# Circuits as fins?

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#### mooffle

##### Well-Known Member
TRF Supporter
I have a surplus of circuit boards and RAM sticks, I thought it would be cool to chop them up and use for fins, maybe even as UFO sides.
However NAR safety code says no metal for fins. my immediate thought is that this should be ok since the base is fiberglass but then what about the lead/copper content? Would that make it too heavy or too hard a material for rockets?

#### Bill S

##### Well-Known Member
Maybe not as good, but could you take a picture of the circuit boards, and print them on label adhesive paper and put that on the balsa fins?

#### Funkworks

##### Well-Known Member
Doesn’t seem very aerodynamic. Unless you can ensure symmetry, rocket might spin, spiral or curve.

No comment on the NAR/legal side. I leave that to RSOs.

#### mooffle

##### Well-Known Member
TRF Supporter
I suppose a scan would do, but I work in IT and have enough of the darn things to side my home with them. No one want 256 mb sticks anymore. I'd rather use the real deal.

Aerodynamics shouldn't be an issue but I'll keep it in mind. I'd be using them in pairs so spin should either be constant from all opposing fins or both sides of the chips will be the same and no spin will be induced. I like to launch mostly A's and B's in my park right now so if it only goes 100ft up its still a win.

#### dhbarr

##### Amateur Professional
Build a desoldering oven out of a toaster oven. Presto, free very high quality fiberglass with some holes in it! Nobody's going to mind the copper foil layers.

#### mooffle

##### Well-Known Member
TRF Supporter
Build a desoldering oven out of a toaster oven. Presto, free very high quality fiberglass with some holes in it! Nobody's going to mind the copper foil layers.
I can't tell if this is genius or insanity.

#### BABAR

##### Builds Rockets for NASA
TRF Supporter
I have a surplus of circuit boards and RAM sticks, I thought it would be cool to chop them up and use for fins, maybe even as UFO sides.
However NAR safety code says no metal for fins. my immediate thought is that this should be ok since the base is fiberglass but then what about the lead/copper content? Would that make it too heavy or too hard a material for rockets?
Don’t see why it wouldn’t work.

It’ll be heavy, draggy, meaning you’ll need nose weight and a bigger motor.

It will make a unique rocket. The extra time it takes to construct may or may not be worth the time saved by standard building. If it “sparks” your fancy, go for it.

#### rharshberger

##### Well-Known Member
I can't tell if this is genius or insanity.
Its DHBARR.....check out some of his builds...you decide!
Actually its a really good suggestion, and circut board fins would have a certain "cool factor".

#### dhbarr

##### Amateur Professional
Its DHBARR.....check out some of his builds...you decide!
Actually its a really good suggestion, and circut board fins would have a certain "cool factor".
I have lots of ideas. Sometimes one of them is good.

#### PatD

##### Well-Known Member
TRF Supporter
Draw patterns of your choice on the circuit boards with a resist pen and etch it. Lets you reduce rear weight and after you neverdull polish the remnants and clearcoat it. Oh that is an idea. I have some 1/8 double sided copper boards. The sky is the limit for designs.

#### OverTheTop

##### Well-Known Member
I like the idea. I don't think the RSO would have any trouble with this. As others have said it will be draggy and craggy and need some nose weight.

Very ingenious!

#### TXWalker

##### Member
Recycled PCB for fiberglass fins. Just filled the holes and sanded smooth. I did an extra layer of fiberglass tip to tip after mounting to the airframe. I’ve done this on other rockets. Super strong.

#### JoePfeiffer

##### Well-Known Member
Not enough metal to worry about -- less than an eye bolt, and in a form that isn't going to increase damage if the rocket hits something (that and shrapnel after a CATO being the reasons for the metal prohibition). As others have said, heavy so watch your CG and draggy, but a nice cyberpunk esthetic. I'd probably only use them on a rocket with a fiberglass airframe.

#### jrap330

##### Retired Engineer, NAR # 76940
TRF Supporter
I have a surplus of circuit boards and RAM sticks, I thought it would be cool to chop them up and use for fins, maybe even as UFO sides.
However NAR safety code says no metal for fins. my immediate thought is that this should be ok since the base is fiberglass but then what about the lead/copper content? Would that make it too heavy or too hard a material for rockets?
Someone years ago did this, not sure if model or MPR or HPR. Was done 15-20 years ago. Also did it with old CDs....

#### mooffle

##### Well-Known Member
TRF Supporter
Ooh, maybe a cd as the hub with the RAM sticks as my drag component on a UFO. Or 3.5 floppies... if they can hold together.

#### Dugway

##### Well-Known Member
I used CD halves as fins on a competition Super Roc. They aren't as strong as you might think, one shattered on landing after a nominal recovery.

