Strib's Rocket Page

I'll admit it. I am a rocket nut. I was glued to the TV set when Alan Shepard blasted into space on May 5, 1961 (I was just shy of 4 years old!) and have been hooked ever since.

I discovered model rocketry in 1968 along with my best friend Greg Smith in Lake Havasu City, Arizona, when the hobby shop opened. We flew Centuri and Estes rockets. About a year later, we moved to Tucson (I was still unpacking my room during the Apollo 11 moon mission).

Starting junior high, I quickly became involved with a rocket-building class led by our counselor, Mr. Craig. The class became a club, the Sunnyside Organization for the Advancement of Rocketry (SOAR), named after our school, Sunnyside Junior High. Mr. Craig led us into performing rocketry lectures and demonstrations for classes at our school, and others in Tucson. We hosted a couple of local rocket meets and competed with a couple of local clubs. The photo of the Mercury Redstone was taken at one of those launches.

Model Rocketry sparked my interest in engineering and math. Designing, building, and flying a rocket is a very satisfying activity. I haven't moved into "high power" rocketry, but would like to some day.

OGIVE NOSE CONES

I enjoy running computer simulations of rocket flights, and delving into the math behind them. I recently worked on a derivation of the formulas to generate ogive nose cones the link will show you how to draw tangent ogives and secant ogives. Kem Payza created an Excel spreadsheet that will draw nose cone profiles for ogive, elliptical, parabola, and other shapes. Click here to download the file (UPDATED: approx 472 KB zipped).

Virginia Tech has a web site on aerodynamics called Configuration Aerodynamics Course that has a lot of information, including a pdf file called Geometry for Aerodynamicists. This document contains formulas for other nose shapes, such as the Von Karmen ogive (79 KB).

Computational Fluid Dynamics (CFD)

For more information on CFD analysis, go to CFD Online

CHeap And Dirty ALTITUDE CHART

This is a Visual Basic program that 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. It will generate a chart for maximum altitude, and coast time for various liftoff weights and CDAs. The charts are not as elegant as a spreadsheet's, but they can be printed out.

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 Windows 98, Windows NT 4.0, and Windows XP.

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.

The Centuri report TIR-100 is available here. (If the web site says it is unavailable, wait an hour or so for the download limit to timeout.)

ALTITUDE TRACKING

Now that you have predicted how high your rocket can go, how do you find out how high it actually flies?

BARROWMAN CENTER OF PRESSURE CALCULATIONS

Here are scans of the old technical reports TIR30 and TIR33. (Note if the web site says it is unavailable, wait an hour or so for the download limit to timeout.)

Several computer programs are available to calculate the CP of a rocket to determine if it is stable VCP is a free program. Rocksim from Apogee Rockets has more features but of course you have to pay for it!