A balloon rocket is a rubber balloon filled with

air An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

or other gases. Besides being simple toys, balloon rockets are widely used as a teaching device to demonstrate basic physics.

How it works

To launch a simple

rocket A rocket (from , and so named for its shape) is a vehicle that uses jet propulsion to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely ...

, the untied opening of an inflated balloon is released. The elasticity of the balloon contracts the air out through the opening with sufficient force and the resulting pressure creates a

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

which propels the balloon forward as it deflates. It is usual for the balloon to be propelled somewhat uncontrollably (or fly in and unstable

centre of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the barycenter or balance point) is the unique point at any given time where the weighted relative position of the distributed mass sums to zero. For a ...

), as well as turbulence that occur in the opening as the air escapes, causing it to flap rapidly and disperses air outwards in random direction. Near the end of its deflation, the balloon may suddenly shoot quickly in the air shortly before it drops down, due to the rubber rapidly squeezing out the remaining air inside as it reaches the inclination to return to its uninflated size. The flight altitude only amounts to some meters, with larger or lighter balloons often achieving longer flights. In addition, a cylindrical-shaped (or "airship") balloon may have a more stable flight when released. If the balloon is inflated with

helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

or other

lighter than air A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result, making it useful in lifting lighter-than-air aircraft. Only certain lighter-than-air gases are suitable as lift ...

gases, it tends to fly in an inclined trajectory (usually going upwards), due to the light nature of the gas.

In physics

The balloon rocket can be used easily to demonstrate simple

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

, namely Newton’s third law of motion. A common experiment with a balloon rocket consists in adding other objects such as a string or fishing line, a

drinking straw A drinking straw is a List of eating utensils, utensil that uses suction to carry the contents of a beverage to one's mouth. A straw is used by placing one end in the mouth and the other in a beverage. By applying suction with the mouth, the air ...

and

adhesive tape Adhesive tape is one of many varieties of backing materials coated with an adhesive. Several types of adhesives can be used. Types Pressure-sensitive tape Pressure-sensitive tape, PSA tape, self-stick tape or sticky tape consists of a pre ...

to the balloon itself. The string is threaded through the straw and is attached at both ends to fixed objects. The straw is then taped to the side of the inflated balloon, with the mouth of the balloon touching the object it is pointed. When the balloon is released, it propels itself along the length of the string. Alternatively, a balloon rocket car can be built.Summer Science Newsletter: Building a balloon rocket car
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Rocket balloon

There is also a dedicated toy known as a rocket balloon, usually tubular-shaped and inflated with a special pump (pictured). These balloons, when released, propel in a more stable direction because of a steadier thrust of air and elongated shape, unlike ordinary round balloons, which often launch uncontrollably. Aside from the shape, rocket balloons are also characterized by their distinctive loud buzzing or screaming noises due to the tight, reed-like opening designed to make noise as the air rushes through. They are also known as noisemaker balloons, due to the aforementioned noise

As cartoon gags

The fact that an untied toy balloon flies away when released sometimes has become a staple recurring gag and comedic effect in most

cartoon A cartoon is a type of visual art that is typically drawn, frequently Animation, animated, in an realism (arts), unrealistic or semi-realistic style. The specific meaning has evolved, but the modern usage usually refers to either: an image or s ...

s. For instance, when an object or a character is comically being " inflated" and then deflates, it flies away uncontrollably, in a similar fashion to a balloon itself. In addition, the noises that a balloon creates when deflating is sometimes used in conjunction with this comedic effect.

References

External links

NasaQuest: Teacher Information on balloon rockets

Balloon Rocket Video
{{DEFAULTSORT:Balloon Rocket Balloons Inflatable manufactured goods