DigBaddy's Big Daddy Nose Weight Mod

[DigBaddy]

This is stolen from similar designs, but may be useful for Big Daddy and other rockets. This is for my 4x24mm BD. It'll allow very fast swapping of nose weight modules (Estes yellow spacer tubes) if I want to fly two or four motors and can have tubes set for certain combos. Four E26s won't need as much weight as four E12s.

Since we need to cut off the shoulder of the nosecone and insert a bulkhead on these, I just used a centering ring.

Then, inserted a length of BT50 and epoxied where it meets the tip of the cone, to the centering ring, and then put a cream container cap thread on the aft end of the tube and bulkhead. These cap threads fit perfectly over BT50.



Make some weighted tubes with shot and epoxy.



Weight tube in first, empty tube as spacer. I need to make one small rear spacer of foam to cinch down under the cap to take out just a bit of gap. Then, put the cap on.

 

[dhbarr]

Just don't put your weight tube in upside down!

 

[Huxter]

Great idea - thanks for posting w pics! I think you'd want the heavier side of the tube at the top of the nose cone.

 

[RocketTree]

What a great idea! I haven’t seen this done before. Might have to try that in a future build.

Looks like that style of threaded cap could also be modified and used for 24mm motor retention.

 

[Pepe Le Pew]

Genius witchcraft!

 

[JimByrne]

I just dropped some lead bullets in the nose with epoxy to hold them in. worked great.

 

[BigMacDaddy]

Cool idea / design!!!

 

[Cape Byron]

Brilliant. Three thumbs up.

 

[Sandy H.]

The thing I like the most is re-using stuff we have in excess. The yellow tubes are either scrap or good for a tube fin after using. This is a great use and modular for other rockets using your design. Re-using a screw-on lid/bottle top is great as well.

Thanks for passing the implementation along. I've seen similar ideas to optimize for different CG requirements with changeable weight systems, but your modular/re-use approach takes it to a higher level.

Well done!

Sandy.

 

[KenECoyote]

THANKS!!!

I had seen this a while back and thought "boy, I've GOT to try this later!", but tbh I've forgotten all about it since I stopped building hp for about 5 years.

Recently I've been pondering how to build a modular type 5.5" rocket where I'm building it for single-deploy, but it can be converted to dual and this would work very well for that.

Thanks for sharing!

 

[KenECoyote]

Just don't put your weight tube in upside down!

Great point!

Dummy Fix: An Up Arrow drawn on the sides with a Sharpie.

 

[BABAR]

Brilliant. Three thumbs up.

I knew Aussies were unique, but…..

Wouldn’t hurt to glue a Kevlar or twine loop inside the weighted tube, with the loop extending out the caudal end when loaded, you can bunch it inside when capped in place, when you want to remove, pull the cap and grab the loop and pull (just in case tube weight gets stuck. More eloquent than banging it in your work bench to get it out.)

 

[DigBaddy]

I knew Aussies were unique, but…..

Wouldn’t hurt to glue a Kevlar or twine loop inside the weighted tube, with the loop extending out the caudal end when loaded, you can bunch it inside when capped in place, when you want to remove, pull the cap and grab the loop and pull (just in case tube weight gets stuck. More eloquent than banging it in your work bench to get it out.)

That's a great idea!

 

[Back_at_it]

I thought I dreamed this up all on my own. It's a little scary as I've come up with almost the exact same solution to my next Big Daddy 29mm build. I knew it was too good to be true

Oh well. Here is how I did it.

Parts list.
- Scrap piece of BT20 tube.
- Scrap center piece of a BT20 centering ring cut down to fit inside the BT20 tube.
- 3" Plywood bulkhead. Found these at Michaels. 10 in a pack for $3. Drilled a 1" hole in the center.
- Backer for the bulkhead to reinforce where the screw eye attaches.
- Screw eye.
- Estes 18mm motor retainer.
- 18mm motor block (not shown).



Inserted the scrap center piece into the tube to keep the weights from falling out the nose. Inserted an 18mm thrust ring to keep it in place.



Screw eye and backer attached to bulkhead.



Inserted the bulkhead into the nose cone just above the shoulder then slid the BT20 tube into the hole until it bottomed out against the tip of the cone.



Attached the threaded section of the motor retainer.



Screwed on the motor retainer cap



Filled two removable tubes with BB's for nose weight.