MMX skins.

[dakota196]

How does one get the skins from an existing model get added to the plans for a MMX? I am having a senior moment?

 

[GlenP]

How does one get the skins from an existing model get added to the plans for a MMX? I am having a senior moment?

You might just print them at a smaller scale, according to the body tube outer diameter ratio? Not sure what you mean.

 

[dakota196]

How do I get it to look like this? Body color, markings and layout?

 

[GlenP]

If that is a mini 13 mm power model, then print it at 50% for a 6.5 mm MMX power model.

 

[ep29030]

that Red Max sheet, printed at 100%, is designed to fit an Estes BT-20 airframe. I built that kit. Chris carefully measured and laid out that template. I think he uses Adobe Illustrator, but any drawing software can be used. Takes quite a bit of time. You need the original decals in digital form, then reduce them and place them where they should go once the template is printed. A tedious job that requires several printings to get it right.

 

[GlenP]

that Red Max sheet, printed at 100%, is designed to fit an Estes BT-20 airframe. I built that kit. Chris carefully measured and laid out that template. I think he uses Adobe Illustrator, but any drawing software can be used. Takes quite a bit of time. You need the original decals in digital form, then reduce them and place them where they should go once the template is printed. A tedious job that requires several printings to get it right.

I think it is for a BT-5. Still just a hypothetical example, not sure what “existing model” the OP is talking about.

 

[ep29030]

View attachment 575823

I think it is for a BT-5. Still just a hypothetical example, not sure what “existing model” the OP is talking about.

Oops, you are correct. It is a BT-5 kit. Here is mine. I left it for mini-motors rather than MMX.

 

[dakota196]

Mark, that is what I needed to know. I would like to know how they do it, within the program. I haven’t read or seen any information on the process. I would like to learn.

 

[GlenP]

For any particular rocket you have in mind? Which particular kit do you want to make in MMX size?

There are several good drawing programs on the computer, and many scans of decal sheets available on the JimZ model rocket plans site.

You don't need to buy any expensive software, there are good free options, but they require a bit of learning. GIMPshop and InkScape are good free alternatives.

 

[dakota196]

I guess it’s all going to be trial and error.

 

[GlenP]

Great, good luck with that particular rocket!

 

[kuririn]

I guess it’s all going to be trial and error.

Actually it's just math, specifically ratios and percentages.

How do I get it to look like this? Body color, markings and layout?

For example, to downscale from a BT5 airframe to a minimum diameter MX airframe find the ratio of the smaller tube OD to the larger tube OD. That would be 0.281" to 0.543", or 52%.
Then instead of printing the skins at actual (100%) size change the printer settings to 52% and highest resolution for the richest color saturation and detail. See GlenP's post above.
Then print, cut out and assemble per instructions.
However.................
For me I find that minimum diameter MX rockets are too small and difficult to find in the field.
I would just print the BT-5 skins at full size and sub an MX motor mount.
They are cardstock and small and light enough to fly on MX motors.
Also assembling a full size BT-5 cardstock rocket is difficult enough, the difficulty is amplified with MX size skins and wraps.
Anyway, erockets has a selection of body tubes from BT-1 to BT-5 suitable for MX rocket downscales as well as a limited selection of nose cones for MX.
Good luck on your MX journey.

 

[GlenP]

Which existing model kit do you want to build in an MMX size?

 

[dakota196]

Nike Ajax for one.

 

[dakota196]

I guess I could just get the OR file and downscale it and then get the fin patterns and go from there. And the paint it all. But that would be too heavy. Really like to to do what Chris has done in my post above. Layout and patterns all on one sheet.

 

[GlenP]

That will be a good one. For starters we can find info on the model here:

https://www.spacemodeling.org/jimz/est1279.htm
We can gather some dimensions from that, and maybe use the motor dia or the outside main body dia as a scaling factor to see if that works. Sometimes you might have to deviate from scale to get the rocket stable, like stretch the length a little if you are limited by nose weight, for example.

 

[dakota196]

That will be a good one. For starters we can find info on the model here:

https://www.spacemodeling.org/jimz/est1279.htm
We can gather some dimensions from that, and maybe use the motor dia or the outside main body dia as a scaling factor to see if that works. Sometimes you might have to deviate from scale to get the rocket stable, like stretch the length a little if you are limited by nose weight, for example.

I have the OR file for the TLP version and I down scaled it. Bt5 booster version will be around 11”, just for comparison.

 

[GlenP]

Lots of body tube diameters in this kit, when you downscale does it stick to standard body tube sizes? What does a dimensioned side view look like in your resized OR view, can you post a screenshot?

 

[GlenP]

I am going to admit defeat on this one, I was hoping to walk you through my process of making an MMX model from an existing kit, but with the length of this one and all the different body diameters, it would really require some major simplifications and not really going to be easy to come up with a cardstock wrap for all those different portions of the model, I am not sure if it would come in light enough for MMX power, might be better candidate for a 13mm downscale or for a 3D printed model to retain the scale lines.

The Estes NIKE Ajax kit has BT-20J, BT-55KA, BT-50, BT-20 and a balsa transition TA2050B. Not saying that this is not possible, but would require a lot of artistic license and most likely deviation from the scale lines of the kit, unless you make your own non-standard dia body tubes. Just not a good example kit for me to demonstrate my process of how to create an MMX cardstock body tube wrap, when you have like 4 different diameters to work with.

A Nike Smoke might make a better first lesson,

https://www.rocketryforum.com/threads/does-anybody-make-a-micro-nike-smoke.145021/#post-1771226

 

[GlenP]

This is the drawing I made for the Nike Smoke, using InkScape. I usually include a reference 1" square to ensure that the image on screen prints out to the correct size on paper. InkScape lets you size boxes to the correct dimensions on screen in inches or mm. For the width of a tube wrap, you can wrap a body tube with a strip of the paper you plan to use, mark it after one wrap, then measure that, it varies depending on thickness of your paper, but a starting point is going to be Pi*dia of tube, plus an allowance for thickness. I usually don't wrap a body tube, but I make the tube from the paper and use engines or a dowel as a mandrel to help form the tube. If one layer is not strong enough, I will double it up and use two layers. A glue stick really helps lay down a smooth thin layer of glue when building these paper models or doing paper wraps around a ready-made body tube. If you have any specific questions I would be glad to help you out, just think a simpler model like a basic 4FNC would be a better first time model.

https://inkscape.org/
So, starting with this 13mm power model, do you think you could modify it to create a MMX min-dia model, as an exercise?