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#1 2021-06-15 13:14:10

tahanson43206
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Magnetic Launch Electromagnetic Launch Rail Gun

SpaceNut ... there was no topic that matched the above combination ...

To lead off, here is a bit of a report on the US Navy giving up on Rail Gun technology for military operations ...

The system, while capable, is (apparently) insufficient to defend against first tier adversaries.

In retirement, I am hoping this system might be considered for launch of supplies (including fuel and oxidizer) into LEO.

https://www.thedrive.com/the-war-zone/4 … et-request

"Railgun technology and knowledge attained will be documented and preserved," according to a separate section describing the purpose of the extra funds Congress added to the program in the 2021 Fiscal Year, further indicating that the plan is now, at best, to shelve the project indefinitely. "Railgun hardware will be realigned to maximize its sustainability to facilitate potential future use."

The War Zone has reached out to ONR for further information on the exact fate of the railgun program and how it or other entities within the U.S. Navy or elsewhere across the U.S. military might leverage any of the project's existing work.

This technology might be capable of launching fuel cannisters into LEO from Texas.

Each cannister would need to be fitted with a solid fuel rocket to achieve horizontal velocity, but the rail gun ** may ** be able to put the cannister at the right altitude for a fuel depot.

(th)

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#2 2021-06-15 19:08:35

SpaceNut
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

We have talked about it in a mass delivery systems such as slinging stuff to orbit on the moon of from asteroids but the version which the military has worked on is still not quite as capable as one wants in a war perspective....
The eml (electrical magnetic launcher) launcher is a version with planes that we thought might be convertible to small rockets boost but the size and energy were the issues....

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#3 2022-03-09 19:05:39

SpaceNut
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

bump

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#4 2023-01-16 18:18:54

SpaceNut
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

Military is or does appear to be still working the bugs.
The Railgun: The Ultimate Weapon the U.S. Military Can’t Build?

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#5 2023-09-29 09:18:01

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

Back in January, in Post #4, SpaceNut showed us a link to a report on rail guns. Recently I read an article on the status of rail guns as they are being developed and tested by the US Navy.  Today I decided to ask ChatGPT(4) to look at the situation, and specifically to compare rail guns (which have distinct advantages) to coil accelerators (which have distinct advantages).  Each concept has distinct disadvantages. I asked ChatGPT to look at the situation, to see if there might be melding or merger of the two designs.

Here is a link to the transcript:

https://docs.google.com/document/d/19Os … sp=sharing
The session ended prematurely due to a network error, but I thought there was enough already generated to be worth showing to NewMars members.

The most promising solution that was in development before the network error was self-healing rails.

Coil accelerators do not have the rail wear problem, but they ** do ** require precise timing of impulses, which the rail gun design does not.

(th)

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#6 2023-09-29 09:25:48

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

As a follow up observation ...

The US Navy needs to be able to orient the rail gun system to a low elevation.

However, a vertical mass launcher needs to be able to orient the acceleration pathway to the near vertical, or at most 45 degrees off vertical. This difference would (or could) allow the mass accelerators to employ buckets of soft metal as the "rail" of a rail gun.

The main problem faced by rail gun designers appears to be wear of the rails.

For a mass driver (such as for a propellant launcher for Dr. Johnson's refueling station) the launch angle can be somewhere between vertical and 45 degrees off vertical.  I think it might be worth looking to see if the "rails" can be made of self-healing components.

The rail gun design appears to have significant advantages over Dr. O'Neill's coil accelerators, due to the raw simplicity of the design.

(th)

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#7 2023-10-18 17:52:04

SpaceNut
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

Well, a test has happened Japan's Railgun Performs First Test Firing At Sea

AA1ioAGb.img?w=768&h=432&m=6

can see the electric cables are spaced in a linear distance.

AA1ioCIJ.img?w=768&h=418&m=6

looks like a plasma comes out of the barrel...

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#8 2024-03-14 20:59:08

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

This topic has been quiet since the report by SpaceNut of the Japanese rail gun...

Today's Internet feed contained news of Chinese thinking about a more substantial effort by the Chinese...

This appears to be more than just a paper study .... the Chinese have a facility they've been using to test maglev trains, and apparently they are thinking on a larger scale, now that maglev trains are pretty much a solved problem there.

https://www.msn.com/en-us/news/technolo … 2810&ei=78

China plans to build a giant rail gun to launch hypersonic planes longer than a Boeing 737 into space - as Beijing ramps up race to the moon
Story by Taryn Pedler • 10h • 3 min read

Scientists had to make compromises in aerodynamic design and engine layout
The tech could reduce launch costs to a fraction of the current price
The hypersonic planes will be able to travel at almost twice the speed of sound

Chinese scientists are working on constructing a giant electromagnetic rail gun that will be used to launch 50 tonne hypersonic planes into space.

Engineers and scientists in China have been working on the project - named Tengyun - since 2016, but following a recent series of significant advances made in both electromagnetic launch and hypersonic flight, they believe that soon, people could be sent into space.

