The fabric weighs 145g/sm. 12 layers. Should be about 1/16" wall.
Carbon Prepreg Airframe build for the Loki 54/4000 - Fins Attached
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Wow thats a lightweight fabric. Very pretty UNI too.
Alexander Solis
Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
Thanks, I like it too.
Here are some after-cure pictures.
This is one with the spiral heat shrink tape still in place.
Here's a couple with the tape removed. And the ridges the tape left behind.
Some cured epoxy also got underneath the mylar somehow. I'm dealing with that now, should have taped the ends of the mylar. /facepalm
So it was relatively easy to get the tube off the mandrel after a stay in the freezer. The tube is very strong, probably too strong. It's right at .060" wall thickness, and that's with the Mylar. Unfortunately the Mylar seems to be part of the layup.
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Did you use a mylar that is rated for high temps?
It could be that the mylar melted to your fabric and not the epoxy sticking to it.
Other then that it looks great! Do you have a weight for the tube?
It could be that the mylar melted to your fabric and not the epoxy sticking to it.
Other then that it looks great! Do you have a weight for the tube?
I would try a tighter overlap on your shrink tape next time.
Other than that look like the resin still flowed pretty well. When you trim the ends you can get an idea of how well it compacted. Did you release the mylar? You might have some luck using a pressure washer to get the mylar out.
Strong work.
Other than that look like the resin still flowed pretty well. When you trim the ends you can get an idea of how well it compacted. Did you release the mylar? You might have some luck using a pressure washer to get the mylar out.
Strong work.
Thanks for the compliments and suggestions, guys.
Kyle, as far as I can tell, there isn't a high temp Mylar, exactly. Tfish suggested the Mylar because of it's thickness compared to the thin high-temp film I was going to use. The thin high-temp would have likely wrinkled under the lay-up and caused nightmares when removing the tube from the mandrel. I used a "high-temp wax" on the Mylar. But I now I feel silly using "high-temp" and "wax" in the same sentence. I may try Freekote next time on the mylar. The Mylar became brittle in the heat. It definitely changed properties, but it also released from the aluminum just fine.
Flynfrog, the tape spacing you have looks like it is the key to a smooth tube. I'll try that next time for sure.
I'll cut the ends off after it cools off outside a bit. It has that nice "ring" that high quality composite parts have. That's a good sign...
Kyle, as far as I can tell, there isn't a high temp Mylar, exactly. Tfish suggested the Mylar because of it's thickness compared to the thin high-temp film I was going to use. The thin high-temp would have likely wrinkled under the lay-up and caused nightmares when removing the tube from the mandrel. I used a "high-temp wax" on the Mylar. But I now I feel silly using "high-temp" and "wax" in the same sentence. I may try Freekote next time on the mylar. The Mylar became brittle in the heat. It definitely changed properties, but it also released from the aluminum just fine.
Flynfrog, the tape spacing you have looks like it is the key to a smooth tube. I'll try that next time for sure.
I'll cut the ends off after it cools off outside a bit. It has that nice "ring" that high quality composite parts have. That's a good sign...
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I have found this while browsing McMaster Carr one day its a High Temperature PET Film.
Item # 7594T11
Search that on McMaster Carr and see if it fits your needs. It can be used up to 400*F.
Item # 7594T11
Search that on McMaster Carr and see if it fits your needs. It can be used up to 400*F.
Aksrockets
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Why use mylar at all? Shrink tape can be used by itself as the release layer on tubing. Its meant to squeeze excess resin out, but it cant do it with the mylar there.
Very very intereted with this build. Carry on!
Alex
Very very intereted with this build. Carry on!
Alex
The Mylar was on the inner diameter to prevent it from sticking to the mandrel. The tape I have is treated with a release on one side. I had thought about using Mylar under the tape next time to eliminate the ridges ala Oberth as there shouldn't be any extra resin to squeeze out of the prepreg. But I like Flynfrog's overlap and I'll try that next.
Kyle I had seen that stuff on McMaster as well, but I'd rather not spend that much if I can avoid it.
Maybe I don't need Mylar on the ID at all? just Frekote. hmm....
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I agree it is rather pricey just something I noticed that I wanted to point out.
I'll probably spend the $80 looking for alternatives before breaking down and buying that. It is my way. My wife loves it...
You shouldn't need the mylar for release-- just do a good job with the mold release (or wax) and it should pop off the mandrel no problem once it's cool. If the mylar is for tolerancing, does the mandrel expand enough at the cure temperature to do the job on its own?
Looks great, though!
Looks great, though!
Cut end, kinda rough but the compaction looks good.
10" long, 3.5oz
10" long, 3.5oz
Lovely wall thickness. The compaction sure did a good job.
