Servo died during flight

[flydiver]

Here is some useful info on fixing and getting to know a lot more about servos: Servo Survival Guide
Ignore the thread title - go to post # 165
www.rcuniverse.com/forum/m_4790624/mpage_7/key_/tm.htm

As a bunch of you have probably figured out I spend too much time on the various forums and threads. I collect info, put it in files or bookmark it (you think I can remember all this stuff?) and try to remember where I put it. So here is a random collection of snips about servos that seem to be valid based on a number of similar postings. It is not my experience and may not be yours. There is some utility in the collective intelligence of a lot of people.

So in no particular order (remember-these are not MINE, I snipped them from the RC community):
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Just a word to the wise though, stay completely away from E-Flite S-75 and Spektrum S-75 servos! I have some Spektrum servos I haven't tried yet, but the E-flites are basically the same ones with a different label and the ones I have are terrible.

I have about 16 GWS Pico and Pico BB's (GWS). No slop and never stripped a gear. They are my workhorse servos.

futaba s3110s are great, way quicker, smaller, and WAYYYY more torque than an HS-55.

Moved on to Futaba S3110s. Same price range, much more torque, a little faster and a little smaller than HS-55s and GWS Naros. Have yet to have a stripped gear problem or any problem with them.

A friend has been using the 9320MG and 9314MG servos with great success so far. I was under the impression the 9314 was just a slightly smaller servo than the HS81-sized 9320. Not, much smaller, more like a HS55 size range. Either way, he likes'em both real well. Soon as my rotting stock pile of HS81s is used up I'll be getting the 9320MG for situations I would only trust an HS81 to before (elevator, elevons on a Stryker, etc). 9314 might make a good aileron servo on builds with a 3 foot to 4 or so wingspan. Any bigger and I'll go to the 9320. Plan to use the HXT900 for situations where the HS81 is a tad overkill,

We can say that the 9320 is a very popular servo, and we have had but a handful returned under warranty, in the thousands upon thousands sold.
The 9320 uses the same motor and pot as the HS81. I've had one pot fail so far out of four servos, not worth returning all the way to China for warranty.

Best servo discussion in Sailplanes:
Sub-micro: Had nothing but good luck with HS-56's. Now available in a metal gear digital version, the HS-5056.
Micro: HS-65MG, HS-5065MG are great. JR DS-368 is outstanding, Airtronics 94761 is probably the best micro out there. The new DS378 is supposed to be one of the best as well, but I haven't tried it yet.
Mid-size: Doesn't get any better than the JR DS3421.

If I had to standardize on one servo for 2M and above, and budget was an issue, then the Hitec HS-85BBhttp://www3.towerhobbies.com/cgi-bin...&I=LXN682&P=ML

So as I go forward I am moving more to ball bearing supported analog servos, like the HS-56 where space is tight, or HS-85s where they will fit. I can't see any reason to use anything bigger than the 85s.


Worst: Dynam 8g, 21 oz-in servos
The worst? The little Dynam 8g servos. Slow, weak and really bad centering.
The MG995 are *awful*
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There you go, a grab bag if semi-sorted info. Obviously this only scratches the surface of the number of servos that are out there.
If price were no object I'd probably put Hitec HS-65HB or MG in most of my park fliers.

[john66]

Thanks for sharing that Fly, alot of info to collate.

John

[Dillzio]

I went flying yesterday, and another Corona aileron servo carked it.

A mate of mine has a horse, and I took my plane for a fly at the paddock he keeps his horse at. I had a keyfob camera velcroed to the battery door, and was looking forward to getting some nice video of the paddock and the horses.

Half way through my second battery the servo died, but at least this time it died in a neutral position. Even though the servo was at neutral position, it still made the plane really difficult to fly, as it would roll one way without any trouble, but getting it to roll the other way to return to level flight was really difficult, just about impossible without using the rudder.

I managed to bring it in for a landing without any major damage, but it did hit the ground pretty hard and the camera came off. I spent at least 20 mins looking for it amongst the grass, weeds and horse $hit, but didn't end up finding it. The camera with the 8gb memory card in it was worth about $25.

I haven't done the autopsy yet to find out exactly what went wrong, but for now it's looking like the Corona 928BB servos might be worth keeping away from

[flydiver]

Your service to the community for identifying crap is appreciated.

[Dillzio]

Gee, thanks Fly, it's my honor and privilege to be your guinea-pig.

I guess someone had to try out the Corona servos, they were either going to be better or worse than the HXT900s. It was a gamble, and it appears I lost. Now I'm faced with the PITA of having to make HXT900s fit into the holes for the Coronas. I've made a hot-wire cutter out of a soldering iron to put the holes in last time, by using that to cut out more foam, and using good old Selleys white gap-filler to fill the holes it should come out pretty well. I use that gap filler to stick in servos and firewalls, it's good stuff.

The HXT900s don't have as much travel as the Corona 928BBs, but they do have longer servo arms so hopefully they will both have about the same throw.

[john66]

Bummer sorry to hear that Dill. Those Coronas definitely sound like they need to be avoided. Bummer about not finding the cam too.

Did it spook the horses when the plane came down?

John

[Dillzio]

Cheers John. Nah, it didn't spook the horses at all. It landed near me, and I was about 200m from the horses, so I wasn't taking off or landing anywhere near them. I did a few passes over the heard trying to get some nice shots, progressively getting lower and lower. It got their attention and they looked up at it, but it didn't seem to spook them at all.

I'll have to keep an eye out whenever I'm at that paddock from now on, who knows, one day I may find it and end up with a very funny video of me looking for the camera. I wonder how close to finding it I actually got?

[flydiver]

Hey, I didn't ask you to.

I tried to upgrade from the HXT900 to some $20 Bluebirds when I got my coveted Weasel. Stripped one on the first dork. I didn't strip a HXT in dozens of worse dorks.
One nice thing is they sell a metal gear upgrade. Another $20 and now I have Bluebirds with metal gears....only one of them won't work. It keeps freezing up after it sits for awhile. Frees up with a hard twist and works again but just can't be trusted in the air.

[Dillzio]

I've finally gotten around to making the switch to the HXT900s, yet to fly the plane with them thought. Making them fit in the wings was not as difficult as I thought it would be, I just needed to cut out two little pieces of foam for the taps that come off of the servo to slop into.

I found an excellent way of installing servos into the wings. I use white selleys gap filler, first I put a thick ring in the base of where the servo is, and around the edges of the hole for the servo. With a bit of spit on your finger, push the sealant away from where the servo arm will be, you don't want the gap filler gunking that up. Then I get about 15cm of electrical tape, attach it to the servo, then cover the bottom and sides of the servo in the sealant (making sure not to get any on the tape). Then you pull the tape really tight and use it to stick the servo into place. Then you just get something flat like a ruler, push that down along the servo to get it flush with the rest of the wing, then leave it overnight to set.

The tape works really well because it holds the servo in the correct spot while it sets, it gives you an excellent indicator of if your servo is level or not, and it sticks to the servo and prevents it from going too low as well.