Avro Arrow-An Aviation Chapter In Canadian History pg2

Paul Campagna, P.Eng.

PAGE 1	PAGE 2	PAGE 3
Introduction	Fuselage	Engines
Company	Weapons Carriage	Problems
Aircraft	Landing Gear	Consequences
Wing	Fly-by-Wire	Why was the Arrow Cancelled?
	Setting the Record Straight: The Designer's View by Margaret McCaffery	"A Flawed Plane and an Inept Corporation"? The Historian's View by Margaret McCaffery

Acknowledgements

References

Drawing: DND

AVIONICS ARMAMENT EQUIPMENT ENGINE FUEL

The Fuselage
The aircraft was extensively "area ruled." This concept involves aerodynamic shaping of the cross-sectional area of the fuselage along its length, to reduce drag to a minimum. Also called the "Coke bottle" design, the fuselage is characteristically pinched at the waist at the wing joint, although this was not immediately noticeable on the Arrow.
   Similarly, the cockpit was designed as an extension of the fuselage rather than as a separate bubble, again for good aerodynamic performance. The cockpit canopy itself was of unusual design, opening and closing in clam-shell fashion due to its size and weight, as well as for case of entry and exit. The canopy was made of a magnesium alloy with partly glazed glass. In back, drag was reduced by trailing the canopy off into a spine running the length of the aircraft to the tail, This also doubled as a conduit for controls and wire cabling. In short, everything possible was done to reduce aerodynamic drag, including the internal carriage of weapons.

The Weapons Carriage
The concept of internal weapons carriage has spawned several misguided criticisms about an aircraft that would destroy itself if the weapons package were lowered during supersonic flight. In fact, the weapons package was designed to be lowered and removed only while on the ground. In this way, a fully loaded package could be "snapped" into place, considerably reducing the turnaround time per aircraft. This concept also allowed easy reconfiguration for other roles, including reconnaissance and bomber. The pack was never designed to be lowered in flight; since it was 16 feet long and nine feet across, lowering in flight would have been ludicrous. At no time were any of the completed aircraft fitted with weapons.
   Initially, the Arrow was to have carried the Hughes Falcon guided missile. The Falcons were to be re- placed by Sparrow 2D missiles, with a sophisticated weapons control system known as ASTRA. However, Avro engineers judged the Sparrow missiles to be inferior for use in a high performance aircraft without further development.
   Each missile was to be mounted on its own hydraulically activated retractable launching mechanism. Be- cause of their large fins, Sparrows would sit partially within and partially outside the belly of the aircraft. (This is similar to the manner in which missiles are carried on the Tornado aircraft: they are recessed into the underbelly; however, no retractable launcher is required.) The smaller Falcon missiles would have been fully internal to the aircraft. Missiles would extend from their own individual bay doors. Aft missiles would be fired first, followed by forward missiles.(2) A sliding bay' door arrangement was being considered for the Sparrows. Door opening or closing was to have been completed in 0.35 seconds; extension was to have taken another 1.25 seconds or less.
   It has been argued that no other fighter has duplicated this internal weapons carriage. This is simply not the case. The CF-101 Voodoo aircraft, for example, employed a rotating platform, which carried some of the weapons internally and the remainder externally. The F-106 Delta Dart used an almost identical internal missile system to that of the Arrow. Internal weapons carriage may also become the future norm.
   As calculated by Avro engineers, externally mounting four missiles could have increased drag by some 20% at Mach 1.5. Bill Gunston (3) states that the move towards faster, more agile fighters is slowly forcing the removal of externally mounted weapons in order to take every advantage of the resulting reduced drag. He states it will simply no longer be good enough to hang missiles on pylons. One solution is to use the recessed method of missile carriage and the other is to place weapons in an internal bay.
   A recent article (4) describes stealth design techniques to reduce radar cross-sectional (RCS) area. These include using aerodynamic shapes such as delta wings, blending cockpit and wings into the fuselage and, of course, carrying weapons internally. Aerodynamic and stealth efficiency appear to be complementary design requirements. The Arrow was not a stealth aircraft, but obviously the concept of a "clean" aircraft could have several inherent advantages.

