# An idea I might work on when I start building again.

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##### Well-Known Member
TRF Supporter
I put all my rocket building materials in storage.
It snowed this week, so a couple more like that and maybe they'll let us launch again.
I was riding my indoor trainer, which is mind numbing, and started thinking about rocket designs.
I was thinking some sort of insect like fin design could be interesting.

#### dhbarr

##### Amateur Professional
Reminds me a bit of the Binder Dragonfly in the midspan, looks interesting.

#### jqavins

##### Joseph Avins
TRF Supporter
With the two sets of fins it looks more dragonflylike than the Binder version. Of course, on a dragonfly the wins are up front where most of the mass is, but whadaya gonna do?

Would you realize it with swept elliptical rear fins, rather than the swept trapezoids that are so much easier to put into OR?

##### Well-Known Member
TRF Supporter
With the two sets of fins it looks more dragonflylike than the Binder version. Of course, on a dragonfly the wins are up front where most of the mass is, but whadaya gonna do?

Would you realize it with swept elliptical rear fins, rather than the swept trapezoids that are so much easier to put into OR?
Dragonfly was kind of the look I was going for. I would have liked to sweep the elliptical fins forward a bit, but hard to do on OR. I could also reverse them and put the trapezoidal in front and the elliptical in back. Of course, outside of OR I can do anything I want. Two sets of elliptical might be better.

##### Well-Known Member
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Getting away from the dragonfly look, but staying with the two sets of fins idea......

#### XrayLizard

##### Well-Known Member
Winter is building time!

#### jqavins

##### Joseph Avins
TRF Supporter
I would have liked to sweep the elliptical fins forward a bit, but hard to do on OR.
Does OR give you the ability to define a set of fins by a list of points? I think t does, based on stuff I've seen from others here. Does it give you the ability to import said list of points from another source? If so, one could compute the points for a swept ellipse in another program, most likely Excel or LibreCalc. I do that in RockSim sometimes, but you have to hack the .RKT file in a word processor. I opened the .ork file a few posts back in Notepad, and it doesn't look like it would be hackable the way .rkt files are.

#### JoePfeiffer

##### Well-Known Member
Does OR give you the ability to define a set of fins by a list of points? I think t does, based on stuff I've seen from others here. Does it give you the ability to import said list of points from another source? If so, one could compute the points for a swept ellipse in another program, most likely Excel or LibreCalc. I do that in RockSim sometimes, but you have to hack the .RKT file in a word processor. I opened the .ork file a few posts back in Notepad, and it doesn't look like it would be hackable the way .rkt files are.
It does have "freeform" fins defined by a series of points. It doesn't have a way to import them from another program. The file format is just zip-compressed XML, so you could unzip it and edit it in a text editor, but the freeform fin editor ought to work well enough you don't need to.

#### jqavins

##### Joseph Avins
TRF Supporter
When I do this with RS is when I want to use dozens of points. The trouble of typing them all, then finding and correcting the typos, is less than the trouble of editing the file.

#### neil_w

##### Working on 20K
TRF Supporter
OR can import images and it will convert them to freeform fins. That's the way to do stuff like this. You only need to be able to create the image in a paint program or the like.

#### Scott_650

##### Well-Known Member
OR can import images and it will convert them to freeform fins. That's the way to do stuff like this. You only need to be able to create the image in a paint program or the like.
Which file format? .BMP?

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#### K'Tesh

##### OpenRocket Chuck Norris
TRF Supporter
For more step by step instructions, you can see my tutorial thread...

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##### Well-Known Member
TRF Supporter
OR can import images and it will convert them to freeform fins. That's the way to do stuff like this. You only need to be able to create the image in a paint program or the like.
I think that's beyond my computer skills right now, but I need to play with it.

##### Well-Known Member
TRF Supporter
I'm looking at buying a drill press and a lathe. I think one of those laser cutters for making fins is out of my reach.
I'm probably crazy for even thinking about the drill press and lathe. But I'm hoping it allows me a lot of design freedom.

#### Greg Furtman

##### Well-Known Member
TRF Supporter
I'm looking at buying a drill press and a lathe. I think one of those laser cutters for making fins is out of my reach.
I'm probably crazy for even thinking about the drill press and lathe. But I'm hoping it allows me a lot of design freedom.
@Senior Space Cadet , I have a Ryobi scroll saw that I use for cutting fins and centering rings. It works well. Recently I have seen many used wood lathes and scroll saws on my Facebook local Buy & Sell page, some of them very reasonably priced. Like a Delta scroll saw for $20. Needs a little clean up and TLC but the old ones are pretty much all cast iron. I've also seen Rockwell wood lathes like mine going for$100.

#### jqavins

##### Joseph Avins
TRF Supporter
OR can import images and it will convert them to freeform fins. That's the way to do stuff like this. You only need to be able to create the image in a paint program or the like.
Oh dang! that's the best reason I've heard to get friendly with OR.