Brief:
I was asked to test 2 oddrocs of similar design, differing only in their size. First I built the Corn Roc, a Styrofoam ear of Indian corn with an 18mm motor mount. Now I am trying its little sibling, the A-Corn, designed for 13mm power.

Construction:
Construction is very similar to that of the Corn Roc. It begins with making a slit in the motor tube for the engine hook. The hook is then placed and held down with tape. A thrust ring is inserted in the forward end and glued into place. Finally, the centering rings are slipped on and glued. I found the centering rings to be very tight and the hole was too small to allow my finger access with sandpaper. I finally filed away some of the thickness with a rat tailed file.

The fins are cut from sheet stock using a paper template printed in the directions. I cut the template out and traced the pattern onto the balsa. I then used an X-Acto to cut the fins out. I made no effort to keep them all the exactly the same figuring that minor differences would add to the character of the rocket.

The instructions recommend that the fins be left their natural balsa coloring to better blend with the look of this rocket. I liked the effect with the Corn Roc so decided to do the same with the A-Corn. The instructions also recommended that the fins be sealed with a clear coat to better protect them and to prevent warping. I used 3 coats of Rustoleum Crystal Clear on each side.

The recovery harness is based upon a thread of Kevlar® tied around the motor mount. I tied the Kevlar® in place and sealed it with a glue fillet. I also cut a small notch to accommodate the passage of the Kevlar®.

After the preceding step, I had to take a hiatus of almost a month before I could work on the rocket again. When I did, I began by inserting the motor mount into the BT. It was held in place with yellow glue.

I gave the glue on the motor mount/BT junction some time to dry and then inserted the BT into the Styrofoam ear of corn and placed it with 5 min epoxy. You have to make sure your Kevlar® thread comes out the other end. I used a pencil to do this.

The lines for the fin mounting are pre-marked on the corn. They are significantly short of the true length of the root edge but are easily lengthened. I used an X-Acto to cut a pair of parallel lines the width of the fin and then used the blade to gouge out the material. When done, the fin slid easily into place. I removed it and filled the trough with epoxy then re-inserted the fin. The other 3 fins were mounted likewise.

The launch lug was glued onto one fin. As directed by the instructions, it was not placed flush against the body but offset a bit for clearance. According to the instructions, I should have cut it in 2 and separated the halves a bit, but I did not do that.

Finishing:
The rocket needs no finishing.

Construction Rating: 4 out of 5

Flight:
The maiden flight of the A-Corn was on an Estes 1/2A3-2T, the smallest of the recommended motors. There was no problem in preparation beyond the engine hook being a little bit tight. The rocket took off straight, flew well, but as expected, not too high. The 2 second delay is a bit long but the chute popped and the rocket recovered safely. I was getting ready to try it on an A3-4T when I learned that the launch lug had popped and I would need to replace it before this one can fly again.

A video of the maiden flight can be seen here.

Recovery:
THe A-Corn comes with a chute from Hartle Engineering. I don't like plastic as a general rule, but if you are going the plastic route, Hartle is definitely the way to go.

Flight Rating: 4 out of 5

Summary:
This is a nice oddroc that performed well enough. It looks different and can be flown in a very small area.

Be sure to split the launch lug. That should reduce the torque and tendency for it to get twisted off.

Overall Rating: 4 out of 5