Best way to add removable mass to nosecone?

[Chad]

I'm building a 3" rocket for AIRFest this year and have designed it to fly on a G all the way to a K. For the K motor, in order to get decent stability I need to add 3oz of mass to the top of the nose cone. The nosecone is a standard issue LOC 3" plastic nosecone and houses my electronics. I don't have any issue mounting mass since my ebay is in there and i can 3dprint whatever structures I need. My question is what material is typically used to add mass? I don't want to make like a kinetic warhead so something that can absorb energy in a crash would be ideal IMO. I was thinking of something like a water balloon but i have my doubts.

what material have you guys used to add mass to a nose cone?

PS i built a really neat removable/reusable motor mount where i can swap out a 29mm mount used for the G and then swap in a 38mm motor mount for everything else (H, I, J, and K). Once i get at least a checkout flight in i'll do a thread about the build in general.

 

[tfish]

I use lead..as far forward as I can.. 3oz of lead or 3 oz of flour in the nose cone is going to make the kinetic energy of the nose cone the same. Rick has been using water that get dumped at apogee..

Tony

 

[T-Rex]

I normally epoxy BB's in the nose, held in by bamboo skewers or small dowels inserted through the nose.

Maybe you could mount a nut and a tube in a similar fashion, then use a bolt with blue Locktite as the removable weight. Just be sure to pack the threads of the nut with petroleum jelly when pouring the epoxy. (Can you print around an encapsulate nut to make a fixture?)

Water balloon around your electronics just seems like a bad idea to me, but then I tend to be a bit on the paranoid side.

 

[Banzai88]

MAC nose cone bay and never look back.

 

[kuririn]

Bolt, wing nut, fender washers.

 

[LGM-25C]

Lead

 

[lakeroadster]

I make my own nose cones out of redwood. Drill a hole and then use some wood glue and a threaded rod. Thread it in.... thread it out.

 

[Art Upton]

I use lead..as far forward as I can.. 3oz of lead or 3 oz of flour in the nose cone is going to make the kinetic energy of the nose cone the same. Rick has been using water that get dumped at apogee..

Tony

Hi Tony, I had the ACE nose cones that had that bleach bottle opening at the base to put water in. I sold plenty of them about 15 years ago that I had acquired.

But I never read about how anyone dumped the water out of those at apogee; can you explain that?

 

[Art Upton]

I normally epoxy BB's in the nose, held in by bamboo skewers or small dowels inserted through the nose.

Maybe you could mount a nut and a tube in a similar fashion, then use a bolt with blue Locktite as the removable weight. Just be sure to pack the threads of the nut with petroleum jelly when pouring the epoxy. (Can you print around an encapsulate nut to make a fixture?)

Water balloon around your electronics just seems like a bad idea to me, but then I tend to be a bit on the paranoid side.

A guy in Michigan had a semi jet like looking 7" rocket cato at Three Oaks. The Cato happened where all the Epoxy BBs exploded and showered close in cars behind the flight line leading to lots of damages. He agreed to paid all their deductibles.

Think of just one person not agreeing to a deducible payment what that would have cost in the long run.

If it was flower nose weight , well it would have been nothing.

 

[tfish]

Hi Tony, I had the ACE nose cones that had that bleach bottle opening at the base to put water in. I sold plenty of them about 15 years ago that I had acquired.

But I never read about how anyone dumped the water out of those at apogee; can you explain that?

I've not seen or done this..
Rick Maschek out at FAR....has..used water as ballast in nose cone..sounds like at apogee..nose over..the tip of the nose comes off/loose..which allows the water to dump out.

Tony

 

[teepot]

I have used quick links and nuts for adjustable nose weight. A 1/4" QL and a couple of 1/2" or 3/4 " nuts will give you 3 ounces easy.

 

[BigMacDaddy]

I've not seen or done this..
Rick Maschek out at FAR....has..used water as ballast in nose cone..sounds like at apogee..nose over..the tip of the nose comes off/loose..which allows the water to dump out.

Tony

Wonder if you could do the same thing with sand... I'd worry about water leaking into my rocket...

 

[cls]

Hi Tony, I had the ACE nose cones that had that bleach bottle opening at the base to put water in. I sold plenty of them about 15 years ago that I had acquired.

