Aurora V2 38mm MD

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conman13

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Well, people were right when they say you never actual lose the rocketry bug... It's been about 4 years since I left the hobby before I left for my freshman year of college. I had picked up working on cars as a hobby right before I stopped, but now that my car is done the idea of getting back into rocketry has been in the back of my mind.

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Now that I'm 20 and can actually handle the motors and get the proper certifications as well as not needing to worry about scaring girls off with the talk of flying tubes I figured it was about time I start a new project, rather revise and rebuild an old rocket I had built, Aurora. I've revised the old file in order to make the rocket more practical for fitting everything while keeping peak performance in mind. The plan is to eventually fly it on the Loki K1127 38-1200 load that I have from Aurora V1 that I never got to fly due to weather. The build will be fairly similar to the original however I will be using your typical 2x2 twill carbon fiber instead of the carbon/kevlar fabric I previously used. Everything will be hand laid except from the nosecone where I'll be using a thin-wall fiberglass 5:1 conical nosecone from Madcow Rocketry in order to allow the tracker to not have blocked RF signals. I'm still in school until the 15th so the build will start off slow until I'm back home and have all break to get to work on it. Below are some pictures of Aurora V1 along with the OpenRocket file for V2.
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Nice project, and welcome back! Many of us have been away for many years, only to rediscover the fun later in life! Glad you got back sooner rather than later!
 
I got my Proton in the mail today so I went ahead and assembled it. I will be using the Proton for the charge at apogee and for the cable cutter at a tbd altitude.
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I also received a bunch of other goodies for the build including the peel ply and carbon that aren’t in the picture. The nose cone is a 5:1 conical thin wall fiberglass from Madcow Rocketry. The professional JB weld will used be used for everything on the rocket, it’s what I used last time and it worked great. The 1ft section of extruded tubing will be my mandrel for the coupler, which unlike last time will also be rolled from carbon fiber. I already cut the Mylar and taped it onto the mandrel. I may give the first shot at rolling it this week but I have finals next week so we’ll see how much free time I have.
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Pretty cool, looks fast standing still. Any reason you aren't using a Quantum for DD since you don't need the extra channels? Also, what epoxy are you using for tube layup?
 
I happened to pick up a Proton during the Holiday sale and because I sold all my electronics when I left the hobby I’m slowly working on building up my fleet of electronics again. I’ll most likely end up using something different down the road once I have more, but right now the plan is to use the Proton because it’s all I have. I use US Composites laminating resin with their slow hardener, it has a pot life of about 30min and cures over night so it gives me enough time to finish with some time to spare.
 
Well I couldn’t help myself and I decided to attempt the first shot at rolling the coupler. I made a makeshift “rotisserie” to put the mandrel on.

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I’m starting out with 3 wraps of carbon. I cut the fabric using tape to keep the fabric from fraying, I only had scotch tape so I used it however masking tape is much better to use so I’ll be getting some before I roll the next tube. The cloth weighed out to be about 26 grams and I used about 32 grams of epoxy.

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This is the first time I’ve rolled a tube in about a year so I’m not expecting it to be perfect the first time but everything looks great so far and if I need to roll another then I will . We’ll see how it turns out tomorrow.
 
Besides a couple pinholes that I can easily fill in the coupler came out great! I will be post curing it for for about an hour at 150 degrees.

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The mandrel just so happens to fit perfectly in my toaster oven...

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Next is the best part of making composites, sanding...
 
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I've done some small diameter layups and ..you need to be careful. You found a couple of pin holes. What says that when your ejection charge(s) go off, that the unseen pin holes or the ones barely covered by epoxy ...are not the path of least resistance for your ejection gasses to go..

Tony
 
I've done some small diameter layups and ..you need to be careful. You found a couple of pin holes. What says that when your ejection charge(s) go off, that the unseen pin holes or the ones barely covered by epoxy ...are not the path of least resistance for your ejection gasses to go..

