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Whirly tube

The whirly tube, corrugaphone, or bloogle resonator, also sold as Free-Ka in the 1960s-1970s, is an experimental musical instrument which consists of a corrugated (ribbed) plastic tube or hose, open at both ends and possibly wider at one end (bell), the thinner of which is rotated in a circle to play. It may be a few feet long and about a few inches wide. The faster the toy is swung, the higher the pitch of the note it produces, and it produces discrete notes roughly belonging to the harmonic series, like a valveless brass instrument generates different modes of vibration. However, the first and the second modes, corresponding to the fundamental and the second harmonics, are reported as being difficult to excite. To be played in concert the length of the tube must be trimmed to tune it.

Sound
Hopkin describes a single whirled corrugaphone as capable of producing three or four different pitches. Crawford describes harmonics two through seven as reachable while whirling, though seven takes, "great effort." Hopkin describes that with a corrugahorn, "with tubes of suitable length and diameters, the range extends well up the [harmonic] series, where the available tones are close together and you can, with practice, play quite melodically." In fact, since each sounding mode plays throughout a range of speeds (rather than at one specific speed), it is difficult to skip over harmonics, as this requires a jump in speed (rather than gradual change), though this is easily done using one's tongue and throat to interrupt the air flow with a corrugahorn. dissonant adjacent harmonics may sound simultaneously, such as 15 and 16. The modes of a corrugated tube are usually lower than those of an uncorrugated tube of the same length and diameter, and, "audible vibration in the whirly tube appears only when air flow velocity exceeds a certain minimum, which may preclude the sounding of the fundamental or lower harmonics." The timbre of the notes produced by the whirly tube are, "almost all fundamental," according to Fourier analysis (similar to sine waves). On the contrary, the present theory of sound production in corrugated pipes refutes the assumptions by Crawford (1973). : \text{frequency} = \frac{\text{bumps}}{\text{sec}} = \frac{\text{bumps}}{\text{inch}} \times \left(\text{air flow velocity in } \frac{\text{inches}}{\text{sec}}\right) The characteristic speed is the mean flow through the pipe U and the characteristic length must be a multiple of the spacing between corrugations, nL, where n is an integer number and L is the distance between corrugations. At low speeds, the unstable interior flow needs to travel several corrugations to establish the feedback loop. As the speed increases, the loop can be established with fewer corrugations. The Strouhal number :\mathrm{St} = \frac{f_n n L}{U} was used as the scaling factor. A unique aspect of this whistle is that the internal flow carries both the unstable vortex downstream and the returning feedback signal upstream. ==Use==
Use
A corrugated plastic tube whirling instrument became an instant, if short-lived, cultural phenomenon in late 1960s New York City under the name "Free-Ka", sold by street vendors, as captured by The New Yorker in 1970. It was used by Peter Brooks in the early 1970s in his production of Shakespeare's A Midsummer Night's Dream. It has been used by a number of artists including Peter Schickele, Frank Ticheli, Paul Simon, Macy Gray, Loch Lomond, and Yearbook Committee. Also in Brett Dean's Moments of Bliss (2004) and by The Cadets Drum and Bugle Corps in 2011. Donald Sosin's "137 Ridges" (1971) for flute, vibraphone and 15 tuned Free-kas was performed at the University of Michigan. It has been employed in some of Peter Schickele's comic P. D. Q. Bach compositions such as the Erotica Variations: IV (1979), Missa Hilarious (1975), and Shepherd on the Rocks with a Twist (1967). David Cope, in 1972, discussed a cugaphone, which, in 1997, he describes as an instrument built from a trumpet mouthpiece attached to a long piece of 3/8-inch bore plastic tubing with a kitchen funnel, usually in hand, at the other end acting as the bell; thus sound may be modulated by directing the funnel, applying pressure to the funnel, or by swinging the funnel around one's head and creating a Doppler effect. This version of the instrument would require brass embouchure technique rather than corrugation. By 1997 ensembles of cugaphones existed. The inventor is not known, though Bart Hopkin credits the late Frank Crawford of the UC Berkeley Department of Physics with, "developing the idea and researching the underlying acoustics," This requires a tube with a diameter smaller than commonly marketed as toys (a one inch diameter is too great, a half-inch is not), Hopkin recommends 3/8" gas heater hose as the most playable of widely available sizes. Crawford invented an "inverted-wastebasket water piston" operated version he called the "Water Pipe", with which he could easily reach the eleventh harmonic. ==See also==
Source: Wikipedia ↗
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