Oh no... I'm building another upscale. Black Brant II (BT-60)

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K'Tesh

.....OpenRocket's ..... "Chuck Norris"
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Estes Black Brant II holds a special place in my heart, I've built a number of them over the years they were produced, but this was before my skills really developed. Now I feel it's time to tackle this one again... This time, my style... A BT-60 upscale.

BB2@.gif

Some History:
You may have read my title (Seagulls Beware...) and wondered what that's all about. Well, I D**N near shot one down once with my last BBII launch. I was living in Klamath (pronounced: clam muth) Falls Oregon (pronounced: "Or uh gun") at the time. As anyone who lives there can tell you, they've got seagulls. In the mornings they fly from their resting areas to the local dump, and feed. Then in the evening they fly back to the lake for the night. Some buddies and I were out launching one evening, just as a flock of them was flying over, I hit the pickle button, and the rocket flew straight for them. I wasn't trying to hit them, we honestly didn't even know they were there until the rocket was on its way up. I truly wish that I had a video camera, because the results were AFV winning type Funny (no crotch hit though).

We all watched as the rocket streaked upwards and all said something to the effect of "Say, would it be funny if...." just as the rocket crossed in front of one of the birds. The startled gull did its impersonation of Jonathan Livingston Seagull (an amazing barrel roll) and squawked its surprise at the missile that just missed it by the narrowest of margins. We spent several minutes trying to catch our breath long enough to capture the rocket as it floated down we were laughing so hard.

Estes Black Brant II dimensions:
Length: Catalog has it as 24.875" My measurements come out to ~25" even
Nose Cone:
6.5" (PNC-55BB Conical )
BT-55 Body tube
1.875" Payload Section​
13.5" Main Body​
0.875" Motor​
0.25" plastic custom Coupler Section
0.75" plastic conic Boat Tail (BT-55 to BT-50)
Fins make up the remaining ~1.25" of the length.


Upscaled to BT-60 (123%)
Length: ~30.75"
7.995" (Semroc BNC-60SM 8" Conical)
BT-60 Body Tube:
2.3" Payload Section​
16.605" Main Body​
1.076" Motor​
0.3075" Coupler Section
0.9225" Boat Tail
Fin will make up the remaining ~1.54" of the length.

I'm trying to find a nice Mylar balloon for the parachute (18" round Canadian Maple Leaf).

1676505213266.png

I'm planning on photographs as soon as I can (got the body tubes cut down, need the centering rings, and nosecone before I can really get started).
 
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Really, really nice! I'm a sucker for all Black Brants, and wish you well. Great idea for the 'chute, BTW!
 
Sweet... Would you mind posting the templates/dimensions for the fins? This looks like something I can save to a txt file for a built in a few months!
 
Sweet... Would you mind posting the templates/dimensions for the fins? This looks like something I can save to a txt file for a built in a few months!
Have you tried Open Rocket yet?
 
Ok, here's what I've got so far...



This is based on the original, not upscaled dimensions, and the fins and the antennae were just eyeballed, and not accurately measured. To create the fins, I created one of my phantom body tubes (this one is located aft of the engine mount tube (.0001" long)) to that I attached the fins (again, I just guesstimated the look). If you were to look at the fin's template, you'd see that they are mounted to the engine mount, cutting completely through all other parts of the engine mount assembly (save the thrust ring) and the main body tube.



My idea for the real fins is to simply print the fin templates posted on JimZ's site, and use a photocopier to blow them up to the correct size.

The antennae are .5mm thick "fins".

To do the Wasp Waist, I created parabolic transitions, back to back and added shoulders to them.



I've no idea exactly how I'll do the real parts when it comes to that. I have a theory using two rubber "O" rings that may work (or not).
 
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I'm now pursuing the idea of 3D printing the Wasp Waist/coupler and the tail cone.

Might be a while be a while before I get them, but you can ask Landru about them if you want to make some for you.

