Tank/Part lengths

[LethalDose]

Is there any information available regarding the lengths of the tanks and axially mounted parts in the game? The radii of all the parts (Tiny/0.625m, Small/1.25m, Large/2.5m) are available, but I'd like to know how long/high they are so I can make stacks with various different components are the same length.

If this info isn't available, is it appropriate to post a request for the data in the wiki forum?

Thanks!

[Smidge204]

You could figure it out quite easily then contribute that info to the wiki yourself.

1) Make a simple craft that sits on the launchpad. Note the elevation on the altimeter.

2) Insert part into craft. Note new elevation on altimeter.

3) Subtract.

4) Repeat.

This information isn't really worth having, though, IMHO. All the parts appear to be of standard increments. For example: An FL-T100 is half the height of an FL-T200, which in turn is half the height of a FL-T400, which in turn is half the height of a FL-T800.

The X200-8, -16, -32 and Jumbo 64 tanks follow the same pattern and their heights match the FL-Txxx counterparts. All of the inline RCS tanks are the "short" height.

Then you have some parts like reaction wheels, remote control modules, axial decouplers and batteries that are half or quarter that height again.

The only thing I'd really be interested in is how these things compare to the length of the trusses and beams. Probably match up just fine.

=Smidge=

[LethalDose]

You could figure it out quite easily then contribute that info to the wiki yourself.

1) Make a simple craft that sits on the launchpad. Note the elevation on the altimeter.

2) Insert part into craft. Note new elevation on altimeter.

3) Subtract.

4) Repeat.

Yes, yes, YES! Genius! LOVE IT!!!

Only problem is that it will only be precise to the nearest meter, though. I could stack multiples of the sample parts and get my regression on to try to calculate more exact lengths.

I would be much more precise, though, if this information could be nabbed from in game files.

This information isn't really worth having, though, IMHO. All the parts appear to be of standard increments. For example: An FL-T100 is half the height of an FL-T200, which in turn is half the height of a FL-T400, which in turn is half the height of a FL-T800.

The X200-8, -16, -32 and Jumbo 64 tanks follow the same pattern and their heights match the FL-Txxx counterparts. All of the inline RCS tanks are the "short" height.

Then you have some parts like reaction wheels, remote control modules, axial decouplers and batteries that are half or quarter that height again.

The only thing I'd really be interested in is how these things compare to the length of the trusses and beams. Probably match up just fine.

=Smidge=

Yeah... I totally disagree with you about the "not worth having" statement. Being able to stack things to certain height is incredibly useful in a number of applications. The issue that made me ask, though, was that I want to be sure that radially-mounted nacelles attached with multiple docking ports to line up appropriate WITHOUT relying on trial and error.

And while the TANKS follow that rule, other parts (Hitchhikers, science bays, separators, probe cores) may not necessarily follow the rules. I don't feel super comfortable with taking a "It's all cool" approach, only to find out that parts don't fit because of a few cm.

[Smidge204]

Well I don't have access to the game at the moment, otherwise I'd take a few minutes to actually try it. If it's not too much of an inconvenience, perhaps you could try it for me?

=Smidge=

[LethalDose]

It'll be a project for me later this afternoon after work, but yeah, I'll give it a shot and post what I find.

[Taki117]

A simpler plan is to just use the same ship for all your multiport docking needs. This way your ports will always be aligned.

[LethalDose]

A simpler plan is to just use the same ship for all your multiport docking needs. This way your ports will always be aligned.

If you aren't going to address the posted question, please don't respond. I don't want the responses derailed with craft design issues.

[Taki117]

If you aren't going to address the posted question, please don't respond. I don't want the responses derailed with craft design issues.

By creating one ship with the required docking port configuration, and then reusing said ship for each subsequent launch the need to know the length of the tank is eliminated because each vessel will be exactly the same with the same docking port alignment eliminating alignment errors.

[eurybaric]

Yeah... I totally disagree with you about the "not worth having" statement. Being able to stack things to certain height is incredibly useful in a number of applications. The issue that made me ask, though, was that I want to be sure that radially-mounted nacelles attached with multiple docking ports to line up appropriate WITHOUT relying on trial and error.

And while the TANKS follow that rule, other parts (Hitchhikers, science bays, separators, probe cores) may not necessarily follow the rules. I don't feel super comfortable with taking a "It's all cool" approach, only to find out that parts don't fit because of a few cm.

Agreed! now we can use smidge204's method for those too, albeit not for non-stackable parts i think. But all in all I think that there should be another way of finding precisely the measurements by config files or something! And if not accessible by the normal user, maybe the devs should release all that info ..

Cheers!

Edited November 28, 2013 by eurybaric
forgot some words lol

[numerobis]

Probably this is a question to ask in the modding forums?

[UmbralRaptor]

For objects with nodes at both ends, you can find the relative positions in part.cfg files and subtract.

[DrMonte]

Is there any information available regarding the lengths of the tanks and axially mounted parts in the game? The radii of all the parts (Tiny/0.625m, Small/1.25m, Large/2.5m) are available, but I'd like to know how long/high they are so I can make stacks with various different components are the same length.

If this info isn't available, is it appropriate to post a request for the data in the wiki forum?

Thanks!

I don't see the issue. You answered your question yourself - (Tiny/0.625m, Small/1.25m, Large/2.5m) - take any part or number of parts you would like to measure and attach to the T, S or L tank end. I think you will do the rest of the math like 7 decouplers equals one Large fuel tank end.

If you need a hint how to attach use "Cubic Octagonal Strut" attached on the fuel tank side in this way:

|--Fuel tank. Side attachment.

|

|

|

|

|--Any part. Center attachment.

