SpinLaunch: General Company and Development Updates and Discussions

[intrepidpursuit]

Now that SpinLaunch has managed to raise $40 million from investors including respected aerospace companies (Airbus) I think it is worth a brief discussion.

The basic concept, in case you aren't familiar, is that they will use electricity to spin a payload in a centrifuge and then catapult it into space. The concept images show a small slender projectile with fins as the payload. From what I've seen, it is unclear whether that projectile includes an engine, or whether they intend to reach orbit, though both are implied.

The founder Jonathan Yaney is an amateur pilot and has experience in IT and construction. The story they tell starts with a team of underwater welders joining on to build the prototype.

I'll put my thoughts on them in a second post. Below are links to the most relevant information I can find. Their website just has a logo and a "login" button that doesn't do anything.

https://www.geekwire.com/2018/spinlaunch-raises-40m-airbus-google-others-space-catapult/

http://spinlaunch.com/

[intrepidpursuit]

They mention that a projectile would be launched at 3000 to 5000 mph. That is already fast enough to tear apart all but the most robust hypersonic vehicle. The vehicle will have to be able to withstand massive g-forces in the centrifuge and incredible temperatures on the flight up. Getting a vehicle with no propulsion to maintain useful speed up to a thinner atmosphere seems impossible.

Best case, this is replacing the airplane stage of an air launch system, but with some huge downsides. I don't understand how this could possibly be more cost effective than an airplane for similar performance, for a long list of reasons.

This project is so insane, I have to wonder if the people founding it even think it is a real thing. The biggest problems are really very basic physics.

[gongora]

There is some previous discussion of SpinLaunch in the smallsat launchers thread starting at
https://forum.nasaspaceflight.com/index.php?topic=38583.msg1729999#msg1729999

[Bob Shaw]

Sounds like 'spin' to me...

[intrepidpursuit]

There is some previous discussion of SpinLaunch in the smallsat launchers thread starting at
https://forum.nasaspaceflight.com/index.php?topic=38583.msg1729999#msg1729999

Yes, I saw the previous mention that they exist. We have more info and they have more money now, as I mentioned.

[ThePhugoid]

They mention that a projectile would be launched at 3000 to 5000 mph. That is already fast enough to tear apart all but the most robust hypersonic vehicle. The vehicle will have to be able to withstand massive g-forces in the centrifuge and incredible temperatures on the flight up. Getting a vehicle with no propulsion to maintain useful speed up to a thinner atmosphere seems impossible.

Best case, this is replacing the airplane stage of an air launch system, but with some huge downsides. I don't understand how this could possibly be more cost effective than an airplane for similar performance, for a long list of reasons.

This project is so insane, I have to wonder if the people founding it even think it is a real thing. The biggest problems are really very basic physics.

Yep, I have no idea how investors tied to Alphabet could even begin to associate their name with this.

1. As you've pointed out, the projectile has to withstand lateral centrifugal loads that would need the beefiest structure known to man to survive.  Ideally you'd want said thing to be solid metal, which would be nonsense since it presumably needs to get some customer's payload into orbit.

2. After said thing exits centrifuge at speeds faster than any railgun or other cannon have achieved, there's the immediate transition to the atmosphere starting with a sonic boom that would again try to tear the projectile apart.  Again ideal to have it made of solid something like a slug, but would again be nonsense since it still has a long mission ahead to get into orbit.

3. Does the projectile have propulsion? Does it start ignition immediately after exit? Probably not since the proposers are suggesting it will be much simpler than existing launchers. This would mean it has to overcome gravity and drag losses that will compound against it since there is no dV provided after firing.

4. Assuming the projectile is given enough energy to reach an exoatmospheric apogee, there's still the problem of a circularization maneuver to inject it. This guarantees it must have some form of propulsion onboard, which is sizable given it currently has a perigee at earth's center and must be raised *at least* 6578 km. That propulsion system (let alone the payload and fairing system) will have had to have survived the ridiculous chain of events that preceded this circularization. No propulsion or payload designer on this green earth would touch this problem.

This thing would make more sense as a weapon system designed to target far and away structures using projectiles made of solid unobtanium.

If they're looking to put something into orbit though, I wish them luck.  They'll need it.

[su27k]

More detailed discussion about this approach here: https://forum.nasaspaceflight.com/index.php?topic=38583.380, including opinions from our resident launch experts.

[intrepidpursuit]

More detailed discussion about this approach here: https://forum.nasaspaceflight.com/index.php?topic=38583.380, including opinions from our resident launch experts.

