PR-V4 PDM3 - 09/11/2008

The main innovation of this test has been the use of a De Laval nozzle. Every other aspect(number of grains,inhibitions..) was kept identical to PDM2: the aim was to maintain a thrust curve similarl to PDM2.
The reason of the experiment's non-repeatability is to blame on unexpected factors such as burning chamber depressurization due to o-ring failure, and grain alteration caused by prolonged storage.
In the following test we will try to solve those issues.

Acquisition frequency [Hz]: 240
Propellant: P-1
Propellant Mass [g]: 261.8
Mean density [g/cm^3]: 1.846
Ideal density ratio: 97.8 %
Grain number: 3
Total grain length [mm]: 202
Port grain diameter [mm]: 8
Throat diameter [mm]: 8.5
Inhibition: External, final terminated (intergrain faces not inhibited).
Action time (ta) [s]: 1.242
Burn time (tb)[s]: 1.130
Maximum thrust [N]: 502.4
Mean thrust (tb)[N]: 213.3
Mean pressure (tb)[bar]: 27.6
Total impulse [Ns]: 305
Specific impulse [s]: 119.4

Environmental data:
Atmospheric pressure [mbar]: 1031
Air temperature [°C]: 12