Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > Scale & Sport Scale Rocketry
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-06-2021, 08:04 AM
shockwaveriderz shockwaveriderz is offline
rocket dinosaur
 
Join Date: Mar 2005
Location: My Old Kentucky Home
Posts: 1,062
Smile 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?
__________________
"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.
Reply With Quote
  #2  
Old 02-06-2021, 09:46 AM
frognbuff frognbuff is offline
Aggressor Aerospace
 
Join Date: Oct 2012
Location: Colorado Springs, CO
Posts: 387
Default

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.
Reply With Quote
  #3  
Old 02-06-2021, 10:42 AM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 789
Default

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.
Attached Files
File Type: zip V2 model dims.zip (9.0 KB, 8 views)
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here

Last edited by rocketguy101 : 02-06-2021 at 10:58 AM.
Reply With Quote
  #4  
Old 02-06-2021, 11:05 AM
frognbuff frognbuff is offline
Aggressor Aerospace
 
Join Date: Oct 2012
Location: Colorado Springs, CO
Posts: 387
Default

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!
Reply With Quote
  #5  
Old 02-06-2021, 11:56 AM
bernomatic's Avatar
bernomatic bernomatic is offline
Master Modeler
 
Join Date: Jun 2011
Location: Cleveland, Ohio
Posts: 1,159
Default

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.
__________________
Bernard J. Herman Ohio RLS

Starport Sagitta Rockets
email bherman@sagittarockets.com

NAR # 97971 SR

What's your idea on the best way to change Washington D.C.?
Let us know at the Cantina
Sagitta Cantina

We're looking for a few good Catos, please tell us about any you may have had. Survey of Anecdotal Malfunctioning Engines or S.A.M.E.
Reply With Quote
  #6  
Old 02-09-2021, 11:12 PM
olDave olDave is offline
Craftsman
 
Join Date: Sep 2015
Posts: 130
Default Station 0

Quote:
Originally Posted by frognbuff
It can be frustrating when Station 0 isn't where you think it should be. ......


The main reason that many manufacturers (aircraft as well as missiles) use a theoretical station 0 that is located well out in front of the vehicle itself is to allow for future versions.

If you put the origin of your coordinate system exactly on the point of the nose, then any time you have a revision of the nose shape, or a growth/stretch version, or any other significant change, you would have to go through the entire drawing system and generate a new set of location dimensions for all parts, as well as re-numbering the mass properties database, and a lot of other paperwork revisions.

Almost all vehicle config changes will still be using almost all of the previous vehicle parts, so why make yourself have to do a bunch of extra work?

Placing station 0 out in front of the nose by two inches or two miles does not matter, as long as you know the definition of your coordinate axes.
__________________
NAR 20602
used to be "powderburner" in another life
Reply With Quote
  #7  
Old 02-10-2021, 06:38 AM
frognbuff frognbuff is offline
Aggressor Aerospace
 
Join Date: Oct 2012
Location: Colorado Springs, CO
Posts: 387
Default

Quote:
Originally Posted by olDave
The main reason that many manufacturers (aircraft as well as missiles) use a theoretical station 0 that is located well out in front of the vehicle itself is to allow for future versions.

If you put the origin of your coordinate system exactly on the point of the nose, then any time you have a revision of the nose shape, or a growth/stretch version, or any other significant change, you would have to go through the entire drawing system and generate a new set of location dimensions for all parts, as well as re-numbering the mass properties database, and a lot of other paperwork revisions.

Almost all vehicle config changes will still be using almost all of the previous vehicle parts, so why make yourself have to do a bunch of extra work?

Placing station 0 out in front of the nose by two inches or two miles does not matter, as long as you know the definition of your coordinate axes.


Quite possibly true for aircraft, but definitely not true for the Atlas and Delta launch systems. As stated before, the intent for these SLVs was to ensure alignment of flight and ground segments. Hard to tank a vehicle when the swing arm misses the fill/drain coupler by 10-15 feet!
Reply With Quote
  #8  
Old 02-06-2021, 01:37 PM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 789
Default

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
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here
Reply With Quote
  #9  
Old 02-06-2021, 01:44 PM
shockwaveriderz shockwaveriderz is offline
rocket dinosaur
 
Join Date: Mar 2005
Location: My Old Kentucky Home
Posts: 1,062
Default

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!
__________________
"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them.
Reply With Quote
  #10  
Old 02-07-2021, 12:31 PM
Fuse Eh!'s Avatar
Fuse Eh! Fuse Eh! is offline
Black Brant & Congreve fanatic
 
Join Date: Aug 2011
Location: Ontario, Canada
Posts: 113
Default

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.
__________________
John

Was CAR-ACF# S 337
Was NAR# 91049
Was SAM# 0323

Life begins when the countdown reaches zero!
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 10:24 PM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2021