Great discussion! Had a hard time finding it since no one says "spinlaunch" later in the conversation. Still think it warrants its own thread since they are raising more money.

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...

That's the calculation I was looking for. They have to make an upper stage engine that can survive those forces, then they have to get payload that can survive it. A solid chunk of metal would not come out of 20,000g unscathed.

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.

Is there some piece we are missing here that would make this thing possible? Have they addressed the seemingly insurmountable issues of the centripetal forces at launch and the drag through the low atmosphere?

[Bananas_on_Mars]

More detailed discussion about this approach here: https://forum.nasaspaceflight.com/index.php?topic=38583.380, including opinions from our resident launch experts.

Great discussion! Had a hard time finding it since no one says "spinlaunch" later in the conversation. Still think it warrants its own thread since they are raising more money.

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...

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.

Is there some piece we are missing here that would make this thing possible? Have they addressed the seemingly insurmountable issues of the centripetal forces at launch and the drag through the low atmosphere?

Their Launch vehicle has the shape of a Bullet, with a seam line going front to back. I assume the whole thing we're seeing in the pictures is essentially a payload fairing. That thing doesn't look like it's built to survive those many g's of a centrifuge. My current guess is they use a "spinny thingy" to store the energy needed to throw the projectile out of the atmosphere, the vehicle is accelerated linear. Once out of the atmosphere the fairing separates and a second stage takes over.

[intrepidpursuit]

More detailed discussion about this approach here: https://forum.nasaspaceflight.com/index.php?topic=38583.380, including opinions from our resident launch experts.

Great discussion! Had a hard time finding it since no one says "spinlaunch" later in the conversation. Still think it warrants its own thread since they are raising more money.

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...

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.

Is there some piece we are missing here that would make this thing possible? Have they addressed the seemingly insurmountable issues of the centripetal forces at launch and the drag through the low atmosphere?

Their Launch vehicle has the shape of a Bullet, with a seam line going front to back. I assume the whole thing we're seeing in the pictures is essentially a payload fairing. That thing doesn't look like it's built to survive those many g's of a centrifuge. My current guess is they use a "spinny thingy" to store the energy needed to throw the projectile out of the atmosphere, the vehicle is accelerated linear. Once out of the atmosphere the fairing separates and a second stage takes over.

No matter where the energy comes from though to get 2000m/s mechanically is going to put an incredible force on the payload. If they accelerate constantly over a 1km track it will take 1 second at 203g. It is hard to imagine how they could get constant acceleration over a track even that long with anything spinning, and the shorter the track the rougher the acceleration. 200g is already way too much for delicate satellites.

[Bananas_on_Mars]

Or 10km at 20g. But i'm sure they have some special tricks up their sleeve. You don't get that kind of investment for crazy ideas, and they already have a lot of hardware in that only picture i have seen.
I'm definitely looking forward to seeing more of their tech.

[ringsider]

Or 10km at 20g. But i'm sure they have some special tricks up their sleeve. You don't get that kind of investment for crazy ideas, and they already have a lot of hardware in that only picture i have seen.
I'm definitely looking forward to seeing more of their tech.

That picture:



is a rendering.

[Bananas_on_Mars]

Or 10km at 20g. But i'm sure they have some special tricks up their sleeve. You don't get that kind of investment for crazy ideas, and they already have a lot of hardware in that only picture i have seen.
I'm definitely looking forward to seeing more of their tech.

That picture:



is a rendering.

Mea maxima culpa...

It's a very good render...

[meekGee]

... You don't get that kind of investment for crazy ideas, ...

Where to begin...

-----
ABCD: Always Be Counting Down

[intrepidpursuit]

Or 10km at 20g. But i'm sure they have some special tricks up their sleeve. You don't get that kind of investment for crazy ideas, and they already have a lot of hardware in that only picture i have seen.
I'm definitely looking forward to seeing more of their tech.

But it is a crazy idea. Even if they spread acceleration across a huge area and manage to do that in a cost effective manner, they still have the problem of heating and drag on the way through the atmosphere. No way in hell this can launch a traditional payload and their stated audience is internet satellites and earth observation. If they find some use for putting solid blocks of something in orbit, I'm still not convinced they could do it in any cost effective manner.

[meekGee]

Or 10km at 20g. But i'm sure they have some special tricks up their sleeve. You don't get that kind of investment for crazy ideas, and they already have a lot of hardware in that only picture i have seen.
I'm definitely looking forward to seeing more of their tech.

