Abstract

This paper describes a method of measuring the apparent change in the intensity of a beacon as its rate of rotation is altered. The equivalent intensity of several beacons is plotted against the duration of the flash. It is found that Blondel and Rey’s law for abrupt flashes also seems to describe the equivalent intensity of service beacons to a first degree of approximation.

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  1. An investigation carried out for the Bureau of Air Commerce, of the U. S. Department of Commerce, by the National Bureau of Standards and described in detail in a report being issued by the Safety and Planning Division,Bureau of Air Commerce. Publication of this paper approved by the Director of the Bureau of Air Commerce.
  2. Publication approved by the Director of the National Bureau of Standards of the U. S. Department of Commerce.
  3. The word visibility, as used in this paper, refers to the capacity of a light source to stand out from the background,i.e., the contrast between the light source and the background. Other words which have this connotation are discernability, visiopia, and vis-ability. Visibility is chosen because it is the more common synonym and hence less likely to confuse the reader.
  4. A. Blondel and J. Rey, Comptes rendus 153, 54 (1911);162, 587 and 861 (1916); 178, 276 and 1245 (1924).
  5. H. Pieéron, Comptes rendus 170, 525 and 1203 (1920);178, 276, 966 and 1245 (1924).
  6. A. K. Toulmin-Smith and H. N. Green, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 26, 304 (1933).
  7. P. Van Braam Van Vloten, L'Éclairage des Routes Aériennes, Ve Congrés Internationale de la Navigation Aérienne (1930), p. 5.
  8. I. Langmuir and W. F. Westendorp, "A Study of Light Signals in Aviation and Navigation," Physics 1,273 (1931).280
  9. W. M. Hampton, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 27, 46 (1934).
  10. For Ec, near the threshold level, Toulmin-Smith and Green obtained k = 0.2 second. Therefore, a flash-duration of about 4 seconds would be required to give an apparentintensity ratio of 95 percent under these conditions.

1934 (1)

W. M. Hampton, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 27, 46 (1934).

1933 (1)

A. K. Toulmin-Smith and H. N. Green, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 26, 304 (1933).

1931 (1)

I. Langmuir and W. F. Westendorp, "A Study of Light Signals in Aviation and Navigation," Physics 1,273 (1931).280

Blondel, A.

A. Blondel and J. Rey, Comptes rendus 153, 54 (1911);162, 587 and 861 (1916); 178, 276 and 1245 (1924).

Green, H. N.

A. K. Toulmin-Smith and H. N. Green, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 26, 304 (1933).

Hampton, W. M.

W. M. Hampton, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 27, 46 (1934).

Langmuir, I.

I. Langmuir and W. F. Westendorp, "A Study of Light Signals in Aviation and Navigation," Physics 1,273 (1931).280

Pieéron, H.

H. Pieéron, Comptes rendus 170, 525 and 1203 (1920);178, 276, 966 and 1245 (1924).

Rey, J.

A. Blondel and J. Rey, Comptes rendus 153, 54 (1911);162, 587 and 861 (1916); 178, 276 and 1245 (1924).

Toulmin-Smith, A. K.

A. K. Toulmin-Smith and H. N. Green, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 26, 304 (1933).

Van Braam Van Vloten, P.

P. Van Braam Van Vloten, L'Éclairage des Routes Aériennes, Ve Congrés Internationale de la Navigation Aérienne (1930), p. 5.

Westendorp, W. F.

I. Langmuir and W. F. Westendorp, "A Study of Light Signals in Aviation and Navigation," Physics 1,273 (1931).280

Illum. Eng. (2)

A. K. Toulmin-Smith and H. N. Green, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 26, 304 (1933).

W. M. Hampton, "The Fixed Light Equivalent of Flashing Lights," Illum. Eng. 27, 46 (1934).

Physics (1)

I. Langmuir and W. F. Westendorp, "A Study of Light Signals in Aviation and Navigation," Physics 1,273 (1931).280

Other (7)

For Ec, near the threshold level, Toulmin-Smith and Green obtained k = 0.2 second. Therefore, a flash-duration of about 4 seconds would be required to give an apparentintensity ratio of 95 percent under these conditions.

P. Van Braam Van Vloten, L'Éclairage des Routes Aériennes, Ve Congrés Internationale de la Navigation Aérienne (1930), p. 5.

An investigation carried out for the Bureau of Air Commerce, of the U. S. Department of Commerce, by the National Bureau of Standards and described in detail in a report being issued by the Safety and Planning Division,Bureau of Air Commerce. Publication of this paper approved by the Director of the Bureau of Air Commerce.

Publication approved by the Director of the National Bureau of Standards of the U. S. Department of Commerce.

The word visibility, as used in this paper, refers to the capacity of a light source to stand out from the background,i.e., the contrast between the light source and the background. Other words which have this connotation are discernability, visiopia, and vis-ability. Visibility is chosen because it is the more common synonym and hence less likely to confuse the reader.

A. Blondel and J. Rey, Comptes rendus 153, 54 (1911);162, 587 and 861 (1916); 178, 276 and 1245 (1924).

H. Pieéron, Comptes rendus 170, 525 and 1203 (1920);178, 276, 966 and 1245 (1924).

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