Pointy Side Up!
Jim
 
If I can get at least 5 orders, I cam make a 3D Printed BT 60 sized wasp waist and tail-cone set for $16. Pm Me if you are interested.

Untitled.jpg
 
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K'Tesh...you've convinced me. I finally need to get around to building a Black Brant II after all these years. BT-60 it is. That will be a nice size and fit right in with my selection of AT motors. Great idea!
 
K'Tesh...you've convinced me. I finally need to get around to building a Black Brant II after all these years. BT-60 it is. That will be a nice size and fit right in with my selection of AT motors. Great idea!

Just don't blindly use the fins I used for the .orc file. Again, it's an approximation. So, I'd go to JimZ's site print the fin pattern, then blow them up 123%.

Can't wait to see your results!

Pointy Side Up!
Jim
 
*sigh* SEMROC sent me a set of fins that fit a BT70 tube...no help here. Plus I'll have to have Sandman make me a cone. SEMROC does have a BT70 boattail so I'm good there.

Tried Open Rocket, didn't like it, very clumsy. I'm getting a new printer so I can get VCP running(I'm a little biased to VCP, I know Gary :) )
 
Confession time... I'm not a professional Open Rocket designer. In reviewing the design, I realized that my dimensions were just a tad "off" (I had one side of the Wasp Waist at 1.637", and the other at 1.647"). I deleted the old .ork, and uploaded one that I corrected both parts to be 1.637".

Fins are still unchanged... Only a guess.

Hopefully that won't be a problem for anyone.
 
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I love the Black Brant II, the Estes kit was my first D powered kit. It turned into a lawn dart on its first flight, but that D power was awesome. I'm building another one right now. Those antennae are driving me a little nuts though, I've broken 2 off on seperate occasions. I'm thinking about trying to make them TTW attached, only wish I had done it sooner in the build instead of after I'm done with assembly.

I'm going to use it as my scale flight for NARtrek.
 
My old technique for handling the antennae was to use bent out paperclips and go TTW with them. I've only had one ever come loose on me, but several have had paint issues (a Sharpie fixed that).
 
I need at least one of these sets, two if it turns out that the Black Brant III had the wasp waist too.

According to ROTW, The Black Brant III is 10.2" in diameter form the base of the nose cone until you get to the top of the nozzle at the other end of the rocket.
 
Landru's 3D printed Wasp Waist and Tail Cone arrived the other day... Nice looking parts.

Here's what it looks like in place...


And the parts alone (tape added for improved fit)

 
thats a pretty slick tailcone, also I've been keeping an eye out at doller stores for that mylar balloon, but so far I've only seen mylar with lots of lil maple leaves on it, if I ever see one more like the one you posted I'll be messaging you.
 
thats a pretty slick tailcone, also I've been keeping an eye out at doller stores for that mylar balloon, but so far I've only seen mylar with lots of lil maple leaves on it, if I ever see one more like the one you posted I'll be messaging you.

Thanks!

One thing about the 3D printed parts, there was a single "seam" line (recessed) where the printing started and/or stopped for each level. With the BBII, I can simply hide it under a fin. I've made a suggestion to Landru to deliberately create a raised ridge there for parts that wouldn't be able to hide (e.g. nosecones). that could be sanded off. I've yet to sand these parts as I've been reading (school work) a lot lately (and I've got a lot more to do tonight/this weekend).

Pointy Side Up!
Jim
 
Ok. Two years to the day since the last post on this project, I finally managed to create a .ork file that I can live with. The fins are attached (surface mount) to a "Phantom body tube, as OR will not allow them to be attached to a transition. I had to create "Air Fins" to get the markings to display correctly on both sides of the fins. My skills with OR have also improved to the point that I can get decals to look right and be applied in their correct locations. To sum it up, I'm happy with the .ork file.




The bad news is, I'm currently in China, and my rockets are in the USA. So, no idea when I'll be able to get my hands on them, and resume building.

View attachment Estes Black Brant II (No. 1958)(BT-60 Upscale, Decaled).ork
 
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