[NSRCA-discussion] JR Servos of choice these days

[John Konneker]

Dave,
Thanks!
I cut and pasted the email in to a Word doc and saved it in my "Neat Stuff" folder!
:-)
JLK> From: DaveL322 at comcast.net> To: nsrca-discussion at lists.nsrca.org> Date: Wed, 7 Jan 2009 13:10:45 -0500> Subject: Re: [NSRCA-discussion] JR Servos of choice these days> > Ok....here goes...> > My "standard" servo package for many years has been: > 9411sa on ailerons > 8411sa on rudder > 8417sa on elevator > 3421sa on throttle (better yet, Castle 85 HV <G>) > > As FYI for those not familiar with JR servo nomenclature - > - DS prefix indicates digital. > - MG indicates metal gear. > - SA indicates metal and nylon geartrain (generally metal pinion on servo> motor, with metal output shaft, and 2 or 3 intermediate gears are nylon). > - 4 digit number indicates coreless motor. > - 3 digit number indicated cored motor (3 or 5 pole). > - 1st number indicates general case size (ie, 8411 and 821 share same> mounting pattern). > There are some exceptions, but the above is applicable to most current and> past JR servos. > > Speed and torque generally increase proportionately to increased voltage,> and I have always run relatively high voltage to improve servo performance.> In my glow days, I used 5 cell unregulated Nicd or Nimh to power the> receiver and servos, and "bump" charged every couple flights to keep the> battery voltage high. When I converted to electric powerplants, I started> using (in parallel) 2 sets of TP 2s1p480 lipos regulated to 6.53 volts> through Tech-Aero Vregs. > > 8417 - is only available as a MG servo. The 8417sa is an 8417 that has had> the 3 intermediate metal gears replaced with the nylon gears from an 8411sa> or 8231 (buy the 8231 gearset, it is all nylon, and costs less). 8231 gear> ratio is slightly slower than the 8417, so an 8417sa at 6.5 volt is about> 0.09 sec and 130 oz/in torque. > > 9411 - I don't know of a midsize JR servo better suited for ailerons (save> running 6.5 volts instead of 6 volts, which is good for about 0.01 sec on> that servo). > > 3421 - I've used this servo a lot (including pairs mounted horizontally on> the engine mount for the Webra 160MC), but never in pairs on elevator as I> prefer a single servo. However, the 3421sa is a good choice (in pairs) for> elevator @ .015 sec and 75 oz/in torque @ 6v. The 3517 is another option -> slightly faster (and less torque) - 0.09 sec and 51 oz/in torque @ 6v.> > 8411 - this servo is close to 200 oz/in @ 6.5v. Several years ago, I ran> the 8411sa and 8611 back to back in my EMC, and I couldn't tell the> difference between them in flight, so I've stayed with the 8411 as it is> lighter (and the rudder size has not increased on the majority of planes> since that time - but the fuses have!). > > Brief sidenote about metal / nylon gears. Metal gears are for strength> (especially when space is at a premium), but are typically manufactured with> small clearances (slop) to avoid binding. Nylon gears can have zero> clearance without binding (gears flex instead) have better wear properties.> I find the nylon gears ever so slightly more accurate for very fine control> inputs ("leaning" on the stick, without actually moving the stick).> However, the nylon stuff will deflect ever so slightly under load, whereas> the metal gears do not flex under, so the "personality" of the servos at> center and just off center can be slightly different. Linkages/control> surfaces with any flex or slop will hide 99% of the differences in> comparable servos. And, typically, all metal gear servos will weigh about> .1 - .3 oz more.> > Regards,> > Dave > > > -----Original Message-----> From: nsrca-discussion-bounces at lists.nsrca.org> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Jon Lowe> Sent: Wednesday, January 07, 2009 8:56 AM> To: nsrca-discussion at lists.nsrca.org> Subject: Re: [NSRCA-discussion] JR Servos of choice these days> > 9411SA's (mid-size) on aileron, 8611a on rudder, 3421sa's on elevator > (or my new choice, 3421's with the JRPSG3025 gear set middle two gears. > Much faster, and plenty of torque, particularly on 6+ volts. On > throttle, I use a servo mounted sideways (output shaft horizontal) > directly on the engine mount, Hitec HS-56HB. Very tight and fast. I > change the throttle servos out after a year of use.> > I hope Dave Lockhart chimes in here. I'd like to find a faster > alternative to the 9411sa's in the same size package.> > > Jon Lowe> > > -----Original Message-----> From: Woodward, Jim (US SSA) <jim.woodward at baesystems.com>> To: NSRCA-discussion <nsrca-discussion at lists.nsrca.org>> Sent: Wed, 7 Jan 2009 7:19 am> Subject: [NSRCA-discussion] JR Servos of choice these days> > > > > > > > > > > > > > > > > > > > > > > Guys,> > > >  > > > > I’m finishing a pattern plane for a friend.  He needs> to know what the choice of JR servos are these days.  I need two > aileron servo> choices, 1 rudder servo, 2 elevator mini digitals, and a mini for the> throttle.  Any recommendations would be great.> > > >  > > > > Thanks,> > > > Jim W.> > > >  > > > >  > > > > > > > > > > > > > _______________________________________________> NSRCA-discussion mailing list> NSRCA-discussion at lists.nsrca.org> http://lists.nsrca.org/mailman> /listinfo/nsrca-discussion> > > > > > _______________________________________________> NSRCA-discussion mailing list> NSRCA-discussion at lists.nsrca.org> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion> > _______________________________________________> NSRCA-discussion mailing list> NSRCA-discussion at lists.nsrca.org> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
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