Any Given Sunday....

[iflyos]

You can go from this:



To this:




It happened today, at the Hobby Park Fun-Fly.


Everything was great....for the first 5 minutes of the flight. I had gotten up to altitude, and was enjoying some mild aerobatics, i.e. loops, rolls, nothing out of the ordinary. As I was lining up on the runway for a high speed low pass, the airplane stopped responding to control input. It went into failsafe. I had it set to maintain the last control inputs, and take the engine to idle.

My last control inputs were for a descending left hand turn, and that is what the airplane held. The engine went to idle, and the airplane continued to fly, until it met the first tree, and which point the departure from controlled flight escalated into a rapid descent through the trees until the ground was kind enough to stop the forward motion of the airframe.

After an in-depth investigation by my long time flying buddy, fellow amateur radio operator and best friend Robert Whitaker and myself, we were able to determine the cause of the problem: My transmitter had failed in a most unusual way. While it was still sending out RF, it had stopped sending the PWM data stream. In all my years of flying r/c models I have never once seen or heard of a failure of this sort. I have yet to put the radio on the bench and see what might have caused this problem, but I will be very interested to find out.


Anyway, I haven't had the heart to tear into the wreckage yet and see how bad the individual components (engine, radio receiver, servos, etc) might be damaged. At first glance, it appears all of that will be salvageable.

I will miss this one...While it wasn't huge (1/4) scale, it was a great flyer, and had provided me with lots of enjoyment.

The Irony is that out of all the swap meets, fun flys and fly-ins I have attended, I have never won anything...door prize, grand prize, nothing...till today. I won an Eflite Tribute FX 3d, lol...now I just gotta get a radio so I can fly it, or anything else in my fleet for that matter!!!

For those curious, Radio gear is a JR PCM 10SX, and the receiver is a JR R-790 Scan Select PCM.

I have verified RF output on the radio with my spectrum monitor, but don't see any PWM data when I look at the trainer cord output with a 'scope. The RF module checks ok in a 783, and I have a good range check with that radio.

Tim
AG4RZ

[SleepyC]

DARN sorry bro!
Patty is a fun plane.

Man at least you know the cause.
The one thing I really hate, when crashing, is not knowing why, and then questioning everything I own.

Best thing about RC airplanes... they are like Pringles potato chips,
Crunch all you want, they will make more!!

[thewrap]

Lots and lots of night mares.

[FireFighterFSFD]

I am betting youare using pcm. If you dont know this it might help, if you do then well this is the eay i understand it.
pcm send packets of information. Your fail safe has a preset number of packets it can loose or can recieve that is curupted before the fail safe kicks in. so in other words you are still tranmitting just not enough for the rx to exept. that is why when using ppm and you get hit the plane goes crazy and has a mind of its own. the failsafe in pcm must recieve the preset amout again before it comes out of failsafe. any way i hope i helped

[iflyos]

FireFighterFSFD,

You are correct, I am using PCM. However, I get no data stream regardless of the modulation mode I select. I have also checked the DSC/Trainer cord output with my ocssiliscope, and see no pulse width changes regardless of which channel is exercised.

I am getting rf out, according to my spectrum analyzer, and I am on frequency as well. I suspect something on the encoder has gone south, but until I can locate schematics for the radio, I won't know for sure.

Tim
AG4RZ