ORIGINAL: curtusua-RCU
I plan to fly it in a "sport" fashion, (as I am certainly no accomplished aerobatic pilot!) and using the "rule of thumb" I guestimate that I will need about 100 watts/lb.
So, 600 watts needed and probably a 40 amp motor (I'm thinking AXI 4120/14) leaves me in need of a 15 volt system.
Am I right so far? I was thinking of a 4S LiPo (600/40=15, 15/3.7=~4S) pack but am unsure about the capacity of the pack I will need.
I was thinking of using four of the new Kokam 2S2100's (20C) packs and rigging a 4S4P system. What do you all think? Or perhaps two of TP's 3S2P 4200's in parallel?
The other question I have has to do with the Kokam series and their parallel connector boards. Will they be able to handle these batteries in the configuration I am thinking? I seem to have read somewhere that 1500 mAh is their max recommended rating but I'm not sure!
Curt Hughes
Curt,
100 watts/lb is a good starting point, but for Sport is more than you will truly need. It is however, my bottom line on any conversion I do, no matter what type of plane it is.
The 4120/14 on a 4S is a good setup and one I have considered myself for this plane.
On batteries:
I have lots of experience with TP's and only experience with the older C kokams. However, from what I have read, they all more or less perform within the specs. So choose one based on price. You are not going to need a 4P for this conversion since the amps will not reach that high. Even on a 10c pack, a 3P is rated at 60 continuous. And since you are looking at ~40 amps, you have some room to play with. I typically will not drop below a 3P for three reasons.... I like the extra flight times given the added mah... It gives me extra headroom in the event I add another plane to my collection which now requires more amp usuage....and it is good to have the extra weight for balancing a model. I would go with a 4S3P TP 6000 or 4S3P Kokam pack. I also recommend that for purposes of obtaining CG, you use two 2S3P's and connect them in Series via the conector board or a simple Series plug that can be soldered together very easily. Just charge them seperately before connecting in series.
-Mike