Flap Servo
10-25-2009 | 07:13 AM
#1
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Flap Servo
Hello Guys. Let me run one by ya and see if you have encountered this before. Have my flaps Y'ed to one channel on my 955 Jr. Rx. "Aux 2" Running a 10 X Tx. When I start out with a small amount of flaps, no Problem. The more I add the worse it gets as far as the two servo's staying together. They are Hitec 5645's. Is it normal for this to happen? One servo not staying with the other. I have tried this in 3 Diff Channels and it's the same . So thats the reason I fig. it's in the servo's I know I can set-up ec servo on it's own channel and would on a higher end jet, but for now is conv to run it like it is. Thanks Guys.
10-25-2009 | 07:26 AM
#2
RE: Flap Servo
My first thought by reading what is going on here is the servo arms are not exactly even with each other at rest.
As they travel during flap deployment, one arm is approaching the apex of the arc movement earlier than the other... it's a geometry thing.
It could also be the flap horns are not exactly in line at the hinge line and/or at different heights with each other, or the hole heights don't match (servo or horn).
As they travel during flap deployment, one arm is approaching the apex of the arc movement earlier than the other... it's a geometry thing.
It could also be the flap horns are not exactly in line at the hinge line and/or at different heights with each other, or the hole heights don't match (servo or horn).
10-25-2009 | 07:43 AM
#4
My Feedback: (44)
RE: Flap Servo
All Hi-Tec digital servos have the capability to have there speed programmed, did you verify the settings on a Hi-Tec programmer?
The Hi-Tec HPP-21 is a handy tool and it is relatively inexpensive.
Also (as a test) can you mix two separate channels together to verify the servo operation on independent channels to eliminate any possible influence that Y may have on the operation.
As mentioned, it could be as simple as the geometry of the linkages
Edit - I see you checked the linkages
The Hi-Tec HPP-21 is a handy tool and it is relatively inexpensive.
Also (as a test) can you mix two separate channels together to verify the servo operation on independent channels to eliminate any possible influence that Y may have on the operation.
As mentioned, it could be as simple as the geometry of the linkages
Edit - I see you checked the linkages
10-25-2009 | 07:54 AM
#5
Thread Starter
My Feedback: (106)
RE: Flap Servo
Rich, The verification with the programmer ran through my mind but at present, I don't have one. That, I guess will have to be my next move. As Mike touched on about the Geo, I thought about using "Bad" geo to correct the problem. On this jet, it's not a big thing but would be nice to correct it. I'm using the speed function in my 10X as well but don't think this could be it, as the two servos see the same voltage and input. Like you touched on I may need to check out that "Y" and make sure I'm getting the same current all the way through. I'm wondering if it would be worth the effort to change out to a analog type to check this? Thanks Rich.
10-25-2009 | 08:11 AM
#6
RE: Flap Servo
I've ran into the same problem many times and it's always been the two servos not traveling the same degree of rotation because of the allowable tolerances of the internal resistors on the pot / motors (non programmable servos as i don't use Hitech), if you're lucky you can usually get a 3rd servo and out of the 3 get a matched pair.
10-25-2009 | 08:22 AM
#7
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My Feedback: (106)
RE: Flap Servo
Rich, so am I guessing right on this servo programmer? If I had one inline, I could make the offending servo stop at or change it to stop at points to match the other servo?? I see five Ref/stop points in your screen shot of the programmer. Thanks for the input KC. Your nail on in what I was thinking. If this be the case than the programmer would be a fast fix. Is the programmer set-up to work with servo in plane in line or do you have to take it out to link it up with a PC?
10-25-2009 | 08:46 AM
#8
My Feedback: (40)
RE: Flap Servo
ORIGINAL: FILE IFR
My first thought by reading what is going on here is the servo arms are not exactly even with each other at rest.
As they travel during flap deployment, one arm is approaching the apex of the arc movement earlier than the other... it's a geometry thing.
It could also be the flap horns are not exactly in line at the hinge line and/or at different heights with each other, or the hole heights don't match (servo or horn).
My first thought by reading what is going on here is the servo arms are not exactly even with each other at rest.
As they travel during flap deployment, one arm is approaching the apex of the arc movement earlier than the other... it's a geometry thing.
It could also be the flap horns are not exactly in line at the hinge line and/or at different heights with each other, or the hole heights don't match (servo or horn).
My experience has been that flap servos need to be individually adjustable through either separate channels, a secondary mixer (Matchbox, Powerbox, etc..) or programable servos, if you want to get them exactly even.
Craig
10-25-2009 | 09:12 AM
#9
My Feedback: (44)
RE: Flap Servo
ORIGINAL: hooker53
Rich, so am I guessing right on this servo programmer? If I had one inline, I could make the offending servo stop at or change it to stop at points to match the other servo?? I see five Ref/stop points in your screen shot of the programmer. Is the programmer set-up to work with servo in plane in line or do you have to take it out to link it up with a PC?
Rich, so am I guessing right on this servo programmer? If I had one inline, I could make the offending servo stop at or change it to stop at points to match the other servo?? I see five Ref/stop points in your screen shot of the programmer. Is the programmer set-up to work with servo in plane in line or do you have to take it out to link it up with a PC?
