Dave47's Macdow 5.5" Black Brandt II Build for L3 Cert

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Today's updates will be about the electronics bay. I needed to get this part put together so I could start ground testing the ejection charges. Also, I don't have a complete step by step guide from here since how I get from point A to point B should be self explanatory. (if not, just ask.) So, here we go...

This kit comes with a 2 inch switchband. I decided I wanted an access hatch instead of a couple of holes in the switchband. So, I cut one out.
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I also slit the switchband so that I can pry it open a little when epoxying it in place. This is an alternative to putting some epoxy on the coupler and pushing the switchband into it. I always had too much glue pile up at one end. This keeps that from happening. A little fill and sanding work will need to be done, but that shouldn't be a problem.
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Skipping ahead a few steps... I have epoxied the switchband on with the Proline 4500 epoxy. It is a little thinner and easier to spread than the rocketpoxy. I have also cut the access hole in the coupler and installed all of the PEM nuts for the access hatch and the payload section. I used 4-40 screws for the hatch and 6-32 screws for the payload section.
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From the inside, you can see how complete the epoxy coverage is between the switchband and the coupler. I have also put epoxy over each of the PEM nuts so they don't fall out. I retapped all of the PEM nuts in case any epoxy got in there.
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And with the hatch secured.
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Next, I bolted the two end caps for the electronics bay together so that I could decide where to put the charge wells and the terminal strip. This kit came with aluminum end caps with stepped edges, which is very nice to drill. The charge wells and terminal strips came from Doghouse Rocketry some time ago. They are the 6 gram wells, but I don't think I am going to need near that much powder.
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Hmmm, I almost lost the last post due to an unresponsive server. I'm glad I don't have to retype it. Anyway...

I marked and drilled all the holes. The two end caps are mirror images of each other now.
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I then attach the charge wells and terminal blocks. I also drilled 4 small holes for the four wires from the electronics. They are slightly larger than the wires that will be inserted in them. I will be covering these with hot glue (or something else that is removable. I haven't decided) to seal them from ejection gasses.
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Finally, here is the sled for the electronics. On the left is an Eggtimer Quantum. I chose this one so that I can do the ground testing wirelessly. The battery is a 2S 370mAh LIPO. On the right is a Raven 3. It is the primary altimeter. I have used it many times already (L1 and L2 and other launches). It has its standard 9V battery. Don't worry... I will be using a Duracell for the actual flight. This one was available for testing. I also knocked together a terminal block for the Raven 3 that just breaks out the drogue and main terminals. The switches for both altimeters are from Fingertech Robotics.
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I haven't shrink wrapped and color coded these yet, but they will connect the electronics to the terminal strips. They are standard 12 inch 4 pin ATX connectors that you can buy pretty cheaply. I cut the ends off of them and get four terminal locking connectors with plenty of length work with.
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Next up will be to drill the three vent holes in the switchband and a vent hole in the booster and the payload section. I also need to finish up the nose cone tracker bay, but that too is almost done. I need more to post photos.

David
 
Hmmm... I kinda got busy and flew this rocket at Airfest and never completed this build thread. Suffice to say everything went well and my certification was received. If anyone has any further interest in the finishing touches of the build, let me know and I can add them to this thread. Otherwise, I apologize for the abrupt end.

David
 
Hmmm... I kinda got busy and flew this rocket at Airfest and never completed this build thread. Suffice to say everything went well and my certification was received. If anyone has any further interest in the finishing touches of the build, let me know and I can add them to this thread. Otherwise, I apologize for the abrupt end.

David

I'd like to see photos of the finished rocket and cert flight.
 
As requested...

Picture of me next to the BBII on the pad and ready to go...

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Link to the YouTube launch video from the ground...

[video]https://youtu.be/Pnnr2w1wKCk[/video]

Link to the YouTube video from the onboard camera...

[video]https://youtu.be/q3m3SQMs60g[/video]

Lots of spinning on the way down, but I had one of the large swivels right at the top of the booster, so the shock cord wasn't all twisted up when it landed.

Picture of it all back on the ground...

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Thanks again for looking!

David
 
Cool images / videos. I think I heard the LCO say 9500' estimate - what was the actual altitude?

It only made about 7300 feet. I had a lot more drag than I simulated between the camera and the taped nose (to cover the metal tip I didn't get painted.) I'm sure the rough fiberglass finish didn't help either.

David.
 
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