flyinrazrback

My Feedback: (69)

Have a question that a friend of mine and I are curious about. How much load can a regular rx, ie futaba 149DP or the top of line JR pcm take. I mean say the hangar nine ultimate has 4 servos per one channel for the ailerons, 4 for the other side, 4 rudder, and 2 elevator. The issue is, say in a snaproll where all 3 control surfaces are maxed out, is there too much draw from a single receiver to power the servos? We are thinking on using one receiver and no matchboxes. Possibly using something like an I4C system to seperate the battery loads. Just have heard stories of people running several digital servos from one receiver and the electrical bus in the rx fail because of too much amps/volts (not sure exactly) Maybe this is not understandable or needs clarity on what I am asking. Any info would be appreciated.

WreckRman2

My Feedback: (5)

This doesn't exactly answer your question but anytime you have an airplane large enough that each surface has at least two servos it's a good idea to go ahead and use two receivers. This will not only separate the load per receiver but it now gives you redundant control in case one receiver fails. Along with that second receiver you'd use a second battery and a second switch too.

Flyfalcons

The magic number I have heard is 10 servos per receiver.

Lynx

The power for the servo's is shared on a power bus inside the receiver housing, the thickness of that piece of metal determines how much current it can pass through, so it'll vary from receiver to receiver. And I wouldn't recommend anyone run that many servo's on a single receiver's shared battery. If you need that much power for your servo's to increase reliability and decrease problems you should probably power the receiver from a different battery as the servo's otherwise if you get too much of a current hit on the servo's all at once your receiver will momentarily black out.

Pilotsmoe

The limit on most rx's power bus is about 2 amps.

flyinrazrback

My Feedback: (69)

Thanks for the info, I usually run one receiver and 2 batteries (lithium with regulators) and 2 switches. This is my first plane that has 13 servos, so probably best to go with an isolator system such as I4C.

WreckRman2

My Feedback: (5)

If your going to run 2 batteries and 2 switches you might as well run dual recievers and make it a true redundant system. That is if you want to spend the extra money on the second rx.


At least with 2 rx's you won't need all the Y extensions. You can run one elevator servo to one rx and the other servo to the other rx. Same with rudder and ailerons giving you a true redundant system in case an rx fails.

flyinrazrback

My Feedback: (69)

The airplane its going in has 3 servos per aileron, 2 on the rudder, and 2 in each elevator half, what is the best recommended setup for 2 rx?

WreckRman2

My Feedback: (5)

Well the key point is to run one servo from each surface to each rx.

So for example with 2 servos per elevator half you would take one servo on each half and run them to rx1 and the other servos on each half and run them into rx2.

Being that your using 3 servos per aileron half you might run one servo to rx1 and the other 2 servos to rx2 and the same on the other side.

This way if one rx, battery or switch fails you will still have the other half powering at least one servo per surface.

The main purpose with a redundant system is that no matter what if something fails whether it's a rx, battery, switch, etc you will STILL have enough control to land the plane safely. It's usually only done with big airplanes because if you don't have at least two servos per surface you can't get true redundancy.

JohnVH

My Feedback: (38)

In my sukhoi I have 10 servo's, of those 5 are digital, and two switches and two batteries and Ive run this setup for 51 flights now and not one problem.

If your worried about RX power, or lack of, use matchbox's with batteries plugged into them, I have 3 matchbox's in my sukhoi but the batt's are in the RX.

frequent flyer

My Feedback: (6)

If you have two recievers with control surfaces split between to rx's and one fails does that mean half of the planes surfaces are dead?

WreckRman2

My Feedback: (5)

If done correctly one servo per surface could stop working but the other servo should still have enough power to move the surface enough for you to land and save the model. Remember your not putting right aileron and right elevator on one reciever, you'd put one servo from EACH surface on one rx and the other servo on the 2nd rx.

frequent flyer

My Feedback: (6)

Is there a site or source for diagrams of set ups for 35% planes? is one servo that has 125oz. torque enough for one aileron? I bought a number of these 1/4 scale servos because many of the planes that I built from show only one per @ 70 oz. plus. I see that almost all of the planes that I see guys flying have many small servos instead, why?

WreckRman2

My Feedback: (5)

Weight and redundancy. One 1/4 scale servos weigh as much as 3 standard servos and most likely if one of those servos fail the other one(s) will still power the surface.