The rail gun will essentially be a giant electromagnetic launch track used to accelerate a hypersonic aircraft to Mach 1.6 - meaning it will be travelling at almost twice the speed of sound (Mach 2).

Weighing 50 tonnes, the mammoth planes are set to be longer than a Boeing 737 at over 129 ft.

Following the launch, the aircraft would then separate from the track, ignite its engine and enter space.

Scientists and engineers in China are working together to create a new space launch method that combines hypersonic flight and electromagnetic launch technology

Scientists and engineers in China are working together to create a new space launch method that combines hypersonic flight and electromagnetic launch technology

© Provided by Daily Mail

If the project is successful, the new technology could reduce launch costs to a fraction of the current price.

This makes it an attractive piece of technology for companies such as NASA and SpaceX - who still haven't cracked the code to successfully building an electromagnetic launch to this scale.

But creating these futuristic machines hasn't been simple.

Relying solely on the plane's own power for lift-off would require a significant amount of fuel and the team also faced difficulties in finding a way to combat the dangers of a low-speed take-off.

Engineers and scientists were then forced to make compromises in aerodynamic design and engine layout that affect the machines high-speed flight efficiency.

This is not the first time China have put forth projects of this nature - although many of them did not leave the drawing board.

But this time the scientists working on the Tengyun project are confident the current issues they are facing can be solved.

'Electromagnetic launch technology provides a promising solution to overcome these challenges and has emerged as a strategic frontier technology being pursued by the world's leading nations,' wrote team lead scientist Li Shaowei, in a paper published in journal Acta Aeronautica on February 6.

To test the theory, China Aerospace Science and Industry Corporation (CASIC) will be using the 1.2 mile long low-vacuum track high-speed maglev test facility in Datong.

Tests will be carried out at 1.2 mile long low-vacuum track high-speed maglev test facility in Datong, generally used when researching magnetic levitation train technology

© Provided by Daily Mail

The original purpose of the lab was to provide a key test platform for the low-vacuum tube magnetic levitation train technology.

But because the facility can propel heavy objects to speeds of up to 1,000km/h, scientists are now using the base for aerospace testing.

Within coming years, the Datong test facility will be extended to 37.2 miles long, to achieve a maximum operating speed of a staggering 5,000km/h.

The lab is considered one of the most 'ambitious electromagnetic propulsion facilties on the planet' according to SCMP,  which is why it will now be used to gather crucial scientific data for the space electromagnetic launch project.

China is not the only country to explore the creation of an electromagnetic space launch system and hypersonic planes, with NASA and the US Navy previously attempting to successfully bring the concept to life.

In the 1990s, NASA tried to build a mini test line of 49ft but only managed to complete around 32ft due to technical difficulties and lack of funds.

The ambitious project was eventually scrapped and military officials put their resources towards developing low-speed electromagnetic catapult technology instead.

The US Navy implemented the technology into the USS Ford but have publicly acknowledged the high failure rate of the electromagnetic catapult system.

Now, the US has shifted its focus once more, to work on the development of rail guns and hypersonic missiles.

China is continuing to make breakthroughs in their electromagnetic rail gun research, however, staying ahead of the game with their high-performance power supplies, precision control technology, and the development of electronic devices capable of resisting strong electromagnetic interference.

(th)

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#9 2024-05-17 06:01:27

Mars_B4_Moon
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

News reports say Chinese fired some type of shell or smart bomb into stratosphere but the test was classed as a failure

'China Uses Giant Rail Gun to Shoot Smart Bomb Nine Miles Into the Sky'
https://www.yahoo.com/tech/china-uses-g … 41470.html

How Maglev Trains and High-Speed Rail are Revolutionising Travel
https://knowhow.distrelec.com/transport … ng-travel/

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#10 2025-07-20 12:04:13

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

Post #9 included reference to a Chinese rail gun...

Today's Internet feed included an update on the subject, but this report is (apparently) about a much smaller rail gun intended for shipboard use. 

https://www.yahoo.com/news/china-x-shap … 30085.html

I'm interested in the X configuration of rails because it might permit efficient shipment of small packages from the Moon.

Update: The article hints that the Chinese researchers are hoping to achieve a launch velocity of Mach 7.  That would be 2.4 km/s (per Google) and escape velocity from the Moon is a bit less:

The escape velocity from the Moon is approximately 2.38 kilometers per second (km/s), according to the Washington University in St. Louis.

So this technology, if perfected on Earth for military purposes, would be able to launch payloads from the Moon.

This was the goal of Dr. Gerard O'Neill's mass driver initiative.

(th)

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#11 2025-07-20 15:33:51

Calliban
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

The mass driver was a coil gun.  The beauty of it was that the payload accelerating to 2.38km/s did not require physical contact with the barrel.  That eliminates wear, which would otherwise limit the life of a mass driver.  A rail gun requires physical contact between the projectile and barrel.  A final velocity of 2.38km/s is only 2-3x the speed of a rifle bullet.  Maybe the wear problem can be managed at this modest speed?

