Estes Nike Smoke NC Altimeter Bay

My Estes Nike Smoke is structurally complete, and I figured I'd share the altimeter bay setup I'm using. I knew that I would be pushing this rocket hard and high, and figured it made sense to use Dual Deploy. But, with its short stature, there really is no room for the motor, av-bay, and payload section. So, I decided I would go with a NC altimeter bay and cable cutter DD.

I cut off the very bottom of the estes NC, and replaced it with a stepped plywood bulkhead:




I needed a way to mount allthread, so I made a bulkhead out of some plywood, epoxied some 3/16 allthread, and associated hardware onto it, and then epoxied that into the NC, so that the allthread would run aft towards the bulkplate.




I made up a sled out of the same plywood, and installed T-nuts for mounting the altimeter (RRC2+), drilled holes for zip ties for the battery, and cut out some mounting plates (technical term?) for the battery similar to what madcow uses on their sleds.
I decided I would try out one of the screw switches from Missileworks, but since the switch naturally needs to be mounted in the center of the sled, I mounted it on a little standoff so it would be above the allthread.





The sled slides right into the cone on the allthread, and the screw switch is close-ish to the inside of the cone, so arming is fairly easy






The bulkhead slides on, and away we go!



The 3rd hole is a wire pass through for the cable cutter.
Does anyone have suggestions about lengthening the e-match wires? for instance, the e-matches I use are about 9" long, but If I wanted to attach another 6" could I just solder on leads?

So that's my setup, comments, suggestions?

Nate

Can't believe I just saw this now but it looks pretty good. Only worry I have is having the one piece of allthread that is off center. 'm worried deployment could break the plywood. But it should work

Thanks, The plywood is 3/8", so it seems pretty strong, but I've never used just 1 allthread before. Do you think it would be any stronger if I used an eye nut on the allthread, rather than a separate eye bolt?

Nate

nute said:

Thanks, The plywood is 3/8", so it seems pretty strong, but I've never used just 1 allthread before. Do you think it would be any stronger if I used an eye nut on the allthread, rather than a separate eye bolt?

Nate

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It would probably be stronger, however I'm sure it'll be fine as long as you did a good job epoxying in the all thread.

codysmith said:

It would probably be stronger, however I'm sure it'll be fine as long as you did a good job epoxying in the all thread.

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Cool, first flight should be next week, depending on the weather...

Nate

Did this fly? If so, how'd it work?

Yeah, it flew at our March launch. The results were... troubling.

The bay held up great, and nothing that shouldn't have separated did separate. However, somewhere between the altimeter and the parachute opening there must have been a bit of a miscommunication. I prepped everything at home, sans wiring the altimeter (I was using it in another rocket that would fly first). And, when I went to do that I must have bumped the leads of the ematch (already inserted into cable cutter) into the battery terminals. I was fine, and managed to retain all my fingers (luckily my hand wasn't physically on the cable cutter at the time, but I had to repack everything, and boy did that give me a shock! After fighting with the cable cutter to get the cutting head out, I finally got everything put back together. The altimeter armed fine, and beeped out everything nominally on the pad. The boost was great, with the G64 giving it a nice ride to an altitude I can't remember right now... However, when the motor ejection charge fired, out popped the itty-bitty drogue, and also the much larger main :y: There was no evidence of a cable-cutter firing on the way down. No smoke, pop, nothing. Upon recovery (luckily it was a calm day) I found that I had, in fact, wired the cable cutter to the main terminals, ruling out the altimeter firing it as the drogue charge. There were also exactly three burn marks on the brand new parachute protector. One from the ground test, one from the, uh, unplanned ground test, and the last one had to be from the flight. This means that the cutter must have had to be fairly close to the burrito when it fired, which points to an early main firing by the altimeter. I also looked through the video, and played with the audio in Audacity, and there is most definitely no second charge on the way down. There are, however, two little "blips" in Audacity at the apogee deployment. The motor e-charge, and a cable cutter? Maybe. Unfortunately, I forgot to retie the cable cutter to the NC when I repacked it, so I'll be ordering another one of those soon...

After mocking up the setup at home, and tying the burrito to the end of a bit of Kevlar, it took me about a half dozen hard swings to get the parachute to pull out of the burrito. Could this force have been replicated right at apogee deployment? Personally, I doubt it, and I'm guessing the altimeter fired early. Going forward, I plan to enlarge the vent hole, and try again. Any suggestions are welcome

Video:
[video=youtube;2HIlqg1S8y0]https://www.youtube.com/watch?v=2HIlqg1S8y0[/video]

Nate

I flew this rocket again yesterday at METRA with the cable cutter. The flight was just about perfect! The H128W launched it up beautifully to just under 1900 ft, gotta love that motor for $13 on Black Friday! I used a 9" drogue tied about 4 ft. down the cord, and a 30" main wrapped up with the cable tie on about 18" of kevlar off of the NC eye bolt. At apogee the drogue opened up nicely, and the main seemed to stay pretty under control. Then, right on cue at 500 ft. the cutter cut, and the main opened right up. Unfortunately, it proceeded to drift into a tree... hanging over a river... So that's not ideal... Anyway, the altimeter, tracker, cable cutter, motor case and closures are all in limbo right now. Well, it's the risks we take in this hobby. Hopefully the resident tree climber will be able to lend a hand.

Video up soon.

Nate

Congrats. Glad you got that sorted out. I'd suggest that you use an eye nut as opposed to an eye bolt, that way if something does break, you just lose the nose cone instead of the nose cone and altimeter.

Tonimus said:

Congrats. Glad you got that sorted out. I'd suggest that you use an eye nut as opposed to an eye bolt, that way if something does break, you just lose the nose cone instead of the nose cone and altimeter.

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Thanks, during the build I did a bit of poking around and couldn't find a good source of eye-nuts. If I ever get it back I might do some more looking.

Nate