Model Forum / Radio Controlled / Air Models / June 2004

Unless you fly in downtown LA, I see no reason for the $$$ of PCM.  

True, PCM has failsafe, but that sometimes crashes your plane.  A plane can fly
through intermittent interference most times.  A PCM detects interference and
locks the controls.  This is good, unless you're in a vertical dive at the
time.  After the interference is gone, it takes a couple of seconds to return
control to the TX.  That might be a couple of seconds too long.

I've flown PPM over 15 years, and never lost a plane to interference.
Dr.1 Driver
"There's a Hun in the sun!"

PCM

Do a search using those terms on www.rcgroups.com and you'll get a ton of
opinions. Everything that can be said about the subject HAS been said about
the subject over there so there's no reason to start the argument all over
again here.

MJC

Len,

This will open a big can of worms, similar to the famed "downwind turn
theory".....

After a ho' buncha years in the sport, my opinion is there ain't a whole
lotta difference.

Both are FM transmission and subject to the same types of interference.  PCM
has a failsafe position you may assign to servos, but UNLESS the
interference disabling the receptionsubsides in time, the best PCM will do
over PPM is give you a few more seconds to get the broom out......

Cheers,

Bill

That is sort of like asking "Is you a Found On The Roadside Dead" man or
Chevy dude?  They both have their place and both have good and bad things
that can be said about them.  You pay your money, take your chances.

The PCM stuff is somewhat more expensive and SOME claim not really good on
gasoline powered birds.  As others have suggested, do some reading.

I doubt it........not here.

yep, here we go again.   And you will not receive an answer that will help
you.  I promise.

How long is that proverbial piece of string? You need to understand
the pros and cons of both to decide which is best suited to your
particular purpose.

As for meaningful answers. Unless you're trolling you'll largely
receive the same sort of uselessly emotive answers one does when
asking "Which is better":
(a) 4 stroke or 2 stroke?;
(b) castor or synthetic?;
(c) mode 1 or mode 2?;

RPM.

Neither. Both can me made to work well, and both can be implmented in a
shoddy way.

Which is better - V8 pushrod or turbo charged 4 cylinder with overhead cam?

Last summer I mounted a digital camera on my LT-40 with Hitec PPM and took
to the air.  After flying about 500 feet  from the strip I gave it left
stick to bring it back but the plane took 30 seconds to complete its 180
i.e. I had to hold full left stick for 30 seconds to make the turn.  As it
turned out the camera was generating noise on the receiver's power line and
the control surfaces where flapping like a galloping ghost system as soon as
the ship put a few hundred feet between it and the transmitter.  Just like a
galloping ghost system the flapping control surfaces averaged their flap in
one direction or the other depending on stick position.  This allowed me to
get the ship back to the strip safely (and fix the camera problem) but I
wonder if it was a PCM system would the controls have locked out and cause
my ship to sail off to uncharted waters?

Prop Flipper