An introduction to SMALL MODELS

When you were a kid, did you ever dream of controlling your rubber-powered creations? And now, do you wish that you could build a plane in your living room while watching TV? Micro models take up less space than their larger counterparts, can be less expensive, take less time to build and can even be flown indoors! So what are you waiting for? Read on to see how easy it is to join the fun.

The field of micro RC models is rapidly developing, with new products and dealers showing up almost daily. For our purposes, "micro" refers to planes that weigh 2 ounces or less and that use radio and power systems that don't weigh more than 1 ounce combined. Another characteristic of the micro model is that it can use a single Li-poly cell for power. There are a variety of ready-to-fly models available from several dealers as well as quite a selection of kits designed for micro RC. Meanwhile, many modelers have had fine success converting small, rubber-band-powered models to micro RC. A good selection of plans is available for scratch-builders, ranging from simple stick fuselage models to more elaborate scale projects. A good start for plan projects are the Model Airplane News downloads, and many others are available from rcstore.com. Meanwhile, a number of modelers have successfully resized plans from older magazines at photocopy stores that have this capability.

Assuming you have selected the model, let's go over some of the equipment options available and look at a few features and compatibility.

RADIO GEAR

Receivers. Several types of receiver are currently being produced for the micro market. In general, all of them incorporate an electronic speed control (ESC) for small brushed motors. The ratings on these ESC circuits vary, so you need to make sure that the ESC can handle the motor selected. All of the current receivers are designed to operate from a single Li-poly cell (or equivalent voltage, if you're using Ni-Cd or NiMH batteries). At least one of the receivers, the Plantraco HXF900, operates on the 90OMHz frequency band, which eliminates all conflicts with equipment on lower frequencies (of course, you must use Plantraco's matching HFX900 transmitter). Several of the receivers are relatively wide band, and to function without interference, they require that adjacent channels not be in use. Others are narrowband and can operate safely in a crowded environment.

Most of the available receivers can drive actuators directly, while several have outputs that can drive servos. A few are capable of handling brushless motors' speed controls along with other features. The market is changing rapidly, so it pays to compare features and prices.

Actuators. In general, all of the actuators being produced for the micro market are designed along the same lines and operate in the same way. A coil is wired to a special driver in the receiver, in which a proportional voltage is generated depending on the transmitter-stick position. A magnet pivots within this coil and moves in response to the changing voltage. With the proper centering setup, the movement of the magnet is truly proportional to the transmitter stick. The primary difference in these actuators is their size. The smallest weigh only a few tenths of a gram and produce very light forces. Larger units can weigh several grams and operate the controls on larger or faster models.