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Best way to 'finish' a LOC nosecone?
#1
Like most of you, I have had awful luck with eyebolts screwed into the existing shoulder base or using the plastic loop to retain LOC nosecones.  I have tried a few ways to overcome this and retain a LOC nosecone in a high powered rocket.  It's frustrating enough that I usually try to go with a FG nosecone when I can--so much easier, it seems to me.

I am working on a 4" scratch build and have a LOC nosecone.  I sawed off the bottom of the shoulder base, so the cone is fully exposed.  I need to put about 8oz into the nosecone tip as well as retaining it.  Any suggestions on how best to work it from here?
Mark Rose
Tripoli Vegas
TRA #11717 L3
KG7NWI
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#2
(07-02-2015, 12:20 AM)Stealthfixr Wrote: Like most of you, I have had awful luck with eyebolts screwed into the existing shoulder base or using the plastic loop to retain LOC nosecones.  I have tried a few ways to overcome this and retain a LOC nosecone in a high powered rocket.  It's frustrating enough that I usually try to go with a FG nosecone when I can--so much easier, it seems to me.

I am working on a 4" scratch build and have a LOC nosecone.  I sawed off the bottom of the shoulder base, so the cone is fully exposed.  I need to put about 8oz into the nosecone tip as well as retaining it.  Any suggestions on how best to work it from here?
I cert'd L1 and L2 with plastic NCs.
Since you have already removed the bottom of the shoulder base, it will be easy to fill the tip with epoxy coated lead shot to give you the desired weight you are aiming for. For adherence you can mount a small dowel horizontally by drilling through the sides of the NC near it's tip.
If you are really compulsive about that sort of thing you can mount a second dowel perpendicular to the first, so you have a 90 degree cross arrangement of your 2 small dowels.
Once the epoxy and weight set up, cut/file off and then sand down the projecting ends of the dowel(s), and you will never know they were there!
For the base of the NC shoulder, cut out a plywood disk, and install an eyebolt (all of mine are welded eyebolts bolts, so there is no change of the bolt being torqued open), washer, and nut. Add a little epoxy to the nut to prevent it loosening, and secure the bulkhead (disk) to the shoulder.
Then go and fly it! Smile
Greg Young - L3
TRA 00234
NAR 42065
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#3
(07-02-2015, 08:06 AM)Greg Young Wrote:
(07-02-2015, 12:20 AM)Stealthfixr Wrote: Like most of you, I have had awful luck with eyebolts screwed into the existing shoulder base or using the plastic loop to retain LOC nosecones.  I have tried a few ways to overcome this and retain a LOC nosecone in a high powered rocket.  It's frustrating enough that I usually try to go with a FG nosecone when I can--so much easier, it seems to me.

I am working on a 4" scratch build and have a LOC nosecone.  I sawed off the bottom of the shoulder base, so the cone is fully exposed.  I need to put about 8oz into the nosecone tip as well as retaining it.  Any suggestions on how best to work it from here?
I cert'd L1 and L2 with plastic NCs.
Since you have already removed the bottom of the shoulder base, it will be easy to fill the tip with epoxy coated lead shot to give you the desired weight you are aiming for. For adherence you can mount a small dowel horizontally by drilling through the sides of the NC near it's tip.
If you are really compulsive about that sort of thing you can mount a second dowel perpendicular to the first, so you have a 90 degree cross arrangement of your 2 small dowels.
Once the epoxy and weight set up, cut/file off and  then sand down the projecting ends of the dowel(s), and you will never know they were there!
For the base of the NC shoulder, cut out a plywood disk, and install an eyebolt (all of mine are welded eyebolts bolts, so there is no change of the bolt being torqued open), washer, and nut. Add a little epoxy to the nut to prevent it loosening, and secure the  bulkhead (disk) to the shoulder.
Then go and fly it! Smile
I have done the same but used bamboo skewers instead of dowels.  Depending on the size of the rocket and nose cone,  one or the the other would be appropriate.

I've heard of rocketeers using Gorilla Glue and a bit of water to accomplish the same results as epoxy to anchor the ballast inside the nose cone but have never tried this method but it's out there if you want to investigate more.

