The Project P rocket was built to measure motor pressure in flight! The picture on the right shows the launch of Project P.
We modified the the end closure of an Aerotech J350W to accommodate a pressure transducer. A small circuit board with amplification electronics was attached to the expansion port of R-DAS. A pressure range of 0 to 1000 Psi (0-68 Bar) was selected.
The figure below shows the measured motor pressure during flight. (click to enlarge)
Unfortunately the motor pressure was above the expected 1000 Psi, resulting in a signal overload!! However, we proved the principle. Next time we'll use a smaller amplification factor, so the pressure will be in the measurement range.
Click here to download the R-DAS file of Project P: projectp.zip (54277 bytes) (to be read with the R-DAS User Interface program). The pressure transducer was attached to the ADC0 input. ADC1 is a reference voltage signal to check the electronics. Note the point where the rocket separates and the pressure transducer cable is no longer attached to the pressure transducer and the signal becomes noisy.
Aerotech J350W with modified end closure showing pressure transducer, connector and cable to R-DAS.