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
four forces in flight;
thrust, and the
lift and drag.
There are many different types of model rockets. The first and
simplest type of rocket that
a student encounters is the compressed air, or stomp rocket.
The air rocket system consists of two main parts, the launcher and the rocket.
On the figure we show a generic launcher, although launchers come in a
wide variety of shapes and sizes. The launcher has a base to support
the rocket during launch. A hollow launch tube is mounted perpendicular
to the base and is inserted into the base of the rocket
before launch. The launch tube is connected to an air pump by
a hollow feeder line. The pump is used to pressurize the inside of the
body tube to provide
for the rocket. We have attached a pressure gage to the feeder line to
display the change in pressure in the system.
For many air rockets, the pump is simply a cylinder which can be collapsed
by striking with your hand or foot, which is where the "stomp" rocket got its
name. In our simulation, we are going to pump up the system, and then launch the
rocket, to better control and explain how the system works.
The other part of the compressed air rocket system is the rocket itself. The rocket has a
hollow body tube which is opened on one end and closed at the other end by the
nose cone. The body tube is only slightly larger than the launch tube. When
the rocket is placed on the launch tube, the body tube becomes a closed pressure vessel.
The pressure inside the body tube equals the pressure produced by the air pump.
Fins are attached to the bottom of the body tube to provide
during the flight.
of a compressed air rocket is similar to the flight of a
ballistic shell or a bullet fired from a gun.
full scale rocket
for which the
is applied to the rocket for a large portion of the flight,
the thrust of a stomp rocket is completely expended in the first instance of flight.
During the entire flight, only the
act on the rocket.
of a compressed air rocket proceeds in three stages; the pressurization of the body tube,
the initial acceleration along the launch tube, and the expulsion of the compressed
air from the rear of the rocket.
Here is a computer animation of the launch of a compressed air rocket:
You can launch the compresed air rocket by using the buttons at the
bottom of the simulator. "Start" brings the rocket back to its
You can download your own copy of this simulator for use off line. The program
is provided as Stomp.zip. You must save this file on your hard drive
and "Extract" the necessary files from Stomp.zip. Click on "Stomp.html"
to launch your browser and load the program.