A skyrocket is a type of firework that uses a solid-fuel rocket to rise quickly into the sky; a bottle rocket is a small skyrocket. At the apex of its ascent, it is usual for a variety of effects (stars, bangs, crackles, etc.) to be emitted. Sky rockets use various stabilisation techniques to ensure the flight follows a predictable course, often a long stick attached to the side of the motor, but also including spin-stabilisation or fins.
These rockets have been made at least since the early decades of the 20th century, and in many countries, including Japan, China, and Macao. The older type of bottle rocket was typically a black powder skyrocket with an engine about 2 inches (5 cm) long and up to 0.375 inch (9 mm) diameter, mounted on a thin bamboo splint and often having a small report charge. Modern bottle rockets are small and very cheap. They are often sold by the box (but more commonly by the pack, or by the gross, a packet of 144 rockets) for less than $US 0.20 each.
A bottle rocket consists of three major parts including:
- The rocket engine. This will typically use a black powder-type fuel, possibly with additives to produce a decorative spark trail as the rocket ascends, but they have also used other chemical reactions for thrust. The fuel is pressed to form a solid grain inside a cardboard Lub tube; this tube is sealed at the top, but open at the bottom with an air gap. When the fuel is ignited from the bottom, hot gases expand in the air gap giving it an upward motion. The expanding air is then expelled downwards, propelling the rocket upwards. Other fuels are possible. A common alternative choice is whistle mix, to produce a whistling rocket.
- The nose cone. In addition to serving its aerodynamic role, the nose cone typically contains the rocket's payload. This may include exploding fireworks, colored stars, a parachute, confetti, or other decorative items.
- The guide stick. A typical bottle rocket, with no fins or other stabilizers, relies entirely on its stick for stability in flight. The stick's length and weight are chosen to achieve this.
A common misconception about professional fireworks displays is that skyrockets are used to propel the pyrotechnic effects into the air. In reality, skyrockets are more widely used as a consumer item. Professional fireworks displays utilize mortars to fire aerial shells into the air, not rockets.
Sale and regulation
Bottle rockets are specifically illegal in many jurisdictions, even those where most other consumer fireworks are legal. They are sometimes considered to present a unique hazard, due to their ability to fly in many directions other than vertically.
In India, bottle rockets are set off during the Hindu festival of Diwali, and are sold in the millions.
In the Philippines, Republic Act 7183 was enacted to regulate and to control the sale, distribution, manufacture and use of fireworks and firecrackers for public safety. According to the said law, skyrockets (known in the Philippines as kwitis) are legal and are designed to propel from 40–50 feet (12–15 m) before exploding. Despite being legal, it poses danger to those using it. In 2012, it was recorded that skyrockets were the second most harmful firecracker after piccolo.
In Thailand's Isan region, many are made by hand and sold in conjunction with Rocket Festivals. The largest bottle rockets used at the festivals are Bang Fai rockets which can be up to 20 metres long and charged with up to 500 kg of black powder.
In the United Kingdom firework rockets are sold by weight, e.g.: 4 oz (110 g), 8 oz (230 g), 1 lb. This is not the weight of the rocket itself, but rather of a lead sphere whose diameter matches that of the rocket motor, officially defined as "The weight of a lead sphere that is just supported by a tube that the rocket motor will just fit into."
Bottle rockets are illegal in several federated states in the United States, but are cheap and very easy to obtain there.
- Water rocket, a model rocket propelled by water and compressed air, sometimes referred to as a "bottle rocket" as they are often constructed from soda bottles.
- Authorization Guidelines for Consumer and Display Fireworks Archived 2011-04-01 at the Wayback Machine.
- "REPUBLIC ACT NO. 7183". chanrobles.com. Retrieved December 29, 2016.
- Roxas, Joseph Tristan (November 29, 2016). "PNP bares list of legal firecrackers, pyrotechnics for holiday revelry". GMA News. Retrieved December 28, 2016.
- Elona, Jamie Marie (December 31, 2012). "Piccolo, kwitis, Goodbye Bading, others lead 'cracker-related injuries". Philippine Daily Inquirer. Retrieved December 29, 2016.
- Wilhelm Klein; John Gottberg; Hans Hoefer (1987). Burma. APA Productions.
- Joshua Eliot; Jane Bickersteth (2003). Thailand Handbook. Footprint Handbooks. ISBN 1903471540.