Alexander Solis
Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
Alexander Solis
Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
Ordered some of this stuff today to try instead of the Mylar. No release ply seems a little scary in this case, but I have done it for many a nosecone and R/C sailplane fuselage mold.
https://www.aircraftspruce.com/catalog/cspages/lpsSiliconeMold.php
https://www.aircraftspruce.com/catalog/cspages/lpsSiliconeMold.php
Silicone is pretty scary for anything you are going to have to bond and paint later. I wouldn't spray that any where near where you plan to paint or bond ever. I would use free kote or safe lease even johnson paste wax works pretty well.
Dangit! I think I knew that. Maybe you had mentioned it before. For the high temperature cure Safelease sounded like the best bet, but it was a large quantity and pricey. Maybe I can find someone who wants to sell a small quantity. Got any?
But looking into the Frekote just now I seem to be mistaken that it wont handle the high temps.
And when you say Johnson Past wax, you mean this stuff? https://www.homedepot.com/p/SC-Johnson-16-oz-Fine-Paste-Wood-Wax-00203/100154748
I have Partall #2, but I didn't think that was appropriate for the temperature.
Dangit! I think I knew that. Maybe you had mentioned it before. For the high temperature cure Safelease sounded like the best bet, but it was a large quantity and pricey. Maybe I can find someone who wants to sell a small quantity. Got any?
But looking into the Frekote just now I seem to be mistaken that it wont handle the high temps.
And when you say Johnson Past wax, you mean this stuff? https://www.homedepot.com/p/SC-Johnson-16-oz-Fine-Paste-Wood-Wax-00203/100154748
I have Partall #2, but I didn't think that was appropriate for the temperature.
I am pretty sure I have used that paste wax over 250F but its back in the hazy time part of my brain.
Freekote comes in lots of flavors and some are on amazon
https://www.henkelna.com/us/content_data/307199_LT4831_Frekote_Guide_Final_LR202359.pdf
you might be able to find some watershield
https://www.chemtrend.com/our_brands/zyvax/release_agents
It never hurts at ask for a sample if you can find a local rep.
I would be more concerned about fitting motors into your finished case. I did a layer of peel ply wrap on my 54mm airframe to make sure I could get CTI motors in as they bulge at the front edge.
Cancelled the Aircraft Spruce order (you can do that online, kinda cool) and ordered an aerosol can of Frekote 700nc from ACP.
As far as the motor fitting, there won't ever be a CTI motor in this rocket. I like CTI quite a lot, but this is purpose built for the Loki 54/4000. The test I made fits fine, even with the Mylar still inside it. As far as I can tell that mylar is now one with the ID of that tube. I could get the line of flash tape to pull up, however.
Perhaps one of Dunstone's non-heat shrink High temp release tapes could work to prevent sticking to the ID of the tube.
https://www.shrinktape.com/products/non-shrink-tape/contour-tape.aspx
Since your making a 54mm tube spiral wrapping should not be a problem.
Alexander Solis
Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
https://www.shrinktape.com/products/non-shrink-tape/contour-tape.aspx
Since your making a 54mm tube spiral wrapping should not be a problem.
Alexander Solis
Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
The Frekote should work for you and the temperatures that you expect. I believe it was the 770nc, that we used recently, and it worked well for autoclave cured parts. When it came to the demoulding step, a reasonable nice aluminum mandrel worked better than a very nice steel mandrel - so I think your chances are good. My experience at this point is very anecdotical, though.
Reinhard
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That's good to hear. Getting excited for the next practice tube. I'm also spending a little time getting the big oven ready for the real deal.
I made a second practice tube tonight with tighter shrink tape spacing and Frekote 700-NC as the release.
First off, the Frekote worked great. Very impressed! I was able to start sliding the tube off the mandrel before I even chilled it. Pretty cool. The tighter spacing on the tape worked better, but I still have some ridges I need to take care of somehow. Here's some pics-
New tube in front
I going to have to ponder what to do about the ridge situation.
First off, the Frekote worked great. Very impressed! I was able to start sliding the tube off the mandrel before I even chilled it. Pretty cool. The tighter spacing on the tape worked better, but I still have some ridges I need to take care of somehow. Here's some pics-
New tube in front
I going to have to ponder what to do about the ridge situation.
Much more nicer indeed. The ridges are going to be normal thanks to the heat shrink tape's thickness. Keep up the good work
Aksrockets
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You could incorperate a fiberglass veil layer into the tube and sand into that. That way you wont damage your carbon.
Alex
Alex
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+1. If you do not have access to a lathe you could even sand the ridges down manually, that of course is assuming that the ridges are in fact epoxy.
So, it's September now, how about a progress report? Is this rocket gonna be ready for Octoberfest?
I did some shopping at Scott's booth at Airfest, couldn't pass up this photo opp:
Lot's of MD 54mm rockets to check out, here's one that flew to 33k:
Mach 3 takes it's toll on the paint:
Thanks to Kyle for sharing his build with me, gave me some great ideas for future builds.
I did some shopping at Scott's booth at Airfest, couldn't pass up this photo opp:
Lot's of MD 54mm rockets to check out, here's one that flew to 33k:
Mach 3 takes it's toll on the paint:
Thanks to Kyle for sharing his build with me, gave me some great ideas for future builds.
