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Dave,<BR>
Thanks!<BR>
I cut and pasted the email in to a Word doc and saved it in my "Neat Stuff" folder!<BR>
:-)<BR>
JLK<BR><BR>> From: DaveL322@comcast.net<BR>> To: nsrca-discussion@lists.nsrca.org<BR>> Date: Wed, 7 Jan 2009 13:10:45 -0500<BR>> Subject: Re: [NSRCA-discussion] JR Servos of choice these days<BR>> <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: nsrca-discussion-bounces@lists.nsrca.org<BR>> [mailto:nsrca-discussion-bounces@lists.nsrca.org] On Behalf Of Jon Lowe<BR>> Sent: Wednesday, January 07, 2009 8:56 AM<BR>> To: nsrca-discussion@lists.nsrca.org<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) <jim.woodward@baesystems.com><BR>> To: NSRCA-discussion <nsrca-discussion@lists.nsrca.org><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>> NSRCA-discussion@lists.nsrca.org<BR>> http://lists.nsrca.org/mailman<BR>> /listinfo/nsrca-discussion<BR>> <BR>> <BR>> <BR>> <BR>> <BR>> _______________________________________________<BR>> NSRCA-discussion mailing list<BR>> NSRCA-discussion@lists.nsrca.org<BR>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion<BR>> <BR>> _______________________________________________<BR>> NSRCA-discussion mailing list<BR>> NSRCA-discussion@lists.nsrca.org<BR>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion<BR><BR></body>
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