Calculate iron container acceleration in railgun system on the Moon

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Discussion Overview

The discussion revolves around calculating the required voltage and current for a cylindrical iron container in a vertical railgun system on the Moon, aiming for a specific exit acceleration. The context includes considerations of gravitational effects and the need to meet another spacecraft in orbit.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant outlines the parameters for calculating the required voltage and current for a 500-ton iron container to achieve a specified exit acceleration of 2 km/s² on the Moon, considering gravitational pull.
  • Another participant notes that the current required for such a mass would be extraordinarily high, referencing past experiences with railguns where much smaller masses required around 5 megaamperes for acceleration.
  • A participant inquires about the possibility of calculating the current needed using a formula, or alternatively, determining the acceleration achievable with a specific current and voltage input for a smaller mass, such as 5 kilograms.
  • A participant shares a PDF that discusses modeling and simulation of railguns, suggesting that while it may be dated, the fundamental concepts should still apply.

Areas of Agreement / Disagreement

Participants generally agree that the required current for the specified mass is extremely high, but there is no consensus on the exact calculations or formulas needed to determine the current or acceleration.

Contextual Notes

The discussion does not resolve the mathematical steps needed for the calculations, and assumptions regarding the efficiency of the railgun system and other operational parameters remain unspecified.

Who May Find This Useful

Individuals interested in railgun technology, aerospace engineering, and the physics of acceleration in low-gravity environments may find this discussion relevant.

PlanetGazer8350
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Having a cylindrical iron container with wall thickness of 20 cm, and a total weight of 500 tons when filled with its cargo, how would you be able to calculate its required voltage and current input in a vertical railgun system (relative to the Moon's surface), with an exit acceleration of 2km/s², for example? The gravitational acceleration would be 1.65km/s², pulling the cylinder due to its gravity. It should then, at an specific height, for example, 300km, meet with another spacecraft (in an elliptical orbit), just before its aphelion, with the cylinder and spacecraft having a very near velocity. Exactly what exit acceleration should be required for the cylinder to be able to reach the 300kms of height, when it is already starting to decelerate, for it to be captured by that spacecraft (the previous 2km/s² being just an example for that situation)?
 
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The current required will be out of this world in the strictest sense. Some years ago (like 15) when I was involved with rail guns, the objects being accelerated were a few pounds at most, and the currents were around 5 megaamperes to obtain about 6 km/s. Your 500 ton mass is going to require an exorbitant amount of current to reach the speeds you want.
 
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I already knew that the required current would be astronomical, but is there exactly any way of calculating the current with a formula? Or, in the other hand, calculate the acceleration with an specific current and voltage input (not in the previous case, but in a different, for example, 5 kilograms)?
 
The attached PDF describes a good bit about the modeling and simulation of a rail gun. While it is dated, the basics have to remain unchanged.
 

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