Model Rocket Altitude Predictor
Experimental
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See also the multi-stage version or the user's motor version.
ALL NEW MOTOR THRUST PROFILESas of 26 April, 2004Updated again with new Ellis Mountain motors and Revisied Loki Data on 13 December, 2004 Kevin Carder of Teeniemünde now maintains the motor database. I know for a fact that this file contains some errors but it is a lot more up-to-date than what I had before. Pay particular attention to the total impulse reported for the motors you use and suspect bad profile data if the impulse is significantly different from the manufacturer's specs. Minor deviations are normal. You can still use the old profile set from http://webalt.markworld.com/webalt1.html or http://webalt.markworld.com/multistage1.html. The User's Motor version has not changed with this upgrade.
Please don't link directly
to this page. It moves around when things like this recent upgrade
occur. |
This page drives a rocket simulation program which will project the peak altitude and other flight profile information about a model rocket. First read the disclaimer. Next fill in the requested information about your rocket and select a motor. Then click the LAUNCH button to run the simulation and receive the results.
This simulation uses a number of approximations to simplify the amount of data you have to input. For instance, there is no attempt to simulate the effects of winds and the drag of your rocket is calculated with a simplified transonic drag model.
The default Cd of .75 should be pretty close for a typical, rocket-shaped, model vehicle with three or four average sized, airfoil fins a good smooth finish and a typical launch lug. For other vehicle geometries, you may need to supply a different Cd. See John S. DeMar's excellent Model Rocket Drag Analysis for more information.
The program interpolates (linearly)
between time/thrust data points in a motor-specific thrust profile.
If you would like to see a motor added,
Email 
the thrust profile
as a set of time (in seconds) and thrust (in Newtons) data points in
this format or try the
user-entered thrust profile version of this
program.
People often ask me the "formula" used by this calculator. Well, the best answer is F=MA. This calculator uses numerical integration which is how lazy programmers with fast computers do calculus. If you want to see how a real man does it, check Randy Culp's Analytical Solution!
Claimer:
Because of the approximations used, the large number of uncontrolled
real-world variables influencing rocket trajectory, and the very high
probability
that there are bugs in this experimental program, I cannot accept any
liability for the
failure of your actual rocket flight to conform to this projection.
I hope you enjoy the program and let me know how its projections
match any actual flight measurements you may make.
with
comments, corrections, and bug reports.
Visit the Mark Sullivan
home page for more technical hobby resources
or the Teeniemünde Rocketry Club