SpinLaunch: General Company and Development Updates and Discussions

[Steven Pietrobon]

I've had some experience designing electronics for high g, designing a small board for a reusable projectile that ejected flares for high speed testing. This was fired out of a gas gun where peak acceleration was up to 10,000g. It was actually pretty easy. Just lay all the components flat and spray a solidifying film over it all. Components that are soft and squishy like electrolytic capacitors were avoided. However, the electronics do need to be potted and the spacecraft walls need to be quite thick. The only problem we had was when we tried to use Li-Po batteries. The batteries were oriented vertically which we believed were causing shorts when the projectile was fired, causing the electronics to briefly fail and not complete their tasks like firing the flares and parachute to recover the projectile. However, horizontal orientation may not be a problem, as indicated by the mobile phone tests.

Below is the prototype board I designed and built.

[ParabolicSnark]

I've had some experience designing electronics for high g, designing a small board for a reusable projectile that ejected flares for high speed testing. This was fired out of a gas gun where peak acceleration was up to 10,000g. It was actually pretty easy. Just lay all the components flat and spray a solidifying film over it all.

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.
2) While a single board may be doable, the vehicle and payload avionics enclosures may have multiple boards in an enclosure and the only way to support the assembly would be to pot the entire enclosure (heavy and a service nightmare).

[ParabolicSnark]

If the first stage is a liquid rocket, they're going to have to fight the hydrostatic pressure variance across the vehicle during the spin.

This pressure gradient is about 0.4 psi/foot/G for water. LOx is about 12% denser and RP-1 is 20% less dense. Nitrogen tetroxide and hydrazine are in the same ballpark too. Even hydrogen only brings it down to 7% that of water (and that only solves the problem for fuel).

For a 3 ft diameter vehicle, this means that the pressure on the outboard surface of the tank will be 12,000 psi (9,600 psi for RP-1; 13,400 psi for LOx; 17,300 for N2O2; 840 for LH2) higher than the inboard pressure.

That's an immense amount of tank weight that becomes immediately useless after exiting the door. Then there's the issue that fluids do undesirable things at these types of pressures, including LOx auto-igniting most metals.

[ChrisWilson68]

Satellites aren't just a single circuit board.  They also have thrusters, antennas, solar panels, optices, etc.  All of those things will need radical redesign to survive a sustained 10,000g.

And then there's the upper stage.  It also needs to survive a sustained 10,000g of force.  What is that going to do to its mass fraction?  To the cost of its control systems and guidance?  To its reliability?

I think it's possible to make an upper stage that will survive that.  But you'll end up with a very expensive upper stage.  Just like the 10,000 g requirement makes your satellites very expensive.

[jongoff]

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.

Couple of points -- first the build-up to the 10,000G+ radial component is very gradual (over the course of over an hour), which is actually quite a bit different from a 10,000G shock load.

Second, the deceleration due to air drag is probably nowhere near as high as you think. The force of drag equals Fd= 1/2 * rho * Cd * A * V^2, but the acceleration due to drag divides that by the mass of the vehicle. Just guessing based off of the sizes of things I've seen in pictures and mockups, etc. Say their vehicle is 1m diameter, and very aerodynamically optimized (say a Cd of 0.1), and say about 5000kg mass. Rho at sea level is around 1.2kg/m^3.

So 0.5 * 1.2 kg/m^3 * 0.1 * pi * (0.5m)^2 * (2300m/s)^2/5000kg = ~49.9 m / s^2, which is only 5G.

Note, this also suggests that the dart only slows down by less than 350m/s by the time it's punched through most of the appreciable atmosphere (in about 7s).

It's kind of impressive what you can do with a high ballistic coefficient m/(Cd*A)...

~Jon

[Lars-J]

Even if that is all resolved But they still need to provide a substantial upper stage, otherwise this is just a suborbital cannon.

Perhaps I missed something but won't the upper stage need to contribute several km/s to reach orbit?

[ChrisWilson68]

Even if that is all resolved But they still need to provide a substantial upper stage, otherwise this is just a suborbital cannon.

Perhaps I missed something but won't the upper stage need to contribute several km/s to reach orbit?

Yes, they mentioned somewhere the delta-v of their launcher and it was only a few km/s, so there's no doubt their upper stage needs to add several more km/s to reach orbit.

[Comga]

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.

Couple of points -- first the build-up to the 10,000G+ radial component is very gradual (over the course of over an hour), which is actually quite a bit different from a 10,000G shock load.

Second, the deceleration due to air drag is probably nowhere near as high as you think. The force of drag equals Fd= 1/2 * rho * Cd * A * V^2, but the acceleration due to drag divides that by the mass of the vehicle. Just guessing based off of the sizes of things I've seen in pictures and mockups, etc. Say their vehicle is 1m diameter, and very aerodynamically optimized (say a Cd of 0.1), and say about 5000kg mass. Rho at sea level is around 1.2kg/m^3.

