Little Joe

[BigMacDaddy]

I was trying to use up one of the random larger tubes that I was given and decided to make a Little Joe. However, the 3D printed parts + tube wound up being too heavy so decided to change horses mid-design and make this mostly 3D printed but scaled to a BT-80 tube (around 10cm BT-80 tube makes up top portion of body). Below is my latest design -- I found some 3D designs online but wound up redesigning this from scratch last night since the ones that I found had some odd poly issues. I was inspired by the Fat Boy thread with the 7 engine cluster so went ahead and designed this to take a removable cluster mount that would let me change engine configurations (or to put in a bottom plate in with more accurate details for display).



p.s., Just realized that I accidentally left my fins sticking out too far in my mock-up (they can slide all the way in).

 

[BigMacDaddy]

Latest build updates from last few days...

The larger random tube has the original nose cone I downloaded with some modifications... I think I will go ahead and finish this verison with minimal 3D printed parts (fin base tower details), plywood fins, and a cluster motor mount.

The smaller BT-80 version has my redesigned nosecone and body portion. I decided to go with a single 24mm D engine mount for this version since it seemed light enough. This is a swappable cluster mount that can have a variety of configurations installed (likely with changes in nose weight).

 

[UPscaler]

Wow, this is killer! Great design work.

Braden

 

[BigMacDaddy]

Launched both my Little Joe II rockets today.

BT-80 version went up on a C11-3 (surprisingly fast!) and the 3" version went up on a D12-5 (and I used one of the older Cobra motors I just bought so great that this did not CATO - knock wood!!!!). the 3" version may have windcocked a bit or maybe marginally stability (it has 1.5oz of weight in that nose spike).

BT-80 mostly 3D printed version:



3" recycled tube + minimal 3D printed parts version (parachute did not deploy particularly well but it did not get damaged - nose cone and fin stuck in the mud with a satisfying thunk):

 

[BigMacDaddy]

Wow, this is killer! Great design work.

Braden

Thank you!

 

[BigMacDaddy]

The swappable cluster setup is one of the most interesting aspects to this rocket design. I added a new configuration -- 18mm center + 6x canted mini engines. Now I just need an easy way to swap out nose weight (I have some ideas).

 

[Saluki]

How's the X-15 coming along?

 

[BigMacDaddy]

How's the X-15 coming along?

I made a mistake when assembling (I was in a rush so had not marked the tube when I started so paid the price). I made a bunch of revisions of the design to help make it foolproof so I need to reprint parts. Anyway, got a bit annoyed so gave it a break.

 

[BigMacDaddy]

I think that I may not need to change weight for some configurations... Added 3x and 6x 13mm cluster + 18mm center motor configurations... Printing cluster motor retainer / canister now so will do a swing test...

 

[BigMacDaddy]

This might be my favorite cluster configuration... Swing test says it's stable with 6 mini engines A10s and a C6-5... Don't ask me why I decided to get white filament in the last order...



Of course there is always a next version..