Building a 6 ft replica of the Higgs Farm Square Rocket

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All four fin boxes are done except for doing fillets on the inside corners of the boxes. Fins have not been glued on yet and the nose is just a plywood shell but here is how it looks so far. Next I need to work on the internal structure of the nose.

In this photo you can also see the upper rail button which is attached to a threaded rod that goes through the airframe just forward of the motor mount.

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Made the plywood top of the nose today. The top has a square shoulder which fits snugly into the top of the nose shell. There will be a single 1/4" threaded rod running all the way through the nose to help hold everything together. The av bay sled will attach to the rod.

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This looks great. Anyone know what inspired Tom to come up with this crazy thing in the first place?

I'll have to ask. Mostly he just likes unique-looking scratch builds. He steers away from 3FN and 4FN designs. Lots of ring fins and tube fins. I think he just wanted to see how a square rocket would perform.
 
The 1515 rail buttons need to be 4" out from the inner fiberglass airframe to clear the corner of the nose cone. The rail buttons are attached to 1/4" threaded rods that attach to the inner airframe. The rods are covered with a section of square dowel. I used the drill press to drill 1/4" holes through the length of the square dowels (I knew my pen making skills would come in handy in rocketry sooner or later).

The aft rail button is attached with nuts on both the inside and outside of the airframe. The forward rail button is just forward of the motor mount and I couldn't reach all the way down into the 4" airframe to attach a nut so instead that one goes all the way through the airframe with a nut on the other side. Unfortunately I will be limited to 54mm 6 grain motors because that threaded rod will prevent me from ever using a 6XL motor.

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Notice where I patched holes in the airframe in this photo. That's because I made the mistake of drilling the holes before attaching the plywood shell to the airframe, then afterwards realized that the holes weren't quite exactly on the corners. So I patched those holes and drilled new ones on the other corners.

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What is stopping you from locating the forward rail button and standoff just south of there you have it now, located on the square airframe, secured into the inner airframe tube like you have it on the aft rail button?

Looking nice BTW.

The forward rail button is just forward of the motor mount and I couldn't reach all the way down into the 4" airframe to attach a nut so instead that one goes all the way through the airframe with a nut on the other side. Unfortunately I will be limited to 54mm 6 grain motors because that threaded rod will prevent me from ever using a 6XL motor.

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What is stopping you from locating the forward rail button and standoff just south of there you have it now, located on the square airframe, secured into the inner airframe tube like you have it on the aft rail button?

Looking nice BTW.

If the forward rail button were secured to the inner airframe like the aft rail button then I would need to reach way down into the 4" tube from the top to attach and tighten the nut to the threaded rod. And my arm doesn't fit.
 
You could take a long piece of flat aluminum, and cut a notch in it the width of the nut, and reach inside with that. Or place your button a little higher on the rocket...
 
You could take a long piece of flat aluminum, and cut a notch in it the width of the nut, and reach inside with that. Or place your button a little higher on the rocket...

I can actually fit my arm far enough down the tube that I might be able to reach that area with a socket wrench. I'm going to try that.

It'll fly, but I'm worried about the bucket loader....

Ha, I think you are referring to my ill-fated Onyx which came down fast with no chute at the sod farm and managed land in the bucket of a loader, the only piece of heavy equipment in the field that day. It hit the bucket so hard that it rung it like a church bell. I repaired that Onyx after about a year. Then it landed in the pond, along with a Chute Release. That was the end of the Onyx.
 
Glued and miter cut the trim pieces for the middle of the rocket. I'm going to have to do some cutting to work around the rail guide standoff.

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Nathan,

Awesome build! Will this be flying at Red Glare in April?

Scott
 
Nathan,

Awesome build! Will this be flying at Red Glare in April?

Scott

I might be done building by then but paint jobs usually take me 4 to 6 weeks so it won't be finished in time for Red Glare.
 
I epoxied the second square centering ring into the lower nose shell and glued the upper and lower nose shell sections together. At first I wasn't sure if I would be able to use the second square centering ring because if the nose shell sections weren't exactly square then the inner 4" fiberglass tube might not fit through both rings. But it worked out okay and everything fits. I still need to do internal epoxy fillets on the joint between the upper and lower nose shell sections.

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Working on fillets . . . I'm doing epoxy fillets on all 10 joint corners on each fin box. With the normal external and internal fin fillets and that adds up to 16 fillets per fin for a total of 64 fillets! The Aeropoxy takes all day to cure so I'll be doing fillets for a long, long time.

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Working on fillets . . . I'm doing epoxy fillets on all 10 joint corners on each fin box. With the normal external and internal fin fillets and that adds up to 16 fillets per fin for a total of 64 fillets! The Aeropoxy takes all day to cure so I'll be doing fillets for a long, long time.

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Wow just imagine how much better you are going to be at filets, you know because you have a lot of room for improvement.
 
Gluing on the trim boards to close up the middle section. I'll use a little wood filler to clean up the corner joints.

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Here is the inner 4" tube for the nose. The plywood nose shell will be epoxied to the inner tube by the two square centering rings in the shell.
The aft bulkhead is removable and there is a fixed bulkhead on the forward end that is not visible from this angle. The threaded rod is bolted to both bulkheads and will also be bolted to the plywood cap on the top end of the nose. The av bay sled will be in the shoulder of the nose attached to the single threaded rod. On ejection, the force on the removable rear bulkhead from the recovery harness will be transferred to the fixed forward bulkhead by the threaded rod.

Deployment will be single deployment at apogee. Not a problem since it will never go more than 2000 ft. I don't have redundant electronics because it will have motor ejection as backup. I still need to drill the vent holes, shear pin holes, and holes for the arming switch wires. The switch will be on the lower side on the nose shell.

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Have you considered doing the recovery the same as the full size rocket - separate chutes for the NC and the main rocket. It would be a nice way to really model the original.
 
Have you considered doing the recovery the same as the full size rocket - separate chutes for the NC and the main rocket. It would be a nice way to really model the original.

I thought about that because I'll probably be using a 6 foot FruityChutes Iris chute and that's just barely enough chute for this rocket. But I don't know how I could do a separate nose cone chute. The deployment charge is firing downward from the nose bulkhead so if the main chute harness is not attached to the nose then there would be nothing to pull the main chute out of the tube. The motor ejection would blow it out but I would prefer to use that just for backup.
 
You could run an e-match wire down the tube under the chute. I do this all the time.

Another option would be a free bag setup, or just placing the nose chute under the main chute so it had to pull the main or to get out...
 
Have you considered using a deployment bag? If you “free bag”, the piolet chute could bring down the nose cone separately.
 
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