Countdown to new smallsat launchers

[Welsh Dragon]

That's going to put some .... interesting ... demands on payload structure along multiple axes.

[vaporcobra]

Stealth space catapult startup SpinLaunch is raising $30M
BY JOSH CONSTINE
3 hours ago

What if instead of blasting cargo into space on a rocket, we could fling it into space using a catapult? That’s the big, possibly crazy, possibly genius idea behind SpinLaunch. It was secretly founded in 2014 by Jonathan Yaney, who built solar-powered drone startup Titan Aerospace and sold it to Google. Now TechCrunch has learned from three sources that SpinLaunch is raising a massive $30 million Series A to develop its catapult technology.

https://techcrunch.com/2018/02/22/spinlaunch/amp/?__twitter_impression=true

I truly cannot fathom how this has raised $10m... unless I wildly misunderstand basic physics, this company would have to be miles beyond the cutting edge of materials science to be even close to making this work. Even, say, if they somehow convinced Hawaii to let them set up on top of Mt. Kilauea.

[groundbound]

That seems to share some attributes with a miniature launch loop. I suspect it also shares some of the problems inherent in launch loops.

[vaporcobra]

That seems to share some attributes with a miniature launch loop. I suspect it also shares some of the problems inherent in launch loops.

Oooooh this is what it reminds me of. Probably a nearly-identical concept, and just as utterly stupid https://www.kickstarter.com/projects/391496725/the-slingatron-building-a-railroad-to-space

[jongoff]

That seems to share some attributes with a miniature launch loop. I suspect it also shares some of the problems inherent in launch loops.

Oooooh this is what it reminds me of. Probably a nearly-identical concept, and just as utterly stupid https://www.kickstarter.com/projects/391496725/the-slingatron-building-a-railroad-to-space

No, their concept is a lot more simple and elegant than the slingatron. There are still some high pucker factor issues to resolve IMO (the biggest one being the dynamics of going from vacuum to air IMO), but from what I've seen of their approach it's actually fairly clever and well thought-out. They still have an expendable rocket in there, so I'm somewhat skeptical they'll be able to hit the price they're talking about, but if they can both raise the money they need, and make their system work reliably, I think they've got a shot of filling a niche even if they miss their target by a factor of 2. Though I think their concept would be much more useful for propellantless launch of ISRU materials from the lunar surface...

~Jon

[john smith 19]

Stealth space catapult startup SpinLaunch is raising $30M
BY JOSH CONSTINE
3 hours ago

What if instead of blasting cargo into space on a rocket, we could fling it into space using a catapult? That’s the big, possibly crazy, possibly genius idea behind SpinLaunch. It was secretly founded in 2014 by Jonathan Yaney, who built solar-powered drone startup Titan Aerospace and sold it to Google. Now TechCrunch has learned from three sources that SpinLaunch is raising a massive $30 million Series A to develop its catapult technology.

https://techcrunch.com/2018/02/22/spinlaunch/amp/?__twitter_impression=true

OK Theoretically you can do a slow spin up in some kind of evacuated chamber or tunnel (not too stressful) before hitting the launch direction. Historically the big problem with all mass driver concepts is they are difficult to point in different directions.

But

Centripetal acceleration forces are still massive.

To give the equivalent of the F9 stage separation velocity (about M6, not even 1/2 orbital velocity) you're going M6 at ground level, and as Jon Goff noted it's like hitting a brick wall. We know something about this due to discussions about the acceleration profiles of someone sky diving from orbit

Then of course there is the engineering of an air lock that can pass an object moving at M6+ (because pumping down a really big vacuum chamber is quite slow).  I'm thinking a falling metal foil roll with electromagnets pulling it down, with a solid (slower moving) backup cover.

Naturally the heating will be severe. We are above the Sprint ABM here (that broke M1 30m after launch).

And of course there is the control system that stops it plowing into the side of the airlock as it transitions from vacuum to sea level (or near sea level pressure) air.

The CFD will be quite interesting. That transition sounds turbulent. Supposedly modelling turbulence has gotten a lot better.  I think some scale models may still be needed.

