、e authorityofthe Board of BSI and comes into effect on 29 June1984 BSI 04-2000 The following BSI references relate to the work on this standard: Committee reference ACE/30 Draft for comment 83/75382 DC ISBN 0 580 13898 4 Committees responsible for this British Standard The preparation of this Britis
3、h Standard was entrusted by the Aerospace Standards Committee (ACE/-) to Technical Committee ACE/30 upon which the following bodies were represented: Civil Aviation Authority (Airworthiness Division) GAMBICA (BEAMA Ltd.) Ministry of Defence Society of British Aerospace Companies Limited Amendments i
4、ssued since publication Amd. No. Date of issue CommentsBSG234:1984 BSI 04-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Construction 1 3 Performance 1 4 Environmental conditions 2 5 Tests 3 Table 1 Aerodynamic accuracy 2 Table 2 Dynamic response 2 Publication
5、s referred to Inside back coverBSG234:1984 ii BSI 04-2000 Foreword This British Standard has been prepared under the direction of the Aerospace Standards Committee. It specifies requirements for self-aligning air flow angle transmitters for use on aircraft. The transmitters, when fitted with the ele
6、ctrical devices specified, will transmit the signal representative of the local air flow angle to the corresponding receiver/indicator. The standard specifies the characteristics of the input/output functions and the environmental resistance required of the transmitter. These transmitters are used i
7、n pilot indication (with a suitable indicator), stall warning and air data computers. Mounting configurations are not defined. 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. Complian
8、ce with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had
9、 amendments incorporated. This will be indicated in the amendment table on the inside front cover.BSG234:1984 BSI 04-2000 1 1 Scope This British Standard specifies construction and performance requirements for self-aligning air flow angle transmitters suitable for use on aircraft of all types. NOTE
10、1The titles of the publications referred to in this standard are listed on the inside back cover. NOTE 2The latest revision of an aerospace standard is indicated by a prefix number. 2 Construction The transmitter shall be capable of providing an output signal proportional to local air flow angle ove
11、r the range and in conjunction with the environmental conditions specified herein. The total angular range of the transmitter shall be30 minimum. Where electrical heaters are incorporated, they shall comply with3.4.2. The output shall be referenced to an arbitrary, repeatable fixed datum on the body
12、 of the transmitter. NOTE 1This may be provided by means of reference dowel pins. NOTE 2The transmitter should be designed and constructed to ensure that no parts work loose in service and that it will withstand the shocks, vibrations and other environmental conditions inherent in shipment, storage,
13、 installation and service. Consideration should be given to the likely effects on the transmitter when the aircraft on which it is installed is washed down with a high-pressure hose. This may affect the design of stops, if fitted, the shaft seal and any vents. 3 Performance 3.1 Input 3.1.1 The sensi
14、ng device shall consist of an externally mounted device which will align itself with the local air flow. NOTEThe body of the transmitter may be housed within the aircraft. 3.1.2 The transmitter shall be capable of operation from low speed(60knots e.a.s.) to supersonic Mach numbers (M2.5). NOTEThe al
15、ignment accuracy could be degraded at low speed. 3.1.3 The dynamic response of the transmitter shall be such that if the sensing device is displaced, it will rapidly realign itself with the local air flow with minimum overshoot over the declared altitude and speed range of the transmitter (see3.3.3)
16、. 3.1.4 The sensing device shall be capable of correctly aligning itself with the local air flow in atmospheric conditions which could contain rain, supercooled water droplets or ice crystals, as listed in clause4. 3.1.5 The aerodynamic drag of the external parts of the transmitter shall be the mini
17、mum consistent with the performance requirements specified in clause3. 3.2 Output 3.2.1 General. The transmitter shall be capable of supplying multiple electrically-isolated outputs. Each individual output signal shall comply with the relevant requirements of this specification. 3.2.2 Type of device
18、. The output signals shall be derived from one or more of the following devices. 3.2.3 Type I: Potentiometers. For a potentiometer transmitter, the resistance change shall be507/degree, i.e.for a50 range device the potentiometer resistance shall be25007 plus the end resistance(s) necessary to preven