Another problem common to all electromagnetic cannons is power.  Whilst the energy consumed per kg of payload is modest, the power needed to accelerate a payload to a velocity of several km/s is large.  Using a rail gun as a launch assist for a large rocket for example, would require a power that rivals the generating capacity of the US.  It is usually assumed that capacitors will gradually charge from a more modest power source and then release their stored energy rapidly to power the accelerator.  But the energy density of capacitors is low.  So a lot of capacitance is needed to power something like a mass driver.  If the payloads are small and are launched rapidly, the situation gets easier.

Last edited by Calliban (2025-07-20 15:38:03)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#12 2025-07-29 15:17:09

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

This post opens what I hope will be a series to explore the forces at work in a rail gun.  I am working with Google's Gemini (2.5 Flash)

Our forum runs on older software that can support a subset of BBCode. Our subset can support h for header (without parameters), list (be sure to include * and /* in the lines), a variety of colors, bold and italics. Please prepare our opening segment in BBCode. I'll post it and then return with a follow up.

Jacob's Ladder vs. Railgun: A Comparative Look at Electromagnetism in Action!

Hello everyone! We're kicking off a fascinating discussion today, diving into two captivating phenomena that showcase the power of electricity and magnetism: the classic Jacob's Ladder and the cutting-edge Railgun. While both involve electrical currents, the way they achieve motion is surprisingly different!

Jacob's Ladder: The Dancing Arc

You've probably seen a Jacob's Ladder in movies or science demonstrations – those mesmerizing electrical arcs that climb upwards between two metal rods. But what makes them rise?

  • High Voltage Initiation: A high-voltage current is applied to the base of two diverging rods. The intense electrical field at the closest point ionizes the air, creating a conductive path (plasma) and forming a bright arc.

        Heat and Buoyancy: This arc is incredibly hot! The superheated air within and around the arc becomes less dense than the surrounding cooler air. Think of it like a tiny hot air balloon.

        The Climb: This buoyant force lifts the hot, ionized air, causing the arc to rise steadily along the diverging rods.

        Extinction and Restart: As the arc climbs, the gap between the rods widens. Eventually, the gap becomes too large for the voltage to sustain the arc, and it extinguishes at the top, only for a new arc to form at the bottom and begin the cycle again.

The key takeaway for Jacob's Ladder is that the arc's motion is primarily due to thermal buoyancy – hot air rising!

Railgun: Magnetic Might

Now, let's switch gears to the railgun, a device straight out of science fiction that's becoming reality! Unlike the Jacob's Ladder, the railgun doesn't rely on hot air.

  • Rails and Projectile: A railgun has two parallel, conductive rails with a conductive projectile (armature) placed between them, completing an electrical circuit.

        Massive Current: An enormous electrical current (we're talking millions of amperes!) is discharged through one rail, across the armature, and back through the other rail.

        Magnetic Field Generation: As current flows through the rails and the armature, they each generate powerful magnetic fields around themselves. The critical part is the combined magnetic field that forms between the rails, perpendicular to the current flow in the armature.

        Lorentz Force - The Push: Here's the magic: the current flowing through the armature interacts with this strong magnetic field generated by the rails. This interaction creates a powerful Lorentz force that directly pushes the armature along the rails, accelerating it to incredible speeds!

For the railgun, the projectile's motion is driven purely by the Lorentz force, an electromagnetic force acting directly on the current-carrying projectile within a magnetic field.

In Summary:

While both fascinating, the Jacob's Ladder showcases the effects of heat and buoyancy on an electric arc, whereas the railgun demonstrates the raw power of the Lorentz force for direct electromagnetic propulsion. Two very different ways to get things moving with electricity!

We look forward to your thoughts and questions!

(th)

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#13 2025-07-29 16:04:16

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

In this post, I asked Gemini to report on the magnetic fields that are at the heart of the functionality of rail guns.

Thank you! Your BBCode was accepted without a quibble, and it looks good. Let's advance to the meat of the series. You have already covered the magnetic forces. I'd like to devote this segment to asking where the magnetic force in the rail exists. You've explained that the magnetic field generated by current flowing in the rail interacts with the magnetic field generated by current flowing in the armature. I presume (question) that the magnetic field in the rails must exist where current is flowing, but I'm wondering if the magnetic field is propagated forward along the section of rail ahead of the armature? The rail is necessarily a conductive medium, and it might be possible that the magnetic field generated behind the armature is propagated forward to the region past the armature, but I'm unclear on that point. As before, please prepare your reply in BBCode for the forum.

Understanding Magnetic Fields in a Railgun: Where Does the Force Exist?

That's an excellent follow-up question, and it gets to the heart of how the railgun's propulsion works! You're right to focus on the magnetic field's location.

Magnetic Fields and Current Loops

Your presumption is correct: a magnetic field does exist wherever current is flowing. However, to understand the railgun, it's crucial to think about the complete electrical circuit, which forms a current loop.