Yes you can adjust the servo;s to match each other, as long as you have a long enough USB cable you can leave the servos in the plane, however I usually make all adjustments prior to installation.
10-25-2009 | 09:16 AM
#10
Thread Starter
My Feedback: (106)
RE: Flap Servo
Rich, Gonna have to keep my eyes open for a programmer and just set it up in a laptop beside the plane. Have several high-end laptops just sitting around . Will put one of them to good use!!! Ha. Need to sell one or two of these and turn them into another turbine engine!!! Ha. TNX for all your help gents.
10-25-2009 | 09:37 AM
#11
My Feedback: (44)
RE: Flap Servo
http://www3.towerhobbies.com/cgi-bin...?&I=LXWCE8&P=7
Tower sells them for $26.99, if you search you may find them for a couple of bucks less...
for an extra $25 bucks you can get the one that you can use standalone
http://www3.towerhobbies.com/cgi-bin...?&I=LXWCE9&P=7
Tower sells them for $26.99, if you search you may find them for a couple of bucks less...
for an extra $25 bucks you can get the one that you can use standalone
http://www3.towerhobbies.com/cgi-bin...?&I=LXWCE9&P=7
10-25-2009 | 09:56 AM
#12
RE: Flap Servo
I must be way out of touch but I bought the -20 Hitec programer over a year ago for somewhere around 160 dollars. I use it to set all my digital Hitec servos throws.
What am I missing in seeing Towers for 26.95?
Thanks,
Stan
What am I missing in seeing Towers for 26.95?
Thanks,
Stan
10-25-2009 | 10:06 AM
#14
Thread Starter
My Feedback: (106)
RE: Flap Servo
Rich, That looks like a neat gadget to have around for the price but gotta ask. I noticed in the Tech notes that it had Several features. Speed, Dir, EP and failsafe. Will this programmer allow me to even out say, the 90 Deg. flaps position and not change the 20/25 Deg.pos or the up flaps Pos? I have the servo's working great on the all up and at the 20/25 Deg. Pos. it's when I start moving down for more flaps that I need to adjust. They are not signaling the same linearity. I guess I need to bone up on this. I don't use many Y's as I just like to put everything essential on it's own Ch. and control it from the TX or use the feature for this on my Smart-fly boards.
10-25-2009 | 10:58 AM
#15
My Feedback: (44)
RE: Flap Servo
ORIGINAL: hooker53
Rich, That looks like a neat gadget to have around for the price but gotta ask. I noticed in the Tech notes that it had Several features. Speed, Dir, EP and failsafe. Will this programmer allow me to even out say, the 90 Deg. flaps position and not change the 20/25 Deg.pos or the up flaps Pos? I have the servo's working great on the all up and at the 20/25 Deg. Pos. it's when I start moving down for more flaps that I need to adjust. They are not signaling the same linearity. I guess I need to bone up on this. I don't use many Y's as I just like to put everything essential on it's own Ch. and control it from the TX or use the feature for this on my Smart-fly boards.
Rich, That looks like a neat gadget to have around for the price but gotta ask. I noticed in the Tech notes that it had Several features. Speed, Dir, EP and failsafe. Will this programmer allow me to even out say, the 90 Deg. flaps position and not change the 20/25 Deg.pos or the up flaps Pos? I have the servo's working great on the all up and at the 20/25 Deg. Pos. it's when I start moving down for more flaps that I need to adjust. They are not signaling the same linearity. I guess I need to bone up on this. I don't use many Y's as I just like to put everything essential on it's own Ch. and control it from the TX or use the feature for this on my Smart-fly boards.
I have found that if I adjusted my center points and end points the same there has never been an issue with the linearity.
10-26-2009 | 05:41 AM
#17
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From: RockinghamWestern Australia, AUSTRALIA
RE: Flap Servo
HI Mate for what it is worth I only use analog servo's on my flaps (645's) and have never had the problem I think Hitec & JR only recomend analog's for flaps.
Mav
Mav
10-26-2009 | 06:53 AM
#18
RE: Flap Servo
ORIGINAL: mavrick
........... JR only recomend analog's for flaps.
........... JR only recomend analog's for flaps.
10-26-2009 | 12:01 PM
#19
My Feedback: (11)
RE: Flap Servo
I'm a huge believer in the high end HiTec servos (59, 79), BUT I've had the wierdest lock ups, bad centering, just overall strangeness happen to me with 5645's and wouldn't trust that servo in any jet and especially a critical surface like a flap. My advice: get rid of all your 5645's and get the coreless 59 or 79.
Raf
Raf
10-26-2009 | 04:02 PM
#20
Thread Starter
My Feedback: (106)
RE: Flap Servo
Mav, You parralled my later thinking. Raf, Didn't want to say it or even think it but understand what you are saying and I have came to the conclusion that all the surfaces on a jet are important enough to think about your servo's. I have some metal gear 605's I thought about trying. KC, I love JR digitals. Thanks all.
