Tender Descenders: 0.2 grams of FFFF Black Powder
Piston: 0.176 grams of FFFF Black Powder
Some black powder spilled out a little bit while manufacturing the Firebolt Jumbo, so I tried to compensate by eye (maybe adding a little extra?)
Note: that the final rod seal is kind of messed up and cut up. It still seemed to seal though by doing a tug test with the inlet port closed up.
One thing to note about this test was that it was the most energetic test performed to-date. This could be because of several reasons:
- Different quantity, type, and application of lubrication from previous tests
- Different piston than had previously been fired at all
- More vent holes in the mission package
- One theory as to why the Ground Tests performed on Pathfinder were less effective was because the mission package didn't have vent holes and the diaphragm was previously solid. This would have led to a vacuum occurring in between the cup and the diaphragm, slowing it's movement
- Better contact between the cup and the booster section (the COTS coupler was quite thick, likely thicker than the SRAD Pathfinder coupler
- the ground test didn't include the motor case, fin can, payload, ballast, or nose cone. Adding these would have resulted in a lower separation velocity.
1 Comment
Unknown User (astrocrg@mit.edu)
I'd evaluate the 'cup-coupler' contact theory as non-credible, unless you're suggesting a structural failure of the booster-mission package coupler, which I think can be ruled out by the post test condition of the Pathfinder coupler.
I'd put serious stock in the vent hole theory, there is a 18.47 difference in area between the piston and the diaphragm-bulkhead volume. I'd bet that the difference in mass was also a significant contributing factor, though Pathfinder's wet mass was considerably lower than Hermes 1's dry mass.
I'd be interested in how the extension velocity of a piston changes with the number of cycles on it.