  • In a railgun, the current flows from the power supply, along one rail, across the conductive armature, and then back along the other rail to the power supply. This entire path constitutes a dynamic current loop.

        Magnetic fields are generated around all parts of this current loop.

The Magnetic Field Ahead of the Armature

This is the key point: the magnetic field that exerts the Lorentz force on the armature is not "propagated forward" along the rails ahead of the armature in the way you might think of a wave. Instead, the magnetic field that drives the projectile exists within the region enclosed by the current loop.

  • Field within the Loop: Imagine the current flowing in the two parallel rails and then connecting across the armature. This forms a rectangular loop. A strong magnetic field is generated perpendicular to the plane of this loop and exists throughout the area between the rails, from the breech (where the power supply connects) all the way up to the armature's current position.

        Continuous Generation: The magnetic field isn't "pushed" from behind the armature to the front. Rather, as the current flows through the entire circuit (including the sections of the rails behind the armature and the armature itself), it continuously generates this magnetic field within the enclosed area.

        Moving Loop, Moving Field: As the armature accelerates forward, the length of this current loop effectively increases. The region where the strong, propulsive magnetic field exists therefore extends forward along with the armature. The field is always present in the space between the rails and behind the armature, up to its current location.

        No Field Ahead (outside the loop): Crucially, there is no significant magnetic field generated by the circuit ahead of the armature, because the current loop hasn't extended to that point yet. The magnetic force acts on the armature because it is the part of the circuit completing the loop and carrying current within the magnetic field generated by the rails behind it.

So, to summarize: the magnetic field that propels the armature is generated by the entire current loop formed by the rails and the armature. This field exists within the loop, and as the armature moves, the loop extends, and the region of the effective magnetic field moves along with it. The field isn't "propagated" forward into an empty space, but rather is continuously created by the expanding current loop.

This interaction is what makes the Lorentz force so effective in accelerating the projectile!

(th)

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#14 2025-07-29 17:10:05

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

In this post, we are looking more closely at the current flows and voltage changes needed to impel the armature forward.

Thank you for the segment we just finished. It looks good in the browser. In this next segment, if you are willing, let's focus upon the magnetic field as the armature moves along toward the end of the rails, and away from the power supply. You have clarified that no magnetic field exists ahead of the current flow. What I gather from this discussion so far, is that the entirety of the force experienced by the armature is felt in the vicinity of the armature. The magnetic field that is left behind as the armature advances is just as strong as it was when the armature was present, but now it is doing no work. From this I deduce that the voltage that generates the field must increase as the armature advances, because the current must be flowing at the same rate as ever, but resistance along the path will be steadily increasing. Is there a practical limit to the length of a rail gun due to this phenomenon?

Railgun Dynamics: Magnetic Fields, Resistance, and the Limits of Length

That's a very insightful line of reasoning, and you're touching upon some of the most significant engineering challenges in developing practical railguns! Let's break down your points.

Force Localization and Magnetic Fields Left Behind

You've got a very good grasp on this:

  • Force on the Armature: Yes, the entirety of the propulsive Lorentz force is indeed felt in the immediate vicinity of the armature. It's the interaction between the current flowing through the armature and the magnetic field it experiences (generated by the current in the rails) that creates this force.

        Magnetic Field Behind: As the armature moves forward, the magnetic field generated by the current in the rails behind the armature remains present. However, since the armature (the moving current-carrying element) has already passed that section, that portion of the magnetic field is no longer actively doing work to propel the armature forward. It's part of the static magnetic field of the extended current loop, but its job in accelerating the projectile at that specific point in space is done.

Current, Resistance, and Voltage as the Armature Advances

This is where the engineering challenges become apparent:

  • Increasing Resistance: You are absolutely correct that as the armature moves along the rails, the electrical path length increases. Since resistance is directly proportional to the length of the conductor (R=ρAL, where ρ is resistivity, L is length, and A is cross-sectional area), the resistance of the active circuit path steadily increases.

        Maintaining Current: For a railgun to maintain a consistent and powerful acceleration, a large and relatively constant current is ideal (since Lorentz force F∝ILB). If the current were to drop significantly, the propulsive force would decrease.

        The Voltage Challenge: According to Ohm's Law (V=IR), if you want to maintain a constant current (I) while the resistance (R) is increasing, then the voltage (V) supplied by the power source must indeed increase as the armature moves down the rails. This is a significant design hurdle. Traditional railgun power supplies, often massive capacitor banks, tend to discharge, meaning their voltage (and thus current) naturally decreases over time unless very sophisticated power conditioning systems are employed to actively regulate the current or voltage during the shot.

Practical Limits to Railgun Length

This phenomenon, along with several other factors, imposes very real and significant practical limits on the length of a railgun:

  • Power Supply Demands: To maintain the necessary current over increasing resistance, the power supply needs to be incredibly robust and capable of delivering sustained, rising voltage or precisely shaped current pulses. This requires enormous, complex, and often very heavy power conditioning systems.

