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mtnmanak

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Moving on to the forward fins. Using the medium size guillotine fin jig for the forward fins. Makes short work of it. Setting the fins in with 5-min quick cure epoxy since the main structural bond will come from the epoxy I inject later on. Procedure is simple as lining up the body tube in the jig (the lines I drew down the BT earlier make this very easy), getting the guides aligned properly, buttering the root edge of the fin and seating it in the slot. Just make sure the fin is securely against the MMT. Going to allow each fin to cure for about 20 min before rotating the body, so will be back with an update later after I finish the three forward fins.

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tOD

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Moving on to the forward fins. Using the medium size guillotine fin jig for the forward fins. Makes short work of it. Setting the fins in with 5-min quick cure epoxy since the main structural bond will come from the epoxy I inject later on. Procedure is simple as lining up the body tube in the jig (the lines I drew down the BT earlier make this very easy), getting the guides aligned properly, buttering the root edge of the fin and seating it in the slot. Just make sure the fin is securely against the MMT. Going to allow each fin to cure for about 20 min before rotating the body, so will be back with an update later after I finish the three forward fins.

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Nice jig!
 

mtnmanak

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Nice jig!
Ted & Charlie Macklin make these over at Macklin Missile Works:


They will sell you the parts or you can buy the plans for them and make them yourself at whatever size you want. You can buy them from Apogee too, but they charge a premium.

Best bet is to figure out what you want and talk to Ted Macklin. They are awesome at custom work and are really nice folks to work with.
 

mtnmanak

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Okay, Turkey Day operations are commencing soon, so going to concentrate on getting the other centering rings in and the rear fins and then will have to pick this up later in the weekend.

For the "middle forward" CR, use a long stick to slather a good bit of quick set epoxy around the body tube and MMT at the rear edge of the forward fins. Main intent is to seal the CR so later when we inject the laminating epoxy, it doesn't leak every where. Other thing to watch out for is that there is very little space between the MMT and the BT - be careful not to get epoxy on the walls while you slide the stick down because it will be almost impossible to wipe off and then you won't be able to slide the other CR in. Also, keep all epoxy away from the fin lines drawn on the MMT. Guess I should have noted above - when you install the MMT, make sure the fin lines you drew/kept clean line up with the fins slots.

Once you have the epoxy in place for the CR, I use two dowels to push the CR down the tube and get it in place resting on the back of the fins. I am horrible at taking photos that focus in the right spot, so the photos I took of this don't show down the tube very well.

I moved straight on to the next CR. Mix up another larger batch of quick set epoxy. Use the stick again to fillet the back of the "middle forward" CR and to set a line of epoxy for the "middle back" CR right at the forward edge of the rear fins slots. Again, I use the dowels to push that CR in place. This one is tricky because you have to be careful when you get close. If you push it too far, the really isn't a way to pull it back. So just nudge it until it lines up with the forward end of the fin slots and (for my fit) about half the CR is showing.

A lot of text there, but I think it took me longer to type this than it did to actually do it!

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mtnmanak

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Before I get the rear fins on, I installed the rear rail buttons. As I have noted in other threads, I install both 1010 and 1515 rail buttons on any rocket that can handle it. I do this not because this rocket needs a 1515 button, but because it greatly adds to my flexibility at the field. At METRA, for example, there is often a line for the 1010 pads, but the 3 or so 1515 pads are almost always empty. Not only can I skip the line if I have 1515 buttons on the bird, but the 1515 rails are usually longer, which is nice, and I feel like it is a bit of "community service" to my fellow rocketeers to not take up another 1010 pad slot that someone else could use. Be a good neighbor - install both!

I drilled the holes for the weld nuts and tacked them in place with CA. I screwed the rail button on to ensure the weld nut was tight. While the screw was in, I placed tape over the weld nut on the back to protect the threads from epoxy, then coated the whole weld nut with quick set epoxy. Allows you to still remove the rail button and seals it against the injection epoxy later.

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mtnmanak

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Okay, rear fins and rear CR, then probably done for the weekend.

Now that the middle CRs are in and the rail buttons are on, pulled out the larger guillotine jig and am aligning the rear fins to the front fins to ensure they are perfectly in line. CJ just used a popsicle stick and a couple clamps in his build, but if you have the jig, may as well use it. Once again, securing the root edge of each fin with quick set epoxy, so should take about an hour to get them all in.

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mtnmanak

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Last update for the weekend, rear fins are in place and look great. Glued the rear CR in place and put a healthy layer of epoxy over it, being careful not to get any on the area where the retainer will be glued. Also, used a toothpick to put a thin line of epoxy in the fillets of the fins to form a nice seal when I inject the laminating epoxy.

