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Nose weight question

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Orion14ed

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I am getting ready to fly my 4" Patriot this weekend and have one concern. I epoxied the bb's in with some 30 min epoxy after roughing up the inside of the tube but I did not use a dowel or any other supplementary material for the epoxy to catch to. It currently is just sitting in there with no backing as well. My question is, is there anything I can do at this point to try and secure the weight further? I was debating putting a bulkhead right after the epoxy bb mixture just to have it covered and *hope* that in the case that the weight became dislodged it would do a little to help keep it from completely going through the back end of the rocket. The flight isn't going to be pulling any crazy amount of G's and sims at a max acceleration around 250 ft/s^2. I am aware that due to the way I epoxied it in there is a chance that it comes lose, but is it considerable enough to completely scrub the attempted based solely on that? Would adding the bulkhead help?
 

noffie79

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I certainly don't think the bulkhead will hurt any. Are you planning on a second bulkhead in the shoulder of the NC to attach your harness to?
 

terryg

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I would fill the rest of the nose cone with 2 part foam to keep the weight in place.
 

Igotnothing

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Or, lacking foam, swatch of 6 ounce fiberglass cloth.

I have had the bbs come loose in a polycarb nosecone on a 4" V2 with a G motor. YMMV. Rocket went up maybe 12 feet, danced around on it's tail till the motor was spent, and then crashed.
 

CZ Brat

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In my Poly NCs, in addition to Gorrilla Glue (GG), I drill and insert a 1/2" dowel just below/just touching the weight. I have even used the dowel as an attachment point for the shock cord. I have done this on 5.5" and 4" LOC NCs.

FYI, there are lots of different, yet effective, ways of doing NC weight. I actually make a mold of the inside of the NC and cast my lead weight as one form fitted piece. I then use GG to glue in. Then add the dowel. GG is very sticky (even on Poly), it expands to fill in small gaps, and a little around the edge creates a strong bead that holds everything in place. GG is similar to the polyurethane expanding foam, but more dense. To make it less dense, add a couple drops of water and it will be a foam.
 
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CORZERO

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Has anyone that hasn't reinforced an epoxy/lead shot/BB nose cone weight actually had a slug come loose? I have not. And I don't even scratch the inside of the cone. Aeropoxy 6209.
 

CORZERO

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Or, lacking foam, swatch of 6 ounce fiberglass cloth.

I have had the bbs come loose in a polycarb nosecone on a 4" V2 with a G motor. YMMV. Rocket went up maybe 12 feet, danced around on it's tail till the motor was spent, and then crashed.
Did you pour BB's into the cone and then pour epoxy over them?
 

CORZERO

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The flight isn't going to be pulling any crazy amount of G's and sims at a max acceleration around 250 ft/s^2.
62,500 ft/s? That's roughly Mach 56. I would definitely reinforce the slug.
 

JimJarvis50

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62,500 ft/s? That's roughly Mach 56. I would definitely reinforce the slug.
+1^2

I have a Big Daddy modified for 54mm motors, so I had to add maybe a pound of nose weight. I lined the inside of the cone with roughly 1/8" of thickened epoxy from the BB's in the tip down to the shoulder. That has held in the weight just fine. Just kept turning the cone until the epoxy set up.

Jim
 

Buckeye

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Has anyone that hasn't reinforced an epoxy/lead shot/BB nose cone weight actually had a slug come loose? I have not. And I don't even scratch the inside of the cone. Aeropoxy 6209.
Yes. Minnie Magg. Bob Smith hobby epoxy.
 

CORZERO

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Yes. Minnie Magg. Bob Smith hobby epoxy.

Did you also pour BB's into the cone and then pour epoxy over them? Or are we mixing BB's with epoxy then pouring the concoction?
 

NattyDread

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Read about poly properties and adhesion. You'll want to drill and put in a brass dowel
 

dixontj93060

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Forever_Metal

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Orion,

Are you going to use the same motor primarily, or do you plan on using different impulses (ie. h's then maybe i's, or maybe even bigger?)

One thing I noticed on my Patriot is that the weight needed to get the cg where it should be varies alot with the motor used. My bird on an AT I500 to 3700' only needed 300g, whereas on a AT J, that weight has to at least double to get the cg where it belongs.

If you plan on flying within a small range of motors/impulses/weight, find the highest impulse motor you'll want to fly and use that when you simulate and test for cg and how much weight needs to go into the nose. I have an electronics bay in mine and dual-deploy, it sim'd to 300g of nose weight needed to keep the cg @ 28" with the small impulse I.

Hope your build has been as fun as mine; got to meet many folks and learn some basics from them all!!

fm
 

Orion14ed

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Just a follow up,
while it sure did not pull 58 G's (woops), I flew the rocket and was able to certify. I ended up using foam to hold the weight in place, and was actually lucky I did so since the nose cone came down pretty hard on a road which very well could have dislodged the weight if it was not secured as well as it was by the foam. I shook the nose cone around and the weight is not lose, so it is perfectly fine to fly again, but moving forward I intend on treating the addition of weight more carefully since I really do not want to have a rocket become unstable midflight because of it.

Thanks so much guys! And at least this thread is filled with examples of weight coming lose that I could not find myself, so it should serve as a warning to anyone who does not secure their weight.
 

neil_w

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How much does the amount of weight affect the answer? If I was going to put about 1 oz (pretty small quantity compared to what some are discussing here) of split shot into a plastic NC, to be flown on E motors at most, would that be a small enough application that it should be OK?

Also, it sounds like Gorilla Glue could be a good solution here, but I'm still not clear exactly how to use it. With epoxy, I'd mix the shot into the epoxy and pour the whole mixture in. With Gorilla Glue... same? Add glue to the top after the shot is in? Add it to the bottom and pour the shot into it? If anyone could provide a little more detail on this I'd be interested to hear.
 
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