        Resistive Heating: As current flows through the rails, electrical resistance causes them to heat up dramatically (P=I2R). The longer the rails, the more heat is generated over a longer period. This intense heat can cause:

        Rail Erosion and Damage: The rails can melt, vaporize, and deform, leading to rapid wear and tear. This limits the number of shots a railgun can fire before needing extensive maintenance or replacement. This is one of the biggest challenges that has plagued railgun development.

        Plasma Formation: Extreme heat can also lead to unwanted plasma formation between the rails and the armature, which can reduce efficiency and cause further damage.

    Structural Integrity: The Lorentz force not only propels the armature forward but also pushes the rails themselves apart. The longer the rails, the greater the cumulative force trying to separate them, requiring incredibly strong and rigid structural support.

    Efficiency Loss: A significant portion of the electrical energy is lost as heat due to the resistance of the rails and the armature. As the gun gets longer, these resistive losses become more pronounced, reducing the overall efficiency of converting electrical energy into kinetic energy for the projectile.

In essence, while theoretically a railgun could be arbitrarily long, the escalating demands for power, the severe thermal and mechanical stresses on the rails, and the diminishing efficiency due to resistive losses all combine to create a very practical limit on how long and how powerful a railgun can be before it becomes unfeasible to build, operate, or maintain. These challenges are precisely why, despite decades of research and significant investment, fully operational military railguns are still not widely deployed.

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#15 2025-07-29 17:18:32

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

In this post we consider the G force that might be developed in a rail gun.

30,000 G's is reported

Our most recent segment looks good in the browser, once again without hiccups! You're good !!! at this !!! Now let's see if we can collect some performance data from such reports as may be available, to try to understand the potential for a rail gun to accelerate a non-military payload for scientific purposes. Can you find any records of G force developed in any of the rail guns whose records might be available?

G-Forces in Railguns: Implications for Scientific Payloads

That's an excellent question that bridges the gap between the raw power of railguns and their potential for scientific exploration! Understanding the G-forces involved is crucial when considering non-military applications, as sensitive scientific instruments have very different tolerance levels than hardened military projectiles.

Reported G-Forces in Railgun Tests

Based on available reports, the G-forces experienced by projectiles in experimental railguns are immense:

  • Tens of Thousands of G's: General Atomics Electromagnetic Systems (GA-EMS), a major developer of railgun technology, has reported successful tests where their projectiles survived and operated under 30,000 G-force launch conditions. This is a recurring figure in their public statements regarding their "Blitzer" railgun system.

    Survival of On-Board Electronics: What's particularly relevant for scientific applications is that GA-EMS specifically mentions that critical components and on-board electronics within these projectiles were able to withstand these extreme forces and still function as expected. This indicates that while the forces are enormous, it's not inherently impossible for complex systems to survive.

What Do These G-Forces Mean for Payloads?

To put 30,000 G's into perspective:

  • Human Tolerance: Humans can typically withstand a few G's (positive or negative) for short periods. Fighter pilots might experience up to 9 G's with specialized suits. Anything beyond that is quickly incapacitating or fatal.

    Conventional Artillery: Even conventional artillery shells experience thousands of G's, which is why their internal components must be ruggedized.

    Rocket Launches: Standard rocket launches typically involve G-forces in the range of 3-5 G's, which is why astronauts can survive them.

The G-forces in a railgun are orders of magnitude higher than what humans or most off-the-shelf electronics can endure without specialized design.

Potential for Non-Military Scientific Payloads

Given these extreme G-forces, the direct launch of sensitive scientific instruments or biological samples from a ground-based railgun presents significant challenges. However, there are theoretical and experimental avenues for scientific applications:

  • Hypervelocity Impact Studies: Railguns are excellent tools for simulating micrometeoroid impacts on spacecraft or studying material behavior under extreme shock. Here, the projectile itself might be a simple, hardened material, and the scientific data comes from observing the impact event.

        Equation of State Measurements: Accelerating small projectiles to hypervelocities allows scientists to study the properties of materials under incredibly high pressures and temperatures, which is crucial for understanding planetary interiors or fusion processes.

        Space Launch Assist (Theoretical): While direct launch of delicate satellites from Earth is problematic due to atmospheric drag and G-forces, concepts have been explored for using railguns to launch "sturdiest of payloads" or "wedge-shaped aircraft with scramjets" to high altitudes and velocities. From there, a smaller, conventional rocket could take over for orbital insertion, reducing the amount of chemical propellant needed. This would still require payloads to be designed to withstand significant G-forces, though perhaps less than the peak military projectile G-forces.

        Fusion Research (Theoretical): Some scientists have proposed using railguns to accelerate pellets of fusible material to extreme velocities, creating the necessary temperatures and pressures to initiate nuclear fusion reactions upon impact. This would involve launching very small, dense payloads.