19、t potentiometer burn-out in the event of a wiper short circuit. The resolution available from the potentiometer shall be at least0.1 of sensing device rotation. The maximum voltage across the potentiometer and hence current through the track shall be specified in the individual equipment specificati
20、on. The minimum voltage shall be5V. The maximum current which can be drawn from the wiper of the potentiometer shall be stated in the individual equipment specification. NOTEThis may control the characteristics and calibration of the receiver/indicator. The electrical output shall be referenced as f
21、ollows: the electrical reference of the potentiometer shall be taken as that point when the open circuit output voltage is exactly half of the voltage applied to the potentiometer. This electrical datum shall be referenced to the fixed arbitrary datum on the body of the transmitter to within 0.1 3.2
22、.4 Type II: Synchro resolvers. For a synchro resolver transmitter, the change in the electrical angle shall be at least1 /degree of sensing device travel. The synchro resolver shall operate from a26V r.m.s.400Hz single phase supply. a) Type I: Potentiometers. b) Type II: Synchro resolvers. c) Type I
23、II: Linear voltage differential transformers (LVDT). d) Type IV: Digital encoders.BSG234:1984 2 BSI 04-2000 The maximum signals from both the sine and cosine coils shall be individually not less than10V r.m.s. when operating into a resistive load of50007. The electrical reference shall be defined as
24、 occurring when the cosine signal is a maximum. This electrical reference shall be referenced to the fixed arbitrary datum on the body of the transmitter to within 0.1 . When the sensing device is rotated in a clockwise direction relative to the body of the transmitter, the electrical output of both
25、 the sine and cosine signals shall be in phase with the reference voltage. 3.2.5 Type III: Linear voltage differential transformers. For a linear voltage differential transformer, the transformer output shall be at least 50mV/degree of sensing device travel when operating into a50007 resistive load.
26、 The transformer shall operate from a26V r.m.s.400Hz supply. The electrical reference shall be defined as the point when the voltages in each half of the transformer are exactly equal and shall be referenced to the fixed arbitrary datum on the body of the transmitter to within 0.1 3.2.6 Type IV: Dig
27、ital encoder. The characteristics of the output of a digital encoder shall be as specified in the individual equipment specification. 3.3 Accuracy 3.3.1 Static accuracy (calibration). With the transmitter set up with its electrical reference, as specified in3.2, the actual output shall track the nom
28、inal output to within 0.1 of travel over the total sensing device travel. 3.3.2 Aerodynamic accuracy. With the transmitter set up as for3.3.1 and mounted in a wind tunnel, the electrical output shall indicate the true local air flow angle to within the value given in Table 1 over the range of the tr
29、ansmitter. Table 1 Aerodynamic accuracy 3.3.3 Dynamic response. With the transmitter set up in a wind tunnel, the sensing device shall be displaced and allowed to freely regain its aligned position. The time constant of the response, expressed as the time taken to move through63% of the displacement
30、 towards the final steady-state position, shall not exceed the values given in Table 2. Table 2 Dynamic response The dynamic overshoot shall not exceed15% of the displacement and the transmitter shall settle to a steady-state value within1“ cycles. Any difference between the initial aligned value an
31、d the final steady-state value shall be within the aerodynamic accuracy tolerance specified in3.3.2 without the aid of any external vibration. 3.4 Electrical characteristics 3.4.1 Electrical power supplies. The characteristics of the electrical power supplies shall be as specified in BS3G100-3 and t
32、he characteristics of low voltage supplies shall be as specified in the individual equipment specification. 3.4.2 Insulation resistance. The electrical circuits of the output devices and the ice protection devices shall be isolated. The insulation resistance between the electrical circuit of the ice
33、 protection device and the body of the transmitter shall be greater than10M7 at500V d.c. The insulation resistance between the body of the transmitter and the output devices shall be greater than10M7 at500V d.c. Transmitters containing electrical components incapable of meeting this test voltage sha
34、ll be tested at30V d.c. 3.5 Environmental conditions. The air flow angle transmitter shall comply with the requirements of clause3 when exposed to the environmental conditions listed in clause4 to the degree of severity specified in the individual equipment specification. 4 Environmental conditions
