GB2039676A - Flow direction indicators - Google Patents

Flow direction indicators Download PDF

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Publication number
GB2039676A
GB2039676A GB7901782A GB7901782A GB2039676A GB 2039676 A GB2039676 A GB 2039676A GB 7901782 A GB7901782 A GB 7901782A GB 7901782 A GB7901782 A GB 7901782A GB 2039676 A GB2039676 A GB 2039676A
Authority
GB
United Kingdom
Prior art keywords
probe member
housing
detector
probe
aperture
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB7901782A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ferranti International PLC
Original Assignee
Ferranti PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ferranti PLC filed Critical Ferranti PLC
Priority to GB7901782A priority Critical patent/GB2039676A/en
Priority to DE19803001161 priority patent/DE3001161A1/en
Priority to FR8000907A priority patent/FR2447034A1/en
Publication of GB2039676A publication Critical patent/GB2039676A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/0006—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances
    • G01P13/004—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using the rotation of vanes
    • G01P13/0046—Indicating or recording presence, absence, or direction, of movement of fluids or of granulous or powder-like substances by using the rotation of vanes with electrical coupling to the indicating device
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/02—Indicating direction only, e.g. by weather vane
    • G01P13/025—Indicating direction only, e.g. by weather vane indicating air data, i.e. flight variables of an aircraft, e.g. angle of attack, side slip, shear, yaw
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/02—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer
    • G01P5/06—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer using rotation of vanes
    • G01P5/07—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer using rotation of vanes with electrical coupling to the indicating device

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Measuring Fluid Pressure (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
  • Indicating Or Recording The Presence, Absence, Or Direction Of Movement (AREA)

Abstract

An airstream direction detector comprises a cylindrical probe member 10 carrying flaps 13 and rotatably mounted in a housing. The probe member contains two passages whereby pressure is applied to the flaps causing the probe to rotate until pressures balance. Each passage extends between an aperture 16 located towards the free end of the probe member and an opening 23 within the housing. Each passage is formed in three parts, a first one of which, 24, extends between the aperture 16 and a drain hole 22 located nearer to the housing. A second part 27 of the passage extends from the aperture towards the free end of the probe member and communicates with the third part 25 which extends along the probe member 10 to the opening 23. The passages are formed by cut outs in a rod 21 extending through a tubular member containing the apertures and holes. <IMAGE>

