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

[Gray E Fowler]

Vicente

The Robbe charger has a setting for soft peak, which is to be used for 
NiMH. This is what I had. I cycled twice before using this new 
battery..what I remember was getting about 1300 Mah from this 1450 mah 
pack. I think there may be a "high drain" problem on the plane in 
addition.



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



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09/03/2008 09:42 AM
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Re: [NSRCA-discussion] Part 2-Its a miracle!!!






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 _______________________________________________
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