Barry,

Glitch protection.

Most people fly FM and don't have any problems. On some plane-engines-installations, you can get glitching from a variety of reasons. I recently test flew a Great Planes Pitts Special ARF with Zenoah G-62 power for a club member. It range checked OK, but right after take off I got a nose down hit. Once at altitude and out in front, the plane was OK. On landing at about 10 feet, I got the same blip down. I added power as people docked for cover and made a second approach, steeper and shorter with the plane more in front all the way and got it down.

Here are a few things I caught after landing that I probably should have before I flew it. His tail bracing wires and connectors were all metal, making a nice 1 meter long loop, about the same length as an antenna. His antenna ran right down the middle. He also has long leads from servos mounted in the tail, running parallel to, and close to the antenna. Finally, he had the ignition switch of the G-62 mounted next to the radio battery switch.

All of these can be fixed, and should be, but a PCM receiver would have ignored these minor glitches unless they were repetitive enough to cause the system to go into fail-safe. He had close to a thousand bucks in the air, so an additional $20-$50 for a good PCM receiver doesn't seem to be out of line and is good insurance. The little JR 770 PCM receivers I mostly fly are only $99.99 compared to the FM 700 at $79.99, so for 20 bucks, I put these on my "good" planes.

He is buying a PCM receiver and making the other fixes before we fly it again.