[NSRCA-discussion] Ideas on radio beserkness-cause of crash??

Tue Sep 2 18:00:37 AKDT 2008

Gray,

What type and brand of servos were you using? I've had oscillation problems
when using JR digital servos and noted it on range checking. I swapped out
the JR servos with Airtronics digitals and the problem went away.

Did you by chance check the battery performance on the Rx pack with a
similar load that was being placed by the servos? I would be curious what
the discharge curve looked like after the crash if the Rx pack survived,
assuming there is data with a higher discharge rate closer to the servo
load.Looks like your planning on testing this.

I had an instance with a FM Rx where the plane just shot down to a 45 degree
during a level flight path. I was told by folks watching that I couldn't
have put that much stick in to make the plane react like that. When I landed
I found the antenna coiled up. After I fixed that it did it again. I then
switched to a PCM Rx with all Futaba digital servo's and never had another
problem in that plane.

It was also suggested that my crystal was cracked or bad on that Rx. When
Airtronics looked at it they could find anything wrong with the Tx or Rx and
replaced the crystal in the FM Rx anyway. I've used that Rx in sport planes
with no problems since.

Perhaps Mark Atwood may chime in.

I'm not sponsored and I'm not a Stylus expert, just curious. I fly the
Stylus Tx and the PCM Rx.

Larry Diamond

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Gray E Fowler
Sent: Tuesday, September 02, 2008 9:25 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Ideas on radio beserkness-cause of crash??

Hey Anthony 

Never set up that warning function. Several people have indicated a low
battery. Lance thinks fractured crystal...10 years old, stored in my garage
at 105F to 25F or so. Every battery failure I have seen (none were mine) the
radio flat out quit. Lance and I are going back out today, better equipped
(long pants-machetes!!!) If I find it I can re-test the battery..It tested
about 150 MAH of its rated capacity, but I do not have the tester drain the
crap out of the volatge. 
Man that plane flew good....9 lbs 15 oz...My skills are so deteriorated. 

Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineering
Raytheon 

Anthony Romano <anthonyr105 at hotmail.com> 
Sent by: nsrca-discussion-bounces at lists.nsrca.org 

09/02/2008 09:18 AM 

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Re: [NSRCA-discussion] Ideas on radio beserkness-cause of crash??

Hi Gray,
What a huge bummer. Did you have the low rx alarm function turned on? On the
Stylus that is a switchable function that will drop the throttle to alert
you to a low rx voltage. Now I am paranoid and have to go check mine.
Have heard of similiar "brown out" type of behavior with a Nimh rx battery
failure. Hope you can recover the aircraft. This time of year the growth in
most places can swallow anything.
Many solid flights for almost ten years on my Stylus but it is serviced
every winter.

Anthony

  _____  

To: NSRCA-discussion at lists.nsrca.org
From: gfowler at raytheon.com
Date: Tue, 2 Sep 2008 08:30:17 -0500
Subject: [NSRCA-discussion] Ideas on radio beserkness-cause of crash??

Guys 

Yesterday on my 4th flight of the day my PCM Stylus went nuts. PCM program
was set for idle throttle and about 5-6 clicks(trim wise) of up elevator-all
other surfaces neutral, and this was tested as such by turning off the
transmitter.  As I passed by center I noticed that I could not gain altitude
and the the throttle started going from idle to high...then ailerons started
oscillating small left-right deflections. I cut the throttle to the kill
position but the engine persisted up-down bursts. I was able to do a 180
degree turn with aileron coming back to center...never losing altitude, but
unable to change the altitude,elevator seemed unresponsive. As I passed by
center again I was losing more and more control. The plane flew over the
wooded area south of the field at about 200 feet high, I could not turn and
the ailerons rolled the plane upside down and it went straight down into the
trees. This whole episode last about 45 seconds. Cannot find the plane, and
remnants of Gustav are headed my way. 

Plane was new had about 10 flights on it. 

New battery..NiMH 5 cell pack -no regulator (ran 5 cell packs for years, no
regulator) 
Reciever-1999 Stylus PCM-never crashed, wrapped in foam 
New switch 
Transmitter-1999 Stylus, never been serviced, never had problems 

What would cause a PCM receiver to do such a thing? If I had and
intermittent signal, once the receiver did get a signal the only two
throttle signals should have been idle (PCM hold) and off (transmitter).  I
am going to send the transmitter in just to get checked. 

Thanks guys....

Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineering
Raytheon

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