Half Cat Rocketry

100 years ago today, Robert Goddard made the very first launch of a liquid bipropellant rocket.

Serial numbers are assigned in the order that form submissions were received, so don't hold off if you've got one built. The liquid motor is the important part, so it's fine if you only made the propulsion system. (screenshots of CAD unfortunately don't count 🙂)

If you've built a Mojave Sphinx, please let us know through our form! We use serial numbers to keep track of how many are out there - it's a critical metric to demonstrating the accessibility of amateur liquid rockets. forms.gle/BfUCZJpBVnmKtm…

@ShawnBRocketry It's a B33 Sphinx, which has a longer, thin-wall tank (.065" x 4') and lighter weight parts.

@HalfCatRocketry Great job! Besides the new pintle injector, is this a standard Mojave Sphinx build?

8,640' apogee, burn was cut short because the pintle tip evidently burst and dumped out the remaining oxidizer

SN 12's launch yesterday

Sphinx SN 23 Kitty Hawk (not ours) is out here too, going for it's first launch!

Good launch and descent! Heading out to recover

@TurbulentSphere Just a dash of hopium

@HalfCatRocketry Good luck! Any fuel additives in this one?

Back out at FAR on a calm Sunday morning, going for a launch of SN 12 Shiro Sphinx on our experimental pintle injector with ablative thrust chamber - hoping to set a new Mojave Sphinx altitude record.

Two good tests on Bobtail so far today, and currently recycling for a third. The new ox-centered pintle injector is working relatively well

Last month, @TurbulentSphere gave an excellent talk about the basics of amateur liquid rocketry. Give it a watch here: youtu.be/Fi6vmynh4rM?fe…

@realjamesnotley That's part of the motor. It's both thrust structure and an adapter to a 75mm motor mount.

@HalfCatRocketry Is the outer skeleton just for the test rig or part of the final airframe? Looks awesome

This Saturday, we conducted three more tests of Bobtail, our in-development all-COTS liquid rocket. We found problems and solved problems, evolving the design toward better usability and performance.

It's Half Cat Day, marking five years since we conducted our first test of a liquid rocket motor! Here's the longer message we posted to our discord server - so much has happened since then, and we couldn't have done it without the excitement and interest from everyone out there.

Photos from the four tests we did yesterday

Four tests completed us today, concluding with a Garfield Gorange E85 firing by Shiro Sphinx! That puts us at 100 firings, 12/15/2020 to 11/29/2025.

A few weeks ago we did three Mojave Sphinx launches, which put us at 96 total liquid rocket firings since our first test. Tomorrow we'll round that out to 100 in under five years, including the debut of our newest design, Bobtail (pictured on the test stand)

Composite photo of all three Mojave Sphinx launches taking off yesterday. Colorado School of Mines, UCSB Gaucho Rocket Project, and our own.

SN 17 taking flight