Building a Flying SpaceX Dragon

This is a brief tutorial for those who've never built a model rocket from scratch.

SpaceX made history on May 30, 2020 by being the first private company to launch a manned spacecraft. To commemorate this event, I decided to build a flying model of the Dragon spacecraft and Falcon booster.

There are currently no complete flying model kits of the Dragon, but there are 3D designs. After a considerable amount of work, I modified one of the designs to make it flyable. I'm not the only one to do this, either: Apogee Rockets has the files for those who wish to 3D print their own. For those without a 3D printer, I'm making a "barebones" kit available on eBay, here:

https://www.ebay.com/itm/303627247546

This instructable will walk you through the building process and what you need besides the kit.

In addition to the 3D printed parts in this kit, you will need:

• Estes BT-60 tubing (Inner Diameter: 1.595" Outer Diameter: 1.637"), 3.5" long.
• Estes BT-60 tubing (Inner Diameter: 1.595" Outer Diameter: 1.637"), 12.5" long.
• Estes BT-50 tubing (Inner Diameter: 0.950", Outer Diameter: 0.976"), 4" long, for motor mount.
• 2 ea. centering rings, .98" ID X 1.37" OD X 1/16" thick. Motor hook or motor retention of your choice.
• 4 ea. fins, 2" X 2" X 1/16", clear plastic (for scale appearance), balsa, or plywood.

• 18" parachute, shock cord, and shock cord mount.
• Epoxy (Recommended).

You'll have to make your own decals, if you want them. You can download the decals from this step. Print on decal or sticker paper at 100% scale.

You can get all the parts you need, except the centering rings, from Apogee Rockets, my favorite rocket shop. You'll have to make the centering rings from scratch out of mat board, cardboard, or thin plywood.

The exploded view shows the parts relationship. The 3D printed parts list:

• The spacecraft with "trunk" attached.

• The Falcon 9 booster top with the grid fins.

• The tail section with slots for through-the-wall fins.

• Cable tunnels for first and second stages.

• A 3/16" conformal launch lug with molded standoff.

A note on painting: The 3D printed parts have layer lines that can be seen and felt. To get a smooth surface for painting, I’ve had best results with “Automotive Filler Primer” (Available at Walmart and many other places) in a spray can. Sand, prime, sand, repeat, until you have a smooth finish. Final sand with 400 wet paper. I recommend doing all this sanding before assembly. The paper tubes will need much less prep than the printed parts.

As with most model rockets, the motor mount is constructed first. Install a standard motor hook on the motor mount tube (or the motor retainer of your choice). Remember you will need a motor thrust block if you do not use a motor hook. Cut two centering rings with an O.D. to fit inside the plastic tail part, and glue the centering rings to the motor mount tube, close to the ends where the rings will not block the fin slots. My rings are 3/8” and 2 7/8” from the rear of the motor tube.

Glue a shock cord to the upper end of the motor mount (or use the shock cord anchor of your choice), then dry-fit the motor mount, double-checking that the centering rings and motor hook are not blocking the fin slots. Epoxy the motor mount into the tail. I installed mine with the motor mount tube flush with the end of the tail.

This is a good time to dry-assemble one last time, with fins, parachute, and motor mount, and check that the CG (Balance point) is far enough forward. The empty CG should be no further aft than 15 ¼" from the nose tip. If the CG is too far aft, add some nose weight before going any further. I didn't need any nose weight, but your build might. Epoxy the main 12 ½” BT-60 body tube to the tail.

Install the Cable tunnel (The long skinny parts) on the main tube, lining it up with the stub tunnel on the tail section. There are two pieces; combine them to run the whole length of the tube. Snip off the excess at the top of the tube when dry. There is also a shorter cable tunnel for the upper tube. Match that to the stub on the upper end of the grid fin section. Super glue works very well for this part.

Epoxy the spacecraft to the 3 ½” tube and the grid fin section to the other end of the same tube. NOTE: The grid fins are at the bottom of this section! The rocket will separate at the joint between the grid fin section and the main tube. Epoxy a knotted loop of Kevlar into the grid fin section as a shock cord anchor. If using clear fins for a scale appearance, paint the model before attaching the fins so you don't have to mask them later.

When attaching the fins, install a new or spent motor in the motor mount to prevent the fins from crushing the motor mount tube, because you want to press them in firmly. Install the 3/16" launch lug on a 3/16 -1/4" standoff (or use the 3D printed lug) at the approximate CG of the rocket (about 4” below the top of the main tube), between all the fins. Make sure the launch rod will clear the fins!

Add the parachute and chute protector, attach the shock cord, and you're done!

The prototype flies very well on D12-3 and D12-5 motors. Can also be flown on 24mm Aerotech motors for more altitude.
I assume ZERO responsibility for poor assembly or bad flights. Build well, fly wisely!

Also, don’t leave your rocket in a hot car; the plastic may soften and distort.

Original design by Zastro, https://www.thingiverse.com/thing:1802512 heavily modified by me.

You can get the kit of 3D printed parts on eBay here:

https://www.ebay.com/itm/303627247546