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Jim Floyd:RAeS Lecture

Jim Floyd:
RAeS Lecture pg 9

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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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Go Up

 

Crew Escape System

  A considerable amount of development was carried out on the crew escape system, especially in view of the two-man crew requirement. We have estimated from simulated escape sequences that the completion of escape takes an average of approximately 8 seconds, from the time the pilot begins to order the observer to escape, to the point at which both men are clear of the aircraft.
  Crew escape time checks and tests were made on one of the Arrow mockups, and full scale ejections were made from the cockpit of the static test aircraft, using a dummy (Fig. 20). Film records indicated that the dummy's legs fouled the instrument panel during ejection, but it was considered that the behaviour of the dummy had not been entirely representative of that of a live occupant, and additional tests were made at the R.A.E. by the Martin Baker Company, with satisfactory results.
  Ejection from the Arrow is completely automatic. The pilot pulls the seat blind, this first triggers the canopy mechanism and, when the clamshell canopy has reached its full travel, the seat automatically ejects, and the pilot is later ejected automatically from the scat.
  To improve the time of ejection, we are now considering a linked escape system, with the pilot ejecting both the observer and himself from one control, which we estimate would cut down the escape time to 2.5 seconds.
  It is also proposed to carry out ejections from a supersonic rocket sled to demonstrate as fully as possible that the emergency canopy opening and crew ejection mechanisms function correctly, and that crew members can be safely ejected clear of the structure over the full flight envelope.

 

Wind Tunnel Tests

  It would be impossible in a relatively short paper to deal adequately with our wind tunnel programme, which involved some 4,000 runs and 4,000 hours of tunnel time at various facilities in Canada and the United States, including the Ottawa tunnels of the National Aeronautical Establishment, the Cornell Laboratories at Buffalo, the N.A.C.A. Langley Field and Cleveland tunnels, and the supersonic tunnel at the Massachusetts Institute of Technology. Fig. 21 lists the major tests made up to the present time. The amount of data collected, especially on basic aircraft stability, was enormous.

Ground Support Equipment

  In the early stages of preliminary design, it was decided by the R.C.A.F. that the ground support equipment should be designed concurrently with the basic aircraft, to allow the squadrons to be trained and equipped well ahead of the receipt of operational aircraft. It was also realised that with an aircraft of the complexity of the Arrow this equipment would, in any case, be required when the first few aircraft started their flight test programmes.
  A ground support design group was set up over three years ago within the Engineering Division to design those items required for satisfactory operation of the aircraft, and R.C.A.F. personnel joined this group to form a team which would evaluate and resolve the equipment received for the service readiness hangars and general turn-around equipment. A typical case is shown in Fig. 22.
  Studies were made on maintenance facilities and, as the design progressed, a number of conferences were held on the engineering mockups to establish the times of replacement and inspection of every equipment item on the aircraft. This group also prepared a proposal outlining a method for providing the personnel and skills required to maintain the complete Arrow weapons system, including the organising of maintenance personnel and recommendations for training programmes for ground crews.

Policy of Manufacture

  Our programme of building on the CF-100 had been carried out by the conventional method of building two prototype aircraft with minimum tooling, then building 10 pre-production aircraft on harder tools and, on the 13th aircraft, going into full scale production on relatively sophisticated tooling. Our timing, from the start of design in 1946 to delivering the first production aircraft was approximately six years.
  On the CF-105, it was obvious from the outset that, based on its greater complexity, even the first aircraft could not be built by hand methods and a certain amount of fairly hard tooling would be required. In addition, our schedule was to be very tight, from the time of initial design, to delivery to R.C.A.F. squadrons.
  In considering the method to be followed, we were also aware of the change in philosophy which was taking place in the United States on the basis of the Cook-Craigie recommendations, which provided for elimination of prototypes and experimental drawing and tooling, the first aircraft being built from production type tooling, and from production drawings.
  However, the manufacturers who had followed this philosophy at that time had previously had either research aircraft of the general configuration of their production vehicle, or had, in fact, built prototypes before going ahead with a production article. For instance, in thecase of the F.102, considerable development work had been done on the XF-92 research vehicle, and two prototypes had been built before going into full production on the F.102, whereas we had a completely new and complex aircraft, without the benefit of a research vehicle, and the engineering gamble which had to be taken, due to the gaps in our knowledge, was formidable.
  On the other hand, there did not appear to be time to build prototypes, develop them, and then re-issue production drawings incorporating the changes found from development.
  The decision was made, therefore, jointly between the Company, the R.C.A.F., and the Canadian government to proceed with a number of development aircraft on the basis of a production type drawing release from the outset. In other words, it was decided to take the technical risks involved to save time on the programme.
  Production personnel worked along with the Design Office to check and advise on produceability as the design went along. Detailed layouts, part prints and material specifications were all issued on a full production basis. Drawings were made full scale on glass cloth or vinyl transparencies to assist checking and allow these drawings to become masters for tooling templates, and so on. Full scale plastic templates were made up from the initial lines lofts, to be used as references and tool patterns by Manufacturing. Permanent type tools were made up throughout the build of assembly jigs, sub-assembly jigs, and detail tools. Fig. 23 (a) shows the main assembly jig and Fig. 23(b) shows one of the large milling machines purchased to mill the inner wing skins.
  A full scale metal mockup was made from the detail tools as they became available, and this mockup acted not only as a tool proving device, but was also used to train the production crews who were to build the first flying aircraft, and was used by Engineering as a check, and later, as a development tool. Where the correct material was not available, many parts of the mock-up were made from soft material, and some parts were made by hand to bring it up to a state of completion a little earlier than would have been the case if we had waited for permanent tooling. While every attempt was made to keep this mockup up to date with all changes, this happy state was never achieved, since the first aircraft was coming along fairly quickly behind the metal mockup.
  I will not pretend that this philosophy of production type build from the outset did not cause us a lot of problems in Engineering. However, it did achieve its objective, and has provided us with more development airframes on which to do development flying and checking.


