<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><DIV>Dave,</DIV>
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<DIV>Isn't the JRPS3517 a relabeled JRPS3400G ??</DIV>
<DIV>Identical specifications except 3400 never came out with MG.</DIV>
<DIV>I'm going to try 3400Gs on Elevators since they show same spec with 3517 unless Horizon doesn't recommand it? </DIV>
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<DIV>Ihncheol<BR></DIV>
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<B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> Dave <DaveL322@comcast.net><BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> General pattern discussion <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></FONT><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><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><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>_______________________________________________<BR>NSRCA-discussion mailing list<BR><A href="mailto:NSRCA-discussion@lists.nsrca.org" ymailto="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</A><BR><A href="http://lists.nsrca.org/mailman" target=_blank>http://lists.nsrca.org/mailman</A><BR>/listinfo/nsrca-discussion<BR><BR><BR><BR><BR><BR>_______________________________________________<BR>NSRCA-discussion mailing list<BR><A href="mailto:NSRCA-discussion@lists.nsrca.org"
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