Shepherd of Fire - Mudrock 2016 Project

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patelldp
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Shepherd of Fire - Mudrock 2016 Project

Postby patelldp » Mon Feb 01, 2016 9:44 am

Black Rock is the U.S. Mecca for amateur rocketeers. A waiver that 99.99999% of us could never break, expansive recovery land, and remoteness make Black Rock a rocketeers dream...and it's my goal to get there someday.

That someday is (hopefully) this year. I've been chatting for a long time with friends that I made here on the East Coast (and some on the West that I have never met) that have since moved West and this will be an opportunity to hang out with them once again at a rocket launch. I chose Mudrock instead of BALLS because I have been advised that the weather is favorable and I assume the crowds are lighter.

I can't go to a launch without planning to fly something, right? Well let's design a project!

Here are my design goals:

  1. Use standard 76mm motor tubing
  2. Flying case design
  3. Composite nozzle design using phenolic and graphite
  4. Composite fin can with phenolic fin blanks machined to hide the carbon fiber layups
  5. AIM Xtra 2.0 tracking and deployment with timer backup
  6. Survive the boost and recover the rocket!

At this point I have the 5-foot motor/airframe tube, nozzle phenolic, nozzle graphite, bulkhead and nosecone adapter aluminum, and fin can FWFG tube on hand. I have ordered the 3/16" thick phenolic fin material from Mike at www.macperformancerocketry.com and had it sent to a friend to be machined. I still need to buy a 3" FWFG nosecone and a piece of aluminum at least 3.25" OD in order to make the aft pin ring/nozzle retainer/boat tail.

Stay tuned!
Dan Patell
TRA 10904 L3

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patelldp
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Location: New York

Re: Shepherd of Fire - Mudrock 2016 Project

Postby patelldp » Mon Feb 01, 2016 10:14 am

Here's a sneak peek at what I have planned for the fins. The material will be 3/16" cotton canvas (X Phenolic), chosen for its resistance to ablation. Pockets will be machined into the "meat" of the fin blank to permit me to lay up carbon fiber and have it hidden from the aerodynamic erosion caused by the possible Mach 3+ speeds this rocket will attain. Just in case, Cotronics epoxy will be used to adhere and fillet the fins (4525) and laying up the CF (4461).

Here's the Rev. 0 of the fins. I plan to make a few tweaks to the design before I have them cut.

SOF Fins - 3.jpg


SOF Fins - 2.jpg


SOF Fins - 1.jpg
Dan Patell
TRA 10904 L3

SMS Engineering
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Re: Shepherd of Fire - Mudrock 2016 Project

Postby SMS Engineering » Mon Feb 01, 2016 4:48 pm

Dan I would radius the "pocket" corners to prevent stress cracks in the phenolic from forming .
Good design .

Eric

DBMcCann
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Re: Shepherd of Fire - Mudrock 2016 Project

Postby DBMcCann » Mon Feb 01, 2016 7:26 pm

sounds pretty crazy. I like it.

What plans do you have for the nozzle?

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patelldp
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Re: Shepherd of Fire - Mudrock 2016 Project

Postby patelldp » Mon Feb 01, 2016 10:46 pm

SMS Engineering wrote:Dan I would radius the "pocket" corners to prevent stress cracks in the phenolic from forming .
Good design .

Eric


The pocket is chamfered. The carbon will go up to the edge of the full thickness and the whole thing will be bagged. I'm thinking 4 layers of CF on each quadrant and I'm assuming all of the strength comes from the CF, not the phenolic.
Dan Patell
TRA 10904 L3

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patelldp
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Location: New York

Re: Shepherd of Fire - Mudrock 2016 Project

Postby patelldp » Mon Feb 01, 2016 10:47 pm

DBMcCann wrote:sounds pretty crazy. I like it.

What plans do you have for the nozzle?


The nozzle will be XX phenolic with a graphite insert. The insert will be a male taper and the phenolic will be a female taper. Epoxy will hold the pieces together to be match machined, but the taper will seal everything upon startup.
Dan Patell
TRA 10904 L3

SMS Engineering
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Re: Shepherd of Fire - Mudrock 2016 Project

Postby SMS Engineering » Tue Feb 02, 2016 9:29 am

patelldp wrote:
SMS Engineering wrote:Dan I would radius the "pocket" corners to prevent stress cracks in the phenolic from forming .
Good design .

Eric


The pocket is chamfered. The carbon will go up to the edge of the full thickness and the whole thing will be bagged. I'm thinking 4 layers of CF on each quadrant and I'm assuming all of the strength comes from the CF, not the phenolic.


Maybe I miss worded my thoughts. I would use at least a .375 ball noes endmill when machining the outsides of the pockets. I would be most concerned with the 90 degree inside corner . Think of airplanes with round windows vs the old square design that destroyed multiple aircrafts .

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patelldp
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Location: New York

Re: Shepherd of Fire - Mudrock 2016 Project

Postby patelldp » Tue Feb 02, 2016 9:55 am

SMS Engineering wrote:Maybe I miss worded my thoughts. I would use at least a .375 ball noes endmill when machining the outsides of the pockets. I would be most concerned with the 90 degree inside corner . Think of airplanes with round windows vs the old square design that destroyed multiple aircrafts .


Yep, understood. Square corners are more likely to fail than a rounded corner would be. A ball end mill will be used to machine the fins, but as an added measure the inner cavity is chamfered, as shown in this picture:

SOF Fins - 1.jpg
Dan Patell
TRA 10904 L3

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patelldp
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Re: Shepherd of Fire - Mudrock 2016 Project

Postby patelldp » Wed Feb 03, 2016 9:54 am

Fin stock is on its way to my friend to be CNC'd. These fins will be complex to machine primarily due to the large and thin web of the fin. Eager to see how they turn out.

Things to buy:
1. 3" Conical FWFG nosecone (anyone need a 3" coupler or an aluminum tip?)
2. Cotronics 4525 and 4461 ($200 of epoxy, yikes...)
3. 3.25" OD x 6" chunk of 6061

More pics as parts get made!
Dan Patell
TRA 10904 L3

dixontj
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Re: Shepherd of Fire - Mudrock 2016 Project

Postby dixontj » Sun Feb 07, 2016 1:36 pm

Sounds fabulous. Really like the fin approach!


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