Enceladus: A 75mm Minimum Diameter XX Phenolic Build

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Cherrywaves89

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First things first. She has already flown, and this is a sort of retroactive thread. I always document a lot of the build process, so I might as well put it somewhere where it can be appreciated hopefully. I’ll save the flight results for the end.

Let’s dive right in.

Enceladus is a fairly modified Mac Performance Zodiac kit. She came with a 54mm motor mount, but when the fin slots came damaged from shipping, I asked MP to just send me the booster without them, and we will just go with my favorite kind of rocket. Minimum Diameter! Booster was sent over free of charge without fin slots, and I got straight to work.

Fins were tacked on using an epoxy comparable to Loctite EA 120-HP, and held in place using a printed jig I have developed over the last few years. View attachment 650797
 
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I’m attempting to make the photos visible without having to click on a link, so if anyone has any guidance, that would be much appreciated. Not sure what to do there.

Once the fins were nice and sanded, fin root tacked, and sat overnight, I came back to a pretty solid bond, and it was the time for fillets.
 

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Followed up the smaller fillets with a larger Proline 4500 fillet. I like to use this epoxy as an aesthetic layer because it’s much easier to sand down the road. We will be doing a layer of carbon later, so I like to have a little control over the shape.
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Curious Nick, what do you do to prep the initial fillet prior to laying down the 4500? I assume you scuff the surface of that 'inner fillet', or do you lay down the 'outer' fillet before the inner has fully cured, so there is some chemical bonding between the two?
 
Looks like the body is a cloth phenolic (probably L or LE). It will survive flight stresses well but it's brittle. Less than optimal recovery or even falling over onto concrete will likely crack it. Tried it ~30 years ago and it shattered on a less then optimal recovery when the bonus delay was about 5 sec late. Broken other pieces falling over onto concrete. It is good for outboard motor tubes as it doesn't burn up from the center motor when you don't use all the outboards. PML phenolic works well for this application also but it has the same problems as the LE phenolic.
 
Curious Nick, what do you do to prep the initial fillet prior to laying down the 4500? I assume you scuff the surface of that 'inner fillet', or do you lay down the 'outer' fillet before the inner has fully cured, so there is some chemical bonding between the two?
Yes. I hit the cured first fillet with some 180 grit, then wipe clean with a lint free cloth and some acetone. This was very much experimental, but with the layer of carbon, I’m not super worried about it.
 
Looks like the body is a cloth phenolic (probably L or LE). It will survive flight stresses well but it's brittle. Less than optimal recovery or even falling over onto concrete will likely crack it. Tried it ~30 years ago and it shattered on a less then optimal recovery when the bonus delay was about 5 sec late. Broken other pieces falling over onto concrete. It is good for outboard motor tubes as it doesn't burn up from the center motor when you don't use all the outboards. PML phenolic works well for this application also but it has the same problems as the LE phenolic.
This is actually XX phenolic. You can literally beat it on concrete with full force without issue. The TAP member Conway Stevens has a video of himself using it as a baseball bat.
 
Measured and cut a piece of 3k carbon to fit just proud of the fins in all directions. (3M spray adhesive on the last 1/16” helps keep the carbon from fraying) Then using West Systems w/206 slow hardener, the airframe was wetted out, carbon impregnated, and then carefully layed onto the fins. Using a brush, the carbon and airframe were mated together using a stippling method as I’ve heard it called. To finish it off, the excess resin was pulled off with a foam brush to avoid any loose brush hairs. A layer of peel ply was added at the end and the assembly was tucked in for a good nights rest. This process was repeated twice more, and then we end up with our next post.
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Looks like the body is a cloth phenolic (probably L or LE). It will survive flight stresses well but it's brittle. Less than optimal recovery or even falling over onto concrete will likely crack it. Tried it ~30 years ago and it shattered on a less then optimal recovery when the bonus delay was about 5 sec late. Broken other pieces falling over onto concrete. It is good for outboard motor tubes as it doesn't burn up from the center motor when you don't use all the outboards. PML phenolic works well for this application also but it has the same problems as the LE phenolic.
What a difference 30 years makes ;^)
 
. . .and here you have it! The rocket is completed!

*Sanding gods begin laughing like the villain in a Batman movie *

• Okay, so I lied. After you spend 3-4 nights precisely cutting the carbon, fighting the fraying like some kind of quasi crochet champion, feverishly trying to outpace the curing time, then patiently waiting for the curing to complete, the real work can now begin. Braden Carlson at Rocket Vlogs has a pretty good resource on YouTube that depicts a young boy beginning the sanding process, and a grown man emerging at the end. Check it out.

• With some decent surface prep, a little creativity and planning, and some luck, you can actually reduce the sanding by a little, but not much.View attachment IMG_0761.jpeg
 
Here is the plan for the rest of the build. Obviously minimum diameter, wanted to give that booster ALLLL THE ROOM for motors, delete the switch band, go with a Zipperless coupler, and put a camera/tracker in the nose. This design calls for a lot of stuff crammed into the payload tube as you can see.
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Here is a top down look at the Zipperless coupler. I’ve never seen anyone do this exactly as I have, so I will do my best to explain.

• This Zipperless coupler also acts as motor retention. The stop nut pictured here holds a piece of threaded rod that can be easily removed and cut/lengthened depending on the motor that is flying on a given day.

• Used a piece of Kevlar with two spliced loops at the bottom as a connection point for the drogue, connected by a quick link at the bottom (see next photo). This entire coupler assembly sits atop a tiny piece of coupler glued into the airframe.

• Printed 4 pieces of protective inserts to avoid cutting the Kevlar.
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As stated before, the payload section will be an ambitious design for me. Holding two parachutes, Nomex, 80’ of shock cord, quick links, swivels, charges, half of the NC coupler, half of the Zipperless coupler, and the Av-Bay inside of 20”.

• I nearly fried my biological processor trying to will this into existence. I don't tie knots in the shock cord anyways, but had I done so, I’m sure this wouldn’t have worked.

• Electronics include an Eggtimer Quark, a Featherweight Blue Raven, powered by 9v, and switched by screw switches. Future designs will use LiPo batteries. I have read recently that 9v may have issues under high G loads.

• This sled is inside of a 3.5” coupler. The whole bay slides down the tube, and seats on another small piece of glued coupler so as not to rely on just the M3 screws during boost.

• Needless to say, this will require the smallest Av-Bay I have ever personally made. Here is what that looks like.
 

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The camera bay is a design I’ve been tuning for some time now, and this is what I’ve landed on.

• A drone camera with a spring loaded lens, that pops out of the bay and sits perfectly flush with the airframe. I’ve never been a huge fan of a glass window as if you’re looking out of a tunnel, and this is my attempt at avoiding that.

• Assembly is retained again with M3 screws in the NC, and powered by a 2s LiPo. These cameras are very difficult to work with in the summer due to overheating, but you can get a little more time on the pad by using a little thermal epoxy and bonding a heat sink directly to the chip.

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