FMA DIRECT: FS8 Co-Pilot Receiver

Model Airplane News, Jul 2004 by Welsh, Joe

A new-generation flight-stability system with fail-safe!

DURING RC FLIGHT TRAINING, whenever student pilots lose control of their models, they have always had to rely on their instructors to save the day. Whatever the cause, it's often very difficult for a new pilot to figure out how to right his model in time to avoid an unintentional "landing." FMA Direct recognized the need for a flight-stabilization system to help make learning easier, and it introduced the addon "Co-Pilot" system that provided elevator and aileron control corrections (see our review in the june 2002 issue of Model Airplane News).

The new FS8 Co-Pilot system is a huge leap forward, as it combines an 8-channel, programmable, fail-safe FM receiver on one printed-circuit board. Because the Co-Pilot works with all 8 channels, it can stabilize flight in a variety of ways.

Like the original Co-Pilot, the FS8 allows a student pilot to simply release the transmitter's control sticks and let the system bring the plane back to straight and level flight. A host of other features makes it useful for experienced modelers as well. For this review, I installed the FS8 with an optional vertical sensor in a Hornet trainer ARF.

INSTALLATION

The FS8 consists of a pitch/roll sensor, a vertical sensor and a special receiver with connections for 8 servos and the infrared sensor module leads. I attached the pitch/roll sensor to the plane's belly, but you can install it anywhere, as long as it isn't in the exhaust stream and it has a clear "view" of the horizon on all sides. If you install it on a wing, you may have to disconnect it from the receiver when you remove the wing to transport your model. I installed the vertical sensor on one side of the fuselage; it has a clear "view" of the sky and the ground. The CoPilot comes with a small module that must be accessible because it has two buttons and an LED light that are used for calibration. I mounted it on the left side of the fuselage so it wouldn't be sprayed with exhaust oil.

After you've mounted the sensors, you must calibrate the Co-Pilot each time it's installed on a new plane. Place one or two cups of hot water near the sensors to "teach" the Co-Pilot the orientation of the mounted sensors. The Co-Pilot has one feature that you would typically find only on a more expensive PCM receiver: once it's calibrated, you may program the fail-safe positions for each channel. Thanks to the feedback given by the FS8 at each step along the way, the calibration process is fast and easy.

The manual recommends that you use the flight-stabilization feature as a failsafe preset, but it does not explain why. An advanced pilot doing aerobatics would prefer to fly with the flight stabilization turned off so that he has complete control over the plane. If the plane loses radio contact for any reason, the flight stabilization turns itself on to stabilize the model, and the servo fail-safe presets then take over. Keep in mind that you can only program the flight stabilization to turn itself on if your transmitter has at least 5 channels. There isn't any guarantee that your plane won't be damaged during a fail-safe-activated landing, but a radio-signal loss usually means your plane will be lost to a crash.

FEATURES

In addition to the flight-stabilization and fail-safe features, the FS8 receiver has other features that make it stand out. When you turn on the system (with the transmitter off) before you fly, it will check your channel for interference and will alert you if it detects any. It will also tell you the battery voltage within 1/10 volt. Once the plane is airborne, the CoPilot uses "Digital Signature Recognition" to distinguish between random interference and your valid transmitter signal; this helps to eliminate servo jitter. If it briefly receives a bad signal-it checks 50 times per second-it tells the servos to stay where they are until the signal clears up. If a bad signal lasts for more than 1 second, the FS8 engages the fail-safe mode. It then returns the plane to straight and level flight and moves all the servos to their programmed positions until it receives a good transmitter signal again. After you've landed your plane, the FS8 will display the number of times it entered fail-safe and how many bad signals (interference) it encountered while it was turned on. In my opinion, the FSS's ability to deal with radio interference is among its most impressive features.

Even in adverse weather, the system's ability to recover a plane and return it to a straight and level attitude works very well. It uses infrared detectors to "see" the horizon and to keep the plane flying parallel with it. The FS8 Co-Pilot also works with helicopters and any other airplane-control configuration, such as dual aileron servos, V-tails and flying wings.

PC READY

The FS8 comes with computer software that allows you to read additional flight information such as the battery's lowest voltage during the flight and the real-time transmitter-signal strength "seen" by the receiver throughout the flight.