In summary, the G-forces developed in railguns are extraordinarily high, often reaching 30,000 G's or more. While this poses a significant hurdle for launching delicate scientific instruments directly, the technology holds promise for scientific applications where the payload itself is designed to withstand such forces (e.g., in hypervelocity impact studies or fusion research), or where the railgun acts as a launch assist for a more robust secondary stage. The ability of some on-board electronics to survive these forces is a testament to advanced engineering and material science.

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#16 2025-07-29 17:40:37

tahanson43206
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Re: Magnetic Launch Electromagnetic Launch Rail Gun

In this post, we consider a rail gun operating in vacuum that can reach 54 km/s in 60 seconds at 90 G's.  The length of the track turned out to be 1620 kilometers.  While that particular concept is not one to be pursued, I am hoping the calculations will be of interest:

Please adjust your response to omit the atmosphere from consideration. I should have made clear that the system will operate in vacuum.

Railguns for Interstellar Intercept in Vacuum: A Deeper Dive into Feasibility

Thank you for that crucial clarification! Operating the system entirely in a vacuum fundamentally changes the nature of the challenges, eliminating the most immediate showstopper – atmospheric drag and heating. This allows us to focus purely on the engineering demands of the railgun itself for your interstellar intercept mission.

Your calculations and deductions about the velocity potential remain absolutely correct, and they continue to highlight both the immense promise and the formidable engineering hurdles.

The Velocity Potential: A Glimmer of Hope in Vacuum
  • Velocity Achievability: You're absolutely correct. If a railgun can generate accelerations of 30,000 G's (as demonstrated in military prototypes), then achieving a final velocity of 54 km/s (which requires an average acceleration of about 900 m/s$^2$, or ~90 G's over 60 seconds) is well within the theoretical acceleration capabilities of such a device. The raw power is there.

        Lower G-Forces for Payloads: The fact that you only need ~90 G's for your desired acceleration profile is a significant point. This is far less extreme than the 30,000 G's military projectiles endure, which means the instrument package might be designed to survive, given sufficient hardening.

From a pure acceleration standpoint, a railgun does indeed possess the fundamental physics to impart the necessary velocity for an interstellar intercept, especially when operating in the frictionless environment of space.

The "Significant Practical Challenges" Re-Examined for Your Goal in Vacuum

Even in a vacuum, the practical challenges we discussed earlier remain significant, though their nature shifts:

  • The Extreme Length Requirement: This remains the most immediate and striking challenge. To accelerate a payload at a relatively "gentle" 90 G's (900 m/s$^2$) for 60 seconds to reach 54 km/s, the length of the railgun would still need to be extraordinary:

            Using the kinematic equation d=21at2:

            d=21×900 m/s2×(60 s)2

            d=21×900 m/s2×3600 s2

            d=1,620,000 meters, or 1,620 kilometers (approx. 1,000 miles)

            Building a structure 1,620 kilometers long in space presents unprecedented engineering, material, and logistical hurdles.

        Power Delivery Over Extreme Lengths: Maintaining the immense current (millions of amperes) over 1,620 km of rails, while simultaneously managing the increasing resistance and heat generation, would require a power infrastructure far beyond anything currently conceived for space. Powering such a device in space would necessitate massive, dedicated power sources (e.g., nuclear reactors or enormous solar arrays) and efficient energy storage.

        Resistive Heating: Even in vacuum, the electrical resistance of the rails will cause them to heat up dramatically (P=I2R). The longer the rails, the more heat is generated. While there's no atmospheric cooling, radiative cooling in space is slow. This intense heat can still lead to:

            Rail Erosion and Damage: The rails can melt, vaporize, and deform due to high current and friction, leading to rapid wear and tear. Maintaining the integrity of the rails for even a single launch would be incredibly difficult.

        Structural Integrity and Alignment: The Lorentz force not only propels the armature but also pushes the rails themselves apart. Over a 1,620 km length, maintaining precise alignment and structural rigidity against these immense repulsive forces, especially in the vacuum of space where traditional support structures are absent, is a monumental challenge.

        Efficiency Loss: A significant portion of the electrical energy would still be lost as heat due to the resistance of the rails and the armature. As the gun gets longer, these resistive losses become more pronounced, reducing the overall efficiency of converting electrical energy into kinetic energy for the projectile.

        Payload Hardening: While 90 G's is less extreme than 30,000 G's, a scientific instrument package would still need to be custom-designed and built to withstand such forces, which is a specialized field of engineering for space-qualified components.

Considering Solutions for Scientific Intercepts in Vacuum

With the atmosphere removed from the equation, the focus shifts entirely to the scale and engineering complexity of the railgun itself:

  • Truly Space-Based Construction: The most direct (though still immensely challenging) concept would be a railgun constructed in orbit or on a celestial body without a significant atmosphere (like the Moon). This would be a colossal undertaking, requiring unprecedented levels of robotic assembly and resource utilization in space.

        Modular Construction and Deployment: Such a long structure would almost certainly need to be built in modular sections, assembled and aligned in space.

