MS Composit Hornet CP

Model Airplane News, Apr 2003 by Baron, Dave

A mini chopper with big-time performance

After flying a fixed-pitch Hornet helicopter for a few years, I yearned for a mini heli that would let me explore aerobatics and perhaps perform some 3D maneuvers. My dream was to have a machine that I could flip and tumble around in a gymnasium or outdoors in my yard. When I learned that MS Composit had upgraded the Hornet from fixed to collective pitch, I knew I had found what I'd been looking for! To simplify the heli, the control system uses cyclic/collective pitch mixing (CCPM)-a system in which three servos are mounted below the swashplate to drive it directly. You'll need to use a heli radio that has 120-degree CCPM mixing.

FIRST IMPRESSIONS

When I opened the box, I saw that all of the parts were sealed in numbered plastic bags by subassemblies. The kit also includes a detailed assembly manual, a Speed 300 6V motor, colorful decals and a canopy that's molded in halves. The parts count is slightly higher than that of the fixed-pitch version because more parts are required for the collective-pitch mechanism. The kit is available with either a standard canopy or the more scale-like Schweizer 300 canopy; mine had the Schweizer. The instruction manual is well written and contains numerous exploded diagrams and drawings. MS Composit's website provides numerous tips and detailed pictures that clarify any questions you might have. This is the first time I've seen this type of support, and it's very helpful. I highly recommend reviewing the website before you begin assembly.

ELECTRONICS REQUIRED

To get the Hornet airborne, you'll need four microservos, a micro piezo gyro, a 7-- or 8-cell, 720mAh NiMH battery and a 5A electronic speed control (ESC) with battery eliminator circuitry (BEC). As I've mentioned, you'll also need a heli radio with CCPM mixing. Here are some things to consider when choosing your equipment.

First is the ESC. Make sure that it can handle the loads imposed on it by the motor. When you use full collective, this means full power at the motor and lots of current draw. Also be sure that it can handle the battery sizes recommended. If your ESC has an adjustable low-voltage cutoff and you can't bypass it, consider using a different ESC. Nothing is more shocking than practicing unplanned autorotations!

Next is the BEC; it needs to be able to handle the four servos that are constantly working. Be sure to select servos that do not exceed the capacity of the BEC circuit.

CONSTRUCTION

The heli builds smoothly, and assembly requires only a few hand tools and thin CA. The ball links fit the balls better than any I have ever encountered; on many other hells, I have spent countless hours precisely fitting ball links to make them drag free. I'm glad this wasn't an issue with the Hornet.

Assembly is broken down into nine steps, and the exploded drawings can be removed from the manual for easy reference. I also recommend that you use a pin or a needle to precisely apply the CA. You don't want it to run where it doesn't belong.

Main frame. Begin with the main-frame assembly-the backbone of the heli. The parts that make up the frame are molded of a tough plastic and carbon fiber; assembly is quick, and the parts fit together very well. Just be sure to use the CA sparingly; a drop goes a long way.

Tail-rotor assembly. Many small parts are involved here, so take your time, and make sure that the parts have been assembled correctly before you apply any glue. The tail rotor is where I encountered the most problems-not so much with building it, but with its performance during the flight tests. I thought the tail rotor was sticky when I first flew the heli; the heli would continue to yaw in the direction of the last control input. I was perplexed, so I disassembled and reassembled the tail-- rotor assembly a few times and rechecked the pushrod and linkages. The problem persisted, however, so I decided to call the distributor, Avilus of Toronto, Canada. I spoke with Phil Anderson, who provided a lot of support to help find the cure. His first suggestion was to go to the CP upgrade pack, find the improved pitch slider and install it. The slider is a bearing with a housing around it that transfers the tail pushrod motion from the tail bellcrank to the blade grips of the tail rotor. Part of the problem is that the tail-- rotor output shaft that the slider rides on is a carbon rod, and not all fine carbon rod is perfectly round. This causes the slider to drag and contributes to the sticking problem.

I installed the new tail slider, and control of the tail improved, but it still hunted enough to confuse the gyro. I noticed that the slider assembly didn't fit in its housing very well. It is melted into place with a soldering-iron tip; both the original slider assembly and the upgraded slider that came with the CP package had slop between the housing and the bearing.

I have since installed another revised slider from MS Composit that consists of a two-piece brass sleeve that passes through the slider and rides on the tail-output shaft. The sleeves are tightened until the slop is gone, and it acts as its own bushing when it's spinning. This new slider has solved all of my problems with the tail; it's now powerful and solid, with no hunting or centering problems.