Electronics in Nike Nosecone

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COrocket

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Hey TRF,

I think someone asked the question about how to add electronics in a Nike nosecone, and it was a project that I finally got around to, so I thought I'd share. Here is the first batch of pics, more to come tomorrow. As always, questions/comments/suggestions welcome :)

Picture 1: 1/16" G10 Plate CNC drilled for all the electrical components. Dimensions are 2.5" x 7"

Picture 2: Both battery holders are installed, as well as a MissileWorks switch. Both altimeters will be activated from the 4-pole switch. The connections were soldered, and heat shrink tubing cover the switch terminals, due to the close proximity.

Picture 3: Both RRC2-mini altimeters are installed. Also the G10 battery cover is installed, secured with (2) 6-32 screws. Finally, two nylon spacers are attached with West Systems. Their purpose will be explained later.

Picture 4: The nosecone bulkhead and retainer CNC milled to fit the 4" nosecone

Picture 5: Stainless u-bolt installed, and the row of holes seen in picture 4 are tapped to secure the terminal with 6-32 screws. The 8 small holes below it will be where the wires will run through.

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Picture 1: Here is how the two aluminum components fit together. They will be attached using (8) 8-32 screws that are radially spaced.

Picture 2: The retainer is permanently glued into the nosecone shoulder of the rocket.

Tomorrow the electronics board will be connected to the nosecone bulkhead!

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Looks like very nice work. If you need vent holes it always the big question as where to put them on a Nike Smoke. I have a PR 5.5 NS but have not flew it yet. I am not sure where to vent the ebay?
Thanks
 
Beautiful aluminum and G10 work.

I would, however, discourage the use of a single switch to arm each altimeter. You chose to have redundant altimeters, therefore I would personally make the two completely independent of one another.

If you switch fails, your rocket lawn darts.
 
I would, however, discourage the use of a single switch to arm each altimeter. You chose to have redundant altimeters, therefore I would personally make the two completely independent of one another.

^This. :D



Justin
 
Beautiful aluminum and G10 work.

I would, however, discourage the use of a single switch to arm each altimeter. You chose to have redundant altimeters, therefore I would personally make the two completely independent of one another.

If you switch fails, your rocket lawn darts.

Thanks, I thought about that after I started building (that relying on a single component for both altimeters sort of defeats the purpose of redundant systems). I will have to put in an order with missileworks tonight, but I will probably fly the rocket as is for this weekend. I was going to do the full DD setup, but since this is the first flight of both altimeters, I am just going to do single deploy, with the CTI delay grain left at full length as a backup. I will experiment with releasing the parachute with a tether on the flight after that.
 
Here's another update for tonight:

Picture 1: Here all of the wires running through the bulkhead are glued in their holes, and secured to the terminal block. There is an 8 position terminal block, that allows for both altimeters main/backup charges to be hooked up.

Picture 2: Here is the wiring on the other side, now running up through holes in the altimeter sled

Picture 3: The wires hooking up to the end of both altimeters. If you are wondering why I bothered running the wires under the board and then through the bulkhead, it was simply to keep them out of the way when I was tightening the nuts on the u-bolt.

Picture 4: How the finished assembly looks mounted in the nosecone!

I spent the rest of my time drilling the arming/vent holes, as well as shear pin holes. All that is left is to size and test the charges tomorrow for saturday's NEFAR launch :D

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Looks like very nice work. If you need vent holes it always the big question as where to put them on a Nike Smoke. I have a PR 5.5 NS but have not flew it yet. I am not sure where to vent the ebay?
Thanks

To answer your question, I just put the vent holes as far down the tube as possible (while still venting the nosecone, which for me was 3" from the top of the body). I attached the picture of how i did mine. I am going to utilize 3 vents, each 3/16" diameter. I was a little generous for the hole size, but it is pretty close to the sizes recommended in the missileworks manual for 3 holes venting a nosecone with about 150 in^3 of volume. The one vent hole on top is farther up the tube because it is also a switch arming point.

Anyways, some minor preparations were done today to get ready for launch. Shear pins were added, 4 sec mach delay set (even though it wont go supersonic) and the hole in the bottom of the tender descender was slightly enlarged to fit two Q2G2 igniters through. The plan tomorrow is to use motor ejection at apogee to separate the rocket, then to deploy the main at 1000' using the tether. The only reason for the motor eject is because i didn't have time to ground test with electronic activated charges and shear pins. So for tomorrow it will be a friction fit nosecone and motor deploy, the only thing different will be the main deployment. Hoping to launch on a J350W, J420R, or maybe even a J500G

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I'm VERY anxious to know how the vent hole worked out for you in that location. I'm doing the same thing with my N.S. although I don't have access to a milling machine so my av-bay is good ole' plywood.

I had the same concern about the vent hole being far enough down to avoid any disturbed airflow coming off wide point on the nose-cone.

Did you get accurate readings?
 
I'm VERY anxious to know how the vent hole worked out for you in that location. I'm doing the same thing with my N.S. although I don't have access to a milling machine so my av-bay is good ole' plywood.

I had the same concern about the vent hole being far enough down to avoid any disturbed airflow coming off wide point on the nose-cone.

Did you get accurate readings?

Attached is a graph of inertial and barometric altitude-time curves for a large scale Nike Smoke. The vent hole is well within the downwash of the over-wide nosecone, and anomalies are present in the barometric data. The anomalies are confined to the boost phase, however. The rocket slows down as it approaches apogee, and the two curves come together rapidly. Inertial and barometric estimates are indistinguishable at deployment. IOW, the instrument took bad data, but deployment wasn't affected.

