The Evolution of Nitrous Liquid Rockets (UCF)

July 15, 2023
Nitrous Bipropellant rockets have made a resurgence in recent years, thanks in no small part to Half Cat Rocketry. This small two-person operation started out at the University of Central Florida, and after graduating, they have continued their work with autogenous nitrous systems in California. Back at their alma mater, the Knights Experimental Rocketry group have collaborated with them to build their own competition liquid bipropellant rocket of a Half Cat pedigree, with which they sought the FAR DPF prize.
The KXR team's Valkyrie rocket is equivalent to an "M" motor in impulse, and the team have been careful to make the distinction that theirs is the first built by a registered student organization at their school. The original Half Cat rocket would have been the first winner of the FAR DPF prize when it first flew, if it had been officially registered as part of a university organization.
During the searing heat of midsummer, where you'd ought to factor in the density of bugs into your drag calcs, KXR was successful in flying their rocket to 4884ft AGL. This was only after dumping their propellant in their first attempt, in what seems to be tradition for new rockets. In succeeding to fly Valkyrie, the KXR team are able to finally claim the DPF prize for UCF with a nitrous bipropellant rocket. The prize requirements are due to change to LOX-only by the end of the year, making this achievement a timely one.
The original Half Cat team also joined them with a rocket of their own, as their own launching activities hasn't slowed down at all since graduating. While Full Cat waits for better weather, the smaller Mojave Sphinx made its debut flight, and all this in the background of the mighty Bavarian hybrid rocket preparing to fly on the same day, but that's for a future video...

[@fbwa32nxfan29]

Another great video! Thank you for showing the awesome work these teams have done!

[@matthiasm.7667]

Hey Derek I have a question: Blowdown rockets increase pressure and thrust over their firing, but by how much? I don't need a precise number (I know it depends on many factors), I just need an estimate.

[@eriksolberg4737]

In a blowdown rocket, the tank pressure decreases as the burn progresses. The reason for this is that there isn’t a pressurant keeping a constant pressure in the tank.

[@bbrockert]

I'm surprised T:W>1 in unlit mode.

[@eriksolberg4737]

It was lit it was just really hard to tell. There is about .5 seconds of what looks like “cold gas”. There’s another angle where you can see combustion inside the chamber during that period. It was really oxidizer rich during that period due to our ignitor.

[@andressarmiento2777]

​@@eriksolberg4737 Actually ☝️

[@eriksolberg4737]

@@andressarmiento2777bruh

[@alexanderpatrus9588]

If you are referring to half cat, that was crazy that it took off in a coldflow

[@eriksolberg4737]

I just realized you were probably talking about half cats first attempt 😂