        Circular Accelerators/Mass Drivers: As mentioned previously, a very long, low-G circular electromagnetic launcher in space could gradually accelerate a payload to extreme velocities over many orbits, minimizing instantaneous G-forces and potentially allowing for continuous operation. This is often referred to as a "mass driver" for space launch.

        Advanced Materials: Development of new materials with extremely low electrical resistance, high thermal conductivity (for heat dissipation), and incredible structural strength would be essential.

In conclusion, while a railgun operating in vacuum theoretically possesses the capability to achieve the necessary velocity for an interstellar intercept, the sheer scale required (a 1,620 km launcher) and the associated engineering challenges in power delivery, heat management, structural integrity, and material science remain monumental hurdles. It's a testament to the power of the concept, but also a clear indicator of the immense technological leap required for such an application.

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#17 2025-07-29 17:53:00

tahanson43206
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Registered: 2018-04-27
Posts: 22,557

Re: Magnetic Launch Electromagnetic Launch Rail Gun

In this post Gemini tackles a hypothetical that turns out to be ** way ** outside what we have learned is possible:

Thank you for working out this result. While the result is disappointing, I think that it would be enlightening to a reader who might be curious to know what would be involved. The response you provided is not quite ready for BBCode presentation, since the equations are not rendered in text form. Would you be willing to make that adjustment?

Railgun Parameters for Interstellar Intercept: Revised Constraints (BBCode Version)

Thank you for that feedback! You're absolutely right, ensuring the equations are readable in plain text is essential for BBCode. Let's get this ready for your forum.

Given your new constraints for a railgun operating in vacuum:

  • Desired Final Velocity (vf): 54 km/s (54,000 m/s)

        Maximum Railgun Length (d): 2 km (2,000 m)

        Initial Velocity (vi): 0 m/s (starting from rest)

We can use standard kinematic equations to determine the required acceleration (a) and the time (t) it will take.

Calculations in Plain Text
  • Step 1: Calculate the Required Acceleration (a)
        We use the equation: vf^2 = vi^2 + 2ad
        (This equation relates final velocity, initial velocity, acceleration, and distance.)

        Plugging in our values:
        (54,000 m/s)^2 = (0 m/s)^2 + 2 * a * (2,000 m)
        2,916,000,000 m^2/s^2 = 0 + 4,000 m * a
        2,916,000,000 = 4,000 * a
        a = 2,916,000,000 / 4,000
        a = 729,000 m/s^2

        Step 2: Convert Acceleration to G-forces
        To better understand the magnitude, we convert this to G's.
        (1 G is approximately 9.80665 m/s^2)

        a_G = 729,000 m/s^2 / 9.80665 m/s^2 per G
        a_G approx 74,337 G's

        Step 3: Calculate the Time of Acceleration (t)
        Now that we have the acceleration, we can find the time using: vf = vi + at
        (This equation relates final velocity, initial velocity, acceleration, and time.)

        Plugging in our values:
        54,000 m/s = 0 m/s + (729,000 m/s^2) * t
        54,000 = 729,000 * t
        t = 54,000 / 729,000
        t approx 0.07407 seconds (or approximately 74.1 milliseconds)
        /*

Implications of the New Constraints for a Vacuum-Based System
  • Extreme Acceleration: The required acceleration of 74,337 G's is significantly higher than the 30,000 G's reported for military railgun projectiles. This means the instrument package would need to be designed to withstand truly extraordinary, instantaneous forces, far exceeding what most conventional space-qualified electronics can tolerate. Specialized materials, advanced structural design, and internal dampening systems would be absolutely paramount.

        Very Short Acceleration Time: The acceleration happens in an extremely brief duration – just over 74 milliseconds. This rapid acceleration means that the peak power delivery to the railgun would need to be even more instantaneous and immense than previously considered. Energy storage and discharge mechanisms would need to be incredibly efficient and robust.

        Increased Stress on Rails: The higher acceleration (and thus higher forces) over the 2 km length would place even greater, instantaneous stress on the rails. Issues of structural integrity, wear, and heat management (even in vacuum, where heat must be radiated away) would be exacerbated. The peak currents required to generate such forces would be astronomical, leading to significant thermal loads.

        Precision and Stability: Accelerating a payload to such extreme speeds in such a short time over 2 km would require unprecedented precision in rail alignment and armature stability to prevent damage or loss of the payload.
        /*

While fixing the length to 2 km makes the physical structure more manageable for lunar or orbital installation, it comes at the cost of significantly increasing the required acceleration. This shifts the primary challenge from building an impossibly long structure to designing a payload and railgun system capable of surviving and delivering such extreme, instantaneous forces and power.

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#18 2025-07-29 18:01:55

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 22,557

Re: Magnetic Launch Electromagnetic Launch Rail Gun

In this post, Gemini and I consider a rail gun that operates at the 30,000 G level.  Calculations arrived at a rail length of 5 kilometers.

