Darkstar Series Build

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gerbs4me

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I have tapped holes into maybe... 20 or 30 FG rockets? Maybe more? So far, none of the holes have failed.

To be fair, we are mostly taking about nylon shear pins here. Not a lot of stress on the threads.

Generally, if I am going to need to put a metal screw into a rocket, I use a PEM nut.
thanks for replying

good point about them being shear pins
 

mtnmanak

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Really moving this along now, but had to pause a bit tonight. I was rushing this build and (besides putting the rear fins on backwards!) ran into a number of issues when trying to get the Ebay wired and ready.

First part went well. I put aluminum brackets on either side of the switch bracket to hold it in place and tapped in holes for the standoffs for the Proton and the RRC2. Once that was done, I marked out and drilled the holes in switch band for the switches and vents. All good.

Things went sideways when I started working on the Proton. I had previously assembled and tested the Proton, so that wasn't an issue, but I built it a while ago and had soldered a bridge between the DP+ and B+ pads because I figured I would probably use it in single battery mode. No big deal, get out the solder wick and remove the bridge. Then I soldered JST connectors to the proper pads for both the deployment and logic batteries. Then I installed the board back on the sled and went to attach the leads from the terminal blocks. Here I ran into the next issue - when I assembled the board, I chose to use the green terminal blocks that come with the kit. Frankly, I must have really messed up that soldering job. Of the 12 ports, 9 of the screws would not screw down. I must have melted them or something, who knows. So I took the board off and started trying to de-solder each connection. In doing so, I managed to break one of the terminal blocks off. It didn't damage anything, but it was a lot harder to de-solder. After about an hour of wrestling with the damned things, I finally got one off and all the solder off the board. I cleaned up the pads and soldered 4 wires to two of the channels. I reinstalled the board on the sled and then realized I had put male JST connectors on the battery pads and they needed to be female. And to add insult to injury, I had installed the board with the "UP" arrow pointing toward the aft end of the Ebay and the battery wires would be the wrong length if I turned the board around.

At this point, I was tired and frustrated and realized I needed to walk away for a while. I went and had some dinner, watched some TV, etc, then came back with fresh eyes. I de-soldered the JST connectors, soldered the proper ones on and did a thorough check to make sure I didn't miss anything. I installed the board back on the sled in the proper orientation and proceeded to wire everything up. I finished up wiring the RRC2 and the batteries and the final pictures are below.

Some highlights:
  • Eggtimer Proton with a LiPo for the logic and a 9V lithium for the deployment
  • RRC2L backup with a 9V lithium
  • Nose end bulkhead fixed in place, all wires from those terminal blocks directly wired to the boards
  • Aft end bulkhead removeable, leads have 3M quick connects in the middle
  • All batteries on opposite side of sled from electronics to help protect them if one gets loose
  • LiPo zip tied to sled
  • 9V batteries in modified battery boxes. I remove the switches and hard wire leads to the terminal connectors. Battery box covers are held in place with a screw during flight so the 9V batteries are completely enclosed
  • Pictures show 400 mAh LiPo for testing, actual flights will use an 800 mAh LiPo
Once completed, I did continuity tests and a test ematch fire on all channels.

I hope to get the nosecone bay done later tonight and ground test this tomorrow.

PXL_20211012_225459592.jpg

PXL_20211013_144817862.jpg

PXL_20211013_145202798.jpg

PXL_20210730_215134755.jpg

PXL_20210730_215403983.jpg

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PXL_20210730_220248486.jpg

PXL_20211017_081036862.jpg

PXL_20211017_081149174.jpg
 

mtnmanak

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For the nosecone bay, I mounted a Featherweight GPS to a 38mm ebay sled from Additive Aerospace. Works okay. Main intent is to be able to more easily move the tracker from rocket to rocket. The plastic mount is held to the sled with two 4-40 bolts. I plan to add these mount holes to the sleds on my other rockets that can handle it. I also put a mount in for the Marco Polo tracker, which I will use for lower altitude flights.

For the sled, it is just a piece of .08" thick FR4 sheet with 1/2" tubes JB welded to the bottom and then laminated with a piece of FG cloth.

The sled slides onto the bay rails. The rails are 5/16" nylon all-thread. I am honestly not sure how these are going to hold up. First time I am trying nylon. The nuts are made from fiberglass. The intent was to try and get as much metal out of the main part of the bay to avoid interfering with the GPS tracker. The bulkheads are CNCed FR4. The nosecone isn't particularly heavy, so I am hoping that 4 pieces of 5/16" nylon holds everything together. If it fails, well, that will answer the question. More likely, if it doesn't work well, the pieces of nylon will deform, start to strip, etc rather than all out failure. If that happens, I will come back later and replace the nylon all-thread with metal.

