Whistles, pyrotechnic

Whistles, Pyrotechnic. US projectile ground-burst and booby-trap flash simulators precede their flash and expin with a whistling sound. The fact that certain compns whistle when compressed into a tube and ignited has been used in the fireworks industry for many years. The active substance most often used in pyrot whistles is gallic acid (3,4,5-trihydroxybenzoic acid). The K salts of benzoic acid of 2,4-dinitrophenol and of picric acid (2,4,6-trinitrophenol) and the Na salt of salicylic acid (o-hydroxybenzoic acid) are also effective. They are combined with K chlorate,... 

K picrate was used as early as 1869 in expls, such as poudres Designolles (K picrate + K nitrate + charcoal) and poudres Fontaine (K picrate + K chlorate). It has also been used in pyrotechnic whistle compns (Ref 8), proplnts such as Ballistite, and in some primer mixts, ie, K picrate, Pb picrate K chiorate (Ref 4)... 

Ellem (Ref 138, p 181) also describes pyrotechnic means of producing explosive and whistling sound. Recent advances in the art of generating oscillating light signals are described in Section 8 of this article... 

Occasionally new pyrotechnic phenomena are discovered (Refs 98,99 124) which may see application in special situations. An example is the devlopment of pulsating burning pyrotechnics which constitute the optical analogue to the familiar whistling compds (Ref 138, Formulas 156—60). Whereas pyrotechnic whistles have a frequency of 2000 to 5000 cps, the new compns bum in the range of 0.1 to 700 cps and are therefore well suited for acquisition by electro-optical devices... 

The active ingredients in pyrotechnic whistle compositions are invariably based on aromatic compounds such as gallic acid (10.1) or the salts of aromatic acids including sodium salicylate (10.2) and potassium benzoate (10.3). 

S. Oztap, The Pyrotechnic Whistle and Its Applications IF, Pyro-technica, XIII pp. 19-21, 1990. 

Two basic audible effects are produced by explosive and pyrotechnic devices a loud explosive noise (called a "report" or "salute" in the fireworks industry) and a whistling sound. 

Pyrotechnic compositions can produce two types of noise a loud explosive bang or a whistle. The explosive bang is achieved by placing a... 

Certain pyrotechnic compositions when compressed and burnt in an open-ended tube will whistle. These compositions usually contain aromatic acids or their derivatives, potassium derivatives of benzoic acid... 

Refs 1) W.R. Maxwell, Pyrotechnic Whistles , 4th Combstn Symp, Paper No 111, The Williams Wilkins Co, Baltimore (1953), 906 2) H. 

Pyrotechnic whistle Pyrovatex CP Pyroxene Pyroxenes Pyroxofop [105512-06-9] Pyroxylin [9004-70-0] 3-Pyrozolone [137-45-1" Pyrrhodte... 

With the possible exception of delay fuses, any pyrotechnic mixture represents a hazard worthy of report. Although the cause of frequent accidents reviewed in [2], compositions intended to explode or deflagrate are generally outside the field of this work and few are listed. Numerous reviews and specialist texts exist and hundreds of patents appear yearly. The account [1] of the theory and practice of pyrotechnics contains much useful information on the performance and potential hazards of a great variety of oxidant—fuel combinations which bum very rapidly or explosively. Safety measures are found in [2]. Other reviews written from a functional viewpoint are found in [3] and [4]. Some hazardously incompatible pyrotechnic mixes are reported [5]. Detonability of pyrotechnic compositions has been studied. Whistles and chlorate or perchlorate aluminium containing noise compositions often show detonability. Most others do not [6]. 

The pyrotechnic whistle ( whistling chaser ) is a device which, when ignited, emits a piercing whistle which continuously drops in pitch until the device bums out. 

The pyrotechnic whistle is coi osed of three basic parts a cardboard tube, a whistle powder charge, and an acoustical resonant cavity ( an estpty cylinder cal space) in front of the whistling charge in the direction of the fuse. Typical cavity dimensions are 5/16 inches in diameter and one inch deep. 

The empty space in the front of the tube forms a cavity which is resonant at the whistle frequency. The whistle mixture is a composition which has a burning rate that is much more sensitive to exhsust gas pressure than ordinary pyrotechnic mixtures. 

Although most pyrotechnic items produce some sound, for whistles and salutes sound is the primary effect. 

The whistling sound produced by blowing over the open end of a pop bottle is a good model to introduce the mechanism of pyrotechnic whistles. 

When a pyrotechnic composition, whose burn rate is quite pressure sensitive, burns in a tube, a whistling sound can be produced through a mechanism similar to a pop bottle whistle. 

Pyrotechnic whistle compositions seem to burn to produce an intrinsic coilection of high frequency sounds. These frequencies are characteristic of the formulation used. 

R. Amons, Consideration of Alternate Whistle Fuels , Journal of Pyrotechnics, No. 6, 1997. 

J. Domanico, G.V. Tracy, M.N. Gerber, Frequency Components of Pyrotechnic Whistles , Proceedings of the International Symposium on Fireworks, 1994. 

W.R. Maxwell, Pyrotechnic Whistles", Symposium on Combustion, 1952. Reprinted in Journal of Pyrotechnics, No. 4, 1996. 

M, Podicsak and M. A, Wilson, Study of Combustion Behaviour of Pyrotechnic Whistle Devices (Acoustic and Chemical Factors , Chap. 16 Pyrotechnic Chemistry, Journal of Pyrotechnics, 2004. 

In World War II, the Germans used picrate whistles as a psychological adjunct to bombs and they also used pyrotechnic whistles as gas alarms. In this country, the M] 19 Whistling Booby Trap Simulator, ignited by a pull cord, produces a shrill whistling sound for 31/2 sec from a 2-in. column of Formula 156. The A/I17 Booby Trap Fksh Simulator, pull-cord ignited, starts with a whistling sound followed by an explosive flash. 

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