There is some previous discussion of SpinLaunch in the smallsat launchers thread starting athttps://forum.nasaspaceflight.com/index.php?topic=38583.msg1729999#msg1729999
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.
More detailed discussion about this approach here: https://forum.nasaspaceflight.com/index.php?topic=38583.380, including opinions from our resident launch experts.
Quote from: john smith 19 on 02/25/2018 11:30 amQuote from: Bananas_on_MarsThe 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...
Quote from: Bananas_on_MarsThe 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.
The rocket part has to be able to withstand some 1000g, so it should be beefy enough to survive the transition.
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.
Quote from: su27k on 06/16/2018 02:54 amMore 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.Quote from: Bananas_on_Mars on 02/25/2018 03:13 pmQuote from: john smith 19 on 02/25/2018 11:30 amQuote from: Bananas_on_MarsThe 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...Quote from: HMXHMX on 02/25/2018 04:19 pmI 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?
Quote from: intrepidpursuit on 06/16/2018 05:23 amQuote from: su27k on 06/16/2018 02:54 amMore 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.Quote from: Bananas_on_Mars on 02/25/2018 03:13 pmQuote from: john smith 19 on 02/25/2018 11:30 amQuote from: Bananas_on_MarsThe 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...Quote from: HMXHMX on 02/25/2018 04:19 pmI 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.
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.
Quote from: Bananas_on_Mars on 06/16/2018 04:53 pmOr 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.
... You don't get that kind of investment for crazy ideas, ...
Quote from: Bananas_on_Mars on 06/16/2018 04:53 pmOr 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.
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?
If this made sense in any way shape or form, artillery would look a lot different than it does today.
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.