m4v

[1.2] RCS Build Aid v0.9.1

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I don't do GitHub releases, the zip from github only has sources. Get the binary from curse, see the original post of this thread for a link.

:mad: Darn school internet, blocking Curse. I downloaded from GitHub and was confused as heck.

I want this mod so bad.

Well, at least I know why it's not working now. I'll get it later.

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Hello folks!

I have a question:

I'm currently trying to balance my space-shuttle-esque craft with the help of RCS-Build Aid Engine-Mode. I have a main-shuttle engine and two solid rocket boosters from KW-Rocketry.

The problem with the KW-Rocketry boosters is that they behave as expected when it comes to the thrust-limiting slider in the VAB. When you put the slider at 0%, the SRB will burn at 50% of it's max thrust because that's the way they work. RCS-Build-Aid gets confused and ignores the SRB since it thinks it's not burning at all (0% thrust). KER also had this issue in it's first releases.

Can you make it so that this unexpected behaviour of KW-Rocketry SRB's gets processed correctly.

If you need something from me, I can supply save files, craft files, logs, whatever you need to make it happen. :)

I love your mod and it makes designing complex thrust set-ups so much easier.

Cheers!

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Hello folks!

I have a question:

I'm currently trying to balance my space-shuttle-esque craft with the help of RCS-Build Aid Engine-Mode. I have a main-shuttle engine and two solid rocket boosters from KW-Rocketry.

The problem with the KW-Rocketry boosters is that they behave as expected when it comes to the thrust-limiting slider in the VAB. When you put the slider at 0%, the SRB will burn at 50% of it's max thrust because that's the way they work. RCS-Build-Aid gets confused and ignores the SRB since it thinks it's not burning at all (0% thrust). KER also had this issue in it's first releases.

Can you make it so that this unexpected behaviour of KW-Rocketry SRB's gets processed correctly.

If you need something from me, I can supply save files, craft files, logs, whatever you need to make it happen. :)

I love your mod and it makes designing complex thrust set-ups so much easier.

Cheers!

Indeed, that's a bug that I fixed last week in git, so hang on until next release.

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Hello m4v,

just want to inform you that I intend to use a bit of your code (the PartExtensions class to be precise) in my Procedural Airships plugin. I hope you are cool with that. If you are not, I will remove the class and write my own of course. Had some trouble with incorrect mass values and your extension class does the trick just perfectly.

I will place a link to this thread on the projectthread as soon as I merged into master and released the new version.

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Hello m4v,

just want to inform you that I intend to use a bit of your code (the PartExtensions class to be precise) in my Procedural Airships plugin. I hope you are cool with that.

Is all cool, since your project is under GPL you didn't even need to ask.

Edited by m4v

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Is all cool, since your project is under GPL you didn't even need to ask.

Alright. I already assumed that the license allowes it, but I think it's always nice to let the original authors know. Also It's a good way to avoid reading long "fine-printed" license texts. :D

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Attitude mode is for the orientation of the spacecraft (ie, how the RCS will fire during rotations)

(That's simply the aerospace term for all flying / spatial vehicle to tell which direction they are facing :))

Edited by sgt_flyer

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I'm interested to know more about how RCS Build Aid calculates dV, as it's always lower than my calculation. But then too I notice that my 4 thrusters, each producing 1kN, actually only produce 3.88kN of thrust with 0 torque. Not sure why, but I suspect it is because the nozzles are not pointing straight backwards?

Ekk1tGs.jpg

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But then too I notice that my 4 thrusters, each producing 1kN, actually only produce 3.88kN of thrust with 0 torque. Not sure why, but I suspect it is because the nozzles are not pointing straight backwards?

You're correct. Not all of that force is going into accelerating the craft since the thrusters are angled.

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Not sure why, but I suspect it is because the nozzles are not pointing straight backwards?
Exactly, your effective ISP is less due to that.

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cool, thanks for the confirmation. Makes this tool all the more valuable getting to see accurate values like this

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what is it with the design of these RCS blocks that would cause such extreme rotation? No matter which way I orient them I get torque. Other 5-port blocks work fine for forward/reverse thrust.

tp5aG3x.jpg

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what is it with the design of these RCS blocks that would cause such extreme rotation? No matter which way I orient them I get torque. Other 5-port blocks work fine for forward/reverse thrust.

http://i.imgur.com/tp5aG3x.jpg

There's two things:

First, because that is just one part, (the RCS don't count as they are massless) you have all the mass concentrated in the rotation axis, and the moment of inertia (MoI) becomes zero (because it is mass * distance_from_rotation_axis ^ 2), so small amounts of torque translates in fast rotations. This is a consequence of the physics model simulating stuff as mass points, if you add more parts at some distance from the center, then the moment of inertia should increase and make the circular arrow (that represents the angular acceleration, not torque) smaller. This is also the reason of why rockets can rotate longitudinally a lot easier than they should, since most of their mass doesn't factor in because their moment of inertia is cancelled out.

Second thing that probably is happening is that the RCS (or the fuel tank) don't have their colliders perfectly aligned so no matter how you place them there's always a slight misalignment that causes some torque, which paired with the zero MoI makes it rotate easily. Try if the same happens with the stock RCS or a stock tank. The angle snap might also be playing a role.

In any case, this shouldn't be a big issue with your complete vessel, since you're going to use more parts and hopefully not all with their masses aligned in the center.

Edited by m4v

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[...] that is just one part, (the RCS don't count as they are massless) you have all the mass concentrated in the rotation axis, [...], so small amounts of torque translates in fast rotations. This is a consequence of the physics model simulating stuff as mass points, if you add more parts at some distance from the center, then the moment of inertia should increase [...]

this was a bit of a "AHA!" moment for me. I never considered the fact that every part that is stack attached is going to have all of it's mass right over the center of rotation. this explains why even the supermassive 5 meter parts can be made to spin like a top by the slightest control input, but a minor imbalance in Universal Storage wedges causes huge torque. it's also a good reason to use radial tanks, like the B9 surface attached RSC tanks to give the physics system something to grab onto.

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is there anyway this mod can be adapted to show the direction of decouples and seperatron's so that you can see how your boosters are being dropped off?

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is there anyway this mod can be adapted to show the direction of decouples and seperatron's so that you can see how your boosters are being dropped off?

The direction of the decoupler's force is fairly obvious to tell from the model, what is not obvious is the position of the CoM of the booster stage and that's a lot more difficult to code.

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Hello!

I wanted to invite you m4v to a discussion on a mod list I'm testing. Let me know in that thread if you would be interested in helping test other listed mods with yours, or if you already have. :)

Inigma's KSP Essentials Mod List

http://forum.kerbalspaceprogram.com/threads/94353-WIP-Inigma-s-KSP-Essentials-Mod-List-%28in-Testing%29

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Hi,

I noticed RCS Build Aid compiled for 0.24.x throws constant exceptions in the Editor scenes in 0.25. Rebuilt against the 0.25 assemblies and it seems to be happy again - no code changes needed, and it seems to work.

Timmers

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