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Idunno

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Last update for the weekend, rear fins are in place and look great. Glued the rear CR in place and put a healthy layer of epoxy over it, being careful not to get any on the area where the retainer will be glued. Also, used a toothpick to put a thin line of epoxy in the fillets of the fins to form a nice seal when I inject the laminating epoxy.

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What kind of epoxy did you use for the fin seal? Does the laminating exopy adhere as well to epoxy as it does to FG? I'm just wondering if that somehow might weaken the joint.
 

mtnmanak

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What kind of epoxy did you use for the fin seal? Does the laminating exopy adhere as well to epoxy as it does to FG? I'm just wondering if that somehow might weaken the joint.
Just used quick cure epoxy to seal the seams. Not too concerned about the laminating epoxy adhering to it - the quick cure is in the external fillet space and the laminating epoxy is all internal. For the external fillets, I am going to use RocketPoxy and will sand the fillet again before applying, but also not too concerned as the large external fillet will have a lot of fin and body tube to adhere to.
 

mtnmanak

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Got all the seams taped up this morning. Will be using Aeropxy 2032 with some milled FG mixed in. Using about 1/2 tsp of FG. Mixed up the epoxy by volume then put a couple drops of black dye (the kind you get with RocketPoxy) in to make it easier to see the flow of the epoxy once I inject it. Leveled off the fins and injected the epoxy. Took about 5ml per hole. Little more for the front hole, little less for the back holes. Going to let this sit level in the "hot room" till it gels (about 4-5 hours) then repeat. Hope to get all the injections done today so everything can cure overnight.

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mtnmanak

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While I am waiting for the glue to cure inside the fin can, went back to the AV bay. Got the terminal blocks installed. I am using the smaller, through the bulkhead kind for this narrow diameter tube. Never been quite sure how you are "supposed" to install these, but this is the way I have always done it and it has worked well so far.

I use a wire wrap tool to wrap some 20 AWG wire on the terminals. Then, solder it on. Then heat shrink tube the solder joints. I drill holes in the bulkhead to fit the solder joints, pull the wires through, test for continuity before gluing the terminal block down, then use some quick cure epoxy to anchor the terminal block. Whatever epoxy I have left, I put on the other side to further seal the holes. Did same thing for the other terminal block.

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mtnmanak

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All electronics and connections complete. Did one final test with all components and everything checks out. AV Bay is complete.

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mtnmanak

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The internal fillet epoxy seems to have settled nicely. Moving on to the external fillets. There were a few spots where the epoxy I used to seal the edges got a little wider spread than I wanted, so I sanded all the fillet areas down again - can't really sand too much to prep for epoxy anyway, I guess. Using RocketPoxy with the black dye. Used the 1/2" PVC pipe that I will use to smooth the fillets to mark out the areas to tape. RocketPoxy is not viscous enough when you first mix it to stay nicely the way you shape it (it will flow out too much), so I mix the RocketPoxy first, then mark out and tape the section I am going to fillet. By the time I have my pencil lines drawn and gotten the tape down, the RocketPoxy is just starting to stiffen up. Timing works out so that by the time I gloop it on and smooth out the fillets, it is gelled enough to pull off the tape and clean up any errant drips. Then I set it aside in the hot room. Will give each section a couple hours and then do the next one. Should take me the rest of the day to get them completed.

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mtnmanak

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Almost done with the 2.6" Darkstar. Next item was to get the bulkhead on the nosecone. The way the bulkhead is as it comes in the kit, it sits as a cap at the end of the nosecone. I don't plan to use the nosecone for any electronics, so not concerned about gluing the bulkhead in place, but it is not very secure if it is attached as an end cap. I sanded the outer diameter down a bit so it would fit snugly in the shoulder. I also like this arrangement because it makes it easier later to get the broken shear pins out.

Once I fitted the bulkhead in, I made a line with a metallic Sharpie. In Wayne and CJ's threads, they talked about using a silver sharpie. Not sure if the broader "metallic" line was created later (those threads are 4+ years old), but now you can get the metallic line in blue, gold, silver, red, etc. These are great for writing on black surfaces.

Put a generous line of quick cure epoxy around the line, inserted the bulkhead, let it cure for about 10 min, then sealed the whole thing up with Proline 4500. Should be able to handle ejection charges.

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mtnmanak

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Few last odds and ends to the 2.6".

Drilled the vent holes in the sustainer tube and the payload tube. Holes are 1/8" drilled in the middle of the tubes. I am not putting another vent hole in the AV Bay. For a 2.6" diameter bird, I think the 1/4" switch hole in the AV Bay will suffice.