So 0.5 * 1.2 kg/m^3 * 0.1 * pi * (0.5m)^2 * (2300m/s)^2/5000kg = ~49.9 m / s^2, which is only 5G.

Note, this also suggests that the dart only slows down by less than 350m/s by the time it's punched through most of the appreciable atmosphere (in about 7s).

It's kind of impressive what you can do with a high ballistic coefficient m/(Cd*A)...

~Jon

Is that equation, or those constants, valid for supersonic and hypersonic velocities?
There are many sources on the web, including one from NASA Glenn Research Center. 
It has equations for changes in these parameters including the effective density, which they show to be a function of Mach number, "specific heat ratio", and "wedge angle" of the projectile/vehicle.
It would seem that the drag would be much greater than what is predicted by an extrapolation of that subsonic equation.

[edzieba]

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.

Couple of points -- first the build-up to the 10,000G+ radial component is very gradual (over the course of over an hour), which is actually quite a bit different from a 10,000G shock load.

Second, the deceleration due to air drag is probably nowhere near as high as you think. The force of drag equals Fd= 1/2 * rho * Cd * A * V^2, but the acceleration due to drag divides that by the mass of the vehicle. Just guessing based off of the sizes of things I've seen in pictures and mockups, etc. Say their vehicle is 1m diameter, and very aerodynamically optimized (say a Cd of 0.1), and say about 5000kg mass. Rho at sea level is around 1.2kg/m^3.

So 0.5 * 1.2 kg/m^3 * 0.1 * pi * (0.5m)^2 * (2300m/s)^2/5000kg = ~49.9 m / s^2, which is only 5G.

Note, this also suggests that the dart only slows down by less than 350m/s by the time it's punched through most of the appreciable atmosphere (in about 7s).

It's kind of impressive what you can do with a high ballistic coefficient m/(Cd*A)...

~Jon

Is that equation, or those constants, valid for supersonic and hypersonic velocities?
There are many sources on the web, including one from NASA Glenn Research Center. 
It has equations for changes in these parameters including the effective density, which they show to be a function of Mach number, "specific heat ratio", and "wedge angle" of the projectile/vehicle.
It would seem that the drag would be much greater than what is predicted by an extrapolation of that subsonic equation.

Looks pretty close. For HARP's Martlets, they lost ~250m/s to atmosphere when fired straight up (starting from ~2.1km/s), so an extra ~100m/s on top of that when firing at a slant is not unreasonable.

[Comga]

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.

Couple of points -- first the build-up to the 10,000G+ radial component is very gradual (over the course of over an hour), which is actually quite a bit different from a 10,000G shock load.

Second, the deceleration due to air drag is probably nowhere near as high as you think. The force of drag equals Fd= 1/2 * rho * Cd * A * V^2, but the acceleration due to drag divides that by the mass of the vehicle. Just guessing based off of the sizes of things I've seen in pictures and mockups, etc. Say their vehicle is 1m diameter, and very aerodynamically optimized (say a Cd of 0.1), and say about 5000kg mass. Rho at sea level is around 1.2kg/m^3.

So 0.5 * 1.2 kg/m^3 * 0.1 * pi * (0.5m)^2 * (2300m/s)^2/5000kg = ~49.9 m / s^2, which is only 5G.

Note, this also suggests that the dart only slows down by less than 350m/s by the time it's punched through most of the appreciable atmosphere (in about 7s).

It's kind of impressive what you can do with a high ballistic coefficient m/(Cd*A)...

~Jon

Is that equation, or those constants, valid for supersonic and hypersonic velocities?
There are many sources on the web, including one from NASA Glenn Research Center. 
It has equations for changes in these parameters including the effective density, which they show to be a function of Mach number, "specific heat ratio", and "wedge angle" of the projectile/vehicle.
It would seem that the drag would be much greater than what is predicted by an extrapolation of that subsonic equation.

Looks pretty close. For HARP's Martlets, they lost ~250m/s to atmosphere when fired straight up (starting from ~2.1km/s), so an extra ~100m/s on top of that when firing at a slant is not unreasonable.

But V-squared from 2.1 km/sec to ~8 km/sec is a factor of ~15.
That's much bigger than the secant effect, which itself is going to be large when launching closer to horizontally.
The validity of the extrapolation is more than questionable.

[jongoff]

Even if that is all resolved But they still need to provide a substantial upper stage, otherwise this is just a suborbital cannon.

Perhaps I missed something but won't the upper stage need to contribute several km/s to reach orbit?

Yeah, probably around 6km/s of required rocket dV. This is why while I think their system will actually work, I'm skeptical that it will be cheap enough to get large numbers of customers to switch to them.

