Adding nose cone weight

[kat3595]

My son is building his first scratch built design. After checking Rock Sim it appears adding some weight to the nose cone might be a good idea. The Rocket is marginally stable as is but we are not 100% sure of all of the compnent weights we used. My question is what is the best way to add weight to the nose cone. It is a PML 4" standard nose cone. I thought maybe some lead shot from shotgun shells or melting some lead from sinkers and then pouring epoxy over top. If he does this will he have to worry about the epoxy coming loose in the nose cone from the thrust.

Thanks for any help

Ray & Adam Crane

 

[Austin]

KAT,

The best way I have found for nosecones of that size is to pour epoxy in the hole, then pour some 6 shot and kinda gently swoosh it around...the lead shot will sink to the tip and be coated with epoxy. I will usually put another layer of epoxy over it as a cap. Note that the epoxy gets very hot when it starts kicking, so I keep the nosecone in a sink full of cold water and ice until the epoxy sets. That way the cone will not deform from the heat.

Melted lead works well on chilled fiberglass nosecones using the sink and ice, but pouring melted lead in a plastic nosecone would not be recommended. To date, I have a 4" plastic nosecone with about 2lbs of lead in it and it hasn't come loose yet. I have even launched the rocket on an I211 with some serious "off the pad" velocity, and the lead hasn't budged!

Good luck,

Carl

 

[Lee Reep]

If you are like me, you never want to throw away a piece of hardware -- that spare nut or bolt, weird screw with the stripped head, etc. When you finally realize you've been saving them for X years (X being that time unit which says it may be time to go), then use them for nose cone weights...

 

[EMRR]

I've added nose weight in a couple of ways to my 5.5" Upscale of a Nordic Meanie.

The first time, I wanted to be able to change it depending on the motor configuration so I drilled a 1" hole in the bottom of the nose cone and then cut a 1" body tube to the length of the nose cone (on the inside). I then added the weight to the top part of the tube that was inserted into the nose cone and secured it with a screw and washer.

A picture can be seen here

After the terrible crash, I took a different approach for two reasons. 1) Adjustable nose weight it a neat idea but so far for me has never been practical, and 2) I needed much more weight on the 2nd round due to the motor and fin configuration.

The second time around I pushed nearly 16 ounces of clay into the nose cone tip. I hasn't moved in 4 flights nor do I expect it to. I got the clay from Ben Franklins in green. It doesn't dry out.

Nick

 

[kat3595]

Thanks for all of the ideas. One other question. Do I have to worry about too much weight as long as I add weight within reason.

Thanks again

Ray & Adam Crane

P.S. here is a picture of Adam with his rocket

 

[Austin]

KAT,

A good rule of thumb is to add enough weight to compensate for the LARGEST motor you plan on flying. A litle extra won't make much difference.

Cya,

Carl
BTW: NICE glassing job!!!

 

[EMRR]

The Rocket is marginally stable as is but we are not 100% sure of all of the compnent weights we used.

Oh, let me suggest the following:

Build up your model then make two measurements to compare with your RockSim model BEFORE adding nose weight in the RockSim design (just bare components).

With your rocket finished, including the parachute in place, but without the motor:

Weigh it. (I used a food scale from 0-5lbs in .1 oz increments)

After you weight it, then measure the Center of Gravity (I balance mine and then measure from the nose cone).

With these two actual measurement I then create a MASS OBJECT in RockSim, set it and place it so that the RockSim matches the finished rocket. This is a quick and dirty way for addressing material weight, building, glue, paint differences.

THEN, load the biggest motor that you will fly in RockSim and check the stability. If off, THEN add nose weight. That amount is what you want to add to the actual rocket.

- Nick

 

[rstaff3]

Originally posted by kat3595
...what is the best way to add weight to the nose cone. It is a PML 4" standard nose cone. I thought maybe some lead shot from shotgun shells or melting some lead from sinkers and then pouring epoxy over top....

I have used all of the methods discussed...weights covered with epoxy, clay, a removable tube to allow weight adjustment, and haven't had a problem with any of them. Lead shot has the advantage of letting you precisely set the weight. However, I've never used it. Fishing weights, scrap nuts and bolts, even small rocks work fine when covered with epoxy (you have to improvise at midnight). As long as you have the space, mass is mass.

If you have a concern over the weight coming loose, 2 part foam works great. You can get it from Giant Leap, PML and probably most boating supply stores. Just follow the directions and make sure you pour small batches to eliminate overpressurization and heating problems.

 

[kat3595]

AH thanks for not making fun of me. when i posted the picture i clicked on the wrong file. the picture posted obviously did not have Adam in it. hopefully it will this time.

BTW thanks for all of the ideas.

 

[gothique_97]

I think it should be pointed out that if you pour in lead shot and epoxy into the plastic nose cone that you should scuff up the plastic on the inside of the cone so the epoxy will better "grip" the plastic.

*plink plink*

 

[EMRR]

I have also heard that some epoxy gets very hot and people have had to put their nose cone in ice water to prevent it from melting. I have never experienced that, but a workmate has.

Nick

 

[rstaff3]

I finally downloaded the pic...looking nice! Being that its a fairly long rocket, I'm a little suprised that nose weight would be required. Shouldn't require much????

 

[Paul]

From the looks of the pic it shoudnt require nething, but looks can be decieving.

 

[rstaff3]

I hear ya, I wasn't implying he was wrong. At a quick glance it looked like the fins were about the size of my Big Brute's fins. It is stable on small motors with no nose weight, and it's pretty short. But, my eyeballs are no match for RockSim in this regards. Hmmm, he could mail it to me and let me decide for myself

 

[kat3595]

rstaff3

What size motor do you think he would need to use to get the rocket from NW Ohio to Maryland. If you send the motor he might consider the flight.

He He

 

[rstaff3]

touche'

 

[kat3595]

Thought I would post a picture of the finished rocket. First time we have gone to this much for finish but we are pleased. Now if we can only fly it somewhere.

 

[KenParker]

That's one of the best looking upscale Arreaux's I've ever seen.

You're info says you are in NW Ohio. Contact Carl Tulanko here on the forun, and if you are willing to travel a little bit, he can give you directions to one of the sites that he launches at in Ohio.

 

[kat3595]

Thank you. He is pretty proud of it. I am familiar with the Quark launches in Cincinnati.We hope to make it down to one of the launches this summer. However Adam plays legion baseball and averages 6 games a week throughout the summer so it may be the fall before we get a chance to fly it.

 

[rstaff3]

Your rocket really does look great! Please flollow up with a launch report!

 

[gothique_97]

Originally posted by KenParker
That's one of the best looking upscale Arreaux's I've ever seen.

Don't tell Dave Morey!

 

[kgholloway]

Ray,

For someplace to fly your new Arreaux check out

www.skybusters.org

The Tri-City Sky Busters are a NAR section, #535, who fly on fields between Cleveland and Toledo. They usually have two launches a month and I believe that their next launch will be in Amherst.

They are a really nice bunch of guys.

Ken Holloway, Vice President, Blastoff Rocket Club of Erie (NAR #543)