• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.
Pumpkin drop event

Anyone else keep stripping the 9 gram servos on the Versa Wing?

#1
I have stripped the teeth off 4 of the Hextronic HXT900 9g blue servos - pretty much one every outing since building the Versa Wing. I think this is happening in the air as I lose control and then fall out of the sky (generally nose-first), so I don't think I'm hitting the elevons on landing.

Could this be due to the forces involved in sharp turns? I am a complete beginner so not exactly going easy on the thumbs trying to get it in the air (when it happens it's usually in the first 5 seconds after takeoff, when I'm trying to get it straight and level).

Could it be due to too much travel on the throws leading to larger forces? I have more throw than Josh recommended to help with slow flight/takeoffs and have 50% dual rates (about what Josh had in the build video) for normal flight. Is this common to strip servos if the throws are set too high?

Wondering if others tend to use bigger/stronger/metal toothed servos to prevent this on planes of this size/weight? If so, any recommendations on which ones to buy?

Cheers,
Tim.
 
Last edited:

xuzme720

Dedicated foam bender
Mentor
#2
Are you sure you aren't over-driving the servos? When you have elevons, the throws combine when giving both inputs in the same direction, for instance, commanding a right turn and up elevator will multiply on the right elevon. I've never stripped a servo this way but have heard of it happening.
A more likely cause is some kind of impact to the control surface. Is it possible that the elevons aren't hitting the ground during a cartwheel or something?
I have the 9 grams on mine and so far have not stripped them...given it a good try though!
 
Last edited:
#3
Are you sure you aren't over-driving the servos?

A more likely cause is some kind of impact to the control surface. Is it possible that the elevons aren't hitting the ground during a cartwheel or something?
I have the 9 grams on mine and so far have not stripped them...given it a good try though!

Hi Gary, hmm, don't recall cartwheeling it, though I was soo excited I may have missed it! I tested full range (for example full left with full up) before flying without issue, but will definitely dial back the throws next time; I might fly on 50% dual-rates to see if that makes a difference. Will watch the build video again to see if I missed anything.

If it happens again I think I'll get some metal toothed servos to see if that makes a difference.

Sidenote: I just taped up a couple of sheets of foamboard with red parcel tape ala Experimental Airlines ready for a Bloody Wonder V2 build. I'm interested to compare how easy that one is to fly vs the Versa Wing.

Cheers,
Tim.
 

xuzme720

Dedicated foam bender
Mentor
#5
Hi Gary, hmm, don't recall cartwheeling it, though I was soo excited I may have missed it! I tested full range (for example full left with full up) before flying without issue, but will definitely dial back the throws next time; I might fly on 50% dual-rates to see if that makes a difference. Will watch the build video again to see if I missed anything.

If it happens again I think I'll get some metal toothed servos to see if that makes a difference.

Sidenote: I just taped up a couple of sheets of foamboard with red parcel tape ala Experimental Airlines ready for a Bloody Wonder V2 build. I'm interested to compare how easy that one is to fly vs the Versa Wing.

Cheers,
Tim.
If you tested before then that probably isn't it. I wonder if maybe you got a bad batch of 9grams?
 

Epitaph

Ebil Filleh Pega-Bat ^.^
Mentor
#6
I always thought that "overdriving" servos problem died when they stopped using mechnical rail mixers, as an EPA is set to the servo and the computer mix will only adjust the servo not on the limit when using 2 inputs at the same time...
 
#8
Just stripped a 9gram servo on a FT-22 when the elevon hit the ground yesterday, it was a turnigy model 9 gram blue body servo. The hobby king web site warns that the turnigy are prone to breakage in rough landings. I had bought a couple gear repair sets from HK and was able to get it working today!
 

xuzme720

Dedicated foam bender
Mentor
#9
I always thought that "overdriving" servos problem died when they stopped using mechnical rail mixers, as an EPA is set to the servo and the computer mix will only adjust the servo not on the limit when using 2 inputs at the same time...
That might be why I haven't seen it myself...I have had servos hit the surface travel limit when the mixes pile up...Haven't killed a servo that way though, since I adjust that out when it happens.
 
#10
I stripped a couple of Hextronix 9grams when i had a flying wing as well (Tek Sumo). Mostly from crashing though. You may want to check how hard the effort is for the servo. Can you move the elevon with your finger with ease? I have put too much glue in the joint before and it makes the elevon hard to move, or the straw, is it dragging on the control rod? I have had servos strip because of that before. Otherwise, if you want, www.valuehobby.com makes a metal gear servo that is 9g that is only $7.00 I love them, a little more heavy duty
 
#11
Yes I can move the elevon pretty easily with my finger and there is no tube on mine, I strengthened the control rods with kebab skewer 'splints', so that's not the issue.

Thanks all, think I'll get a handful of the metal gear servos in addition to some more HXT900s and see what happens. Either way it's a pretty cheap repair so I'm not too concerned. As my skills improve it may stop happening! I'll try concentrate on my next crash and watch what parts of my plane smash into the ground the most!