Dave Wave

Regarding the post on wearing out servos, someboady posted that they really liked the HXT900 servos. I have had some experience with the COX micro servos that were about the same price and was unimpressed with the quality and would not fly with them. Anybody with first hand experience with these servos care to chime in as to their quality?

Thanks!


-Dave

Mr Cox

I would like to chime in against the HXT900 servos, to me they are weak and of poor quality, they can perhaps be used in indoor foamies, but have no place in real planes.

mtntopgeo

My Feedback: (12)

You're probably gonna get some different opinions here. After going through a load of gear sets on the hs55 servos. (never in the air, but from belly landings, & "rough" handling in the trunk of the car, to & from the field.) I switched over to the HXT 900 units 'bout 2 or 3 years ago. I use them in all my .15 & under size planes. Have not seen any evidence of weakness that Mr. Cox has experienced, but there are a couple of issues,. There is a bit of a quality problem with them. Every once in awhile I'll receive one that is totally inoperative, or at least drives full tilt in one direction soon as it's powered up. Also, you'll have to carry a bit more battery. The 900s have more appetite for electrons. Just depends on how much extra battery you carry if you're using hs 55 units now. ................ George K.

Raymond LeFlyr

My Feedback: (2)

I luv 'em! Better then the 55's and way, way better the the little red ones from Cox. And it ain't just me. Its a safe bet that they are the single most popular servo in our club - period. I'm the only small glow engine user in the group (of about 35) so the majority are in our combat models and almost every foamy.

Dave Wave

So what is the construction quality like? Is it close to the futaba servos (I have had good luck with them and found the construction quality to be good, but they can be a little $$$ in comparison)?

The Cox ones split in two when I pushed down trying to put an arm on the output. The splines on the output were of very poor quality and almost impossible to get the output arm on without the guts coming out the bottom...sigh

Thanks,


-Dave

alcarafa

HX900 are excellent servos and practically indestructible when you change gear to metal (look at link) infinitely better than Futaba - Hitec and more expensive ones.
Have not percieved any weakness at all , center well and speed is ooutstanding I have used them with all sort of planes up to .15


http://www.hobbycity.com/hobbycity/s...idproduct=6760

hllywdb

I've used them in 1/2A stuff and have had no issues. Way better than the HS-55's. I like the Futaba or GP B-8 servos in 15 size, or rudders in a 074 just for better torque, but like Rafa said, excellent servos, even the cases are better than the HS-55.

Dave Wave

Thanks for the info. I think I will get a set and report back.


-Dave

MJD

My Feedback: (1)

You almost have to form your own conclusions. You'll get opinions from "they're crap" to "they're the best". Anyone who owns a few that work well will say they are great, anyone who has had problems will say otherwise.Just like with engines

I was about to buy a bunch on a cohort's recommendation, but since that I have seen them strip on a single aileron on a .15 size model, while they have also held up fine in other circumstances. I wonder about consistency same as I do with anything priced so low it seems too good to be true. If HS-55's are so bad, I wonder why my HS-55's are still working perfectly with no deadband on a 125mph electric which I regularly snap roll at high speed? Yet I recently lost one by bumping the rudder on the ground on a foamy. My conclusion is that HS-55's are decent servos, but the downside is that they can't handle much shock - they are prone to shock on the geartrain.

I am now a convert to HS-65's for peppy 1/2A size models and HS-85's for stuff with a bit more stress. I might yet try the HXT900's on stuff in which I don't have a lot of time or money invested. But anything scratch built with 15-20 hours in the airframe I'll pass.

R/C Phile

To me, it's about having the right tool for the right job. The little Cox servos are just dandy as throttle servos and also do fine as rudder for lightweight models. The HXT900's can handle elevator and ailerons on probably up to .15 size plane.

On a plane that I have an expensive engine on or put a lot of time into building I'll probably spring for HS65HB's on Aileron / Elevator but I would still use the cheapies for rudder / throttle. Dave at Radical R/C also has those Dymond servos that have Coreless motors / and look to be of excellent quality while still being cheaper than the higher line Hitec's.

To test the waters I bought 10 HXT900's and so far, I have them installed as such :

36 inches wingspan 3D foamy, about 15 ounces flying weight

Aileron (1)
Elevator (1)

Little Extra Enya .09 powered, about 26 ounces flying weight

Aileron (2)
Rudder (1)

I only have about 1 dozen flights experience with them on the foamy and none so far with the Little Extra. They are definitely more consistent and precise than the HS55's as aileron servo on the foamy (No wobble after a fast roll) and the elevator has better "definition" as well which helps for hovering and harrier maneuvers.

The HXT900's ace in the hole is the coreless motor: They are faster / 40% or so stronger and center a lot better than the HS55's in fact, they are awfully close to the HS65HB if a little noisier and not quite as smooth (No Ball bearing)

Also, the casing is significantly better than both the HS55's / HS65HB's as the mounting ears are significantly thicker and Get This: They accept grommets ! which is a boon when dealing with glow vibration.

On the downside, The HXT's can draw more power when strained. Part of that depends on how smooth your mechanical setup is.


Here are the specs comparisons:

HXT900

Weight: 9g / 0.32oz
Speed : 0.12 sec/60(4.8V)
Torque : 1.6 kg-cm

HS55
Speed (4.8V): 0.17 sec/60° at no load
Stall Torque (4.8V): 15.27 oz-in. (1.1kg.cm)

HS65HB
Operating Speed (4.8V): 0.14sec/60° at no load
Stall Torque (4.8V): 25 oz/in. (1.8kg.cm)

From what I have seen the 3D electric heli guys rave about the HXT 900's and at 3 bucks a piece, just chunk the odd one that's no quite great..

See pics for build / gear comparisons

-Francois

eroc144

My Feedback: (1)

Control of my control surfaces is not an area where I'm willing to gamble, and once I lose faith in a servo it's all over...

I stopped using HS-55s for anything other than throttle many years ago - I fly at the larger end of 1/2A and for me they're just too delicate. I've had HS-65s get twitchy but never fail outright, and of course Hitec replaces them at no cost. I use the HXT900's in my foamies and have never had an issue, but the only time I used them in a glow model the elevator servo failed on the 3rd flight - the plane was a write-off.

I'll use the HXT900s in foamies and other "disposable" planes, but not on my performance planes. At least not yet...

EG

R/C Phile

How long ago was it when you had the HXT fail in flight? I have seen that some batches were less than great in the past. Also, according to Hobby King, there are different "grades" of HXT and the ones you find on ebay are not built to the same standards. Of course that could just be marketing cool-aid.

I'm willing to try mine on them on ailerons for the Little Extra (The elevator is an HS-65) . I'll keep a close eye on those..

R/C Phile

I just flew the Little Extra with the upgraded aileron / rudder servos : Holy Smokes !

The aileron response is razor sharp and the roll rate went from fast to dizzying.. The response is now even a little too sharp, I had to increase aileron Expo from 20% to 35% and I may add more later.

Not only are those servos stronger / quicker but somehow they have more travel with my flaperons setup. I had to enlarge the holes to allow for extra travel which made for crazy fast roll rate .

I just hope they continue to perform so well..

Pretty cool that they made my crazy Little Extra a little crazier