#### Rktman

##### Eric
I think it's a brilliant idea, especially considering you're goal isn't altitude/performance but rather the visual impact. As others have noted, you need to pay special attention to stability, but you get to recycle and put those circuit boards to good use, they're plenty strong for LPR use (probably even for midpower rockets) and the coolness factor is off the charts, especially for UFOs/saucers as you mentioned. It definitely would make for some truly unique designs.

#### ThirstyBarbarian

##### Well-Known Member
TRF Supporter
There is a guy in one of my clubs who has a rocket with circuit board fins.

#### mooffle

##### Well-Known Member
TRF Supporter
Snagged these from work, and they were in different colors too! I'm definitely leaning towards a saucer with these layered as the sides. Thanks for the encouragement and ideas everyone.

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#### OverTheTop

##### Well-Known Member
Looking forward to seeing whatever it is fly!

#### vcp

TRF Supporter
I have stacks of old blank PCB's that are about 4 inches square. I keep them around for windshield ice scrapers. Each board effectively has eight very sharp fiberglass edges and you can flex the board to conform to any mild curve. The cost is zero (originally ~$50 each) and I often give them away when I see someone scraping a windshield with a credit card. #### Greg Furtman ##### Well-Known Member TRF Supporter I have stacks of old blank PCB's that are about 4 inches square. I keep them around for windshield ice scrapers. Each board effectively has eight very sharp fiberglass edges and you can flex the board to conform to any mild curve. The cost is zero (originally ~$50 each) and I often give them away when I see someone scraping a windshield with a credit card.
@vcp Micron's headquarters is in Boise isn't it? Been buying their memory for years now because I found out that they had donated a large amount of memory to SETI in its early years.

#### mooffle

##### Well-Known Member
TRF Supporter
Ok, so I finally got around to putting this concept into play.
The final product will be a flying saucer with a good bit of induced spin, probably on a C6-0. The blue sticks will be glued to the fan blades matching their cant for drag/spin stabilization. I'm undecided if I'll use the green cut pieces here for added strength or save them for a 4fnc rocket. I also got some Windows 2000 floppy disks that would be fun to incorporate somehow but that will likely throw the mass over what an estes 18mm will do.
The hub is a 3 bladed hp server fan. everything will be computer parts except the motor mount.

The next question is; how on earth to I check this thing for stability? OR or Rocksim are out... would a swing test even be useful for such a weird shape?

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#### vcp

##### Well-Known Member
TRF Supporter
@vcp Micron's headquarters is in Boise isn't it? Been buying their memory for years now because I found out that they had donated a large amount of memory to SETI in its early years.
It's funny I haven't heard a word about Micron in years - I couldn't tell you if they're still there or not.

#### Greg Furtman

##### Well-Known Member
TRF Supporter
It's funny I haven't heard a word about Micron in years - I couldn't tell you if they're still there or not.
Micron is still in business. Crucial is their memory company. Crucial also sells SSDs. And Micron is manufacturing memory & storage memory for other companies. Plus they do a lot of R&D.

##### Well-Known Member
TRF Supporter
I have a surplus of circuit boards and RAM sticks, I thought it would be cool to chop them up and use for fins, maybe even as UFO sides.
However NAR safety code says no metal for fins. my immediate thought is that this should be ok since the base is fiberglass but then what about the lead/copper content? Would that make it too heavy or too hard a material for rockets?
It will be perfectly fine. Metal content is minimal, and modern RAM sticks are fairly low-profile.
The fins will not be optimally aerodynamic, thus they will induce more drag than you would expect from a regular fin.

Fins don't have to be perfectly smooth and aerodynamic to be effective. The rocket may not fly as high with "bumpy" fins full of holes, but it will be stable.
If modeling in OR, just enter the actual weight of each fin, and the average thickness across all cross sections.

The final product will be a flying saucer [...] how on earth to I check this thing for stability? OR or Rocksim are out...

#### vcp

##### Well-Known Member
TRF Supporter
Micron is still in business. Crucial is their memory company. Crucial also sells SSDs. And Micron is manufacturing memory & storage memory for other companies. Plus they do a lot of R&D.
Yeah, that was sort of tongue-in-cheek; I worked there 22 years. Designed a number of Micron products, spent most time designing dram testers, and product EMC testing. Behind me now.

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#### mooffle

##### Well-Known Member
TRF Supporter
Those parts were the hardest thing I've ever tried to glue in my life. Pretty sure sure the joints will fail...
I did not think through my clamping process with the curved surfaces.

#### mooffle

##### Well-Known Member
TRF Supporter
As for OR I suppose I can run them as highly canted fins. I know there was a 'trick' method with adding a tailcone that I will look into.