WRX

My Feedback: (1)

Ok I have a few GWS Pico servos, but Now that my HERR AT-6 Texan is done I wondering if these sub-micro survos have enough strength to hold my control surfaces. Anyone have any suggestions on cheap survos for my texan?

fireman7875

My Feedback: (7)

I don't know about the GWS Picos as I haven't ever used any. Just guessing, that seems a wee bit small to me. I typically use Hitec HS-81's (or equivalent) in anything .049 size and larger. Your AT-6 would fall into that category. I have heard of some guys using HS-55's on their 1/2a stuff but if I'm not mistaken, even these are a little more powerful than the GWS picos.

RYANO218

I dont think that those pico servos would quite have enough torque for a 1/2a.

DesignMan

You could probably get away with one for throttle, one for each aileron (then mix for flaps) and use slightly larger servos for elevator and rudder.

Uncas

My Feedback: (1)

I use an HS-50 on my Dandy GT (electric) ailerons and it does fine. I think it is close to a pico.

Larry Driskill

I have HS-55s on my 1/2A LiteHawks. The speed and load probably has them a bit stressed at times, but I have not had any trouble with them.

SST

My Feedback: (2)

Check out the Dymond D-200. Same size as the HS81, but much more substantial power.

MikeSell

My Feedback: (2)

The Herr AT6 at my house has 4 Dymond D200s in it. I have used the Dymond D200 in several planes for several years without a problem (34 oz/in). The other day one stripped its gears because of surface flutter. It was a large aileron on a .40 size plane moving quite fast and I gave the surface too much mechanical advantage over the servo. I bought new gear sets for $3.50 each and I'm back in business. (Don't worry I learned my lesson on the linkage)
Right now they have a special on their D60 for $19.99 ea. (.3oz 24oz/in) I use these in my lighter 1/2a planes and they have served me well.

BMatthews

Let's stop guessing....

http://www.csd.net/~cgadd/eflight/calcs_servo.htm

For a 1x10 elevator flying at 60 mph and 20 degree max one way I get a measely 0.624 in-oz required.

For a rudder 2 x 5 and 30 degrees I get 2.85 in-oz needed.

1 x 18 and 30 degree aileron (one) I get 2.6 in-oz needed.

Even at 100 mph this aileron only needs 7.2 in-oz.

So the 11 inch ounce picos or HS50's would be seem to be fine. You'll get MUCH more resistance in your hinges and any bad pushrod routing apparently so be sure to take the time to make them very free in operation and floppy in the hinges. Also you'll really want to watch out for the hanger handling. The small servos are much more prone to gear damage through bad handling. Always do a thourough preflight and LISTEN to the servos to detect any changes or rough running.

To be safe and not run the servos close to their stall torque I would never load a servo beyond it's 50% point.

Bipe Flyer

I just ran the same numbers through the calculator at this link.
http://pages.sbcglobal.net/limeybob/Servotorque1.html

It says that 1.715 Oz-In is required for a 1X10 elevator at 60mph.
A rudder 2 x 5 at 30 degrees =5.01 Oz-In.
1 X 18 at 30 degrees = 4.513 Oz-In and at 100 mph = 12.536 Oz-In.

On the calculator you posted, I notice that if I set the degrees for the servo deflection the same as the control surface deflection the results are the same as on the calc I posted.

I guess this illustrates why it is good to use the maximum servo delection whenever possible.

BMatthews

So it sounds like your link is the actual surface torque required rather than the torque of the servo. Yeah, the mechanical system leverage should be factored in if you're looking for the SERVO torque needed.

It's good to know that the two calculators at least agree on the air load algorithm even if the results are presented differently.

fritzke

My Feedback: (1)

I like the HS 80-81's too, pretty light, decent torque, cheap ($18), pretty easy to find.
Even work in my larger .020 planes.
Dave

MikeSell

My Feedback: (2)

My sons SAE Aerodesign entry this year used HS 81s. (15' span, lifted 52# gross wt) The slow performance allowed small servos to move large surfaces. The similar practice plane I built used HS 85s for the ailerons. In conversations at the field I was told several times of individuals waiting for replacement gear sets for their HS 81s. At the competetion my son had to replace a gear set too. I contend if you plan on using the HS81s that you get the metal gear version so it will survive the occasional bump or bash. The hs 85 has more torque but still a fragile gearset. I opted for the metal gear version of it also.
The Dymond is rated at no more torque than the hitec but has a sturdier gearset and better holding power.

