Fail-safe settings for control surfaces

[Rick Kent]

I'd have to agree that a spin with throttle to off or idle, is the only
setting that makes sense. It's the only way to make the plane do a known,
predictable  maneuver without the benefit of the transmitter's guidance. I
see people arguing for straight and level all the time, but how will that
help if you're in a 90 degree dive or flying the part of a humpty bump or
something that temporarily aims the plane towards the pits? I'd much prefer
not to have to search hundreds of acres of land for a flyaway aircraft or
risk spectators. The spin is the only setting that accomplishes those goals,
IMHO.
Rick  
 
-------Original Message-------
 
From: discussion at nsrca.org
Date: Monday, May 16, 2005 04:21:31 PM
To: discussion at nsrca.org
Subject: Re: Fail-safe settings for control surfaces
 
Hi Larry
 
Having had a TX failure, I know from experience the utter helplessness that
a pilot feels when his plane is no longer in his control. It sucks big time
and I do not wish it on anyone. The most important thing is to ensure the
safety of  everyone around you as the plane is now simply a projectile on an
uncharted course. 
 
These are my thoughts on "Fail Safe" settings... no one else's.
 
First and foremost, I consider this a "failure setting" hence the title 
Fail" .... not some sort of "glitch-setting" setup to get my plane to
maintain a path of flight. If your looking for a "glitch safe" setting I don
t have any answers...sorry.
 
Now following the "Fail" part of your dilemma (i.e. your TX has failed for
some reason) comes the "Safe" part. This is setting up your controls to make
the airplane do a controlled "arrival" without 1) killing or injuring anyone
and 2) causing any property damage. Remember the plane is going in
regardless and, unless your on short final when the failure occurs (not
likely),  your going to probably lose the airframe.  The intent is to not
loose anything else.
 
Once you come to that realization, the set up is easy. I have a spin
programmed into mine. Not a fast one that we see in competition but a slower
 winding descent that will cause the aircraft to arrive somewhere within the
box (which is where I fly 98% of the time).  Slight right aileron, slight
right rudder & some up elevator with the throttle at Idle.  Will this save
my plane? No. Will it provide the most safety for everyone around? I believe
it will.
 
For those that have PCM RX/TX's and have no Fail Safe setup whatsoever then
your odds of failure equalling disaster are high (same as non PCM types in
fact).  For those with Fail Safe set to "steady state" with idle then your a
little better off as the plane will likely maintain a relatively steady path
until impact with whatever/whomever it hits.  Remember you have no control
at all.  And for those like myself with the spin setup, I have somewhat
better odds of containing the carnage as it's going in within the box. Last
time I checked most of the pattern boxes where devoid of obstacles
(cars/people etc)  
 
Now under some circumstances the "Spin" scenario I use may not give me a lot
of time but I would plan to do a couple things to get my plane back under
control. 1) Make sure the TX is "On" and you didn't adjust the trim's with
the "On" switch.... seen it done:-) 2) push/hold the antenna into the TX
(might be a contact or the antenna has twisted loose... seen it done.) 3)
Yell your frequency out loud as someone may have turned "on" accidentally.
(Or you forgot to tag up yourself and he's on legitimately ... seen it done.
)   
 
Remember PCM Fail Safe is not the be all and end all. You could find
yourself in equal trouble when the RX battery dies because you forgot to
charge/check the voltage or the RX fails. It just gives you an way to help
prevent possible disaster when the TX fails, nothing more.
 
These are my thoughts and I'll leave it to you and anyone else out there to
decide how they want to have their plane react when there is a hard TX
failure (not glitches). 
 
Safe building & flying,
 
Dave Reaville
NSRCA I-VP
Canada West District
NSRCA 3156
MAAC 56510 
http://members.shaw.ca/patternwestnews/   
 
----- Original Message ----- 
From: L Caldwell 
To: discussion at nsrca.org 
Sent: Monday, May 16, 2005 7:03 AM
Subject: Fail-safe settings for control surfaces


Hi All,

What is the general concensus for the best setting for the control 
surfaces on a pattern plane, and why.  I'm going to be put a PCM 
receiver in my plane, primarily for the throttle fail-safe, but I'm not 
sure what would be best for the control surfaces.

I would like to have the safety of the onlookers, other fliers, and 
field neighbors as the main priority, but still have a chance to recover 
the plane if it comes out of failsafe.

I've considered these options:

1) Low idle, controls at neutral but with a slight amount of up 
   elevator.  That might be a good way to see brief lockouts, but
the plane could travel a long way if it stayed locked at at high
altitude.

2) Last good signal doesn't seem like a good idea to me if it
stays locked out.  You could get anything there.

3) This seems safest for the crowd, but probably bad for the future of 
the plane.  Low idle or engine off, full spin entry on the 
controls.

Any better ideas?

Larry Caldwell
Brookland, Arkansas
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