Then the engine(s). Liquid slosh is likely to be a problem (the US Army has done work looking at spinning tanks of fluid) but you'll want the higher Isp. The Germans engineered a liquid ramjet assisted artillery shell with a 350Km range in WWII, so not impossible.

A big issue is how much extra effort do payloads have to make to cope with this environment. Engineering the LV is your problem, but if building payloads for these launch conditions is a black art they may struggle to find customers.

[vaporcobra]

That seems to share some attributes with a miniature launch loop. I suspect it also shares some of the problems inherent in launch loops.

Oooooh this is what it reminds me of. Probably a nearly-identical concept, and just as utterly stupid https://www.kickstarter.com/projects/391496725/the-slingatron-building-a-railroad-to-space

No, their concept is a lot more simple and elegant than the slingatron. There are still some high pucker factor issues to resolve IMO (the biggest one being the dynamics of going from vacuum to air IMO), but from what I've seen of their approach it's actually fairly clever and well thought-out. They still have an expendable rocket in there, so I'm somewhat skeptical they'll be able to hit the price they're talking about, but if they can both raise the money they need, and make their system work reliably, I think they've got a shot of filling a niche even if they miss their target by a factor of 2. Though I think their concept would be much more useful for propellantless launch of ISRU materials from the lunar surface...

~Jon

Thanks for your insight, Jon - if you think it's not necessarily insane, I'll take your word for it! In that case, I look forward to seeing /hearing about their progress Still skeptical about the basic physical feasibility of moving from vacuum to atmosphere (even if graduated) at hypersonic speeds, but I'll wait and see before dismissing them outright.

[Lars-J]

Going through the atmosphere at 9 km/s ain't like dusting crops, boy! 

[Dao Angkan]

I guess that you'd want to test this out at as high an altitude as possible. La Rinconada, Peru has an altitude of 5,100m, with an air pressure of about half of sea level. I'd see how plausible it was there first.

[ringsider]

Here is the Hawaii legislature bill to give them $25M:-

https://www.capitol.hawaii.gov/session2018/bills/SB2703_.HTM

Astonishing.

Here is some of the evidence in the recent hearing:-

https://www.capitol.hawaii.gov/Session2018/Testimony/SB2703_TESTIMONY_WAM_02-23-18_LATE.PDF

[as58]

How did the Hawaii legislature bill even get started? Funding SpinLaunch feels like a very strange way to spend more than $20 million of public money.

[groundbound]

How did the Hawaii legislature bill even get started? Funding SpinLaunch feels like a very strange way to spend more than $20 million of public money.

It also seems odd given the recent problems with the TMT. How would that cause cultural concerns with some native Hawaiians but objects in the same area leaving at orbital velocities somehow be OK?

[HMXHMX]

How did the Hawaii legislature bill even get started? Funding SpinLaunch feels like a very strange way to spend more than $20 million of public money.

It also seems odd given the recent problems with the TMT. How would that cause cultural concerns with some native Hawaiians but objects in the same area leaving at orbital velocities somehow be OK?

It doesn't exit the launcher at orbital velocities, rather it is comparable to tube artillery projectile velocity.

[Bananas_on_Mars]

It doesn't exit the launcher at orbital velocities, rather it is comparable to tube artillery projectile velocity.

Modern Artillery seems to max out around 1000m/s. If we assume the "first stage" will provide a speed similar to conventional first stages on a 2 stage rocket, that would mean around 2000m/s (Mach 6).
By the name of the company, i would suspect they're going for something like a centrifuge launcher.

Their rocket (second stage) is shaped like a reentry vehicle on an ICBM.

If they run in a vacuum first, during the firing the launch vehicle shouldn't experience more than 1 Mach more while exiting the mechanism.
There might be ways to further reduce the pressure difference when exiting the "launcher", but it might be unnecessary.
The rocket part has to be able to withstand some 1000g, so it should be beefy enough to survive the transition.

Edit:
I found an article about a similar concept, maybe Spinlaunch is even an spin-off (pun intended) of Hyper V technologies mentioned here

[john smith 19]

Modern Artillery seems to max out around 1000m/s. If we assume the "first stage" will provide a speed similar to conventional first stages on a 2 stage rocket, that would mean around 2000m/s (Mach 6).
By the name of the company, i would suspect they're going for something like a centrifuge launcher.

