Thursday, September 29, 2011

Savox SH-0257MG Servo Rundown

Savox SH-0257MG
I’ve been using Savox Servos in all of my planes for almost a year now, and they have been completely incredible from start to finish. My servo of choice for all surfaces on my Extreme Flight 48” EXP series of planes has been the SH-0255MG. This servo provides 54oz/in of torque, and is an all around tough servo. I’ve decided to mix it up a bit and see if I can find a better combination, and I think I found the best yet!
I decided to go ahead and get three of the Savox SH-0257MG servos for the ailerons and the rudder. Why? Well, Extreme Flight recommends the Hitec HS-65MG servos for the surfaces. The HS-65MG provides 31oz/in of torque and 0.11seconds speed. The SH-0257MG servos by Savox provide the same amount of torque, 31oz/in, only at a faster speed of 0.09seconds! That seemingly miniscule difference in speed may not seem like much, but when you are doing advanced precision and 3D maneuvers, you can feel the difference.

Also, the Savox SH-0257MG is digital, has an aluminum case, and still costs less than the Digital Hitec HS-5065MG… which still isn’t as fast. And for the elevator, of course I went with my trusty SH-0255MG servo which provides the torque needed to swing the big elevator up and down without blowback, or the need to widen the servo mounting hole like you would with the Hitec HS-85MG… plus it’s faster.

For a motor, I went with the Motrolfly 2820-750 with 680kv. This thing running on 4S batteries and a 14x7E APC propeller has an insane amount of power, torque, and plenty of vectored thrust. The big prop provides plenty of thrust during post-stall maneuvers to enhance control authority and precision, and also has tons of power when it comes time to rip out of a hover! It will go from a hover a few inches off the ground to out of sight in a matter of seconds!

Flight Review
As soon as I took off I could notice the difference. The SH-0257MG servos are wicked fast and insanely precise! Super swift movements mixed with digital precision really make for a great servo. Also, the SH-0255MG in the elevator kept up quite nicely while using Extreme Flight’s extended servo arm . It had tons of torque, an insane amount of throw, and I really felt confident because everything was so solid and locked in.

The Motrolfly had the Edge off the ground in just a few feet and shooting towards the clouds with ease. Plenty of torque and thrust from the big 14x7 prop keeps me in complete control in all aspects of flight; and when I need a boost of power to get me out a too low, too slow situation, it has the reserve right there waiting and really comes through. The motor pulls about 45 amps on 4S with the 14x7E and spins about 8300RPM’s… plenty of thrust on a 3.5 pound airplane!

Wrap Up
All in all, I think this is truly the best setup I've tried yet for this airplane. Now dim the lights, cue the music, sit back, relax, and enjoy!


Dimensions(mm): 22.8X12.0X25.4
Weight(g): 14.0
Speed(@4.8V sec/60): .13
Torque(@4.8V oz-in): 25.0
Speed(@6.0V sec/60): .09
Torque(@6.0V oz-in): 30.6
Gear: Metal
Bearing: 1BB
Case: Aluminum
21 Tooth Spline

--Tom K.

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