An 11 Foot Liquid-Fueled Rocket Flies High Over The Desert

Nov 05, 2026 Last reply: 2 days ago 3 Replies

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pfischer 5 days ago

The number that jumped out at me first was the acceleration: nine g's off the rail, with analysis putting thrust around 360 lb. For an 11 ft tall vehicle, that is a punchy ride, and it makes the liftoff easy to picture even from far away. A small liquid-fueled machine pulling that hard right at ignition is genuinely rare in hobby circles, and the maker pulled it off.

The vehicle itself is a neat piece of engineering. It burns an N20/IPA combination and runs a blow-down pressurization architecture, which keeps the fluid system simpler than a regulated setup would be. The name Darcy-1 is a nice touch too, a nod to the Darcy-Weisbach equation, which feels fitting for a project where pressure losses matter a great deal.

The flight happened on Saturday, Aug 6th, from the FAR site out in the Mojave desert, lifting off in the early afternoon along a tall vertical metal launch rail. Ignition came with a loud roar, and the vehicle climbed to at least 20,000 ft. That is a serious altitude for a first liquid-fueled attempt, and it speaks well of how the whole system held together under load.

The one open question is recovery. The vehicle flew high and was lost, so there is no hardware back for inspection or a second flight. That seems like the classic trade-off on a high-energy debut: push performance and accept the risk of never seeing the airframe again. I would still love to know what post-flight data survived, since the thrust and acceleration figures suggest the propulsion side worked exactly as intended.

Project by YJSP – Yellow Jacket Space Program. Watch it on their YouTube channel:

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MuleMesa 4 days ago

Going with a blow-down pressurization architecture looks like a smart call to me. It cuts out a lot of complexity in the pressure feed, and on a first liquid flight fewer valves and regulators means fewer failure points. The trade-off, as I understand blow-down systems, is that chamber pressure drifts down as the tanks empty, so you give up some steady performance for reliability. Given the nine g departure off the rail, the maker clearly got the sizing right anyway.

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WorksQuarry_1989 4 days ago

Curious about one thing: the 360 lb thrust figure is described as coming from analysis. Was that worked out from on-board flight data, or from a separate static fire before the launch? With the airframe lost, I am wondering how much instrumentation made it back, and whether the nine g acceleration reading came from the same analysis or from something measured directly on the rail.

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NomadAnvil_1973 4 days ago

For a follow-up flight, I would suggest adding some kind of independent tracking beacon on the recovery side, so a vehicle that flies this high has a better chance of being found even if it drifts far from the site. Losing an airframe after a clean 20,000 ft climb means losing all the flight hardware data with it. A simple locator that survives the landing could turn the next flight into a two-flight program instead of a one-shot debut.

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