Introduction

      This NAR Research & Development report describes a series of experiments 
using a computerized wind tunnel to determine the drag coefficients of typical 
model rocket designs.  The main goal of this report is to derive a practical 
list of drag coefficients to improve the usefulness of existing altitude 
prediction software. To verify the accuracy of the data, the predicted altitudes 
are compared to actual tracked altitudes for a sample of the models tested 
(TBD).

      The drag measurements were made using a commercially available wind tunnel 
intended for experimentation at the high school and undergraduate college level.  
The design of this equipment is less sophisticated than a wind tunnel found at a 
research facility, but is more accurate than the typical home-made device.  As 
shown in this report, the wind tunnel is tested for accuracy and is found to be 
sufficient for the purposes of this report.

      Several model rockets were built for each of six series of tests to 
isolate the major affects on drag:  frontal area, finish, nose shape, body 
shape, fin cross-section, and launch lug.  The resulting table of drag 
coefficients represents most of the typical configurations, making it very 
useful in many areas of model rocketry.  Some applications are:  optimizing 
parameters for maximum altitude in a competition design; selecting an 
appropriate motor for the model and field size; and verifying compliance within 
the limit of an FAA waiver.

     The methods used in this report may prove useful in studying other research 
topics in the future.  Some of these ideas are discussed further in the last 
section.