Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

tahanson43206 · 2023-09-03 14:13:47

GW Johnson asked me to post this video...

https://www.youtube.com/watch?v=csFyhYSLwic

This is a very recent update on the Spin Launch system.

Other items from the email:

Their sling rig is a vertically-oriented disk-shaped pressure vessel with one tangential outlet pipe vertically upward. That pipe has a pressure door that is open during a run. The vacuum is maintained by a membrane that the projectile bursts through. There is no timing except for release vertically upward, and that is critical. The arm is balanced for the loaded projectile. There is a big electric motor at the hub with its shaft through a shaft seal that spins the arm (I believe I heard) at 1200 rpm. It's a big arm. The attached jpg photo is from the CBS News video story about this , 0:8:16 long, titled "New Tech Puts A New Spin On Space Travel", dated 2 Sept 2023. The reporter was Jeff Glor. It's in their "technology" section. If there was some sort of link, I am not able to find it.
GW

(th)

GW Johnson · 2023-09-04 09:37:55

I watched the story again and verified the 1200 rpm value. The story gave an approximate "muzzle velocity" of 5000 mph vertically upward, with an apogee altitude "somewhat over 40 miles", presumed to be statute miles (the 5280-foot miles).

Compare that with the conditions for Spaceship Two, Mach 3 (about 2000 mph) at about 45-50,000 feet, apogeeing just above 50 statute miles. The different is the extra drag lower in the atmosphere at the sharply higher speed, and the effects of about 45-50,000 feet worth of extra potential energy to overcome from the surface launch.

1200 rpm is 20 revs per second, which is 125.7 radians per second. Judging from the photography, the radius arm is roughly 75 feet long. Tip speed would be radius x rad/s = 9428 ft/sec = 6428 mph. Not too far off. Using 5000 mph = 7333 ft/sec, and 125.7 rad/sec, the arm radius is 58 feet. Just for giggles, call it 60 feet = 18.3 m.

Now, centrifugal acceleration value is radius x (rad/sec)^2. So at 60 feet and 1200 rpm, the acceleration is 60 feet * (125.7 rad/sec)^2 = 948,000 ft/sec^2 = about 29,500 standard gees.

The payload must be VERY hard to withstand that!

Using approximate high school physics kinematics, at 5000 mph vertical launch, the average velocity (zero at apogee by definition) is 2500 mph. Distance divided by velocity is an estimate of time to apogee from launch = 0.016 hour = 57 seconds. I thought I heard the story say "30-some seconds". That's not as close as I would like to see it.

But it is in the ballpark.

GW

Last edited by GW Johnson (2023-09-04 09:41:02)

tahanson43206 · 2023-09-04 11:10:27

For GW Johnson re #27

Thank you for your analysis of the Spin Launch concept and reported performance.

This is just a guess on my part, but the rate of reduction of velocity ** may ** NOT be linear over the course of the ascent, which may account for the 30 second figure reported in the article. The rate of reduction of velocity due to drag would (presumably) diminish as the projectile ascends. Reduction in the force of gravity is also going on, but I am guessing that amount of reduction over a mere 40 miles is insignificant.

There are two possibilities (from my perspective).... the figures reported by the reporter may be fudge figures provided by the company, or they may be correct.

Is it possible to take the altitude and the time as correct, and work backward from there?

To achieve the 30 second time, it seems to me (based upon your analysis) that the launch velocity must be greater than 5000 mph.

Air drag would reduce the launch velocity in combination with the pull of gravity, but the rate of loss would NOT be linear. On the other hand, I would imagine there are figures on drag of the atmosphere at various altitudes accumulated over a century or more of flight, so perhaps there is a way to estimate the drag at various altitudes with some accuracy.

In any case, if you are inspired to tackle another round of analysis, the results ** should ** be interesting!

We have a limited supply of aerospace engineers in this forum, but we certainly can add more. See the Recruiting Topic if you are a visiting reader of the forum, and would like to assist with this topic (or any serious topic).

(th)

Calliban · 2023-10-02 08:33:34

A compact spinlaunch device could be very useful for exporting bulk ores from the surface of the moon for use in space manufacturing. The escape velocity of the moon is 2380m/s. A spin launcher with an arm radius of 1m, would need to achieve 22,727 revs in order to reach that linear speed. We have gas turbine engines that operate in that range, suggesting that this would be an achievable near term option.

