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(BAR-46) The Lucky 7

I got this design from a fellow rocketeer over at TRF, whose member name is Babar. Here's a link to his original design... 2FNC--- 2 linear fins and a nose cone. The Lucky 7

I thought I'd take a crack at making one of these that'll fly on 24mm motors. It's got a place for my Altimeter Two and will handle any Estes or Aerotech 24mm motors. Some dowels were added on both sides of the fin, and it also has doubled up body tubes, just to ensure longevity. I'll use some 2 ply's of 1/16" thick Basswood to make those 1/8" Basswood fins.

The plan is to start with the D12-7 BP motor... and work my way up to the Aerotech F32T-8.

2025-04-24

Got to spend a little quality time out in the barn this afternoon. Turned the Nose Cone and Transition on my wood lathe.

2025-04-25

Body Tubes, Mock-Up, Lag Screw Eye, and Gluing Begins

2025-04-25

Adding the fin dowels and building the triple tube BT-52H

There are 3 pieces of BT-52H in the triple wall fin can. The outer is an intact tube, the two inner tubes were cut twice longitudinally to the correct O.D. and then they were glued and inserted into the outer tube.

2024-04-27

Cut the BT-3 Launch Lugs, Sanded the Fin Dowel, punched vent holes in the tubes and sanded the Motor Tube. Glued the Fin Can Launch Lug.

Gluing the BT/C-50 to the Transition, and attaching the Upper Fin.

By printed the "Back View" of the OpenRocket model, a couple of temporary cardboard angle templates were made. Those were taped to the Lower Fin. That'll hold the fin in place, at the correct angle, while tacking the Upper Fin to the Lower Fin with wood glue.

2025-04-28

Gluing the Upper Fin, Motor Ejection Tube and Final Assembly

The temporary cardboard supports were removed this morning and the Fin Dowel was inserted into a bed of Wood Glue. Glue fillets to follow.

The Ejection Tube, a piece of BT-50H, was placed on the mandrel of my wood lathe and the white paper layer was removed. This makes for slip fit into the fin can. I don't really want any friction at this joint, the motor needs to eject and the lanyard straps of Kevlar will yank this tube and the laundry from the rocket... or at least that's the plan anyway.

I'm contemplating doing a static test of the recovery system...

Also finishing up gluing all the pieces together...

CAD

Created the model and started on the drawing package.

2025-04-29

Revised the Ejection Tube... actual parts and new drawing set. Gluing on the Upper Launch Lug.

2025-05-01 Swing Test

Just when you've got this whole rocketry thing figured out... you realize you don't. I swing tested the rocket today and it was not stable. No matter the orientation, it just wouldn't fly nose first reliably.

So the nose cone was bored for a 3/8" dia piece of ballast x 1.1" long, 15 grams.

That did the trick. Sim shows the rocket is now at 1.6 caliber or 10.6%. I think it was the % that bit this rocket, which I usually shoot for 8% to 12%... which it was under this time without ballast.

I tested the rocket in (3) orientations, all were stable, (1) is posted up here.