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Clear Plastic HPR fins?

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PunkRocketScience

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Hey all-

The PRS build team is working on a scale project for next year's Plaster Blaster that won't be quite stable without some additional fins. Not wanting to mess up the look of the rocket with non-scale fins, we would like to use clear plastic ones.

Do any of you have a particular type of material you would recommend? After seeing Paul Snow's Delta lose it's plexiglass fins last year at PB, we just want to make sure we don't have a similar occurrence...
 
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MarkII

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Do any of you have a particular type of material you would recommend? After seeing Paul Snow's Delta loose it's plexiglass fins last year at PB, we just want to make sure we don't have a similar occurance...
Loose or lose? Did he lose them because they were loose? Did it cause the rocket to be loost or did it cause it to be lost?

MarkII
 
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dixontj93060

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I have had success with Lexan which I purchased at Lowes. I used it on my 5" diameter Crayon rocket which took a "fluttering" fall (parachute didn't fully deploy) and landed hard on the fins with no problem.
 

rstaff3

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You gotta go with Lexan. You can likely get thicker stock at a plastics supply house than the stuff you get at hardware stores.
 

jadebox

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Lexan is definitely the way to go. It doesn't shatter and flexes well without breaking. It's not expensive, and it's easy to work with. I bought my sheets from an online source called estreetplastics.

I used Lexan fins for my "Tikva" rocket. I cut the fins out by tack gluing togetehr the Lexan sheets (with the protective paper covering in place). Then I cut all four fins out at the same time with a jig saw. I used a belt sander on the edges to clean up the shape. Then I used a sandling block with finer and finer sandpaper on the edges to smooth them.


You can't really glue Lexan to anything, so I bolted wooden strips to the root edges of the fins. The wood strips were glued to the motor tube and screwed to the centering rings. The whole assembly slid into a slotted body tube.


I made the fins too large on purpose in order to try to keep my camera rocket from rolling. It worked well on the first few flights. Then I tried using a more powerful motor ...


The fins were a bit too large and thin to hold up to the K motor. I used the thinner Lexan just because I had it. Thicker Lexan would have probably held up, but would have been heavier. I probably should have used thicker Lexan and smaller fins. Anyway, I'm rebuilding the booster with G10 fins right now.

BTW, I'd use Lexan for fins on more rockets if you could easily glue it to other materials, if it weren't so heavy, and if it wouldn't scratch so easily.

-- Roger
 
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MarkII

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I made the fins too large on purpose in order to try to keep my camera rocket from rolling. It worked well on the first few flights. Then I tried using a more powerful motor ...
Oh, man... check out the fin flutter! :eek:


BTW, I'd use Lexan for fins on more rockets if you could easily glue it to other materials, if it weren't so heavy, and if it wouldn't scratch so easily.

-- Roger
Well, you could glue a plastic coupler inside the fin can, in between the centering rings. Then you would carefully cut out slots in the body tube without cutting through the coupler underneath. Then you would use clear butyrate dope to "bond" the fins to the underlying coup... Oh, wait, that's been done... :rolleyes:

MarkII
 

UPscaler

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I agree with everyone else. Use lexan..It is fairly inexpensive and is available at most home improvment stores.
 

PunkRocketScience

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Loose or lose? Did he lose them because they were loose? Did it cause the rocket to be loost or did it cause it to be lost?

MarkII
Thanks for the grammar lesson Mark... You failed to point out that I misspelled "occurance" as well thought. Guess I shouldn't post when I'm tired and in a hurry....
 

MarkII

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Thanks for the grammar lesson Mark... You failed to point out that I misspelled "occurance" as well thought. Guess I shouldn't post when I'm tired and in a hurry....
I didn't want to pile on... ;) Yours was in all likelihood just a typo, which, of course, we have all done. As a less-than proficient four-fingered typist with a tendency to hit the gap between the keys, I have certainly posted my share of them. In recent years, though, I have seen that error so often that I have to wonder whether anyone even knows that there is a difference between the two words anymore. Spelling checkers actually contribute to the problem, too, because they show "loose" as being correctly spelled. I don't point out errors in other people's posts (this is my very first one) but that error has reached such epidemic proportions that I finally overcame my reticence (or discretion) and spoke up. I apologize for making you the victim. In your case, it was probably just an innocent typo.

Now back to the fin discussion....

MarkII
(former English major and reluctant pedant)
 

Micromeister

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I don't fly HPR: but I do fly a lot of mid and cluster models with Clear fins.

the are all clear Polycarbonate, (Lexan is only one of the brand names). it's is the best choice for fins in Model rocetry regardless of power class. just be very very careful you are getting a polycarbonate not a modified acrylic which is what many of the home improvement stores are selling. it is NOT polycarbonate and IS NOT suitable for use on rockets. if you can't cold fold the plastic you have 90° without breaking it is not polycarbonate.
hope this helps a little.

Ps: Tech-Tip-017 working with Plastics available for download from the narhams.org library may be worth a few minutes.

Plastics-5a_Polycarbonates, Weld-on-16 & epoxy rivets_01-02-10.JPG


Plastics-5b_Best Polycarb-Polycarb adhesive & 2 joints_01-02-10.jpg


Plastics-5c_Polycarb-Cardboard epoxy rivet joining_01-02-10.JPG


Plastics-6e1_Best polycarb-anything epoxy rivet joint_01-02-10.jpg


Plastics-6e2_Polycarb-cardboard epoxy rivet & fillet joint_01-02-10.JPG
 
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