Wayne noted this on his thread, but it is good to repeat the tip - if you put a piece of PVC pipe in the tube when you drill a hole, it very much helps to prevent tear out on the inside. Also, as Wayne noted, it is a good idea to back the inside with tape. In this case, the tube is too small for me to reach down and get tape inside, so I just relied on the PVC pipe. Small amount of tear out, but good for a vent hole.

Also drilled the holes for the shear pins and tapped them for 2-56 pins. Put the holes a 1/2" up on the shoulder of the NC, which leaves them below the bulkhead for ease of removal. Used 2 shear pins for this build.

When I paint, I will leave the shear pins in and the screws connecting the AV Bay to the payload tube (will tape over it) so after wards it is easy to keep everything lined up to make some subtle witness lines.

She is done. Next up, painting, ground testing and the 3" version!

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mtnmanak

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The 2.6 now has 3 coats of primer (wet sanded with 400 grit) and 4 coats of Dupli-Color Black Gloss (wet sanded with 800 grit between the 2nd and 3rd coats). The lacquer dries pretty quickly, but still going to give it a couple days before I put the Stickershock decals on. Will clear coat later in the week and, if the weather holds out, will hopefully launch it next weekend at MDRA.

Also, ground tested it before I put the paint on. Charge calculator recommended 0.5g of FFFFg for the main, but that wasn't enough. Took 0.8g to get the nosecone to eject and a full 1.0g to get the "authority" I was looking for. Will fly it next week with 1.0g in the payload bay and 0.8g in the fin can.

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hball55

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Can't believe no one has referenced the "Bible" on building Darkstars:
https://www.rocketryforum.com/threads/how-to-build-a-stock-3in-darkstar-cj-step-by-step.55019/

Literally hundreds of rockets have been built using CJ's guide. My DS Jr., 3" DS, DS Extreme and Ultimate DS were all built using that thread as a reference, and those four rockets have well over a hundred flights. If you do your "Y" harness correctly according to that thread, you will NEVER have to replace it.

I did my Level 3 with a Darkstar Extreme and documented it for my TAPS with this thread:
https://www.rocketryforum.com/threads/waycos-dark-star-extreme.66950/

Here is my build thread for the Ultimate:
https://www.rocketryforum.com/threads/waycos-ultimate-darkstar-build.126244/
Only problem I have had on the six flights I have made with this rocket was the rail buttons came off when I flew the O3400 Imax motor last year at Airfest.
When you say Bible reference, do you mean “Let there be light,” from the movie? For me, Darkstar is my favorite Grateful Dead song.
 

mtnmanak

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Still waiting for the decals to arrive - they are supposed to get here today, so hopefully will be able to get those on and clear coat tonight.

I had almost forgotten to install the retainer! Would have been a surprise when I got to the field this weekend :). Re-scuffed the end of the MMT and dug out my well used tubes of JB Weld. Put a healthy ring around the tube and twisted the retainer on. Used a 38mm case to ensure the retainer remains centered (the Aeropack retainers are slightly loose on the Wildman thin walled tubes) and set aside to cure for the rest of the day.

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Wayco

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There is usually an aluminum "shim" ring included with the Aero pack retainer, which fits between the MMT and the retainer, although your method works too. Give the JB weld at least a day to cure before you pull the casing.
Thank you for posting your build thread, I'm always interested in different methods that people use to do things.


When you say Bible reference, do you mean “Let there be light,” from the movie? For me, Darkstar is my favorite Grateful Dead song.
I hope you are just being funny, but I'm not familiar with the movie you are mentioning, so I can't tell if it's humor. My answer would be no in any case. I know and like the song though.
 

mtnmanak

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There is usually an aluminum "shim" ring included with the Aero pack retainer, which fits between the MMT and the retainer, although your method works too. Give the JB weld at least a day to cure before you pull the casing.
Thank you for posting your build thread, I'm always interested in different methods that people use to do things.



I hope you are just being funny, but I'm not familiar with the movie you are mentioning, so I can't tell if it's humor. My answer would be no in any case. I know and like the song though.
Thanks - I did notice a number of references to the shim, both from Aeropack and a reference somewhere that Wildman, at one point, shipped one with their kits. I did not get any shims with the retainers or kits. It looks like Aeropack made a different version of the 38mm retainer (the RA38L2 - https://aeropack.net/referencelist.asp) that is designed specifically for the Wildman thin wall FG MMT's and that is the version I used here, but I can tell you it is still pretty loose. Not nearly as loose as the other 38mm variations, but still loose enough that I want the 38mm case in the tube until it cures.

