Darkstar Series Build

[mtnmanak]

Alrighty!! Got some help this morning and wrapped the long booster tube! Didn't get any pictures of the process, our hands were kind of full, but took one of the fin slots after trimming. The whole thing came out incredibly - Mark really made an awesome wrap for this "Neutron Star"!

 

[TheTank]

Looks great. Just finished the 4” myself. Cant wait to fly it at Metra or MDRA. Just needs to warm up so I can paint. I also saw the discussion on retainers a few pages back. I found my standard aeropack 54mm was really loose. I see wildman has a RA54P-TW listed on their site. Pretty sure that is the one I need. I didnt want to fill the gap with JB weld and hope it held. Wish I had thought about the tail cone after seeing yours!

 

[mtnmanak]

Looks great. Just finished the 4” myself. Cant wait to fly it at Metra or MDRA. Just needs to warm up so I can paint. I also saw the discussion on retainers a few pages back. I found my standard aeropack 54mm was really loose. I see wildman has a RA54P-TW listed on their site. Pretty sure that is the one I need. I didnt want to fill the gap with JB weld and hope it held. Wish I had thought about the tail cone after seeing yours!

View attachment 448500

Nice! Looks great! I definitely plan the maiden flight for the 4" and 3" to be at MDRA in Feb, but looking forward to getting back to METRA in a couple months.

 

[mtnmanak]

Started on the forward fins today, got them all glued in at the root.

First, trimmed 2mm of the wrap away from the fin slot to promote better adhesion. I plan to use Proline later for external fillets to get that nice gloss black that should go well with the fins and wrap.

 

[mtnmanak]

With the forward fins all epoxied in at the root, I epoxied in the CR that goes right behind the fins. I used a generous amount of mid-cure epoxy to ensure a good seal for when I inject the internal fillets. Also, should note that this time when I epoxied the fins in, I paid particular attention to getting a generous amount of epoxy on the forward edge of the fin tab and the beveled edge. Really trying to get a great seal in the fin compartment this time to avoid leaks!

 

[mtnmanak]

Between shoveling out copious amounts of snow today, I will be injecting the internal fillets on the forward fins.

First step, make sure everything is sealed. I got leaks on the past two builds, so spending extra time for this build - I don't want to leak epoxy on that nice wrap.

I beefed up the fillets on the rearward CR with some quick cure epoxy, just to make sure there aren't any gaps I missed. Then I went around each fin and sealed the edge with some quick cure epoxy, making sure this time to really concentrate on the beveled ends of the fin tabs to ensure I get some down in the gap. I think this is where I got the leaks last time.

Finally, taped the holes shut on the fin sections I won't be filling first

 

[mtnmanak]

Started injecting the fillets. Using West Systems 105 Resin with the 205 "fast" hardener. Switching from Aeropoxy 2032 that I used on the earlier builds. I love the Aeropoxy epoxy, but I have to admit that it takes forever to cure, even if you can keep the heat up. West 205 gets to leather stage in just a few hours, even at room temp, so should be able to get all the fillets injected in one day instead of two days. Also, switching to West 406 Colloidal Silica from milled FG. I am skeptical that milled FG does much to increase the strength of the epoxy whereas there is ample evidence that the colloidal silica actually increases the structural strength, so mixing in about 1/2 a teaspoon or so. Also, using some black dye (the stuff that comes with RocketPoxy). Reason for the dye is to be able to better see where the epoxy goes (i.e. - if I get a leak) and so that any epoxy that comes up through the hole matches the black fins/future external fillets.

I leveled out the rocket laterally and longitudinally before injecting the epoxy.

I used a 20ml syringe and injected 10 ml into each side of the fin compartment. That didn't fill it up, but it was definitely enough to move the rocket around and coat the whole fin tab with a decent layer of epoxy. Don't see a need to put excess epoxy in when all it would do is add unnecessary weight. Will fill the holes separately.

 

[mtnmanak]

Alright, so far, so good - no leaks! proceeding with the other fin sections

 

[mtnmanak]

Filling up the injection holes this morning. Using Aeropoxy 6209 mixed with a copius amount of West 404 High Density filler. Mixed it to beyond peanut butter consistency so it would stick in the hole. Mixed in some black dye to make sure I don't give myself more problems later with the color.





realized it looks like there is a hole in them middle of the patch, there isn't - it is just a weird reflection or something in the photo

 

[mtnmanak]

taking a short break from epoxying parts today to paint the nosecone. I sprayed it with one coat of primer and sanded it down to find the low spots. These nosecones from WM can be a little "fuzzy" with FG threads and also have some grooves in the weave. So, sanded off the fuzzies and filled in the grooves with some bondo. Then sprayed it again with 4 coats of Duplicolor engine primer and wet sanded down to 800 grit.

 

[mtnmanak]

With 3 coats of Duplicolor Engine Black Gloss:

 

[mtnmanak]

And, finally, with 4 coats of Duplicolor Engine Clear Gloss:

 

[blackjack2564]

your doing a fine job there, young man!

