2 stage bertha anyone?

was trying my hand at using OR to designing a multi stage rocket...this is what I came up with. all I ask is that if someone builds it, please post pictures.
Rex



View attachment rexga.ork

I thought of something similar with a Baby Bertha with a C6-5 and C11-0 motor combination. OR said it was a good combination.

I have always wanted to do this as well. The swept-back fins leave a space where "filler fins" could be added to make a pretty formidable booster.

You may see me trying this at some point. The Bertha is a great rocket, but doesn't go to high. It would be cool to really get'r up there!

EDIT: Here's my take on it:
View attachment 2-stage Bertha.rkt

We've got a club member that has a fairy awesome two stage Big Bertha that takes three Estes E9 BP motors in each stage.

Rex R said:

was trying my hand at using OR to designing a multi stage rocket...this is what I came up with.

Click to expand...

I like what you came up with there.

I've often thought of just plugging a Baby Bertha into the back of a Big Bertha - time to execute!

essentially that is what this is . Chad; knowing how you like computers...the baby bertha component has a body tube of 5" and the fins are mounted 7/8" forward of the aft end(so it will tumble recover). motor retention for both stages is the stock engine hook(sustainer hook gets trimmed to the bare essentials, while the booster can be left alone). I see that I used a semroc cone, my bad, if you want to use the(Estes) bertha nose the rocket will be a half inch shorter.
rex

Rex R said:

was trying my hand at using OR to designing a multi stage rocket...this is what I came up with. all I ask is that if someone builds it, please post pictures.
Rex

Click to expand...

I love the Berthas,I have Big Bertha with 24mm -- maybe I could build booster with E-12. Dang-it Rex R .

got another one.
rex

I've CHAD staged D12-0's to balsa nosed Berthas. They have plenty of weight in the front and lots of fin in the back making them good candidates for CHAD staging. I haven't tried E12-0 but I'm going to

Progress so far: Two stage air frame with (2) 24mm x 95mm (just in case) motor mounts, 8 papered 1/8" balsa fins - curse you Rex!

um, 24mm(why am I not surprised). hopefully you haven't attached the booster fins yet. the larger fins & motor call for a change in fin position on the booster, 1" forward of the aft end of the tube, if you want the booster to tumble.
rex

I uploaded this from the internet a few years ago, maybe some on will recognize it.

Rex R said:

um, 24mm(why am I not surprised). hopefully you haven't attached the booster fins yet. the larger fins & motor call for a change in fin position on the booster, 1" forward of the aft end of the tube, if you want the booster to tumble.
rex

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Just because the mounts are, doesn't mean they'll ever be filled - just in case. Fins located one inch forward is an issue now, I seem to not have enough tube to make that happen - or maybe I have too much fin.

RocketflierVB said:

I uploaded this from the internet a few years ago, maybe some on will recognize it.

View attachment 130550

Click to expand...

I've never seen it, but I like it! I was thinking of a similar nested fin design, but then I got lazy.

I thought I had the photo of it put together but I am still looking. It has been in my "Cool Designs to try" folder for quite some time. Maybe I should put one together...

I saw this one too...kind of like a "Tiny Tim" design from the Wac Corporal...

(if this design/photo belongs to anyone please credit...I have a couple of questions)

ok, my bad, was thinking that maybe you were building something longer. how long is your booster airframe?
rex

what I'm seeing as a problem is that the booster is stable and will come in ballistic...if you're ok with that...I'd request a heads up .
rex

Rex R said:

ok, my bad, was thinking that maybe you were building something longer. how long is your booster airframe?
rex

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You said five inches, I made it five inches.

Rex R said:

what I'm seeing as a problem is that the booster is stable and will come in ballistic...if you're ok with that...I'd request a heads up .
rex

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I have a plan to put a streamer in the booster, should fix that issue.

streamer should work nicely. I am a bit curious though, are those standard bertha fins? the ones on mine have a root edge length of 3.5" (if yours are the same then just mount them as far forward and you'll be fine).
rex

"2 stage bertha", what genre band would that be if that were a band name?

Rex R said:

streamer should work nicely. I am a bit curious though, are those standard bertha fins? the ones on mine have a root edge length of 3.5" (if yours are the same then just mount them as far forward and you'll be fine).
rex

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Astute observation Sir.! My fin template was made from a (rough) tracing of a fin already attached to a different BB. Thinking back, it completely slipped my mind to trim it down to actual. I do wish they were not yet attached to the sustainer, but what's done is done. I'll do something fun with the booster fins.

modeltrains said:

"2 stage bertha", what genre band would that be if that were a band name?

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It crossed many boundaries when you think about it - maybe something all new?

Chad- should we expect a maiden voyage next week at the sod farm?

one wonders what colour chad will use...and if it will have a snout .
Rex

Do a little checking on booster fins.May need to trim a little off leading edge to line fins together.If fins wasn't on sustainer yet,you could mount sustainer fins
1/4 inch up from aft of airframe.

Rex R said:

one wonders what colour chad will use...and if it will have a snout .
Rex

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I found some old BB decals in my stuff, I was going to do a New BB booster with an old BB sustainer - but now that you mention it, I do miss my little pig.