Ep 69: Best of Episode: Electric Motors, ESCs

[00:00:00] Hi guys. While Ron and Tom are taking a well-deserved break, we hope you enjoy this best of episode of RC Plane Lab. And remember, they'll be back with new episodes starting June 11th. We hope you enjoy. For anyone interested in RC Airplane, we'll share tips and tricks on how to build models and talk about successful flights, epic crashes, and everything in between. Visit us at rcplanelab.com to sign up for our email list and to ask us questions.

[00:00:36] You can also text us or leave us a voicemail at 818-351-9846. Please help us out by rating and reviewing us in your favorite podcast app. Thanks for spending time with us today. Now here are your hosts, Ron and Tom.

[00:00:50] Hello everyone and welcome to the RC Plane Lab podcast. I'm Ron. And I'm Tom. On tonight's episode, we are finally going to be tackling electric motors. Oh boy. So this is going to be a fun one. There's going to be a lot of information that we go over. Yep. So let's get started. Are you ready?

[00:01:10] Before you get started, can I just say one thing?

[00:01:12] No.

[00:01:13] So in the last episode, I was talking about Ringmaster Jr. RMJ Machine Works.

[00:01:18] Yeah.

[00:01:19] I did make a small mistake.

[00:01:21] Oh, come on.

[00:01:22] I know, I know. It's hard to believe, but I do make them occasionally.

[00:01:27] Actually, I make them a lot. Just ask Lori. Yeah, or me.

[00:01:30] Yeah. Well, anyway, I mistakenly called his piston rings steel. And while technically they

[00:01:37] Are derived from iron ore, his rings are actually iron rings. They're not an alloyed steel of

[00:01:45] Any kind. So I just wanted to clarify that. I made a mistake and just wanted to make sure that I didn't lead anybody down the wrong path about what his rings are made of. They're made of cast iron, or they're made of iron. And they're very, very good quality. I did say

[00:02:00] That. And they are. I stand by that. They're really good quality. So sorry about that, Bjorn.

[00:02:05] I did get that wrong. Hopefully I got it correct now.

[00:02:09] This is actually an odd episode for us because it has been, well, months, I guess I would say, since we actually sat down in person to record.

[00:02:18] Yeah, and this is kind of weird.

[00:02:20] And your ugly mug is right in front of me now.

[00:02:22] To be honest, this is really kind of, yeah, freaking me out a little bit.

[00:02:24] I know. It's just an odd, odd way of doing it.

[00:02:27] I think I'm going to have to go in another part of the basement to do this. I don't think we can do this like that.

[00:02:31] You just want to go sit in your car and call in? Exactly. Anyway, electric motors. Are you ready to start on this one?

[00:02:39] Well, I'm ready because I really didn't have to do much of the work. You did all the work for this episode, and I appreciate that. But yeah, I'm ready.

[00:02:49] Okay. Well, here we go. Here we go. So first off, let's talk about some definitions before we get into what actual electric motors are.

[00:02:59] I think that's a good idea.

[00:03:00] So electric motors, you're going to hear a lot about volts. You're going to hear a lot about amps. You're going to hear a lot about watts and resistance. Let's start by, I kind of want to try to explain some of these concepts. I think having a basic understanding of all this kind of makes it easier to understand how our RC airplane electrical systems work. So it's a lot easier for me to grasp these concepts when I relate it to like a garden hose.

[00:03:30] Yep. I've heard that analogy before.

[00:03:34] Well, you're going to hear it again.

[00:03:35] That's awesome. That's a good one.

[00:03:37] And if I get anything wrong, hey, chime in.

[00:03:40] Yeah. You're on your own, buddy.

[00:03:43] Okay. So let's make some comparisons. Stick with me. And I hope that I explain this well enough that it all makes sense. Okay. So volts are supplied by our battery. Volts are what does the pushing of the electricity. So think of volts as the pressure you have from your spigot before the valve is turned on. So if we're comparing this to a garden hose, okay? Yep.

[00:04:08] So that's the stored energy you have access to. An amp is a measurement of current. So that would be analogous to the water flow through the garden hose. So the higher your amps, the bigger your garden hose. Right.

[00:04:24] Resistance is going to be anything that slows down the water flow. So the spigot valve, the hose nozzle, even the size of the garden hose, both diameter and length will cause resistance. Yep. So, and resistance is measured in ohms for electricity. Yep. So you'll also hear about a voltage drop across wire. I saw, actually it was kind of funny because I saw a prime example of, of water hose voltage drop, if you, if you will, that, that was in air quotes,

[00:04:55] By the way. Got it. So, but I saw a couple of days ago when my wife was watering her garden, she just bought three of those, 50 foot sections of the, the surgical tubing garden hose stuff, like the, the expandable kind. Oh, right. Yep.

[00:05:08] So she turned the hose on and they all expanded to their full length. She walked out to the garden with the nozzle. The whole, or the, the hose was full of water, and at full pressure. So as soon as she pulled the trigger on the hose nozzle, the hose started to shrink and get shorter and the pressure coming out of the end of the hose was lower.

[00:05:26] It wasn't a huge difference, but it was noticeable. So, so the voltage or the pressure of the water dropped because of the resistance of the garden hose. Because of its length. Because of the, the length, correct.

[00:05:37] Right. Okay. So, so yeah, the longer the hose or the longer the wire, the higher the voltage drop is going to be. If she was watering with a 25 foot hose, the water flow at the end of the nozzle would be much greater than if she used her 150 foot hose. And if she connected more together to make it longer, the flow at the nozzle would be much less still. Electrical power is the product of the voltage in the current, which is measured in Watts. Think of the Watts as the amount of water that comes out of the end of our garden hose to, to water your plants. But the water is just

[00:06:09] Measured in gallons instead of Watts. Okay. So, we'll, we'll kind of talk more about this later when we discuss picking the correct size motor, ESC and battery, but I wanted to make sure we kind of touched on it before we get going. So hopefully by the end of this episode, that will all make sense. If not, we'll all be confused, whatever.

[00:06:26] Well, and then we can expect a lot of emails with questions, right?

[00:06:29] Yeah.

[00:06:30] And messages.

[00:06:30] That's true. so stator and rotor. That's the next thing I kind of want to bring up.

[00:06:38] Okay. now you're referring to the motor itself.

[00:06:42] Correct. Yeah. Thank you. So the stator and rotor are what hold the magnets in a motor. So the stator is a stationary part of the motor and the rotor is the part that spins either in the stator for in runners or around the stator for out runners. it's actually easy to remember once what each one does, rotors rotate, stators are stationary. Well, that makes sense.

[00:07:06] The stator is the part of the motor that has a wire wrapped around the magnets that create the electromagnetic field that spins the motor. think of it this way, the, the wires that plug into your speed controller that are, that are going to the stationary part of the motor or the stator and the, the propeller is connected to the rotating part of the motor, which is the rotor. So, next thing before we move too far in runner and out runner. Types of motors. Types of motors. Yeah. Electric motors. Types of electric motors.

[00:07:38] Since that's what we're talking about. Since that's the topic. okay. So on an in runner motor, the rotor or remember the rotating part of the motor, is on the inside. So you will normally only see the inner shaft spin when you spin an in runner motor. in runners can normally spin much faster than out runners and are mostly seen like in, in smaller aircraft.

[00:08:01] Just because they, they don't really make as much power as like, an out runner does. But anyway, so these can be mounted from the front of the motor since, the only part of the motor that spins is the shaft. Out runner motors, which are more common and bigger RC aircraft. the center of the motor is stationary for an out runner and the outside can, or the actual outside part of the motor rotates around the stator.

[00:08:28] These are generally lower like, revving motors. So they, they usually run a, like a lower RPM, but they do produce more torque, which makes them great for spinning a propeller on an airplane. So, well, let's talk a little bit more in depth about some motors. So in our hobby, we will come across two different types of motors, brushed and brushless.

[00:08:54] So first off brush motors. So I was talking to my wife last night about this and, we, as we kind of got talking about brushed and brushless motor, she said,

[00:09:04] Which by the way, how cool is that, that you're able to talk to your wife about this hobby?

[00:09:08] Oh, she, she listens to a lot and puts up with a lot.

[00:09:11] Well, sorry to interrupt you, but that's really cool that Crystal listens to you.

[00:09:17] But what I, what I think is funny is, is she thought, and she, she, she doesn't deal with this stuff. So I'm not trying to put her down or anything, but she thought the brushes were actually like bristly things, which you can, you can kind of understand that. Yeah. I could see that picture. Because brushes, you think of like a hairbrush or something like that.