The exported lunar material would need to be either housed in a robust container to withstand the force of acceleration, or sintered in solid slugs. A magazine system woukd be needed to load the slugs into the rotating machine.

The advantage this has over a conventional mass driver is relative compactness. A mass driver is usually expected to be hundreds of metres long. The spin launcher can be driven by a frequency controlled AC motor. At these speeds, I think gearing would be impractical. Some sort of vacuum rated lubricant would be needed to lubricate and cool the bearings. I think lead can be ruled out for this application.

Last edited by Calliban (2023-10-02 08:49:56)

tahanson43206 · 2023-10-02 10:26:40

For Calliban re #29

It is good to see your post on adapting SpinLaunch to the Moon.

If you have time, and the question is of interest, please perform a similar analysis for Mars.

It seems to me that shipments of propellant to Phobos would be most welcome, for both arriving vessels, departing ones, and ferries plying the Phobos/Mars trade.

***
Regarding bearings. I suspect you have not yet had time to study the working SpinLaunch facility. The bearings are safely enclosed, and I would expect the company will use the same enclosure on the Moon and Mars, and where-ever else similar facilities are needed.

There is a question of IP protection. It is possible that SpinLaunch did not think to protect their IP for use off planet. That would be an oversight, so I'll write to them to ask.

It would be far easier to license their technology for a company that ships product from the Moon and Mars, than to develop a system from scratch.

I'll report correspondence, if any.

(th)

tahanson43206 · 2023-10-02 10:34:11

This is a follow up to the previous post to Calliban:

I serve as a (Junior) moderator for the NewMars.com forum of the Mars Society. A member has inquired about the suitability of your system for use on the Moon or Mars. His analysis supports the conclusion that your system is superior to linear launch systems for regolith or refined product. My concern is that you may not have included off-Earth protection in your legal coverage for your IP. Please reply with the specific language in your patent claims that covers off-Earth use. This would be the starting point for an inquiry about licensing. Thanks tahanson43206

(th)

Mars_B4_Moon · 2023-11-01 04:09:47

SpinLaunch announces new leadership roles

https://www.spacedaily.com/reports/Spin … s_999.html

SpaceNut · 2024-01-26 17:17:26

This Revolutionary Launch System Sends Satellites Into Orbit Using Electricity

BB1h370f.img?w=768&h=431&m=6

tahanson43206 · 2024-01-26 18:24:55

For SpaceNut re #33

Thanks for the image, and for the link to the article about SpinLaunch...

The article has a link to the original article: here is the credit:

BY DAVID ROSSIAKY/JAN. 21, 2024 10:15 PM EST

The article includes a nice reprise of the project HARP research, many years ago.

(th)

tahanson43206 · 2024-04-03 11:19:59

In another topic, Void has introduced the idea of using the spin launch concept to give humans the velocity needed to perform space flight maneuvers.

I am approaching this idea with the expectation it has merit.

Over the years, I have observed that ideas presented by Void often are the nucleus of systems that can perform useful service.

The outstanding example is Void's imagining of a space craft dropping off material to be landed on Mars, before executing the retrorocket procedure to land the space craft itself.

This idea evolved into what looks like a practical business plan for competitive shipping of materials that can withstand high G forces.

There are many materials that can survive momentary high G forces, so the chances an industry will develop around this theme seem high to me.

This post is about the opposite idea ... launching objects, (and especially humans) for space travel, using rotation as the source of velocity.

It seems to me quite practical to consider using this technology for travel between space craft, or between a space craft and a space station.

The alternative is to expend precious mass to accelerate the object (or the human) at each end.

We have an opportunity for our members who are gifted with math and engineering skills to tackle the idea Void has offered, and see what can be done with it.

(th)

Void · 2024-04-03 11:33:14

I am glad that you have an interest in this.

The Spin launch notion can be divided into two categories that I am currently aware of:
1) Spin Unhook Launch (This is like what is done with the concept we are aware of).
2) Spin Slide Launch

#1 may be most suitable for non-human payloads.
#2 may be suitable for human launches.

