Hitech HS65HB servos - stripped my first ones

[thevon]

I've had a really high opinion of the Hitech HS65HB servos with the Karbonite gears. I love them and quite a few local flyers are using them without problems, even on planes that take a beating (eg Ken has 4 of them on his Reaper). So far I haven't heard of anyone here stripping one. But the other day I was flying my Wizard Compact BPV and did what I thought was a nice landing approach. I thought I was dropping it into the grass but belly flopped it really flat on the dirt road which I couldn't seen from where I was standing. It was quite a slow landing but it fell in dead air, only for less than a foot, maybe 6 inches. But it made quite a whack as it landed. Sean said it landed basically horizontally on the fuse. When we picked it up we found that one V-tail servo was completely stripped. I later found that the other one has free play at centre, so must have stripped a tooth too.

It made for a rather expensive landing. The Wiz came to me with digital metal geared JR 362's in the fuse, but I swapped them for the HS65's which I thought were more than adequate for the job. I wanted to use the 362's to replace sloppy ones in my Fazer. Now I sort of wish I'd left the 362's in there!

I was surprised that a flat smack landing was enough to wreck those servos. The V-tail didn't get hit and the plane landed quite flat. I guess that the smack must have yanked down on the control rods in the fuse and jerked the servo arms that way.

I'm wondering if it was a freak event or whether I should change back to stronger servos. Has anyone else had any problems with HS65's?

[skyboyken]

Sorry to hear it Andrew!

Sounds like it was a shock load that was transmitted to the servos by the control rods. If that's the case then I would suggest just putting new gears in the 65's as it's pretty unlikely to happen again (unless you plan to make a habit of smack landings on roads ).

If you think it may happen again you could put metal gears in the 65's.

Of course the final step if you were really concerned would be to replace the servos, and as you'll want something as slop-free as possible I would suggest the Airtronics digitals - they have NO slop out of the box (unlike some JR digitals) and both Eric and I are using them with total success so far. For info I got mine from SoaringUSA for $US60 each.

Really though, replacing servo gears is part of the game (we used to do it every year in comp gliders) and shock loads like that are IMHO a rare occurrence, so I do suggest you just replace the gears this time and reconsider if it happens again.

Ken.

[thevon]

Can we easily get gears for the 65's?? I'm being lazy asking - I haven't looked. But I have 2 servos here in need of gears!

[thevon]

PS I got this reply from Mike the Snake on the RC Groups forum thread:
www.rcgroups.com/forums/showthread.php?t=904424#post10287995


That flat smack landing is enough to blow out most ANY servo gears that are not metal. Your problem lies in not using metal geared servos.
The HS65mg is probably THE best servo available in it's size. Check the mini heli forums. The HS65mg is preferred over even the brand name digitals.
The Wizard BPV has the full-flying tail? If so, the weight of the FF tails definitely contributed to the gearsets stripping as well.
Switch the gears out to metal gears and you won't have this problem again. The HS65mg servo has silky smooth metal gears, super strong too.

[Vanders]

Andrew, I'm pretty sure Rojs Hobbies sell the gearsets for the 65HB's.

www.rojshobbies.com/Home.html

[portfox]

Andy, also have a look at the equivilant Futaba ones, similar price and digital (Futaba S3156 Servos)

[thevon]

Guys, Budget Hobbies at Capalaba had the full gearsets for around $6 per set. He said they hadn't actually sold any yet as they didn't know anyone that had stripped one! He gave me some good advice about assembling them but apparently it's pretty straightforward and they're a very positive fit.

They also had the HS65MG metal geared servos for $39.50 each, which I think is a competitive price so I got 2 of them. I'll put them in the Wizard to prevent similar future problems.

[Vanders]

Good guys there at Budget Hobbies!