Welcome to More Strib's Rocket Stuff
Is your model rocket stable? Will it fly straight? You need to know how the "Center of Pressure" relates to the "Center of Gravity". There are several programs available to calculate the stability of a rocket. The following technical reports explain the details behind rocket stability, and give the formulas required to calculate the stability by hand.
The out of print Centuri Technical Information Report TIR-30 is now available at JimZ Rocket Plans (TIR-30)
NOTE: a PDF version is available there too and it is 1.3 MB!
Calculating the Center of Pressure of a Rocket
The out of print Centuri Technical Information Report TIR-33 is available at JimZ Rocket Plans (TIR-33)
NOTE: a PDF version is available there too and it is 5.7 MB!
- Elliptical Fin CP Calculations", an article by James Barrowman in the Nov 1970 issue of Model Rocketry
- "Supersonic Rocket CP Calculations", an article in the February 1973 Model Rocketeer discussing the behavior of the center of pressure of a rocket flying past Mach 1.
- "Wind Stability-What Barrowman Left Out", a paper by Robert Galejs (a PDF file)
RockSim Rocket Design Program is available from Apogee Rockets
This software will calculate the stability of a rocket design and perform altitude prediction of the design.
This software will calculate the stability of a rocket design.
There is also OpenRocket an Open Source model rocket simulator that has a lot of features. There is an interesting presentation comparing OR to Rocksim, VCP and wRASP at the Fox Valley website look under "NARCON 2010"
Model Rocket Altitude Prediction
The out of print Centuri Technical Information Report TIR-100 is in a medium-resolution pdf file.(4.7 MB)
The Estes Educator site has pdf files of several publications, including Altitude Prediction Charts, TR-10
CHeap And Dirty ALTITUDE CHART Program
This program uses the formulas from Centuri's old technical report on predicting a rocket's altitude (TIR-100) to generate altitude and coast time charts. It will either calculate the maximum altitude and coast time for a given rocket, or generate tables for various drag form factors and weights. This output is in the form of delimited text file that can be imported into a spreadsheet to produce graphs.
The current version uses ounces for weight, inches for length, and feet for altitude. It is not anywhere as sophisticated as Rocksim from Apogee Rockets, or wRASP. It is a CHAD (CHeap And Dirty) way to plot off some altitude charts for casual use. Then again, the plot of altitude vs. liftoff weight does illustrate the concept of optimum mass!
Click here to download RockAlt. It is a zip file with a "setup.exe" included . VB will have to install a few files to make the windows run OK. I have run the program on XP, Windows 98, and Windows NT 4.0.
NOTE: Version 1.3 is now available! I have added a "File open" dialog to allow flexibility in saving the output file. The zip file (rockalt13.zip) is approx 1.89MB.
More Centuri Technical Reports (at Buzz Nau's site)
A good friend from church wrote his personal story about the D-Day invasion. I put his story on the web for others to read because I think it is important we preserve the stories from "The Greatest Generation". Click here to read it. He wrote another story about the work of the 155th Photo Recon group. You can read it here.