I think you'll find most expendable rockets  split the Mach range roughly in half and the first stage shuts down around M10.

Their rocket (second stage) is shaped like a reentry vehicle on an ICBM.

Or like the Sprint ABM, which is what you'd expect if you wanted to do high Mach numbers at near sea level pressure.

If they run in a vacuum first, during the firing the launch vehicle shouldn't experience more than 1 Mach more while exiting the mechanism.

This statement makes no sense. 1000m/s is about 3Mach numbers with a SL Mach velocity of 340m/s

There might be ways to further reduce the pressure difference when exiting the "launcher", but it might be unnecessary.

Depends on the radius and the acceleration.

The rocket part has to be able to withstand some 1000g, so it should be beefy enough to survive the transition.

Trouble is not the LV, it's how much effort will customers have to put in to make payloads that can survive their launch plan.

As always with these ideas the question is "Can your plan eliminate the development of a complete stage?"
If it can't then you're still developing a two stage (or more) to orbit vehicle in addition to this launch assist device. Somewhere between 20 and 40 ELV's have now been developed, so it's not like it's never been done before and the strategies to lower development cost are quite well known.

I will note that at launch the rocket is at its heaviest and burns the most amount of propellant to give the least amount of delta V. The question then becomes "What is the simplest, cheapest way to improve this, other than simply building a bigger rocket?"

Developing a launch assist technology so good it can eliminate a whole stage (or is so cheap to develop it does not add a whole stage development budget to the project) is pretty tough.

I have yet to see a smallsat LV company that started with "OK what's the most common size smallsat customers want, what orbits do they want and on average how much are they willing to pay and how many of them are there?" Then work the development plan (including the test firings) so they come out with an income above operating and development costs at the end. IE a profit.

[Bananas_on_Mars]

I think you'll find most expendable rockets  split the Mach range roughly in half and the first stage shuts down around M10.

I was comparing with Falcon 9 , Electron seems to stage at a similar speed.
Those are 2 stage rockets without boosters.

If they run in a vacuum first, during the firing the launch vehicle shouldn't experience more than 1 Mach more while exiting the mechanism.

This statement makes no sense. 1000m/s is about 3Mach numbers with a SL Mach velocity of 340m/s

There might be ways to further reduce the pressure difference when exiting the "launcher", but it might be unnecessary.

Depends on the radius and the acceleration.

I guess i have to reword my thoughts, because i think you misunderstood me.
If the acceleration takes place in a vakuum, and the mechanism is located at sealevel, there's a pressure difference of ~ 1 bar. When the projectile leaves the mechanism, the ambient air rushing in can't be faster than Mach 1, so that adds maximum 1 Mach to the relative airspeed while the projectile leaves the mechanism.

You can temporarily reduce ambient pressure at the outlet through some funny means (a carefully timed explosion might do, or with jet engines combined with something like a venturi nozzle).

The rocket part has to be able to withstand some 1000g, so it should be beefy enough to survive the transition.

Trouble is not the LV, it's how much effort will customers have to put in to make payloads that can survive their launch plan.

I did a quick calculation, a centrifugal launcher that supplies 2000m/s and has a 20m radius would mean about 20.000g...

[HMXHMX]

It doesn't exit the launcher at orbital velocities, rather it is comparable to tube artillery projectile velocity.

Modern Artillery seems to max out around 1000m/s. If we assume the "first stage" will provide a speed similar to conventional first stages on a 2 stage rocket, that would mean around 2000m/s (Mach 6).
By the name of the company, i would suspect they're going for something like a centrifuge launcher.

Their rocket (second stage) is shaped like a reentry vehicle on an ICBM.

If they run in a vacuum first, during the firing the launch vehicle shouldn't experience more than 1 Mach more while exiting the mechanism.
There might be ways to further reduce the pressure difference when exiting the "launcher", but it might be unnecessary.
The rocket part has to be able to withstand some 1000g, so it should be beefy enough to survive the transition.