As noted earlier, in order to ensure I can remove the nosecone bay later (especially if I have to replace that all-thread), it is held into the nosecone with 6-32 PEM nuts.

Heading out to ground test this afternoon.

PXL_20211006_052222199.jpg

PXL_20211006_133733989.jpg

PXL_20211013_211831791.jpg

PXL_20211013_213029863.jpg

PXL_20211013_213622198.jpg

PXL_20211017_081341946.jpg
 

gerbs4me

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Really moving this along now, but had to pause a bit tonight. I was rushing this build and (besides putting the rear fins on backwards!) ran into a number of issues when trying to get the Ebay wired and ready.

First part went well. I put aluminum brackets on either side of the switch bracket to hold it in place and tapped in holes for the standoffs for the Proton and the RRC2. Once that was done, I marked out and drilled the holes in switch band for the switches and vents. All good.

Things went sideways when I started working on the Proton. I had previously assembled and tested the Proton, so that wasn't an issue, but I built it a while ago and had soldered a bridge between the DP+ and B+ pads because I figured I would probably use it in single battery mode. No big deal, get out the solder wick and remove the bridge. Then I soldered JST connectors to the proper pads for both the deployment and logic batteries. Then I installed the board back on the sled and went to attach the leads from the terminal blocks. Here I ran into the next issue - when I assembled the board, I chose to use the green terminal blocks that come with the kit. Frankly, I must have really messed up that soldering job. Of the 12 ports, 9 of the screws would not screw down. I must have melted them or something, who knows. So I took the board off and started trying to de-solder each connection. In doing so, I managed to break one of the terminal blocks off. It didn't damage anything, but it was a lot harder to de-solder. After about an hour of wrestling with the damned things, I finally got one off and all the solder off the board. I cleaned up the pads and soldered 4 wires to two of the channels. I reinstalled the board on the sled and then realized I had put male JST connectors on the battery pads and they needed to be female. And to add insult to injury, I had installed the board with the "UP" arrow pointing toward the aft end of the Ebay and the battery wires would be the wrong length if I turned the board around.

At this point, I was tired and frustrated and realized I needed to walk away for a while. I went and had some dinner, watched some TV, etc, then came back with fresh eyes. I de-soldered the JST connectors, soldered the proper ones on and did a thorough check to make sure I didn't miss anything. I installed the board back on the sled in the proper orientation and proceeded to wire everything up. I finished up wiring the RRC2 and the batteries and the final pictures are below.

Some highlights:
  • Eggtimer Proton with a LiPo for the logic and a 9V lithium for the deployment
  • RRC2L backup with a 9V lithium
  • Nose end bulkhead fixed in place, all wires from those terminal blocks directly wired to the boards
  • Aft end bulkhead removeable, leads have 3M quick connects in the middle
  • All batteries on opposite side of sled from electronics to help protect them if one gets loose
  • LiPo zip tied to sled
  • 9V batteries in modified battery boxes. I remove the switches and hard wire leads to the terminal connectors. Battery box covers are held in place with a screw during flight so the 9V batteries are completely enclosed
  • Pictures show 400 mAh LiPo for testing, actual flights will use an 800 mAh LiPo
Once completed, I did continuity tests and a test ematch fire on all channels.

I hope to get the nosecone bay done later tonight and ground test this tomorrow.

View attachment 486573
View attachment 486574
View attachment 486575
View attachment 486576
View attachment 486577
View attachment 486578
View attachment 486579
View attachment 486580
View attachment 486581
That is one nice avionics bay! I am curious about one thing. Are those screws like switches to turn on/off your electronics?
 

rdrown

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Wow. You know what? They absolutely are on backwards. The wrong edge is tapered. That is how they came from Wildman and I didn't even notice. I was kind of rushing this build a bit because I was hoping to fly this next weekend and didn't even notice the wrong edge is tapered.

I am pretty confident it will fly fine like this, but I guess we'll find out!!
The wrong edge is not tapered. Wild man tapers the leading and trailing edges of dual fins like this.
 

mtnmanak

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That is one nice avionics bay! I am curious about one thing. Are those screws like switches to turn on/off your electronics?
Exactly. The wood switch bracket holds the switches just a milimeter or so away from the edge of the coupler tube, so they are easy to turn on and off. The "on" position is all the way tightened and the "off" position is loosened. Very secure switches.

