BBertha thread

current project is a two stage big Bertha. though it would be a fast build...well it isn't. started with some left over bits from a baby b, needed a bt an engine hook and centering rings. ordered those and away I built. then ordered a Big Bertha for the sustainer, that is when the 'fun' began. the included c-rings were under sized (outer diameter), replaced those. check the fit of the nose, surprise it has an oversize dia. shoulder(note my previous bertha nose is also oversize in the shoulder), got that sanded down. replaced the launch lug w/ a 3/16" lug. am now debating color scheme. what do you all think of red & yellow? other idea would be white and red. thanks
Rex

Can't wait to hear how she flies! How about some build photos?

well I figured that most everyone has built a bertha...I did however take a few shots. here are a couple of the booster. I did have to make a couple of changes from the stock B Bertha, the aft centering ring got moved forward 1/4"( and the mmt got moved forward 1/8") to allow for the interstage coupler, and the launch lug location got moved (because there was a booster fin in the way).
Rex

started doing decals, and found that the art department has struck again. if one puts the launch lug as per the instructions...then trying to get the aft ring(decal) to match the face card isn't possible. to the art dept. a hand of applause, (CL-) (CL-)*
*sound of one hand clapping
Rex

for the most part this build is done. waiting for the glue to dry on the motor mount, shortly after the tape was removed, and decals applied.
Rex

How much would it take to get you to fly it in that first configuration

Nytrunner said:

How much would it take to get you to fly it in that first configuration

Click to expand...

To the theme music of Ferris Bueller.... "OOOOOhhhhh Yeeeeeeaaaahhhhh...."

it got its' maiden flight today on a pair of B6 motors, about as close to a textbook flight as one could wish for. by the time we glanced at the booster it had already landed (staging at 30' will do that ), sustainer reached about 300'. glamor photo of it on the pad.
Rex

Awesome! Makes me want to build another Big Bertha and add a booster myself! I already need to build another Baby Bertha after a C6-3 CATO last month.

I will note that the 'B' isn't flyable w/o the Big so if you want both you will need 2 babies also note dry weight came out to 135g...definitely not a blink and you'll miss it type launch .
Rex

Good show!

Little Bertha (BT-20) and Micro Bertha (BT-5). RocketMuse put in an Apogee order into which I added a nosecone - once that arrives, I'll start on a BT-50 based Mini Bertha.

looking good. though the Estes mini brute version was bt20 (w/ mini engine power) based. just for giggles I tried doing up a three stage version in OR...it works in theory, methinks that I shall let someone else try building and flying it .
Rex
note this version uses a D12-0 for the 1st stage.

I found the Estes Mini Bertha instructions on JimZ's site. The only difference between those and what I did seems to be the engine hook (I omitted) and the fin material (I used leftover cardstock from the UFO Invader scratchbuild). I decided that, in keeping with the Max tradition, I would reserve "Mini" for the BT-50 based version for which I am awaiting the nosecone.

Of course now this means I have to do a BT-20 based 'Little Max'!

A 3-stage Bertha would be a prime candidate for the Jolly Logic Chute release or a cord-cutter. I use double streamers on Double-D Bertha and fly it on a pair of D12s (or C11s if the wind is up)

Rex R said:

looking good. though the Estes mini brute version was bt20 (w/ mini engine power) based. just for giggles I tried doing up a three stage version in OR...it works in theory, methinks that I shall let someone else try building and flying it .
Rex
note this version uses a D12-0 for the 1st stage.

Click to expand...