Second end of EA-4 Strut Connector to obey angle snap

[pincushionman]

Title says it all. I spend a great deal of effort trying to get my struts to line up with one another. I don't know if it has any game mechanics changes for sure, but if the direction of the strut has any bearing on the direction of the force, or if it can change drag, it would be very useful to not have to eyeball the placement of the second end. It would sure make it easier to make it look better, at least. Especially since there is no readily available reference tools like moveable datum planes.

I have done some very cursory experiments, and the indication is that the exact placement of the strut does have some bearing on the stiffness between the attached parts. But not detailed enough to know for sure.

Edited August 19, 2016 by pincushionman

[r4pt0r]

I endorse this suggestion for the stock game.

[ZooNamedGames]

I second this suggestion.

[Red Iron Crown]

I'm not sure it can be made to work exactly like placing a regular part due to the way the second point is determined (essentially a ray is cast from the origin to wherever the cursor is when the second end is placed, the first part it intersects gets the second end.

That's not to say that there isn't room for improvement, though. The mod Editor Extensions has implemented a function where struts (and the very similar fuel lines) can be "snapped" after they are placed, it's very handy if a bit confusing to use at first. Something similar in stock to make strut and fuel line placement more symmetrical would be very welcome.

[TheEpicSquared]

I endorse this as well. And speaking of struts, another thing: Why do the struts have a length limit?? It just doesn't make sense for me to not be able to use struts after passing a certain length. In fact, this is why most of my big creations don't get into orbit, since the lack of struts means the whole contraption wobbles itself to bits.

[Red Iron Crown]

56 minutes ago, TheEpicSquared said:

I endorse this as well. And speaking of struts, another thing: Why do the struts have a length limit?? It just doesn't make sense for me to not be able to use struts after passing a certain length. In fact, this is why most of my big creations don't get into orbit, since the lack of struts means the whole contraption wobbles itself to bits.

Not sure why the limit exists, but you can change it in the cfg for the strut part if you don't mind messing with them. I did so for rigging this thing as they wouldn't go far enough without changing it:

Spoiler

 

[TheEpicSquared]

2 minutes ago, Red Iron Crown said:

Not sure why the limit exists, but you can change it in the cfg for the strut part if you don't mind messing with them. I did so for rigging this thing as they wouldn't go far enough without changing it:

  Hide contents

 

Wow! That is a damn nice ship! Does it work? I'll take a look in the cfg, thanks.

[Red Iron Crown]

13 minutes ago, TheEpicSquared said:

Wow! That is a damn nice ship! Does it work? I'll take a look in the cfg, thanks.

Well, there's no wind in KSP so I had to use other means of propulsion (earlier version).

The line you're looking for in the cfg is "maxLength = 10", change the number upward as desired (I think that's length in meters but not 100% sure).

[TheEpicSquared]

Just now, Red Iron Crown said:

Well, there's no wind in KSP so I had to use other means of propulsion (earlier version).

The line you're looking for in the cfg is "maxLength = 10", change the number upward as desired (I think that's length in meters but not 100% sure).

Ok thanks  

[ZooNamedGames]

2 hours ago, TheEpicSquared said:

I endorse this as well. And speaking of struts, another thing: Why do the struts have a length limit?? It just doesn't make sense for me to not be able to use struts after passing a certain length. In fact, this is why most of my big creations don't get into orbit, since the lack of struts means the whole contraption wobbles itself to bits.

*ahem* *cough* Kerbal Joint Reinforcement *cough*.

[TheEpicSquared]

4 minutes ago, ZooNamedGames said:

*ahem* *cough* Kerbal Joint Reinforcement *cough*.

Lol yes that's one of the first mods I downloaded. But sometimes it's just not enough (for me, at least)

[ZooNamedGames]

Just now, TheEpicSquared said:

Lol yes that's one of the first mods I downloaded. But sometimes it's just not enough (for me, at least)

How big are you building? And for what? At a point even struts can't help you.

[TheEpicSquared]

Just now, ZooNamedGames said:

How big are you building? And for what? At a point even struts can't help you.

Mostly I'm just seeing what the biggest thing I can get into orbit is. Specifically, some huge ring stations

[ZooNamedGames]

8 minutes ago, TheEpicSquared said:

Mostly I'm just seeing what the biggest thing I can get into orbit is. Specifically, some huge ring stations

well... I don't know how to help you then :| .

[TheEpicSquared]

Just now, ZooNamedGames said:

well... I don't know how to help you then :| .

No need, but thanks anyway  With the power of cfg file editing, I may be able to get it into orbit!  

[ZooNamedGames]

Just now, TheEpicSquared said:

No need, but thanks anyway  With the power of cfg file editing, I may be able to get it into orbit!  

Well good luck!

Krakenspeed!

[TheEpicSquared]

Thanks!

[Crown]

As far as I know, neither the direction nor the length of a strut influences the aerodynamic drag of a rocket or the force it can hold.

This mean you could use only one single strut in a any way possible without making influence on aerodynamics.

[Red Iron Crown]

6 minutes ago, Crown said:

As far as I know, neither the direction nor the length of a strut influences the aerodynamic drag of a rocket or the force it can hold.

This mean you could use only one single strut in a any way possible without making influence on aerodynamics.

That's my understanding, too. Only the location of the first attachment point matters, dragwise.

