I wanted to create a special thread where we put on our thinking hats and post things that apply in electric. I believe that if we want to go electric we need to build from the ground up with that in mind from get go. So let's see things that we can use to make a better electric bird  YaaaaYYYY      .

Fuselage building:
We do not need the thick doublers no more 1/16 ply can and should be substituted for 1/64 ply or even some 120g/M2 plain weave carbon fiber. We do not need anything that reduces vibration or design for high vibrations like the heavy duty engine crutch we used in IC motors. And yes there is no oil to worry about or increase in weight due to oil soaking through the balsa in time.
We do need to think battery position the balance the model longitudinal and lateral. We do need to think about cooling the electric components.

Wing and tails
Building wise it will all remain the same however the airfoils can get thinner and the wig tip thinner yet to get a better lift distribution and better performance for flying in the wind and reduced power consumption. Retracts are definitely an option. With active timers the motor run band can be anything we want it to be so there might be a good time to start some experimentation on new airfoils with better lift distribution that behave when you fly in the wind.  Yes we still need the lift to carve the corner but you can still get a lot of lift from a thinner airfoil too.

Power plant.
Yes we run electric motors now and unlike IC they develop max torque at low RPM opposite the IC counterparts. The motors can spin both ways and there is some exploration going in that direction with CCW props but since we are so used to the trim and yaw response feel of a CW prop and we are used to trim the models for CW props we tend to go to the Devil we know.
Light props are the way to go. I may add that single blade props are the most efficient power wise but since they are very much non-existing except for very special applications. 2 blade props should be the best for ow. You can make composite props that weigh similar to the 3B 12in hollow props in 2B 13-14in quite easy.
Igor will kick my ass on this one but here we go. I crunched some number in the prop thrust calculator and the most power efficient props for electric are high pitch and high diameter and the motors run low RPM (go figure they develop more torque at those rpm). I think we have to consider exploring this avenue.
Another detail that needs exploring is in the motor selection. As motors increase in size they work easier respond faster (especially if you go low rpm where they have more torque) but also their weigh increase. Now on the opposite side you use less electrons and batteries get lighter, and the ESC could get smaller and lighter but overall the weight of the system kind of remains the same (I call this the rob Peter to pay Paul kind of thing) . I crunched some #with a 4250 motor 13x8 prop on 4S at full rpm and a 5.5 min it was using 2100mAh at 21A that kind of started to open my eyes and question the status quo. 4S 2200-2500 are quite common and they are cheaper. Would you rather have odd low production run expensive batteries or go opposite.

Lets put the thinking hats on and find out what is worth wile.

Traian

Traian,

Smart idea! 

A guy like me could use complete "E" setups explained or listed based on model weight 'only.'

Would make things so much simpler and easier to digest.

Traian, good luck with this.

Charles

Simpler? Yes absolutely. Better? I highly question the result.
I can speculate how the current setups evolved. In the beginning there was person A who wanted to go electric, and he (most likely it was a he) most likely retrofitted his existing IC bird. Now he had to use existing space available to make this work. Most IC 60 size require a 35-36mm spacing between the motor mounts so here enter the AXI 28XX where the motor diameter is 35mm and it looks like it will fit so Yaaayyyyy i have a motor. Then he had a prop on the IC motor (3B 12x4) that will fit the electric motor so why not use that. The next problem was to spin said prop to kind of the same rpm it was spinning before (or maybe faster since it did not increase the rpm during flight like the IC does) now i need the big Amp ESC to make that happen and also need the volts and storage to go the distance, here enter the big 5-6S battery to make that happen. Tadaaaa I did it i am now flying electric. Everyone else is going well it works for him it must work for me too so let me copy it obviously it is the best that can be done since that is the best setup I can find. And the rest is history. Look at conversions in the RC world where a 46 setup is converted to electric and those G46 motors can handle a 13x8 14x10 prop sure you are jumping to put one on your model right? look at specs for the AXI 2826/13 it can spin a 16x8 (but that is on 3S) again more torque at low rpm. 6500rpm with 16x8 I am sure is more than enough to move our birds in the air and it produces 142oz of thrust.
We found out that light props use less energy and less gyro procession so we have gone in that direction which is the only step forward we have done so far.
The thing is that you can always fall back on the things you know but there is nothing wrong with asking questions and try new things that are easily changed if they do not work. And I for one am certain we far from optimum and this is the purpose for this post to start thinking electric, understand electric and perhaps come with ideas to push it to next level.

