vertical grimmace

My Feedback: (1)

So now after all of these years, what is the verdict on using Hitec Karbonite geared servos with a gas engine? I have an Ultimate biplane I want to install 4 of the older digital karbonite geared servos in. It has a DL 50 engine. Has anyone experienced a failure do to vibration?

A.T.

Not recommended for use with anypetrolmotors, especially of that size.
For best information refer to the specifications for each servo under consideration.
Hitec Servo - FAQ
Previous similar thread

Alan T.
Alan's Hobby, Model & RC FAQ Web Links

vertical grimmace

My Feedback: (1)

Kind of sucks they offer so many Karbonite geared servos, with really god stats, but they are not useable with gas engines. Kind of a shame.

TimBle

are the Hitec gears too brittle?

A.T.

Would not say they are "Brittle" as less likely than the stanard nylon/plastic gears to shear,
they will as in the same manner as all other similar materieals when subject to
sudden shock loads or vibration.

Karboniote Gear Train
Found in all the "HD" (Heavy-Duty) and "HB" (Heavy-Duty Ball Bearing) servos.
"Karbonite" gears are four times stronger than our standard nylon gears and offer virtually ZERO wear;
even after 250,000 cycles when tested!

HS-5485HB
Features;
Applications: Heli's and Aircraft up to 72” or up to 12lbs when using just one servo per control surface.
Note: Be aware that high vibration gas (not glow) engines combined with large control surfaces and large throws
(3D models) can put undue strain on the gears.
Metal geared servos are recommended for these applications even if under 12lbs.]

refer charts under
<dt>Servo - Horn Arm Spline Count and Inter Brand Compatibility

Alan T.
Alan's Hobby, Model & RC FAQ Web Links</dt>

TimBle

so if they're better than nylon and nylon is adequate for use in Gassers applications, why is karbonite unsuitable?

s3nfo

My Feedback: (14)

And the application you quoted specifies 3D aircraft with large control surfaces, not all gassers.

1320Fastback

Isnt Karbonite not flexible.

So a nylon gear in a gasser would have a little give but Not break, and a Karbonite gear would have no give and shear teeth.

I think it's the constant heavy vibrations that would destroy the Karbonite gears.

TimBle

karbonite is nylon 66 with carbon filler and I beleive a lower percentage of Molybdenum disulphide than vesconite.

gofast53

Ugly Stick 60 with a DLE20 gasser and std cheap futaba servos with nylon gears. Has done over 100 flights and to date no problems. But I would not recommend using them on anything larger and more expensive, especially where there is a lot of aerobatics involved. Orignal setup was with an OS .61 and which had more vibration than the DLE.
I use to race RC gas boats and found that the karbonite gears were not as resilient as the nylon ones when used for the rudder.

Zeeb

My Feedback: (41)

Hitec has maintained that the Karbonite geared servos are not to be used on gassers, models with over a 72" wing span or a weight over 12lbs. virtually since those servos came out.

If you "guys" want to ignore the manufacturer's recommendations then go for it but speculating here or relating stories of how you've successfully ignored the recommendations does not change them.

dant-RCU

My Feedback: (3)

+1

BarracudaHockey

My Feedback: (11)

What Zeeb said

TimBle

THanks Zeeb, I am trying to understand why Hitec does not recommend Karbonite gears with Over 72" span gassers. What is the science behind their fear.

snuts

When dealing with people who will try and do the most with the least. It is always best to suggest limits

Hope this helps,
-Snuts-

Pippin

Is it wing span and weight that sets the limits or engine power? Anyone who would put the servos in a 30cc glow powered model?

TimBle

There are folk flying 50cc with analogue high torque nylon geared servo's. They have not fallen from the sky yet.

rlmcnii

My Feedback: (3)

I am aware of HiTec's recommendations for the use of their servos with karbonite gears: one servo per surface per 12 pounds of airframe weight and no usage in gassers. WHY do they manufacture, and sell, something like the 7975HB?? It is a 144 in./oz. servo. Just right for a 10 pound .60 glow machine!!! One wonders.

snuts

And fast at .10sec @ 6V. Perfect for 15lb, 147inch glider elevator. There is more than gas & glow in the servo world

-Snuts-

TimBle

so the servos are high load capable but cannot be used on a gasser....

snuts

Sounds like metal gear servo's would work for you.
I use both metal, and nylon gear servo's in my gassers, depending on application. Hell I even use metal gear servo's in my gliders. After experiancing hanger rash on rudders, all metal gear rudder servo's.

Hope this helps

-Snuts-

rlmcnii

My Feedback: (3)

Never thought of gliders! Enlightenment helps. Thanks

BuschBarber

My Feedback: (2)

I have 20lb Electrics and there are 40lb Electrics at our field.

rlmcnii

My Feedback: (3)

The one servo per surface per 12 pounds of airframe weight still applies?

BuschBarber

My Feedback: (2)

I agree. I use Metal Gear servos on all my Gas, Glow, and Electric aircraft over 10lbs. I was just responding to the statement that there was more than Gas and Glow aircraft out there.