[pincushionman]

6 hours ago, Red Iron Crown said:

I'm not sure it can be made to work exactly like placing a regular part due to the way the second point is determined (essentially a ray is cast from the origin to wherever the cursor is when the second end is placed, the first part it intersects gets the second end.

I have been having trouble with that with my current design (trying to strut from one 1.25m tank to another around a TR-18A), but that's not necessarily what I'm worrying about. What I'm encountering is the floppy rocket is twisting under a yaw, which is real bad. In real life, these two configurations are going to behave differently under vertical and side loads:

Spoiler

That is, even under just the weight of the upper parts, the one on the right (in real life) will cause a counterclockwise twist when viewed from the top. Not much, and maybe not visible, but in real life things are way, way stiffer than they are in KSP.

In KSP, I'm not sure how the extra stiffness of struts is implemented (frankly, I'm not familiar with how stiffness is handled at all). If it's an additional stiffness added between between the centers of the two parts, then it's just visual. But it the locations of the strut ends define the load path, then it does make a difference, and small deviations from the intended direction will have noticeable coupling effects given KSP's unrealistically floppy joints. We're already aware of the differential stiffness bug that causes aircraft to roll slightly when you apply pitch, and contributes to the aircraft-twisting-and-yawing-off-the-runway problem.

I've done a little research, and it does seem that the exact placement of the struts along a single part does change the relative stiffness - it involved hanging a pod on the end of a long tank, connected to another tank via a radial attachment point:

Spoiler

The deflection was measured by looking at the Pitch value of the right-hand pod in KER. Various strut positions produced different results. But the deflections are so small I'm not sure they're not just random fluctuations. I'd need to come up with a way to up the "gain" on the measurements and isolate them from the entire structure being tilted slightly. What I really need is a reliable way to measure the difference between the orange tank axis and the white tank axis, which I'm not sure we have a tool for. And a lot more tests to determine a trend or not.

This is all somewhat unrelated to the circumferential snap problem, since it wouldn't help this setup and this setup isn't as sensitive to twist. But if the placement effect is real, then it's likely real in all directions.

3 hours ago, Red Iron Crown said:

That's my understanding, too. Only the location of the first attachment point matters, dragwise.

I'm willing to take the drag statement at face value, that sounds like the way it would have been done.

[Red Iron Crown]

@pincushionman The struts don't stiffen the joint between two parts, instead it creates new joints between them with a rigid rod connecting them at the two attachment points. In my experience triangulation works well with struts, so if you make, say, a warren truss like assembly for that interstage it gets a *lot* stiffer. (Real life pic of what I'm talking about, I don't have any KSP versions in my dropbox atm but I use far fewer for it, usually just six). 

Another example is this large mothership I made ages ago, those sets of large triangulated struts helped immensely with keeping stiff what otherwise would have been a really flexible design. Or the triangles on this single lift ring station which helped keep it from sagging excessively (there was another set of triangles further out connected to radially attached boosters but I don't have a pic handy).

In short, placement of struts is critical to their effectiveness, and using real life techniques like triangulation is key to getting the most from them.

[pincushionman]

11 minutes ago, Red Iron Crown said:

@pincushionman The struts don't stiffen the joint between two parts, instead it creates new joints between them with a rigid rod connecting them at the two attachment points. In my experience triangulation works well with struts, so if you make, say, a warren truss like assembly for that interstage it gets a *lot* stiffer. (Real life pic of what I'm talking about, I don't have any KSP versions in my dropbox atm but I use far fewer for it, usually just six). 

Another example is this large mothership I made ages ago, those sets of large triangulated struts helped immensely with keeping stiff what otherwise would have been a really flexible design. Or the triangles on this single lift ring station which helped keep it from sagging excessively (there was another set of triangles further out connected to radially attached boosters but I don't have a pic handy).

In short, placement of struts is critical to their effectiveness, and using real life techniques like triangulation is key to getting the most from them.

Okay, then, so we're on the same page here. And if the direction matters, then two ends that aren't perfectly in-line can cause coupling between bending and twist. Angle snap would help immensely in reducing that. That or the solution I see in drawing programs where holding shift snaps a drawn line to a cardinal direction. That might be a solution too, but that might be hard to implement in 3D.

[Red Iron Crown]

5 minutes ago, pincushionman said:

Okay, then, so we're on the same page here. And if the direction matters, then two ends that aren't perfectly in-line can cause coupling between bending and twist. Angle snap would help immensely in reducing that. That or the solution I see in drawing programs where holding shift snaps a drawn line to a cardinal direction. That might be a solution too, but that might be hard to implement in 3D.

Oh agreed, being able to align them more precisely than the current "by eye" method is highly desirable (and one of the reasons I use Editor Extensions).

Another stock technique I've used is to place a small part with angle snap where you want the free end of the strut to be (linear RCS thrusters work well). Use that part as an alignment guide, then remove it afterward. It's still "by eye", but it's a bit more precise and less vulnerable to parallax errors.

[pincushionman]

20 minutes ago, Red Iron Crown said:

Another stock technique I've used is to place a small part with angle snap where you want the free end of the strut to be (linear RCS thrusters work well). Use that part as an alignment guide, then remove it afterward. It's still "by eye", but it's a bit more precise and less vulnerable to parallax errors.

Oh, that's a really good idea!

[OrbitalBuzzsaw]

Yeah. Do it. And make KW med and heavy struts stock.