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Docking, magnets, and docking with magnets


Maria Sirona

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They tend to be either heavy (solid state magnets) or power intensive (electromagnets) or both, neither of which is particularly great for spacecraft.

Also tricky for fine control. For real spacecraft staying aligned to a docking target with thrusters isn't a huge deal, so the benefit is marginal.

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13 minutes ago, Vanamonde said:

In real world applications I don't think you'd want metallic objects to be attracted and stuck to your ship. 

It's not other around you anyway and the metal who is if moving way faster than bullets and very little is affected by magnets. 
See this as more useful for small probes like Mars sample return or perhaps refueling satellites or grabbing them for reuse or disposable in ways the video above shows. 
 

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yea the way 2 ports slam together in ksp is somewhat problematic for some constructions. this has broken many a station of mine. so a lot of cases i turn down the attraction as much as possible.  mechanical ports almost always seem like a better idea. 

you also have to realize that most spacecraft will have their rcs ports placed at optimal locations and are not slapped on willy nilly as an afterthought like with your usual ksp spacecraft. while its fun docking with a dead elephant on your back, probibly wouldn't work in real world spaceflight. 

Edited by Nuke
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11 hours ago, Vanamonde said:

In real world applications I don't think you'd want metallic objects to be attracted and stuck to your ship. 

The moving part of the actual APAS-derived docking port is a metal pipe ring 1.2 m in diameter, ~5 cm wide, ~8 cm high, with three hollow petals, just several tens kilograms heavy.

It's attached to three pairs of trusses with fine rotation joints.

So, there is no need in powerful electromagnets to get two rings into contact from less than a meter distance.
Any of their electromotors contains comparable magnets.

Edited by kerbiloid
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5 hours ago, TheSaint said:

IRL, OMG, such a bad idea. Pulling you together when you don't want to be together. Not letting you be apart. it's like a bad relationship.

The magnets should not pull the ship.

They should pull the soft capture rings until the soft capture latches click, instead of the petals collision like now, which is stil a mechanical collision, even if soft.

The magnets should adjust the soft capture rings before their "physical" contact, to let the latches match each other and lock at zero contact speed.

Then it's always as usual. Once the soft capture rings are latched, the retractable trusses adjust the vessel axes in one line and pull the ships together.
Then, once the electromangetic or mechanical strikers  click, the hardware mechanical latches (say, the hooks, like now, or collets like sometimes) lock, and the ships get locked together.

***

This allows to avoid using the mechanical petals (they get replaced by the magnetic field).

First, this makes the contact much softer, what is important for  superheavy ships.

Second, currently they have a standard 800 mm clearance between the petals.
Though, when the soft capture system is manually unmounted, this gives a 1250 mm wide tunnel (and the CBM standard matches this size by having the squared opening 1270 mm wide).

But this requires the manual disassembling.

In iLIDS and IDSS Rev A-B they were going to make the petals mechanically foldable, to form a 1160 mm wide passage.
But later they returned to more simplistic original APAS design with fixed petals and 800 mm wide passage.

So, now they have a 1420 mm wide IDSS adaptor with 800 mm passage (or 1250 mm if manually disassembled).

If replace the petals with the electromagnets, they could get a 1420 mm adaptor with 1250 mm passage ready to use.
Or a minimalistic 1000 m wide adaptor with 800 mm passage for the light crewed ships.

So, the electromagnetic soft capture is a future, but not currently in use.

***

Magnets instead of petals.

Spoiler

NDS_docking_tests.gif

 

Edited by kerbiloid
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13 hours ago, Nuke said:

u also have to realize that most spacecraft will have their rcs ports placed at optimal locations and are not slapped on willy nilly as an afterthought like with your usual ksp spacecraft. while its fun docking with a dead elephant on your back, probibly wouldn't work in real world spaceflight. 

Well i certainly put my thrusters carefully

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22 hours ago, RCgothic said:

They tend to be either heavy (solid state magnets) or power intensive (electromagnets) or both, neither of which is particularly great for spacecraft.

Also tricky for fine control. For real spacecraft staying aligned to a docking target with thrusters isn't a huge deal, so the benefit is marginal.

I guess you could also use mechanically moved and tracking "arms" to bring craft together, as the ISS/space shuttle already uses/used. Either an arm, or a multi directional adjustable port, that then pulls the craft in, making small adjustments to their angles.

https://www.internationaldockingstandard.com/

diagram1.gif

As you can see, it has a large degree of motion and adjustment to help meet/match up different angles.

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1 hour ago, Technical Ben said:

I guess you could also use mechanically moved and tracking "arms" to bring craft together, as the ISS/space shuttle already uses/used. Either an arm, or a multi directional adjustable port, that then pulls the craft in, making small adjustments to their angles.

https://www.internationaldockingstandard.com/

diagram1.gif

As you can see, it has a large degree of motion and adjustment to help meet/match up different angles.

Yes, first you soft dock with the extended ring this is then pulled inn and you get hard dock who is air thigh and more secure. 

Magnets will not help here, now on small satellites magnetism might help in docking, as seen in the video it does not need to be slamming together like in KSP.  

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7 hours ago, magnemoe said:

Yes, first you soft dock with the extended ring this is then pulled inn and you get hard dock who is air thigh and more secure. 

Magnets will not help here, now on small satellites magnetism might help in docking, as seen in the video it does not need to be slamming together like in KSP.  

It could depend. If you have active tracking via cameras or lasers, you can just use motors to align the rings/petals and grab in (or mechanically just "nudge" the two craft together :P ).

If wanting a passive system, magnets could work. Problem being, small iron/magnetic metal chips could start to clog the mechanisms, and this would probably be decided to be more risk and danger, than just taking it slower on approach and doing it some other way.

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19 hours ago, Technical Ben said:

It could depend. If you have active tracking via cameras or lasers, you can just use motors to align the rings/petals and grab in (or mechanically just "nudge" the two craft together :P ).

If wanting a passive system, magnets could work. Problem being, small iron/magnetic metal chips could start to clog the mechanisms, and this would probably be decided to be more risk and danger, than just taking it slower on approach and doing it some other way.

Yes, I don't think magnets will work well for the international docking adapter. For one it take up space inside the pressurized area once its redraw and hard dock and you handle +5 ton tons spaceships.
I see it as might be relevant for smaller unmanned stuff where an soft docking system will be much heavier than magnets. 

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those coils need not be huge and you can do things with switching to lower the force needed as a function of distance. the inverse square law would make this seem difficult, but because you know the scaling you can match it.

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