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Jim Floyd:RAeS Lecture

Jim Floyd:
RAeS Lecture pg 8

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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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GROUND TEST PROGRAMME

  The philosophy of proceeding immediately with, production type build which we adopted on the CF-105, and which I will discuss later, obviously involves greater technical risks than the prototype/pre-production/production technique and, to protect as much of our engineering investment as possible, the decision was made early in the programme to carry out what was considered at the time to be an extraordinary amount of structural and systems testing.
  A large proportion of this testing was used for development purposes, for instance, the basic development of the control system and damping system was done on the control system rig.
  Many of the major structural tests, however, could not be considered in the development category, since production components were required from Manufacturing, and these components were not, in many cases, ready until the first aircraft was about to fly. In these cases, the test became more of a check on the completed design.
  A large number of critical components were checked prior to flight. This included the checking of fatigue of typical joints and structures, elevated temperature testing, panel and torsion box testing, and so on.

FIGURE 16. Structural static test rig.

  The next step in the structural programme was to test the complete aircraft in the large static test rig (Fig. 16). These tests began in early 1958, the objective being to confirm the calculated internal load distribution in the complete aircraft structure from the applied ,external loads, and to confirm the calculated stiffness and deflections of the structure under load, in addition to establishing the overall structural strength of the airframe under limit load conditions for various flight and landing cases.
  In the major cases, up to 30 hydraulic systems are used to apply the loads, via a multiple beam system, to some 1,100 points on the aircraft. This has led to the use of an automatic load control system which allows control to be maintained by a single operator through regulating valves.
  The load in each hydraulic jack is sensed by a strain gauge system to ensure that the overall load is compatible with the percentage of limit load to be applied. More than 3,000 strain gauge recording stations are used on the structure, and 300 deflection gauge stations. The central strain gauge recording unit is capable of reading out close to 800 stations in 25 minutes. The results are simultaneously typewritten and punched on to IBM cards for ease of processing by the Technical Office.

TRANSIENT HEATING TESTS

  Transient heating tests were made on representative sections of the fuselage and wing using radiant heat lamps powered by a variable voltage supply controlled by a simple analogue computer.


FIGURE 20. Static testing of crew escape systern.

SYSTEMS TESTING

Flying Control System Rig
  Since this rig was used for basic development of the flying control system, it was a fairly sophisticated rig, containing a dummy cockpit, a complete control system, closely controlled electric motor drives to simulate various engine conditions, all control surfaces and adjacent structure, and the synthetic stability system. (Fig. 17).
  For the aerodynamic response tests, surface loading was provided by large leaf springs attached to the surfaces, and the tests simulated correct inertial conditions at the same time maintaining structural stiffness.
  A large amount of instrumentation was provided to record motions of the actuators, valves, servos, and so on, together with hydraulic system pressure at critical points in the system. On this rig we were able to make complete evaluation of the flying control system from the cockpit to the control surfaces. The rig was also used during simulation tests on the complete aircraft.   This particular rig is tied in with a co-axial cable to the Analogue Computer Room, some distance away. Output from potentiometers mounted at the control surfaces were transmitted to the computers, which in turn fed in derivatives obtained from wind tunnel testing. Landing, take-off and manoeuvring under gust conditions were simulated to give the pilot some feel of aircraft problems, including break-out forces.
  A flight simulator was set up with visual representation of aircraft attitude, rate of climb, stability, and so on, and included engine noise inputs. A considerable amount of " flying" was done on this rig by the test pilots, before actual flight.

Fuel System Rig
  A full scale rig representing half the complete aircraft fuel system was built and mounted on a special gantry on which the specimen is pitched and rolled to simulate all attitudes of the aircraft in flight. All components of the fuel system were installed so that their function would be similar to that experienced in flight. Vacuum pumps were available on the rig to simulate altitude conditions. Tank pressurisation was provided, and a large heater to elevate the fuel temperature, to check flows under hot fuel conditions. This rig was also used for qualification testing of the various items in the fuel system (Fig. 18).

Air Conditioning System Rig
 This rig was provided to check systems functioning and the mass flow distribution throughout the system. The rig represents the complete air conditioning system, the cockpit being represented by an air tank of equivalent volume.
 The rig had to be totally enclosed because of the high noise level. Air temperatures at 30 locations in the rig were recorded by thermocouples, and the air turbine speed was obtained from a magnetic pick-up, which in turn was recorded on special instrumentation. Fig. 19 shows the rig before completion.

Other Tests
  A number of other tests involving the complete aircraft electrical system, the complete landing gear, the utility hydraulic system, and so on, were made. A system of insulating panels can be placed around most of the test rigs, and air is supplied through heat exchangers to raise the temperature to 250'F., or reduce it down to -65', by reversing the process. It was possible by this method to test the control system, structure, and so on, at the temperature conditions which apply throughout the flight envelope.
  The complete aircraft armament has also been the subject of an intensive test and development programme, and has involved considerable flight time on the CF-100's, which have been used as test vehicles for the Sparrow weapon programme at Malton, and at the U.S. Naval missile test centre at Point Mugu, California.

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

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