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What would you do?
#1
Question 
I have been building a Wildman Dark Star 2.6" kit for months now.  A little bit here and there.  Getting near done.

It has the polycarbonate nose cone with a FG coupler.  Being excited and not thinking when I got it, I shoved the coupler in.  It's a glue-free coupler, and not designed to come out.

But since this sucker is going to go Mach 1 and probably close to 10k feet, I want to put my GPS tracker in the NC.

I have two choices:
  1. Try to pull out the coupler, then put an inside bulkhead on one end and a removable outside bulkead on the other head, held together with all thread.
  2. Finish assembling the NC with the single outside bulkhead, then use a Dremel and a cutting wheel to cut a door in the NC shoulder.
Here are what I see as the advantages of each.
  1. This is probably the recommended way, and results in more stability, and safety for the tracker.  But it could break the NC or the coupler if I try to pull the coupler out.  Also, I would have to put metal in the NC, which could interfere with the tracker.
  2. This is quicker and easier, and this is what I do with my MAC Perf Scorpion (but it has a plastic NC).  The tracker can roll around in there, and could potentially fall out of the door if things get really rough.  But I don't have to buy a bulkhead or additional allthread.  However, I'm not sure how good I would be at cutting the coupler.
So I am wide open to ideas.  Thanks.
John S.
NAR #96911
TRA #15253
MDRA
Level 1, 2014-Mar-15 -- Aerotech Sumo, H133BS
Level 2, 2014-Jun-21 -- Giant Leap Vertical Assault, J240RL
Level 3, 2016-03-12 -- MAC Performance Radial Flyer, M1101WH, 13,028 feet
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#2
I would try and take the coupler out. If worse come to worse, you can always buy a new coupler. Or try explaining your file a to Wildman and see what he recommends.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
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#3
(10-29-2015, 12:30 PM)Bat-mite Wrote: Try to pull out the coupler, then put an inside bulkhead on one end and a removable outside bulkead on the other head, held together with all thread.

I built a 3"  Darkstar last winter, the one that comes with a FW/FG nosecone and the aluminum tip.  I wanted to shed some forward weight so I ordered the polycarbonate nose cone with a FG coupler from Wildman, so same setup as you.  I designed the nosecone very close to what you described in your option 1.  I also ordered a 54mm MMT from PML and secured it to the aft bulkhead which removes as one piece and that is where my trackers slide into.  The trackers mount back to back on a G10 board which runs the length of the MMT so there is no wiggle room.

One thing I did to mitigate metal in the nosecone was to remove the nosecone tip screw.  To keep it in place I slotted the sides of the shoulder part of the tip then epoxied it in so it is permanent.  Also the screws I used to secure the bulkhead/MMT assembly to the nosecone internal ring are as short as possible, 3/4" 4-40.  To secure them I epoxied PEM nuts into the internal ring.  The internal ring is not up behind the nosecone shoulder, it is epoxied into the coupler with a well bonded fillet below it.

I purposely moved the mounting ring further aft just to mitigate the length of the screws, all in an effort to keep as much metal away from the trackers as possible.  Also I did not use a U or eye-bolt for securing the recovery harness  Instead I drilled some holes in the bulkhead and pushed some Kevlar through the hoes then epoxied the Kevlar to the 54mm MMT tube.  Even if the MMT bond failed the Kevlar is epoxied flat and will not go back through the holes, so effectively it's more just to keep it neat than anything else.

So obviously I am a fan of option 1.

If you want any pics to clear up my explanation then just let me know.
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#4
John, my L3 NC had the same problem. I unscrewed the tip and used a 1/2" wooden dowel and tapped the coupler evenly around the edges from the top, after about 3-4 minutes it came out, didn't damage the coupler at all.
Dave Greger L3
NAR# 95846
MDRA #65

Hollie L1
NAR# 99687
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#5
Sadly, mine's a one-piece with no aluminum tip. Tim said to leave the coupler in, so that's probably what I'll do. Also, I might be visiting Scott S. soon, and I will see what he thinks.
John S.
NAR #96911
TRA #15253
MDRA
Level 1, 2014-Mar-15 -- Aerotech Sumo, H133BS
Level 2, 2014-Jun-21 -- Giant Leap Vertical Assault, J240RL
Level 3, 2016-03-12 -- MAC Performance Radial Flyer, M1101WH, 13,028 feet
Reply
#6
1. Place nose on side with the coupler hanging off a sturdy table or bench
2. Place one hand on the cone section, one hand on the coupler
3. Using the edge of bench as your fulcrum, press down on the coupler while pulling the coupler at the same time.
4. Rotate the cone and do this again..push down and pull out

You're effectively rocking the coupler out...there should be a little bit of play that will permit this to work.
Dan Patell
TRA 10904 L3
Patell Manufacturing Facebook Page
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