Full Cat at Full Power. Successful Nitrous Bipropellant Static Test (Half Cat Rocketry)

June 16, 2023
Less than a month after it's first, fiery, static test attempt, Half Cat Rocketry returns to the iconic large vertical static test stand at FAR. (make sure you check out that test below if you haven't already)
• The Fiery Debut of the...
The ~800 lbf thrust rocket is packed with an "O" impulse of ethanol and autogenous nitrous oxide, and is designed to fly to at least 50,000ft on paper.
www.halfcatrocketry.com/fullcat
Static tests are important to characterize thrust data while considering losses intrinsic to hot firing. A hard or late start, unbalanced O/F mixtures at burnout, and propellant tank drainage efficiency, which can be as much as 80% depending on tank design, can all reduce the actual impulse.
In this static test, the rocket fired for 10 seconds, but was preceded by 2 seconds of cold flow. Cold flows dump propellant at a higher rate than when hot, due to the larger pressure differential between the injector and the chamber. With a design burn time of 14.4 seconds, the 2 seconds of cold flow prior is not very desirable, but not necessarily a barrier to launch. It's important however that this cold flow does not produce too much thrust as to start lifting the rocket before it can do so at a fast enough rate to achieve stability, or if it does, that the cold flow does not last for too long that the rocket can simply tip over off the end of the rail. One remedy for this is to use shear bolts as a hold-down, something that the Half Cat folks have experience with as L3 certified rocketeers.
The fuel line bursting from last time seems to be resolved with the switch from compression to Push-to-Connect, but the nylon tubing itself will still need to resist the pressure of the warming nitrous oxide, since the vapor pressure of the oxidizer increases with temperature.
This will all be important, as Full Cat is preparing to fly soon, and the full heat of the summer has yet to bear down on this tiny square in the middle of the desert.
It's also the first time I have utilized a drone to film a rocket, having set up and practiced it earlier that day. Though the drone I used can only film up to 1080p, as I'm transitioning to a 4K standard, it may prove to be a dangerous new addition to my already substantial camera lineup, for both my wallet and my workload.

[@user-qo4hc6jf1l]

I m getting a feeling that it’s need injectors to mix it’s a blast 👍

[@user-qo4hc6jf1l]

Is that oxygen and mixed later no2 what I see is it’s not burning constantly it’s not mixed properly why flame is going on n off 2 tanks Same pressure change the amount to
See ❤