Spoiler servos - RC Groups
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Nov 09, 2017, 01:53 PM
What, Me Worry?
edbu1's Avatar
Discussion

Spoiler servos


I just built (from a kit) a Bird of Time and have installed spoilers. To actuate, I am using Hitec HS-55 servos, but they make noise quite a bit. The kind of noise that indicates they are being over-stressed. What servos would you recommend that will fit in such a thin wing, but has more torque and therefore not subject to being over-taxed? Can't go any thicker than the width of the HS-55 servo, which the Hitec web site says is 0.45 inches (12 mm). Torque is 15.27 oz-in. Each spoiler itself is made of 1/8 inch balsa, spans 2 wing bays, but is 2 inches wide (chord-wise).
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Nov 09, 2017, 02:04 PM
Sagitta Fanboy
Just about any 9g alternative will be better than the HS-55 which are an old design and on the weak side for the class.

For a particularly good option, look at the power version of the Dymond D47, they're about $20 each. do 20oz-in at 4.8V and are 4.7g
Nov 09, 2017, 02:09 PM
Mark LSF # 3792
What? Over-stressed lifting a piece of balsa that can't weigh more than 1/8 of an ounce? I've never owned nor run a pair of HS-55's, but that sounds suspect to me. What type of linkage system are you using?

OOH, when do you hear the stress?
Nov 09, 2017, 02:19 PM
What, Me Worry?
edbu1's Avatar
I've got a nylon control horn on the spoiler with an EZ connector holding a wire that connects to another EZ connector on the servo arm. No binding. It moves easily. You are right in that it does seem to take about no effort to open the spoiler. I have adjusted the end points electronically to make the travel as little as possible to open and close. Maybe it's just the servos.
Nov 09, 2017, 07:05 PM
ʇsol
vulturetec's Avatar
HS-55s are noisy. I've used them on two spoiler installations and they've been fine - but noisy.
Latest blog entry: Gentle Lady build
Nov 10, 2017, 02:36 AM
Faster is Better
Slopemaster's Avatar
I use HS 55's for spoilers on my DAW KA-6, 3 meter. No issues, original servos with 15 years of frequent use.
Nov 12, 2017, 01:27 PM
B for Bruce
BMatthews's Avatar
Quote:
Originally Posted by edbu1
I've got a nylon control horn on the spoiler with an EZ connector holding a wire that connects to another EZ connector on the servo arm. No binding. It moves easily. You are right in that it does seem to take about no effort to open the spoiler. I have adjusted the end points electronically to make the travel as little as possible to open and close. Maybe it's just the servos.
The part in bolt concerns me a little. To get the full power out of any servo you want to use as much of the servo travel as you can. The fact that you write that you made it so the travel is as little as possible would be a bad thing. Or are you just describing what you did badly?
Nov 13, 2017, 01:19 PM
What, Me Worry?
edbu1's Avatar
What I am saying about adjusting the end points is to make it clear that the servos are not making noise due to stalling when they reach the end of the travel linkage. The servos are not getting hung up on the mechanical linkage.
Nov 13, 2017, 03:58 PM
B for Bruce
BMatthews's Avatar
OK, that's fine.

Do they seem like they are traveling slower than they should? Can you fairly easily pull the output arm off and run the servos in the wing without the spoilers connected. Or if that's not easy try pressing down a spare HS55 on the spoiler or over the spoiler servo's hatch with a small stick or screwdriver and run THAT one off a spare receiver. It may just be that the wing covering is acting like the soundboard of a guitar and magnifying the noise.
Nov 14, 2017, 06:16 AM
Registered User
birdyfly's Avatar

HS-40 Servo


In our F3RES model Impression from rs-aero.com we use HS-40 servos.

The servos are included in the kit and work perfectly!
Nov 14, 2017, 07:06 AM
What, Me Worry?
edbu1's Avatar
Thanks for the input, Bruce. The HS-55 servos travel quickly as they should. They are new servos that I just purchased. I believe the sound that I hear is just the way they are. At this point, I will live with it and perhaps change them out. So I am looking for recommendations for alternate servos that are no wider than the 0.45 inch (12mm) that these are.
Nov 14, 2017, 07:28 PM
Brett
bjaffee's Avatar
To BMatthew's point, you want to make sure that the linkage is adjusted (if possible) so that you can maximize the travel of the servo arm and get as much torque as possible. Use the shortest servo arm you can, along with the largest lever arm on the spoiler itself. That should allow you to increase your end points, which will reduce the load on the servo.
Nov 16, 2017, 04:26 PM
B for Bruce
BMatthews's Avatar
Another point is that they are only loud on the bench. Once out at the field and you apply the spoilers while in the air they will be delightfully silent.....

A lot of the less expensive servos are fairly noisy. If the arms move in a smooth manner I wouldn't worry about a bit of extra noise. And for what it's worth I've always found that servos are more noisy when in a built up and covered wing than inside a fuselage. The 55's are actually a fairly decent servo in that size and price range.
Nov 16, 2017, 04:45 PM
Registered User
craigrrr's Avatar
I have used a lot of HS-55, E-Max, and other light cheap servos for spoilers.

Regarding noise, I always have the servo arm pushing directly on the bottom side of the spoiler.
Retraction is done by a tiny rubber band segment pulling the spoiler down. Some people use a magnet.
When retracted, the servo arm has nothing touching it, so it probably will remain silent.

Craig


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