[00:09:34] So these motors don't have little bristly brushes on the inside, like, like we talked about last night with her. The brush is just a contact that is made of carbon. Basically, like, as the name suggests, brushed motors have brushes and brushless motors don't. And so I remember when I was starting out in RC, it was not, airplanes, it was cars back at that time, but everything was brushed. This has been, oh gosh, 15 years ago, even maybe even 20.

[00:10:03] Right.

[00:10:04] And I used to go through brush motors a lot on my, on my, on my RC truck. And I remember, I think it was somebody at the hobby shop, but I, I don't remember exactly where it was that I heard it. But they told me to break in a new brushed motor by running it underwater, like submerged completely underwater. Apparently it like, I think they told me it like helped, like the brushes wear into the commutator and it made the motors run longer before it was break.

[00:10:29] Is that, was I okay doing something like that?

[00:10:32] Yeah. Yeah. That's absolutely a thing. back when I was in, into cars and stuff too, new brushless motors, or I'm sorry, excuse me, new brushed motors, specifically Mubuchis, which are the sealed can, which you, you couldn't rebuild them. over time evolution with the electric motor, we could rebuild our brushed motors. we could take them apart and, turn the commutators on a lathe and things like that.

[00:10:56] But anyway, on those sealed can motors that you couldn't do any of that, the, the way you would develop power out of them was to maximize that surface area friction of those brushes on the commutator or the armature. The commutator is part of the armature, which you're going to talk about in a minute.

[00:11:11] Yep.

[00:11:11] But the way to do that was to break them in. and if you were breaking them in, in the car, there was no way to really control the load or the, the temperature. They would get hot and they would arc and they would, do all these nasty things, which would make them inefficient or make them tend to be inefficient and not develop their maximum power.

[00:11:31] So we would break them in, we would just take them and run them at a low voltage and we would usually run them. these are 12 volt motors, right back in the car days, we would run them at five volts and just simply take the, take the motor by the leads and dunk it in a cup of water. And let it run for, five, 10 minutes, whatever it took. And the water would get all dirty. And that's when we knew it was working, doing its magic.

[00:11:54] But basically what it was doing was putting a load, a light load on the motor at a low voltage and it would just run those brushes in on the commutator. And that water would kind of act as a coolant to keep it from overheating and arcing and things like that. So it would make, it would maximize that, that surface contact and make the motors develop their maximum power.

[00:12:14] So is that kind of like wet sanding then?

[00:12:16] Kind of.

[00:12:16] Kind of like that same.

[00:12:18] If you want to think of, because there's that physical contact of the brush.

[00:12:21] Right.

[00:12:21] On the commutator. So in that water in between, yeah, it could be thought of as a very, very, very, very fine polish if you want to consider it that way. So yeah, wet sanding, the comm, if you want to look at it that way. Sure.

[00:12:33] Yeah. I mean, it's just counterintuitive running an electrical motor underwater. I know. Yeah. Yeah. Because we all know water and electricity don't mix. So when I, I did do that, I used to do it with some of mine and.

[00:12:45] Yeah. We did it all the time back in the car days.

[00:12:47] Yeah. And it worked.

[00:12:48] No, no. You were, you were, you were right on track.

[00:12:50] All right. So back to it. Brush motors. Brush motors only have a few parts. And I kind of want to talk about what each one does. So they consist of stator magnets, which are the stationary and permanent magnets. And these are the ones mounted inside of the shell of the motor, the armature, which is also known as the windings, and then a commutator. And as the name suggests, a set of brushes. So brush motors have two external wires that you connect to your power source.

[00:13:18] As these wires are electrified with DC current, the electricity runs through the brushes and goes to the commutator. I, I always had a problem remembering what the, the commutator did, but one day it hit me that the commutator communicates the electricity from the brushes to the winding. Once I kind of thought about it that way, it helped me a lot. but the commutator is a little electrical pad inside the motor and it's connected to the windings.

[00:13:44] And the windings create an electromagnetic field. So this field is what interacts with the stator magnets in the motor shell. And that's what causes the rotation of the motor. So as the motor spins, the brushes make contact. They physically make contact with the different parts of the commutator. And that reverses the polarity on the windings and pulls the motor farther through its rotation. this continues on and on. And that's what makes these little motors rotate.

[00:14:10] The problem with brush motors is that they are not nearly as efficient as brushless and they don't last nearly as long. and really that's just because of the physical interaction of the brushes riding on the commutator. so therefore like brushes are a wear item and the, the commutator can also go bad.

[00:14:30] So that's kind of about as deep as I want to go into how brush motors work because, for the most part, many of the, the electric airplanes we deal with today are brushless. so I think we'll spend most of the time talking about brushless motors. Yep. so the last thing I want to say, so if you see like a motor sitting around and you're, you're not sure if it's brushed or brushless, the easiest way to tell is by how many wires are coming out of it.

[00:14:55] So brushed RC motors have two wires and brushless RC motors have three wires. Anything you want to add to brushed since?

[00:15:02] No, no, I mean, I think that, I think you're right. I don't think there's much point in going too deep into brushed motors because not that they're obsolete, they're just not as common as they used to be. And what is common is brushless motors.

[00:15:17] Yeah, definitely not for what we fly and how we fly. So, they still have their place for other things, but not really what, what we do. So brushless motors, this is going to be the, the motors that we are all familiar with. So these motors are different from brush motors, obviously, both in the way they're constructed and the way they work. So a brushless outrunner, is going to be the most common type of motor we see in the hobby.

[00:15:45] So let's, let's talk about that for a minute.

[00:15:46] All right, let's do that.

[00:15:47] The reason brushless motors run without the use of a brush is because the armature is no longer the spinning part of the motor. And because of that, there's no need to electrify a piece of the motor that is moving. So we'll, we'll, we'll talk a little bit later about ESCs, but the, the reason these motors can operate, is because the electronics progressed to the point where they were smarter. Well, I guess not necessarily smarter, but they were, more advanced.

[00:16:13] And they became, kind of in a loose sense, a computerized brush. let me kind of explain that and see if that makes any sense. So in a brushed motor, the armature had to be the part that was electrified because there was no other way to reverse the polarity of the electromagnetic field to keep the motor spinning.

[00:16:32] If you were unable to switch the polarity, then the motor would just move to the, the position that the magnets were attracted to and not continue on with its rotation. so since the armature and commutator spun, the electricity delivered to it by the brushes was able to reverse the polarity and continue to spin the motor. So brushless motors don't have that issue because the electromagnetic field is controlled by the ESC.

[00:16:57] And since the, and since the electromagnets are on the stator and the permanent magnets are on the rotor, there's no need to transfer any electricity to a moving part. therefore the biggest limitation to brushed motors were eliminated.

[00:17:12] Mm-hmm.

[00:17:13] So no more brushes, no more commutator, no more friction between the brushes and the commutator to slow the motor down.

[00:17:20] Yep.

[00:17:21] No more sparks to follow up the connection between the brushes and the commutator. Yep. No wear items. Yeah. So, a brushless motor is really a simplified brush motor, almost an inside out brush motor, or at least flipped, I guess, not quite inside out.

[00:17:36] That's how I used to, that's how I used to, like when brushless motors first came on the scene with, with RC cars back in the day, that's how, in my head, that's how I made sense of how they worked is like, just take a brush motor, flip it inside out and control the magnetic field electronically instead of mechanically. And there you had it, that was a brushless motor.

[00:17:56] Yeah. Yeah. They really last a lot longer. Oh my gosh, yes, they do. So, and, and the reason for that is because, the only wear items that are in brushless motors now are the bearings on the front and rear of the motor. I guess some have more than two bearings, but it's, do the bearings is the only thing that can go out. Yeah, that's the only wear item.

[00:18:14] And, they come in a lot of different sizes and they each have their own little specs that are good to know about.

[00:18:22] So this is the fun part. This is the part I hate.

[00:18:24] I mean.

[00:18:25] It's not that bad.

[00:18:26] No, it's not because, I know how you're going to break it down. we've talked a little bit about it, which has helped me a lot, but it's so intimidating. There's so many numbers on the cans and each manufacturer, they don't list it the same. And it's not as simple as picking a glow powered motor.

[00:18:43] No, it definitely is not. those glow motors are very simple on this is the size you need. This is power you're going to get out. And that's what you put on it.

[00:18:53] Electric motors are a whole different beast. Yeah. And, there's a lot to understand about them. So let's, let's take a motor I bought not that long ago and kind of use it as an example.

[00:19:05] Okay.

[00:19:05] So, the numbers on the motor are A, 2212, 1400 KV. So let's break that down. Okay. The A. So the letters don't really denote anything specific about the motor setup. Great. Ignore them. Pretty much just ignore them. they usually are like a manufacturer's brand number or series number of the motor. Oh, okay. sometimes depending on the manufacturer, they'll be labeled like with an S for a short can or like an L for a long.

