SBB Nosecone and BT-80 tube, what to build??

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Came across a BT-80 sized nosecone in a random hobby store for $5 so I bought it. From the rounded shape, I'd say it's a SBB nosecone. Ordered a BT-80 tube, which should arrive Thursday. I don't want to make a SBB clone, might as well do something semi-original, but can't think of a decent fin design (except maybe a curved shape) that works with the blunt nosecone shape well.

It's getting a 24mm MM for D and E (and F) motors, and therefore, through the wall fins would probably be a good idea. Any ideas?
FYI: The BT-80 tubes are a pair, and I have a coupler, so I am thinking of having it split at the coupler on the ejection charge (which might allow the upper half to be a payload bay). Anyhow, trying to avoid the SBB shape, but looking around I can't find anything that looks "right".

Any help is appreciated!
 

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Looking around on the forum, this was of interest:

If I could build these style fins out of basswood rather than balsa, that might work. I considered the "Fat Boy", as an option but, I already have a Big Daddy, which is essentially the same rocket. The trick will be figuring out how much I need to add to each fin to make them through the wall into the MM tube.

Anybody know the dimensions from a BT-80 to a 24mm tube off the top of their head? I'll likely need to do some careful measuring regardless.
 

KenECoyote

Well-Known Member
TRF Supporter
Joined
Mar 18, 2015
Messages
3,541
Reaction score
869
Location
New Yuck (North of the Sitty)
Quest Tomahawk upscale? I plan to do a BT-80 version and already have the parts too.
167889-ea3ce2c8097ca0250c19bb7c43b06e1f.data
 

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Oooh, that's not bad, although I might find the tailcone a little tricky to do correctly without adding a lot of weight, but then again, this might be an E12 motor minimum build regardless. Definitely something to consider.
 

RocketTree

C.A.R. L1
Joined
Feb 22, 2020
Messages
339
Reaction score
580
Location
Canada
You beat me to it! I was just going to suggest the Tomahawk as well. Aside from the Fat Boy, this is my absolute favorite design with the BB 80 nose cone. Here is a two stage version...

TOMAHAWK2B.png

DSC_0185.JPG

Based on this version:

1659368725992.png
 
Last edited:

TigerHawk

Reliving the good ole days
Joined
Jun 19, 2021
Messages
1,422
Reaction score
825
Location
Tennessee
Build a Estes Ranger upscale, with one of these cluster mounts and fin & CR set,

 
Last edited:

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Hrrrrmmmm. The fin design is easy, so I'm liking the idea of a Hellfire. Although its a bit stubby, I can see that if I cut the second BT-80 Tube in half, I can still make a (smaller) payload area by having it split right after the upper fins. I have to work out a few sketches and see what works once I get all my pieces in place. Simple paint job too -- OD green with three yellow rings and half the nosecone gets painted white or black.
 

Tractionengines

Well-Known Member
TRF Supporter
Joined
Aug 29, 2020
Messages
701
Reaction score
597
Location
Northeast Ohio
If you go after a scale version... Just WATCH STABILITY, the Hellfire missile, as a rocket, needs some some extra help. I would start with 1) Make the main fins 25% taller. (Away from the body tube.) 2) Make the front fins 20% shorter. (Along the body tube.) 3) "try" to go easy on the glue in the aft end. 4) be prepared to add some weight up front.

Matte finish on everything, but "very high-gloss black" on the Seeker.

(This was my plan at some point, but I haven't built it yet.)
 

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Every time I build from scratch, it's never been a "true scale model"... Usually, I use an idea of something I've seen in my head for inspiration and then I build what "feels right". I also noticed the tail fins of the real thing look small. There's a good amount of fin area, but it's along the length and not perpendicular to the body. I've got some pre-cut balsa pieces from a bull pup that might work as the upper fins. But again, sometimes I start a project and then it just turns into something else because that's how the creative process grabs me.
 

neil_w

OpenRocketeer
TRF Supporter
Joined
Jul 14, 2015
Messages
14,511
Reaction score
7,999
Location
Northern NJ
Looking around on the forum, this was of interest:

If I could build these style fins out of basswood rather than balsa, that might work. I considered the "Fat Boy", as an option but, I already have a Big Daddy, which is essentially the same rocket. The trick will be figuring out how much I need to add to each fin to make them through the wall into the MM tube.

Anybody know the dimensions from a BT-80 to a 24mm tube off the top of their head? I'll likely need to do some careful measuring regardless.
OpenRocket will do this for you, and generate fin templates.
 

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Never seen the Maxi Streak before. Has anyone tried building that using Tongue Depressors instead of balsa fins?
 

Back_at_it

Well-Known Member
TRF Supporter
Joined
Jul 16, 2019
Messages
1,425
Reaction score
1,376
Location
Chicago Burbs.
The fins are very thick. I believe they are 3/16" so you would need to stack a lot of tongue depressors together. They are also a bit larger than they look.

A BT80 upscale would put the fins at 11.5 inches in length and probably be 1/4 inch thick. I have one planned for the near future.
 

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Ok, this weekend, I started building something with the nosecone and BT-80 tubes. Wasn't planning a build beforehand, just seeing how pieces fit together and then all of a sudden, I start gluing things and it started to take a shape, kind of organically. Here's what I've got so far.....

It's going to take 24mm D, E, F motors, there's a payload bay, I opened up the plastic nosecone to add some clay weight, which I used gorilla glue to hold in place. While that ring-fin *should* be enough fin area to keep it stable, I'm going to add more pieces on the outside of the ring. I'm thinking of cutting up some of those paper drinking straws and adding to the outside of the ring, between each of the 6 balsa fins. And instead of a single launch lug, I'll put 4 around the body tube as well for additional drag/stability.

I'm making this a "low and slow" build. Don't know what it weighs yet, but it's still much lighter than my Big Daddy, so, no problem getting this off the pad.
 

Attachments

  • IMG_5182.JPG
    IMG_5182.JPG
    45.9 KB · Views: 0
  • IMG_5183.JPG
    IMG_5183.JPG
    49 KB · Views: 0
  • IMG_5184.JPG
    IMG_5184.JPG
    122.4 KB · Views: 0
  • IMG_5185.JPG
    IMG_5185.JPG
    49.1 KB · Views: 0

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
I think it needs some fins just below the payload bay, that area looks too clean given all the busy going on at the bottom.
 

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Latest updates. I think this is about as far as I want to take it. Need to see if this will actually fly and not just flip over.
A quick paint job, a shock cord, a chute and a D12-5 and we'll have to try it out....
 

Attachments

  • IMG_5186.JPG
    IMG_5186.JPG
    42.4 KB · Views: 0
  • IMG_5187.JPG
    IMG_5187.JPG
    58.9 KB · Views: 0

techrat

Well-Known Member
TRF Supporter
Joined
Jul 18, 2022
Messages
591
Reaction score
428
Update: The Drag Queen passed the swing test, so I painted her the ugliest neon colors I could get my hands on and she'll fly at September CENJARS.
 
Top