SERVOS VIPER ?
09-30-2003, 09:08 AM
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RE: SERVOS VIPER ?
You do not need metal gears, and in my opinion they are not suited to these types of planes. The metal geared servos are significantly heavier than the Nylon gears, and they also tend to develop slop much quicker. The Nylon gears seem to hold up just fine, after years of use.
Another servo worth considering is the Expert SL451 available at Horizon. Specs are near identical to the JR 3121, and I would question that they may very well be the same servo. The SL451s' go for about $24 each. I haven't tried this servo yet, but will be outfitting a few planes with them this winter for testing
Another servo worth considering is the Expert SL451 available at Horizon. Specs are near identical to the JR 3121, and I would question that they may very well be the same servo. The SL451s' go for about $24 each. I haven't tried this servo yet, but will be outfitting a few planes with them this winter for testing
09-30-2003, 10:25 AM
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RE: SERVOS VIPER ?
I've used metal gears a lot, and I have to agree about the slop. On my sport F3D/30, I've got metal gears in the wing servos. After somewhat over 200 flights, they are much sloppier than the rudder and elevator that have nylon gears.
The only advantage I see to metal gears is that they hold up better in a flutter situation. Plus, if you can afford to change out the servos on a regular basis, they do feel tighter for a while.
I put HS-85MG's in my first Viper (on elevator) and HS-81's in the second one. The first one does feel tighter, but the pushrods could be the variable instead of the gears.
Both of them use only 2 screws, so any slop (and there is very little on either) could actually be because they don't have 4 screws. I went with the lighter servos because of the out of box weight of the Viper.
I wasn't sure if the 81's would be strong enough, but so far they feel fine.
The only advantage I see to metal gears is that they hold up better in a flutter situation. Plus, if you can afford to change out the servos on a regular basis, they do feel tighter for a while.
I put HS-85MG's in my first Viper (on elevator) and HS-81's in the second one. The first one does feel tighter, but the pushrods could be the variable instead of the gears.
Both of them use only 2 screws, so any slop (and there is very little on either) could actually be because they don't have 4 screws. I went with the lighter servos because of the out of box weight of the Viper.
I wasn't sure if the 81's would be strong enough, but so far they feel fine.
09-30-2003, 11:36 AM
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RE: SERVOS VIPER ?
I would be hesitant to use 81s on anything other than throttle. I have even stripped the gears using this servo on throttle cables with minimal resistance.
I have much better luck with the HS 85 (Same case as the 81, but with ball bearings). Once again, I still prefer the Nylon gear version of the HS 85.
On a Sport motor .40 / .46, I see no reason why you couldn't get away with the smaller and lighter HS 85 servos on each elevator half (V-tail) except for the small play you get with them due to only two screws holding them down. I've seen people use these on Nelson powered quickees, but I personally wouldn't feel comfortable doing that
I have much better luck with the HS 85 (Same case as the 81, but with ball bearings). Once again, I still prefer the Nylon gear version of the HS 85.
On a Sport motor .40 / .46, I see no reason why you couldn't get away with the smaller and lighter HS 85 servos on each elevator half (V-tail) except for the small play you get with them due to only two screws holding them down. I've seen people use these on Nelson powered quickees, but I personally wouldn't feel comfortable doing that
09-30-2003, 12:19 PM
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RE: SERVOS VIPER ?
I agree Dave ... but I was down to one unused 85, and decided to try the 81's just to find out. They're rated at 36 oz. in. and the old 1999-2001 spec made 25 oz. in. the minimum for a V-tail or separate ailerons, even for 422/428.
I may put a 428 engine on the Viper 500 with 85's, but I definitely won't go over a 424 engine with the 81's. Actually, I plan on putting an OS .25 FX on the one with 81's to demo Slow Quickie.
I may put a 428 engine on the Viper 500 with 85's, but I definitely won't go over a 424 engine with the 81's. Actually, I plan on putting an OS .25 FX on the one with 81's to demo Slow Quickie.
09-30-2003, 02:32 PM
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RE: SERVOS VIPER ?
I have considerable experience w/ the Expert Line and they are the same as the JR Line. The SL300 is the JR 331, and the SL451 is the JR 3121. For a single aileron servo,
do not use either. The gear train on the SL451 is lousy and will strip out at the stops everytime. The Expert SL300 can be used sucessfully as a double wing servo and
rudder/elevator, one word of caution, it is a three pole motor same as JR331, and will not hold up on a 5 cell pack, however the JR341 will do nicely. I have gone thru 3 dz.
of the SL 300 & JR331 on 5 cells. Don't use!! 4 cell only, which puts the torque in the 30in/oz range
Bryant
do not use either. The gear train on the SL451 is lousy and will strip out at the stops everytime. The Expert SL300 can be used sucessfully as a double wing servo and
rudder/elevator, one word of caution, it is a three pole motor same as JR331, and will not hold up on a 5 cell pack, however the JR341 will do nicely. I have gone thru 3 dz.
of the SL 300 & JR331 on 5 cells. Don't use!! 4 cell only, which puts the torque in the 30in/oz range
Bryant