[00:19:35] But, on the whole, nothing really to concern yourself with. I did not know that. Yeah. So ignore it.

[00:19:42] Okay. Well, easy enough.

[00:19:44] So the 2212, this, this gets a little tricky since there's not a standard, like naming convention on these motors. Right. so it's a, this four digit number is really a set of numbers that gets broken down into two separate sets of two numbers. Okay. The first two numbers, the 22, tells us either the exterior motor diameter or the rotor diameter. So depending on what brand you have. Right. Right.

[00:20:16] They will either be measuring the actual outside diameter of the can. Okay. Or just the diameter of the rotor magnets.. That's not confusing at all. No, it's not. And, and the, the next part is the same. So the second two numbers, the 12, either tells us the height of the motor or the height of the rotor.

[00:20:38] Since there's really no standard in these motors, the only real way to know what the numbers refer to, are going to be by looking at the spec sheet, or the, like the description of the motor. So the spec sheet.

[00:20:50] And some manufacturers are better at putting that information out there than others.

[00:20:54] Yeah. It's very difficult to find it for some motors. I've, I found that out the hard way. Yeah. but this one did come with a spec sheet. Cool. and it tells me that the, it's a 28 millimeter can. So that means the outside diameter is 28 millimeters. So now that I know that, that means the numbers that are written on the outside of the motor are talking about the rotor diameter. Mm-hmm. Since the first two numbers are 22. Right. Not the motor measurement itself.

[00:21:20] Right.

[00:21:21] If it was talking about the motor, it would start with 28 instead of 22. That's really the only way to tell.

[00:21:26] Okay.

[00:21:27] .

[00:21:28] Well, that's easy enough. I mean, that's just looking at the spec sheet.

[00:21:30] It is. If there's one. If there is one provided. Correct. so the 1400 KV.

[00:21:36] There we go. KV tells us. Now, this one is fairly standardized, right? Yes. Like most, every motor that I've looked at has a KV number. And if it says KV, that's going to be pretty much standard lingo, if you will, when it comes to these motors, right?

[00:21:52] That is correct. Okay. But that doesn't tell you anything about size or power.

[00:21:57] Okay.

[00:21:57] So, but you are correct. And the KV rating is a standardized measurement.

[00:22:03] My brain, my brain works with standards. So, I like it when something is standardized. So, then I can, it makes it easy to compare. what I mean?

[00:22:11] Yeah. It makes it a lot easier to figure things out. So, the KV of motor, the KV of a motor tells us under no load how many times the motor will spin in one minute with one volt applied. Oh. So, at one volt, it's the RPM rating of the motor. So, our motor here will rotate 1,400 times in one minute with one volt applied. So, the specs for this motor say it's designed to be ran with a 2S or 3S LiPo. So, if we do the math, a 2S LiPo is 7.4 volts.

[00:22:42] This motor will spin at 10,360 RPMs on a 2S battery. With no load. With no load. And at 5, or at, sorry, at 15,540 RPM on a 3S 11.1 volt battery. Now, like I said, yeah, you're right. Remember, those numbers are all no load numbers. So, you won't really get that RPM, but it's going to be close enough kind of for our purpose here.

[00:23:03] Okay.

[00:23:05] The spec sheet for this one also tells us some other important information. So, max efficiency is 80%. The higher efficiency, the more efficient the motor is at spinning a propeller, which means less wasted energy. And the lower efficiency a motor is, the more heat it produces since the heat, is the byproduct of an inefficient electrical system. Right.

[00:23:27] So, the more efficient you have, the more flight time you're going to get out of it, the more kind of bang for your buck, I guess, you're going to get with your battery sizing and stuff. So, the max efficiency current on this one is between 4 and 10 amps. And it says that in that range, between 4 and 10 amps, it's over 75%. So, it doesn't tell us where 80% comes in, but it's going to be somewhere in that 4 to 10 amp range.

[00:23:54] Would that be kind of like looking at, say, putting a car on a dyno and running a car on a dyno and seeing its peak horsepower and peak torque curves? Is that, when you're looking at max efficiency at, between this range, so between 4 and 10 amps, it's 75% efficient in that range with its peak somewhere probably in that range, right?

[00:24:16] And so, it's going to be over 75% efficient. I'm sorry, over. Throughout that range, but yeah, we don't know what that curve looks like. So, somewhere in there, if they're saying it's an 80% efficient motor, somewhere between 4 and 10 amps, it's going to hit 80%. Got it. But between that whole 4 and 10 amps, it's not going to be under 75%.

[00:24:34] Got it.

[00:24:34] So, that's how they kind of figure that one. And then it says current capacity is going to be 12 amps for 60 seconds. So, it's going to be able to handle 12 amp bursts for one minute.

[00:24:47] Pretty simple. Pretty straightforward, yeah.

[00:24:49] So, it tells us the no-load current is 10 volts, or I'm sorry, tells us the no-load current at 10 volts is half an amp. So, when it's just sitting there idle at 10 volts, it's going to use half an amp of current. And it lists the number of cells, like I said before, as two to three cells lipo. And it gives the motor dimensions of 28 millimeters by 30 millimeters. And then it tells us that the shaft diameter is 3.17 millimeters. And then it tells us the weight is 47 grams.

[00:25:21] That's all stuff that when you're trying to set up an airplane, you need to know. Weight, because you're going to want to try and balance your plane. So, you're going to need to know if you're having a, you're putting a heavy motor on the front or if it's going to be a light motor. Shaft diameter is important, so what kind of- Prop adapter to use. Prop adapter to get, right.

[00:25:40] So, there's, most of these are going to be either like 5 millimeter or 3.17 millimeter. I don't think there's a lot of other sizes on these smaller motors. And then when you get into like the bigger, bigger motors, the prop adapters will actually screw on the front of it. So, it's not going to be- So, it's a threaded shaft then, more or less. Yeah, it'll have screws that go on to the front and then you're going to put it on. Kind of like a great shaft.

[00:26:02] Yeah, and then you'll put it on, you'll put your propeller on just like you would like a nitro engine or a gas engine. Right. So, okay, another one I have. Let's go over it really quick because it's a little bit different. Okay. So, it's labeled CF2822 slash 14, 1200 kV. There's a little difference between it and that last one, so that's why I want to talk about it. There's an extra number in there. Yeah, there is. So, let's go through it really quick.

[00:26:30] CF doesn't really tell us much of anything. I can ignore that. Yeah, ignore that. 2822 tells us the motor or rotor diameter is 28 millimeters. And the 22 tells us, once again, the height of the motor or the rotor. So, I don't have a spec sheet for that one. That was just one that I had on another airplane that was down here.

[00:26:47] So, since we don't have it in front of us, we can measure the can or the outside of the diameter of the motor to find out what the numbers are referring to. Okay. So, it measures 28.54 millimeters. So, on this one, the numbers are talking about the can size or the actual measurements of the diameter of the motor. The next two numbers were not on the first motor we talked about. So, the slash 14 refers to the number of turns in the motor. Oh.

[00:27:13] The higher the turn number, the lower the kV of the motor.

[00:27:17] Like when you say, oh, okay.

[00:27:20] Yeah, so, the turns refer to the number of times the copper wire has physically been wrapped around the stator of the motor. So, like I said, higher turn motors have lower kVs, but they do have more torque.

[00:27:33] So, if I could interject. Sure. Same principle for the old brush motors. Remember that? the higher turn motors was the same thing. They were lower RPM, and they developed a little more torque, and the smaller wound motors were the opposite.

[00:27:49] Yeah, because remember, these motors are pretty much the same.

[00:27:52] Inside out brushed motors.

[00:27:54] Well, yeah, but they're still going to be doing the same thing. Right. They're still going to be made pretty much the same way, but there's a little bit of difference in how they're controlled. Yep. Really. Got it. That's the biggest thing. Yeah, okay. So, like I said, the higher turn motors have more torque, and so, because of that, they're able to spin larger props.

[00:28:15] Also, as the physical motor size increases, most of the time, the kV of a motor decreases because of the way it's constructed. That's okay, though, because the bigger, lower kV motors run on higher voltage. So, even though the kV is lower, the overall performance increases. Cool. It would be very nice if, like, labels would be standardized. I really don't know why they aren't. Yeah, why aren't they? Man. Just to make it harder on us.

[00:28:43] Motor manufacturers, if there's anybody involved with the manufacturer of motors, and, like, anybody who's, like, part of a board who, like, comes up with the, naming, standardize it, please. It would make it so much easier for us.

