Bamboo cannon

A bamboo cannon (Malay: meriam buluh, Jawi: مريام بولوه ; Tagalog: kanyóng kawayan; Waray: lantaka: ) is a type of home-made firecracker which is popular during the Hari Raya festive season in Malaysia, and during New Year's Eve celebrations in the Philippines. Like other fireworks, bamboo cannons are illegal as stated in Malaysian Explosive Act 1957; ironically, more Malay children turn to the more dangerous bamboo cannon as an alternative to commercial firecrackers which were banned by the government.

Operation

A typical bamboo cannon consists of a large bamboo node or tube containing some water to which a little calcium carbide is added. The carbide reacts immediately with the water releasing acetylene gas, which has the widest range of explosive limit of any common chemical[1] and a very low ignition energy. A sharp report is produced when a flame is introduced into the bamboo chamber. However, the low density of the acetylene/air mixture is such that the total combustion energy is quite low and weak containers such as bamboo or even glass[2] rarely shatter. Adding too much carbide does not increase the energy of the explosion but instead weakens it due to high fuel to air ratio. After the shot, fresh air is needed in the tube in order to have another explosion after more carbide is added.

The operating principle also works with other combustable fuels besides acetylene, but since most others have narrower explosive limits, the effect is not as reliable. Common examples are solvent-containing aerosol consumer products such as spray paint or hairspray.

Less-volatile fuels can also work, with skill, such as 200ml of hot kerosene, poured into a small hole near the breech of the cannon. A lighting stick is used to ignite the fumes and fire the cannon, then fresh air is blown into the small hole and the cannon fired again. The bamboo used for this is usually around 4 to 6 inches in diameter and 4 to 5 feet long.

In the Philippine city of Kidapawan, North Cotabato, the Kanyóng Kawayan Festival is held from 14-20 December to promote safer noisemaking alternatives during the Christmas season. Empty powdered milk cans are common projectiles used in the city-wide contest held during the event.[3]

A variant form, known as bong-bong, is used by the people of Mangaldan, Pangasinan, but with water and motor oil as the fuel.

Variation

A Filipino derivative made from PVC piping or segmented joined tin cans is colloquially known as a boga. It is operated in much the same way as a bamboo cannon, but is held in the manner of a rocket launcher. Originating in the province of Cavite,[4] use of the device has been banned by the Philippine government since 2006.[5]

References

  1. ↑ see the explosive limit table
  2. ↑ see Big Bang Cannon, where demonstrations using glass cannons were done
  3. ↑ "KANYONG KAWAYAN FESTIVAL". Department of Tourism. Calendar of Festivities. 2009. Retrieved 26 February 2015.
  4. ↑ "Pinoys find another way to welcome the New Year". Manila Bulletin Online. 2005-12-31. Archived from the original on November 22, 2008. Retrieved 2008-12-29.
  5. ↑ ""Bawal ang Boga", DOH says this holiday season". Retrieved 2008-12-29.

See also

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