Building a 6 ft replica of the Higgs Farm Square Rocket

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Nathan

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I am attempting to build a 6 foot replica of Tom Cohen's Higgs Farm Square Rocket . . .

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The original rocket is a 240 lb N motor beast. Here is Tom's original build thread: https://www.rocketryforum.com/showthread.php?121209-Higgs-Farm-Square-Rocket

There is also a Mini Higgs Farm Rocket kit made by New Way Space Models. Here's mine . . .

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The rocket that I'm building will actually be a 4X upscale of the Mini Higgs Farm Rocket which will make it 6' 4" tall. It will be built on a 4" fiberglass tube with 54mm motor tube. The square exterior will be made of 1/4" birch plywood. Fins will be made of 3/16" G10 fiberglass, custom cut by UpscaleCNC. I expect the weight to end up at about 35 lb with motor. I will be using altimeter controlled single deploy at apogee, with the altimeter in the nose. So far it sims at about 1500 ft on a 6 grain 54mm motor.
 
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Here is the internal 4" airframe with 4 fin slots cut and MMT installed. I didn't take any build photos up to this point because this part was pretty basic stuff.

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I look forward to seeing you and Tom launch side-by-side.

Yeah I guess we could drag race; this rocket on a K motor will probably only go about as high as Tom's big rocket on a N motor, like between 1000 and 1500 ft. I wish now that I had used a 75mm MMT but too late now. I will only be able to fly this on 54mm 5 and 6 grain motors. A 54mm 6XL won't fit because the upper 1515 rail button will be attached to a 1/4" threaded rod that goes through the airframe tube just forward of the MMT.

Are you continuing with the same colour theme as your mini?

I plan to paint it black and white exactly like Tom's original square rocket, but without the Higgs Farm decals.
 
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I'm sort of using OpenRocket to design this rocket but OpenRocket can't model square rockets. So in OR it is round. The nose cone is modeled using two transitions.

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OR also can't handle the complex fin design with boxes on the fins. I used LibreCAD to design the fin parts which were made by Nat Kinsey at UpscaleCNC. As always, Nat did a great job and had the fin parts cut and in the mail in just a few days. I intentionally had him make the fin tabs too big and I will cut them to the exact size on the bandsaw after I get the plywood exterior on the airframe tube and measure.

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I will be epoxying the plywood exterior directly to the 4" fiberglass airframe (without centering rings). The square exterior needs to be 5" x 5" to keep it to scale, and the plywood is 1/4". So I need a strip of 1/4" plywood between the 4" tube and the exterior plywood to make it exactly 5" x 5".

Here are four of the sections of the plywood exterior ready to go. I cut these on the bandsaw. The standoff strips were attached with wood glue and clamped. I could only get this 1/4" birch plywood in 24" lengths so there will be two of these sections on each side, eight in total. Each board is 4 3/4" x 24" and the standoff strips are offset from the center by 1/8" so that they will be centered over the airframe tube when the box is assembled.

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I built this jig to keep everything square while I epoxy on the plywood panels . . .

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For the lower plywood panels I cut fin slots on the bandsaw before epoxying them to the airframe tube . . .

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Here are the lower panels being epoxied to the airframe tube. Now it's starting to look square! I did the panels one at a time, one per day for 4 days. The wax paper is to prevent the rocket from getting glued to the jig. Epoxy can't stick to wax paper so it peeled right off after the epoxy was cured.

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Way too cool Nathan..
But I like the Higgs Farm decals..
I vote you paint like his too..

Nathan, I love the natural edge and natural feet wood coffee table..
Super beautiful man..

Teddy
 
I made this full size cardboard prototype of the nose cone shape to verify that I had calculated the lengths and angles correctly. Here it is next to the mini Higgs Farm rocket for scale. I'm pretty sure that this was the first time since jr high school that I have had to use the Pythagorean Theorem . . .

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I made this full size cardboard prototype of the nose cone shape to verify that I had calculated the lengths and angles correctly. Here it is next to the mini Higgs Farm rocket for scale. I'm pretty sure that this was the first time since jr high school that I have had to use the Pythagorean Theorem . . .

But your teacher told you you would need it someday!
 
