Art Applewhite Rockets - Delta Flying Saucer 38mm (18")
Contributed by Dick Stafford  Brief: This rocket is a huge, 18" diameter, Level 2 capable version of Art's Delta saucer. It is built primarily from Gatorboard® and includes both 38mm and 54mm motor adapters. Construction:
 54mm and 38mm Motor Adaptors parts list:
Materials and tools required: utility knife, X-Acto knife with new blade, spatula or other spreading tool, Elmer's Glue-All®, Easy release masking tape (the blue kind), sandpaper, slow setting epoxy, and Devcon 5 minute Epoxy.
You first prepare the top shroud by wrapping it around and connecting the seams with 5-minute epoxy and the supplied fiberboard strip. Once dry, you sand the hole to fit the 3" host body tube. The bottom is prepared similarly.
In short, you glue the mount to the top, coat the inside of the top with slow setting epoxy, attach the center to the top, and finally the bottom to the center. In this beta version, the main trick was to align the holes for the launch rod. In the production model, a ¼" launch lug is glued to the inside of the 3" host tube, thus avoiding having to cut additional holes in any of the components. The removable adapters slide past this lug. After the first flight, I retrofitted a 1/2" lug. The last step is to glass the top with the provided fiberglass sheet. This too is pre-marked. I won't go into the details here, but make sure you use slow setting epoxy as there is a lot of surface area to cover.
Finishing: Construction Rating: 4 out of 5 Flight:
I first flew the big Delta Saucer on an Ellis J228 at the 3rd Annual TRF Reunion at the Whitakers field in NC. The saucer tore off the pad with lots of smoke and noise. It was a fantastic flight. The second flight was at a NOVAAR launch. This was a very interesting flight. The J110 had a nice long 7 second burn. Because of the low average thrust and regressive thrust profile, the saucer arched over and was still under power after apogee.  Recovery: On the J110 flight, the saucer aerobraked down and continued to spew large amounts of smoke, causing some concern with the LCO. It landed in an outcrop of brush but that part of the field was damp and there was no risk of fire. The ensuing smoke cloud was described as a "mushroom cloud on the horizon". Cool! Still, I'd recommend the J228 over this motor. Flight Rating: 5 out of 5 Summary: Overall Rating: 4 out of 5
What You Can Do
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This build is very similar to the smaller delta
saucers, only bigger. The top and bottom shrouds were made from
pre-marked Gatorflex® and the center plate was made from the
thicker and more dense Gatorboard® piece. These materials are
both multi-layer laminates of dense polystyrene foam, laminated with plastic
and paper. The Gatorboard® is laminated on both sides while the
Gatorflex® is laminated on only one side, allowing it to be
flexible. Cutting these components was much harder than standard foamboard, so
new blades, patience, and good work surface are musts. Unfortunately, the
Gatorflex® is no longer available, so in the production model,
the top and bottom shrouds are made from standard foamboard. To make it
flexible, you make numerous cuts using a provided tool, which holds a
hobby-knife blade. Minus this cutting, the rest of the construction should be
almost identical.
The center plate really takes some effort and should
be cut in short sections. As with the smaller deltas, the edge is beveled. I
didn't have the recommended knife so I used a very sharp kitchen knife, which
seemed to work quite well.
For both size motor mounts, you cut the thin fins
from the basswood using the provided pattern, glue them to the tube, and
install the thrust ring. On the 38mm mount, I used wood glue and added epoxy
fillets. On the 54mm mount, I used only epoxy.
