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Aileron Position Indicator

Technical Information

Catalogue No: C0603
Category: Flight Control
Object Type: Indicator/Instrument
Object Name: Aileron Position Indicator
Part No: SF66HSD/BU
Serial No: T8212
Manufacturer: Smiths Desynn
Division: Unknown
Platform(s): Harrier
Year of Manufacture: circa 1959
Dimensions: Width (mm): 30
Height (mm): 30
Depth (mm): 75
Weight (g): 110
Location: Triple Shelf Unit, RH (indicators) [Main Store]

Smiths Desynn (REGD) Indicator
Ser. No. T8212
French Pat. No. 925508
Volts 24
Mod 01 ... 05
Made in Gt. Britain


A good document on the operation of these remote indicating devices is ‘Review of Remote Indicating Systems for Instruments’ by F. Postlethwaite PH.D., M.Eng. This document was written in 1945 for the UK Ministry of Supply. These devices were widely used in aircraft, and are almost universal in their application, provided that the aircraft is fitted with a d.c. electric supply. In the U.S.A. the system is designated as a " d.c. Selsyn " whilst in this country the" Desynn ", system was developed. The Desynn system was modified and improved to make it suitable for continuous rotation of both the transmitter and the receiver. Such alteration also means that five wires have to be led to the transmitter of which three interconnect with the receiver. The angular position of the input brushes distributes the current in the three receiver coils so that a resultant magnetic flux is produced diametrically across the receiver, which, apart from a small inherent error, has the same angular position as the brushes. A polarized permanent magnet rotor which aligns itself with the resultant flux is employed and this prevents the possible occurrence of an angular ambiguity of 180 deg. The Desynn transmitter is a potentiometer wound in the form of a circle. The receiver is extremely compact and in this case is used to indicate the position of the Ailerons.

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