Report on Physical Effects of the Sonic Boom (1968) / Chapter Skim
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DISCUSSION
DISCUSSION
Pages 2-11
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From page 2... ...
The use of supersonic aircraft in overflight test programs is one way of acquiring sonic boom field test data on the nature of physical effects
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From page 3... ...
On the other hand, if there existed laboratory-type test equipment which simulated sonic boom forces in a controlled, reproducible manner, then test programs utilizing such equipment would provide scientifically valuable data concerning the physical effects of booms on materials and systems of construction. The argument for developing such equipment is strengthened by the fact that most boom amplitudes are smaller than are ordinarily considered to be destructive, and hence large numbers of repetitive loadings and samples are needed in order to generate extreme-value statistics required for application to the boom economic consequences question.
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From page 4... ...
Since it appears that the measurable response of many building materials and assemblages to impulse loadings may be independent of small variations in rise time of the pulse, it may be possible to relax the requirement that the simulator produce near-instantaneous rise times, at least for many types of specimen tests. And since it appears that the measurable response of assemblages having natural periods greater than the natural period of the applied pulse is independent of the details of the pulse profile and is mainly determined by impulse, the requirement that the simulator produce truly N-shaped waves may also be relaxed.
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From page 5... ...
6. Plastic materials, particularly extruded polyvinyl-chloride panels and similar thermoplastic building materials at low temperatures.
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From page 6... ...
Data in manufacturers' technical reports tend to be inadequate and misleading for analysis of small-probability boom damages. Supporting test data have been reviewed in detail, and, although it is possible to correct the gross difficulty by use of different statistical models, such as log- normal or Weibull distributions, there are test sampling problems which require further laboratory work.
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From page 7... ...
The first could be the most expensive if pursued in great detail, but a man-year effort plus specimen and apparatus costs would appreciably advance the state ot knowledge about glass and would materially improve boom damage predictions. Theoretical research into failures should be supported to the extent of about a man-year of effort.
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From page 8... ...
The Subcommittee on Physical Effects wishes to emphasize the fact that the probability of serious material damage being caused by a sonic boom generated by an aircraft operating in a safe, normal manner is very small. Logic suggests that measured characteristics of all sonic booms are not normally distributed and have some degree of truncated upper and lower bounds, and that such bounded distributions have different skew characteristics for different aircraft, flight conditions, over-pressures, periods, climates, and geographic locations.
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From page 9... ...
Detailed wind recordings should be made in several urban areas and close to buildings so that truly effective gust distributions can be compared with the large body of "airport-type" wind data. From these, an estimate of window and plaster damages caused by storm wind gusts can be produced.
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From page 10... ...
Such a group might be appointed from appropriate professional associations such as the American Society of Civil Engineers and the American Bar Association. Noise Recorders In the future, should commercial supersonic flights be scheduled over populated areas, as opposed to over-ocean flights only, some type of boom-monitoring system may be needed.
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From page 11... ...
It is recommended that several competent companies specializing in Jnstrumentdata-recording-and-retrieval systems be contracted to study means of accomplishing a national recording network for monitoring sonic booms. (An estimate of each study contract is $50,000, with time duration one year.)
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