[00:28:58] Well, and they, there are companies that have tried to make it a little bit better. So, like, if you look on some of these other websites, they will call them, like, 46 size motors.

[00:29:10] Thank you, E-Flight.

[00:29:11] Right. But, and I guess that's good if you don't need to know the exact. If you're just wanting to buy straight off the shelf, this is the motor I need, this is the speed controller I need, you told me this is what I need for this airplane, that's perfect. I mean, that really is a good way to do it. But if you kind of want to understand it more, then it would be nice to have those numbers because they're not listed online that I could find.

[00:29:34] Or if you're, kind of designing your own airplane or you're building your own airplane to your own specs, you'd like to know those numbers so that you could match it to, your particular airplane.

[00:29:44] Yeah, that's true. Last thing I wanted to say on brushless motors really quick. So, when you're working on them, and you're getting it set up, if you have to reverse the rotation of a brushless motor, just swap any two of the three wires going to the motor from the speed controller. So, if you hook the motor up and it spins backwards the first time you powered out or powered up, don't worry about it. Just switch the wires and you're good.

[00:30:12] So, it's a good thing to remember. It is. So, now that we know a little bit about our brushless motors, we need something to make them spin. Yep. So, the brushless electronic speed controllers or the ESCs that we all know and love take the direct current or the DC from the battery and it converts it to a three-phase alternating current or AC. And that is what the motor needs to spin. So, the terms ESC, speed controller, electronic speed controller, they're all interchangeable.

[00:30:45] If you hear somebody say that, say any of those things, they're all talking about the same thing.

[00:30:49] So, unless they say speedo, sometimes that's not the same thing. I'm just saying.

[00:30:56] What?

[00:30:57] In the car days, we used to call them speedos.

[00:31:00] Why?

[00:31:01] Just because it was short for speed control or electronic speed control. So, we just said, hey, I'm running a Novak speedo or whatever. Yeah. Well, that's weird. Speedo doesn't mean the same thing to the same, to everybody. Just so.

[00:31:15] Well, to me, that's short for like speedometer even. So, I don't know where you get speed control or dynamic if you want to go there. I don't want to go there.

[00:31:24] Sorry. But anyway.

[00:31:26] Oh, boy. Yeah.

[00:31:28] So, those terms are all interchangeable.

[00:31:30] Yeah. Let's get back to that. So, ESCs interpret the PWM signals or the pulse width modulation signals that come from the receiver. So, we may get into it like a deeper dive on how electronics or your radio system work. how servos work and how some of the other more technical stuff works in another episode. Maybe. Maybe. I don't know. We'll see. We'll see. But for now, just know that the width of the signal pulse determines how fast the ESC spins the motor.

[00:32:03] Kind of the same with servos and all that. But like I said, we'll not touch on that now. So, the ESC sends the electricity to the motors at different frequencies based on what speed the motor needs to spin. And that is based on the signal from the receiver. So, the motors are in sync with the frequency being produced by the speed controller, which is why the motors are called synchronous motors, if that makes any sense. So, it's all synchronized to the frequency.

[00:32:31] I've never heard them called that, but it makes sense.

[00:32:34] There's synchronous motors. There's asynchronous motors. Mostly, like, asynchronous motors are usually like the DC motors that kind of are not directly correlated, like, spinning with a frequency. So, if that makes any sense, it doesn't matter. Let's move on. So, the speed controllers we're talking about, they're like tiny little VFDs or variable frequency drives. And if you're not familiar with VFDs or you've never heard of them, that's okay.

[00:33:03] Because you don't need to be familiar with it for our purposes here talking about RSC airplanes. But the reason I want to bring it up is because of my CNC machine. So, I know there are some people listening that have it in the back of their minds that they want to build one CNC machine. At some point. If you don't want to build a CNC machine, cover yours for the next few seconds because I'm going to talk about it. Done.

[00:33:25] I remember when I was doing all the research for the CNC router, trying to figure out what spindle and VFD to get. And it was really overwhelming and really confusing. So, to bring that back around to RCA airplane ESCs, my CNC setup is really like an RCA airplane, just quite a bit bigger. So, here's how. The VFD on my CNC router converts the 220-volt house electricity to three-phase AC that the brushless spindle needs.

[00:33:54] And the spindle is a 2.2-kilowatt water-cooled version of an RCA airplane motor. So, the VFD gets signal from the computer to tell its speed, just like the receiver talking to the ESC in the airplane. So, in case anyone was thinking about building a CNC machine and putting the spindle on it instead of just a plain old router, hopefully that's a little help in figuring out the whole system.

[00:34:13] So, once I realized they were basically the same electronics, figuring out the CNC stuff became a lot easier. So, if you're wanting to build a CNC machine, don't be scared away from it like I almost was because of its complexity. Okay. I'm finished with CNC talk. Okay. So, you ear covers, uncover your ears now. Come back to us. So, speed controllers are pretty complicated little electronics. Yep. But we really don't need to concern ourselves with how they work exactly.

[00:34:39] For these things, we just need to know what to look for when deciding on which one we need. Most speed controllers have a few settings that can be programmed based on your application. And the programming instructions will either come in the package with the ESC when you buy it, or it's going to be available on the website where it came from. So, each ESC's programming sequence is going to be different. Lovely. Yeah.

[00:35:01] More standardization.

[00:35:03] Some are programmable from the transmitter. Some have a little card that plugs into it to program it. Some actually connect to a computer for programming. And there are actually some that aren't programmable at all. The way you get it is what you use it for. So far, I haven't had one that uses a computer, but I have used a transmitter for some and the card for some.

[00:35:27] Sometimes there's nothing that you really want to change or need to change, so programming isn't necessary and it'll work just fine, like for what you're doing straight out of the package. You'll have to refer to your manual or look at the manual online for specific directions for a particular ESC. And what I actually find funny, so, Tom came out a little bit earlier before we started recording this and he has a little airplane that he got.

[00:35:54] I don't know where it came from, but he had never flown it before and it's just a little foam edge, something fun just to fly around the yard. So, he's got to learn how to program his ESC because when he turns it on, it plays, oh, Susanna.

[00:36:13] Yeah, I've never seen anything like that.

[00:36:16] Yeah.

[00:36:16] As soon as you plug the battery in and it arms everything, it plays, yeah, oh, Susanna.

[00:36:23] It's actually not as uncommon as you would think.

[00:36:26] Yeah, because I've never heard that before.

[00:36:28] So, the little speed controllers that I just bought, we talked about that engine or that little motor that I bought earlier. The speed controller directions that came with that, I was reading over those before I put it all together in the airplane. And you can pick from like seven different songs that it will play when you turn it on.

[00:36:44] How do you make it not play a song?

[00:36:46] That's what I'm interested in knowing. Oh, you can't. Yours is going to do it forever.

[00:36:52] It probably will because there's no label on it, so I have no idea what brand it is. Because I have no idea how to program it. I have no idea. All I know is that I plug the battery in and it just works. It's like black magic or something. I don't know.

[00:37:08] Well.

[00:37:09] I'm sure there's probably a way to program it, but.

[00:37:12] Well, and okay, so it kind of is a little bit cool, the fact that you can play a song with it. Because what it's doing is it's using the motor. Right. the frequency of the motor. Yeah. And it's making it rotate and it works.

[00:37:25] Well, and that's what sound is, right?

[00:37:26] Right. Frequencies. But just to be able to do it straight from that, it's kind of a cool feature to be able to do in.

[00:37:35] Yeah, but oh, Susanna.

[00:37:37] It's a cool feature to have in theory, but in practice, cool once or twice, but then I think it gets old.

[00:37:44] It gets old because it does it every single time I plug a battery into this thing.

[00:37:49] Oh, okay, so let's get back to ESCs. So it's important to know the current, both continuous and the peak ratings for your ESC. You're also going to need to know what battery it's designed to take. You're going to need to know if it has a BEC or a battery elimination circuit. And if it does, you're going to know the rating for the BEC for voltage and current.

[00:38:14] The BEC is designed to eliminate the flight battery that we use in our nitro airplanes and the ones that we use to power the radio equipment and the servos. So when you look at the spec sheet or the label, if it has one, it will tell you the amps and voltage the BEC provides. So in a typical wiring setup for small electric airplanes, your battery will plug directly into the ESC and the motor also connects to it. Some ESCs have a short lead with a power switch turned on or off.

[00:38:44] Not all of them do, but some do. And that switch is supposed to be mounted like in an easily accessible area of the airplane. So the last set of wires that come out of an ESC are the leads that go to your receiver. They get plugged into the throttle port on the receiver. And electricity from the battery is ran through this lead to power the receiver and all the servos in the plane.

