Saturday, September 24, 2022

Odds of Artemis Rollback Just Skyrocketed - Plus Fling-a-Ding!

If you've heard this, you probably heard it as an absolute, but it technically isn't absolutely sure.  According the Artemis I blog, they won't decide for sure until tomorrow.  

NASA is foregoing a launch opportunity Tuesday, Sept. 27, and preparing for rollback, while continuing to watch the weather forecast associated with Tropical Storm Ian. During a meeting Saturday morning, teams decided to stand down on preparing for the Tuesday launch date to allow them to configure systems for rolling back the Space Launch System rocket and Orion spacecraft to the Vehicle Assembly Building. Engineers deferred a final decision about the roll to Sunday, Sept. 25, to allow for additional data gathering and analysis. If Artemis I managers elect to roll back, it would begin late Sunday night or early Monday morning.

The current five day track from the National Hurricane Center, NHC (as of 2PM EDT or 1800 UTC), shows the landfall has moved north, past Tampa Bay and up to (what appears to be) the Crystal River or Homosassa area, - 50 to 60 miles north of the area that was forecast last night through 8AM this morning and easily over 100 miles since the forecast plot I put up yesterday. 

The thing is, the afternoon model plots still have the NHC models the farthest east of all of them, and NHC typically isn't an outlier.  I've attempted to point out some of the points on the NHC track in the red color they use, to show how over almost all of the 5-day predictions, they're well east of all but one model family. 

On to the lighter side topic; what's a Fling-a-Ding?  An attempt to make a novel concept for rocket launchers seem a little less deadly serious.  

Space News reported this week that the very novel launch company, Spin Launch, has raised another $71 million for their attempts to build a centrifuge-based launcher that will fling an orbital rocket's upper stage high enough to replace a conventional booster or an airplane-drop for the upper stage. This raises their total funds raised to $150 million.  

In case you missed it, the company has already built a suborbital-class spin launcher, AKA rocket flinger, rocket yeeter, or others and tested it successfully.  

SpinLaunch built a smaller version of its centrifuge at Spaceport America in New Mexico, 33 meters in diameter, for suborbital tests. The system launched its first vehicle in October 2021 and has conducted nine tests to date, although it has disclosed few details about the speed and peak altitude of those tests.

“SpinLaunch’s mission is to bring the world low-cost, sustainable access to space. We’ve taken a big step in that direction with the completion of our 33-meter Suborbital Mass Accelerator,” said Jonathan Yaney, chief executive of SpinLaunch, “retiring the technical risk as we prepare the way for the construction of our full-size Orbital Launch system.”

Someone's saying to themselves, "33 meters?  Like 100 feet?"  Exactly. 

The company has said that the orbital class Flinger will be 100 meters across or about 330'.  They expect to make orbital launches with the bigger accelerator as early as 2026, but have a few additional hurdles to overcome.  First off, it can't be at Spaceport America (where this one is) due to overflight issues and they don't have a location for it at this time. Second off is the whole nobody has done this yet, and I gather the requirements for mechanical design of the satellites might be bit unprecedented.  

[Vice President Randy] Villahermosa mentioned in his talk the company was planning “an intermediate service around 2024 that will use some of our satellite and launch tech.” He didn’t elaborate on the service but said that the company will release additional details in the coming months.

SpinLaunch, in addition to the launch system, is working on satellites optimized for it. They include a 12U cubesat bus and a 200-kilogram satellite, the latter equal to the payload capacity of the orbital system. A 12U cubesat prototype will launch as soon as January, he said, but disclose the launch provider.

I have lots of questions about this sort of launch mechanism.  I don't believe the concept is all new and has been talked about before, but the speeds of a booster are nothing to take lightly although as part of a launch system they don't need to achieve many times the speed of sound.  When Virgin Orbit drops a craft from their 747 Cosmic Girl, they're not even going Mach 1.  A point in their favor is that their flight path is almost entirely parallel to the ground, while a conventional rocket takes off vertically and then starts to pitch over very early in the flight, to gain that horizontal speed component.  A substantial amount of fuel is used to get moving vertically while gaining speed going horizontally.  

A very long winded way of saying that the angle of the launcher silo (right word) on that centrifuge looks too vertical to me.  Which pales in comparison to what I see as the real problem: how do they change the path of the rocket upper stage going at hypersonic speeds in the centrifuge to going straight out that launch tube?  That seems to be a really critical timing.  And what about the shock of the acceleration from changing directions.  They can accelerate in a vacuum by closing off the silo, but sooner or later they've got to open it and the pressure of that air coming in is going to hammer that upper stage like a some sort of monster.  I'll bet it's an incredible amount of G-shock. 