The logic circuit for the Proton is on as soon as you connect the LiPo battery cable. The switch for that computer is a hard disconnect for the deployment battery. The other switch turns on the RRC2L.

These switches come from Binder design. They include a cool 3D printed backing if you just plan to attach the switch to the coupler itself.


PXL_20211021_235239061.jpg
 

mtnmanak

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Ground test completed.

3 grams FFFFg worked great for the drogue. 4g for the main was slightly less than authoritative. Going to up the primary charge to 4.5g for the flight.

 

Buckeye

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The sled slides onto the bay rails. The rails are 5/16" nylon all-thread. I am honestly not sure how these are going to hold up. First time I am trying nylon. The nuts are made from fiberglass. The intent was to try and get as much metal out of the main part of the bay to avoid interfering with the GPS tracker.
I am no radio guy, but I don't think the metal rods will bother the tracker. I have done a lot of ground/air testing of my trackers with various ebay materials and can't tell a difference between metal vs. no metal.

That said, I was still paranoid enough to consider nylon rods in my last build. 50-100 g loads are thought to be the max force during deployments events. I simulated that (with my body weight!) and the nylon rods held up. Still, I chickened out and went with aluminum rods in my rocket and it tracked just fine.

Awesome build, and let us know how the nylon holds up!
 

mtnmanak

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I am no radio guy, but I don't think the metal rods will bother the tracker. I have done a lot of ground/air testing of my trackers with various ebay materials and can't tell a difference between metal vs. no metal.

That said, I was still paranoid enough to consider nylon rods in my last build. 50-100 g loads are thought to be the max force during deployments events. I simulated that (with my body weight!) and the nylon rods held up. Still, I chickened out and went with aluminum rods in my rocket and it tracked just fine.

Awesome build, and let us know how the nylon holds up!
Will definitely report back on how well the nylon rods hold up!

I am going to try the tracker in some other rockets with metal all-thread as well, so it should hopefully give some good comparison points to post here.

I also want to try one flight with both the Marco Polo and the Featherweight trackers installed. Mainly, it is just an experiment to see if they fly well together.

Hoping to get it in the air tomorrow - looks like no rain and low wind, but possibly low cloud cover :(. 🤞
 

gerbs4me

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Exactly. The wood switch bracket holds the switches just a milimeter or so away from the edge of the coupler tube, so they are easy to turn on and off. The "on" position is all the way tightened and the "off" position is loosened. Very secure switches.

The logic circuit for the Proton is on as soon as you connect the LiPo battery cable. The switch for that computer is a hard disconnect for the deployment battery. The other switch turns on the RRC2L.

These switches come from Binder design. They include a cool 3D printed backing if you just plan to attach the switch to the coupler itself.


View attachment 486701
Awesome, thank you!

I will definitely look into those for my latest project.
 

mtnmanak

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Got a chance to fly the 6" Darkstar Ultimate last weekend on a K1999 and an M1780. Both flights were excellent, but did ID a couple issues.

I used a 24" Skyangle drogue and it was too small. You can see in both videos the booster was WAY above the nosecone/payload bay while under drogue. It didn't cause a problem on these flights, but it obviously could be catastrophic in the future. Will up the drogue to a 30" Fruity Chute Iris next time to see if that is the right balance.

On the second flight, you can see in the video at the end there was an issue with the main chute deploying. It looks like a tangle, but it isn't. What happened was the deployment bag completely ripped out at the end where the pilot chute pulls it off the main and the parachute was pulled through the rip for a couple feet. Luckily, it acted more like a slider - when the parachute fully opened, it pushed the bag off and fully inflated.

The deployment bag is from Skyangle and is the one sold to work with the Skyangle Cert XL chute I used. Post-mortem showed the bag had some really awful stitching at the end. Inspecting the other Skyangle deployment bags revealed the same. I talked to Teddy at Onebadhawk and I am going to have him sew the end closures with Kevlar thread. That should prevent that problem again.

On a positive note, the nylon rods, nylon wing nuts and fiberglass hex nuts in the nosecone worked beautifully! No problems at all - everything looks great. I will keep an eye on them for wear over time, but with two flights logged, no issues yet. Featherweight altimeter worked great (didn't need it, first flight almost literally landed on the pad) and I tried a flight with both the Featherweight GPS and the Marco Polo transmitter - no issues, they did not interfere with each other.

Still need to paint this rocket, but it is officially "done". I will post a finished photo, but I have a couple other projects to finish up before I start the next Darkstar build, so it may be sometime at the beginning of the year before I continue this series.

 
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