[00:39:10] So if you remember from our receivers episode, we talked about how the power bus bar on the receiver could take input voltage from any of its servos parts or any of its servo ports. So you don't necessarily need to have anything plugged into the battery port if you're running an electric setup. However, you don't have to use the BEC to power your radio. And if you have a bigger airplane, you can't use the BEC to power your radio. So BECs aren't designed to handle a lot of amps.

[00:39:39] A lot of them are in the 2 to 3 amp range, but there are some that'll handle more than that. But if you have a bigger airplane, you're going to want to power your radio equipment with a separate flight battery, just like you were running a nitro engine. If you do it that way, it will be set up just like a nitro engine with the engine and fuel tank separate from the radio gear. So the fuel tank in this case would be the big battery powering the electric motor.

[00:40:05] And actually, Tom, your Kristen Eagle is set up that way, right?

[00:40:09] Yep.

[00:40:09] That's what you said before.

[00:40:10] It is. Yeah. I have a 4.8 volt NIMH pack to run the radio. And then I have a big, six cell pack that actually really only powers the motor.

[00:40:20] Yeah. So even though you have a fully electric airplane, you have to charge and take care of the flight battery the same way you would any of your nitro planes. Exactly. If you really don't want to have a separate flight battery, you can use what's called a UBEC or a UBEC. And those are universal battery elimination circuits. So, really, all battery elimination circuits are just voltage regulators.

[00:40:43] It's just taking the higher voltage and taking it down to the voltage that's usable with our receivers without, blowing them up. So, these separate UBECs can handle more current than the ones built into the ESCs.

[00:41:01] So it's kind of like taking the BEC out of the ESC, blowing it up, making it bigger and more capable and just housing it outside the ESC.

[00:41:09] Yeah. It's just separating the electronics.

[00:41:11] But it's still powered by the same flight battery. You don't have to power a UBEC with a separate battery.

[00:41:16] Correct. Yeah.

[00:41:17] So UBEC is taking a place basically of a flight battery, but it's getting its power from the big main pack.

[00:41:22] Yeah. It's still taking the power from the main pack. So when you solder them together, you're going to have to solder two leads onto each one of your battery connections or your battery terminals on the connector. And that, like I said, for bigger airplanes, for ones where you don't want to be limited by the small current or the small amount of current that you get from your BECs, it's easy enough.

[00:41:45] Just set one of those up and you don't have to worry about two batteries.

[00:41:48] Or if you don't want the weight of a receiver battery, you just pop one of these UBECs in there and hopefully your flight battery has enough to power your motor and receiver and servos and all that stuff at that correct amperage.

[00:42:01] Yeah. So if you wanted to get rid of your battery, you could just get one of these. I absolutely could. I could get it in your BEC.

[00:42:06] Yeah. But I like the safety of having that flight battery in that airplane. It's a nice airplane.

[00:42:11] That's true. Keeping stuff separate is a little bit safer. Although there's a lot of other things that could also happen.

[00:42:18] Well, that airplane, though, I mean, has four servos just for the aileron. So there's four, and these are not the nine-gram servos either. These are, I forget what high-tech servo they are, but they're not a high-voltage servo, but it's four analog servos drawing power plus, the rudder and the elevator servos. So, that's six analog servos pulling power. I don't want to pull that power away from my six-cell motor battery.

[00:42:44] I want the performance of that electric motor,. So the extra little bit away to that 4.8-volt NIMH pack is minimal compared to what performance I may lose with the, taking that power away from the flight pack.

[00:42:58] Yeah, but the draw really on that battery, you won't notice a difference running that limited amount of servos. They're pretty small.

[00:43:07] Okay.

[00:43:07] But you can do it however you want, obviously. It's your airplane.

[00:43:11] It's good to have options.

[00:43:13] It is. But anyway, so most of the BECs built into ESCs are only good up to about a 3S LiPo. They're pushing that now. you're able to get some that are going to be able to work with bigger batteries. But really, they have a hard time getting that voltage down, dissipating that heat, making it work with the high voltage going down to a lower voltage, going all the way down to the five or six volts that it puts out. I think most of them are five volts.

[00:43:42] But so if your ESC has a BEC and you plan on powering your receiver with a flight battery or a UBEC, you have to cut the positive red wire that goes from your ESC to the receiver. Leave the other two wires alone, but you want to cut that red one because you don't want two positive sources of electricity going to the electronics. So some ESCs have brakes on them. The brake is normally able to be switched off and on in the programming.

[00:44:11] Sometimes the brakes or the brake is used on airplanes with foldable props like for glider pilots and, the ones that turn off their motors when they want to glide. So ESCs for RC airplanes usually also have a built-in safety feature that will turn off the electric motor once the battery gets too low. But it's going to continue to power the radio and servos through the BEC. So this is called the low-voltage cutoff, or LVC.

[00:44:36] Some ESCs are programmable and can be set to different voltages, and some are set from the factory and can't be programmed. It's really a better idea to fly with a timer and use the safety feature as a last resort. But it's a nice feature to have to save your LiPo batteries from accidental over-discharge without turning the whole airplane off. Yeah, I agree. Yeah, so let's take a look at a speed controller I have and see what it says. So it's an inexpensive Hobby King ESC.

[00:45:06] It's labeled with HK-30A ESC. It has a big 25 printed on it with a small 30 and subscript below it. It says cells 2-3S, auto-detect, max current 30-amp, BEC 3-amp. It doesn't say if it's for a brushed or brushless motor on the label, but we can figure that out by looking at it. Since it has three wires on the motor side, we know it's designed to run a brushless motor. If it only had two wires on the output side, it would be for a brushed motor.

[00:45:38] So now that's a lot of information that's on the label, but it's important information to understand. So first off, the HK-30A ESC. This is the model number of the ESC. Now, not all speed controllers will have model numbers on them, so if yours doesn't, that's okay. The big 25 printed on it is telling me what its constant current rating is. So it's going to be a 25-amp current rating for constant output.

[00:46:08] The subscript 30, along with the max current info printed on the label, tells me that it has a 30-amp burst rate. So for a short burst of time, 15 to 20 seconds-ish, it can handle 30 amps without being damaged.

[00:46:22] The label also tells us that it is designed to be ran on either a 2-cell LiPo battery or a 3-cell LiPo battery, and it can auto-detect which one is plugged in so it knows when to enable its low-voltage cutoff, since obviously the low-voltage cutoff will be at different voltages between 2S and 3S LiPo batteries.

[00:46:41] So what if you get a speed controller that doesn't have any labeling on it at all? So for example, I've got an example. you order a speed controller off of wherever you like to order speed controllers from, and it comes in a package, right, a Ziploc bag or some kind of stapled package, and on the package has all the information you need, right? It has all this stuff that you're talking about.

[00:47:07] But then, you pull the ESC out of the package, and the speed controller, comes from China, made by the lowest bidder, whatever, and it's got shrink wrap on the whole outside of it, but no markings on the outside of it. The markings are on the package, right? So you put it in an airplane, and you fly, and you're, you have a great time.

[00:47:25] And then you sell or trade or give away or whatever said airplane to a friend, another hobbyist, whatever, and he or she flies that airplane for a little while, and then they trade it, and then it gets traded or sold or whatever again, until finally it ends up in my hands, and I'm looking at it.

[00:47:46] And you want to turn the whole Susanna off?

[00:47:48] There's nothing on the outside of the speed controller to tell me, or is there, what it's capable of, what it's max, what it's max.

[00:47:58] Okay, so let me cut you off there. Okay. I'll give you a quick answer. Thank you. Nope.

[00:48:03] Fair enough. You are, your guess is as good as anybody else's on that. At that point. So, obviously, it's not going to tell you who made it. It's not going to tell you anything like that.

[00:48:13] So, for anyone listening who has a speed controller that comes out of a package like that, do guys like me a favor, and just take a little ultra fine point sharpie and write on the shrink wrap of the ESC some of these numbers to help.

[00:48:26] Or better yet, just tape that little piece inside the airplane.

[00:48:29] Oh, that's a good idea too.

[00:48:31] Or, better yet, just keep it at home and don't get rid of your airplanes.

[00:48:35] Well, there's that. But, I mean, they…

[00:48:37] No, I get it. And, in all honesty, like, the motor that you have in that, you can see what it is.

[00:48:44] Right.

[00:48:45] What kind of current draw you're going to need. what kind of batteries it takes. You can replace the ESC if you need to.

[00:48:51] Understood. Because they are cheap. They are, absolutely.

[00:48:54] I mean, they're dirt cheap. So, really, like, with that one, you're just going to have to figure it out or deal with the tune. I mean, it's kind of catchy.

