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A New Turn Indicator

A New Turn Indicator 146 AIRCRAFT ENGINEERING June, 1931 A Gyroscopic Instrument with an Ingenious Mounting and Fluid-Friction Drive of General Application NE W aircraft instrument has been produced utilised in the new mounting by constructing the Th e recovery, or re-erection, from any displace­ b y Mr. Pollock Brown which, it is claimed, roto r with fan shaped blades which constitute an men t can be accelerated, so as to give almost combines the functions of turn indicator unbiased drag on the speed, and, therefore, a instantaneou s rectification, by temporarily tighten­ and fore-and-aft level. The details of the "P.B . definite slip in the fluid drive of the bearing : thus ing up the bearing drive. For this purpose a small Deviator, " as the device is called, can bo seen in when the spindle axis is deflected the rotor axis is pea ball is let into a recess on the axis of the driving th e accompanying drawing. no t immediately coerced to follow. . ball and can be pressed against the bearing surface The principle of the gyrostat has always formed Th e performance depends on the rotor energy (a b y the axial thrust of a small rod passing through an irresistible attraction to inventors and others function of its moment of inertia and its angular th e spindle, which is hollow. The push button when developing apparatu s for direction indicating, velocity), the fit of the universal bearing in relation seen a t the bottom of the figure operates this. This device may be very useful when changing direction bu t the ideal of a frictionlcss universal mounting to the lubricant used, ard the speed of the slip in, say, a vertical sense. is extremely difficult to attain. It has, however, combined with proper proportions in design. It led to many ingenious devices to counter the pro­ Th e particular type of instrument illustrated is cessional troubles which arise from the frictional arrange d for a drive from the engine speed-indicator torques, all leading to complex constructions and flexible shaft without interfering with that instru­ sacrifice of reliability, in accuracy if not in ment . The diameter of the deviator flange is 4 in. functioning. and the weight about 25 oz. Thre e Degrees of Freedom Teste d in Flight When a directional indicator is required only as a I n actual flight the deviator appears to carry out supplement to the magnetic compass, the exacting its designed functions satisfactorily, subject to the demand s of the above ideal can be considerably tw o reservations indicated later. modified as deflections on a reasonable time base I t was tested in a Desoutter cabin monoplane, become acceptable. A universal coupling drive to an d although it was impossible to find any clouds, a th e gyroscopic rotor at once suggests itself but ver y fair indication of its performance could be unfortunately the follow-up of the rotor axis to arrived at by throwing the machine about, and then an y deflection is spiral in form, as well as being levelling up again by means of the instrument, rapid, and so is useless. All development has, withou t looking at the ground. will thus be realised that the rate of follow-up of therefore, been aroun d a gyroscope wit h " tw o degrees I t appears that care must be exercised under th e rotor axis depends on the amount of deflection of freedom," which can only show th e rate of deflec­ two conditions. which governs the torque, and this can be so small tion in one plane by the precession at right angles Firstly, should the machine be sideslipping with a s to allow the actual amount of a reasonable t o that plane, against springs to control the sensi­ one wing down, but otherwise maintaining level deflection to be observed. tivity and dash pots to eliminate oscillations. flight, the deviator will read exactly the same as Th e new form of mounting with "thre e degrees Th e Instrument Described for a good turn ; that is i t will move along one of the of freedom" adopted in the P.B. Deviator con­ Th e P.B. Deviator for use in blind flying is one horizontal bars. There is no great likelihood of stitute s its own drive to the rotor with great particula r development of the new mounting, the thi s trouble being met with, as it requires some care simplicity and is applicable to man y other purposes. features of which should be clear from the fore­ to sideslip without the nose going up or down— I t also provides an exceptionally slow and radial which will be instantly shown by rise or fall of going and reference to the accompanying drawing. follow-up, or erection, from deflection in any th e indicator Th e rotor axis is extended to carry a small disc direction. Secondly, should the indicator be found to be in faced with a yellow resin on its extremity. This The rotor, as can be seen from the illustration, is one of the sectors, i t is advisable to correct in two disc is immediately behind cross wires, fixed and the mounted on a single cup and ball-bearing on the movements . For example, should the indicator casing, which was slightly convexed so tha t the disc end of a spindle and is driven by the fluid friction be in the top right-hand corner, it should first of all remains the same distance from them at all angles. of tha t bearing. If balanced it will, therefore, align be brought back to th e vertical line by means of the An y deviation of the aircraft, represented by the its axis with tha t of th e driving spindle. aileron and rudder controls, and then brought down casing and cross wires is at once indicated by the I t is well known that the frictional resistance to the centre by means of the elevators. Other­ disc, which temporarily retains the previous line between two surfaces in one direction is almost wise it has a tendency to " hunt, " and confusion of flight, being of a diameter calculated to represent eliminated if a definite slip is caused in another ma y arise as to precisely what is happening to the 10 degrees deflection. direction, say, at right angles. This has been machine . If used in conjunction with a cross-level and compass the instrument seems capable of doing all tha t is claimed for it. Historica l Congress Th e second International Congress of the History of Science and Technology is being hold in London from June 29 to July 3, 1931. The Honorary Secretar y is Mr. II. W. Dickinson, and the official address. The Science Museum, South Kensington, London , S.W.7. Th e Congress originated with the Comite Inter- . national d'Histoire des Sciences founded at Oslo on Augus t 17, 1928. This body meets annually and organises a congress every three years, of which thi s is th e second. It is held with the co-operation of the Comite International des Sciences Historiques an d the two other Societies, the History of Science Society of America and the British New- comen Society for the Study of the History of Science and Technology. The inaugural meeting will be held at 3 p.m., on Monday, June 29, and durin g the morning sessions papers will be read . in the following groups: (1) The Sciences as an integra l part of general historical study; (2) Historical and contemporary inter-relationships of the physical and biological sciences; (3) Inter-dependenc e of pure and applied science. Subscription rates to the Congress are: for member s of an y of th e four bodies mentioned above, £1 ; others, £1 5s. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

