PVC Hybrid Rocket Engine

Results--

The test was performed on 03/19/03 at around 10:30 am on a perfect spring day ( though it still wasn't spring). In general terms the test was very successful. Here are some field notes:

Clean spontaneous ignition
Burned less than expected
Nozzle failure
Chamber performed well, cool to the touch
Test stand worked as expected
Hydraulic load cell as expected
Video registry good

The video was digitalized and analyzed frame by frame to gather the data. The results can be seen here:

pvchybrid.xls

This next image is from such a document:

Illustration 21

Total Impulse = 654 NS
Class J engine

Nozzle failure clearly seen here

Illustration 22

Illustration 23

Chamber performed well.
The image below shows the chamber split in two at he middle with the fuel grain hardly burned. The idea of exaggerating the grain thickness was to protect the casing from over heating, this of course at a cost in mass fraction. Hybrids use an oxidizer to fuel ratio of 7:1, if the tank has a capacity of 440 grams then the fuel should have been around 63 grams. On this engine the actual grain was close to 450 grams. On a flying engine the fuel mass will need to come down.

The only reusable part on this engine is the injector.

Illustration 24

Illustration 25

After thoughts:

When comparing the actual burn time (approximated 2.6 sec) to the 4.5 sec seen on the operation tank test video I wonder if on the test stand the oxidizer tank was filled to capacity. This would explain the difference. Next time I will have to pay better attention to the NOX filling process.

The nozzle can definitely be improved, I am currently working on some ideas for future test.

Overall I think that the PVC engine is viable and can still be improved significantly.

Static Test 2 (April 18, 2003)

Static Test 3 (June 13, 2003)

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