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Thrust point for Vernor engines


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Does anyone know precisely what coordinate in the stock vernierEngine part ("Vernor Engine", Vernier_Engine.mu) the thrust vector originates from?  The Y coordinate is offset slightly from the center of the part (by roughly 0.201m?).  I'd like to know precisely what it is, for purposes of manually editing CFG files to perfectly balance my craft.  Thanks!

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Moving to Gameplay Questions.

If I'm doing my coordinate math right, I believe the RCS thrust point is exactly 0.0162m (i.e. 1.62 cm) lower than the origin of the part.  So it's pretty darn close, but not exact.

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7 hours ago, Fwiffo said:

Does anyone know precisely what coordinate in the stock vernierEngine part ("Vernor Engine", Vernier_Engine.mu) the thrust vector originates from?  The Y coordinate is offset slightly from the center of the part (by roughly 0.201m?).  I'd like to know precisely what it is, for purposes of manually editing CFG files to perfectly balance my craft.  Thanks!

Oooh, nice find and precision.
Is it worth it though - since you don't know exactly where your CoM will be anyway, as it moves as fuel burns/mono is expended?

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Seems like RCSBuildAid is a better tool for perfectly balancing your craft. Have you tried it? It can show you resultant torque vectors for full, dry, or median CoM. Which helps design the ship for zero CoM shift in the first place, then use pixel-level movements to zero out the RCS torque.

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@fourfa Yes, I'm using it, but don't have the precision to get it it right down to 0.  Even when fully zoomed in (using WASD Cam), when I have 4 Vernors in mirror symmetry around an empty X200-16 tank, the best I can get it to with pixel-level mouse movements is about 0.003 kNm.  I'm a perfectionist for this particular craft and want it at exactly 0, hence am editing the CFG by hand.  Was hoping someone knew from the mu or code or something exactly where the thrust point was.

By trial and error I found using a Y offset of 0.2009m zeroed out my torque (at least to the 3 decimals RCS Build Aid shows).  e.g. If your tank is at Y = 15m (default for first part), place the Vernors at Y = 15.2009.

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I see.  I have often been able to get it to exactly zero.  Sometimes if it won't zero out, there's some asymmetry in the ship.  I often use a single RTG as power source, and by free-offsetting it around the CoM can get things completely zeroed out relative to the engine vector.  Then, once the ship is completely balanced in the axial dimension, usually the RCS will balance as well.

Edited by fourfa
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22 hours ago, Pecan said:

Is it worth it though - since you don't know exactly where your CoM will be anyway, as it moves as fuel burns/mono is expended?

If you have a single fuel tank exactly at the CoM, this doesn't happen.  You can scale this idea out to multiple expendable resources so long as they're oriented such that they balance each other out as they're consumed.  In my case, it's allowing me to use 4 Vernors instead of 8 (I'm using weldments, and a design goal of this craft is to aggressively reduce part count).

20 hours ago, fourfa said:

see.  I have often been able to get it to exactly zero.  Sometimes if it won't zero out, there's some asymmetry in the ship.

Easy to do when you have fuel in the tank, harder when you empty all your expendable resources to make RCS Build Aid more precise :-)

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