Servo load and BEC

[SnowDog]

I've got a system where I have 4 digital servos with the following specs:

Brand/Model: Solar/D771
Speed
@ 6.0v0.1Speed
@ 7.4v0.08Torque (oz./in)

Torque (oz./in)
6.0v 189.04
7.4v 214.06


I don't see any information on current draw and I have not hooked up an amp meter (yet).

These servos are being powered from a 2S 40C 3300mah Life battery through a BEC set to 6V output (since my RX cannot handle more than 6V). This BEC specifies a 6A continuous output current with a 10amp burst.

I had a friend fly the plane using this configuration and he complained at two differnt times that he thought the ailerons were not responding, but they came back. He landed the plane and told me he thought the servos were bad.

I've been flying the plane in this configuration and have not noticed the issue, although my friend is a much better pilot than I am and was definitely flying the plane harder than I do.

I'm looking for some input on the configuration...are the servos possibly drawing more amps than the BEC can provide? I will double check for binding but I don't think that is an issue. Any thoughts or ideas are appreciated.

 

[Capt.Roll]

I've tried the D771's and didn't care for them, too much play in the servo movement around center position. Used them for ailerons during the maiden flight of my 50cc Extra 300. Lot's of flutter on the control surfaces, visible enough that I had several other pilots suggest I land and check the plane for anything that may have been loose. Did so, nothing loose, and took it up for another flight and had same issue.

Took the plane home and changed the servos to Savox 1256TG and flight tested the Extra the next morning, issue was gone.

I've had good results with the D770 and D772 servos..........gear train doesn't seem to be quiet as sloppy. I'm flying my 3DHS 71" Slick with the 772's (rudder & elevator) and 770's on the ailerons and the plane performs just fine to me. I'm certainly not a "world class" pilot so a better pilot may think the servos are a POS and make the plane fly like a turd.

With no load operation the Solar's don't pull more than 0.3-0.4 amps. If you were to stall the servos they could easily pull 3 to 4 amps each which could cause an issue with your BEC.

If your friend is used to flying with servos that are better quality/performance than the Solar's I can understand how he may think the servos are unresponsive. TX/RX latency can be a factor as well as how much EXPO you have setup in your TX.

 

[wedoitall]

ive been putting my digi servos on an amp meter a lot here lately. especially when I first use them. I record the amps with servo horns/linkages uninstalled, servo at idle. then I record them the same configuration while moving the servo via Tx. then I installed them on plane and hook up linkages and record movement both ways and pay attention to readings inbetween both endpoints.

I just made up some servo extensions with ec3 connectors to hook into my WattsUp wattmeter. Im sure its not the most accurate amp meter but im confident that it will let me know if somethings binding or not right.