In terms of attaching a bulkhead to the inside the nose cone, I've used the John Coker method and I've also anchored bulk plates using through the nose cone wall screws followed up with epoxy fillets. Neither have given me any cause for concern so far.

I'd recommend roughing up the interior surface of the nose cone regardless of the method you finally decide to use.  By roughing I mean actually raising up fuzz or "hairs".  The sharp end of a rat tail file will do this nicely.
Kit (aka "Cranky Kong"), Certified Rocket Monkey
"We were promised jet packs!"

2015: Total Impulse: 2,017.78 Ns - 58% K motor
Since 2010: Impulse: 11,019.58 Ns - 8% N motor
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#4
+1 on the use of dowels or skewers. Simply roughing up the interior of the NC is not enough for the epoxy to stick.
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#5
I have used brass rods with great success. They are easily cut and sanded and you don't have to worry about them breaking off.
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#6
+1 the brass rods, like the bamboo skewers they are easy to sand flush with the plastic. I also highly recommend using an adhesion promoter (Duplicolor makes my favorite) with all plastic NCs, since using it the chipping of paint has been almost totally eliminated on my NC's (except of course hitting rocks).
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#7
(07-04-2015, 02:03 AM)rharshberger Wrote: +1 the brass rods, like the bamboo skewers they are easy to sand flush with the plastic. I also highly recommend using an adhesion promoter (Duplicolor makes my favorite) with all plastic NCs, since using it the chipping of paint has been almost totally eliminated on my NC's (except of course hitting rocks).

Thanks for the tip.  I added a can to my Amazon shopping cart.

I have a Madcow Squat that has an alarming tendency to chip in the same spot every time I fly it and I'm growing tired of the sand, spray, overcoat routine.
Kit (aka "Cranky Kong"), Certified Rocket Monkey
"We were promised jet packs!"

2015: Total Impulse: 2,017.78 Ns - 58% K motor
Since 2010: Impulse: 11,019.58 Ns - 8% N motor
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#8
An easy method to keep ballast at the tip of the cone is to spray expanding foam into the nose cone. And a little goes a long way!
Lee
NAR 55948, L2
In Build: Mars Snooper
Next: upscale Sky Hook (Panavia kitbash)
In Finishing:  Estes Honest John, Red Nova, Super Cobra
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#9
(07-04-2015, 01:48 PM)CrankyKong Wrote:
(07-04-2015, 02:03 AM)rharshberger Wrote: +1 the brass rods, like the bamboo skewers they are easy to sand flush with the plastic. I also highly recommend using an adhesion promoter (Duplicolor makes my favorite) with all plastic NCs, since using it the chipping of paint has been almost totally eliminated on my NC's (except of course hitting rocks).

Thanks for the tip.  I added a can to my Amazon shopping cart.

I have a Madcow Squat that has an alarming tendency to chip in the same spot every time I fly it and I'm growing tired of the sand, spray, overcoat routine.

I discovered that some NC plastics don't seem to "hold" primer or paints well, when I was finishing the Pinnacle 3" NC I bought from GLR for my 3" FrenzyXL clone. I had done a nice job of filling and priming the NC, then it was necessary to tape off the parting seam to do a little additional work and the primer which had been on for over two weeks just peeled away when I removed the tape. Duplicolor primer is a great primer and the nose cone had been washed, wiped with alcohol and acetone, scuffed and primed. Usually that prep gives good results, the addition of the adhesion promoter the second time around really made a difference.

Did I mention that the 3" Pinnacle NC is a 5:1 ogive and it just looks sexy on long pointy split fin rockets?
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#10
I've had really good results using the urethane Gorilla Glue, some BB's and a dash of water to put nose weight in plastic cones, including the problematic polypropylene type. No skewers needed. Added 400gm of mass to my Madcow BOMARC that way and it's rock solid. For painting I do the solvent cleaning and then sand well with #100 grit, and use KlassKote 2-part epoxy primer. No peeling problems anymore (BTW you definitely want to primer first and then use spot putty as needed, the spot putty WILL crack off if applied to the bare plastic).
Dave Cook 
NAR 21953 L2    TRA 1108
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