[00:49:06] Because I know that's why you want to know what it is. No, it's catchy, all right. Okay. Okay. It's going to catch on fire one of these days.

[00:49:13] Whoa, whoa, whoa. That might be a little too much. All right. I'm just teasing. Just buy a new ESC. Anyway, so, one of the other things that we've been asked often is whether or not you can use the same speed controller for brushed motors as you can for brushless motors. Hey, even I know the answer to that one. I'll take it, Tom.

[00:49:33] 90% of the time, the answer is no.

[00:49:36] And I'd say it's a little higher than that. It probably is nowadays. 99% of the time, the answer is no. Yeah. Why is that?

[00:49:43] Well, believe it or not, back in the car days, when the brushless motors first came on the scene, Novak Electronics actually produced speed controllers that could do both. And Novak wasn't the only manufacturer. But, yeah, they could be, they could be configured, if you will, to run brushed or brushless.

[00:50:00] Yeah. And I actually think I have one of those.

[00:50:03] I think I do still have one also.

[00:50:06] But for, in general, I will be comfortable saying generally no. Yeah. You can't. It's not something you're going to deal with on a daily basis. And, that's because the brushless motors work completely differently than brushed motors. And they, the brushed motors require a very specialized speed controller to drive them. Yep. Brushed motors run on DC, the direct current. And the brushless motors are the three-phase AC synchronous motors.

[00:50:37] So, just no. Yeah. I'm going to leave it at no. We'll just say no. So.

[00:50:44] Cannot use a brushed speed controller with a brushless motor and vice versa.

[00:50:48] Correct.

[00:50:49] Okay.

[00:50:49] They are completely different beasts. So, let's move on.

[00:50:54] Okay.

[00:50:54] Now that we have, now that we've kind of talked about brushless motors and all that fun stuff, ESCs, let's talk about how to select a motor. So, let's kind of put it all together and let's see what kind of electric setup we need for our airplane. So, remember the garden hose thing we were talking about earlier? Mm-hmm.

[00:51:17] So, we'll use that analogy again to quickly walk us through the steps we're going to do to figure out what electric motor we need, what battery we need, and what speed controller we need for the airplane. Yes.

[00:51:30] Folks, listen up. This is good stuff. I've kind of already been through this a little bit and it helped me greatly. So, old school guys like me, listen up. Seriously.

[00:51:41] Okay. Here we go. So, first thing we need to know, we have to figure out what the motor size needs to be. And we'll talk about how to figure that out in a minute. Okay. But once we know the size of the motor, we will have a starting point for the rest of the setup. So, for the water hose analogy.

[00:52:00] Okay.

[00:52:00] Let's say we need to fill a one-gallon bucket with water every minute to do whatever it is that we need to do.

[00:52:06] Got it.

[00:52:07] So, now that we know what our goal is, we can work backwards to figure out the rest of the equation. Does that make sense?

[00:52:13] It does. Yep. So, you want to know what you want your airplane to do, basically. And that's going to help you figure out where to start.

[00:52:20] Yeah. Got it. And you're going to start with the motor. So, after that, the next thing we need to figure is how much pressure we need from the spigot. Going back to the garden hose thing. We're going to figure out how much pressure we need from the spigot to do that. And remember that the spigot pressure is going to be our voltage from the battery.

[00:52:40] So, the last thing, then, that we're going to need to figure out is what kind of hose we need to get to be able to continually supply that water at that pressure. Got it. Or we'll have to figure out how many amps our speed controller needs to be. Yep. So, without knowing what the end goal is, we can't pick any of the components of our system. Exactly.

[00:53:01] You wouldn't use the same water hose or pressure from the spigot if you needed to fill a 55-gallon drum in 30 seconds as you would if you wanted to fill a one-gallon drum in one minute. Right.

[00:53:10] That just wouldn't work.

[00:53:11] Right. So, let's talk watts for just a minute. Okay. I've seen watts.

[00:53:18] I've seen them in advertisements for motors and things like that.

[00:53:21] Yeah. And that's a handy thing to know. Unfortunately, not all of them don't watts. Right.

[00:53:26] Here we go. Standardization again.

[00:53:27] So. Or lack thereof. Yeah. So, what are watts, and how do these numbers relate to the capability? So, watts are, in electrical terms, voltage multiplied by amps. So, the higher the number, the more powerful the motor is going to be. So, think of it kind of like a car motor. The more power, or to get more power out of one of those, basically, you need to be able to get more fuel through the engine to burn. So, more cylinders, bigger displacement.

[00:53:59] The watts are a bit like that. The higher the wattage, the more power the motor makes. But it's also going to drain the battery, or your fuel tank, faster. So, you're going to need a higher capacity battery in order to get a longer flight.

[00:54:12] Yeah.

[00:54:12] It's a compromise. Yep. So, we start with picking the right motor for our airplane. To do that, we need to know a couple things. Let's use my Cavalier for an example.

[00:54:22] Okay.

[00:54:23] So, the first thing we need to know is the weight of the airplane. Easy enough. Go out to the website and find that. So, according to the manufacturer's website. Well, it's not completely built yet.

[00:54:32] Oh, well, true.

[00:54:33] So, that's difficult to do. It is. Plus, actually, weighing it is going to be a little bit more difficult because weight is going to be like the all-up weight of the airplane. Oh, I got you. Including the motor that you have not yet selected. Including the motor, the ESC, and the battery. So, going to the manufacturer's website. Or, if you already have the plane, look in the build directions. It'll tell you what its final weight is going to be.

[00:54:54] So, according to the directions with mine, it's going to weigh between five and a half and six pounds. So, I'll go on the heavier end just to be safe and use six pounds for the calculations. You build heavy. I build well.

[00:55:10] So, once the weight, the next thing you're going to do is figure out what kind of flying you're going to be doing.

[00:55:15] Okay.

[00:55:16] So, there's an old-fashioned general rule. And this is going to be an important one that you're going to want to remember. And, actually, I haven't brought this up yet, and I probably should have. Everything that we're talking about now is going to be on the website. Wonderful. So, this is all going to be in text over on the website. So, just head over to rcplanelab.com, click on the link for the electrical motors.

[00:55:38] I would probably refer to that from time to time.

[00:55:41] And we'll kind of go through this.

[00:55:42] Because what you're getting ready to cover is really good stuff.

[00:55:44] Yeah, it's very handy. Like I said, it's what I used when I was building the Cavalier to figure out stuff before I bought it. So, an old-fashioned general rule. Trainers are going to be about 80 watts a pound. Sport flying, which is really what I like to do. not anything too aggressive. It's going to be about 100 watts a pound.

[00:56:07] Sailplanes, depending on what kind of, what you want to use for your rate of climb, are going to be anywhere from 80 to about 150 watts a pound, is a safe guess. It's a big range. It is a big range. But, like I said, it depends. Depends. If you want to go up slowly, you don't need as much power as if you want to go almost vertical. Right. Obviously not vertical, but that would be funny seeing a sailplane go straight up there.

[00:56:32] There are some out there that can.

[00:56:34] I still haven't gotten mine down yet. Actually, there's quite a few out there that can. Oh, are there really? Yeah. I still haven't gotten mine down yet. I still want to get that out of the shop and play with that one, but that's coming up. Anyway, so back to this. 3D flying is about 200 watts a pound. EDFs, 200, 300 watts a pound. They're very power hungry. Yes. Yes, they are. So, not all manufacturers stick with these numbers exactly. Right.

[00:57:01] They're not hard and fast rules.

[00:57:03] No, but they're good numbers to aim for as a minimum when you're picking a motor combo for your airplane. Like, just to check myself, I went out online. I did find some airplanes that were, being sold as RTFs and stuff. And trainers, I found a couple of them. One was 95 watts a pound. One ended up being like 111 watts a pound. So, it's right pretty close.

[00:57:24] But as hobbyists, in modern times, we tend to overpower our airplanes anyway.

[00:57:30] That's true. And this was also foamy airplanes. Right. So, they're going to be a little bit lighter for the size of the airplane. And easier to overpower. True. Than like if you build out a balsa.

[00:57:41] Right.

[00:57:42] Okay. But anyway, so I want to fly in a sport type manner.

[00:57:46] Mm-hmm.

[00:57:47] So, I'm going to aim for the 100 watts per pound.

[00:57:49] Okay.

[00:57:50] So, first thing you have to figure is you take those 100 watts per pound and you multiply it by the six pounds the airplane should weigh. So, I will need a motor, doing that math, 100 times six, that is capable of producing 600 watts. Give or take,. And the other thing you want to consider is your prop RPM. So, nitro engines, give or take, spin around 10,000 RPM in the air. That's a lot of give or taking. Well, what do you figure?

