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

[Gray E Fowler]

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
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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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