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Avro Jetliner

AVRO C102 Jetliner
North America's First 1949-1956

This republication has been made possible thanks to the assistance of
The Society of Automotive Engineers
and Dr. James C. Floyd. This is quite a lengthy lecture and was presented in January 1950. We hope you enjoy this piece of aviation history.
Scott McArthur. Webmaster, Arrow Recovery Canad
a

 Fuel Tanks

                  The scaling of the integral tanks was a problem which had to be studied very carefully, since the airlines had been having some trouble with certain types of integral tanks and a certain amount of prejudice had been built up against them.

                  After much investigation and testing, a system of sealing was derived which has given such excellent results on test that it appears to be a very great improvement on the existing methods of sealing.

                  Thiokol-based sealants are used and combinations of plasticizers and synthetic resins are added, FIG 17making a permanently plastic seal, which has low shrinkage and good adhesion properties. The top and bottom wing skins and the spars are sealed before assembly, and the corners are then sealed after the wing is removed from the assembly jig.

                  No sealant is used between the faying surfaces. The finished tank is sprayed with a cyclohexanone solvent to bond the complete inner surface. The system lands itself to local repair as no slushing compounds are used

                  Access to the wing is by large leading edge access doors and stress-bearing removable panels in the front spar, see figure 17.

 FLYING CONTROLS

                   Double aerodynamically-unbalanced control surfaces have been used for both the rudder and elevator controls, see figure 18.

                  The intermediate or auxiliary surface on the rudders is used soley to trim out for an engine failure at low speeds. With the use of jet engines, high rudder angles are not normally necessary due to the absence of slip FIG 18stream, which is the usual cause of swing at take-off. The engines are also close to the fuselage which again reduces the rudder power required.

                 The tail plane is out of the flap wake during landing and, therefore, the tail efficiency is high which reduces the elevator angles required for normal trim. The auxiliary surface is only required for the flare-out, on landing with an extremely forward C. G. Piano hinges have been used on all tail surfaces, and this improves the effectiveness by sealing the gaps.

                 Narrow chord high aspect ratio surfaces are used, and these have the advantage that no aerodynamic balance is necessary. They also have lower drag, less danger of icing, better repeatability and low weight of mass balance.

                 The narrow chord elevator is also very much better from the point of view of susceptability to oscillatory instability. The usual cures for this are less aerodynamic blance, and a lower mass moment of inertia. These features are all incorporated in the double surface control.

                 Power operation of the tail surfaces on the first prototype is by a simple switch controlling a small electric motor and limit switches. The system is entirely separate from the electric and manual elevator trim.

                An hydraulic assister is used for aileron power boost in the ratio of 5 to 1. This is a pure assist system, and in the event of an hydraulic or unit failure, the booster is thrown out and full manual control is retained with, of course, reduced power.

                Push-pull type controls are used on all three main control systems, employing light alloy tube to eliminate differential expansion and contraction under extreme temperature changes. The tubes are supported in roller guide bearings using rubber covered ball bearing rollers.

 PRESSURIZING

                 The air conditioning system is entirely automatic once the controls have been pre set by the pilot. Either supercharger is capable of delivering about 60 pounds of air per minute up to an altitude of 13,500 ft. Automatic control of the cabin pressure is maintained by the discharge valve set to provide sea level conditions up to 21,500 ft.

                At 21,500 ft. the differential pressure remains constant, and at 25,000 ft., the cabin altitude is 2000 ft. and 4,000 ft. at 30,000 ft. altitude.

                 The rate of pressure change in the cabin during the climb and descent is also automatically controlled.

Cabin Sealing

                  The fuselage had to be very carefully sealed to provide a pressure tight cabin and a method of FIG 19sealing was used which has been well tried on other aircraft.

                This consisted of applying special sealing compounds between the faying surfaces and skin joints. The remaining riveting such as, riveting stringers and capping strips to the skin were not sealed, as with the use of dimpled riveting, the rivets are tight enough to produce a satisfactory seal. Any leaking rivets are individually sealed by bushing with a special sealant.

                 Figure 19 shows the cabin insulation installed prior to fitting the wall panels.

 COCKPIT LAYOUT

                 Having in mind the usual confusing array and disposition of instruments and controls in the average flight deck, a special attempt was made in the case of the C-102 to achieve a configuration that was both functionally good, and at the same time, gave the best servicing layout.

                 The extent to which this has been achieved can be seen in figure 20. The main instrument panel is divided into three sections. The centre panel carries all engine and fuel instruments. A small fuel system control panel is attached to the engine panel with the fuel diagram etched on, and this contains the switches and lights FIG 20for the various booster pumps and cross-feed warning lights. All panels are hinged for easy access.

                 The engine instrument panel is very much simplified by the use of jet engines, as the only engine instruments are the R. P. M. indicators, jet pipe temperature gauges, burner pressure gauges, and oil pressure warning lights.

                 The two main instrument panels carry the normal flight instruments, and have been grouped to conform with the latest requirements for radio navigation and automatic landing aids.

                 In the ceiling, between and within easy reach of each pilot, is the main electrical panel carrying the engine starter switches, fire protection switches and buttons, and the main electrical control switches.

                 The pressurization control panel is on the left of the captain and the air conditioning, oxygen and de-icing control panels to the right of the first officer. Circuit breaker panels for both electrical and radio equipment are mounted on the aft deck bulkhead.

                  Both pilots' seats are fully adjustable and slide back for easy access. Cranked control columns are used to avoid obstruction to the pilots' knees, and a spectacle type of aileron hand wheel is used.

                  A lot of thought was put into the main control pedestal, which on the upper portion carries the engine throttles, undercarriage, flap, and automatic pilot controls, the emergency manual low pressure fuel cock levers, and fuel tank selectors.

                  The radio control panels are situated on the lower portion of the pedestal. The pedestal also carries all the manual trimmer controls, the manual autopilot disconnect lever, gust lock and parking brake levers, and the aileron power boost cut-out.

                  Direct vision windows which swing inwards are provided for landing under adverse weather conditions.

                  The rudder pedals are fully adjustable and are articulated to provide  two brakes for equal or differential brake application.

                   The above cockpit layout was finalized only after many conferences with airline pilots and technicians and the final mock-up was carefully checked to get the best possible layout.

"Copyright 1951 Society of Automotive Engineers, Inc. This paper is published on this web-site with permission from the Society of Automotive Engineers, Inc. As a user of this web-site, you are permitted to view this paper on-line, download the pdf file and to print a copy at no cost for your use only. Downloaded pdf files and printouts of the SAE paper contained on this web-site may not be copied or distributed to others or for the use of others."
CONVERTED TO HTML, AND HYPERLINKS ADDED, January 17, 2002.
Scott McArthur.

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