Martian Emigrant

Double-C Seismic Accelerometer doesn't measure Centrifugal force

7 posts in this topic

Posted (edited)

Hey all.

 

I am a bit dumbfounded. Nice word that.

 

I built a station. The Jool Station. Diameter 37.6m according to the VAB Engineer's Report.

YkM1Oqz.png

For curiosity I attached a Seismic Accelerometer to the large ring and one to a small ring and spun it.

Lags of course but the MET gives 7sec per revolution. That's about 14 RPM.

The darn thing displays 00.0g. What gives?

When I ignite the engines they show a value.....

Should we call that a bug? And oversight certainly. Unless it just can't generate 0.1g....Which I doubt.

 

ME

 

Edited by Martian Emigrant

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I think it just isn't there, no real usage and maybe hard to make

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Yeah, this is due to a small detail of how KSP calculates physics. A lot of things - seismometer included - simplify physics for the whole craft to the physics experienced at the overall center of mass of the craft. Engine force produces a linear acceleration of the CoM. Rotation around the CoM produces zero acceleration of the CoM.

If you manage to have a central rotor with centrifuge pods that are independent craft, captured in place by collider intersections (aka krakentech), those pods will experience the acceleration you're looking for. The central rotor will still report zero. 

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1 hour ago, fourfa said:

Yeah, this is due to a small detail of how KSP calculates physics. A lot of things - seismometer included - simplify physics for the whole craft to the physics experienced at the overall center of mass of the craft. Engine force produces a linear acceleration of the CoM. Rotation around the CoM produces zero acceleration of the CoM.

If you manage to have a central rotor with centrifuge pods that are independent craft, captured in place by collider intersections (aka krakentech), those pods will experience the acceleration you're looking for. The central rotor will still report zero. 

Ah.

Something I can understand.

Of course the device doesn't read where it is. (Insert Face Palm)

It read for the parent body. Duh.

Thank you.^_^

 

ME

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Or, the engineers who built the accelerometer remembered being told that centrifugal force isn't real, and designed the instrument to only report on real forces.  That's why it is so expensive.

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On 4/21/2017 at 11:38 AM, suicidejunkie said:

Or, the engineers who built the accelerometer remembered being told that centrifugal force isn't real, and designed the instrument to only report on real forces.  That's why it is so expensive.

Shouldn't it measure centripetal force, then?  :P

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I imagine the reason behind this is similar to why KER can't detect acceleration coming from RCS thrusters or acceleration due to gravity - only works with currently attached engines :)

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