Redundancy

[Dean Pappas]

Hi All,
Many moons ago, before digitals, I tried dual elevator servos and didn't like it one bit. I am going to re-try with digitals, soon. I expect success.
Later,

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Bob Pastorello
Sent: Monday, January 24, 2005 4:38 PM
To: discussion at nsrca.org
Subject: Re: Redundancy


Right on, Keith - I may have been one of those who USED to say that - and perhaps others....and I can offer two REALLY good reasons...
    1.  Transmitters in ages gone by could not "do" the mixing, atv'ng, expo, etc. needed.
    2.  Non-Digital servos just weren't available in a size to make it practical.
 
Nowadays, given if there is an option to use one or two, I go with two digitals EVERY time.

Bob Pastorello
NSRCA 199  AMA 46373
rcaerobob at cox.net
www.rcaerobats.net
 
 

----- Original Message ----- 
From: Keith  <mailto:tkeithb at comcast.net> Black 
To: discussion at nsrca.org 
Sent: Monday, January 24, 2005 3:31 PM
Subject: Re: Redundancy

Amen! Not to mention that the stab servos are REAL easy to setup.

When I was building my first pattern plane I asked about this and got some
negative feedback on the dual elevator servos. Reason given was due to the
halves not matching and servos wearing unequally. Well my experience is that
this hasn't been an issue at all and in fact it was easier to get them
perfect than with pull-pull.

I use the JR DS3421SA servos in my stab, they are excellent!

Keith Black


----- Original Message ----- 
From: "Ron Van Putte" < vanputte at cox.net>
To: < discussion at nsrca.org>
Sent: Monday, January 24, 2005 3:07 PM
Subject: Redundancy


> There's been a lot of discussion about using two battery packs to
> provide extra capacity and redundancy.  However, as Dean Pappas
> mentioned earlier, most battery packs fail shorted, so they still
> provide energy, albeit at reduced voltage and with limited current.
> However, I have seen many servos fail and their failure mode is usually
> "dead at neutral" or "dead hard over".  Neither of these modes of
> failure is particularly conducive to airplane well being.  Most of us
> use two aileron servos and having two aileron servos saved two
> different airplanes of mine.  One servo failed "dead at neutral" and
> the other "dead hard over".  The first was not a problem.  The second
> was a struggle, but I got it on the ground safely.  After the second
> servo failure on aileron, I started using dual elevator servos on all
> my airplanes.  I haven't had a servo fail on elevator yet, but, if one
> does, I'll have a fighting chance to get the airplane back on the
> ground safely.
>
> Ron Van Putte
>
>
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