 

[mtnmanak]

your doing a fine job there, young man!

Thanks Jim, that's high praise!

 

[mtnmanak]

Next step - getting those rear fins in. This rocket is too long to fit in the guillotine jig for the rear fins, so just using some angle aluminum to ensure the rear fins are lined up with the front fins. Just using regular 5 min epoxy to tack the fin root to the MMT - going to fill the internal fillets after that. Should take about 10 min per fin, so will get them all in tonight and put it up to cure until tomorrow.

Only the top fin is epoxied in this photo - the other two fins are taped in to allow the Badass rocket jig to help keep things straight.

 

[mtnmanak]

Rear fins are in and bonded to the MMT

 

[mtnmanak]

Working on the internal fillets for the rear fins today. Using Aeropoxy 6209 with enough colloidal silica to make it into a very thick paste. This is probably one of the most fun activities in HPR - glooping epoxy into a fin can for internal fillets

The black dye in this case is merely to make it easier for me to see where I have put the epoxy. If I don't dye it, it is really difficult for me to see the translucent epoxy way down in the tube and I can't be sure I coated all the necessary surfaces. The black dye makes it foolproof (and, I have been called a fool many times. Usually by the household commander when she see another big box of rocket parts come in...).

First, taped off the ends to avoid getting epoxy where the rear CR and retainer will go.

Generously coated the fin section, leaving about 1/2" at the end of the fin un-epoxied to avoid interfering with the rear CR. Will get that short section when I install the rear CR later.

 

[Zman1961]

Great thread, thanks for sharing all of this information! Will start my build soon.

 

[mtnmanak]

Great thread, thanks for sharing all of this information! Will start my build soon.

Good luck, these are great rockets and really fun to build

 

[mtnmanak]

Alright, alright, alright. With the internal fillets done and cured, moving on to the external fillets. Using Proline 4500 for this. Usually I use RocketPoxy for external fillets, but I was looking for that inky black Proline delivers.

I cut the wrap back 2mm earlier in the thread and want a little bit of overlap with the fillet, so measuring out 3mm from the fin to tape off the fillet area. Once the mask was in place, applied the Proline and smoothed with a gloved finger. Then I removed the tape in about 10 minutes, hoping the edge of the Proline will settle just a bit. I don't want to mess with it too much, concerned about messing up that nice wrap. Worse case is that there is a bit of a square edge on the fillet that stands proud of the wrap/fin. Nothing I can't live with and not worth screwing up the wrap or paint on the fin. Came out good enough for me. The other two fillets are my project for today.

 

[mtnmanak]

Got bored tonight waiting for epoxy to cure, so took advantage of the time to sew up the shock cords.

Using 5/8 tubular nylon for the main and the 3/4" nylon web for the drogue. Each is 20 feet in length.

All loops are sewn with 150 lbs Kevlar thread and then covered with high strength heat shrink tubing.

1500 # swivel for the main.

 

[mtnmanak]

With the external fillets done, next few steps were all done at once:

- Installed the weld nuts for the rear rail buttons. Tacked them in with CA and held them tight by screwing in the rail button while the CA dried.
- Placed a tape-round on the back of the weld nut to protect the threads from the epoxy
- Had the Proline out from the external fillets, so mixed up a largish batch and put a generous amount around the MMT, body tube and rear edge of the fins for the rear CR. Also, coated the back of the weld nuts while I was spreading epoxy around
- Installed the rear CR tight against the rear of the fins
- Used the rest of the Proline to spread an even coat on the rear CR
- Finally, mixed up a batch of JB Weld and epoxied the retainer in place. Placed an Aerotech 54mm 2800 case in the MMT tube to keep the retainer centered and weighted down while the JBW is curing.
- Set the whole assembly aside to cure overnight.

 

[mtnmanak]

All epoxy is nicely cured - test fit the tailcone retainer over the motor case, no issues. Also epoxied in the upper rail button weld nuts.

Just need to finish up the nosecone ebay, and it will be ready for ground testing.

 

[mtnmanak]

The 4" NeutronStar is complete!

 

[mtnmanak]

Flew both the 3" Brightstar and the 4" Neutron Star this weekend at MDRA.

Here is the video from the Brightstar. Only flew it once on an I599. Flew perfectly and all events exactly as expected, but something happened to the magnetic switch for the Raven and could not get it working again that day, so didn't try anymore flights. Too bad because the weather on Sunday was picture perfect and it would have been cool to really blast this rocket up on an L motor!

 

[mtnmanak]

Here is the video from the Neutron Star flights over the weekend at MDRA:

Launch 1 (20 FEB 2021): Loki J-474
Launch 2 (20 FEB 2021): Aerotech K-400
Launch 3 (21 FEB 2021): Aerotech L-1090

Weather was a big factor this weekend. On Saturday, the temp was in the upper 20's, but the 15+MPH wind pushed the wind chill down into the teens and also pushed our rockets a long ways. Sunday, however, was absolutely perfect. Got into the low 40's and, by afternoon, zero wind.