Igor will kick my ass on this one but here we go.

 

Well usually I write one thing only once, too many open projects to spend time explaining the same thing many times :- )))

And, if I'm not mistaken, perfectly balanced at only one RPM, airspeed, and airplane pitch (or, perhaps, some reduced-dimension surface within some larger dimensional space that probably includes the density altitude and very probably the phase of the moon).  Even the speed and gas FF guys don't use 'em any more.

From what I have seen F2A models all still run single blade props. Other events have eliminated them by rules.

For F2B the three blade prop is less efficient than the 2 blade, but it is more effective.  (Runs smoother in the corners for example)
You just need to up the battery energy to compensate.
I went from 12x6 APC on 4S 2700  to Igor's 3 blade 11x5 on 5S 2700.
mAhr consumed is about the same with both setups, thus about 25% more energy used for the three blade.

I think it is safe to say we have the big planes pretty much set, however the small .15 size is another matter.
The approach to the smaller planes so far for CL has been not so good. We keep trying to use way bigger batteries and motors and expecting the planes to fly decent with the same approach as we do on the bigger planes. It's not working.  So I myself have been looking at the current way we are sizing things and looking at what the RC side is doing. Simply equating IC to electric and vise versa only gets you so far. A new approach to this is is always a good thing, it verifies what we are currently doing and can expose some holes in other aspects. It's good to discuss things like this.

I would love to see this.  I am getting back in after 30 years and I have seen an electric fly which blew away all of my concerns.  I build and design my own so I would love the forum.  I read as much as I can on the engines and it is pretty clear that they have been around long enough that the people writing about them  assume we all know what they are talking about.  Just simple stuff like I fly a .46 size plane.  A Shark 45 would be a good sample.  How big an electric do I need?  Would the same engine power a something smaller, like the size of a Nobler, if I ran it slower?  Can I run it slower?  Can I still do a cloverleaf with the extra 2oz of nose weight (si)?  It is like waking up after a 30 year nap!

I would love to see this.  I am getting back in after 30 years and I have seen an electric fly which blew away all of my concerns.  I build and design my own so I would love the forum.  I read as much as I can on the engines and it is pretty clear that they have been around long enough that the people writing about them  assume we all know what they are talking about.  Just simple stuff like I fly a .46 size plane.  A Shark 45 would be a good sample.  How big an electric do I need?  Would the same engine power a something smaller, like the size of a Nobler, if I ran it slower?  Can I run it slower?  Can I still do a cloverleaf with the extra 2oz of nose weight (si)?  It is like waking up after a 30 year nap!

The method I used when I got started in electric was to look at the prop chart for electric motors.  I knew the prop size and RPM range for a given size gas engine.  Looking at electric prop charts I looked for motors that would swing a similar size prop at a comparable RPMs.  However the RPMs need to be some what higher to allow room for the RPM governor to work.  Cobra motors have good prop charts.  According to the prop chart a Cobra C-2826/10 will turn a 11x5.5 prop at 10372 RPM.     http://innov8tivedesigns.com/parts/brushless-motors/cobra-c-2826-10-brushless-motor-kv-930      I am turning this prop at around 8900 RPM.  So this is probably around a 40 to 46 size engine.  A bit of a crude approach but it is how I started.   As with any new approach the key to success is to  read, read, and read some more.  Also look for folks close by that are flying electric for advise.  Another good starting point is to buy a ready to install electric motor package from RSM.  It includes a matched motor, speed controller, timer and battery with all of the connectors installed.  They are listed by gas motor size equivalent.   http://www.rsmdistribution.com/index-2.htm

I often learn a lot when someone brings up an old thread that I missed before.

Mark