Grappling Arm Errata clarification (High Guard)

[atpollard]

High Guard lists the Grapling Arm as 2 dTons in volume, 250 meters long and MCr 1.
The HG Errata adds the fact that it can manipulate "2 tons".

So can it manipulate a 2 displacement ton craft/container or a 2 metric ton object?

Does either 2 displacement tons or 2 metric tons seem a little small?

Two displacement tons is only half of a standard cargo container, so it cannot be used for cargo transfer.
A 2 metric ton vehicle would only be about 13 to 20 cubic meters and even smaller than 2 displacement tons.
In contrast, a 1 displacement ton docking clamp can wrestle a 30 displacement ton small craft into place and includes a built-in airlock.

I was just wondering if the HG errata for Grappling Arms needs errata allowing it to manipulate not 2 tons, but more like 20 displacement tons or 40 metric tons?

Any thoughts?

 

[DFW]

Any thoughts?

Yep, brain wasn't engaged when it was written. Any way you slice it makes no sense.

 

[far-trader]

Well, for comparison we know the stats for the Canadarm:

15.2m long

1.7m3

450kg

Capable of manipulating up to 29.5 mtons in space.


Scaling that up (purely linearly which is not accurate, just for a ballpark comparison... ) to 2 dtons:

~240m long

~27m3

~7,147kg

Capable of manipulating ~ 468 mtons in space (about 130 dtons if the same density as the arm itself)

 

[BP]

This is one of those aspects that should be left un-quantified, since it is very situationally dependent.

In a 'zero-G' environment its the inertia that matters most - essentially setting timing constraints for operations, but not so much mass (though there would be limits). Planet-side in a gravity well, there would be some very real limits on mass.

It is 15.2 meters long, weighs about 411 kilograms (kgs) and the latest upgrade can lift a payload of 266,000 kgs in zero gravity. On the lighter side (well, heavier side, really), it cannot lift a cup of cappuccino on the Earth’s surface.

Further, objects in relative motion (esp. accelerating) present other complications.

As a Referee, I would expect to handle this on a case-by-case basis factoring in various skills/attributes and difficulty level. What's really needed is simply the intent of the tech in this case - i.e. was it designed for maneuvering only small debris, cargo containers, and/or small craft?

[P.S. - my dad made modifications to the controller for the arm at the request of astronauts, which, IIRC, later made it into space 8) ]

 

[far-trader]

In a 'zero-G' environment its the inertia that matters most - essentially setting timing constraints for operations, but not so much mass (though there would be limits). Planet-side in a gravity well, there would be some very real limits on mass.

Quite, though the mass is important for the inertia calculations. You might well be able to (slowly) get a large mass up a good speed with the arm, and find you don't have the "strength" to bring it to rest again before it rips the arm off the mounting.

It is 15.2 meters long, weighs about 411 kilograms (kgs) and the latest upgrade can lift a payload of 266,000 kgs in zero gravity. On the lighter side (well, heavier side, really), it cannot lift a cup of cappuccino on the Earth’s surface.

IIRC it can't even support its own weight on the ground. It truly is meant to be used only in zero-g. A problem that would be even more pronounced for a 250m long arm...

...all barring some much higher tech "arm" waving

 

[atpollard]

Yeah, I looked at the Canadarm (and Canadarm 2 has much better performance). I also checked out some articulated cranes for truck and marine cargo handling. They seem to lift up to 6 times their mass at about 1/3 the maximum reach (and much less at full reach) and canadarm 2 maneuvers about 60 times its mass in space.

I was leaning towards just using the x6 and x60 for volume relative to the grappling arm ... in other words a 2 dTon cargo arm could move 12 dTon (max) on the ground and 120 dT (max) in space.

 

[far-trader]

Seems a great rule of thumb atpollard (nicked )