Awesome Video of Interorbital Systems Flight Test at FAR

This upper-stage engine test was conducted on June 30 at the Friends of Amateur Rocketry (FAR) site northeast of Koehn Lake in the Mojave Desert. I was there. It was very cool to watch in person.

Engine Details

White Fuming Nitric Acid / Turpentine
Hypergolic Storable Propellants
Ablatively Cooled
750 lbs Thrust

  • Paul451

    Odd fuel choice for an upper-stage.

  • tp1024

    No more odd than the upper stage of the Electron rocket using ADN (or whatever the “green propellant” is). They obviously wanted to have a hypergolic fuel that has a small-ish chance of killing them on the ground by its mere presence in the air.

    Then again, there is something dubious about the whole company, but at least that partcular choice is reasonable – albeit on the side of rather poor performance.

  • passinglurker

    WFNA is relatively safe to handle as far as viable oxidizers go and both are cheap even when used in bulk. Which is important because considering how inefficient it all is you’ll need a lot of it.

    It’s basically a modern attempt at implementing OTRAG.

  • Paul451

    considering how inefficient it all is

    That’s what I found odd. I could understand using a 240s propellant if it was genuinely harmless/safe. But any of the nitric acids are un-fun to work with. If they aren’t inactivated, they’ll eat your tanks, if they are, you get to play with HF.

  • passinglurker

    It’s corrosive and hypergolic with many fuels but that’s it it’s only corrosive and hypergolic. You don’t need the full hazmat rig like NTO/MON, nor the cryo infrastructure of LOX, and it doesn’t pose the risk of self-degenerating like HTP, or NOX. It was a common choice early in the space age but was abandoned for lousy performance compared to the more hazardous options. Inefficiency is the largest issue but carbon tanks are a thing now so it might compensate. Therefore if I wanted to pick over issues with interorbital (and I do like any dubious micro sat launcher these days) it wouldn’t be the choice of propellants.