Greetings folks. I am getting ready to set up the electronics for my Extra. Right now what I have planned is either the sbus setup where it all just gets plugged into the Futaba 14 channel receiver vis the sbus cable or ill just run all servos direct into the 14 channel receiver so I don't have to worry about the capacitor deal. I am running 2 7200 mah batteries and a Tech Aero on the ignition and using the futaba a-700 servos.

Questions I have are:

Is there any reason to use sbus over direct connecting the servos?

Can I still use two receivers? If so is it worth it and how will that work if direct connected or with sbus?

Do I need a servo programmer? If so what exactly do I do with it?

I'm getting back into large scale imac planes and things have changed since I was last here so I am really looking for how we do this today. If there is a "default" setup people use these days that would be great to know!

Thanks for you help!

I run Futaba stuff from the rx’s to the servos are all sbus capable. I couldn’t convince myself that one plug in for everything was ok. After setting up a plane with two rx’s I went with the XPS 24 and am very pleased I did. Battery redundancy and receiver redundancy with a bec and servo auto match.

Is there any reason to use sbus over direct connecting the servos?

Reasons to use SBus:

• You don't have enough ports on the receiver and want to use and SBus hub or channel expander to get access to more channels
• To simplify the wiring so that you don't have dozens of long runs from the receiver to each servo

Can I still use two receivers? If so is it worth it and how will that work if direct connected or with sbus?

Yes you can, but its not mandatory. There are 2 reasons to use dual receivers:

• To get access to more channels without using SBus (a pair of 7008s can be used this way, 1 provides ch1-8, the other provides ch9-16)
• To gain partial redundancy in case one receiver fails... Think of the old days when guys would put the right hand ailerons and elevators on one receiver and the left on the other.

Do I need a servo programmer? If so what exactly do I do with it?

If you are going to use SBus, yes you need a programmer to at least assign each servo to the channel you want it to respond to.

If you are not using SBus, the programmer is optional, but it can be used to match neutrals, set end points, etc - the same way the Hitec programmer is used.

Certain Futaba TX's including the 16, 18sz, 18mz etc include a programmer built in.


Other notes:
If you use SBus and gang a bunch of servos on hubs, make sure you have planned for good power distribution. Each A700 can use a few amps when stalled, so if you gang them you can be overloading that single SBus lead with more current than it can take. I'm using some of hose 6 port SBus hubs on one build and I'm attaching3-4 servos, the SBus lead and leaving the 6th port open for an additional power feed.

The capacitor that Futaba supplies is intended to help prevent glitches if the servos pull short duration current spikes that cause voltage sag. Switching from SBus to individual servo wiring isn't going to magically solve this if the burst load is more than your batteries can supply. If you have any doubt just use the caps, not much downside.

You should have no fear of using sbus in a 40% plane. I have had my Carden pro since 2013 and is was setup using 2 7008 rx’s and BLS 172sb servos. I have well over 1000 flights on this system with zero issues. Pay no mind to all those that speculate without actual working knowledge of the system. Having said that. If you would use the A700’s, I would definitely make sure you are running individually power to your main sbus blocks for the tail servos and wings. Not to mention the inline capacitors that Futaba sells.

Originally Posted by eheliflyer

You should have no fear of using sbus in a 40% plane. I have had my Carden pro since 2013 and is was setup using 2 7008 rx’s and BLS 172sb servos. I have well over 1000 flights on this system with zero issues. Pay no mind to all those that speculate without actual working knowledge of the system. Having said that. If you would use the A700’s, I would definitely make sure you are running individually power to your main sbus blocks for the tail servos and wings. Not to mention the inline capacitors that Futaba sells.

Hey Eheli, I can see your reasoning but for me and me only, I prefer each servo in it's own port. If One comes out of the receiver, then I lose one servo. If the sbus cable comes out.....well.....
Not to mention it just seems like I'm doing something wrong unless I do it the way I dunnit for the past 43 years...…
and finally, I refuse to buy those little dealios that I'd need in various places in my plane to run sbus. Other than that, I love sbus like crazy!!

Originally Posted by jlc

I run Futaba stuff from the rx’s to the servos are all sbus capable. I couldn’t convince myself that one plug in for everything was ok. After setting up a plane with two rx’s I went with the XPS 24 and am very pleased I did. Battery redundancy and receiver redundancy with a bec and servo auto match.

^^^^^^^^

Tha is so much for the info guys. I’m learning this stuff slowly.

I can definitely understand your concern, as I had many concerns as well. I do have a certain amount of redundancy built in to my setup, like two sbus extensions to the tail.


Not to mention it just seems like I'm doing something wrong unless I do it the way I dunnit for the past 43 years...…
and finally, I refuse to buy those little dealios that I'd need in various places in my plane to run sbus. Other than that, I love sbus like crazy!![/QUOTE]

If you can find the Futaba YouTube channel, there are a bunch of nice videos with Frank Noll That show sbus setup examples.

I've built 2 of the Version 4 EF 125" Extras. I fly JR DMSS and even though I could go X Bus It doesn't get any simpler than a 11Ch Powerbuss receiver and a Tech Aero IBEC. 2 - 6400 MA Li Ion batteries for power. 2 servos on each aileron, 2 on the rudder in the tail and 1 on each elevator, and of course a servo on the throttle. I only burn up about 450 MA a flight. 170cc and RE3 Pipes. With the Rudder servos in the tail you will work hard to balance it without a heavy prop and spinner combo. My batteries are just behind the firewall and it will fly a long way on a 45 upline inverted before starting a slow arc to the canopy. Actually have a single JR 915 in oz brushless on the rudder currently. Getting ready to replace my pretty Red Falcon spinner with something a little heavier to move the balance a little farther forward.