~Jon

[jongoff]

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.

Couple of points -- first the build-up to the 10,000G+ radial component is very gradual (over the course of over an hour), which is actually quite a bit different from a 10,000G shock load.

Second, the deceleration due to air drag is probably nowhere near as high as you think. The force of drag equals Fd= 1/2 * rho * Cd * A * V^2, but the acceleration due to drag divides that by the mass of the vehicle. Just guessing based off of the sizes of things I've seen in pictures and mockups, etc. Say their vehicle is 1m diameter, and very aerodynamically optimized (say a Cd of 0.1), and say about 5000kg mass. Rho at sea level is around 1.2kg/m^3.

So 0.5 * 1.2 kg/m^3 * 0.1 * pi * (0.5m)^2 * (2300m/s)^2/5000kg = ~49.9 m / s^2, which is only 5G.

Note, this also suggests that the dart only slows down by less than 350m/s by the time it's punched through most of the appreciable atmosphere (in about 7s).

It's kind of impressive what you can do with a high ballistic coefficient m/(Cd*A)...

~Jon

Is that equation, or those constants, valid for supersonic and hypersonic velocities?
There are many sources on the web, including one from NASA Glenn Research Center. 
It has equations for changes in these parameters including the effective density, which they show to be a function of Mach number, "specific heat ratio", and "wedge angle" of the projectile/vehicle.
It would seem that the drag would be much greater than what is predicted by an extrapolation of that subsonic equation.

You just have the Cd be a function of Mach number. I looked at a bunch of bullets (which are probably worse aerodynamically than this dart), and they peaked at around 0.2 Cd at around Mach 2, with the Cd dropping asymptotically back to a number around 0.1. Even if I'm off by a factor of 2x, that's still only 10G of decelleration, which is three orders of magnitude less than the radial acceleration. My point was just that you're not taking insane accelerations in two axes, just one.

~Jon

[jongoff]

Great contribution and insight. I think the individual boards and circuitry would be as you describe; but I see two key differences:
1) During the spin up, the acceleration vector is radially oriented. After release, the shock and deceleration is in the axial direction. They're mutually exclusive. Support the radial 10,000 G's and then the shock shears them off the board.

Couple of points -- first the build-up to the 10,000G+ radial component is very gradual (over the course of over an hour), which is actually quite a bit different from a 10,000G shock load.

Second, the deceleration due to air drag is probably nowhere near as high as you think. The force of drag equals Fd= 1/2 * rho * Cd * A * V^2, but the acceleration due to drag divides that by the mass of the vehicle. Just guessing based off of the sizes of things I've seen in pictures and mockups, etc. Say their vehicle is 1m diameter, and very aerodynamically optimized (say a Cd of 0.1), and say about 5000kg mass. Rho at sea level is around 1.2kg/m^3.

So 0.5 * 1.2 kg/m^3 * 0.1 * pi * (0.5m)^2 * (2300m/s)^2/5000kg = ~49.9 m / s^2, which is only 5G.

Note, this also suggests that the dart only slows down by less than 350m/s by the time it's punched through most of the appreciable atmosphere (in about 7s).

It's kind of impressive what you can do with a high ballistic coefficient m/(Cd*A)...

~Jon

Is that equation, or those constants, valid for supersonic and hypersonic velocities?
There are many sources on the web, including one from NASA Glenn Research Center. 
It has equations for changes in these parameters including the effective density, which they show to be a function of Mach number, "specific heat ratio", and "wedge angle" of the projectile/vehicle.
It would seem that the drag would be much greater than what is predicted by an extrapolation of that subsonic equation.

Looks pretty close. For HARP's Martlets, they lost ~250m/s to atmosphere when fired straight up (starting from ~2.1km/s), so an extra ~100m/s on top of that when firing at a slant is not unreasonable.

But V-squared from 2.1 km/sec to ~8 km/sec is a factor of ~15.
That's much bigger than the secant effect, which itself is going to be large when launching closer to horizontally.
The validity of the extrapolation is more than questionable.

They're not going 8km/s coming out of the spin launch chamber -- only a little north of 2km/s (as per the article). Pretty similar to the HARP launches. They're using the spin launch as a very reusable first stage.

~Jon

[PM3]

December 15, 2020:

SpinLaunch to expand at Spaceport America

California-based SpinLaunch Inc. is expanding its operations at Spaceport America in southern New Mexico, where it plans to test new technology to literally fling rockets into space.

The company already built a $7 million, 10,000-square-foot facility at the Spaceport after announcing plans last year to conduct all testing there on its new technology. Now, the company is doubling down, with plans to hire an additional 59 people and invest another $46 million over 10 years.

