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.40 size profile electrics <nudgeing BH>

1829 Views 58 Replies 9 Participants Last post by  Jim T
Post what you ran into when electrifying your .40 size profile. Costs, issues with motors batterys etc. What equipment do you need an why.
Im interested in doing one but dont know squat about it. I know Billy does quite a bit of testing with this stuff.....has anyone else?
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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.

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Whoa I can see I need to bone up on my electrics. Not to mention that one battery packs gonna cost what $800?
around 15-25 bucks a cell. my tanic 3s2p cost like $160 I think? so you'd be looking at $300+ per pack for a 40 size ship, and so $600 in batteries lets you fly all day.

add to that a $100 motor, an $80 speed control, $180 of rx and servos and $150 in the plane, you've got some budget busting power!

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.
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I was having similar thoughts after running some figures that I had gotten that maybe a .25 size would be more economical then a .40. I dont really have any time on a .25 size plane though so dont really know much about there performance. But I can see that it would be a pretty good bang for the buck.
If my .25 size electric works like I think it will, I bet I'm gonna be in the same camp as Chuck....I'm gonna want a 40 size electric. Nothing beats going out to the field behind my house and draining 4 packs in my foamy. Being able to do that with a balsa .25 sized plane is gonna rock. I dream of taking an electric 40 size plane out to that field some day.
IM guessing over the next year or so Lipos are going to become a lot more reasonable in price as well as have a lot higher dishcharge rate. In the last year they went from what 4-5 C to upwards of 20 C today. On a side note I went and dl the video of Paulys Etaco TR and its seemed fairly stable. Or maybe he just flys that dang well.
You also need to look at Spastic's videos. His .25 sized planes are great.
yeah I've decided to do elecrtics up to 40 size and glow for 50 size and larger. of course, at the moment I'm actually at electric for up to 30 size and glow for 40 and above, but im working on it!

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.
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It sounds like the batteries are running your weight up a little bit? With that big of a prop you gotta have awsome controll for 3D. Bet that baby TRs like top too.
Actually, that's pretty good weight considering that motor alone weighs 14 1/2 oz. So 18 1/2 oz of batteries and you have 2 lbs of power system without an ESC or mount/prop adapter.

So coming in at 5 lbs is pretty dang respectable when you take that into consideration!
Oh I wasnt throwing off on his weight just that electrics bumped the weight up over glow.
That's not necessarily true. That particular electric bumps the weight up over glow, but there are other options that weigh less and will still swing a 17X10.

Billy is trying to come up with a nice plug-n-play system for guys to use on existing glow planes. If that system were to be used on a purpose built electric, the weight could be less than glow.

I'm building a 40 sized electric that will be just over 3 lbs with standard sized radio gear, it will be running a 17X10 as well.
Exactly Chuck. I'm looking for a setup that you could use when you gut your glow and go electric. When we start getting .40 size plane built for electric the power to weight ratio will be insane. This would also allow me to use smaller motors and smaller batteries. HEY! Maybe it's time for me to design a profile!
.....I gotta go to the workshop now.
I plan to have this one at Nashville.
Stay tuned for the next addition. :D
Some of you may recall I was testing the big Actro motor with the TP 10s4p pack which is actually two 5s4p packs. Anyway, last night the guy decided to call it quits on the electric heli project after smoking yet another ESC. ESCs and helis don't seem to get along well. Anyway, I am now the owner of those battery packs and I want to do a 40-60 size profile using one 5s4p at a time. I also have a brand new AXI 4130-20 but it won't turn enough RPM on the 5s to do much good and I don't want to cut up the packs. Would the 4130-16 do okay on the 5s packs? Is there a better choice that won't kill me financially? I have been looking at Dave's site,, and he is selling the Fiegao motors at fairly decent prices but don't know if anything there is suitable for my use. I am really wanting to e-power my next Burrito kit which I already have. Any suggestions???
It might work on the smaller 4130. I'm running 6s2p but I have INSANE power. I would try it.
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