Setting up a PAU 37% Ultimate and wanted to ask a question about the battery setup. I am running a futaba 2.4 rx with 8 digital servos, one of which being a Hitec 7950 servo and two analog servos for throttle and choke. I was planning on using two A123 batteries into two switches, into two separate RX channels. Is this going to be ok. Or do I need to get a smart fly power expander? This will be my first big plane so just making sure I don't screw anything up.


Thanks,

patrick

What kind of reciever you using? I've heard of some JR are set up for redundecy.....I personaly use smart-fly eq-6 on all my planes with the relion batteries. Never have had a issue.
Futaba 2.4 reciever as well...........

you Can do that with all of the Hitec optima RX's as I do I am using 2 a123 battery packs in my giant p47 one is plugged into the battery port on the rx and the other is using a y harness with the a 123 battery into one side and throttle servo into the other side with the male end into switch #2 and then into the rx ch3 and I also use a good 4.8 v 2300 mah nimh on a separate switch for the engine cdi . with that set you will have no problems

Phantom driver the RX will be a 14 channel 2.4 ghz futaba (6014). I am hoping this should be fine to handle the load I am putting on it as this is the same type of setup I use in all my jets.

Okay here's the deal.

The orange T-shirt crowd will tell you the've done it without issue.

Bax (Futaba service in the USA at Hobby Services) will tell you the buss in those rx's is only good to 8 amps. He's also noted in a couple of threads on the Futaba support forum here that he thinks the 35 amp continous 50 amp burst capability of the 9 channel and above Spektrum/JR 2.4GHz rx's is a lie....[X(]

You can use a rule of thumb that 100oz. of torque will require 1 amp of power and that will be very close to actual servo specs. Be aware that if a servo binds up or something it can exceed that current draw by 50%.

Next issue is that even the best servo leads with at least 22g. wire and gold plated connectors can only handle about 4 amps continous and burst to 6 amps for short periods with cheap leads or connectors only supporting about half that load, the 7950 can pull 4 amps all by itself and you've used half the capacity of the rx buss with one servo....[X(]

I'd put a PE in it but that's my personal opinion....

I setting my Waco up with the duraliteflight system power distribution system. The system gives dual everything for the ultimate in reliability and depending on which duralight you purchase servo match box capabilities are part of the system (multible servos on a flight surface and seperate gear door sequencing with retracts). Jack Price at duralight is very helpful web site is: duraliteflightsystems.com

Jim<br type="_moz" />