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Gessler

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I mean the configuration used in submarine , the remove shaft direct contact by adding motor in some new gen submarine

Wrong thread to discuss this.

Direct contact doesn't happen here either. But there are a dozen other considerations as to where best to place the gearbox/IEP.
 

Nilgiri

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What about a big electric motor at back , and connected with wires at front to move electricity

If you size this motor, you will find the problem. Have to take into account where you want to place the heaviest stuff found on ship in the free body moment diagram.

You can get away with it somewhat more on a submarine, as the whole thing submerges and you can size/place the ballast tanks to compensate (somewhat) if there is benefit to placing something big and chunky extremely on one end (and you move around other heavy stuff as well to mitigate)

....but a surface ship only has the planar sea (which it is only partially submerged in) for reaction force. So keeping heavy things as near as possible the centroid is best (for best ship layout design envelope and also turning and response needs). Less heavy things (sensors, payloads, basic structure etc) are better for extremities.

This gets a lot worse in aviation discipline as you can imagine, where there is no steady reaction force provider other than the lift (only) generated by the motion itself.
 

Lonewolf

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If you size this motor, you will find the problem. Have to take into account where you want to place the heaviest stuff found on ship in the free body moment diagram.

You can get away with it somewhat more on a submarine, as the whole thing submerges and you can size/place the ballast tanks to compensate (somewhat) if there is benefit to placing something big and chunky extremely on one end (and you move around other heavy stuff as well to mitigate)

....but a surface ship only has the planar sea (which it is only partially submerged in) for reaction force. So keeping heavy things as near as possible the centroid is best (for best ship layout design envelope and also turning and response needs). Less heavy things (sensors, payloads, basic structure etc) are better for extremities.

This gets a lot worse in aviation discipline as you can imagine, where there is no steady reaction force provider other than the lift (only) generated by the motion itself.
Yup but dual motor package is actually a bit better and lighter but in comparison to shaft , it's definitely heavy .
 

Nilgiri

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Yup but dual motor package is actually a bit better and lighter but in comparison to shaft , it's definitely heavy .

Yes but I am saying you also have to consider the distance from centre of mass.

In other axis, for an aircraft carrier, an irregular shaped runway already imposes huge design constraints on the ships innards placement and ballast tank penalty needed (to balance the whole thing).

Not from the mass/weight itself, but the distances involved of those masses w.r.t the centre of mass.

You want to avoid putting anything heavy far away from the centre as far as you possibly can. You need extremely good reason to violate this (as this needs you to then design everything else location-wise around that...and live with the far reduced agility/responsiveness or larger needs/costs to address that). It generally will not happen....and heavy things are kept as close to centre as possible.
 

Lonewolf

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Yes but I am saying you also have to consider the distance from centre of mass.

In other axis, for an aircraft carrier, an irregular shaped runway already imposes huge design constraints on the ships innards placement and ballast tank penalty needed (to balance the whole thing).

Not from the mass/weight itself, but the distances involved of those masses w.r.t the centre of mass.

You want to avoid putting anything heavy far away from the centre as far as you possibly can. You need extremely good reason to violate this (as this needs you to then design everything else location-wise around that...and live with the far reduced agility/responsiveness or larger needs/costs to address that). It generally will not happen....and heavy things are kept as close to centre as possible.
Yup I know basic Centre of mass and involvement of torque and centre of gravity .

I was proposing idea if it is feasible or not , if a new solution is found out
 
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