35、4.1 Vibration. To be tested in accordance with BS3G100-2.3.1, Region A. The time duration in any vibration category shall be specified in the individual equipment specification. 4.2 Temperature-pressure. To be tested in accordance with BS3G100-2.3.2. The aircraft classification and the equipment gra
36、de shall be specified in the individual equipment specification. 4.3 Mould growth. To be tested in accordance with BS3G100-2.3.3. (This cross-refers to BS2011-2.1J). 4.4 Differential pressure. To be tested in accordance with BS3G100-2.3.4. The equipment grade and the aircraft classification shall be
37、 specified in the individual equipment specification. Airspeed (knots e.a.s.) 90 120 180 300 and above Accuracy (degrees) 0.50 0.25 0.20 0.10 Airspeed (knots e.a.s.) 90 120 180 and above Time constant (s) 0.18 0.10 0.05BSG234:1984 BSI 04-2000 3 4.5 Acceleration. To be tested in accordance with BS3G1
38、00-2.3.6, gradeC. The acceleration class shall be specified in the individual equipment specification. 4.6 Tropical exposure. To be tested in accordance with BS3G100-2.3.7. 4.7 Salt mist. To be tested in accordance with BS3G100-2.3.8, severity1. (This cross-refers to BS2011-2.1Ka.) 4.8 Ice formation
39、. To be tested in accordance with BS3G100-2.3.9. 4.9 Impact icing. To be tested in accordance with8.7 of BS2G135:1967. 4.10 Water-proofness. To be tested in accordance with BS3G100-2.3.11, gradeA. 4.11 Fluid contamination. To be tested in accordance with BS3G100-2.3.12, class A. 4.12 Sand and dust 4
40、.12.1 Agent. Sand and dust in a suitable test chamber vented to the atmosphere shall be raised and maintained at a concentration of3.5g/m 3to8.8g/m 3and shall comply with the following. a) 100% shall pass through a100-mesh screen, i.e.diameter0.15mm. b) 982% shall pass through a140-mesh screen, i.e.
41、diameter0.10mm. c) 90 2% shall pass through a200-mesh screen, i.e.diameter0.075mm. d) 75 2% shall pass through a325-mesh screen, i.e.diameter0.045mm. e) The chemical composition shall be97% to99% SiO 2 . 4.12.2 Exposure of the transmitter. Subject the transmitter to the sand and dust jet along its s
42、ix major orthogonal axes in succession. Maintain the jet velocity between0.5m/s and2.5m/s. 4.12.3 First cycle. With the internal temperature of the test chamber maintained at+25 C and the relative humidity at not more than30%, subject the transmitter to an exposure of1h along each of its six major o
43、rthogonal axes in succession. 4.12.4 Second cycle. With the internal temperature of the test chamber raised and stabilized at+55 C and the relative humidity at not more than30%, subject the transmitter to an exposure of1h along each of its six major orthogonal axes in succession. At the end of this
44、exposure period, remove the transmitter from the chamber and cool to room temperature. Remove accumulated dust by brushing, wiping or shaking, taking care to avoid introducing additional dust into the equipment. Under no circumstances shall dust be removed by either air blast or vacuum cleaning. 4.1
45、2.5 Acceptance standard. In providing the aerodynamic accuracy of3.3.2, a maximum static frictional torque will have been established for routine production purposes. Following the sand and dust test, it shall be established that this value is not exceeded anywhere within the range of travel of the
46、sensing device in either direction of rotation. 4.13 Magnetic influence. To be tested in accordance with BS3G100-2.2. Determinations shall be made with both the signalling circuits and de-icing circuits energized and de-energized. 4.14 Radio interference. To be tested in accordance with BS3G100-4.2.
47、 5 Tests 5.1 Type tests. Type tests shall be carried out to demonstrate compliance with the requirements of3.5. 5.2 Routine production tests. Each transmitter shall comply with the requirements of3.3.1, 3.3.2 (at one speed),3.3.3 (at one speed) and3.4.2. 5.3 Production quality tests. Sample transmit
48、ters, selected as specified in the individual equipment specification, shall comply with the requirements of3.5, when tested as described in4.1, but limited to the resonance search only (see4.3 of BS3G100-2.3.1:1969), and when tested as described in4.2; and of5.2.4 blankBSG234:1984 BSI 04-2000 Publi
49、cations referred to BS2011, Basic environmental testing procedures. BS2011-2.1J, Test J Mould growth. BS2011-2.1Ka, Test Ka Salt mist. BS3G100, Specification for general requirements for equipment for use in aircraft. BS3G100-2, All equipment. BS3G100-2.3, Environmental conditions. BS3G100-2.3.1, Vibration. BS3G100-2.3.2, Temperature-pressure requirements. BS3G100-2.3.3, Mould growth. BS3G100-2.3.4, Differential pressure requirements. BS3G100-2.3.6, Acceleration requirements. BS3G100-2.3.7, Tropical exposure. BS3G100-2.3.8, Salt mist. BS3G100-2.3
