What are the advantages of PCM with a heli

[clm]

Looking at getting a Raptor 50 v2 and a Futaba 9c.
My question is should I get the FUTJ88 with PCM receiver or save $100 and go with FUTJ86 which does not come with PCM receiver?

What are the advantages of PCM with a heli?


clm

[WillJames]

Get the PCM. Failsafe settings are enough to warrant the 100.00 on a heli. IMHO

What failsafe does is move your servos that have failsafe activated in the radio program to preset spots in the event of a radio problem.

[clm]

I do not understand.

What would a failsafe setting be for a heli?

If their is a goto hover setting, it would be worth $$$.

If you happen to be in a hover when something goes wrong with the radio, perhapes a failsafe might be acheved.

A'm I missing something?

[Greg McFadden]

failsafe doesn't necessarily save the heli, but when setup properly it will save people from having to flee from your full bore out of control heli. It will also minimize the damage when the heli hits the ground (sometimes)

However, if you set it up with a copilot (I can't help you through this unfortunatly, although I want to try it sometime, I haven't gotten around to it) you can set failsafe to turn the copilot on which will if gone properly (I think augusto did this last year sometime, I have long since lost the post on it) bring the heli into a stable hover. (or possibly a stable decending hover)

[capebob]

In addition to the above, PCM receivers are somewhat more interference resistant than PPM receivers. PPM transmitters send control and timing pulses by a simple shift of the transmitted frequency up (JR) or down (Futaba). Any interference that alters the frequency will be read by servos as a command to move. For instance when someone turns their transmitter on on your frequency it is most common for all your servos to slam to one extreme or the other rendering your aircraft totally out of control. In a PCM link the transmitter sends a discrete code to the receiver for each channel. All other signals are ignored. If the receiver is receiving a pure signal everything works normally. If the signal starts to degrade, as long as the pulse codes are received everything works normally. When the receiver fails to detect a valid code, and after a short delay, the receiver will command the servos to do one of two things. Depending on what the receiver has been programed to do (by the user) it will command each servo to either stay in the position it was in when it received its last valid signal (hold) or move to a preprogrammed position (fail safe). When this occurs it is called "lockout". If a valid signal is received after a lockout, system operation will return to normal. This doesn't mean that you won't lose control if someone turn on their transmitter while you are flying, but it does mean that your servos won't slam to one side and you will have at least a chance of getting the stupid #$%#@ to turn off his radio before you hit the ground. :arggg: Also, if you should happen to be doing a piro-flip and you get a lockout, well you probably get the picture. The most common setup is to have all servos hold and the throttle servo go to idle. I know, I know not everyone agrees with this.

An argument has been made by some, stupidly in my humble opinion, that PCM is dangerous because the aircraft under lockout doesn't slam immediately to the ground. There was a fatal accident in the U.K. a year or so ago when a plane under lockout flew a considerable distance and fatally injured a young child. It was noted that if the airplane had crashed immediately the accident would have been avoided. Perhaps, but there's no guarantee that a PPM plane losing a signal will crash immediately although I guess it's more likely that it would.

Hope this helps,
Bob