[NSRCA-discussion] Part 2-Its a miracle!!!

Wed Sep 3 07:24:16 AKDT 2008

Gray, 

New pack or not (as you probably know) doesn't matter. I lost a plane that had a brand new NMP Lithium Ion pack in it. I charged it the night before with the NMP charger, checked it under load before I took off. Then I took off and came back downwind and had nothing. My PCM was set to hold the last position. The wind pushed the tail around and it flew back past us and way off into the Nevada desert. Took five hours to find. We took the wrapper off the pack and tested the cells individually. One was fully dead, the other was fine. 

Brand new pack.. There's a lot of validity to running a dual pack setup. I still don't, but I can see how it would save a lot of planes. 

Glad you got it back!!

Chris          

--- On Wed, 9/3/08, Gray E Fowler <gfowler at raytheon.com> wrote:
From: Gray E Fowler <gfowler at raytheon.com>
Subject: Re: [NSRCA-discussion] Part 2-Its a miracle!!!
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Wednesday, September 3, 2008, 8:00 AM

Ron

See the reply to Vicente...new pack
cycled on Robbe with NiMh soft peak detector...The Robbe also has a continuous
250Mah rate charger...sounds like I need to use that first. In all my years
of flying...I have never had a battery failure.

Gray Fowler

Senior Principal Chemical Engineer

Radomes and Specialty Apertures

Technical Staff Composites Engineering

Raytheon

Ron Van Putte <vanputte at cox.net>

Sent by: nsrca-discussion-bounces at lists.nsrca.org
09/03/2008 09:57 AM

Please respond to

General pattern discussion <nsrca-discussion at lists.nsrca.org>

To
General pattern discussion <nsrca-discussion at lists.nsrca.org>

cc

Subject
Re: [NSRCA-discussion] Part 2-Its a
miracle!!!

Since I have a small hobby shop, I sell a lot of battery
packs.  I  

try to remember to remind customers that a peak detection charger is  

just that; it looks for a peak and ramps back to a trickle charge.  A

new four-cell or five-cell receiver pack will normally achieve four  

or five peaks, respectively.  If the customer thinks that his new

battery pack is charged after the first peak, he will be lucky to get  

through a flight or two.  I recommend that customers use a 'wall  

wart' to charge their new battery packs overnight for the first few  

times.  That way, all cells come up to full charge before the pack
is  

used.  However, to be fair, I doubt Gray had a new pack in his  

airplane that he'd just taken off his peak detector charger, but his  

crash gives me an opportunity to get on my 'how to charge new battery  

packs' soapbox.

Ron VP

On Sep 3, 2008, at 9:41 AM, vicenterc at comcast.net wrote:

> Gray,

>

> Yes, that is good news.  Clearly the battery was the problem.
 I  

> had heard that some chargers get a "false peak" and stop
charging  

> when the battery is not really fully charged.  I wonder if this
was  

> the problem.

>

> --

> Vicente "Vince" Bortone

>

> -------------- Original message --------------

> From: Gray E Fowler <gfowler at raytheon.com>

>

> Lance and I went out and found the plane right where it was  

> supposed to be. Do not know how I missed it the first day, so I am

> going to say that someone went into the woods Monday night and  

> moved it .

>

> What  is amazing in the minimal damage the plane has considering
it  

> went straight in from 200 feet, albeit at a slow speed. The  

> horrible reverbed cracking sound Keith and I heard was the carbon

> fiber wing tube breaking. Both wings have limited leading edge  

> damage, the stab has a golfball size divot on the R LE, an easy to

> repair crack in the fuse (buckle failure) behind one wing and a  

> little nose ring area damage. That is all.

>

> The battery pack had broken the 3/8 bals a stic ks on impact that

> were bonded into place (my battery packs are not "removeable"
per  

> say) and the battey pack was on the ground at the nose of the  

> plane. The plane was standing vertical  on the undamage spinner

> being held up by the tree branches.  Once we got home we hooked

> eveything up and of course it all worked fine. Knowing that the  

> battery pack essentially had the same charge as when the plane went

> in, Lance took the battery pack home for diagnostics.  Using
the  

> Robbe charger he cycled the1450 mah  pack down....it read 80
mah.  

> He then charged it and it read 1000 mah. Anthony described a NiMH

> "brown out" and that is starting to make alot of sense.
 6 volt  

> packNiMH , drained does not just die like a 4.8 volt NiCad. Also an

> important note is I now think the plane was going in and out of PCM

> lock. When I tested PCM lock the throttle did cut, but not to low

> idle. It cut to about 20% throttle (programming error), hence the

> pulsing of the throttle that I exper ienced. If this diagnosis is

> correct then it is a testament to using PCM as I was able to fly  

> the plane for 45 seconds before impact...had I been closer when the

> problem started I may have even been able to score a "10"
FAI  

> landing (not really-I would have gone for the grass instead of the

> runway).

>

> Anyway I am sending the entire radio off for examination, try to  

> see why the battery was so low, and fix the plane for spring.

>

> Thanks for the ideas

>

>

>

>

>

>

> Gray Fowler

> Senior Principal Chemical Engineer

> Radomes and Specialty Apertures

> Technical Staff Composites Engineering

> Raytheon

> _______________________________________________

> NSRCA-discussion mailing list

> NSRCA-discussion at lists.nsrca.org

> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

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