EVBEC

EVBEC stands for "Energy & Volume Based Estimator for Combustions", and is intended to calculate the muzzle velocity of combustion launchers. The latest version (V 1.3) can be downloaded from spudfiles right here

Physics model

EVBEC assumes that:

• Energy produced from combustion is directly proportional to chamber volume.
• The portion of this energy utilized in a launcher is directly derivable from the Chamber to barrel ratio.
• The latke tests are accurate.

From these assumptions, one can get the driving equation of EVBEC: v_simulation=v_test/SQRT((S_test/S_simulation)/(M_test/M_simulation))

Where:

• v is velocity
• S is chamber volume
• M is mass

Using this, the velocities are calculated for all the ratios tested by latke, and the proper ratio to use to find the velocity is indicated on a graph.

limits of the physics model

The physics model does not account for the following:

• Differing burn times
• Variations in efficiency caused by different projectile masses. (which is why the 1.5" data is "out there")
• Odd effects caused by launcher design (ie; breach restrictions).

Several of these problems are likely to be alleived when the results of some recent tests being carried out by pimpmann22 of the spudfiles forums are released.

use

Generic directions for use are provided in the documentation of the program, and a detailed artical on modeling combustion spudguns, mostly with EVBEC, is provided here.