The state Economic Development Department will support the expansion with $4 million in Local Economic Development Act funding, said EDD Secretary Alicia J. Keyes.

https://www.abqjournal.com/1527122/latest-business-news-134.html

SpinLaunch Locates Mass Accelerator at New Mexico’s Spaceport America

...
According to New Mexico Cabinet Secretary Alicia J. Keyes, SpinLaunch signed a lease at Spaceport America in 2019 and has since invested in test facilities and an integration facility. The company is now set to hire an additional 59 highly-paid workers and complete the build of its suborbital centrifugal launch system for its next phase of development. SpinLaunch expects to start test launches in New Mexico in 2021.

https://www.areadevelopment.com/newsItems/12-17-2020/spinlaunch-spaceport-america-new-mexico.shtml

[CameronD]

SpinLaunch to expand at Spaceport America

California-based SpinLaunch Inc. is expanding its operations at Spaceport America in southern New Mexico, where it plans to test new technology to literally fling rockets into space.

The company already built a $7 million, 10,000-square-foot facility at the Spaceport after announcing plans last year to conduct all testing there on its new technology. Now, the company is doubling down, with plans to hire an additional 59 people and invest another $46 million over 10 years.
..............

That's an awfully large investment to spend on tech that doesn't work...? 
 

[Asteroza]

SpinLaunch to expand at Spaceport America

California-based SpinLaunch Inc. is expanding its operations at Spaceport America in southern New Mexico, where it plans to test new technology to literally fling rockets into space.

The company already built a $7 million, 10,000-square-foot facility at the Spaceport after announcing plans last year to conduct all testing there on its new technology. Now, the company is doubling down, with plans to hire an additional 59 people and invest another $46 million over 10 years.
..............

That's an awfully large investment to spend on tech that doesn't work...? 

There's also a lot of dumb VC money flowing through the NewSpace coffers at the moment...

[TrevorMonty]

SpinLaunch to expand at Spaceport America

California-based SpinLaunch Inc. is expanding its operations at Spaceport America in southern New Mexico, where it plans to test new technology to literally fling rockets into space.

The company already built a $7 million, 10,000-square-foot facility at the Spaceport after announcing plans last year to conduct all testing there on its new technology. Now, the company is doubling down, with plans to hire an additional 59 people and invest another $46 million over 10 years.
..............

That's an awfully large investment to spend on tech that doesn't work...? 

I have my doubts about it working for earth launch but should be ideal for moon. Not silly investment but may have to wait for lunar ISRU to be established at end of this decade.


Sent from my SM-T810 using Tapatalk

[edzieba]

SpinLaunch to expand at Spaceport America

California-based SpinLaunch Inc. is expanding its operations at Spaceport America in southern New Mexico, where it plans to test new technology to literally fling rockets into space.

The company already built a $7 million, 10,000-square-foot facility at the Spaceport after announcing plans last year to conduct all testing there on its new technology. Now, the company is doubling down, with plans to hire an additional 59 people and invest another $46 million over 10 years.
..............

That's an awfully large investment to spend on tech that doesn't work...? 

There's a lot to question about the business case (basically needs to have satellites designed to be launched by it due to acceleration environment, payload is small vs. vehicle mass, still requires expendable upper stage), but there are no technical barriers to success in terms of physics - if you fling an object fast enough it will exit the atmosphere at speed - or materials science - it's a MIRV that goes sideways and up rather than sideways and down - or electronics - guided artillery rounds endure harsher accelerations and shocks.

[meekGee]

SpinLaunch to expand at Spaceport America

California-based SpinLaunch Inc. is expanding its operations at Spaceport America in southern New Mexico, where it plans to test new technology to literally fling rockets into space.

The company already built a $7 million, 10,000-square-foot facility at the Spaceport after announcing plans last year to conduct all testing there on its new technology. Now, the company is doubling down, with plans to hire an additional 59 people and invest another $46 million over 10 years.
..............

That's an awfully large investment to spend on tech that doesn't work...? 

There's a lot to question about the business case (basically needs to have satellites designed to be launched by it due to acceleration environment, payload is small vs. vehicle mass, still requires expendable upper stage), but there are no technical barriers to success in terms of physics - if you fling an object fast enough it will exit the atmosphere at speed - or materials science - it's a MIRV that goes sideways and up rather than sideways and down - or electronics - guided artillery rounds endure harsher accelerations and shocks.

There's significant technical challenge in designing a second stage that can survive being shot out at 2 km/sec into still air, and yet have a reasonable mass fraction to achieve orbit with an acceptable payload.

Unlike first stages, second stages care about mass fraction and about ISP. This second stage will need thick walls and probably solid fuel - and still provide 6000+ m/s.

This is more than a business problem.

.. and then of course there's the business problem.

[Robotbeat]

Spinlaunch rests firmly in a part of the trade space where it’s known to be both physically possible but also fundamentally infeasible in the marketplace.

It has no advantage over a conventional rocket.