[Stone Blue]

Maybe this might help?:

http://forum.kerbalspaceprogram.com/threads/37196-20-x-Jeb-s-Big-Stick-For-all-your-large-measuring-needs-v1-0

[LethalDose]

So, I attempted umbralraptor's method. I couldn't find a "parts.cfg" file, but I did find parts and their positions in the VAB ship files. I created several "ships" just by stacking 2 1.25m tanks on top of each other, which produced the following results:

[table=width: 400]

[tr]

[td]Tank[/td]

[td]1st position[/td]

[td]2nd position[/td]

[td]delta d[/td]

[/tr]

[tr]

[td]FLT 100[/td]

[td]0, 5, 0[/td]

[td]0, 5.625, 0[/td]

[td]0.625[/td]

[/tr]

[tr]

[td]FLT 200[/td]

[td]0, 5, 0[/td]

[td]0, 6.1105, 0[/td]

[td]1.1105[/td]

[/tr]

[tr]

[td]FLT 400[/td]

[td]0, 5, 0[/td]

[td]0, 6.87819, 0[/td]

[td]1.87819[/td]

[/tr]

[tr]

[td]FLT 800[/td]

[td]0, 5, 0[/td]

[td]0, 8.7625, 0[/td]

[td]3.7625[/td]

[/tr]

[/table]

So... the differences in heights are not even multiples of each other. I'm really not quite sure how to interpret these results, because it flies right in the face of what everyone has posted here about larger tanks being twice as tall as the next smaller tank. Is there some kind of spacer between tanks?

I haven't gotten the data for the regression method yet.

[Smidge204]

Huh. Could've fooled me for sure. Looks like the FL-T200 is just a hair under 2/3 of a FL-T400. That's really odd since the big tanks totally do work like how I said:

I'm guessing it's a legacy thing? Old part model? Just avoid using the FL-T200 and everything will be nice multiples.

=Smidge=

[LethalDose]

I'm guessing it's a legacy thing? Old part model? Just avoid using the FL-T200 and everything will be nice multiples.

=Smidge=

They're close, but they're still not exact multiples, which is pretty surprising.

Anyway, I think it's enough to demonstrate that the previous assumptions are worth questioning and the length data have a place in the part descriptions.

[Dante80]

There is another way to measure (and utilize the info given for) tank parts. You can use a mod called stretchy tanks. This adds tanks of variable height and diameters, adjustable by you. It also features precise info about the height of the tanks in the mod.

http://forum.kerbalspaceprogram.com/threads/57422

You can either substitute the stock tanks for stretchy tanks and take advantage of the precise dimensions and customization the mod gives, or use them in the VAB to measure other parts with an extreme degree of accuracy.

Hope that helps, cheers..C:

[UmbralRaptor]

So, I attempted umbralraptor's method. I couldn't find a "parts.cfg"

/KSP/GamedData/Squad/Parts/FuelTank/

Check in each subfolder for a part.cfg file.

[DrMonte]

So it seems smaller fuel tanks have additional rings to harden them.

[numerobis]

/KSP/GamedData/Squad/Parts/FuelTank/

Check in each subfolder for a part.cfg file.

I don't remember any information about the geometry of the part in that file, except for the scale factor.

[LethalDose]

/KSP/GamedData/Squad/Parts/FuelTank/

Check in each subfolder for a part.cfg file.

Ah HA! Thanks UmbralRaptor, found them.

I don't remember any information about the geometry of the part in that file, except for the scale factor.

I believe there is geometry data in the //--- node definitions section. Specifically, I think node_stack_top & node_stack_bottom values indicate how far the part's distal (away from craft "center") connection point is from it's proximal (towards craft "center") connection.

And, as if my previous findings weren't weird enough, check THIS out: The node distances from the top to the bottom of a piece don't always equal the distance from bottom to the top!

For example, from fuelTank_long.cfg:

node_stack_top = 0.0, 15, 0.0, 0.0, 1.0, 0.0

node_stack_bottom = 0.0, -15.1, 0.0, 0.0, 1.0, 0.0

I'm guessing the differences have something to do with adding a very small amount of space between tanks to allow some literal "wiggle room" for the wobble during flight, allow gravity to compress stacks, or some other physics gameplay concept.

The values are consistently 4 times the results I was getting from my previous results, within a few decimal places. I think the initial values I reported above are in meters. I took an FLT 800 tank and was able to fit 3 BZ-52 radial attachment points along it's long axis. Assuming each BZ is ~ 1.25m in dia, the tank should be ~ 3.75m long, which is very similar to my previous estimates of it's length (though not nearly as precise as I would like). I created a stack of these, and the relative positions were 3.7625 between each. When multiplied by the conversion factor of 4, the distance was 15.05, which is the average internodal distance given by part.cfg file. Why there's this odd scaling factor between part position in craft part files and .cfg, I can't say, but it does appear to be VERY consistent across the small number of pieces I've evaluated.

I think I'm beating this into the ground, and it's time to actually start generating results to add to the Wiki. I'm going to use the following formula to estimate part height, hpart, using the part.cfg files:

hpart = Dbar / c

where:

Dbar = [node_stack_top - node_stack_bottom]/2 ; Dbar is the mean internodal distance. Note, node_stack_bottom has a negative value.

c = 4; c is the conversion factor, determined as above.

I'm also going to track, but not report, the internodal discrepancies (node_stack_top + node_stack_bottom). I'll add these to the wiki if Dbar doesn't provide enough information.

[LethalDose]

And then going through the files, the scaling factor of four doesn't make sense in a bunch of situations, particularly when I hit the engines which appear to have NO scaling factor.

CRAP!

back to the drawing board.