Japanman

I have ordered a couple of cirrus 4.4 and 5.4gram servos- I`ll let you guys know what I think of them.
One thing that I think is important for servos that I seldom see discussed is the current draw of servos- I favour my old futaba metal gear servos (what number are they? same size as hs80 anyway** went and chacked- S102**) over the hs80 as they use far less current- Having flown a lot of slope soaring foam planes I found that the futaba servo would get sluggish as the battery got dangerously flat- but I could still fly for long enough to land- where as the hs80 puts too much load on the battery, dropping the volatge so much that the rec just stops dead.... as does your plane... So for this reason I favour servos that are not too power hungry. My JR371s seem very good in this respect too.
Call me chicken but I like to think that If I have stuffed up my battery charge somehow, I will get a warning from the servos before the plane goes deadstick.

Just my 2Cents worth

J.M

mclintock

My Feedback: (3)

Hey do ball bearing servos really make much diff in half-a? They weigh and cost more, but what really do you gain?
Do they last longer or something? Less slop?

I was gonna buy some of those generic things from ebay, but i was wondering what would happen if, I mean when i crash and strip the gears. Toss the generic? The gws gears are two bucks.. so maybe it's worth the extra three for gws over the 'oem 99% gws' ebay things..

Here is a site that has gws servos at what seems good prices, neatly listed..

[link=http://www.buygws.com/servo.htm]gws servo page[/link]

MikeSell

My Feedback: (2)

The OEM generic servos on that auction site are JUNK. A few people get them to work in the right conditions but the ones I bought don't work with some receivers and don't work with 6v battery packs. They are low torque servos and spin easily if the surface is bumped.
I think that stronger gears and higher torque ratings are more important than ball bearings. The ball bearing servos use the ball bearing to support the output shaft while most micro servos don't even have a bushing, just a hole in the case.

Andrew

I've noticed that Hitec has an HS-56HB now available -- 2 gm. heavier than the HS-55 with 2 oz-in less torque, ballbearing and $6.00 more. It does have mounting flanges that allow upright or flat installation and a Karbonite gear set. I don't use HS-55 on surfaces (throttle only), but I don't have anything smaller than .061's. The gear sets in the HS-55's are so small that the teeth are tiny -- and I feel comfortable with a little more beef.

I agree with Mike that I like a more robust gear set -- I have some HS-81MG's -- purchased after stripping the nylon versions. I would like to see the HS-81's come out with a new composite gear set -- supposedly the Karbonite is almost wear free and up to 4 times the strength of nylon. With the HS-81 being used on larger planes, I would have thought that it would have been one of first candidates for composite gears. Guess Hitec thought the production metal gear set was OK for the time being.

the "other" Andrew

Japanman

Wow! More expensive, heavier, and less power!! If only engine manufacturers would get in on this

...But seriously ...this makes me wonder if the karbonite gearset might fit the hs55...

JM

Andrew

Hey JM --

I had emailed Hitec's service dept. regarding the substitution of gearsets. Here's the word from the horse's ... errr, Hitec's mouth:

*****************

No the gear set for the HS-56 will not work in the HS-55. And there are
no planes on doing a upgrade gear set for the HS-55 to Karbonite.

Thank you,

Martin Salgado
Customer Service Department
Hitec RCD Inc.
Phone # ( 858 ) 748-8440
Fax # ( 858 ) 859-2618

*****************

the "other" Andrew

Bipe Flyer

It looks like Hitec sacrificed torque for speed when going to the HS-56. It also has side mounting tabs for wing installation.

HS-55
Motor Type : 3 Pole Ferrite
Bearing Type : None


English Metric
Torque 4.8/6.0v : 15 / 18 oz 1.1 / 1.3 kg.
Speed 4.8/6.0v : 0.17 / 0.14 second
Size : .9"x .5"x .9" 23 x 12 x 24mm
Weight : 0.28 oz. 8 g.




HS-56
Motor Type : 3 Pole Ferrite
Bearing Type : Top Ball Bearing


English Metric
Torque 4.8/6.0v : 14 / 17 oz 1.0 / 1.2 kg.
Speed 4.8/6.0v : 0.12 / 0.10 second
Size : .9"x .5"x .9" 23 x 12 x 24mm
Weight : 0.37 oz. 10.7 g

Japanman

It would be good to compare the gearsets side by side- if only the output shaft and second gear would fit that would make it a worthwhile swap.

J.M