A New Turn Indicator

Aircraft Engineering and Aerospace Technology , Volume 3 (6): 1 – Jun 1, 1931

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb029411
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Abstract

146 AIRCRAFT ENGINEERING June, 1931 A Gyroscopic Instrument with an Ingenious Mounting and Fluid-Friction Drive of General Application NE W aircraft instrument has been produced utilised in the new mounting by constructing the Th e recovery, or re-erection, from any displace­ b y Mr. Pollock Brown which, it is claimed, roto r with fan shaped blades which constitute an men t can be accelerated, so as to give almost combines the functions of turn indicator unbiased drag on the speed, and, therefore, a instantaneou s rectification, by temporarily tighten­ and fore-and-aft level. The details of the "P.B . definite slip in the fluid drive of the bearing : thus ing up the bearing drive. For this purpose a small Deviator, " as the device is called, can bo seen in when the spindle axis is deflected the rotor axis is pea ball is let into a recess on the axis of the driving th e accompanying drawing. no t immediately coerced to follow. . ball and can be pressed against the bearing surface The principle of the gyrostat has always formed Th e performance depends on the rotor energy (a b y the axial thrust of a small rod passing through an irresistible attraction to inventors and others function of its moment of inertia and its angular th e spindle, which is hollow. The push button when developing apparatu s for direction indicating, velocity), the fit of the universal bearing in relation seen a t the bottom of the figure operates this. This device may be very useful when changing direction bu t the ideal of a frictionlcss universal mounting to the lubricant used, ard the speed of the slip in, say, a vertical sense. is extremely difficult to attain. It has, however, combined with proper proportions in design. It led to many ingenious devices to counter the pro­ Th e particular type of instrument illustrated is cessional troubles which arise from the frictional arrange d for a drive from the engine speed-indicator torques, all leading to complex constructions and flexible shaft without interfering with that instru­ sacrifice of reliability, in accuracy if not in ment . The diameter of the deviator flange is 4 in. functioning. and the weight about 25 oz. Thre e Degrees of Freedom Teste d in Flight When a directional indicator is required only as a I n actual flight the deviator appears to carry out supplement to the magnetic compass, the exacting its designed functions satisfactorily, subject to the demand s of the above ideal can be considerably tw o reservations indicated later. modified as deflections on a reasonable time base I t was tested in a Desoutter cabin monoplane, become acceptable. A universal coupling drive to an d although it was impossible to find any clouds, a th e gyroscopic rotor at once suggests itself but ver y fair indication of its performance could be unfortunately the follow-up of the rotor axis to arrived at by throwing the machine about, and then an y deflection is spiral in form, as well as being levelling up again by means of the instrument, rapid, and so is useless. All development has, withou t looking at the ground. will thus be realised that the rate of follow-up of therefore, been aroun d a gyroscope wit h " tw o degrees I t appears that care must be exercised under th e rotor axis depends on the amount of deflection of freedom," which can only show th e rate of deflec­ two conditions. which governs the torque, and this can be so small tion in one plane by the precession at right angles Firstly, should the machine be sideslipping with a s to allow the actual amount of a reasonable t o that plane, against springs to control the sensi­ one wing down, but otherwise maintaining level deflection to be observed. tivity and dash pots to eliminate oscillations. flight, the deviator will read exactly the same as Th e new form of mounting with "thre e degrees Th e Instrument Described for a good turn ; that is i t will move along one of the of freedom" adopted in the P.B. Deviator con­ Th e P.B. Deviator for use in blind flying is one horizontal bars. There is no great likelihood of stitute s its own drive to the rotor with great particula r development of the new mounting, the thi s trouble being met with, as it requires some care simplicity and is applicable to man y other purposes. features of which should be clear from the fore­ to sideslip without the nose going up or down— I t also provides an exceptionally slow and radial which will be instantly shown by rise or fall of going and reference to the accompanying drawing. follow-up, or erection, from deflection in any th e indicator Th e rotor axis is extended to carry a small disc direction. Secondly, should the indicator be found to be in faced with a yellow resin on its extremity. This The rotor, as can be seen from the illustration, is one of the sectors, i t is advisable to correct in two disc is immediately behind cross wires, fixed and the mounted on a single cup and ball-bearing on the movements . For example, should the indicator casing, which was slightly convexed so tha t the disc end of a spindle and is driven by the fluid friction be in the top right-hand corner, it should first of all remains the same distance from them at all angles. of tha t bearing. If balanced it will, therefore, align be brought back to th e vertical line by means of the An y deviation of the aircraft, represented by the its axis with tha t of th e driving spindle. aileron and rudder controls, and then brought down casing and cross wires is at once indicated by the I t is well known that the frictional resistance to the centre by means of the elevators. Other­ disc, which temporarily retains the previous line between two surfaces in one direction is almost wise it has a tendency to " hunt, " and confusion of flight, being of a diameter calculated to represent eliminated if a definite slip is caused in another ma y arise as to precisely what is happening to the 10 degrees deflection. direction, say, at right angles. This has been machine . If used in conjunction with a cross-level and compass the instrument seems capable of doing all tha t is claimed for it. Historica l Congress Th e second International Congress of the History of Science and Technology is being hold in London from June 29 to July 3, 1931. The Honorary Secretar y is Mr. II. W. Dickinson, and the official address. The Science Museum, South Kensington, London , S.W.7. Th e Congress originated with the Comite Inter- . national d'Histoire des Sciences founded at Oslo on Augus t 17, 1928. This body meets annually and organises a congress every three years, of which thi s is th e second. It is held with the co-operation of the Comite International des Sciences Historiques an d the two other Societies, the History of Science Society of America and the British New- comen Society for the Study of the History of Science and Technology. The inaugural meeting will be held at 3 p.m., on Monday, June 29, and durin g the morning sessions papers will be read . in the following groups: (1) The Sciences as an integra l part of general historical study; (2) Historical and contemporary inter-relationships of the physical and biological sciences; (3) Inter-dependenc e of pure and applied science. Subscription rates to the Congress are: for member s of an y of th e four bodies mentioned above, £1 ; others, £1 5s.

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Jun 1, 1931

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