Big Bertha upscale questions

[qquake2k]

I was thinking about doing a Big Bertha upscale, based on a 3" body tube. Problem is, I can't find a suitable nose cone anywhere. I might be able to turn one from a balsa block (I have a woodlathe), but would it be too heavy? Would I need to hollow it out some?

Jim

 

[tbzep]

I was thinking about doing a Big Bertha upscale, based on a 3" body tube. Problem is, I can't find a suitable nose cone anywhere. I might be able to turn one from a balsa block (I have a woodlathe), but would it be too heavy? Would I need to hollow it out some?

Jim

It won't be too heavy as long as you don't mind using composite motors or clustered BP motors. The Estes Super Big Bertha/Broadsword was BT-80 based (2.6") and flew decently on a D12-3, but not all that high. Three inch tubing is heavier so even a light weight nosecone would likely be a little too heavy for a single D12-3.

 

[qquake2k]

It won't be too heavy as long as you don't mind using composite motors or clustered BP motors. The Estes Super Big Bertha/Broadsword was BT-80 based (2.6") and flew decently on a D12-3, but not all that high. Three inch tubing is heavier so even a light weight nosecone would likely be a little too heavy for a single D12-3.

I was planning on making it with either a single 29mm motor mount, or a 3x24mm cluster.

 

[rokitflite]

I was planning on making it with either a single 29mm motor mount, or a 3x24mm cluster.

You are fine then

 

[tbzep]

You are fine then

Yep. If you don't overbuild, you could fly it on a single E30 or maybe E15 for small fields.

Three D12's will give you a small 51 N/s F. Three E9's will give you an 85 N/s baby G.

 

[sandman]

I was thinking about doing a Big Bertha upscale, based on a 3" body tube. Problem is, I can't find a suitable nose cone anywhere. I might be able to turn one from a balsa block (I have a woodlathe), but would it be too heavy? Would I need to hollow it out some?

Jim

Why not use a more common size like a BT-80 tube or a BT-80H (heavy duty version) where you can get common parts readily like nose cones (me SEMROC, turn your own, etc.) but more importantly things like centering rings tube couplers and motor mounts.

Balsa wouldn't bee too heavey and they are easily drilled out to make them lighter or even to have room for nose weight. Although on an upscaled Big Bertha you wouldn't need to add weight.

How about an upscale Astron Ranger?

Just a suggestion.

 

[qquake2k]

I think I found a nose cone. Balsa Machining Service has a BNC300BB listed. There's no photo of it, but there is a photo of the BNC80BB which looks like the right one.

https://www.balsamachining.com/newCONES.htm

 

[qquake2k]

Why not use a more common size like a BT-80 tube or a BT-80H (heavy duty version) where you can get common parts readily like nose cones (me SEMROC, turn your own, etc.) but more importantly things like centering rings tube couplers and motor mounts.

Balsa wouldn't bee too heavey and they are easily drilled out to make them lighter or even to have room for nose weight. Although on an upscaled Big Bertha you wouldn't need to add weight.

How about an upscale Astron Ranger?

Just a suggestion.

Well, an upscale BB based on BT-80 would be about 39" tall. Based on 3", it would be about 45" tall. I wanted to go a little bigger than the Super BB, and fly it on either a single 29mm or 3x24mm cluster.