Brief:
The Double Helix is another new twist on the monocopter (pun intended)--it has two wings and flies on two motors. In fact, it's more or less two 13mm Helix Monocopters stuck end to end. Technically, it's not a monocopter but a bi-copter.

Construction:
The parts list:

• Two 1/16" Basswood sheets
• One 24mm tube
• Two BT-5 motor mounts
• Two ¼" dowels
• ¼" launch lug

This build is exactly like that of the 13mm Helix Monocopter, there's just a little more of it. It only requires Elmer's Glue All and an X-Acto knife with a new #11 blade. Instead of repeating myself, I'll refer the reader to that review.

Finishing:
I have generally just been giving my monocopters a clear coat, but on this one I decided to paint one wing day-glo red and the opposing wing day-glo yellow. The body is still just clearcoated.

Construction Rating: 5 out of 5

Flight:
You form thrust rings with masking tape and friction fit the motors so they won't fall out. The motors should be oriented with their nozzles down. As with a Art's standard monocopters, you need a sturdy pad with a short ¼" rod (1" or so). Art provides plans for a suitable monocopter pad in the instructions. You will also need a clip-whip or a controller capable of firing two channels simultaneously since there is no way to twist those igniter wires together.

I flew the kit on two A3-4Ts ignited with a clip whip. It flew very nicely and went higher than its single-motored counterpart.

Recovery:
Unlike most of Art's monocopters, this model continues to spin until touchdown.

Flight Rating: 5 out of 5

Summary:
Like the standard Helix, this kit is easy and quick to build. When I first got this kit, I wasn't sure I'd like the clustering. However, the flight changed my mind. I liked the performance and the auto-rotating recovery.

Overall Rating: 5 out of 5

Brief:
The Double Helix is a great variation on the simple monocopter design from Art Applewhite. It is extremely simple to build and goes together quickly. It's also even more fun to fly than the Helix.

I was lucky enough to get to watch the flights of the prototypes as Art was developing this line and now it seems like he is the source of a monocopter renaissance. It's a lot of fun.

Construction:
The components for this kit consist of a pre-marked body tube, 2 motor tubes, a 1/4" launch lug, 2 balance beams, and 2 basswood wings. Also included are thorough instructions on building the rocket and instructions for a simple launching pad. This one is not meant for an Estes setup.

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.

After all the holes are cut out, the various pieces need to be test fitted into the BT. These include the launch lug, the motor tubes, and the balance beam. The wings wait until later. Pay attention to the instructions to get the balance beams oriented correctly. I built this one after doing a 13mm Helix and the balance beam in this case is not symmetrical.

When the pieces are in, they need to be adjusted for symmetry; all of the pieces need to be centered. With that done, a fillet of white glue is applied inside the BT to the visible parts of the intersections with the motor tube. With that done, all of the protrusions can be filleted with white glue on the outside.

The last items to be installed are the wing. These are made from a precut pieces of basswood. You can round the edges if you like but I did not. I slipped them into the marked ends of the BT. They will slightly deform the tube but that is expected and explained in the directions.

Alignment is not a problem. A filled triangle marks the point on the BT which should be aligned with the center of each side of the wing. Then it is just a matter of making sure it is sitting perpendicular, something aided by having its end sit flush on the motor tube. The wing is then glued into place with white glue. Repeat for the other side.

Finishing:
The instruction recommend a couple of light coats of sealer or a light coat of paint. I elected to go the paint route and chose red. I gave it just one good coat, the instruction warn against using too much and throwing off the balance.

Construction Rating: 4 out of 5

Flight and Recovery:
This was my first foray into monocopters (or bicopters). I used it at part of a demonstration for a kids event at the local museum and, as such, only got to launch it once. We had an extremely small launch area and I was prepared to consider myself lucky to retrieve any rocket. As such, I elected to use a pair of 1/2A3-2Ts. It didn't go all that high but it certainly got the kids attention. They loved it.

I look forward to flying it in the future on A3-4s.

Flight Rating: 5 out of 5

Summary:
This one is fun, easy, different, and an attention getter...especially from kids.

Overall Rating: 4 ½ out of 5