Finishing fiber fins?

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Mugs914

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The Excalibur was one of the rockets I always wanted as a kid, but none of the shops in our area carried Centuri stuff so it was forever on the wish list. Well, I just got the Semroc version from eRockets and it is great. Still a very cool looking bird!

Like a lot of Centuri kits from the time it uses fiber (cardboard) fins, but this is the first time I have dealt with them. Do you guys have any tips for finishing fiber fins?

Thanks!

Mike
 

mccordmw

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Look up Aqua Resin. It does wonders for cardboard. Cosplay people use it to harden their cardboard costumes.
You can also paint thin CA on the surface of the fin. Not as strong as a good penetrating resin. I looked at the Excalibur just now. Those bottom fins seem long relative to the <1" body.
 
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Micromeister

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Depending on the thickness of the cardstock or cardboard there are at least two other ways to harden them. First: good Ol'e medium CA. soaked into the fiberboard type fins. If thinner cardstock or pressed cardboard I usually apply a soaking coat of min-wax wood hardner.

Once dry either sands like styrene plastic using 240 and 320 grit sandpaper. then prime and paint as you would for any other rocket.

One word of warning: by hardening cardstock it is a bit more subject to cracking and breaking on impact landings. if you intend to fly you models with streamer only it is NOT necessary to harden fiberboard fins.

I'm not sure if the Excaliber you speak of is from the Space pirates series or not, along with the dragon ship they were a pair of "Must Have" models from the golden age of rocketry. This Old brain sometimes confuses the really Good rocket designs between Centuri and Estes. That Said these early really KEWL designs had to be downscaled to fly on Micro Maxx motors. and so they both were:)

Like you in my early rocket years I LOVED all the Centuri designs. One of my all time favorites is the Laser-X which has a long cardstock interstage shroud my 1971 original and my clone 1: 1.41 Upscale use the same CA Soaked cardstock shroud. In 1990 I found & purchased a 1968 original Centuri kit, and built it anyway. about 10years later I did a 3X Upscale with a BT-101 lower stage. The Upscale is a 3- D12 clustered lower stage with and 18mm (Usually a B6 or C6) upper stage. Photos below show the orignal 1968 model and the 3X -3D Upscale side by side. the Main fins and interstage are actually 3/64th" 3ply aircraft plywood. fins are over a 1/4" foamcore base. in recent years I've switched almost entirely to building and flying ALL my favorite models in Micro Maxx power scale. You guessed it: a 2x downscale Laser-X powered by a single MMX-I motor was added to the fleet.

Centuri had a bunch of Cardstock and-or fibre board models. The X-24 bug BG, The Vulcan, Centuri UFO were all entirely cardstock. Some parts required stiffening while others remained untreated only primer and paint or marker as usual.

Laser-X-1-sm_1st Fleet Centuri's best b&w_04-03-71.jpg


037-sm_ Laser-X 1.41 D Upscale_10-27-89.jpg


088-sm_Laser-X (centuri 1968)_11-15-90.jpg


MM 373b_MM Excalibur & DragonShip-7 Side-Rear_04-18-11.JPG


MM 229b2-sm_Laser-X_MidFlight_07-07-01.jpg
 
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Mugs914

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Thanks for the info guys. My usual finish on small balsa fins is to harden them up with thin CA, so I think I'll try that on the fiber fins. The Aqua Resin sounds interesting too. Is that a Michael's/Hobby Lobby thing or does it come a more specialized source?

This is the Excalibur I am talking about, John.

Excalibur1.jpg

Not quite as cool as the Space Pirate version in your picture, but you are right, those are both must-haves!

The Laser-X is also on my old (unfulfilled) wish list. I'm planning on getting the Semroc version at some point and I might have to do your three D powered upscale version too. That is a beautiful piece of work.

Mike
 

Mugs914

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So I did the thin CA treatment on the fiber fins and it really came out great. I was impressed with how much they firmed up once everything cured (I don't use any accelerator when I'm using CA as a filler), came out like a plastic fin.

I have to get the motor mount glued in, then its painting time. I'm going to go with the original pale blue/green like the pic above and in the original catalog pic. The Semroc decals are red, so those might not work with the green color, but they'll get used somewhere...

Thanks for the info guys!

Mike
 
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