Tony

I’ll keep that in mind I may actually need to throw another wrap or two on in order to match the ID of my tubing but I won’t know for sure until I’m home and can measure the OD of my mandrel for the main body tube. As this is just the coupler it’s not something I’d worry about this problem with as much so as the main body tube itself. Thanks for the insight I may pressure test the tubes at some point to make sure they’re structurally sound and for my own amusement!
 
I went ahead and rolled another tube tonight. This time I used 5 wraps so the OD should be right where I need it. Everything went much smoother then last time so I’m hoping it turns out better then the first.

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Well this tube came out much better then the first, no pinholes and the OD seems spot on from what I can tell by comparing it to the shoulder of the nose cone.

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After a bit of sanding here it is wet after washing the dust off

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I also epoxied the shoulder of the nose cone in

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My fly away rail guide from Additive aerospace came in today and man have these come a long way since I left. I had the first version that was completely 3D printed, The new ones are really nice I’ll definitely be picking up more for future rockets.

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I have some more sanding to do on the coupler and then I will give it a skim layer of epoxy to make it nice and pretty.
 
Hey Connor, looks good. Can you explain what you mean by giving it a skim layer of epoxy or how you do it?
 
Hey Connor, looks good. Can you explain what you mean by giving it a skim layer of epoxy or how you do it?

Once the body tube is sanded down to where everything is smooth and the peel ply texture is removed I lay down a very thin layer of epoxy. I use Alex Laraways method of using a playing card to spread the epoxy evenly out over the tube. This fills in any very small “voids” there are and leaves a nice finish that will only need to be sanded with a high grit sandpaper before giving the entire rocket a clear coat.
 
Some more goodies came in the mail for this build today. I got the 38-1200 case from Scott and Loki Research along with the plugged forward closure which I will use for the shock cord anchor.

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I also got the TeleGPS with the TeleBT for tracking.

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I have my first 2 finals tomorrow and I’ll be home on Friday where I’ll be able to get back to the build.
 
I got home yesterday afternoon and got right to work at trying to setup my old work station the only problem was my parents got rid of my work bench so I had to make due with what I had.


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I ended up using jack stands for my car in order to support the mandrel while also allowing it to be rotated which worked out very well.

This time around I went with 4 wraps of carbon rather then 3 in order to match the OD of the nose cone better and for peace of mind for rigidity as the cloth I used for the original was a carbon/Kevlar hybrid.

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I cut out about 20” of carbon. A little tip for cutting the cloth, I’ve found the easiest way to get a straight line is by pulling 1 of the fibers out of the weave which will leave a perfect line for you to cut down.

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I decided to roll one large tube as the cloth is 50” wide so it required less cutting of the cloth rather then rolling 2 separate tubes. I’ll only need 44” of it so I have some wiggle room to cut from each side.

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Initially I mixed up about 100g. Of epoxy however halfway through I had to mix up some more. In the end I used about 225g. Of epoxy.


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This is the longest tube I have ever rolled but all went according to plan and it looks great all rolled up. I should be able to get it off the mandrel tonight and see how it turned out. Using some of the extra epoxy I gave the coupler the skim coat I had talked about a couple posts back. I’ll likely give it a light sand and then give it one final skim layer of epoxy.
 

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Well I’ll start off with the bad... I gave the tube 24hrs to cure, it felt hard to the touch and wasn’t tacky at all so I went ahead and pulled it off the mandrel. A nice trick if your tube won’t come off the mandrel easily is to shove some ice inside the mandrel (if you’re using a metal mandrel) and let it cool for a minute or two and usually the tube will slide right off as the metal will shrink slightly. Anyways I got the tube off and long story short it was still slightly malleable and deformed enough to the point where I didn’t feel comfortable using it even after putting it back on the mandrel to reshape it. I also found that the ID was a tad to small and when I measured my old mandrels OD to this one it was slightly smaller and my motor case could barely fit. To solve all these problems I re-rolled another tube today on my old mandrel so that I know the ID will fit the motor tube. The only downside is that I’ll have to roll the payload section separately.

