AR9100..Will I need power expander?
12-26-2008, 01:01 AM
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AR9100..Will I need power expander?
Hey Guys,
I am not very "up" on the modern power systems that a lot of people are running these days. It's been about 5 years since I've had a 33% plane and apparently that is an eternity for technology! Anyway, I am trying to determine the best setup for a 35% Pilot-RC Yak I am thinking about building. It will have 8 Hitec 7955's (2 per ail, 1 per elevator half, and 2 on rudder) plus a throttle servo. I am thinking either lipo or a123 batteries. I was looking at the Spektrum AR9100 "powersafe" receiver. Will that alone be a safe enough setup or should I run some sort of power expander? One thought I had was that if I want to run a smoke system or anything else, I would have no channels to plug into unless I "Y'ed" some of the ganged servos which is a "no no" right? Also, if I am going to run a power expander, is there any need for the more expensive powersafe Rx or will the standard JR R921 Rx be fine then? If I do run a power expander, which should I get? I am also going to ask this question in the smart fly forum. Thanks in advance for any help/suggestions!!
Todd
I am not very "up" on the modern power systems that a lot of people are running these days. It's been about 5 years since I've had a 33% plane and apparently that is an eternity for technology! Anyway, I am trying to determine the best setup for a 35% Pilot-RC Yak I am thinking about building. It will have 8 Hitec 7955's (2 per ail, 1 per elevator half, and 2 on rudder) plus a throttle servo. I am thinking either lipo or a123 batteries. I was looking at the Spektrum AR9100 "powersafe" receiver. Will that alone be a safe enough setup or should I run some sort of power expander? One thought I had was that if I want to run a smoke system or anything else, I would have no channels to plug into unless I "Y'ed" some of the ganged servos which is a "no no" right? Also, if I am going to run a power expander, is there any need for the more expensive powersafe Rx or will the standard JR R921 Rx be fine then? If I do run a power expander, which should I get? I am also going to ask this question in the smart fly forum. Thanks in advance for any help/suggestions!!
Todd
12-26-2008, 09:13 AM
#2
RE: AR9100..Will I need power expander?
Up to you which way you go....
There's always something of an argument when you ask about PE's and especially when it's for something smaller than a 40% bird. I subscribe to the theory that less is better where possible.
IF you decide on the AR9100/R922 rx, then you'll want to keep in mind that the current (no pun intended) limitation is the small servo connector leads. Those are good for about 4 amps continous with spike capability to about 6 amps is the generally accepted range. One can figure on about 1 amp of current draw for each 100 oz. of servo torque for setup purposes if you want to know what the system may be capable of pulling. If you check the specs on your servos, you'll see that is a pretty close estimate.
Some will argue the power system should be able to support the highest anticipated load, others will mention that the highest load will normally be brief and within the limits of a systems burst capability. One thing nice about it is that the Spektrum/JR rx's will tell you if you get a power brownout so you can change things afterward if necessary.
If you go to a PE then there is no need to run the PowerSafe rx's, just go with the AR9000/R921 rx's and they are even easier to mount on most PE's.
Oh, I would not "Y" anything on a 35% size aerobat. I do run Matchboxes on the ailerons of a 33% size model, but it does not have that big a servos in there either. I suppose one might make the argument that the aileron servos would never pull anywhere near the rated torque output of the 7955's and therefore would not need a 6 amp supply to each wing, or Matchboxes are capable of having a separate power lead to them if that is a concern.
JMHO, YMMV....[8D]
If you wanna look, here's a big thread on PE or not....
http://www.rcuniverse.com/forum/m_7999907/tm.htm
There's always something of an argument when you ask about PE's and especially when it's for something smaller than a 40% bird. I subscribe to the theory that less is better where possible.
IF you decide on the AR9100/R922 rx, then you'll want to keep in mind that the current (no pun intended) limitation is the small servo connector leads. Those are good for about 4 amps continous with spike capability to about 6 amps is the generally accepted range. One can figure on about 1 amp of current draw for each 100 oz. of servo torque for setup purposes if you want to know what the system may be capable of pulling. If you check the specs on your servos, you'll see that is a pretty close estimate.
Some will argue the power system should be able to support the highest anticipated load, others will mention that the highest load will normally be brief and within the limits of a systems burst capability. One thing nice about it is that the Spektrum/JR rx's will tell you if you get a power brownout so you can change things afterward if necessary.
If you go to a PE then there is no need to run the PowerSafe rx's, just go with the AR9000/R921 rx's and they are even easier to mount on most PE's.
Oh, I would not "Y" anything on a 35% size aerobat. I do run Matchboxes on the ailerons of a 33% size model, but it does not have that big a servos in there either. I suppose one might make the argument that the aileron servos would never pull anywhere near the rated torque output of the 7955's and therefore would not need a 6 amp supply to each wing, or Matchboxes are capable of having a separate power lead to them if that is a concern.
JMHO, YMMV....[8D]
If you wanna look, here's a big thread on PE or not....
http://www.rcuniverse.com/forum/m_7999907/tm.htm
