Servos for 1/3 extra 330
10-12-2004, 10:30 PM
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Servos for 1/3 extra 330
Hello Danny
I asked you a question something like this before. I have recently acquired Hangar 9 300 extra. Previous owner installed JR 2721 servos for the ailerons (one per aileron). Seems to perform well as near as I can see, but with 3D throw set up on the servos - there is 1/4 inch slop in trailing edge of control surface. I can actually see the surface flutter on low pass in flight. I think this is a problem re durability? and probably performance although I don't really notice it? The source of the 'slop' is not in the linkage - but rather in the servo centering / hold ability under the demands of this high throw. Obviously this is partly a function of control arm ratios needed to get the 3D throw. Question: are these servos adequate for this mission? Would digital servos make a big difference - re less servo lash at neutral or in displaced position? Which one (JR)? I know that 8611s are probably best -- other than expense, is there any downside to 8611s? I have the same servos on the elevators and same question. There is similar slop there, but I don't notice any flutter in flight?
Thanks for comments.
RJM
I asked you a question something like this before. I have recently acquired Hangar 9 300 extra. Previous owner installed JR 2721 servos for the ailerons (one per aileron). Seems to perform well as near as I can see, but with 3D throw set up on the servos - there is 1/4 inch slop in trailing edge of control surface. I can actually see the surface flutter on low pass in flight. I think this is a problem re durability? and probably performance although I don't really notice it? The source of the 'slop' is not in the linkage - but rather in the servo centering / hold ability under the demands of this high throw. Obviously this is partly a function of control arm ratios needed to get the 3D throw. Question: are these servos adequate for this mission? Would digital servos make a big difference - re less servo lash at neutral or in displaced position? Which one (JR)? I know that 8611s are probably best -- other than expense, is there any downside to 8611s? I have the same servos on the elevators and same question. There is similar slop there, but I don't notice any flutter in flight?
Thanks for comments.
RJM
10-13-2004, 08:59 AM
#2
RE: Servos for 1/3 extra 330
This may be due to gear wear if the servos have been in the plane for a while. The more load that is on the servo the faster the gear train will wear. It may be best to change the gear sets, or send them in for a check up. The 2721 is adequate for that application provided the mechanical set up is done by the book. The 8411 and the 8611 would be the next step up for servo choices, but they are similar price so if you are to buy new servos I would recommend the 8611. It has a tighter gear train that doesn't wear as fast, and much more power. Keep in mind that all metal geared servos will have some slop and is normal.
10-13-2004, 08:38 PM
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RE: Servos for 1/3 extra 330
Thanks Danny. I am wondering under what circumstances I would consider 8411 over 8611 if price is similar and holding power / torque is greater for 8611? Could you comment further re under what circumstance would 8411 be better servo. I have not been able to find info on 8611 on the web? Guessing it weighs more, draws more electrical power, that both are metal gears, and both have excellent ?
Related question - I have several 8411s, and have some concern re slop in set up (different airplane). Would it be worth while to rebuild with 8411SA gear train? Under what circumstance are metal gears required?
And another: I have several 2721 using them on 1/4 size planes. I have noticed wear over relatively short periods of time. It seemed to me (as I inspect them) that the wear is perhaps in the bearing surfaces within the servo housing as opposed to the gear train. Could this be the case.... and in this case, should I just rebuild them by buying new servo housing periodically?
Again, thanks for you comments. I a huge JR fan, particularly because of the great service you all provide us guys
.
Related question - I have several 8411s, and have some concern re slop in set up (different airplane). Would it be worth while to rebuild with 8411SA gear train? Under what circumstance are metal gears required?
And another: I have several 2721 using them on 1/4 size planes. I have noticed wear over relatively short periods of time. It seemed to me (as I inspect them) that the wear is perhaps in the bearing surfaces within the servo housing as opposed to the gear train. Could this be the case.... and in this case, should I just rebuild them by buying new servo housing periodically?
Again, thanks for you comments. I a huge JR fan, particularly because of the great service you all provide us guys
.
10-19-2004, 09:12 AM
#4
RE: Servos for 1/3 extra 330
Info on the 8611 can be found here:
http://www.horizonhobby.com/Shop/ByC...rodID=JRPS8611
I would say only if you want or need the 2 mm smaller size of the 8411 for installation in a plane, or you need to match other 8411's would I say go for the 8411. Otherwise, go with the 8611.
We recommend the 8411SA for 1.20 size aircraft or smaller. The high torque and holding power combined with the nylon gear train can strip gears in larger aircraft.
The only potential point for wear that I know of would be possibly the bushing for the center pin in the top half of the case. Otherwise, it is much more likely that if you see wear, that it is with the gear train itself.
http://www.horizonhobby.com/Shop/ByC...rodID=JRPS8611
I would say only if you want or need the 2 mm smaller size of the 8411 for installation in a plane, or you need to match other 8411's would I say go for the 8411. Otherwise, go with the 8611.
We recommend the 8411SA for 1.20 size aircraft or smaller. The high torque and holding power combined with the nylon gear train can strip gears in larger aircraft.
The only potential point for wear that I know of would be possibly the bushing for the center pin in the top half of the case. Otherwise, it is much more likely that if you see wear, that it is with the gear train itself.