For #2, imagine that a flywheel device consisting or a power plant, has developed spin inertia that can be tapped.
Now your ship lands at the hub of the spin and begins to launch down a slide track. As it moves outward to greater circumferences of spin, the ship is given inertia from the spinning launch platform. If the timing is correct the ship can be flung to a higher or lower orbit than the platform has.

The spin release could be additive to the orbit of the platform, or subtractive to the spin of the platform.

So, far I have considered that electric rocket propulsion would impart the spin energy on the spin platform.

By the way I have seen the spin-slide concept in someone's patent. That's a good thing as the idea may be valid for some situations of needs and desires in space.

While nuclear is possible as the power plant, solar may be well suited to power the spinning platform. One thing not liked about using solar with electric rockets to go to Mars, is the inertia of the power plant, and the fact that the sunlight diminishes as you travel away from the sun.

But with this the solar power plant stays near Earth, in the case that Earth is the place of departure, and its weight becomes an advantage as the inertia of the spinning solar panels, is part of a flywheel. Then if you release the load, the solar panels stay in an Earth orbit.

The slide action may reduce the amount of g forces experienced inside the ship, I don't have good calculations for that, as there can be so many instances of types of structure for spin launch platforms. It is silly to try yet. You might make a crude estimate to sort of start to understand what a practical spin platform might be like.

My current understanding for the tolerable g force for humans might be at about 4g for a launch situation. I think trained and exceptional people might tolerate up to 10g for a short duration of time.

But perhaps that needs corrections.

Done

It is possible that some type of simultaneous propulsion method might be added to this. For instance, a mechanical catapult that would start the ship away from the hub and down the slide track. Even a mass driver, system but I think that would be complex, probably more complicated than might be desired. We might look into a "Sling" process.

Sling: https://en.wikipedia.org/wiki/Sling_(weapon)

Catapult: https://en.wikipedia.org/wiki/Catapult

Onager: https://en.wikipedia.org/wiki/Onager_(weapon)
Quote:

The onager (British /ˈɒnədʒə/, /ˈɒnəɡə/, U.S. /ˈɑnədʒər/)[1] was a Roman torsion powered siege engine. It is commonly depicted as a catapult with a bowl, bucket, or sling at the end of its throwing arm.

Done

Last edited by Void (2024-04-03 11:54:19)

GW Johnson · 2024-04-03 16:06:16

If I understand what you mean by spin-slide, there are radial accelerations that are calculated as a = R w^2, where w is the spin rate, and there are Coriolis accelerations that I don't remember how to calculate, but which do depend in part on the product of speed V and spin rate w. The Coriolis accelerations are parallel to the periphery, or perpendicular to the radial. Both exist at the same time, and add vectorially.

Be aware that the human body starts coming apart when subjected to just about 40-45 gees of acceleration. Posture and support do not mitigate that limit. It is why many fighter pilots say that using an ejection seat (at 30-40 gees) is committing suicide to keep from getting killed.

I rather doubt that there is a solution space for rw^2 and Vw under 40 gees, with the tip velocity V = Rw being of orbital class, unless R is thousands of km. Therefore, I don't believe there will ever be any kind of spin launch for humans.

GW

Void · 2024-04-03 21:01:34

Your advice is valuable.

This that I spoke of is not to launch from the Earth, but rather to be in orbit of a world already, and so then it is only a booster for a ship.
Granted it could be used for human occupied craft, I included that potential, but as you have indicated it might really do well to push loads at extreme g forces.

It is to be spun up with electric rocket propulsion for instance. Then a load may be put onto the rotational hub, and then a pusher or catapult can start it down the slide.

I know that the previous device mentioned was to launch loads from Earth, but that is not what this would be.

Done

New Mars Forums

Announcement

#26 2023-09-03 14:13:47

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#27 2023-09-04 09:37:55

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#28 2023-09-04 11:10:27

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#29 2023-10-02 08:33:34

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#30 2023-10-02 10:26:40

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#31 2023-10-02 10:34:11

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#32 2023-11-01 04:09:47

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#33 2024-01-26 17:17:26

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#34 2024-01-26 18:24:55

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#35 2024-04-03 11:19:59

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#36 2024-04-03 11:33:14

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#37 2024-04-03 16:06:16

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

#38 2024-04-03 21:01:34

Re: Spin Launch SpinLaunch Vacuum Launches Centrifuge Launched Mass

Board footer