Super Baby Bertha from a Super Big Bertha?

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BRS Hobbies

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Anyone make a Super Baby Bertha (BT80 size) from an Estes Super Big Bertha? I was wondering if it's possible, with enough room to pack the parachute and how much (if any) nose weight is needed.
 
A Super Baby Bertha would be approximately 19” long so I’d say there’s plenty of room. Nose weight is a bit different since short fat rockets don’t always follow the same stability rules. Next time I have Open Rocket running on my laptop I’ll try a quick sim and check it out.
 
hmm my 'boe' gives me a body tube length of approximately 12.6"
Rex
 
hmm my 'boe' gives me a body tube length of approximately 12.6"
Rex
I was guesstimating based on overall length - Big Bertha 24”, Baby Bertha 12 3/4” - not the body tube. The overall length of my Mega Mosquito is a little over 18 1/2” and I don’t recall adding nose weight.
 
Am I correct that the Baby Bertha uses the same size fins as the Big Bertha? If that's the case, then the upscale would be really easy with only needing to shorten the main tube and the stuffer tube.
 
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Hey you could be starting a whole new trend here. First the Baby Super Bertha followed by all the Super Goony Rockets.

Nike Goony.jpg

-Bob
 
I was guesstimating based on overall length - Big Bertha 24”, Baby Bertha 12 3/4” - not the body tube. The overall length of my Mega Mosquito is a little over 18 1/2” and I don’t recall adding nose weight.

Played around on Open Rocket with the Super Big Bertha into a Super Baby Bertha - shortening it an OAL of 22.75” it stays above .85 caliber of stability with no added weight with an H70-10W. Adding 2 oz of nose weight keeps it well over 1.5 caliber.

An Estes D12 gives you a decent low altitude flight, an E12-4 gives you a really nice 500-ish foot flight while the big 29mm BP motors have a little slower than optimal but safe liftoffs with apogees 650-1065 feet. Going to bigger composite motors goes well over 2000 feet to 3100 feet.

Seems like a no-brainer to me for Estes to release a Super Baby Bertha. I’m really tempted to buy another SBB and build one - plus a booster from the leftovers!
 
baby bertha fins are a tad smaller than the current big bertha fins, not sure how the baby fins compare with the original Ranger/Big Bertha fins, those might turn out to be the same size. i can say that baby fins are 1/32" thinner (3/32 vs 1/8").
Rex
 
Hey wouldn't it be cool if we could have some sort of Baby Super Bertha or Gooney contest. A start date, and end date and some sort of basic guidelines. Maybe Estes could donate the prize of another Super Big Bertha. WInner would be picked from a poll on this site.

-Bob
 
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