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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Ihncheol,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I don’t know if the 3400G and the
3517 are truly the same servo. The 3517 is listed for airplane and heli use. I
don’t see the 3400G currently listed, and I don’t recall what it
was recommended for. My only reservation about using the 3400G would be the “G”
designation, which is for gyro. The G servos often have higher gain settings (good
for heli tailrotors and gyros) which when used on airplanes are great for a
very accurate and aggressive center, but can contribute to jittering. There
are several JR servos that have identical dimensions, weight, speed, and torque,
but different model numbers and different narrative applications. The majority
of the time, it is the exact same servo, but the gain is tailored to a specific
application.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><br>
Dave<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b><st1:place w:st="on"><st1:PlaceName w:st="on">Ihncheol</st1:PlaceName>
<st1:PlaceType w:st="on">Park</st1:PlaceType></st1:place><br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, January 07, 2009
2:58 PM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">General
pattern discussion</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [NSRCA-discussion] JR
Servos of choice these days</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Dave,<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Isn't the JRPS3517 a relabeled JRPS3400G ??<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Identical specifications except 3400 never came out with MG.<o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>I'm going to try 3400Gs on Elevators since they show same spec
with 3517 unless Horizon doesn't recommand it? <o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Ihncheol<o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Dave
<DaveL322@comcast.net><br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">General
pattern discussion</st1:PersonName> <nsrca-discussion@lists.nsrca.org><br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, January 7, 2009
12:10:45 PM<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [NSRCA-discussion] JR
Servos of choice these days<br>
</span></font><font size=2 face=Arial><span style='font-size:10.0pt;font-family:
Arial'><br>
Ok....here goes...<br>
<br>
My "standard" servo package for many years has been: <br>
9411sa on ailerons <br>
8411sa on rudder <br>
8417sa on elevator <br>
3421sa on throttle (better yet, Castle 85 HV <G>) <br>
<br>
As FYI for those not familiar with JR servo nomenclature - <br>
- DS prefix indicates digital. <br>
- MG indicates metal gear. <br>
- SA indicates metal and nylon geartrain (generally metal pinion on servo<br>
motor, with metal output shaft, and 2 or 3 intermediate gears are nylon). <br>
- 4 digit number indicates coreless motor. <br>
- 3 digit number indicated cored motor (3 or 5 pole). <br>
- 1st number indicates general case size (ie, 8411 and 821 share same<br>
mounting pattern). <br>
There are some exceptions, but the above is applicable to most current and<br>
past JR servos. <br>
<br>
Speed and torque generally increase proportionately to increased voltage,<br>
and I have always run relatively high voltage to improve servo performance.<br>
In my glow days, I used 5 cell unregulated Nicd or Nimh to power the<br>
receiver and servos, and "bump" charged every couple flights to keep
the<br>
battery voltage high. When I converted to electric powerplants, I started<br>
using (in parallel) 2 sets of TP 2s1p480 lipos regulated to 6.53 volts<br>
through Tech-Aero Vregs. <br>
<br>
8417 - is only available as a MG servo. The 8417sa is an 8417 that has
had<br>
the 3 intermediate metal gears replaced with the nylon gears from an 8411sa<br>
or 8231 (buy the 8231 gearset, it is all nylon, and costs less). 8231
gear<br>
ratio is slightly slower than the 8417, so an 8417sa at 6.5 volt is about<br>
0.09 sec and 130 oz/in torque. <br>
<br>
9411 - I don't know of a midsize JR servo better suited for ailerons (save<br>
running 6.5 volts instead of 6 volts, which is good for about 0.01 sec on<br>
that servo). <br>
<br>
3421 - I've used this servo a lot (including pairs mounted horizontally on<br>
the engine mount for the Webra 160MC), but never in pairs on elevator as I<br>
prefer a single servo. However, the 3421sa is a good choice (in pairs)
for<br>
elevator @ .015 sec and 75 oz/in torque @ 6v. The 3517 is another option
-<br>
slightly faster (and less torque) - 0.09 sec and 51 oz/in torque @ 6v.<br>
<br>
8411 - this servo is close to 200 oz/in @ 6.5v. Several years ago, I ran<br>
the 8411sa and 8611 back to back in my EMC, and I couldn't tell the<br>
difference between them in flight, so I've stayed with the 8411 as it is<br>
lighter (and the rudder size has not increased on the majority of planes<br>
since that time - but the fuses have!). <br>
<br>
Brief sidenote about metal / nylon gears. Metal gears are for strength<br>
(especially when space is at a premium), but are typically manufactured with<br>
small clearances (slop) to avoid binding. Nylon gears can have zero<br>
clearance without binding (gears flex instead) have better wear properties.<br>
I find the nylon gears ever so slightly more accurate for very fine control<br>
inputs ("leaning" on the stick, without actually moving the stick).<br>
However, the nylon stuff will deflect ever so slightly under load, whereas<br>
the metal gears do not flex under, so the "personality" of the servos
at<br>
center and just off center can be slightly different. Linkages/control<br>
surfaces with any flex or slop will hide 99% of the differences in<br>
comparable servos. And, typically, all metal gear servos will weigh about<br>
.1 - .3 oz more.<br>
<br>
Regards,<br>
<br>
Dave <br>
<br>
<br>
-----Original Message-----<br>
From: <a href="mailto:nsrca-discussion-bounces@lists.nsrca.org"
ymailto="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</a><br>
[mailto:<a href="mailto:nsrca-discussion-bounces@lists.nsrca.org"
ymailto="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</a>]
On Behalf Of Jon Lowe<br>
Sent: Wednesday, January 07, 2009 8:56 AM<br>
To: <a href="mailto:nsrca-discussion@lists.nsrca.org"
ymailto="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a><br>
Subject: Re: [NSRCA-discussion] JR Servos of choice these days<br>
<br>
9411SA's (mid-size) on aileron, 8611a on rudder, 3421sa's on elevator <br>
(or my new choice, 3421's with the JRPSG3025 gear set middle two gears. <br>
Much faster, and plenty of torque, particularly on 6+ volts. On <br>
throttle, I use a servo mounted sideways (output shaft horizontal) <br>
directly on the engine mount, Hitec HS-56HB. Very tight and
fast. I <br>
change the throttle servos out after a year of use.<br>
<br>
I hope Dave Lockhart chimes in here. I'd like to find a faster <br>
alternative to the 9411sa's in the same size package.<br>
<br>
<br>
Jon Lowe<br>
<br>
<br>
-----Original Message-----<br>
From: Woodward, Jim (US SSA) <<a href="mailto:jim.woodward@baesystems.com"
ymailto="mailto:jim.woodward@baesystems.com">jim.woodward@baesystems.com</a>><br>
To: NSRCA-discussion <<a href="mailto:nsrca-discussion@lists.nsrca.org"
ymailto="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>><br>
Sent: Wed, 7 Jan 2009 7:19 am<br>
Subject: [NSRCA-discussion] JR Servos of choice these days<br>
<br>
<br>
<br>
<br>
<br>
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<br>
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<br>
<br>
<br>
<br>
<br>
<br>
<br>
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<br>
<br>
<br>
<br>
<br>
Guys,<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
I¢m finishing a pattern plane for a friend. He needs<br>
to know what the choice of JR servos are these days. I need two <br>
aileron servo<br>
choices, 1 rudder servo, 2 elevator mini digitals, and a mini for the<br>
throttle. Any recommendations would be great.<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
Thanks,<br>
<br>
<br>
<br>
Jim W.<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
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<br>
<br>
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