“We get asked a lot about the g’s,” he said. “It’s a very gentle 10,000 g’s.”  ["he" is apparently VP Villahermosa.] 


  1. Well, obviously it just wouldn't do to use a harsh 10,000 g's. Is this serious?

    1. Is it serious? I'm more confident that they're a real company and are really trying to raise funds than that what they're proposing will actually work when it's scaled up and reduce the cost of getting to orbit.

      They've been around for a while. They have a YouTube channel and they talk about test flights through #8, posted this past April.
      Spinlaunch Channel.
      Video #8 has a camera mounted on the vehicle.

      I should have watched the videos before I wrote the piece. They get around opening the problem from opening the silo and explosive pressure that I mentioned by having a seal that breaks when the projectile (vehicle) goes through it.

    2. 1) There's a French phrase that may be applicable: "That's a great idea- too bad it doesn't work".

      2) Mythbusters fired a ping-pong ball at supersonic(?) velocity using an evacuated tube and dumping air into it. The secret to affordable orbit appears to be aluminum foil and duct tape...

    3. Maybe it was saran wrap and not aluminum foil... Regardless, get around the absurd G forces by scaling up the pneumatic tube transport idea used by banks at their drive-up ATMs.
      Tangent: I recommend reading "The Victorian Internet".

  2. They seem to be finding investors for the flinger. I'd rather see acceleration. using a very long barreled gun (Gerald Bull) because the G-load isn't as sudden or nearly as heavy and it isn't multi-axis, if you want to depart from the norm, etc., etc. But what do I know. Somebody thinks that the flinger will work. Why not a nautical launch?

    1. There have been long barreled guns - cannons - suggested for decades, as a way to replace the booster stage. I'm with you in thinking that it seems better. Perhaps an electromagnetic "rail gun" kind of approach - which has also been suggested many times.

  3. Not a lot of commercial satellites can handle accelerations above the typical rocket launch. 10,000G's? Yeah, no. It was and is one of the main things against gun-launchers, even a multi-ignition chambered gun like what the Nazis and Gerald Bull tried to do (that would be a barrel with multiple ignition chambers staged along part of the length of the barrel.)

    Even Rail Guns won't be commercially viable unless they can hold the acceleration down to a reasonable level.

    Why this matters: One of the problems with the Sprint ABM was that the vehicle could accelerate faster than the electronics could handle. They finally got that solved, but that was under 'continuous acceleration' (meaning getting faster and faster and faster.) BANG acceleration, like going from a vacuum to atmosphere or from a gun is just a horrible amount of stress.

    You can mitigate some of that stress by putting your launcher (spin, gun, rail-gun) higher up in the atmosphere, up where human breathing is difficult. But that will take away a lot of the cost-benefit and locations available for launching.

    And if it is so easy to launch from high altitude, why don't more rocket launches launch from up above the cloud layer?

    Now, spin launching, just like gun or rail-gun launching, would be an effective way in a minimal-atmosphere reduced-or-minimal gravity environment. Like on the Moon, or Mars, or large asteroids. So, yes, work out the bugs in a heavy-atmosphere high-gravity environment. Then move/build the darned things off Earth into a better environment.

    It's easier and cheaper to make simple electronics for aircraft and missiles than it was (until the trick was learned) to make for gun-rounds. Not a lot of commercial customers are going to want to up-build their payloads to handle high-G launching stresses of any kind.

    Rockets (and Orion Drives) that provide continuous low-level G-stress accelerations are the way to go for cheap-cheap launches.

    1. But only until the Greenies outlaw rockets!

    2. OMG, outlaw rockets that produce water vapor! Save the planet from... water!!! Or something.

      Yet Red China is still using very dangerous, toxic, poisonous and horrid fuels and nobody in or out of Red China is saying much of anything.

    3. Not to mention dropping the boosters, still outgassing toxic fuels, onto populated, rural areas of the PRC.

    4. Eh, just dropping them on peasants and non-Han people, so no biggie.

  4. see, God doesn't like Artemis either.

  5. NASA just needs to bite the bulled and roll back. Murphy says if they do that, the weather Tuesday will be perfect, and if they don't do that it'll rain like a cow peeing on a flat rock. Either way, NASA looses.

    Don't even try to tempt Fate, boys.

    As for Spin Launch, it's a great concept because getting through the atmosphere soup for the initial part of the boost accounts for a large majority of propellant expended. Besides, you're leaving behind a large motor, tankage, and propellant mass.

    Here's to hoping it'll work out, guys!

  6. I'll be interested to see where the mass used to counterbalance goes at mach 7(?).
    Opposite mach 7...into what?