ANSWER 1: “The structural design of the Iroquois, providing a thrust to weight ratio of over five, yet retaining a high degree of structural reliability, ruggedness, and simplicity, was a considerable state-of-the-art advance. The oil lubricating system of the Iroquois was completely novel, incorporating a wholly internal air venting system requiring no overboard connections, and ensuring adequate internal pressure to prevent circulating pump cavitation at low ambient pressure conditions, i.e. high altitudes. Root fixing methods and design aspects of plastic blades was new. The design of compressor blade attrition seals and the mechanical aspects of shrouded stators and labyrinth seals was advanced. Right after cancellation other engine manufacturers wanted this information. Industrial turbines were made more competitive through work done on turbine blade cooling. Heat transfer and fabrication problems were solved. The various configurations, investigations and reasons for final choices and relatively simple design could be of great interest. At a fairly late stage in the development of the Iroquois, a completely new problem was encountered, that of aerodynamic stimulation of compressor/turbine blade vibration. Work on this problem will be of interest to others in the field. (Authors note: Recall that Grinyer told me that 7^th stage compressor blades were failing toward the end of the programme…the problem of operational stimulation of vibrational forces leading to blade failure was what he was worried about.) It is impossible to guarantee that a compressor will never throw a blade. At Orenda, during the course of the Iroquois programme, methods and design of ballistic protection for surrounding structures was advanced. Blade root fixture failure received intensive investigation. Results of work done to alleviate this problem involved, for example, fret welding, shot peening and lubrication will be of interest. It was found that textbook approaches to operations at critical speeds fell far short of reality. For example bearing flexibility at high speeds was investigated and new solutions found. The operating experience and design methodology of the rear, high temperature, end of the Iroquois will be of interest to those concerned with dimensional stability and structures operating in this regime. The self-squaring after-burner nozzle was a breakthrough, and has potential interest because of its contribution to hydraulic system simplification.”

Source:

Arrow Countdown,

pg. 48 (Zuuring)