Upper and lower plywood panels have been epoxied to the airframe. I'll use a handheld sander to clean up the epoxy on the corners. The gap between the upper and lower panels will be covered by the trim boards.

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Looks pretty square from this angle. I'll need to clean up the fin slots with the Dremel.

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No change,,
No surprise,,
Man, are you meticulous..
I'd like you to see my build "Europa Express"..
That was complex and came out nice...
But geezzz Nathan,, lol..

Teddy
 
Subscribed. I love this rocket.

That's super cool Chuck..
Now that you're home you get to see this rocket fly,,
both Nathans and Tom C's full scale...
I'm so glad you're making it to Red Glare at Higgs Farm..
I really can't wait to meet you and shake your hand and "Thank you for your service"...

Teddy
 
Hey, look up Bat-mite while you're there. I'll be watching the big blue rocket blow up. :facepalm:

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I cleaned up the fin slots with a Dremel, and cut the fin tabs down to the correct depth on the bandsaw. So now I can test fit the fins.

Next step: Build the square boxes on the fins before permanently attaching the fins.

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First fin box is done. I still need to do some fillets on the inside of the corners.

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While I'm building fin boxes I have also started working on the nose. The exterior of the nose is made of the same 1/4" birch plywood as the square airframe exterior panels. The structural interior of the nose will be a section of the same 4" diameter fiberglass tube as the airframe. The plywood exterior will be attached to the fiberglass tube with a 1/2" plywood square centering ring.

I cut the exterior panels using both the table saw and the bandsaw. I'm gluing them together with wood glue and will later add inner epoxy fillets.

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Just wanted to drop by and say "Really Cool!"

I had no desire to build anything square in planform prior to this thread. This build is unique and well executed; I dig it! ...and now I want do build something square, darnit!!!:dark::wink:
 
Just wanted to drop by and say "Really Cool!"

I had no desire to build anything square in planform prior to this thread. This build is unique and well executed; I dig it! ...and now I want do build something square, darnit!!!:dark::wink:

It is really cool, not like any rocket I've built before and definitely more fun to build than your basic 3FNC rocket. But it's not that unique; it's an upscale copy of the Mini Higgs Farm Rocket kit which is a downscale copy of Tom Cohen's original huge square Higgs Farm Rocket. So Tom gets all the credit for the super cool design.
 
Looks great!

Those box fins don’t look like plywood, what are they made of?

Reguarding the finish, the original has an nice flat finish, are you going to keep it authentic or put your signature shine on it?

Cant resist: Don’t cut any corners on the project! :roll::roll:
 
Fins and fin boxes are 3/16" G10 fiberglass.

I plan to do a polished high gloss finish, of course!
 
Do you still expect it to weigh 35 lbs? That seems like a lot for something that is only 6 ft tall. If it does weigh that much, will you be able to get a big enough parachute into the 4" tube? I'm just curious.
 
Do you still expect it to weigh 35 lbs? That seems like a lot for something that is only 6 ft tall. If it does weigh that much, will you be able to get a big enough parachute into the 4" tube? I'm just curious.

Yes I still think it will weigh about 35 lb. I have weighed most of the parts. The four fins and fin boxes alone weigh 11.2 lb. I wish now I had had them made out of 1/8" G10 instead of 3/16" because they probably would have still been plenty strong and would have saved about 3.7 lb. I initially had planned to use 1/8" plywood for the exterior but that seemed to flimsy so I switched to 1/4", which added weight.

I won't know until I'm almost finished if I will need any additional nose weight for stability. According to OR it has about 1.5 cal stability with no additional nose weight but we'll see.

I already checked and if necessary I can fit my 8 ft Iris Ultra Fruitychute in the 4" tube. According to OR with a pad weight of 35 lb it will descend at a slow 10 mph with the 8 ft chute. So more likely I will use my 6 ft Iris chute. I originally got the 6 ft Iris chute for my Frenzy XL but it's really too big for that so I can only use it on calm days.
 
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Nose exterior is completed except for the top. I used the bench sander to smooth out the joints and make the ends flat. Turned out pretty nice. After I assemble the nose I'll use wood filler on the gap between the upper and lower sections to clean up that joint.

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