There are at least two hazards:

1) It’s *possible* for the downwash to get so bad that the barometric altitude drops from a high-pressure region engulfing the static port. In that case, early deployment could occur. I’ve never seen this sort of thing on a subsonic flight, but… who am I?

2) If the flight is extremely off-vertical, because of some untoward event, the thing could be going very fast at apogee. The chances of that are small, and the chance of a malfunction because of bad data should it happen are even less likely.

This post is for entertainment value only. No warranty, express or implied, is made. Void where prohibited. Keep out of reach of children, and do shake well before using.

-LarryC

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Attached is a graph of inertial and barometric altitude-time curves for a large scale Nike Smoke. The vent hole is well within the downwash of the over-wide nosecone, and anomalies are present in the barometric data. The anomalies are confined to the boost phase, however. The rocket slows down as it approaches apogee, and the two curves come together rapidly. Inertial and barometric estimates are indistinguishable at deployment. IOW, the instrument took bad data, but deployment wasn't affected.

There are at least two hazards:

1) It’s *possible* for the downwash to get so bad that the barometric altitude drops from a high-pressure region engulfing the static port. In that case, early deployment could occur. I’ve never seen this sort of thing on a subsonic flight, but… who am I?

2) If the flight is extremely off-vertical, because of some untoward event, the thing could be going very fast at apogee. The chances of that are small, and the chance of a malfunction because of bad data should it happen are even less likely.

This post is for entertainment value only. No warranty, express or implied, is made. Void where prohibited. Keep out of reach of children, and do shake well before using.

-LarryC

So which motor did you end up using? Also how did you set up your dual deploy?
 
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I'm VERY anxious to know how the vent hole worked out for you in that location. I'm doing the same thing with my N.S. although I don't have access to a milling machine so my av-bay is good ole' plywood.

I had the same concern about the vent hole being far enough down to avoid any disturbed airflow coming off wide point on the nose-cone.

Did you get accurate readings?

I did end up flying the rocket a few days ago, but I did not utilize the electronics. The reason is because it has rained here so much that there was places of standing water on the field. (If we are not in a drought we are fighting the excess rain :eyeroll: ) I didn't want to risk ruining the altimeters if it landed in a puddle. Unfortunately, I only have basic RRC2s, so i will not be able to make a nice plot like Larry did above. I will only know if it worked or not. I will keep everyone posted, and I'll get some schematic pictures up shortly.
 
Whoops! Sorry, I see that now...

What was the source of your data then? Was the vent hole similarly placed?

A friend sent me his data. I presented it anonymously. I can ask his permission to mention his name if you like. (I have permission to use it in an R&D report.)
 
Sorry it took so long, but here are some final build photos...

Photo 1: I forgot to take a picture of the electronics board, but I did take the advice of patelldp and installed a second switch. Photo 1 shows the extra vent hole drilled to arm the second switch.

Photo 2: There is a bit going on here, so i will try to explain as simply as possible. The two wires taped together in the far back are the apogee charges. They run all the way to the centering rings, pushing the nosecone off at apogee. The thick Kevlar cord is the shock cord, keeping both the fin can and the nosecone together for the entire flight. This is photo shows how the rocket will fall, drogue-less. The chute is wrapped in a nomex protector, held together with the Tender Decender. The TD is attached to the nosecone via the thin Kevlar cord. The two main charges (taped together to reduce the chance of tangling) are tied to one of the quicklinks on the TD, to make sure that there is no tension on the e-matches where they enter the TD chamber. At main AGL, the TD fires, and the parachute unfolds...and thats about it. I will get pictures up when i get a chance to launch

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They run all the way to the centering rings, pushing the nosecone off at apogee.

Is it really important where you place the charge? I went with .5" PVC end caps, as charge cups, and placed them on the bulkhead at the base of the nose cone. I was planning on just wiring the charges from the altimeters through the bulkhead.
Anyway, I thought it was mostly the pressure that pushes everything out, rather than the force of the charge?

Don
 
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Well, i choose to run the charges to the bottom, so that they push the nosecone and the parachute out. If they were on the bulkhead, the charge might push the parachute back towards the bottom of the rocket (its a pretty good fit in the body tube) while the nosecone goes in a different direction. I realize the whole point of the charge is to pressurize the compartment, so im not sure how much it matters where the charge goes off.

If someone else has more experience with something like this, they might have a better answer. I usually do zipper-less designs in more traditional rockets, where both the drogue and main are pushed away from either side of the electronics bay, in which case the charge caps work fine. Tether recovery is new to me for this project :rolleyes:
 
Well, i choose to run the charges to the bottom, so that they push the nosecone and the parachute out. If they were on the bulkhead, the charge might push the parachute back towards the bottom of the rocket (its a pretty good fit in the body tube) while the nosecone goes in a different direction. I realize the whole point of the charge is to pressurize the compartment, so im not sure how much it matters where the charge goes off.

If someone else has more experience with something like this, they might have a better answer. I usually do zipper-less designs in more traditional rockets, where both the drogue and main are pushed away from either side of the electronics bay, in which case the charge caps work fine. Tether recovery is new to me for this project :rolleyes:



My $0.02: see this thread regarding using charges above the laundry - Ground tested apogee charge...help!

Hope it helps!
 
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