Whitetip - a 38mm scratch build with 3D Rocketry fins

This is a design centered around the most excellent fin sets that Bill at 3D Rocketry offers. I've had the parts for over a year, and finally got the time to start the assembly process. Here's the preliminary RockSim file

View attachment Whitetip v3.rkt

And here are the parts - it's a group effort:


48" x 3" Bluetube (BMS)
3" Bluetube coupler (BMS)
2 x LOC 3" NC (Wildman)
Bulkheads and centering rings (LOC/Wildman)
Fins (3D Rocketry)
Retainer (Giant Leap)
Vinyl (Stickershock)

Yep. Parts from six of the fine vendors that we all love and give $ to. Actually, the original retainer for this build went into my Wildman Jayhawk, so I need to order another one. And Mark, check your e-mail, as there is an order coming your way.

Here are the parts as they currently exist. Off to the garage to visit Mr. Compound Miter Saw and Ms. Belt Sander.

Yeah, I have the same set, actually a 3" and 4" set from Bill. I have somewhat of an odd-roc in mind whenever I get around to building it.

Look forward to watching this build--like the design. Kind of a flowing/aerodynamic Talon.

OK, make that seven vendors. Forgot Teddy at OneBadHawk, who supplied the harness.

Got the parts cut to length. This was an iterative process that involved three trips out to the garage, coupled with updating the Rocksim file to match reality. And some time with a drill and a sanding drum.

View attachment Whitetip v4.rkt



After dry fitting the pieces - mostly the motor mount, tail cone, and fins, it was time to whip up some epoxy and start securing things together. First, I had to find the dang epoxy. I've got the scale out to weigh parts, so why not weigh the epoxy?



The forward centering ring only got epoxy on one side because otherwise I need to notch the TTW fins. The rear CR is epoxied in place, and the center is free-floating, as I want to be able to either foam the fin can (most likely) or do internal fillets. Probably foam.



You know those people whose build threads show their tidy work area and careful build process? Yeah, that's not me.

While I had some epoxy, I repaired a fin on my 4-29SS that suffered from a close encounter with the ground when only one motor lit, and also secured a permanent motor adapter (38-29) into my King Kraken Klone. (My mistake was using thin wall tubing rather than LOC 3" tubing. Anything more than a G and it tried to rip itself to shreds.)

Next up: Filling the spirals, cutting the fin slots, finding some welded eye-bolts and a U bolt for the harness attachment.

I use that same scale.

OK, print out fin marking template. Cut it out. Too small. Print out second copy, unchecking box for "Scale to fit page". Mark locations of fins, and draw first line. Use actual fin to figure out where the second parallel line should go.



Next, I got to try out my recently arrived Dremel 543 rotary blade. It works pretty well! As always, when using power tools, WEAR EYE PROTECTION. Full face is better - ask me about the angle grinder, the railing, and where the bottom half of my front tooth used to be.



Next, add just enough water to some wood filler that I can push it into the seams for the first coat.



While all this dries, I will be doing some or all of the following:

• Changing the oil and spark plugs in my car
• Wandering out to Home Depot to get a U-bolt
• Walking the dogs

Probably go to HD to get U-bolt first, which will warm up oil. Hmmmm

Well, got the u-bolt. Went to change the oil, but did not have a filter - glad I checked before I drained the oil. Walked the dogs. Dealt with the least pleasant aspect of owning three dogs of 40 lbs or more, in conjunction with melting snow. Fed dogs, fed self, got a filter, now back to the car. More rocket stuff later, I promise.

Last post of the day. Oil changed, wait - you don't care about that, do you?

Sanded first coat of wood filler, applied second coat. Sanded off second coat.

Epoxied motor mount in place - top CR only. Cut out template for fin alignment from payloadbay.com. Taped that to a $.50 sheet of foam board from Dollar Tree, and cut out a fin alignment guide.

Dry fit the fins, slid on the guide, and mixed up some two part foam. Pour and wait.



While all this is going on, worked on artwork, and sent order off to Mark @ stickershock.

Home from work, was able to accomplish final assembly on the fin can. First, a picture of the rocket (sans tailcone) after the foam dried.



Then, cut the foam away where it overflowed. Spread some epoxy on the inside of the body tube, and on the motor mount, then slide the center centering ring into place. Tap into place using a Popsicle stick and a hammer encourage the centering ring to go all the way down to the fin tabs.



Dry-fit the tailcone. Discover that no matter how carefully I measured and planned, it's 1/4" too long. Freehand cut with a utility knife.



Test fit again. Epoxy the top of the centering ring, wipe around the inside of the body tube, and load up the top CR (leaving the tailcone upright should allow the wet epoxy to flow and fill the gaps between the tailcone and the MMT). Fit the tailcone. Admire a good-looking aft section!

Taped out where the fillets are going to go.



Got two fillets done last night, then stopped. I have learned the painful lesson that when I am tired, things go awry. Fortunately, I didn't need to learn it again last night.



Taking a break now for a couple weeks while I'm on a business trip. When I get back, I'll finish the fillets, then I think I'm going to see if anyone nearby has a vacuum bagging setup that they would be willing to let me borrow...

That thing looks pretty sweet! I hear ya on the tired factor messes things up, happens to me all the time.

Got the other two fillets done last weekend (like 8 days ago) after returning from a business trip, and tried to primer the top section.

Can still see some spirals. Need to decide if I want to fill and sand some more, or just be OK with them.

May add pictures of this stage of build. Currently home sick, disinclined to exit La-Z-Boy to try to take pics.

Just ordered CF to do tip-to-tip on the fins. I've got a launch coming up this weekend (19th), so I'm thinking I'll give that a try on Easter weekend. May try to build a jig, as per one of John Coker's excellent tutorials, to hold everything while I lay up the CF. Then I'll probably need to go to my storage space and grab my router and router table... It's always something.

CF and veil is in. Stay tuned for my first attempt at tip-to-tip! Guaranteed to be amusing...