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Jim Floyd:RAeS Lecture

Jim Floyd:
RAeS Lecture pg 7

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This republication has been made possible thanks to the assistance of
The Royal Aeronautical Society and Dr. James C. Floyd. This is quite a lengthy lecture and was presented in December 1958. At that time the Arrow was in phase one flight tests.
We hope you enjoy this piece of aviation history.
Scott McArthur. Webmaster, Arrow Recovery Canada.


The Fourteenth British Commonwealth Lecture

The Canadian Approach to All-Weather
Interceptor Development

by

J. C. FLOYD, A.M.C.T., P.Eng., F.C.A.l., M.I.A.S., F.R.Ac.S.
(Vice-President, Engineering, Avro Aircraft Limited, Canada)

The Fourteenth British Commonwealth Lecture," The Canadian Approach to All-Weather Interceptor Development," by Mr.J. C. FLOYD, A.M.C.T., P.Eng., F.C.A.l., M.I.A.S., F.R.Ac.S. was given in the 9th October 1958 at the Royal Institution, Albemarle Street, London, W.1.
The Chair was taken by Dr. E. S. Moult, C.B.E., Ph.D., B.Sc., F.R.Ae.S., Vice-president of the Society, deputising for the President, Sir Arnold Hall, M.A., F.R.S., F.R.Ae.S., who was ill.
Dr. Moult first read a telegram from the President and then introduced the Lecturer, a distinguished Canadian engineer, for this Fourteenth Commonwealth Lecture. Mr. Floyd joined A. V. Roe and Co. Ltd., at Manchester, as an apprentice in 1929, progressing through the design and production offices to become Chief Projects Engineer in 1944. Immediately after the War he joined A. V. Roe Canada Ltd., at first as Chief Technical Officer, becoming Chief Design Engineer in 1949, Works Manager 1951, and Chief Engineer in 1952. He is now Vice-President, Engineering, Avro Aircraft Ltd. Mr. Floyd became a naturalized Canadian in 1950 and in the same year was the first non-American to receive the Wright Brothers Medal, which was awarded for his contributions to aeronautics, including his design of the Avro Jetliner. More recently, he had been known for his work on the Avro CF-100 interceptor and for the Avro Arrow, which made its first flight in March 1958.

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WEAPON PACK

  A number of different kinds of missile armament can be carried in the large armament bay. The missiles are housed in a removable pack below the fuselage, attached at four points, and re-arming is very fast, the pack being lifted into place by a mobile rig which also serves as a transport dolly (Fig. 12).


FIGURE 12. Weapon pack.

FREE FLIGHT MODELS

  During the early phases of preliminary design, we decided that a great deal of data could be accumulated from free flight model firing, especially on dynamic stability and control, and also that free flight models would give a better means of establishing the aircraft drag than wind tunnel models, since the effect of the data boom on the relatively low Reynolds numbers of the wind tunnel tests, and the difficulty of making an accurate strain gauge drag balance, free from the interaction of other components, made it difticult to establish the drag by tunnel tests.
  We estimated that 1/8th scale models, fired to the correct Mach number at low altitude would give approximately full scale Reynolds numbers, due to the higher air density closer to sea level.
  The first model was fired in December 1954 to evaluate the techniques for launch, separation, telemetering, and tracking (Fig. 13). Four crude models had been made with an approximate representation of the CF-105 configuration to check general problems associated with firing. These were followed by seven considerably more sophisticated and representative models, having up to 16 channels of telemetry. Of the last seven models, three were drag models, two lateral stability models, and two longitudinal stability models.
  The models were all launched from a zero length launcher, and boosted to a Mach number of 1.7 by a JATO booster, having 50,000 lb. of thrust for a period of three seconds.
  The telemetry package radioed back to a ground recording station, position, pressures, acceleration data and so on.
  Separation was achieved by means of drag; the greater drag to weight ratio of the boosters when power is exhausted, slows the booster more rapidly than model, and the two separate.


FIGURE 13. Free flight model launching

  Most of the firings were done at the Canadian Armament Research and Development Establishment at Picton, on the shores of Lake Ontario, which has a range telemetry ground station. Our own telemetry mobile trailer receiver was also used as a check.
   Additional range instrumentation consisted of kine-theodolites taking pictures at five frames a second, complete with azimuth and elevation scales. All the shutters of the cameras were synchronised. Doppler veloci-meter radar was utilised to obtain correct velocity information, with an 8 ft. diameter transmitting and receiving dish.
There was also a tracking radar, operating 600 pulses per second on "S" band.Quick-look data was obtained from a plotting board.
  Two models were fired at the N.A.C.A. Range Wallops Island. One of these models had the fuselage, contoured for what we called, " super" area ruling, to ascertain what decrease in supersonic drag might expected as we optimised the shape to achieve
minimum drag at a given speed. The gains were shown to be quite small.
  For the lateral stability models, lateral accelerations were excited by means of a yaw impulse system mounted in the nose of the model in the form of a motor-driven Geneva cross mechanism, containing five cartridges of 10 lb. second impulse, and firing alternately port and starboard, through a hole in each side of the nose at intervals of 1 1/2 seconds.
   On the longitudinal stability models, the elevators were actuated by a mechanism contained completely inside the model using a hydraulic oil-air accumulator.
  In all, these tests were remarkably successful, the three drag models provided the data to evaluate supersonic airframe drag and also served as a qualitative assessment of the CF-105 dynamic stability. We had no aborted firings, even on the crude models, and the reliability of the telemetry transmission was over 95 per cent. On one occasion, for instance, a model fired over Lake Ontario hit the water after the test and then skipped out again over the surface, and continued to send back information to a group of surprised technicians at " point zero"!

DATA ACQUISION AND HANDLING

  With an aircraft of the complexity of the Arrow, an extremely large number of individual readings of several hundred parameters are necessary during a test flight, if reliable dynamic characteristics of both aircraft and systems are to be obtained.
  With the possible data points per flight running into several million, it is obvious that manual handling of this data would be impractical. The only way that such a mass of data can be handled quickly is by means of an automatic system.
  This data handling system requires that the information be presented in an electrical form, and magnetic tape is used to store the large masses of information received.
  It was felt that " in flight " monitoring would be necessary during the Arrow flight testing to enable the maximum data to be obtained from each flight, and to monitor against possible troubles in flight. The means of accomplishing this was already present in the company in the form of a mobile telemetry unit which had been initially constructed for the free flight model firings.
  The Arrow data acquisition and handling system is composed of an airborne multi-channel recorder system, an airborne radio telemetry link, a mobile telemetry receiving station, and a mobile data reduction unit capable of reducing data obtained by either airborne system (Fig. 14).


FIGURE 14. Data acquisitison system.

  With the large armament bay required on the Arrow, in the form of a removable self-contained unit, it has been relatively easy to house all of our telemetry transmitting instrumentation and oscillographs, and so on, in the weapon pack (Fig. 15).
  For visual monitoring of flight conditions a special "operations" room was prepared, containing recording oscillographs giving instantaneous visual records of data in analogue form during actual flight. Personnel in this room are in radio contact with the pilot by means of the conventional radio links, so that instructions and comments may be exchanged at any time during the flight.

FIGURE 15. Instrument pack.

  On the first series of flights, we were plagued with a number of minor problems, mainly due to the literally thousands of wires and connections running to the instrument pack. A central " patch board " has since been included to allow any circuit changes to be made at one location.

CONVERTED TO HTML, AND HYPERLINKS ADDED, MARCH 28, 2001.
Scott McArthur.

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