A method for obtaining a power spectrum of gust vertical velocity over a wide range of wavelength from simultaneous measurements made in flight has been devised and applied. This method has the advantage of not involving the use of airplane transfer functions. A gust vertical velocity spectrum was determined for one meteorological condition for wavelengths from 10 feet to 60,000 feet. The test was conducted at low altitude in clear-air turbulence having a root-mean-square intensity of 5 feet per second. At the higher frequencies (shorter wavelengths),the power spectral density varied at a rate which was between the -5/3 power which has been predicted theoretically and the inverse square of the frequency. The spectrum which was obtained tended to flatten out for the longest test wavelengths. The break frequency which provides an indication of the scale of the turbulence occurred at a wavelength of approximately 6,000 feet. The results obtained indicate that the method of obtaining spectra used in this investigation is practicable.
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