But I never read about how anyone dumped the water out of those at apogee; can you explain that?

Dick Hagen used to do that with his M powered "Ba Da Boom!" rocket. He'd put in colored water for a really pretty rainbow at 18k ft at Black Rock. Now I'm slapping my forehead because I never thought to ask Dick how he got the water carrier opened up at the right time. Hope Tony remembers...

(edit, gosh we all miss Dick.)

 

[cls]

what material have you guys used to add mass to a nose cone?

for non adjustable ballast:

I like the instructions on the LOC 7.5" V2: push a couple finishing nails at 90 degrees through a few inches back from the front of the nose cone, trim them off and file them flush. Add rocket caviar, which is epoxy slurry with BBs, lead shot, or anything cheap. I found 1/4" steel washers were the least $/pound and heaviest thing.

let the epoxy cure nose down in a bucket of water to dissipate the extra heat, deep epoxy will get hot. shallow and wide, no.

If you really are going to fly this machine on different motors, consider getting another or 2 3" noses with none or different ballast.

 

[tfish]

Dick Hagen used to do that with his M powered "Ba Da Boom!" rocket. He'd put in colored water for a really pretty rainbow at 18k ft at Black Rock. Now I'm slapping my forehead because I never thought to ask Dick how he got the water carrier opened up at the right time. Hope Tony remembers...

(edit, gosh we all miss Dick.)

I was thinking about him and that rocket..Seth has it and it's... IIRC... 3 gallons of water and a water proof charge. Seth and I have talked about doing a flight.

Tony

 

[Rob Campbell]

Why not two identical nose cones. One with ballast and the other without. Easy to exchange and no worries about stuff coming loose.

 

[Chad]

Why not two identical nose cones. One with ballast and the other without. Easy to exchange and no worries about stuff coming loose.

i was thinking about that too. I want to run some more simulations, the overall goal is to fly this one airframe on G-M. I only have budget and time to do G-K at AirFEST this year and so am stopping at K for now. I think the same 3oz will be stable on the L and M I have in mind but haven't looked at it closely, if it is then maybe two nosecones makes the most sense.

two 9volt batteries are about 3oz so i can just strap two together and mount it on the ebay as far up the nosecone as they'll go. That would be easy. I was just thinking that in teh event of a crash it would be nice to have the extra mass shatter or splash or do something else to absorb energy vs transferring it all to what the nosecone hits.

 

[Donnager]

I have used quick links and nuts for adjustable nose weight. A 1/4" QL and a couple of 1/2" or 3/4 " nuts will give you 3 ounces easy.

Agreed.

I either use skewers, small dowels, screws, or wire threaded through the nose. If I'm doing HED deploy, I thread the recovery cord for the nose over the wire that retains the lead shot, and cast it into the weight, keeping the mass as far forward as possible, and just leave the loop attached to the empty nose.

A tablespoonful of BB's with some epoxy or urethane glue will probably get you three oz. as well.

I probably wouldn't bother with a second nose.

 

[jqavins]

A guy in Michigan had a semi jet like looking 7" rocket cato at Three Oaks. The Cato happened where all the Epoxy BBs exploded and showered close in cars behind the flight line leading to lots of damages. He agreed to paid all their deductibles.

Cripes, y'don't use loose BBs. Y'use BBs mixed in with epoxy.

Wonder if you could do the same thing with sand... I'd worry about water leaking into my rocket...

I'd be concerned about dumping sand, or any other solid like that.

 

[SolarYellow]

I was just thinking that in teh event of a crash it would be nice to have the extra mass shatter or splash or do something else to absorb energy vs transferring it all to what the nosecone hits.

Good thinking. It’s well understood that the many small pellets in a bird shot shell each act individually when encountering a penetrable material. Even if they hit it in a wad, the penetration tracks are made by each pellet individually, for the most part.

I could see using construction line chalk, AKA tracking powder.

Or if you wanted something more consolidated, BBs in expanding foam rather than epoxy. #9 bird shot is really tiny, but costs more per ounce than BBs.