Description

SPECIFICATION Airstream direction detector This invention relates to airstream direction detectors, and in particularto probe members for such detectors.
Airstream direction detectors are carried on aircraft to provide an indication of the direction, relative to the airframe, of the local airflow. Several different types of detector are known, but one of the most common is the pneumatic balance type. In this, one or two paddles are supported for rotation in separate chambers, and air is admitted along a rotatable probe to which the paddles are secured. Two sets of openings in the probe, usually 90 apart, are connected to the chamber or chambers such that one side of the or each paddle is subject to the air pressure from one set of openings whilst the other side of the or each paddle is subject to the air pressure from the other set of openings. If the two air pressures are unequal the paddle, and hence the probe, will rotate until there is a pressure balance across the paddle.When this is achieved the airflow is along the bisector of the angle between the two sets of openings. The angular position ofthe probe may be indicated electrically.
One of the problems arising with the use of pneumatic balance detectors is that water is able to enter the sets of openings. The presence of water in the paddle chambers would prevent the correct operation of the detector, and must therefore be avoided. The probe of such a detector is therefore fitted with an electric heater for the purpose of evaporating away any water which enters the openings. These openings are small, and access for water is not easy, but nevertheless some water can enter when the heaters are switched off. This will normally occur only when the aircraft is on the ground, and it is known to fit covers over the probes. However, the accidental leaving in place of such a cover could have serious consequences.It is known to provide suitable drain holes in the probe to allow water to drain away, though this usually requires some form of enlargement of the passage go allow water to reach the drain holes. For example, it is known to use a conical probe, with the larger diameter adjacent to the skin of the aircraft. This allows for the provision of sumps into which the water may drain, but a conical probe has certain disadvantages such as higher aerodynamic drag than a cylindrical probe. In a cylindrical probe, however, it is difficult to provide such a sump, and care must be taken to prevent the drain holes from acting as air pressure bleed holes and affecting the operation of the instrument.
It is an object of the invention to provide an airstream direction detector having a cylindrical probe provided with means for draining away any water which enters the probe.
According to the present invention there is provided an airstream direction detector which includes a cylindrical probe member extending from a housing and supported in the housing for rotation about the longitudinal axis of the probe member, the probe mmhnr onntnininn t'A,fl nnssnnAn nSCRSnoR extending between at least one apertures located towards the free end of the probe member and an opening positioned within the housing, each passage comprising a first part extending between the aperture and a drain hole located nearer to the housing than is the aperture, a second part extending from the aperture towards the free end of the probe member, and a third part extending from the opening and communicating with the second part.
The invention will now be described with reference to the accompanying drawings, in which Figure 1 is a part-sectioned isometric view of a detector; Figure 2 is a similar view of the probe member of Figure 1; Figure 3 is an isometric view of part of the probe member of Figures 1 and 2; Figure 4 is a part-sectioned side view of the probe member; Figure 5 a sectional view of the probe member along the lineV-Vof Figure 4; and Figures 6 and 7 are side views of part of the probe member, looking in different directions.
Referring now to Figure 1, a typical airstream direction detector comprises a cylindrical probe member 10 extending from a housing 11, and supported in the housing so as to be capable of rotation about the longitudinal axis of the probe. The housing 11 has an outer flange 12 arranged to fit against an aperture in the skin of an aircraft, in such a position that the probe member 10 is substantially normal to the direction of local airflow. The end of the probe member 10 inside the housing 11 carries two diametrically-opposed flat extensions or paddles 13, and the interior of the housing is divided up by wedge-shaped partitions 14 into two separate chambers 15.
Two passages are formed within the probe member 10, each terminating towards the free end of the probe member in a row of apertures 16. The two rows of apertures emerge in positions 90" apart. The other end of each passage communicates with both chambers 15, on one side of one paddle and on the opposite side of the other paddle.
The inner end of the probe member 10 carries the moving contact 17 at least one potentiometer having a track 18.
In operation, the two rows of apertures 16 face in a forwards direction when the aircraft is in motion, and the build-up of air pressure in the passages results in a pressure being applied to each side of each of the two paddles 13. If the direction of the airflow is along the bisector of the angle between the two rows of apertures 16, then the pressure on each side of each paddle will be the same. If the airflow is along any other direction then the pressures on each side of each paddle will be different, and this will result in the rotation of the probe member until balance is achieved. The extent of any rotation is indicated by the or each potentiometer.
If the construction of the probe member was as simple as is suggested above, then the problems caused by the presence of water in the air passages would occur. Figures 2 and 3 illustrate the actual orobe construction according to the invention. As shown in Figure 2, the probe member 10 is made up from a tube 20 into which is secured, say by brazing, a rod 21 into which the various passages are machined The outer tube 20 has formed in it the two rows of apertures 16, only one being visible in Figure 2. Also, for each of the two passages, there is a drain hole 22 and the hole 23 which communicates with the chambers 15 inside the housing. Channel 24 is narrower than channel 25, and drain hole 22 correspondingly smaller than hole 23 to prevent the loss of air pressure in the passages leading to the chambers 15.
Figure 3 shows the rod 21, machined to form one of the two passages, the other being on the underside of the rod 21. As will be seen in both Figure 2 and Figure 3, the rod 21 is machined along both edges to provide two channels 24 and 25, separated by a dividing wall 26. The dividing wall stops short of the end of the rod 21 so that the two channels 24 and 25 are joined by a bridging channel 27. The end of the rod is not machined away so that it forms an end plug 28 when positioned in the tube 20. It will be seen from Figure 2 that the dividing wall 26 extends just beyond the apertures 16 in the tube. The channel 24 is narrower than channel 25 and extends from the bridging channel 28 to a position opposite the drain hole 22 in the tube 20. This channel thus forms the first part of the passage visible in Figures 2 and 3.
Channel 25, forming the second part of the passage, extends from the bridging channel 27 to a position opposite the hole 23 in the tube 20.
It will be seen that, depending upon the attitude of the probe member, any water entering the apertures i6 will either pass out through the drain hole 22 or collect in the bridging channel 27. In either case it is prevented from passing along the channel 25 and into the housing.
The remaining Figures show the construction of one form of probe member. Figures 4 and 5 show the comolete probe member, whilst Figures 6 and 7 illustrate features of the rod 21.
As shown in Figure 4, the tube 20 is longer than the rod 21, extending beyond the end 28 of the rod.
In addition, an enlargement 29 is formed on the tube 21 to locate a bearing about which the probe member is abie to rotate. Figure 4 shows the drain holes 22 for both passages, and the edges of both the holes 22 for both passages, and the edges of both the holes 23 which communicate with the chambers in the housing. The outer end oi tube 20 is closed by a plug 30, and the space between plugs 28 and 30 is occupied by a thermostat 31 intended to maintain the temperature of the probe member at a required value when in use. As will be seen from the cross-sectional view of Figure 5, the rod 21 is formed with two grooves 32 and 33 in addition to the channels already mentioned. Groove 32 contains the electric wires leading to the thermostat 31, whilst groove 33 accommodates an electric heater (not shown). In operation the thermostat and heater maintain the probe member at such a temperature that any water in the bridging channel 27 or in channel 24 is evaporated away.

