SpinLaunch: General Company and Development Updates and Discussions

[Robotbeat]

Reminds me of: https://patents.google.com/patent/US3962537A/en
Gun launched reconnaissance system

https://medium.com/war-is-boring/the-u-s-army-wanted-to-launch-t-v-cameras-from-howitzers-54a72f80dfe

[Steven Pietrobon]

Anyone know the dates of test flights 2 to 6?

[jongoff]

{emphasis mine} Yes, that's quite an impressive hole-in-the-ground!  Not sure about anyone else, but the recoveries I'm used to seeing don't normally require a digger. 

Diggers are lot cheaper to own and operate than ships and helicopters.



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Ah yes, lithobraking - the best method of recovery.

My guess from looking at the dart in the video is that this is a not exactly representative all-steel dart. It's probably meant to simulate the mass properties of the sabot + rocket combination for dialing in the exit behavior as they slowly turn the separation speed up. For a flight version, the sabot is going to have a much lower ballistic coefficient once it has split in 2-4 pieces, and ejected the rocket inside. Which might make a parachute recovery more feasible, if they want to go that route.

They're incrementally testing things, burning down risks little by little, slowly turning up the RPMs on the centrifuge, expanding the envelope little by little. Given that their marginal testing cost is probably pretty modest, this seems pretty savvy to me.

~Jon

[Robotbeat]

Gotta imagine they'll add a small rocket, or at least a gas generator, to the base of the sabot/aeroshell to reduce drag. Act as another stage, potentially.

[jongoff]

Gotta imagine they'll add a small rocket, or at least a gas generator, to the base of the sabot/aeroshell to reduce drag. Act as another stage, potentially.

I don't think they actually need to. The numbers I head for how much it slows down on its way through the atmosphere was actually kind of modest. Sure the deceleration right at launch is kind of brutal, but it's past airplane cruising altitude in like 6-7s if I'm doing the math right. I'm morbidly tempted to do an excel-based ghetto 3DOF simulator again...

~Jon

[edzieba]

They're not limited by the geometry required for gun-launch, so no real need for base-bleed to compensate for the boat-tail: just omit the boat-tail. You can have an optimal pointed tail instead and be a near-perfect Sears–Haack body.

[Robotbeat]

They're not limited by the geometry required for gun-launch, so no real need for base-bleed to compensate for the boat-tail: just omit the boat-tail. You can have an optimal pointed tail instead and be a near-perfect Sears–Haack body.

Oh that’s a good point. I still think it might make sense to turn the aeroshell into a little recoverable rocket stage eventually. Would improve performance and require less hardware to be expended. They’re recovering them anyway.

[jongoff]

They're not limited by the geometry required for gun-launch, so no real need for base-bleed to compensate for the boat-tail: just omit the boat-tail. You can have an optimal pointed tail instead and be a near-perfect Sears–Haack body.

Oh that’s a good point. I still think it might make sense to turn the aeroshell into a little recoverable rocket stage eventually. Would improve performance and require less hardware to be expended. They’re recovering them anyway.

It sounds like they may be thinking in the direction. I imagine the ballistic coefficient for a dart with a rocket in it, flying nose first vs for two dart halves without a rocket inside flying sideways are probably *very* different.

~Jon

[Robotbeat]

I wonder if they read Neal Stephenson's Termination Shock, which featured large recoverable shells shot into the stratosphere and recovered with guided parachutes into big Mr. Stevens-style nets in the desert. Basically identical.

[Asteroza]

They're not limited by the geometry required for gun-launch, so no real need for base-bleed to compensate for the boat-tail: just omit the boat-tail. You can have an optimal pointed tail instead and be a near-perfect Sears–Haack body.

Would that balance out better on the rotor, compared to a conventional hypercone projectile?

[edzieba]

They're not limited by the geometry required for gun-launch, so no real need for base-bleed to compensate for the boat-tail: just omit the boat-tail. You can have an optimal pointed tail instead and be a near-perfect Sears–Haack body.

Would that balance out better on the rotor, compared to a conventional hypercone projectile?

Shouldn't make a big difference, the chamber is evacuated so CoP should not be a concern until exit. Internal configuration will have a bigger effect on CoM.

[Rondaz]

Watch a SpinLaunch test payload soar with on-board cam

[jongoff]

Watch a SpinLaunch test payload soar with on-board cam

I'm looking forward to seeing their next flight test in-person next week.

~Jon

[TrevorMonty]

Watch a SpinLaunch test payload soar with on-board cam

I'm looking forward to seeing their next flight test in-person next week.

~Jon

Don't forget your hard hat

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[Asteroza]

I'm looking forward to seeing their next flight test in-person next week.

~Jon

Don't forget your hard hat

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Hardhat ain't gonna save you from an oversized lawndart...

[TrevorMonty]

Watch a SpinLaunch test payload soar with on-board cam

I'm looking forward to seeing their next flight test in-person next week.

~Jon

Don't forget your hard hat

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I see you didn't forget your hard hats Jon.

https://twitter.com/rocketrepreneur/status/1527397853793878016?t=JuKU-ac-1vhJra8RrafkYA&s=19

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[Asteroza]

Watch a SpinLaunch test payload soar with on-board cam

Yeet Snail 3300 is a nice touch.

I'm looking forward to seeing their next flight test in-person next week.

~Jon

Don't forget your hard hat

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I see you didn't forget your hard hats Jon.

https://twitter.com/rocketrepreneur/status/1527397853793878016?t=JuKU-ac-1vhJra8RrafkYA&s=19

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[Navier–Stokes]

[Robotbeat]

There should be FAA NOTAMs or something for each flight, right?

How many flights have they had since flight #8? Are they still flying regularly?

[jongoff]

There should be FAA NOTAMs or something for each flight, right?

How many flights have they had since flight #8? Are they still flying regularly?

Well, there was the one I went to see with my family in May. I think they were saying they planned on doing flight tests at least once a month, other than monsoon season where weather would preclude getting to the test site.

~Jon