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In those days a twin engine airplane couldn't maintain flight on just
one engine, in most cases. So, in his book, (We) Lindbergh stated that
twin engines "gave twice as much chance of an engine failure." The
only thing two engines did, was to insure that you had enough power to
make it to the crash scene.<br>
Bill Glaze<br>
<br>
Bob Pastorello wrote:<br>
<blockquote cite="mid00c601c5026e$25c67b70$5da26144@oemfu7ig3a7fro"
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<div><font face="Arial" size="2">Yeah, Tom, we're kinda back to why
Lindberg didn't choose the twin Bellanca... I think he said "twice as
many things to go wrong", or at least that's my clouded recollection of
the movie version...</font></div>
<div> </div>
<div>Bob Pastorello<br>
NSRCA 199 AMA 46373<br>
<a href="mailto:rcaerobob@cox.net">rcaerobob@cox.net</a><br>
<a href="http://www.rcaerobats.net">www.rcaerobats.net</a></div>
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<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">-----
Original Message ----- </div>
<div
style="background: rgb(228, 228, 228) none repeat scroll 0%; -moz-background-clip: initial; -moz-background-origin: initial; -moz-background-inline-policy: initial; font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>From:</b>
<a title="nsrca@shinymetalass.com"
href="mailto:nsrca@shinymetalass.com">Tom Simes</a> </div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>To:</b>
<a title="discussion@nsrca.org" href="mailto:discussion@nsrca.org">discussion@nsrca.org</a>
</div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Sent:</b>
Monday, January 24, 2005 4:28 PM</div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"><b>Subject:</b>
Re: any merit in running dual battery packs ?</div>
<div><br>
</div>
On Mon, 24 Jan 2005 14:45:32 -0500<br>
"Dean Pappas" <<a href="mailto:d.pappas@kodeos.com">d.pappas@kodeos.com</a>>
wrote:<br>
<br>
> LEDs have large voltage drops. Something more interesting would
have<br>
> to be done. You have to figure out what is most likely to fail. My<br>
> high-falutin' analysis, done ages ago, showed that switches and<br>
> connectors are the worst culprits. I use one battery withtwin
leads,<br>
> and cvarry the twin leads all the way to the RX. Of course, I don't<br>
> buy the cheapie batteries. Hello SR! Dean<br>
<br>
So I can see that your method likely reduces the probability of failure,<br>
but as far as I can see you still have no indication that a failure has<br>
occurred in the primary system until a failure occurs in the secondary<br>
system as well - although when the notification occurs it's a doozy!<br>
<br>
Checking Digikey it looks like even the high efficiency LEDs are<br>
still in the neighborhood of 2 V forward drop and the drop is fairly<br>
consistent across their operating current range (darn physics!). <br>
<br>
It looks like one might be able to use something in the TI TPS61010 thru<br>
TPS61016 family to drive the LED (although obviously at the cost of<br>
increased input current). Or what about using a dropping resistor and<br>
tapping the current flow downstream of the regulator with the lowest<br>
voltage setting? Should I crawl back in my hole with this? I'm just<br>
thinking that some kind of visual failure indicator would really be<br>
a beneficial addition to a two pack design.<br>
<br>
Of course that wouldn't show you that the backup pack had a failure<br>
while the primary pack was still operating... Although you could have<br>
an LED on both regulators and as long as the expected one was on...<br>
Vague memories of statistics class, MTBF calculations and the effect of<br>
adding components to a system are starting to crop up about now...<br>
<br>
Nevermind, straight back to my hole it is - now where did I put that<br>
tinfoil hat?<br>
<br>
<br>
Tom<br>
<br>
_____________________________________________________________________<br>
<br>
| , | Tom Simes<br>
---------(@)--------- AMA 230068<br>
--|-- NSRCA 3830<br>
' <a href="mailto:nsrca@shinymetalass.com">nsrca@shinymetalass.com</a><br>
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