 

[86mustang408w]

My Big Daddy nosecone with a bulkhead, eyelet, and exposed to cover the bulkhead from ejection blasts is about perfect. You can add modeling clay, or lead weight. You could melt it, and form it to the same of the nosecone, and epoxy it in. I've seen guys epoxy 50 cal musket balls to ths inside of the nosecone one at a time to get the desired weight, to fishing sinkers too. Its a 3" cone, with a 2.5" bulkhead. I just dropped it in place. Used some CA to tack it, then dumped epoxy in it to help with the ejection blasts...Many options. I could weigh it if need be..lmk...

 

[Art Upton]

Does anyone remember when the NAR official contest payload weight went from being a Lead slug [some place I should still have one] to a paper tube holding loose sand?

 

[cls]

Yeah, something about lead being toxic... ?

Remember when Vern said balsa nose cones were safer than (denser) plastic because of lower ballistic coefficient? Yeah, right.

 

[Art Upton]

Actually being hit by a nose cone a good friend of mine many years my senior in about late 1970s, would rather have been hit by a balsa cone, they disinagrate and plastic does not. Good thing the campus we were flying on was in the back 40 of the Medical Collage of Ohio and he got good care.

Edit: after that incident I found out we lost all flying privilege's there; I was just glad he was OK afterwards

 

[Sooner Boomer]

Are you still looking for a way to add mass? I've got some very dense powdered metal. You could either mix it with epoxy, or make a frangable container for it. I can bring it to you at Airfest.

 

[Chad]

Are you still looking for a way to add mass? I've got some very dense powdered metal. You could either mix it with epoxy, or make a frangable container for it. I can bring it to you at Airfest.

Once I got everything together the stabilization actually worked out so I don’t need additional mass. I have this removable bulkhead I made, that I’ll show you, and it (and recovery gear) shifted the CG far enough ahead that I don’t need the extra mass.

I’m hoping for 4-5 flights on Sunday on the same airframe which will be, by far, the most flights I’ve ever done in one day. Planning a G, H, I, J, and possibly a K flight.

 

[Sooner Boomer]

I’m hoping for 4-5 flights on Sunday on the same airframe which will be, by far, the most flights I’ve ever done in one day. Planning a G, H, I, J, and possibly a K flight.

Woo Hoo! The most flights I've ever gotten at a launch was three. Not at Airfest. Not even at Argonia. Looking forward to seeing your stuff!

 

[High Desert Rocketry]

I've not seen or done this..
Rick Maschek out at FAR....has..used water as ballast in nose cone..sounds like at apogee..nose over..the tip of the nose comes off/loose..which allows the water to dump out.

Tony

 

[Gunstar]

I designed this to have adjustable weight with a BT-80 nose cone
https://www.printables.com/model/275392-model-rocket-adjustable-weight-nut

 

[High Desert Rocketry]

Many, many years ago (1990s?) at a launch, someone was bragging about having 44 pounds of lead in their nosecone for stability. Just like bowling balls, I thought that would make a nice kinetic energy weapon if deployment failed...got to be something safer. So I worked on safe ballast weight...sand or dirt, which ever is available at the launch site, that gets deployed at apogee. Also thought about water. I now favor water for ballast. Yes, it takes up more room than denser material but is easily deployed at or after apogee.

On rockets with removeable metal tips, install a lanyard to the tip connected to the nosecone bulkhead. When rocket inverts after chute deployment, the tip comes out and safely drains the water. Since you shed that mass, it also allows for a lighter weight chute and less stress on the shock cord and attachment points. Worked so good, I incorporated it into the competition I do at FAR.

https://friendsofamateurrocketry.org/wp-content/uploads/2023/12/FAR-51025-Unlimited-2024.pdf

I was surprised at the first year as an 'option for extra points', that university engineering students had a problem with just the 500 mL requirement on 'How to do it'. And I remember one team being pulled from the competition because their professor thought it dumb putting water in a rocket...guess NASA is too for the thousands of pounds of water delivered to space stations.

Now required each year, I'm amazed at what students design. A bottle with a stopper/cork attached to the chute shock cord that pulls out the stopper, printed nosecones with hinged doors that open on descent allowing the water to drain, etc

Another safety thing I would joke about is if the descent is ballistic, it wets down vegetation surrounding the impact area to aid fire prevention.