Edit:
I found an article about a similar concept, maybe Spinlaunch is even an spin-off (pun intended) of Hyper V technologies mentioned here

To my knowledge they have nothing to do with Slingatron-type predecessors.  You should think about their mechanical launcher as the equivalent of air-launching, nothing more.

I know the details, and even though haven't signed an NDA I want to respect their confidences.  I got a pretty good brief, along with many others, at their December holiday party. 

[Welsh Dragon]

HMXHMX, would you say this lot are serious and plausible then, according to your knowledge and experience?

My issue with this approach is that, however you do it, the g-forces involved are going to be order(s) of magnitude higher than in a conventional launch (someone correct me if I'm wrong). This would require specific builds for anyone planning to launch with them. For instance, my assumption would be that a conventional cubesat wouldn't work. This creates a chicked-and-egg problem. Why would anybody change they design and build practices for a specific launcher like this, and on the other hand, why would this launcher be build if there aren't any suitable payloads going for it?

Two ways to sort this problem that I see is that either they offer launches so much cheaper than any other alternative that people are willing to custom build for them, or that the launch isn't anywhere near as high-g as I'm thinking it'll be. Either seems unlikely to me, but lets hope I'm proven wrong.

[HMXHMX]

HMXHMX, would you say this lot are serious and plausible then, according to your knowledge and experience?

My issue with this approach is that, however you do it, the g-forces involved are going to be order(s) of magnitude higher than in a conventional launch (someone correct me if I'm wrong). This would require specific builds for anyone planning to launch with them. For instance, my assumption would be that a conventional cubesat wouldn't work. This creates a chicked-and-egg problem. Why would anybody change they design and build practices for a specific launcher like this, and on the other hand, why would this launcher be build if there aren't any suitable payloads going for it?

Two ways to sort this problem that I see is that either they offer launches so much cheaper than any other alternative that people are willing to custom build for them, or that the launch isn't anywhere near as high-g as I'm thinking it'll be. Either seems unlikely to me, but lets hope I'm proven wrong.

I would say they are as serious as any of the other one or two dozen small launch vehicle start-ups that have raised >$5m seed funding.  I've not spent any time analyzing their approach, so I can't speak to plausibility.  Seriousness alone is no measure of likelihood of success, of course, either technically or in the marketplace.  I know that from personal experience. 

[john smith 19]

I was comparing with Falcon 9 , Electron seems to stage at a similar speed.
Those are 2 stage rockets without boosters.

However as SX boosters fly a trajectory that allows recovery they seem to put more burden on the upper stage in terms of the split of delta V to get to orbit.

I guess i have to reword my thoughts, because i think you misunderstood me.
If the acceleration takes place in a vakuum, and the mechanism is located at sealevel, there's a pressure difference of ~ 1 bar. When the projectile leaves the mechanism, the ambient air rushing in can't be faster than Mach 1, so that adds maximum 1 Mach to the relative airspeed while the projectile leaves the mechanism.

You can temporarily reduce ambient pressure at the outlet through some funny means (a carefully timed explosion might do, or with jet engines combined with something like a venturi nozzle).

Ahh. This makes much more sense. In fact IIRC you need something like a 2 bar absolute pressure difference to get M1 flow through a nozzle. It's not so much the density it's the relative density between near zero (say 1 Pa Vs 100 000 Pa in the atmosphere).

You're right you can do tricks to lower pressure through diffusers (often using high pressure steam, or a jet engine exhaust) but that's sort of delaying the problem. What you probably want is more like a gradual shifting, from near vacuum till full SL free flight air pressure.

IIRC Sandia did a test on a wheeled (or skid equipped) test sled that reached M8, by driving through a plastic tunnel loaded with Helium at Sea Level. Of course this is real one-shot testing, that's very difficult to repeat.

I did a quick calculation, a centrifugal launcher that supplies 2000m/s and has a 20m radius would mean about 20.000g...

Is that a decimal point or have you mis placed a comma? 20g is less than an ICBM warhead at burn out.  20 000g is more like those GPS guided artillery shells the USN is currently using.  Obviously both are possible but the latter needs a much more specialized skill set to build.  Likewise quite small increases in diameter can lower the centripetal g load quite a lot.