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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

Fire Protection

                 With the engines installed, the nacelle is divided into two compartments on each side, and a third compartment rousing the accessory gearbox. This split-up is achieved by means of special, firewalls and bulkheadsFIG 8 as shown in figure 8. Each nacelle has a vertical firewall forming a centre keel and isolating the two engines from each other.

                 The engine has an integral intermediate firewall permanently attached and sited around the combustion chambers. This mates up with a permanent portion of firewall on the nacelle foming a complete firewall between the hot and cool portions of the engine.

                 The front portion, or zone 1, which also forms the plenum chamber contains the engine accessories and oil tank etc., while the rear portion or zone 2, contains all the hot portions of the engine, combustion chambers, turbine casing, and jet pipe. The intermediate firewall is to prevent the high pressure fuel from a burst pipe or joint being sprayed on to the hot side.

                 The rear portion of zone 2, extends in the shape of a tunnel back to the jet nozzle and is completely lined with stainless steel firewalling and sealed against ingress of fuel or oil.

                 Fire from a burst combustion chamber or perforated jet pipe would be confined within this zone out of reach of electrical and fuel lines or the aircraft structure.

                 The above system of firewalling also isolates all engine parts from the accessories and gearbox, which are in the space above the conical firewalls, shown on figure 8, as zone 3.

                Edison resetting type fire-detectors are used and a methylbromide system of extinguishing is used for zones 1 and 2, while a C02 system is provided for the gearbox compartment, zone 3. A two-shot system is used and the warning lights, buttons, and selector switches are mounted on the ceiling fire-protection panel in the cockpit.

Thrust Augmentation

              The thrust from a jet engine varies considerably with temperature and airport altitude, and on a hot day FIG 12with a temparature of 110 deg F, the reduction in jet thrust can be as much as 16%. As this can be critical for take-off conditions, where a possible engine failure has to be taken into account, some means of thrust augmentation has to be used.

                Various means of achieving the extra thrust were investigated, and it was finally decided that injection of a water-methanol mixture into the compressor inlet offered the best solution. The predominant effect of this is to increase the mass flow of air to the engine by increasing the air density at the compressor inlet.

                 The injection system itself is relatively simple, and has few of the disadvantages of other forms of augmentation such as, after-burning where the long sheets of flame coming out of the tailcone are likely to cause alarm to the passengers. The percentage increase in thrust with rate of injection is shown in figure 12.

                It can be seen from the graph, that under tropical conditions, to provide the static thrust which would be obtained for take-off under standard I. C. A. N. conditions, it is necessary to inject the mixture at a rate of 10FIG 13 gals. per minute.

                 A tank is housed in each nacelle holding 66 gals. of water-methanol, which is sufficient to supply each engine vdth the required quantity for a period of three minutes.

                 Figure 13 shows the take-off distance for various gross weights and temperatures.



"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."
Scott McArthur.




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