Today's Featured Review
Contributed by John Lee
Art Applewhite has recently been promoting a series of monocopters and, in the case of the Double Helix series,
bicopters. The 18mm version of the Double Helix is not as simple as its 13mm sibling but neither is it very difficult.
Mostly though, they are fun to watch and fly.
The kit comes with instructions, a piece of basswood that must be cut to dimension, 2 motor tubes, a 1/4" launch
lug and a pre-marked body tube. All materials were in good condition and of good quality.
The body tube, such as it is, is marked by the simple expedient of being wrapped by a sheet with all of the
relevant locations indicated by polygons of the appropriate size.
The first step in construction is to cut out the polygons on the body tube. This is done with an #11 X-Acto knife
and the blade needs to be a new one. The method recommended in the instructions and, which worked quite well, is to
push the blade in perpendicular along one line of a polygon, slowly push it in until the blade completely covers one
line segment, remove the blade, and repeat as needed until all sides are cut out.
The second step is to cut the basswood. A single strip is provided and from that both wings and the balance beam.
When done, there was a 4" x 3/4" strip left over that I am sure will come in handy one of these days.
The marks were made on the basswood and then a steel ruler was used to guide the X-Acto knife. The key to success is
to do it slowly, not pressing down to hard on any pass.
After the wings are cut out, they can only be forced into
the BT with some effort and flexing of the tube out of round. The instructions say to sand down either side for a
distance of about an inch. This was done by marking the limit on the basswood, laying a sheet of sandpaper out on the
edge of the work area, and working the fin back and forth.
The balance beam is supposed to have a 3/8" hole drilled in its center to accommodate the launch lug. I
decided to go ahead and install the beam so that I could use the holes in the BT to make sure the hole in the beam
would align. I had to do a little trimming to get it to fit but then it slid into place. I used a ruler to make sure
that each side extended the same distance.
Before gluing, I also test fit each of the other inserts except for the launch lug. When needed, I did a little
trimming and then put everything in place. When all was ready, I glued it with white glue and applied fillets.
the glue had dried, I got out the 3/8" drill bit and made the penetration through the balance beam. I then slipped
in the lug and glued that as well.
I can be a real dunce sometimes. Most of the Helices I have seen have been flown "nekkid" but I like a
little paint and the instruction indicate that is just fine as long as too much is not used. With that in mind, I put
the now dried "Black Death" in the booth and had at it with, what else, but black. About the time I snapped a
photo, I realized something was wrong but could not quite put my finger on it. I went back to my work desk to get
something done on another project and, voilá, there were the wings for the Double Helix starring at me: I
had forgotten to install them.
When the paint had dried enough for me to mess with the Helix and I had time, about 2 days, I took out the
wings and test fit them. They fit fine but putting them in place was much more difficult than it should have been
because of the paint, especially black paint.
The BT is marked with black triangles to serve as alignment marks. You insert the wing and make sure that the
edges lined up with the points. At least that is the way it is supposed to happen. With me, the black paint had
obliterated all traces of 3 of the 4 marks. The fourth line was barely visible.
I did remember that the wings are to be aligned at the same angle as the motor tubes. That meant that I was able
to get the wings right, I hope, but that I worked much harder at it than I needed to have done. Bad me.
The wings were glued in place and filleted. Everything was eyeballed into place. I hope its good enough and the
flight will tell.
With the wings in place, I set up the Helix and applied a second coat of paint to the body and the first coat to the
wings. I am going to leave it at that so as to not add too much weight.
out of 5
Flight and Recovery:
I only got one shot at flying this one the first time out. I chose to use a pair of C6-0s, prepped the rocket by
forming a thrust ring of masking tape around each motor, and loaded it up on the monocopter pad.
At ignition, it started to spin just like its supposed to and took off in a slow motion flight accompanied by a
buzzing sound. The C6s were a good choice because of the duration of the burn.
When they had burned out, the Double Helix slowed down its revolutions, came to a stop and then started spinning
in the opposite direction as it auto-rotated down. This was by far the best performance I have gotten out of any of the
out of 5
Cool rocket. Probably the best of the Applewhite Helices.
out of 5
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