On the first launch, the deployment bag wrapped around the main chute causing a partial failure. It is hard to see in the video, but the chute opens fully for a split second, then it collapses as the cord wraps around the shroud lines. Luckily, there was no damage to the rocket.

On the second flight on the K-400, the wind was extremely strong and the rocket landed about a mile away. Long walk through a very frozen corn field, but everything worked properly on that flight. I was using a Marco Polo tracker in my rockets this weekend and it really came in handy for this flight!

On the last launch on the L-1090, it was picture perfect and landed right back in the parking lot. In the video, you will hear 7,000 feet mentioned a couple times. That was not the correct data. I had run the sim in both TC and Rocksim. TC indicated 7200 feet and Rocksim indicated 9400 feet. I was going with the 9400 feet, but inadvertently wrote the TC data on the flight card. Actual flight data recovered from the RRC3s indicated almost exactly 9400 feet and 708 MPH. The rocket landed in the parking lot with the booster section on one side of a car and the payload section on the other side of the car with the shock cord draped perfectly over the roof of the car. The nosecone does hit a minivan roof (can see it in the video), but it hit flatly and didn't leave a mark. Luckily, no cars were injured in the making of this video!

 

[g.pitts]

Here is the video from the Neutron Star flights over the weekend at MDRA:

Launch 1 (20 FEB 2021): Loki J-474
Launch 2 (20 FEB 2021): Aerotech K-400
Launch 3 (21 FEB 2021): Aerotech L-1090

Weather was a big factor this weekend. On Saturday, the temp was in the upper 20's, but the 15+MPH wind pushed the wind chill down into the teens and also pushed our rockets a long ways. Sunday, however, was absolutely perfect. Got into the low 40's and, by afternoon, zero wind.

On the first launch, the deployment bag wrapped around the main chute causing a partial failure. It is hard to see in the video, but the chute opens fully for a split second, then it collapses as the cord wraps around the shroud lines. Luckily, there was no damage to the rocket.

On the second flight on the K-400, the wind was extremely strong and the rocket landed about a mile away. Long walk through a very frozen corn field, but everything worked properly on that flight. I was using a Marco Polo tracker in my rockets this weekend and it really came in handy for this flight!

On the last launch on the L-1090, it was picture perfect and landed right back in the parking lot. In the video, you will hear 7,000 feet mentioned a couple times. That was not the correct data. I had run the sim in both TC and Rocksim. TC indicated 7200 feet and Rocksim indicated 9400 feet. I was going with the 9400 feet, but inadvertently wrote the TC data on the flight card. Actual flight data recovered from the RRC3s indicated almost exactly 9400 feet and 708 MPH. The rocket landed in the parking lot with the booster section on one side of a car and the payload section on the other side of the car with the shock cord draped perfectly over the roof of the car. The nosecone does hit a minivan roof (can see it in the video), but it hit flatly and didn't leave a mark. Luckily, no cars were injured in the making of this video!

View attachment 452447

View attachment 452448

Very nice build thread, @mtnmanak - thanks for sharing it and the flight videos! Looked REALLY cold to me.

 

[mtnmanak]

6” Darkstar Ultimate build starts here.

It has been a while since I worked on the Darkstar series. Last year, I purchased the entire line of Darkstar kits from Wildman at the Black Friday sale and had the intent of building them all out in this thread. I got derailed earlier in 2021, mostly by my Level 3 project, which is now complete.

So, moving on with the DS rockets, next up is the 6" Ultimate. I am looking forward to adding this rocket to my fleet – it is a nice mid-weight HPR that will fly nicely on a wide variety of big motors.

Much of the build will be similar to my earlier Darkstar builds, but there have been some improvements to the process over the past 8 months. First and foremost, I acquired a Shapeoko 3 CNC machine since the last Darkstar build and now fabricate a number of my own parts, which allows me a fair bit of flexibility. I do not have a 3D printer yet, but I imagine when I finally do get one, it will further improve the scratch portion capability of these builds.

I will try to highlight the changes throughout the build.

As usual, first step is to wash and sand everything with 220. Once you get to this size of a rocket, I do highly recommend a good orbital sander and high quality sanding discs. It makes life so much easier.

I should note that the original booster tube I received was quite misshapen around the fin slots. Tim at Wildman replaced the tube and the second one was excellent.

Here is a photo of the parts you get plus some of the items I have already added, such as the Aeropack retainer, a Onebadhawk bridle and a thrust plate I CNCed.

 

[mtnmanak]

Preliminary Rocksim file, will update at the end with actuals. This file reflects the parts sent in the kit and a couple parachute/shock cord placeholders to do some notional motor checks.

 

[mtnmanak]

Started this build off by CNCing a thrust plate out of 0.19" aluminum to hold the Aeropack 98mm retainer. The flange holes were CNCed in the precise location and tapped for the 8-32 cap head screws.