Setting the Record Straight: The Designer's View
                                      Margaret McCaffery

" I feel for the youngsters. In our day you could get on with the job and not worry about going over the precipice." Those hardly sound like the words of a man who has known overwhelming disappointment in "getting on with the job," yet they capture the spirit of the man who designed the C-102 jetliner-which the New York press claimed "licks anything of ours" -was vice-president of engineering for Avro Aircraft when it was building the CF-105 (Avro Arrow), and ended up consulting on production of the Anglo- French Concorde.    James C. Floyd, P.Eng., epitomizes the cheery "mustn't grumble" attitude of his native Manchester, yet he's a proud Canadian, who retired to this country after spending 20 years working in Britain following cancellation of the Arrow and the crumbling of A.V. Roe Canada. His concern for "the youngsters" has led him on a concerted campaign to set the history books straight if possible, and if not, well, he's written one of his own.(1) He is currently helping to set up the Canadian Aerospace Heritage Foundation which aims to build a full-scale replica of the Arrow and other Canadian aircraft for permanent exhibit.      What does someone who was responsible for the design of the Avro Arrow think about the criticisms of its abilities? Jim Floyd and other Avro engineers have expressed themselves eloquently to the publishers of Professor Morton's books, but he sees this kind of misinformation as part of a larger picture:    "High technology is, by its very nature, difficult for the layman or voter to adequately assess, and its worth and impact can only be fully appreciated, even by those who have to ensure its survival, if it is properly and compre- hensively presented. In the past, Canadian engineers have tended to adopt a low profile in the political arena and have rarely been consulted about the long-term effects of the decisions made by the 'captains of industry' or their political counterparts. As an example, I firmly believe that had Mr. Howe been exposed to a proper and full-scale engineering briefing on the Jetliner project, he would not have made the utterly erroneous statements about the alleged technical shortcomings of the aircraft, which must have influenced his decision to abandon the project and which later caused him considerable embarrassment, even within his own party."'    Although he refers to himself (with a twinkle in his eye) as "just a poor engineer" who doesn't know anything about politics, he was embroiled in the Cold War politics of the late 1950s by his involvement with the Arrow. In this interview with Engineering Dimensions' editor Margaret McCaffery, he relives those days at Malton. ED.. Why do you think Diefenbaker cancelled the Arrow? Floyd: Diefenbaker had the worst advice possible. His main advice came from General Pearkes, who was a brave old soldier, but he didn't know anything about airplanes at all. He'd been hoodwinked by a visit to the States where he was told that airplanes are out and missiles are in and there'll never be another manned airplane bought by any air force. ED: Was it on the strength of that advice alone that Diefenbaker acted? Floyd: Oh no. It was such a complex picture, it was like a tree: even the leaves had something to do with it dying. There were four major reasons: 1 Diefenbaker could see the costs of the Arrow rising. It isn't unusual for the costs on high technology to be going up all the time; one of the prime examples would be the Concorde, which by the time it flew cost more than double what it had been estimated at. The Arrow was going the same sort of way. 2 General Pearkes had said we can only justify this sort of a cost if we could sell it to the Yanks or the Brits. So he went out, completely prematurely, because you never sell an aircraft to a foreign government before you've de- veloped it yourself, and of course he came back with a no. 3 Then there's this memorandum Paul Campagna brought back from Washington (see p. 51). It's obvious that the Americans had virtually insisted on the cancellation of the Arrow

as part of this deal, long before Diefenbaker came out and said that the Arrow was can- celled. That's a new one to me. 4 Then the Americans were cutting down on their development of manned airplanes. Although they'd put out a specification for the F-108, which was a very highly supersonic airplane, probably as near to the Arrow as you can get, they'd cancelled it, because they weren't too sure that manned aircraft would be needed. The British government had put out a White Paper saying that they didn't foresee that there'd be any fighter aircraft designed from that point on. So I really don't blame  Diefenbaker for his uneasiness looking at the program. I would blame him, though, for the way he accomplished the cancellation. ED: Did you suspect that the program was going to be cancelled?  Floyd: We suspected that there'd be some hiccup. In September 1958, we were told that the whole thing would be reviewed in March, so of course we were on tenterhooks. But the appraisal was done on February 20 and the can- cellation came the same day. That was the biggest shock of the century. We were in a board meeting with John Plant (president of Avro Aircraft) trying to settle some very mundane union situation about seniority Joe Morley (sales and service manager) came running down the corridor with a man from the DDP (Department of Defence Production) saying they'd heard on the radio that Diefenbaker had cancelled the Arrow. ED. So you heard about it at the same time as the general public? Floyd: Later than the general public--- they heard it on the radio. ED: It sounds like the government had a gun to its head. Floyd: We were told to close everything down and that nothing would be paid as from that day. My first thought was to see if any of our other projects could be got into shape so I could keep my 1,500 engineers. I'd been pleading for years to get another project going at the same time as the Arrow, but Fred Smye (general manager), who was a most sincere man, felt we had a duty to do the best we could on that airplane. ED: I still find it very difficult to understand why it was ordered scrapped, especially when today we're all talking about technology transfer, joint ventures, etc. Floyd: You're in very good company, The first thing that I did was to get on to the RAE (Royal Aircraft Establishment)  in the UK to see if they'd be interested in taking some of these airplanes and they said of course, provided we could back them up with parts. Well, we had 31 aircraft back through the plant in different stages of production, so we had plenty of parts. We'd even worked out a method of transportation over the northern route and then the order to scrap came down. (This was mid-April 1959. Floyd had been ordered to scrap the Jetliner, his admitted favourite project, on November 23, 1956. Three years later, after setting up another first class design tearn at Hawker-Siddely, UK, where he led the feasibility study on the Concorde, Jim Floyd experienced the disappointment of seeing the design study for Concorde go to Bristol Aviation Corporation. Saying he didn't want to see another aircraft, he quit and took his family on vacation. On his return, his first call was from the minister in charge of the Concorde asking him to consult on the project. That one flew!) ED: What message would you have for today's engineers? Floyd: The best things I've learned have been about dealing with people to bring out the best in them. The old things I learned in England I rebelled against. I try to coax people rather than beat them over the head. Canadians are very flexible: treat them the right way and you can get anything out of them.    One of the things I'm trying to do with the Canadian Aerospace Heritage Foundation is to help young people get the incentive to do some of the things we tried to do. Today there seems to be an apathy, a sense of too many things in the way. I'd like to give the kids some hope. Reference 1. Floyd, J. The Avro Canada C-102 Jetliner, Erin: Boston Mills Press, 1986.

