Wednesday, January 19, 2011

Review: Aardvark Rockets - AIM-4C Falcon

Aardvark Rockets was a manufacturer of low and mid-power rockets. Most of their products were scale but they also had a few sport fliers. Their mid-power line was acquired from Blackhawk R&D.

This post reviews their BT-50-based scale model of the AIM-4C Falcon that flies on 18mm motors and recovers on a streamer.


Construction:
This kit came with paper tubes and rings. The light BT-50 body tube appeared to be the same as Apogee's tubing - weight, color, etc. The scale nose cone was solid resin and two ballast washers were provided to keep the rocket stable. You cut the fins from two sheets of basswood and thin strips of balsa provided the fin details. The recovery system included a section of Kevlar® twine, a section of elastic, and a Mylar streamer.

The instructions were pretty good and were more than sufficient to build this kit. The most challenging parts of its construction were cutting the small front fins from the brittle basswood and aligning the three sets of fins (12 total). I was surprised when I saw calipers mentioned in the instructions. In order to get a true scale model, I suppose, they specify the fin placement to three decimal places! I rounded to the nearest 1/16".

The one problem with my kit was the quality of the basswood. Both pieces were warped and even though I tried to straighten them, the long fins re-warped after being exposed to the carpenter's glue (I used the waterproof variety). Because of the length of the middle set of fins and the way the fin stock was cut, the grain had to be placed perpendicular to the body tube. The long fins not only warped side to side, but the thin front ends also lifted away from the body tube. I managed to minimize the warping by soaking the ends in thin CA and pushing them back in place until they dried.  This was quite disappointing.

Finishing:
The basswood had quite a deep grain and required a lot of filling. I used Krylon primer and paints to approximate the color scheme identified in the instructions. The kit also included a full set of decals. These are *very* small and are not easy to cut out or manipulate.

Flight/Recovery:
The kit relied on friction fitting the motor. I should have scrounged a motor clip from the ol' parts bin, but thought of it too late. The recommended motors for this kit include: EST A8-3, B6-4, C6-5; APO C4-5, C10-7, D3-7, D10-7; AT D13-7.

Since the wind was fairly heavy, was blowing towards the trees, I decided to try a B6-4 for its first flight. The boost was good with some weather cocking but no sign of any wobble. The heavy plastic nose and weights did their job.

I was worried that the provided streamer would not slow the model enough, and my fears were well founded. I attached the streamer about 8" down from the nose, as recommended. The rocket came down nose cone first, with the body falling parallel to the ground. One of the rear fins came part way off, and the struts to the larger forward fins were destroyed. Easily repaired, but would probably happen again on the next flight. I will probably try a small chute instead. If I were to build another of these kits, I'd also add some paper or light fiberglass to strengthen the fin joints.

I subsequently flew Merlin on another B6-4, an A8-3, a C6-3, and a few C6-5's. The model few straight on the smaller motors but had a noticeable wobble on the C6's. I guess it was on the hairy edge of stability on the heavier motors. It broke a few more fins along the way and ended up on the top of a tall tree. RIP.