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I also made the carbon plate for the fins today. I used 11 layers of carbon so the sheet should come out to be about 1/10 of an inch. I used some special carbon for the outer layers. I’ll give you a little sneak peak below. I think it’s going to look cool once the fins are airfoiled [emoji6]

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The fin plate came out looking perfect. I’m hoping the epoxy on the tube is completely cured by tonight and I’ll get that off the mandrel and see how it came out.

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This morning I took the tube off and removed the Mylar + pee ply. The tube came out fantastic. I’m going to roll the payload tube today and then it’s back to sanding.


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At this point the 7.5”X12” fin plate weights in 217g. And the body tube weighs in at 214g.
 
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I spent some time last night working on the sled.

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I used some old standoffs I had laying around. The battery was used to mock it up, I’ll be ordering a smaller 500mah 2s lipo to use.
 
I moved on to cutting out the fins today. I printed out the fin template from open rocket and used a white paint pen in order to trace them over onto the carbon plate.

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I used a Dremel with a cut off disk to make cutting out each fin quick and simple. Once they were all cut out I aligned them the best I could and clamped them all together.

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Using a sanding disk on my dremel I got them all down to the point where they could be hand sanded evenly while still clamped together.

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I airfoiled each fin by hand to get them to their final form.

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Together all three fins came out to weigh 47g.

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I’m excited to get these clear coated once the rocket is done as the carbon exposed by the airfoil transitioning to the purple reflections outer layer looks amazing.

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The nosecone sled for the TeleGPS I ordered from Lab Rat rocketry came in today and fit perfectly into the Madcow nosecone.


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I still need to sand the body tube a little bit more until I’ll be happy with it and then just like the coupler give it a thin coat of epoxy for its final layer.

More to come later....
 
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The thin epoxy coat is on the body tube. I used a heat gun to remove all the air bubbles that got stuck In the epoxy while brushing it on. Once it’s cured it’s onto sanding and cutting the tube to its correct length.

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I also applied a thin layer of epoxy on the airfoiled part of the fins so that it can be sanded down smooth and evenly while also protecting from de-lamination during flight.

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I assembled the tracker sled and installed it into the nosecone and everything fit perfectly.

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I found some slight problems with the tube when I went to work on it this morning. I don’t have pictures but some of the epoxy pooled at the bottom of the tube as it wasn’t being rotated. This won’t usually happen however I’m using the USC slow hardener which is why I believe it happened, as the epoxy had such a long period to build up before it began to gel and stay in place. I sanded the build up down with 150 grit sand paper and then went over the entire tube with it. I moved on to 400 grit and wet sanded the entire tube. Right now everything looks amazing. This is by far the best tube I’ve ever made. Tomorrow I’ll be picking up some 600 and 1200 grit sandpaper to finish the tube off.

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I finished the sanding the fins. They’re now ready to go on the tube once I finish it.

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I cut the tube down to length and test fit the motor with shock cord. I used a much thinner Mylar for rolling the tubes compared to the Mylar I used for the other build so the motor fits in very snug which is perfect as there’s no need to use tape to friction fit it. I did however slightly sand the inside of the tube using a dowel with sandpaper taped to it to make it slide in a little smoother.

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It’d be really nice to have a lathe right about now... the coupler needs to be sanded down quite a bit in order to fit the body tube. I jerry rigged the coupler to a hole saw that was just about the same diameter using duct tape and used my drill and some 80grit sandpaper to begin sanding it down. I got it pretty close before my drill battery died, once it’s charged I’ll get back to it.

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Heres an updated Open rocket file:
 

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I made a fin marking guide as I couldn’t get my printer to stop cutting off the top of the one from openrocket. I measured 1” from the rear and marked it off with some electrical tape, this makes it easy to draw a straight line around the tube.

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Using a piece of angle iron I extended all of the lines onto the tube and removed the tape.

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I planned on tacking the fins on tonight however it’ll have to wait as I can’t find my old BH38 fin alignment guides so I ordered another set from Wildman.
 
Nice thread so far. Makes me want a BH38 for L2 next year.
 
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