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-   -   Converting station(s) to dimensions in scale (http://www.oldrocketforum.com/showthread.php?t=19302)

shockwaveriderz 02-06-2021 08:04 AM

Converting station(s) to dimensions in scale
 
Now, some data sources do not list dimensions directly, but as “Station Numbers” (often with a “STA” prefix). So you have to work out the particular dimensions between any two given station numbers. It’s not hard, just different.

If I have a scale drawing with station numbers, how do I convert that to actual dimensions ? Can you provide some examples how to do it?

frognbuff 02-06-2021 09:46 AM

It's just subtraction! For example, if the top of the cylindrical portion of a model is at STA 100 and the bottom of the cylindrical portion is at STA 950, then the length of that section is 850 (of whatever units the drawing is using - centimeters, inches, etc). That's all there is to it.

rocketguy101 02-06-2021 10:42 AM

1 Attachment(s)
Yeah, I have to set things up in a spread sheet. Run a column of STA dimensions, then to a column of the deltas (differences). Then I add a column with the deltas multiplied by the model scale factor.

It's crazy when the "0" station isn't the bottom or the tip of the nose, but you just account for in your dimension table.

Edit: here is an example of a V2...note for some dimensions I used STA 0, others, like some fin dimensions I use the top of the fin root so drawing the fin is easier. My weird scale is for a BT-101 body. This is an xlsx file, had to zip it to upload it.

frognbuff 02-06-2021 11:05 AM

It can be frustrating when Station 0 isn't where you think it should be. In my experience, STA 0 may be tied to something like a location on the launch pad/launch rail. That way the ground segment and flight segment stations match. Even more frustrating than having to account for an oddball STA 0 when dimensioning a model is having the flight and ground segments use completely different stations when you need to work with both. You have to be aware there IS an offset (not always obvious when looking at a drawing of one or the other), and you have to know the magnitude (conversion factor, if you like) of the offset. Far easier when everything is made to align!

bernomatic 02-06-2021 11:56 AM

Quote:
Originally Posted by frognbuff
It can be frustrating when Station 0 isn't where you think it should be. In my experience, STA 0 may be tied to something like a location on the launch pad/launch rail. That way the ground segment and flight segment stations match. Even more frustrating than having to account for an oddball STA 0 when dimensioning a model is having the flight and ground segments use completely different stations when you need to work with both. You have to be aware there IS an offset (not always obvious when looking at a drawing of one or the other), and you have to know the magnitude (conversion factor, if you like) of the offset. Far easier when everything is made to align!


As a land surveyor, I have had to work with stations and offsets for all sorts of roadway projects, shoreline projects an others. Even more fun would be when roadways with differing station numbers would cross at an intersection. Or when an older drawing had a differing STA 0+00 or used a different baseline. And then of course differing survey crews would come up with a different distance between stations which would have to be accounted for.

rocketguy101 02-06-2021 01:37 PM

Peter Alway discusses scaling a rocket in his book "The Art of Scale Model Rocketry" it is available free for all from NAR at this link see pg 13

shockwaveriderz 02-06-2021 01:44 PM

Quote:
Originally Posted by rocketguy101
Peter Alway discusses scaling a rocket in his book "The Art of Scale Model Rocketry" it is available free for all from NAR at this link see pg 13


Great! Thanks!

Fuse Eh! 02-07-2021 12:31 PM

Quote:
Originally Posted by rocketguy101
Peter Alway discusses scaling a rocket in his book "The Art of Scale Model Rocketry" it is available free for all from NAR at this link see pg 13

Thanks for the link; that will be a great resource to have available.

mycrofte 02-08-2021 06:22 AM

When I worked on airplanes they were set a station numbers in inches. I think station 0 was set to potential additions on some models.
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georgegassaway 02-08-2021 05:00 PM

Check out the many Little Joe-II drawings on my website, at:

http://georgesrockets.com/GRP/Scale/DATA/LJoeData.htm

The drawings use STA numbers , with dimension lines going form most of them to show distances.

Nice thing about STA numbers is you can directly derive a length without adding up end-to-end-to-end dimensions, or having way too many dimension lines involving common start points. Just go from where you want to start, to where you want to stop.



The Space Shuttle STA numbers are wild. Different STA points for the Orbiter, ET, and SRB when stacked together. Also, in X, Y, and Z axes. Maybe I'll post and example of that later.


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