This is a cheap and easy-to-make rocket that flies on 54mm high power motors. There is no recovery and no electronics to prep or worry about. Simply insert motor and fly. This is a good rocket for higher-risk research motors, such as new formulations in 54mm or new grain configurations in that size. This rocket flies from a 1/2" rod. Feel free to name it anything you want. My son named this one "Cereal Bowl", which is what I've been putting on flight cards.

Please note that I didn't really take any measurements and kind of cut parts as things progressed. I did try to present measurements for this plan, but they may not always be 100% accurate.

Parts list

- 1/2" foam board (Elmer's, 20" x 30")
- 1/4" foam board (Elmer's, 20" x 30")
- 1/4" plywood
- 54mm phenolic motor mount tube (9 1/4" long)
- BT-20 body tube (9" 1/4" long)
- self-adhesive label paper
- fiberglass (4oz)

Start by making a mark 10" from both of the wider sides of a 1/2" foam board sheet. Connect the two marks with a line (a). This divides the board in a 20" x 20" section and a 10" x 20" section. Make a mark (on the 20" x 20" section), 5.86" away from each corner. Connect those marks to form the lines (b) of the octagon. Only 3 are shown in the images, you would make 4 lines total.

Cut on the lines (a & b) to create the octagon. You can do this with a sharp hobby knife, or saw. This will be the middle section of the rocket.

Cut out two 6" x 6" squares from the 1/2" foam board. Make a mark 1.76" from each corner. Connect the corners with a line and make a cut on the lines. This will give you two smaller octagons.

Draw lines on the octagons to connect opposing corners. This will mark the middle of each octagon. The smaller octagons will become the top and bottom surface of this rocket.

Next, make a hole in the middle of the 3 octagons. This should snugly fit the 54mm motor mount tube. You could do this with a sharp hobby knife. Use a compass to draw the circle to be cut out first. I used an adjustable hole cutter on a drill press instead.

Using the hole cutter was great for the smaller octagons. The largest one was too big to fit on the table. A hole was cut from a piece of plywood. This piece was then placed on the large octagon. The plywood circle that got cut out was used as a guide (line up middle of octagon with pilot hole). Some masking tape was used to hold everything in place.

The wooden disk was removed from the plywood sheet and a circle draw using the plywood cutout as a guide. Next, the circle was cut out with a hobby knife.

Time for the launch lug holes. These were drilled with a 3/4" bit. A spare section of 54mm MMT was used to line everything up. The small octagons were slid on it, along with a section of ply. This is the same section of ply shown above, cut to size. The (middle of the) hole was drilled roughly 1" away from the motor mount hole. In hind-sight, I drilled the hole in a bad spot. Don't drill it any of the lines that were used to find the middle of the octagon. Cut it right in the middle of two lines.

As before, the large octagon wouldn't fit on the drill press table, so everything was lined up on the large octagon and a circle drawn, through the existing hole in the smaller octagons. That circle was cut out with a hobby knife to form the launch lug hole.

A second piece of ply was cut out. These will be used to add strength to the rocket and to provide a surface to thrust against. You should now have the pieces shown on the right. One piece of ply was glued to each side of the large octagon, with the launch lug holes lined up. In hind-sight, it would have been smarter to cut the ply pieces in octagon shape, rather than rectangles/squares.

Cut out 8 pieces of 1/2" foam board, each 5" by 9 5/16". These pieces will from the inside support of the top octagon section. Test fit each piece and draw a line from where the support piece meets the top (smaller) octagon to the bottom outer corner. As you can see in the picture on the right, you will need to cut a slit to slide it over the plywood on the base. If the plywood were rectangular, all slits would have been the same size. As I didn't do this, each slit has to be custom fit/cut.

Cut on the line you drew on the top support pieces. You will also remove a slit on the top of each piece (1/4" deep) to fit the top octagon. I forgot to take pictures of this, see the next picture. That is for the bottom structure, but the general shape is the same. Once all 8 pieces are cut and fit nicely, glue everything together with wood glue.

A little thickened epoxy was used where the center octagon meets the plywood pieces and where the smaller octagon meets the motor mount tube. Glue fillets were created wherever foam board meets foam board.

For the bottom, similar supports where cut out, starting with a 6" by 2 1/2" rectangle.

Once all 8 pieces are cut and fit well, they are glued into place. Same as before, wood glue fillets on board to board bonds and some epoxy on foam/ply to motor mount joints. This forms the bottom structure of the saucer. All we need now is the side panels.

The measurements for the bottom side panels are shown on the panel itself in the image on the right. Note that the side panels (both top & bottom) are cut from the 1/4" foam board, not the 1/2" board. The top is 2 1/2" wide, the bottom is 5 1/4" wide and the side lines are 4 3/8" long. Basically, just get a ruler and take some measurements where the panel will go. Note that this does not need to be perfect, I had plenty of gaps.

Each side panel is then glued onto the bottom of this high power rocket.

The measurements for the top side panels are : top width 2 1/2", bottom width 8 1/2" and height 8 5/8". Again, these measurements may not be exact, take your own measurements, cut a single panel and test fit it.

Glue all 8 panels in place with wood glue. Again, don't worry if you don't get a perfect fit.

And here's why we didn't worry about gaps... simply put a strip of self-adhesive over all joints. This will hide any gaps. This was not done merely for cosmetic purposes. When fiberglassing the rocket, epoxy might seep into the gaps and build up there. That's just a waste of weight. Closing the gaps will avoid that and will make applying fiberglass easier.

Cut out strips of fiberglass next. First, a template was cut from paper. Simply put paper on the side of a panel and cut it so it overlaps the to adjoining panels slightly. Also make sure it goes over the top to the motor mount and over the bottom to the bottom side panels.

Here is the top, all glassed. I made a frame to put it in (wrapped in seran wrap). This was done to keep the wrap around the bottom of the octagon in place. This is entirely optional, just make sure the fiberglass stays in place. To complete the rocket, apply the fiberglass to the bottom section and let cure.

The rocket wobbles a bit at takeoff in the first video. This is due to a combination of the launch rod being at an angle and my standoff (PVC pipe) being too long.

Video : Octagon J310 - Octagon K300 - 30" Octagon L700 - 30" K850 Sparky - 35" M1000

The 30" version of this octagon design has a 75mm motor mount. The 35" version has a 98mm motor mount.