This paper discusses the cost of high technology and the benefits to commercial air transport. The manufacturer's dilemma today is that whereas one could pay a 16% price premium to obtain a 10% reduction in fuel cost in the late 1970s, in 1985 that price premium has diminished to only 2½/2% to achieve a 10% fuel saving. Consequently, we must obtain the benefits of high technology at an extremely low cost.

Four areas are discussed in some depth: Aerodynamics, including the effects of computational fluid dynamics, wing design, and laminar flow. Structures, including the effects of new materials, both metallic and non-metallic, and the automated tools necessary to build the non-metallic structure. Avionics, including both fly-by-wire and fly-by-light, and the improvements due to high speed digital computers as well as flat panel flight deck displays. Propulsion systems, including the effects of high bypass ratio, high pressure ratio turbofan engines, and single and counterrotation turbopropellers. The final result is an integration of these four areas of technology into a composition transport aircraft and the resulting performance.

We all tend to think of the aviation industry as exciting high technology and eagerly look forward to the next new developments. Unfortunately, the air transport industry has just been through a most agonising depression on a worldwide basis, and their primary thoughts are, 'How can we keep those manufacturers with their new toys at bay until we can recover?' Certainly the manufacturers respect this view because we, for one, have just spent several billions to roll out three new products, and high technology has been expensive. To illustrate, if we compare the cost elements of a 727 of 1970 with one of 1980 (Fig. 1), we see the 68% increase in fuel cost (Fig. 2) that certainly drove the designs of the 757 and 767 airplanes. But if we look further at the cost element breakdown for a 1985 757, we see the large reduction in cash cost due to the high efficiency of its Rolls-Royce engine and the technology of its new wing, structures, and systems. What we often fail to perceive properly is the very large change due to the ownership cost of this high technology aircraft.

Large deflection analysis of a cantilever beam under a tip concentrated rotational load governed by a second order non-linear differential equation is solved using a fourth-order Runge-Kutta integration scheme. Initially the two point boundary value problem is converted to an initial value problem by estimating one of the two required initial conditions in an iterative process, so as to satisfy the other boundary condition. The details of load deflection curves are presented.

Free vibration characteristics of stiffened plates possessing symmetrical stiffeners have been investigated by the finite element method. The main elegance of the element used lies in that the formulation takes into account the arbitrary orientation of a stiffener inside the plate element. The element being isoparametric in nature caters effectively for the irregular edges of the boundary as well as the transverse shear deformation of the plate and the stiffeners. Rectangular and skew stiffened plates having various boundary conditions and with stiffeners varying in number and in spacing, have been analysed. The correlation of the natural frequencies obtained by the present approach with the published results have been found to be very good.

An analysis of an extensive series of unsteady and steady pressure measurements at transonic speeds on a rigid 12% thick NACA 16 series aerofoil reveals a useful classification of the type of excitation characteristics of particular flow regions.

The pressure fluctuation measurements suggest that when the shock from the aerofoil reaches the tunnel roof, serious interference (both dynamic and static) occurs.

The RAE 2 ft × 1½ ft Transonic Tunnel used for the tests has low levels of flow unsteadiness at low frequencies, making it a useful facility for basic research in time-dependent aerodynamics.