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Presidential Address: Navigation in Aerial Commerce

Published online by Cambridge University Press:  21 October 2009

Extract

Whatever the word ‘navigation’ is taken to mean, it must, etymologically, be something one does to a ship. What a pity that the name ‘airship’ was given so early in the evolution of aviation to its dinosaurs! The modern airliner is truly a ship of the air. There was a move, half a century ago, to coin the word ‘avigation’ but, apart from the obvious retort that, if ‘navigation’ is of ships, ‘avigation’ is strictly for the birds, the term ‘air navigation’ had already been established by the International Convention on Air Navigation and the Air Navigation Acts by which Parliament legislates on aviation in general and its commercial application in particular.

Type
Research Article
Copyright
Copyright © The Royal Institute of Navigation 1986

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References

NOTES AND REFERENCES

1 An extant copy of the sailing directions is dated January 1296 by the copyist. See Motzo, B. R. (1947) II Compasso da Navigare, Cagliari-Universitá.Google Scholar
2 It has been observed that men are rarely so innocently employed.Google Scholar
3 Cf. Goedel's theorem in mathematics and the Indeterminancy Principle in physics.Google Scholar
4 The construction in Fig. 4a is not rigorous. A spheroidal triangle cannot be similar to the triangle of velocities.Google Scholar
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6Fraser, D. O. (1948). The elementary theory of pressure pattern flying. This Journal 1, 40.Google Scholar
7 Balloons may be navigated but they cannot be steered.Google Scholar
8 Least work is done against drag by flying at such an angle of attack that the ratio of the coefficients of lift and drag (CL/Cd) is a maximum. The corresponding indicated air speed (Kimd) is ✓(weight) × a constant which depends only on aircraft geometry at least at Britannia speeds, less than 50 per cent of the speed of sound. Because 20 per cent of the Britannia's power was jet thrust, maximum efficiency was thought to be at 1 06 V imd which corresponds to 0-487 √w. It is convenient to think of jet propulsion as producing thrust rather than power per unit fuel flow. If thrust specific fuel consumption variation is ignored it is easy to show that the condition for maximum range for a jet is MC 1/C d = max. where M is Mach number. That condition is faster than Kimd.Google Scholar
9Alabaster, R. C. (1953). The operation and navigation of jet airliners. Figure 7 is reproduced from this paper. This Journal 6, 213.Google Scholar
10 Jet streams were not understood when the Comet I operation was planned. As reference 9 clearly implies, they were not fully prepared for the big variations in the optimum in both horizontal and vertical planes caused by the presence of jet streams.Google Scholar
11 Normally of course headwind increases the optimum speed (Mach number for maximum range of a jet may increase by 004 against a jet stream if constrained to one flight level). Headwinds also reduce the optimum altitude and at low altitudes max c.r.p.m. on a Britannia could produce speeds in excess of V no, a structural speed limit.Google Scholar
12 Figure 8 is reproduced from: Williams, J. E. D. (1957). Navigational aspects of turboprop operation on the North Atlantic. This Journal 10, 31. The trade off between fuel and time chosen by selecting an altitude is described by the slope of the weight isogram at its intersection with the altitude isogram.Google Scholar
13 By a bilateral agreement between the UK and the USA after World War II, the capacity to carry traffic between the two nations was divided equally between the carriers designated by each country who were required to offer a common fare structure approved by both countries. As the airlines of other nations started or re-started, these principles became generalized and so extended that the permissible content of an economy class sandwich became a matter of hot debate. Airlines therefore competed almost entirely in terms of aircraft type in an era of rapidly developing product quality, from the unpressurized, 180 kt, 2000 n.m. range DC4 to the Boeing 747 in 22 years. No one could afford anything but the latest. The consequent financial, economic and technical pressures had far-reaching and enduring effects on world transport as a whole and several other industries. There have been no comparable competitive pressures to solve navigation problems since all suffer equally.Google Scholar
14 The description of the rationale is taken from: Booker, P. (1979). Minimum navigation performance specifications in the North Atlantic area. This Journal 32, 357. For original mathematical analysis see: Reich, P. G. (1966). Analysis of long range air traffic systems, etc. This Journal 19, 88–98, 169–193, 331–347.CrossRefGoogle Scholar
15Parker, J. B. (1958). The effect of blunders on collision risk calculations. This Journal 11, 29.Google Scholar
16Hsu, D. A. (1980). Further analysis of position errors in navigation. This Journal 33, 452.Google Scholar
17 I have ignored Concorde which sadly accounts for perhaps 0 1 per cent of world air traffic.Google Scholar