Looking at the Aeropack 54mm and 75mm retainers, though, there is no updated "L2" version. It looks like you you are expected to use the "P" versions at those sizes. None of the retainers or kits I received in the last couple months include a shim. I test fitted the "P" versions on both the Wildman 54mm and 75mm MMTs and they are very loose. I do also have the flanged 54mm and 75mm retainers, but I am unsure how to use those if I want to use the Aeropack tailcone. The MMT needs to be extended quite a bit from the end of the fin can to accommodate the tailcone adapter, so there is no way to attach the flanged retainer to the rear CR. I will have to think about it.
 

mtnmanak

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Thank you for posting your build thread, I'm always interested in different methods that people use to do things.
Thanks - I do think a benefit of people posting build threads for rockets that already have a lot of coverage on TRF is that materials do change over time. Your build threads are amazing and put mine to shame, for sure, but there have been a few changes to the materials you get in the DS kits, so it may be helpful for people to see what they would get if they buy the kit now. The changes are sometimes small, but can be significant. For example, I noticed in previous DS threads, a fair bit of posts concerned the number of CRs that came in the kit. I can tell you that I have purchased 5 x DS kits from Wildman in the past year and they all came with 4 x CRs (which is great!) and all the rockets above 3" came with aluminum bulkheads. Great changes!
 

Wayco

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The treaded part of the Aero Pack tailcone retainer is attached to the MMT, which does have to be extended like you said. Flanged retainers can only be attached to a flat centering ring, so you can't use them for a tailcone retainer.
I really like the look of the tailcone retainer, and have several of them in my fleet. The downside of using them is that they have to be modified to fit snap ring casings.

Wildman definitely has his finger on the pulse, and constantly modifies his kits to make them irresistible.
The 2.6 kit you are just finishing is one of the few darkstars I don't have in my fleet, but I'm sure that will change in the near future. The beauty of working with Wildman is that he has no problem substituting parts, like a 54mm MMT and centering rings to fit. :D
 

mtnmanak

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The treaded part of the Aero Pack tailcone retainer is attached to the MMT, which does have to be extended like you said. Flanged retainers can only be attached to a flat centering ring, so you can't use them for a tailcone retainer.
I really like the look of the tailcone retainer, and have several of them in my fleet. The downside of using them is that they have to be modified to fit snap ring casings.

Wildman definitely has his finger on the pulse, and constantly modifies his kits to make them irresistible.
The 2.6 kit you are just finishing is one of the few darkstars I don't have in my fleet, but I'm sure that will change in the near future. The beauty of working with Wildman is that he has no problem substituting parts, like a 54mm MMT and centering rings to fit. :D
Absolutely - love these kits!

For the Aeropack tailcone retainers and snap ring casings, I have a bunch of relatively new Loki casings that, as far as I understand it, have been modified to fit in the Aeropack retainers without using the spacer. As I am starting to build out the 3", I will definitely test it and revert back on that build thread. Would love it if my Aerotech and Loki motor casings will fit the retainers with no further modification. I only started using Loki this year, so I don't have any of the older casings to compare.
 

Banzai88

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There is usually an aluminum "shim" ring included with the Aero pack retainer, which fits between the MMT and the retainer, although your method works too. Give the JB weld at least a day to cure before you pull the casing.
Thank you for posting your build thread, I'm always interested in different methods that people use to do things.
In the last 5 years since BAR I have used every aeropack catalog number from 29-54mm in size, I have yet to get an additional spacer ring with any of them.

Is this still a 'thing' or is it perhaps vendor specific?
 

mtnmanak

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Since I have other DS builds lined up, these retainer discussions are really important to me and I appreciate the feedback. Pretty much the entire build process is setup around the retainer. Once you figure out your retainer plan/design, it ends up driving everything else you are going to do with the fin can. It is really hard to change things after epoxy is cured!
 

crossfire

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There is usually an aluminum "shim" ring included with the Aero pack retainer, which fits between the MMT and the retainer, although your method works too. Give the JB weld at least a day to cure before you pull the casing.
Thank you for posting your build thread, I'm always interested in different methods that people use to do things.




I hope you are just being funny, but I'm not familiar with the movie you are mentioning, so I can't tell if it's humor. My answer would be no in any case. I know and like the song though.
The sim ring is from WM its gives a tighter fit with WM light weight FG tubes.
 

Banzai88

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The sim ring is from WM its gives a tighter fit with WM light weight FG tubes.
I guess you have to ask specifically for them, I don't see them listed on his web page anywhere.
 
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