Claims (7)

1. An airstream direction detector which includes a cylindrical probe member extending from a housing and supported in the housing for rotation about the longitudinal axis of the probe member, the probe member containing two separate passages each extending between at least one aperture located towards the free end of the probe member and an opening positioned within the housing, each passage comprising a first part extending between the aperture and a drain hole located nearer to the housing than is the aperture, a second part extend- ing from the aperture towards the free end of the probe member, and a third part extending from the opening and communicating with the second part.
2. A detector as claimed in Claim 1 in which the first part of each passage and the drain hole present a higher aerodynamic impedance than do the second and third parts of the passage.
3. A detector as claimed in either of Claims 1 or 2 in which the second and third parts of each passage meet in an enlarged area forming a water trap.
4. A detector as claimed in any one of Claims 1 to 3 in which the probe member is constructed from a tube in which are formed the apertures the drain holes and the said openings, and a rod-shaped member fitted into the tube and having the passages formed on its surface.
5. A detector as claimed in any one of Claims 1 to 4 which includes a heater and a thermostat together arranged, in operation, to prevent the collection of water in the passages.
6. A detector as claimed in any one of the preceding claims in which the apertures communicating with the two passages are located 90 apart around the periphery of the probe member.
7. An airstream direction detector substantially as herein described with reference to the accompanying drawings.
GB7901782A 1979-01-17 1979-01-17 Flow direction indicators Withdrawn GB2039676A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB7901782A GB2039676A (en) 1979-01-17 1979-01-17 Flow direction indicators
DE19803001161 DE3001161A1 (en) 1979-01-17 1980-01-15 DETECTOR FOR DIRECTION OF AIRFLOWS
FR8000907A FR2447034A1 (en) 1979-01-17 1980-01-16 AIR CURRENT DIRECTION DETECTOR

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7901782A GB2039676A (en) 1979-01-17 1979-01-17 Flow direction indicators

Publications (1)

Publication Number Publication Date
GB2039676A true GB2039676A (en) 1980-08-13

Family

ID=10502584

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7901782A Withdrawn GB2039676A (en) 1979-01-17 1979-01-17 Flow direction indicators

Country Status (3)

Country Link
DE (1) DE3001161A1 (en)
FR (1) FR2447034A1 (en)
GB (1) GB2039676A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1092126A1 (en) * 1998-07-02 2001-04-18 Avionics Specialties, Inc. Improvements to multifunction aircraft probes
US20120118037A1 (en) * 2010-05-07 2012-05-17 Thales Device for Checking a Flow Pressure Measurement Probe, and Probe Comprising the Device
EP3444617A1 (en) * 2017-08-17 2019-02-20 Rosemount Aerospace Inc. Water management system for angle of attack sensors
US10730637B2 (en) 2017-09-29 2020-08-04 Rosemount Aerospace Inc. Integral vane base angle of attack sensor
US11162970B2 (en) 2019-06-17 2021-11-02 Rosemount Aerospace Inc. Angle of attack sensor
US11181545B2 (en) 2017-08-17 2021-11-23 Rosemount Aerospace Inc. Angle of attack sensor with thermal enhancement
US11649057B2 (en) 2019-12-13 2023-05-16 Rosemount Aerospace Inc. Static plate heating arrangement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19721938A1 (en) * 1997-05-26 1998-12-03 Peter Dr Ing Ambros Vector measuring method e.g. for air or water flow, or for radioactivity, light and sound

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB881902A (en) * 1957-02-25 1961-11-08 Automation Inc Of Virginia Improved probe assembly
US2971375A (en) * 1959-09-21 1961-02-14 Specialties Inc Airstream direction detector probe
FR2105080B1 (en) * 1970-09-23 1974-02-01 Thomson Csf

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1092126A1 (en) * 1998-07-02 2001-04-18 Avionics Specialties, Inc. Improvements to multifunction aircraft probes
EP1092126A4 (en) * 1998-07-02 2002-11-27 Avionics Specialties Inc Improvements to multifunction aircraft probes
EP1666844A2 (en) * 1998-07-02 2006-06-07 Avionics Specialties, Inc. Improvements to multifunction aircraft probes
EP1666844A3 (en) * 1998-07-02 2006-06-21 Avionics Specialties, Inc. Improvements to multifunction aircraft probes
US20120118037A1 (en) * 2010-05-07 2012-05-17 Thales Device for Checking a Flow Pressure Measurement Probe, and Probe Comprising the Device
US9021856B2 (en) * 2010-05-07 2015-05-05 Thales Device for checking a flow pressure measurement probe, and probe comprising the device
EP3444617A1 (en) * 2017-08-17 2019-02-20 Rosemount Aerospace Inc. Water management system for angle of attack sensors
US10393766B2 (en) 2017-08-17 2019-08-27 Rosemount Aerospace Inc. Water management system for angle of attack sensors
US11181545B2 (en) 2017-08-17 2021-11-23 Rosemount Aerospace Inc. Angle of attack sensor with thermal enhancement
US11768219B2 (en) 2017-08-17 2023-09-26 Rosemount Aerospace Inc. Angle of attack sensor with thermal enhancement
US10730637B2 (en) 2017-09-29 2020-08-04 Rosemount Aerospace Inc. Integral vane base angle of attack sensor
US11162970B2 (en) 2019-06-17 2021-11-02 Rosemount Aerospace Inc. Angle of attack sensor
US11649057B2 (en) 2019-12-13 2023-05-16 Rosemount Aerospace Inc. Static plate heating arrangement

Also Published As

Publication number Publication date
FR2447034A1 (en) 1980-08-14
DE3001161A1 (en) 1980-07-24

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Legal Events

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)