Upscale How-To available?

YeahImJosh said:

As far as the fins go, what program do you use to create the new templates?

Click to expand...

I use a couple of different programs: The GIMP and Inkscape. Both are free, open source programs and both have excellent reputations. There are learning curves associated with both of them, but online help is available. The scale tools of each one are easy to use (especially GIMP's), once you learn where they are.

GIMP 2.6
Download Inkscape 0.48.1

For fin wrapping guides, shroud/transition templates and centering ring templates, I use the excellent tools at Roger Smith's (jadebox) Payload Bay web site. Especially with the fin guides, I find that the patterns that are printed with the plans can often be just slightly off, and scaling them can make that discrepancy worse. So I prefer to make fresh ones using the online tools, and tweak the settings until they fit perfectly.

https://www.payloadbay.com/page-Tools.html

There are ways to calculate and plot all of these patterns yourself, of course. It's been 40 years since the last time I did so in geometry/trigonometry class, though, so I just use the published tools.

OK, in a post in another thread I mentioned that it was actually pretty easy to measure tubes for odd or unusual lengths. I said that I would post the method here. So here it goes:

Let's say that, according to your scale calculations, you are going to need a tube that is 16.685" long. The 16" is easy enough, but what about the 0.685 part? The decimal amount 0.685 isn't easily divisible by 1/64ths, the basis of the English (American) inch fraction, nor can it be converted to an easily measured metric equivalent. How can you measure that length with a reasonable amount of accuracy?

The answer: you use your drawing program.

You can measure out 16" of tubing with a standard ruler. So go ahead and do that, and make a pencil mark on it at the 16" point.

Now go to your computer and fire up your drawing program.

Using the program, draw a rectangle. It doesn't have to be any particular length and width, because that will be taken care of next.

Now select or highlight the rectangle, and invoke the Scale feature of your program.

Make sure that the "scale proportionally" option is turned off. You want to be able to set the length and width independently, and not have one dimension automatically change when you enter in a number for the other.

Enter in a Length that will be great enough to wrap the rectangle around your tube.

For Width, enter 0.685. Click "OK" or its equivalent to change the rectangle to these dimensions.

Save the drawing, and then print out a copy.

Cut out the rectangle exactly on the lines.

Wrap the rectangle around your tube. Line up the lower edge with the 16" mark that you had previously made. Make another mark at the upper edge of the rectangular strip. Now you have measured out your exact tube length. You can proceed to cut the tube to create this precise length.

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(Coming to this thread a bit late....)

Bradycros hit on the method I use for scaling our projects. I take one dimension, and from that, I calculate a scaling factor.

I then create a spreadsheet with all the original dimensions in it. Next to it, I create a column with the scaling factor multiplied in. This way, I have in one spreadsheet the original dimensions, as well as the scaled dimensions.

Since scaling a rocket is a "best fit" proposition, unless you want to fabricate custom parts, by using a spreadsheet and formulas, you can easily fiddle the numbers until most of what you're doing hits on readily available parts.

What I typically do is have multiple columns, each one with a different scaling factor. That way, I can check and see which one best fits what we want to do.

Granted, in our case, I'm scaling full-size rockets down to large high power. However, the process still applies.

-Kevin

MarkII said:

For fin wrapping guides, shroud/transition templates and centering ring templates, I use the excellent tools at Roger Smith's (jadebox) Payload Bay web site. Especially with the fin guides, I find that the patterns that are printed with the plans can often be just slightly off, and scaling them can make that discrepancy worse. So I prefer to make fresh ones using the online tools, and tweak the settings until they fit perfectly.

https://www.payloadbay.com/page-Tools.html

There are ways to calculate and plot all of these patterns yourself, of course. It's been 40 years since the last time I did so in geometry/trigonometry class, though, so I just use the published tools.

Click to expand...

This website is awesome, just printed out a fin guide for my new BT-60 tube and it is pretty darn good!