.40 size profile electrics <nudgeing BH>

well I would go LiPo, and double my current largest pack 12C 3s2p tanic 2500s to 6s2p.

ok let me translate that: On my biggest electric at the moment ~ 35oz auw, with a 5000mah battery that kicks out 11.1 volts and can withstand up to 60 amps. actually on the motor I run now, I use more like 30 amps, and get about 310watts, 150+ per pound. at 30 amps it would take like 10 minutes of constant full throttle to drain the battery. I get about 25 minutes of good aerobatic flight off of it.

with that as my time goal per battery pack - 10minutes full throttle, or 6C max, it means I can get 3.2x6x(capacity in mAh divided by 100) watts PER CELL from a pack of those cells when discharged around 6C. so a tanic 2500 would give 45watts at this level and actually 90 watts at max discharge. so go back to 150 to 200 watts per pound as a yardstick for extreme performance, and figure what you want your final AUW to be. 40 size? about 4, 4.5 pounds. so we want at least 600W and perhaps more like 800w. that means 12-16 of these 2500 Lipos at a low discharge-long flight time rate, or 8-10 at a higher rate. remember that the cells are like 1 ounce a piece or so.

now that you have a target cell count, decide how you want your pack set up. it's simple math: XsYp is X * Y = Z cells. so 12 cells could be a 2s6p pack, a 3s4p, a 4s3p or a 6s2p. there's a couple of pluses and minuses here - even numbered series packs can be made up of multiple packs of the same parallel (total capacity) but not vice versa. 2s isnt really used that much, anything over 3s can't use a BEC esc - needs either a separate BEC or a receiver battery, but also I've heard that high-voltage is more efficient than high-current. most field chargers wont charge more than 3s, but you could break a 4s in half and use two chargers.

so my plan is to use a 3s2p pack for a couple of two-pound size planes, and then combine 2 of them to make a 6s2p pack for one larger plane. an added benefit is that then i can charge the larger pack in halves. then If I wanted a 60size I could scale up to 9s2p, and so forth.

its not as easy to go from 3s2p to 3s4p because you need to have all the series packs closely matched in voltage in order to evenly discharge them.

dude, i am soooo wasted. I'll post again about motors or something.

-barrett

And I am about to whip out my first 40 sized profile, but I have to plug the 25 sized plane.

25 size is a pretty nice size to convert, not so expensive to put you in the poor house, easy to get some stunning performance, and will run on 3S1P packs.

That's the great part. You can spend as little or as much on a motor as you want, but the larger speed controllers and large battery packs are the killers dollar wise no matter what you drop on a motor. So having a plane that flys on a single 3S1P 2500 pack is not that much of a sticker shock.

On the E Taco Yak at Tulsa, we flew it pretty much as often as the pin was available. And the packs are $90 ea. This might seem like a lot, but for the same investment as a couple of 40 sized packs, I have 7 to rotate through. I can have one flying, one cooling off, 2 on the chargers, and 3 at the ready. At 15+ minutes per flight, you can flat get some stick time.

I've only got a couple of packs for my 40 sized conversion, I want to see if the cell count is going to provide the performance I'm looking for before I drop the $$$ to load up on packs, and this late in the year I'll probably wait until spring before I spring.

So yeah, it's some bucks to get banged off, hopefully if more people make the plunge, the prices will drop so everybody can enjoy it.

Flying a nice, high performance electric job will sure spoil you. I guess it's up to each person to decide if that's how they want to spend their modeling dollars, but I'll tell you that my mind is pretty well made up.

I have two 5 pound profile electrics and I'm almost finished with my Extreme Flight 540. I was running 4120 AXIs BUT I have found a much better setup.
Now I'm running an AXI 4130/16. It spins a 17x10 prop and man is it sweet. Can you imagine all of that thrust over that much surface? I makes about 140 ounces of thrust. My problem was always batteries. Right now I have two 3s2p Thunder Power batteries, one in each wing. The are in series so it is a 6s2p. The max amp draw is 55 amps. The 4130 is good to 60 amps. I might be over taxing the battery but we will find out. Also I am never at full throttle.
I'm using a Jeti Advance 77 Opto speed controller. When you get big the Jeti Opto is really the way to go (not trying to push Jeti here, I have seen people try other things and have trouble).
Let me go find some photos and I'll post them.
The 540 will have the same setup. I have to figure out how to get the batteries in the wing but it looks like it won't be that hard. I have everything done except for mounting the rails to mount the AXI.