[00:58:18] Well, no, that's… 10,000 about what you figure for a nitro engine?

[00:58:21] In the air, it depends on the… Depends… I mean, there's a wide range, right?

[00:58:25] Well, okay.

[00:58:25] But, no, I would say for these purposes, yeah, if your Cavalier is spinning a 10.6 prop at 10,000 RPM in the air, then regardless of whether it's being spun by a nitro motor or an electric motor, it's going to get the same performance. So, yeah, I think 10,000 is a good, in this case, a good figure to use.

[00:58:46] Okay. Which is how I figured this. So, great.

[00:58:51] So, you just got confirmation. There you go.

[00:58:53] You're welcome. That's what I want. But, anyway, so, since we know, electrical equations, such as P equals VI is what we're going to be using now. So, we know that P is power, which is measured in watts, and V is the voltage, and the I is amps. So, P equals V times I. So, watts equals volts times amps. And that's what we're going to use here in a little bit. I just want to touch on that really quick.

[00:59:23] So, unfortunately, you can't just Google a 600-watt RC airplane motor and find the motor you need. That would be so nice if you could. But you can't. So, after digging around online, I found a couple motors that I wanted to look at a little bit closer.

[00:59:38] Okay.

[00:59:39] So, the first thing I found was an E-Flight 4250 brushless motor, 540 kV. Unfortunately, it gave me no specs. Nothing was listed under this.

[00:59:51] Except for the 540 kV.

[00:59:53] Yeah, but that doesn't tell me anything. It doesn't really tell you much. That tells me how many times it's going to spin per volt, but it doesn't tell me anything about how much power it's going to be able to produce. So, no wattage information, no amperage, nothing. Okay. So, that's out. That one's gone. Forget about it. The next one I came to was a Tomcat G46 5020-680 kV Outrunner. So, let's look at this one a little bit closer. So, you got the specs for this one.

[01:00:18] That one had the specs on the website. Nice. First off, what's nice is straight up on the website, it says that it's comparable replacement for a 46 glow engine. Done. So, perfect. Yeah. That's, if you can find something like that, you're in good shape.

[01:00:33] You're golden. But, let's go on. Not always.

[01:00:35] Yeah, I like it that way. It says that it's also rated at 900 watts max. So, that's higher than the 600 we're needing. So, far, looking good. So good. Okay. Let's do a little bit of math and see how this motor works for us. We want our propeller to spin at 10,000 RPM, give or take. Since the motor we picked is a 680 kV motor, we know it's going to spin 680 RPM per volt.

[01:01:04] So, to find the volts for the battery, we're going to take the RPM we want and divide it by the RPMs per volt of the motor. So, we're going to take 10,000 and divide it by 680. That takes us to 14.7 volts is what we need. So, a 4S LiPo is 14.8 volts. So, that works out perfectly. Now, since we know that P, or power labeled as watts, equals Vi, or voltage multiplied by amps, let's figure out how many amps the motor will draw based on the power we need.

[01:01:39] So, we have our wattage requirement at 600, and our voltage is 14.8. So, remember, P equals Vi, and since we're looking for amps, we'll switch that around, simple math, to P divided by V equals I. So, watts divided by volts equals amps. 600 watts divided by 14.8 volts equals 40.5 amps. So, according to the spec sheet, the motor can handle 42 amps of continuous current. So, we're good there, also.

[01:02:09] Okay, yeah. Now, before you go on, so getting back to the KV rating of this motor, that rating is based on no load.

[01:02:20] Yes.

[01:02:21] Do you factor anything in for that? I mean, because you're basing your calculations on a KV that is no load.

[01:02:33] No. I don't. Okay. And here's why I don't. Okay. I'm also using nominal voltage for the battery. True. So, you're going to get a little bit more out of that when you're at full voltage. Absolutely. Everything has a little bit of fudge factor in it. So, really, and I, like for me, I'm not going for a whole bunch of performance. I'm not racing. I'm not doing anything like that to where it's necessary that I get an exact requirement.

[01:03:00] So, this is just for me how I pick, a brushless setup for my airplane.

[01:03:05] Okay.

[01:03:06] You could dig a lot farther into it. I'm sure. And get more in-depth.

[01:03:11] And part of the fun of it is trial, trying new things.

[01:03:14] Yeah, trial and error. Propellers and things like that. Yeah.

[01:03:16] Which is an adjustment you can make. If you should happen to pick a combination maybe that's not perfect, you still have that option of changing the propeller size or things like that that you can kind of make up for probably.

[01:03:30] Yeah, that's true.

[01:03:31] Or putting a bigger battery or whatever. Yeah.

[01:03:34] Yeah, you're right. So, anyway. Okay. So, the next thing we want to do is pick the battery that we want to use. To do that, we're going to need to know what flight time we want to get out of it. So, normally, and this is personal preference, I like to fly for about seven minutes or so.

[01:03:49] Me too.

[01:03:50] Anything longer than that, your neck starts to hurt. I get the shakes. Yeah. Anything less than that, you're like, really? It's over already? So, seven minutes just seems to be a good number for me. So, to find the capacity the battery needed, you're going to take the time and multiply it by the current and divide it by 60. Remember, all this stuff is going to be on the website. So, come on over and look at it because I know just talking about it, it's hard to understand.

[01:04:17] Anyway, so, seven minutes at, let's say, 40.5 amps divided by 60 is 4.725 amp hours, or 4,725 milliamp hours. Since I usually like to only fly batteries to about 80% of their capacity, we'll do a little bit of math here, and 4,725 divided by 0.8 gives us 5,906 milliamp hours. So, a 6,000 milliamp hour battery will fly this plane for seven minutes under full throttle. Keep it in mind, under full throttle. Right.

[01:04:52] Yeah.

[01:04:53] Most of the time, you don't fly. Rarely do I fly around at full throttle for an entire seven minutes. Right. So, that gives you more room on top of it. Yep. Which I like. So, when we do a quick search for a 6,000 milliamp hour 3S LiPo, I see one that has a 25C continuous discharge with a 50C peak. So, 25 multiplied by six, because remember, 6,000 milliamp, to figure that out, you multiply by the amperage.

[01:05:23] 25 multiplied by six is 150, so that means the pack can supply 150 amps continuous, and 50 multiplied by six is 300, so it can supply 300 amps in short bursts. Now, since we're only pulling 40 give or take amps out of it, that battery is going to work perfectly. Yeah.

[01:05:43] And I just got to say, if you're going to pull 300 amps out of a battery, you better have some serious wire and connectors.

[01:05:51] Yep.

[01:05:52] It's just not, we just don't do that.

[01:05:55] No, and that's another thing, too. So, don't ever lengthen the battery lead on your ESC. They're made specifically size-wise and all that to handle that amperage from the battery.

[01:06:12] That's a really good point.

[01:06:12] So, if you make it, because remember the voltage drop thing, and then the amperage goes up and all that, and that's a good way to have a problem.

[01:06:20] It changes the specs of the ESC if you do that. Yep. Yeah, so just, yeah. Leave it alone. Leave it. Don't do that.

[01:06:26] Just don't do it. Just make it work the way it's supposed to work.

[01:06:29] Okay. So, let's move on. Now we're going to pick an ESC. All right. Most of the time, your motor specs are going to tell you what amperage ESC to get. Easy peasy. Yep. On the motor spec page, it's going to give you a max current that it's designed to handle. In our case, the max current is 60 amps. A good rule of thumb, I like to have about 15% overhead. So, just in case,. So, 60 multiplied by 1.15, because that's how you do the, 15% overhead.

[01:07:03] Multiplied by 1.15 is 69. So, 70 amps or an 80 amp speed controller will work perfectly. It's always a good idea to go a little bit bigger on the electronics and smaller. That way, you have some wiggle room just in case you need it.

[01:07:19] And usually, the bigger, going from, say, a 70 amp to an 80 amp speed controller, sometimes they get that extra capacity by going to bigger components, like bigger wires, bigger transistors, bigger, just able to handle more current. So, it's therefore more efficient. And therefore, you can get more amperage through it.

[01:07:38] Yeah, that's correct.

[01:07:40] Never a bad thing to go up a little bit if you have room, so to speak. Wiggle room.

[01:07:46] Yeah, absolutely. It's always better to overbuild than underbuild and have a problem. So, that's about all for picking, like, an electric setup for an RSV airplane. I hope I explained it well enough to kind of have people understand it. If I didn't, I'm sorry.

[01:08:01] No, I think you did a good job of explaining it. But what will help will be, like you said, I didn't know you were going to do it, but having it on the website will definitely be helpful, too.

[01:08:10] Yeah, that's going to make it a lot easier.

[01:08:12] And use your Cavalier as an example because a lot of old school guys like me know what that is.

