Flying model rockets is a relatively
and inexpensive way for students
to learn the basics of forces and the
of a vehicle to external forces.
a model rocket is subjected to
thrust, and the
lift and drag.
The relative magnitude and direction of the forces
determines the flight trajectory of the rocket.
On this page we show the events in the flight of a
compressed air rocket.
Air rockets are among the
simplest type of rocket that
a student encounters.
The rocket consists of a hollow tube, with a nose cone
on one end and
fins at the other end.
Prior to launch, a hollow launch tube is inserted into the
open end of the rocket. The launch tube is connected to an air
pump which pressurizes the inside of the rocket body tube.
the thrust produced by the air pump is greater than the weight of the
rocket and the net force accelerates the rocket away from the pad.
All of the thrust of an air rocket is expended as the rocket
leaves the launch tube.
During the flight, the weight of the rocket is constant
and there is no thrust since the air rocket has no engine.
The constant weight of an air rocket is very different from
full scale rockets
in which the vehicle weight changes as the propellant is expelled through
The lack of thrust is also different from
full scale rockets which provide thrust during the entire ascent.
And unlike full scale rockets, air rockets rely on aerodynamics for
stability. The launch tube
provides stability during launch since the low velocity makes the aerodynamic
Leaving the pad, the air rocket begins a
The flight of an air rocket is quite similar to the flight of a
ballistic shell, or a bullet fired from a gun,
except that aerodynamic drag
alters the flight of the air rocket.
The vehicle slows down under the action of the weight and drag
and eventually reaches some
maximum altitude which you can
using some simple length and angle measurements and
The rocket then begins to
to earth under the power of gravity.
Air rockets usually do not include a recovery system like
After recovering the rocket, you can fly again.
You can study the flight characteristics of an air rocket by
On the graphic, we show the flight path as a large arc through the sky.
Ideally, the flight path would be straight up and down; this provides the
largest maximum altitude. But air rockets often turn into
the wind during flight because of an effect called
weather cocking. The effect is the result
of aerodynamic forces on the rocket and cause the maximum altitude to be
than the optimum.
The parabolic arc trajectory also occurs if the launch platform is
tilted and the rocket is launched at an angle from the vertical.
Types of Rockets:
Compressed Air Rocket:
Paper Rocket: Grade 6-10
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