Solidarity Ribbon Bertha Plywood Builders Kit

Description

Big Bertha, Super Big Bertha, Baby Bertha — some of the favorite Estes releases of all time. Inspired by these classics, I innovated using a combination of 3D printing and CNC milling to help people remember and honor causes that are important to them with brightly colored silky nose cones and ribbon fin inserts for included plywood fins. October is Breast Cancer Awareness Month! I am producing both Super Baby Bertha version w/ four single-piece 2mm plywood fins (no need to assemble fins from multiple parts!) and 24mm motor mounts (saves $$$ on every launch!) as well as a Big Bertha version with improved plywood fins and upgraded power in the form of a 24mm motor mount (go higher, faster, and louder!).

The BT-80 Super Baby kit includes the colored (Silky Pink for Breast Cancer Awareness) nose cone and a pair of colored ribbon inserts for opposite fins. In addition, it includes four 2mm plywood Super Bertha-style/sized fins (two with ribbon cutouts), two 2mm plywood BT-80 to BT-50 centering rings (one slotted to mount around fins and other intended to sit against bottom of fins), a 3D printed stuffer tube centering ring / block, and an quarter-turn engine retainer cap / mount and BT-80 centering ring / engine block for the BT-50 stuffer tube.

The BT-60 Big kit includes the colored (Silky Pink for Breast Cancer Awareness) nose cone and a pair of colored ribbon inserts for opposite fins. In addition, it includes four 1.75mm plywood Bertha-style/sized fins (two with ribbon cutouts), two 2mm plywood BT-60 to BT-50 centering rings (one slotted to mount around fins and other intended to sit against bottom of fins), a 3D printed stuffer tube centering ring / block, and a quarter-turn engine retainer cap / mount and BT-60 centering ring / engine block for the BT-50 stuffer tube.

These kits help you fill some gaps in the lineup by making a BT-80 based Super Baby Bertha model (you provide a full-length Estes BT-80 tube, BT-50 stuffer tube, and recover system) or an up-powered BT-60 based Big Bertha model (you provide a full-length BT-60 tube and short motor mount tube or stuffer tube if desired). Both models are much more impressive than the original BB and have awesome flights on 24mm D and E engines. You could also adapt the Super Kit to make a Super Big Bertha by adding a BT-80 coupler and a 2nd BT-80 tube. However, I have not tested how that longer / heavier rocket will launch on 24mm engines if you want to use the included engine mount parts.

Here is a Super Baby Bertha I built using the same parts (minus the pink nose cone and ribbon inserts) launching on a D12-5:

And here is the same model launching on an E12-6:

Here is the OpenRocket simulation (you will receive the ORK file with your order so you can update with your specific build). Note: The Bertha models are extremely stable (I used the base drag hack to take into account the stability of this short-stubby rocket).

Note: 3D printed and CNC’d parts may require some cleanup, support / tab removal, filling, sanding, etc… Nose cones have a seam / vertical line on one side. Silky printed parts can be sanded but will lose some luster. You can wipe these parts down after sanding with acetone on a paper towel to gain much of the luster back but it is not quite what it was when originally printed.

Disclaimer: I only list and sell rockets that I have built and launched stable. However, so much of the build for these models depends on choices you make in assembly, motor configurations, weight of fillets / glue, etc… Thus, I cannot guarantee that your flight will be as stable as mine. I strongly recommend that you update Open Rocket simulations files to match your build and do a swing test or other stability test to confirm stability prior to launching. Also you should always pay careful attention with “heads up” launches till you are sure of the stability of a new model rocket. Please follow NAR guidelines as well as local and other laws and regulations.