FIGURE 23(a). Arrow main assembly jig. FIGURF, 23(b). Machining Arrow wing skins.

  In examining the number of aircraft to be used in the test programme, we were again very conscious of the time element, and it was obvious that we would need a relatively large number of aircraft to obtain the development flying necessary on the airframe, engine, fire control system, and armament.
  The Air Force examined the programmes which had been carried out in the United States, to ascertain the approximate number of flying hours required in a contemporary development programme. However, on examination, it was obvious that Canada could not afford to go for such an extensive programme, with up to 50 development aircraft, and a compromise was made with 15 aircraft being established as straight development vehicles for the various components, with an additional 21 aircraft for the R.C.A.F.'s evaluation programme, before these aircraft went into operational service. The portions of the programme for which these aircraft will be used is shown in Fig. 24.

Flight Test Programme

  The first engine running in the aircraft took place on 4th December 1957, taxi trials were started on Christmas Eve, 1957, and the first flight was made on 25th March 1958.
  Stage One of the flight test programme on the first aircraft covered the period from first flight until the 23rd April 1958, i.e. the first 29 days of flying, during which nine flights were made.
The first two flights were for pilot familiarisation, the aircraft flew super- sonic on the third flight and, on the seventh flight, reached a speed well over 1,000 miles per hour at an altitude of 50,000 ft. in a climb while still accelerating.
  Most of the early flying was done by Jan Zurakowski, Avro Chief Development Pilot. The aircraft was also flown by F/Lt. J. Woodman, R.C.A.F. Evaluation Pilot, and "Spud" Potocki, Avro development pilot
  Most of these flights, beyond the third, were at supersonic speeds, but the aircraft was not flown to it's, maximum speed capability at any time during these early flights.
  Practically all of the flights have been made at weight considerably in excess of the mission weigh estimated for the Mark 2 operational aircraft, since the installed weight of the J.75 engines is higher than the installed weight of the Iroquois, and ballast is also required in the nose to balance this extra weight Average take-off weight has been around 67,000 lb., and landing weights have been in the order of 54,000 lb.
  Basically, this first series of tests were to evaluate the general handling qualities of the aircraft over as much of the flight envelope as possible, to evaluate the flying control system and damping system, to check instrumentation and telemetry techniques, and to check safety under adverse conditions, such as one engine throttled back, induced oscillations, and so on.

  The following comments were extracted from the pilots' reports:-

  • The nosewheel can be lifted off by very gentle movement of stick at just over 120 knots.

  • Unstick speed is about 170 knots A.S.l., with an aircraft attitude of about 11deg.

  • Acceleration is rapid, with negligible correction required, and no tendency to swing.

  • Typical touchdown speed is a little over 165 knots (the normal landing procedure is to stream the drag chute on touchdown when the nosewheel has settled).

  • There was no indication of stalling at the maximum angle of attack at 15deg.

  • Stability steadily improved with speed.

  • Change of trim was negligible except in the transonic region, where small changes of trim were required.

  • No attention was required by the pilot to prevent over-controlling.

  • In turns, stick force was moderate to light, but always positive with no tendency to pitch up or tighten.

  • In sideslip, the aircraft was a little touchy with-out the damper, but excellent with damper switched on.

   To quote the pilots, " In general, the handling characteristics and performance of the aircraft agreed well with estimates."
  This series of flights provided an excellent start to, our flight test programme. After the Stage One flying, the first aircraft was given a thorough inspection and was flying again on 7th June on Stage Two Testing. On the 11th flight on 11th June, we had an unfortunate accident due to a failure of the undercarriage, which put the aircraft out of commission for several months.
Because of the excellent photographic coverage which we obtained of the accident, we were able to assess the cause very quickly. The aircraft had touched down with the port leg twisted, and was in this condition during the whole of the 4,000 ft. run. I have included some of these photographs as a matter of interest.

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

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