nute12

My Feedback: (14)

Have dual servos on each of my ailerons and rudder on my extra.
set the mechanical all up and got the geometry of em the same.
Being like i am i was worried about too much draw from them fighting each other thru the travel.
So i took a old extension and cut the + lead in the middle and hooked in my DVOM. I then put the extension between the batt and switch.
Hooked up the wing panel to the rx off a y cable.
fired it up and here is what i got for a reading
Idle: .026 amps.
run thru motion slow: .03-.05 amps
slam the stick: .140-.190 amps
these are hitec 5645 mg servos, brand new.
I guess my question is is this acceptable? am i testing em correctly?
Thanx in advance.
John

Zor

Hi John,

If I understand properly your posting, you have 4 servos working simultaneously on the ailerons.

When you say "idle . . .026 amps" that would be current used by the receiver and anything else but not the servos.

With a slow stick motion the differential is small and so is the current.
Assuming that by slamming the stick you just move the stickfrom neutral to full travelonly once.
You would havea higher differential anda corresponding higher current.

The value you read seem well within normalexpectancies.
Of coursethe servos do not have any opposite forceduring your test.

The current you measure while the sticks are moved are average. The peak currents would be much higher.

It is difficult to answer your question"am i testing em correctly?" .
If em (them) means testing the servos, youare observing that they move.
You are not testing their torque, their response speed or theiir backlash.
You are not testing their ability to re-center accurately.

If I am wrongwith the previous commentsthen I do not know how servos operate.
Let us see responses from other fellows.
I made similar tests here for current recently and posted the results.
I was using a single DS821 and was measuring the current for the servo only.

Happy New Year.

Zor

nute12

My Feedback: (14)

thanx zor, guess i could of been clearer, what i was testing for was equal travel thru the movement and the 2 servos fighting themselves and using excessive juice.. think I have it pretty close, after posting this i went back and unhooked one servo arm fron the aileron of each wing and tested again. I actually got a little higher numbers as the one servo was doing all the work on that surface. so i think i have it pretty close.

Zor

nute12,

Personally I would not install two servos on the same aileron.
I would split the aileron in two and have each half actuatedby its own servo.
Thus avoiding servos fighting each other and avoiding centering problems

Zor

BuschBarber

My Feedback: (2)

It is very common to use two or even 3 Aileron servos on an Aileron half for large aerobatic planes. Hitec Digital servos can be programmed, via an external programmer, so that all the servos are exactly matched. For other servos, both Digital and Analog, both Futaba and JR have a Matchbox type device that lets you set the Servo Direction, End Points, and Neutral position for up to 4 servos per channel. Either way, the servos will not fight one another.

There is no need to cut an Aileron half into parts. I know of no one who does this.

Some sport planes, like the Hangar 9 Ultra Stick, have separate Ailerons and Flaps, on each wing half, and they use mixing to combine the Flaps with the Ailerons to form Giant Ailerons, at the flip of a switch. You can also configure Butterfly, as well, to move Ailerons Up and Flaps Down for creative landing manuvers.

ww2birds

My Feedback: (14)

John,

I've set up a number of dual servo systems, and the numbers you post (30-50 ma when at rest) look very good, seems like you have done a great job matching the geometry. I presume that when you get the higher current when you slam the sticks, this is just for a moment while the surface moves, and then it settles back to the "normal" reading?

Dave

flatspinjim

My Feedback: (3)

Most big gas planes, 35% and bigger run 2 or 3 servos per aileron and 2 or more on the rudder. It's a common practice.

Nute, your setup sounds like it's very good. I'm not sure what kind of battery setup you're running but one way I like to check my servo setup is by checking my mah usage per flight. On my 35% planes I'm running 7 digital servos plus 1 analog servo for throttle. With 2 2300 A123 batteries I'm using 120 mah per 12 minute flight. On my 42% plane with 9 digitals and the same battery setup I'm using 200 mah per 12 minute flight.

nute12

My Feedback: (14)

yes it is, i thought it was ok, but this is my first time setting up a dual servo surface. just wanted to make sure.....I'm questioning everything LOL

Zor

It depends a lot on the style of flying; how much control is being used.

Zor

jooNorway

Sounds like you have done the job matching everything mechanical perfect
If you have the Hitec programmer adjust deadband for one of the servoes up to eg 5 thus reducing currrent even more.