Video of Virgin Orbit Engine Test

Video Caption: We are always excited to test our most powerful engine, the NewtonThree, for long duration. During this specific test, we completed a full ‘mission duty cycle’–a fancy way of saying that we fired the engine for as long as it would fire on a full flight to orbit. We also gimbaled the engine, meaning we changed the angle of thrust by several degrees during the course of the firing. The ability to gimbal is important, since that is one of the main ways a rocket ‘steers’ on its way to space!

As a reminder: our LauncherOne rocket has two rocket engines on board: a single NewtonThree on the main stage and a single NewtonFour on the upper stage. You can see a full duration NewtonFour firing here: https://youtu.be/AGZF4o-gwHk

  • passinglurker

    So does the newton family have a gimmick or is it just a vanilla “playing it safe” “no new innovations here” kerolox gas generator?

  • Does that plume look a little ratty to anyone else? Makes me think combustion isn’t fully stable.

  • Lee

    Yeah, both the plumes for the N3 and the N4 look ratty to me. Especially right behind the nozzle. Looks unstable.

  • Andrew Tubbiolo

    I was thinking the same thing. Could it be that they’re throttling film cooling and the unburned fuel is making the exhaust look more variable? The film cooling ‘coke’ looks somewhat variable right at the exhaust. Of course that could be from thrust pulsations due to instability.

  • Ignacio Rockwill

    I agree with @andrewtubbiolo:disqus that a lot of the fuzziness is due to film cooling. The dark spots from our viewpoint could either be inconsistencies in the film cooling (darker implies cooler gas and an over abundance of film cooling) or MCC combustion performance from the main injector.

  • Ignacio Rockwill

    Plain Jane. Bought the turbopumps from Barber Nichols just like the first Merlins did. I think there’s probably more technology in their composite tanks than anywhere else on the rocket.

  • Lee

    I’m not sure it is from the film cooling. I don’t see that effect in other film cooled engines. Also, I don’t see such a raggedy exhaust in other engines. I have my suspicions as to what is going on, but I’ll leave it to others to guess for themselves.

  • Ignacio Rockwill

    Can you give us a hint at least? 🙂

  • Lee

    Let’s just say the VG folks don’t have a stellar record when it comes to engineering.

  • Ignacio Rockwill

    Am I correct in thinking that the dark parts of the plume close to the nozzle indicate cooler gas in that area?

  • Lee

    Yes, most likely. However, it’s not the presence of the darker areas that is troubling. It’s the fact they are changing all over he11 and gone during the entire burn. This (and the amazingly ragged plume, I don’t recall that from any other engine either) indicates instability to me.

  • duheagle

    Agree that the plumes are not pretty. If the cause is combustion instability, said instability at least seems to be self-limiting rather than a positive feedback loop. If there was any tendency for things to oscillate out of control, both these videos show firing durations that should have exposed such problems. They didn’t. Given the problems VG has long had with its hybrids – including that hiccup just after start that is still there in the video of the most recent powered test – VO is doing pretty well, comparatively, with the Newtons.

    I wonder, though, if maybe the problem isn’t just that the test stand is at surface atmospheric pressure while both engines are optimized for high-altitude/vacuum operation.

  • Generally you just see the outer ring of fuel injectors pointed at the walls and flow is controlled by the diameter of the holes – no throttling. The black is probably from the unburned carbon in the fuel rich our layer, the H2 would be effectively clear. 5% or less deviation from nominal (10% peak-to-peak) is usually consider stable by CPIAC, but if you can SEE it, it’s probably a low frequency instability. That would imply a feed system coupling. That can be a test stand artifact just as much as a real system issue.

  • JS Initials

    I calculated the burn to last 3 minutes and 11 seconds. That burn time is long enough to put a payload into a LEO orbit with a high-G acceleration. Not quite SSTO, but a good 2-stage version when you consider that the first stage will be the launching aircraft.