Photo: J.C. FLOYD, P.Eng.
Avro Arrow design team, left to right. Bob Lindley, chief engineer; Jim Floyd, vice president, engineering;
Guest Hake, Arrow project engineer, and Jim Chamberlin, chief, technical design.

The Landing Gear
The requirement for such a large weapons bay necessitated stowage of the main landing gear in the thin delta wings. This caused a number of engineering difficulties, overcome by Dowty Engineering Limited. On retraction, the main gear would be shortened, angled forward and then twisted in order to be accommodated Given the 30-ton weight of the aircraft and resulting 200,000-ib compressive load on the main gear on landing, ultra-high-tensile steel with an ultimate tensile strength of 260,000-280,000 psi was required. Use of aluminum was obviously precluded, as was the use of butt and gas welding techniques. Instead, large forgings were made, using a die process. For example, the main outer leg was the largest forging, weighing 1,000 lb. After machining this would be reduced to 167 lb. Solutions to the problem put Dowty and Avro engineers at the forefront of metallurgical research.
   Likewise, the engineers at Jarry Hydraulics were obtaining patents for their steering mechanism in the nose gear arrangement, among others. In fact, Avro engineers and their subcontractors made enormous strides in developing high temperature alloys, high pressure and high temperature systems, fuel technol- ogy for supersonic flight and human engineering, in terms of cockpit layout and design. These techniques pushed the world aircraft industry further ahead. In support of these advances, Avro maintained a huge metal-to-metal autoclave, a special heat treat furnace, a giant skin mill and a 15,000-ton rubber pad forming press (then the largest in the world).

Fly-by-wire
Early in the design, it was decided that some form of power assist would be required to help control and fly the aircraft during supersonic flight. The chosen result was fly-by-wire. In conventional systems, the pilot's stick and rudder controls are mechanically linked via steel cables or rods to valves which control high pressure fluid flow to the actuators. These powerful hydraulic actuators, in turn, operate the aircraft's control surfaces, such as elevators and ailerons. In military aircraft, automatic flight control systems, gyroscopes and position sensors are also mechanically linked to the actuators through the control rods.
   In the Arrow automatic flight control system (AFCS), in automatic mode, the pilot's stick and position- ing sensors were linked electrically to electro-hydraulic actuators. Hence, stability, command and control were effected almost instantaneously in all three axes. Analogue computers with a mix of vacuum tube and transistor technology were used, together with autostabilization of the tail fin and artificial feel, to give the pilot some sense of force on his control stick.
   Not until the 1970s did fighter planes use a similar AFCS, although variations had been employed in experimental aircraft and the SR 71 Blackbird. The F-16 and Panavia Tornado both used analogue fly-by-wire.The first fighter to replace the analogue system with digital electronics was the F/A-18 Hornet.
   How effective was the Arrow fly-by-wire automatic flight control system? According to test pilot Spud Potocki, in a 60-degree climb, with full afterburner, he would shut down one engine and experience no expected sideslip or roll. The AFCS would compensate instantaneously. Automatic approaches and takeoffs were also successfully completed. The Arrow was the most modern interceptor in the world, clearly over 20 years ahead of its time.

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