So I upgraded my venerable Raptor 30 v1 to a Raptor 46 (approximately a six-pound helicopter with a five-foot rotor span). It has some issues with the engine when I tried to fly it recently at the field, so I took it home and fixed a few things here and there. It turns out I’d lost the two screws holding in the carburetor on my OS .46FX-H; I pillaged another set from my similar aircraft motor. I bought a brand-new high-performance muffler, got it attached, and started running it up and checking things out.
I was out in my back yard doing a few test hops, getting the mix just right so that I had good head speed, pitch-pumping to listen to the engine and hear where it bogged, you know the drill. I had it just about dialed in. Second tank of fuel, I landed, adjust my throttle curve to get my new motor running at the right RPM, stood back, and applied a little collective. It got about two feet above the ground, right where I wanted it, so I backed off just a tad… and it kept rising.
I jammed throttle hold. No response. Total radio lockout. Zero control. The helicopter looked for all intents like it was going to fly to the moon. It described a gentle arc at probably forty to fifty miles an hour, sailed right over my house, then slammed upside-down into my front yard, ricocheted into the air on a bounce that went for fifty-four horizontal feet, landed on its skids, and proceeded to spin madly on until the motor quit.
Well, all in a day’s work, right? Expensive lesson in radio lockout, but it could have been worse.
Much worse.
There were eight children playing near my front yard. Four of them were mine. This helicopter, luckily, missed all the kids and the four adults doing yard work to slam into my yard and flip end-over-end out into the cul-de-sac.
If it had struck any person on its way toward beating itself to death, I’d have been devastated. I really like my neighbors. I really love my children and my wife. This big beast could have killed any one of them a few minutes ago.
Yet I was following AMA safety guidelines. I was over 100 feet from my house, and over 200 feet from the eventual point of impact. I had kicked my kids out of the acreage behind my house, counting on distance and objects to limit the possibility of damage to anybody other than me. I’d counted on a lot of things… but not a radio lockout sending the heli sailing in a rainbow arc toward family members and neighbors.
Upon further investigation, I think I found the cause of the lockout. I have a bad cell in my NiCD Rx pack, which seemed to hold a good surface charge, but dropped voltage under load. I believe the voltage hit the magic “don’t run below 4.5v” mark for my Spektrum receiver, rendering the receiver and all servos inoperable while it spent five seconds reconnecting.
I should have cycled the pack.
I almost hit someone because I didn’t cycle my pack.
I feel like crap.