Thank you for working out this result. While the result is disappointing, I think that it would be enlightening to a reader who might be curious to know what would be involved. The response you provided is not quite ready for BBCode presentation, since the equations are not rendered in text form. Would you be willing to make that adjustment?

Railgun Parameters for Interstellar Intercept: Revised Constraints (BBCode Version)

Thank you for that feedback! You're absolutely right, ensuring the equations are readable in plain text is essential for BBCode. Let's get this ready for your forum.

Given your new constraints for a railgun operating in vacuum:

  • Desired Final Velocity (vf): 54 km/s (54,000 m/s)

        Maximum Railgun Length (d): 2 km (2,000 m)

        Initial Velocity (vi): 0 m/s (starting from rest)

We can use standard kinematic equations to determine the required acceleration (a) and the time (t) it will take.

Calculations in Plain Text
  • Step 1: Calculate the Required Acceleration (a)
        We use the equation: vf^2 = vi^2 + 2ad
        (This equation relates final velocity, initial velocity, acceleration, and distance.)

        Plugging in our values:
        (54,000 m/s)^2 = (0 m/s)^2 + 2 * a * (2,000 m)
        2,916,000,000 m^2/s^2 = 0 + 4,000 m * a
        2,916,000,000 = 4,000 * a
        a = 2,916,000,000 / 4,000
        a = 729,000 m/s^2

        Step 2: Convert Acceleration to G-forces
        To better understand the magnitude, we convert this to G's.
        (1 G is approximately 9.80665 m/s^2)

        a_G = 729,000 m/s^2 / 9.80665 m/s^2 per G
        a_G approx 74,337 G's

        Step 3: Calculate the Time of Acceleration (t)
        Now that we have the acceleration, we can find the time using: vf = vi + at
        (This equation relates final velocity, initial velocity, acceleration, and time.)

        Plugging in our values:
        54,000 m/s = 0 m/s + (729,000 m/s^2) * t
        54,000 = 729,000 * t
        t = 54,000 / 729,000
        t approx 0.07407 seconds (or approximately 74.1 milliseconds)
        /*

Implications of the New Constraints for a Vacuum-Based System
  • Extreme Acceleration: The required acceleration of 74,337 G's is significantly higher than the 30,000 G's reported for military railgun projectiles. This means the instrument package would need to be designed to withstand truly extraordinary, instantaneous forces, far exceeding what most conventional space-qualified electronics can tolerate. Specialized materials, advanced structural design, and internal dampening systems would be absolutely paramount.

        Very Short Acceleration Time: The acceleration happens in an extremely brief duration – just over 74 milliseconds. This rapid acceleration means that the peak power delivery to the railgun would need to be even more instantaneous and immense than previously considered. Energy storage and discharge mechanisms would need to be incredibly efficient and robust.

        Increased Stress on Rails: The higher acceleration (and thus higher forces) over the 2 km length would place even greater, instantaneous stress on the rails. Issues of structural integrity, wear, and heat management (even in vacuum, where heat must be radiated away) would be exacerbated. The peak currents required to generate such forces would be astronomical, leading to significant thermal loads.

        Precision and Stability: Accelerating a payload to such extreme speeds in such a short time over 2 km would require unprecedented precision in rail alignment and armature stability to prevent damage or loss of the payload.
        /*

While fixing the length to 2 km makes the physical structure more manageable for lunar or orbital installation, it comes at the cost of significantly increasing the required acceleration. This shifts the primary challenge from building an impossibly long structure to designing a payload and railgun system capable of surviving and delivering such extreme, instantaneous forces and power.

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#19 2025-07-29 18:20:03

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 22,557

Re: Magnetic Launch Electromagnetic Launch Rail Gun

We decided to wrap this series for today...

Let's call it a successful day! While further adjustments might help to improve the big picture, I think we have established that it is within the realm of possibility for humans to design a rail gun accelerator able to intercept interstellar visitors. I am reminded of the history of LIGO, or of giant particle accelerators, or the ITER fusion device, or the Laser Implosion fusion device, or the james Webb space telescope, or the Apollo Moon landings.

A Successful Exploration: Railguns and Interstellar Intercepts

That's an excellent way to frame our conclusion for today! I agree wholeheartedly. While the engineering challenges are undeniably immense, our discussions have indeed shown that accelerating a payload to interstellar intercept velocities using a railgun is within the realm of physical possibility, given sufficient advances in materials science, power systems, and payload hardening.

Your comparison to projects like LIGO, particle accelerators, ITER, laser fusion, the James Webb Space Telescope, and the Apollo Moon landings is very apt. These are all examples of endeavors that, at their inception, pushed the boundaries of what was thought achievable, requiring unprecedented levels of funding, ingenuity, and sustained effort. The railgun for interstellar intercept certainly fits into that category of grand scientific and engineering ambition.

It's been a truly interesting and educational series of exchanges. I'm glad we could explore these concepts in detail and provide a clear picture for your forum readers.

If you have any further questions or wish to delve into other aspects, please don't hesitate to ask!

(th)

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