Black Brant III

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HeavyLight

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So I've gotten very enthusiastic about this once I started drawing it up. I was thinking about something to start working on that can be used as a good L2 rocket. It's a 4"/54mm scale BBIII; the scale ratio being about 1/2.6. It presents some unique problems in regards to some of the parts and the fact that I want to keep it on a budget. The airframe is going to be made of phenolic because fiberglass is really expensive and according to the FAQ at PML phenolic will do for flights that don't intend to go trans or supersonic. As it stands, this is designed for high H through probably low and mid K motors and goes Mach 0.8 at best. It's also over-stable because the only conical nose cones out there that I could find are made of fiberglass, which brings the CG forward significantly. To fight that I originally wanted to make the nozzle bell out of aluminum but then I read the TRA rules that said metal can only be used to ensure structural integrity (at least that was my understanding). So I changed the material to acetal a.k.a Delrin. I want it to be like the Estes model in that it has a shoulder that fits into airframe. It still has a lot of work to go before it's ready but I've got plenty of time and a huge community of rocketeers to help me. :)

View attachment BBIII.ork
 
Looks like a fun project. I'll be interested in seeing how you make the nozzle bell. The fiberglass nose cones are the only conical for 4" that I know of. I just ordered one for Binary Effusion.
 
Looks like a fun project. I'll be interested in seeing how you make the nozzle bell. The fiberglass nose cones are the only conical for 4" that I know of. I just ordered one for Binary Effusion.

My brother builds combat robots and has a friend who machines all of his things. I'm talking to him about getting it machined nice and pretty.
 
I'm in... :pop:

I don't want to get anybody's hopes up just yet. I intend this to be my whole summer project and there probably won't be a build thread for a while. The purpose of this was to figure out what to use as materials. Toward that end I have a couple of questions.

1. Of the non-fiberglass materials, which is best for this kind of application? (PML Quantum, Phenolic, or Blue Tube)
2. Would a Wildman/Performance Rocketry 4" nose cone be compatible with those?
 
I don't want to get anybody's hopes up just yet. I intend this to be my whole summer project and there probably won't be a build thread for a while. The purpose of this was to figure out what to use as materials. Toward that end I have a couple of questions.

1. Of the non-fiberglass materials, which is best for this kind of application? (PML Quantum, Phenolic, or Blue Tube)
2. Would a Wildman/Performance Rocketry 4" nose cone be compatible with those?

I haven't used Quantum. I've used phenolic from Giant Leap once, but haven't flown it yet. I will say the spirals were a lot more pronounced than I expected. I've also used Blue Tube once, and flown it a couple of times. The first time I forgot to attach the chutes, but there was no damage. It seems pretty tough. I have heard it can swell with humidity, but I put sanding sealer on it before I painted it, and haven't noticed any issues.

https://www.rocketryforum.com/showthread.php?53648-As-yet-unnamed-scratch-build&p=542943#post542943

https://www.rocketryforum.com/showthread.php?49705-Personal-launch-report-SARG-launch-02-16-13
 
I've decided to go with the PML quantum tube. I've also determined that I should be able to use aluminum for the bell if I make it integrated into the motor mount. That would make it a structural component and not a violation of the rules if I interpret them rightly. Anyway, the only thing I have left to find out is if a Performance Rocketry nose cone is compatible with PML tubes. Otherwise, it's time to enter Phase 2: Budget and Savings. :)
 
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