Level 2 Project - Another Darkstar 3 Build

[NateB]

First set of external fillets are applied and shaped. It thickened up faster than usual and I'll have a little clean up work before I paint. I can touch them up when I shape the next set. I can also sand and fill them with Bondo putty before I paint. With the strong fin pockets, this is only cosmetic.

 

[NateB]

I was able to finish the external fillets this afternoon and the last set is curing now.

I also ordered a second set of stepped bulkheads from Wildman so the nose cone coupler can also be used as a payload bay.

 

[NateB]

I updated my sim file in Open Rocket and noticed it appears to be adding the mass from the override on the stage to the total rocket rather than overriding it completely. Current weight with no motor, recovery, electronics, or paint is about 6.5 pounds. I ordered the recovery package from Rocketman. I'm getting close to ground testing the ejection charges before I start painting.

 

[NateB]

This was view this morning at work.



After I completed required tasks for the day, the rest of the time is ours in between calls.

I spent some of it going from this:



To this:

 

[NateB]

Preliminary testing of the TRS appears to be successful. I plugged in a battery and it immediately powered on, paired with my LCD Receiver, and the amber light shows it captures satellites.

I still need to hook it up to my computer so I can reset the memory and give it a name. I'm hoping I can use it for ground testing the charges soon. It will be more convenient using the altimeter instead of fishing wires through vent holes and to my Cobra system.

 

[NateB]

I'm having trouble getting the Eggfinder LCD to flash updated firmware with my Windows 11 computer. Hopefully I can get that to work, but if I can't the TRS still syncs with it as expected.

Another bump in the road was the holes on the 3" sled I have from Additive Aerospace doesn't match up with my TRS and the thicker area with the pilot holes is just too short to drill more holes. There must have been a change in the TRS board since whenever my sled was made.

I opened up Tinkercad and started working on a basic sled for this rocket. I haven't used CAD software before, so this is a good chance to learn with simple shapes. I printed a draft with just the lower half to make sure the batteries and rods fir. So far, so good. I'll work on the band at the bottom and print the full sled in higher quality later.

 

[NateB]

I worked on the bulkheads for the AV bay this evening. I left room to mount an external antenna if needed, but I might route it behind the TRS and keep everything inside the coupler. The threaded charge wells help everything look nice and clean and also have a low enough profile they fit well in the nosecone for HED.

 

[NateB]

I tried to update my Eggfinder LCD again with no luck. For some reason the LCD just won't flash with Windows 11. No matter what I do, it powers up and loads as normal. The same USB dongle works with my TRS and Eggfinder Mini, so its probably something to do with my LCD. I gave up and put everything back in the case.

When I tested the TRS at first, everything looked great. It syncs with my LCD and shows continuity with the ematches. The first deployment test wouldn't fire either side. I'm using the same 2 cell batteries that work with my other devices, so I know the batteries work. I double checked all the connections on the optoisolators and soldered a tiny bit more to make sure each pad had a good joint.

Finally, the TRS showed good continuity and fired a match on both channels with the deployment test and vacuum testing. I'd like to test the GPS outside before I fly it, but it did show coordinates for my house on the screen.

 

[NateB]

I think I have the sled for the TRS just about complete. If the antenna doesn't work on the sled, I'll move it to the lower bulkhead so it is exposed to the atmosphere with drogue deployment. I'd like to keep everything inside if I can. The places I can launch have 12,000 - 16,000 ft waivers, so I don't anticipate being crippled by reduced range. An I motor for the first flight and a J-474 motor I'm planning on for my L2 attempt shouldn't go so high that I need to rely on the tracker anyway.

 

[cautery]

Nice.... hope it works for you. Antenna stuff can be weird and funky at times....
If I were you, I would twist those power leads.... 3 per inch if you can.... No parallel power or signal wires anywhere that aren't twisted pair.

 

[DRAGON64]

That is a nice and clean 3D printed sled, very nice!

 

[NateB]

Nice.... hope it works for you. Antenna stuff can be weird and funky at times....
If I were you, I would twist those power leads.... 3 per inch if you can.... No parallel power or signal wires anywhere that aren't twisted pair.

Thanks for the reminder. I'll definitely twist the power leads when I finish up the wiring. Their will already be some interference and no need to add more. I might drive around and test range today or tomorrow.

That is a nice and clean 3D printed sled, very nice!

Thanks!

 

[NateB]

My AV bay is complete, as long as I still get a good signal with the antenna in this configuration. If I don't get a decent amount of range, there is room to mount the antenna on the drogue size bulkhead.





After ground testing to confirm the ejection charges, there's no reason this rocket can't fly.

 

[NateB]

Getting back at this one. The extended forecast looks great for painting, so I really want to do some ground testing before I lay the final color coats on. I spent a few minutes this evening practicing packing the parachutes and deployment bag for the main.

This is also the first time I have had the full stack assembled with all of the recovery components installed. I know others have thought this the first time they built a similar project, but it does feel big compared to everything else I have built. My wife's first comment was "you can't possibly be planning on launching that at the park."

 

[NateB]

I spent some more time packing and repacking the recovery in various configurations. I was able to get the main in the nosecone for HED. There is not much room to spare, but it is not jammed packed either.

I will have to make some careful notes for the CP/CG changes and the ejection charges next. I am happy to have a 3" rocket that can fly in 3 different configurations for different field conditions.

 

[NateB]

I did some more testing with my TRS today. I bench tested it after assembly, but today was the first time I tested it in the AV bay configuration without any BP in the wells. Both matches in the drogue and the main popped as expected, so no shorts with the aluminum bulkheads and charge wells. I think I am going to start testing with 1.5g of 4fg in the drogue and 1g in the main and work from there.

I was thinking about the first flight. For the full dual deploy stay, the I-405 sims to 1732 feet. That seems perfect. I would be able to easily see each event. For my L2 cert flight, I am still planning on a J-474 which the sim shows 2871 feet. If I take out the payload and AV bay, I can even fly this on an H-160 and motor deployment estimated at 953 feet. Even though I built this heavy, one could use this kit for their L1 and L2 certs with simple planning.

 

[Glasspack]

Nate, What does your model weigh?

 

[NateB]

Nate, What does your model weigh?

It weighs 8lb 4oz without the motor and before paint.

 

[Glasspack]

It weighs 8lb 4oz without the motor and before paint.

Thank you. I have been worrying
about my LVL 2 Cardboard Model which is over 7 lbs

 

[NateB]

You're welcome. I think I'll end up between 10.5-11lbs ready to launch on a J motor. It should make for a good flight to see everything and easy recovery.

 

[NateB]

I was able to get some ground tests done today. I started with some amounts calculated using the tool here: https://rocketrycalculator.com/rocketry-calculator/bp-estimator/

Both the drogue and the main were were secured with one 4-40 shear pin. I might try another round of testing using 2 each before I finish the paint job.

1.7g 3Fg for the drogue was just right.



0.8g popped the nosecone and ejected the main, but it needs a little more. 1.0g - 1.2g will likely be the sweet spot.

 

[Hobie1dog]

1 gram seems to be a sweet spot for lots of rockets

 

[Wrightme43]

Nate, How did it fly sir?

 

[NateB]

Nate, How did it fly sir?

Still working on finishing, paint takes forever. I was hoping to fly it this winter. We have to fly in the snow in the Midwest while the fields aren't planted.

 

[Wrightme43]

I really like the Dark Star. It is a beautiful rocket that just looks fast!

Thank you for the effort you put into this build thread. I have learned a tremendous amount from the people who take the time and effort to show why they build things the way they do.