Rocket Team Vatsaas Commander Kip Quasar's Galactic Zephyr

Airframe

Design

To construct the airframe of the Zephyr, I will be employing a technique that a technique that I have used effectively on smaller cigar-shaped rockets. In some ways, this is a very simple 6-inch diameter rocket with a complex foam-and-fiberglass contoured skin. A 6-inch central tube runs the length of the airframe. Inside this tube is the 4-inch motor tube, and the nose cone is attached at the opposite end. The fins are anchored through-the-wall to the motor tube. The rocket separates in the middle to deploy a drogue chute, and the main chute ejects from the nose. Pretty conventional.

Here's everything that makes this rocket unique from any other 3FNC rocket: Around the central tube is a stack of foam that has been shaped into a streamlined cigar-shape and reinforced with a fiberglass skin. Some craftsmanship and artistic aptitude are required, plus a few specialized tools and fixtures. But overall, this is really not a very complicated bird.

Below are some drawings I made that illustrate the main construction components of the Zephyr. In addition to the central tube, there are six central payload bays (three in the forward section and three aft). This is more than required. I cut three 3 5/8-inch holes in each central disk to reduce weight, and used the holes to mount three 3 5/8-inch tubes in each disk. At least one will be used to house avionics. The rest may just hold good luck charms.

This foam-shaping process is essentially the same one I used when I made the [Happy Birthday Party Napkin Rocket of the Apocalypse and The Rocket Formerly Known as Black. Those rockets are much shorter, but not much thinner.

At right are photos from the early foam-shaping process. I've documented the foam-shaping process pretty thoroughly [HERE!] so I'm not going to recreate that discussion again here. But to summarize: First you create a large stack of foam around the core tube. The foam stack is mounted on a shaping fixture that has templates on either side matching the profile of the airframe. A hot wire cutter is dragged down the templates, slicing the outline of the airframe into the foam. The foam stack is turned and the process repeated until all the ridges in the foam stack are shaved off.

I made a sanding fixture matching the contour of the airframe. Sandpaper is glued to the flat surface of the fixture. The airframe is mounted on a high-speed sanding lathe which rotates the airframe at about 700 rpm. The sandpaper is pressed against the airframe as it rotates and the assembly is smoothed very quickly.

Click on the image for a larger view.

At right is the assembled airframe prior to fiberglassing. Yes, it is big. It is supported by Lynette Vatsaas, my Chief of Staff and Director of Procurement. This is the closest she has ever been to one of my rockets.

The forward and aft sections are the identical shape - one end gets fins and a motor mount, the other end gets a nose cone and avionics. Yes, I'm referring to the rocket, not my wife.

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The aft section of airframe installed on the high-speed sanding lathe after the two layers of fiberglass have been applied and the rough sanding is complete. The color is red because I have applied Bondo Spot Putty (note that I avoided the area where the fin fillets will go). The foward section stands behind the lathe. The sanding fixure is on the ground.

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Using a Dremel to cut the fine slots. I had already drilled the end points with a 3/4-inch bit.

It won't be obvious in any of the photos, but the fins will be canted just slightly to induce a clockwise spin. Because of the shape of the airframe, it will be virtually impossible to detect if the nose is out of alignment with the thrust. Any misalignment will be compensated by the spin stabilization.

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I couldn't resist the temptation to set up the Zephyr in my front yard after I dry fit all the fins. I almost caused an accident or two on my sleepy little street as people drove by were fixated on this monster.

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I added myself in the photo for a sense of scale.

I stand 6' 6".

In my dreams.

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The motor tube. It is a Public Missile 4-inch phenolic tube, 48 inches long. The rings are 1/2-inch 7-ply baltic birch. The additional rings give more adhesion surface. The two front rings are epoxied in first, and the aft ring will be left off until the fins are fully mounted.

Click photo for larger image

A view of the Paint Booth (special thanks to Billy Dahlberg for his help applying the paint). The rocket will be in these same three pieces when it comes down under chutes. Let's hope its in the same three pieces when I drive it home from the range.

The cost of paint alone is enough to convince me that it will be a long, long time before I build a rocket this big again.

Billy Dahlberg trusted me with his camera just long enough for me to snap this picture. Billy has been incredibly supportive of this project and has offered help - or just moral support - throughout the process.

It's unfortunate that the shadow from Billy's hat covers his face, but in all the time I've known Billy I think I've only seen him without a hat once. So he wouldn't be recognizable without the hat, either.

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