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Old May 09, 2012, 06:16 PM
Staggerflyer is offline
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Tama, Iowa USA
Joined Dec 2007
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Quote:
Originally Posted by Paul J. Harris View Post
Now that I have received the ARF kit, I am very impressed with the overall quality of this model. Before accomplishing any actual assembly, I need to determine how I am going to mount the battery and what servos I am going to use. I would like to switch to digital, metal gear Hitecs, as I have a programmer. However, I am pretty sure I would need to install CC's 20 Amp BEC Pro to handle six or seven digital servos going all at once. I wonder how the additional draw of digital servos will effect flight times using Gens Ace 5s5300? Any feedback on this subject greatly appreciated.

From what I understand, digital servos do draw a lot more than analogs. I do not have enough flightime recorded on any of my planes to know exactly how much time I have available. Have not run any to even near cut-off, yet, and am nearing the ten minute mark on a couple different ones. But, I would guess that you are going to be near that number with what you are planning.

As I understand it, Big Lacy put his series batteries in the forward cockpit to offset the additional weight of the Power 110 motor. Staggerflyer dropped his straight down behind the firewall by creating a hatch, and presumably, that worked well with the Rimfire 1.20 that I will probably use. I am working on a compromise that involves a 'hatch' cut in the 'floor' of the front cockpit with ramp that will slide the battery at an angle forward and down against the firewall. The CG of the battery will not be quite as far forward as Staggerflyer's installation, but he did feel that he was nose heavy. If I have to add weight to achieve balance I don't have a problem with that as I do not intend to fly this model 3D. I will post some pictures of this installation when I get a chance.

I am planning to use APP connectors (75 amp) on my 5s batteries and the ESC. Since this is my first venture into giant scale EP, I should probably build a Safety Plug from the connectors, but I am not familiar with accepted practice for wiring this. Presumably, it is just an interruption in the positive lead to the ESC? Correct. If using the onboard BEC then all power would be interrupted, but if using an external BEC, then the receiver and servos would be powered as soon as the battery is connected, but the ESC would not come online until the plug was installed? Just wire in the BEC behind the Safety plug, on the ESC side, so that lead does not recieve power till the plug is installed.

The safety plugs I use are made by MPI/MAXX. They are wired so the plug is on the positive line. However, it really is more correct to wire the plug in the negative line, as DC current actually flows FROM the negative TO the positive. This would eliminate the sparking on connection, as well as any electrons getting to the electronics until the plug is installed. (This is how all modern, ie 1985 or so, automobile electrical systems are wired now, to prolong switch and motor life. Same with sensors and computers in vehicles.)

Thanks for any help,

Paul
Read the red.
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