[01:08:18] Yeah. So, I'll probably just pretty much listen to what we did, what we talked about and all that and kind of transcribe this episode and put it over there. So, we'll see. Sounds good. Let's kind of go over the last steps really quick. Okay. So, we started out by figuring the wattage needed for our airplane. And remember, we multiplied the weight of the aircraft by the amount of watts per pound recommended for the type of flying we wanted to do.

[01:08:42] And that was in that little chart.

[01:08:44] Yep.

[01:08:45] We found a couple motors to consider. Then we made sure the motor would work for what we needed by checking its KV to see if it would spin the propeller at our desired RPM.

[01:08:55] Yep.

[01:08:56] Then we figured out how many cells we needed for our battery. Then we figured out what capacity battery we needed to fly for the amount of time we wanted. And then we picked the correct speed controller to round out the setup. So, there's a lot to it, I know. But that's pretty much all you do. So, last thing. So, if we're going to convert, like if we don't have a fresh plane to start with and we have a nitro plane, we want to convert it over to electric, not a lot to it.

[01:09:24] So, if you're going to convert a nitro-powered airplane to electric power or EP. So, if you see planes that are labeled EP, by the way, that just simply means electric power. So, after you follow the steps we talked about, for picking the right setup, there's really not that much that goes into switching out the motor and the electronics. Yeah.

[01:09:44] It's easy.

[01:09:44] Yeah. Obviously, you're going to pull out everything of the frame that was used for the nitro engine. So, the engine comes off, the motor mount comes off, the throttle servo comes off, all the linkages come off, the fuel tank comes out, all the plumbing for the fuel comes out.

[01:10:01] So, when it comes to mounting your shiny new clean electric motor to the front of your airplane, you can either buy a pre-manufactured electric motor mount or make your own, which is what I prefer to do. You're going to need to measure the standoff distance so you make the propeller, so you make sure the propeller sits at the same distance from the firewall as it did when it was hooked up to that dingy, dirty, smelly old nitro motor. Stop it.

[01:10:24] I did that just for you because I know how much you like nitro. So, anyway, so after you have the distance measured out from the propeller to the firewall, you can measure how long the motor mount needs to be and just design one. They're not all that tricky. And since we're going electric, they're really not going to be subjected to the high vibrations that a nitro engine produces. So, they need to be strong, but they don't have to be that strong. Does that make sense?

[01:10:47] It does.

[01:10:49] You're going to need to find a place to mount the ESC and a place that's easily accessible to mount the battery.

[01:10:53] How important is it to get airflow over the ESC?

[01:10:56] It's fairly important to get some airflow. It doesn't, like, you want some air to be rolling over it, but you don't need it to be mounted, like, right by the engine. It's not going to take as much cooling like as you would with a nitro engine.

[01:11:09] Okay.

[01:11:10] It's going to produce some heat depending on how you fly, but not as much. And once again, if you oversize things a little bit, they're not going to be working close to that limit.

[01:11:19] So, they're not going to be producing as much heat. Right.

[01:11:21] Right. So, they're going to have an easier time doing it. you also need to mount the battery. So, depending on the airplane you have, you might want to cut a hatch somewhere because with nitro fuel, it's easy just to have a little fuel plug place that you can just fill it up. Batteries you have to physically put in.

[01:11:45] And usually, if you can, it's a good idea to try and put the battery where the tank was just because that's going to kind of help with your CG. Speaking of CG, I can't stress it enough. It is imperative, important. You have to. Did I say you have to? You have to. You have to, yes. Recheck the center of gravity and make any necessary adjustments. Right. So, the weights of the nitro gear versus the electric gear aren't going to weigh exactly the same amount.

[01:12:16] So, the CG is going to change and it has to be addressed. Yes. Absolutely. Or else you're going to have problems.

[01:12:21] Or you're going to have issues.

[01:12:23] Bad issues.

[01:12:24] That are not related to the electronics.

[01:12:27] So, was that fun? I'm finished.

[01:12:29] Yeah. Like I said, when we got started, I actually learned a lot. I've not been looking forward to doing this episode. But having done it now, and thank you for doing all the research, I understand a lot better now. I just still come away with it lamenting the fact that the manufacturers don't standardize how they advertise all of their products. Specifically, motors.

[01:12:58] Yeah, and it's kind of like, if we took, or if we compare these to the nitro engines, they're kind of doing the same thing. And it's not, I guess, that big of a deal if they would all do the same thing. So, like with the Power 46 motors and stuff that you can buy, they're not telling you exactly what the specs are.

[01:13:22] Yeah, there's no KV on it. There's no…

[01:13:24] Well, there is KV, but there's not, like it doesn't necessarily tell you amps and all that stuff. Which is kind of the same way that a nitro engine does. It doesn't necessarily tell you bore. It doesn't tell you stroke. It doesn't tell you a lot of the information. Or does it? Not that I've…

[01:13:43] Oh, well, no. Not all of them.

[01:13:47] So, they don't tell you necessarily horsepower, which is kind of the watts. one watt. I'm sorry, one horsepower is what, 746 watts, I think, or something like that.

[01:13:58] Most of the more mainstream, for lack of a better word, those performance figures are usually out there. If they're not advertised with the engine, you can usually go to their website. I know OS has got all of their numbers posted, for all their new engines and things like that. And so, and Clarence Lee, my…

[01:14:25] By the way, did you order a motor yet?

[01:14:27] He, when he was writing the… That's not what I asked. The… I'll get to that. When he was writing the, the… Gosh. What are they called, when you take a product and you review it? Oh, the reviews? Yeah, thanks. When he was doing his engine review and his engine clinic and all that, he would always… He had a dynamometer. He would actually put the engines to the test and put them on his dyno and they would have performance figures.

[01:14:54] And they were all standardized because it would adjust for, temperature conditions and all that. So it was all very, very standard, which my brain likes. But yeah, getting to what you're talking about, not every manufacturer puts those performance figures out there and their board stroke and all that.

[01:15:12] Yeah.

[01:15:12] But you can at least measure them.

[01:15:14] Well, that's true. And I guess technically you could measure the rotor and stator magnets if you needed to.

[01:15:21] Yeah. But how do you measure efficiency?

[01:15:24] Oh, that's true. On an electric motor.

[01:15:26] What I'm saying?

[01:15:26] Well, that's kind of the same as they… You're not necessarily told, how long you're going to fly on a certain size motor. like how efficient does it burn the fuel? Right. It doesn't tell you what its burn rate is. So, it's kind of the same thing. So it's just, it's a different animal,. So we'll get through it as electricity or as electric motorisms.

[01:15:51] Actually, I think electric stuff is going to kind of rule the world before long because it's just so much cleaner. But I think as the hobby progresses, they're not necessarily going to standardize it, but probably going to make it a little bit easier. And as they start telling you watts and all that kind of stuff, that's really the number that I'm most concerned with. All right. Anything else?

[01:16:12] No, that's… I think you did a great job. Thanks, Ron, for, like I said, doing all the research on that.

[01:16:18] I learned quite a bit. Yeah. Well, it's stuff I just had to brush up on because, like I said, when I picked all the electronics and stuff for the Cavalier, I had to go through this before. So no problem. I hope it made sense. And I hope I explained myself well.

[01:16:35] And if you have questions, once again, you can always message us or you can email us.

[01:16:40] All right. With that, I'm finished. Yep. That's all I got. And I will say until next time, good night. Good night.

[01:16:47] Hope you enjoyed this episode of the RC Plane Lab podcast. For topic suggestions, to ask questions, or to give any feedback, connect with us at rcplanelab.com. Or email us direct at either ron at rcplanelab.com or tom at rcplanelab.com. You can also text us or leave us a voicemail at 818-351-9846. Please subscribe, rate, and review us on your favorite podcast app. Until next time, may your landings be gentle.

[01:17:20] The higher your amps, the bigger your hose. Sorry. The bigger your hose, huh? This is why it works better when we're not in person. I still would have laughed, but I would have been quiet. So, anyway, yeah. The higher your amps, the bigger your hose.

[01:17:45] Sorry. It's the 10-year-old in me. I can't help it. All right. All right. I'm good this time. Do it.

[01:17:55] Okay. So, the higher your amps, the…

[01:17:58] You can't do it now, can you? Maybe there's another word you could use. Hose. No, that's it. That's hose.

[01:18:10] Man, we're hosed. So, the higher your amps, the bigger the garden hose. Right. Resistance is… You had it! You had it! This is easier when you're not here.

[01:18:25] Well, I can duck behind the…

[01:18:26] Over here. You're still here.

[01:18:28] Is it better if you can't see me? You're still here.