But it is a crazy idea. Even if they spread acceleration across a huge area and manage to do that in a cost effective manner, they still have the problem of heating and drag on the way through the atmosphere. No way in hell this can launch a traditional payload and their stated audience is internet satellites and earth observation. If they find some use for putting solid blocks of something in orbit, I'm still not convinced they could do it in any cost effective manner.

To launch solid blocks, use a long cannon.

Spinning makes sense for slingshots, since the human arm is not very good at throwing.

If this made sense in any way shape or form, artillery would look a lot different than it does today.

-----
ABCD: Always Be Counting Down

[jongoff]

Is there some piece we are missing here that would make this thing possible? Have they addressed the seemingly insurmountable issues of the centripetal forces at launch and the drag through the low atmosphere?

I have to be careful about what I say, since the details were shared confidentially, but yes they know that they have to deal with centrifugal forces, yes, they've done a significant amount of analysis and testing, and no, it's not an insurmountable problem. Artillery shells regularly see 2-3x the acceleration this vehicle would see, and many modern shells have electronics and mechanisms. It is totally possible to harden structures for those kind of loads, especially when they're well known in advance.

As for drag going through the atmosphere, once again, yes they will slow down, but the square-cube law means that its easier to get a high ballistic coefficient (which means you decelerate less from drag) with a large vehicle than a small round.

That doesn't mean that their system is bound to obsolete all existing rockets, just that they've put more thought and effort into this than you can easily tell from the existing public articles.

~Jon

[jongoff]

If this made sense in any way shape or form, artillery would look a lot different than it does today.

Nope, they're trying to solve very different problems.

~Jon

[ringsider]

The video is interesting. I feel kind of sorry for the poor guys getting beaten up and run over by the locals, but the interesting bit is that in the introduction they mention they can't talk about technical details because of ITAR, then later they stated their prototype is being built "overseas". Hmm. ITAR, but overseas.

I read this on Wikipedia:-

SpinLaunch tried and failed to obtain US$25 million of Special Purpose Revenue Bonds from the 2018 Hawaii State Legislature via SB2703.

Upon checking, it looks like the legislation to give them $25m of state funds has been adjourned indefinitely:-

Hawaii House Bill 2559 (Adjourned Sine Die) (Adjourned without date)

https://legiscan.com/HI/bill/HB2559/2018

[john smith 19]

I have to be careful about what I say, since the details were shared confidentially, but yes they know that they have to deal with centrifugal forces, yes, they've done a significant amount of analysis and testing, and no, it's not an insurmountable problem. Artillery shells regularly see 2-3x the acceleration this vehicle would see, and many modern shells have electronics and mechanisms. It is totally possible to harden structures for those kind of loads, especially when they're well known in advance.

There is (theoretically) a way to side step the centripetal acceleration problem.

Implement the accelerator ring as an N-sided polygon of linear accelerators. At the corners the the vehicle is moving in a straight line, only subject to gravity.  It can then be reorientated with relatively low stress ready for entry into the next segment. It also means that the exit could be at several different directions to the Equator, rather than a single fixed direction.

The attraction is the acceleration can be relatively sedate. 10g's could get you to orbital velocity (at ground level) within 90 secs. The problems would be formidable. Heavy duty power electronics, fast acting control systems and some fairly large scale tunneling (or at least trench cutting, followed by covering over).   You'd want an exit ramp to put it on a fairly steep climbing trajectory and some fast acting foil shutters to retain vacuum.
Then there's the LV.
It'll need some serious TPS.
OTOH liquid fuel is not as difficult as you might think.  The Germans in WWII developed an artillery shell with a a 300Km+ range using the spin to inject liquid fuel into a circular duct (essentially a ramjet wrapped round an artillery shell). However this used the phenomenally dangerous Carbon Disulphide as the fuel. I'd guess they'd want something more benign today. Gerald Bull (who I like to think of as "The last of the long range gunmen"    ) reckoned solid propellant charges were adequate for circularizing to orbit, probably fired by a time delay or some kind of burnout trigger.
Using rotation to pressurize propellant was also the plan of Rotary Rocket.

The question with these concepts is not  "Can it be done?"

It is "Will commercial customers be prepared to swallow the costs inherent in making their payloads more rugged to survive this launch method than others" ?

GPS guided artillery shells are in use and are effective  but the electronics package was designed to do that as part of the customers requirements.

What happens when the launch price is very low but the payload has to be re-engineered from the ground up use the launch method?