Know How... 117 (Transcript)
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Father Robert Ballecer: Welcome to Know How! It is the Twit show where we bend, build, break and upgrade. I’m Father Robert Ballecer.
Bryan Burnett: And I’m Bryan Burnett.
Fr. Robert: And For the next 45 or 15 minutes we are going to be…
Bryan: Making fools of ourselves.
Fr. Robert: This is a big quad copter episode. Originally we were kind of going to spread this out but we’ve had a couple of emails from fans who are like this is nice and all but we really want to get to the build. So what we are going to do is we are going to actually give you two of the segments that are going to tell you about motors and propellants so if you wanted to do your own build you could at least get the frame together and then follow along with the wiring of the electronics.
Bryan: We’ll give you the knowledge.
Fr. Robert: We will give you the knowledge in the knowledge hole. Before we get to the whole quad copter power thing there is a little story I want to talk about. I covered it in a couple of my other shows but I am so excited that I want to talk about it.
Bryan: This is exciting. I remember when we talked about it a few months ago.
Fr. Robert: Back with project loon. So the idea was that Google was going to float a bunch of weather balloons. Over areas without Internet access so that you could get high speed rural access bounced off of these many satellites.
Bryan: It was a Google X project right?
Fr. Robert: It was a Google X project and the RND for Loon was supposed to develop a tech knowledge he that would allow you to take a weather balloon with a couple of smarts. And a set of radios for Internet connectivity. It uses a tank of helium to raise the balloon to about 20 miles up. So it is well up in the stratosphere. The funny thing about getting something up that high is it viewed just increase and decrease the pressure at the helium inside of that balloon, you can make it ride the air currents back and forth.
Bryan: Because there are opposite air currents and so it will float between. Which I didn’t remember this from before but they have like 100 day life span. And then they come back down.
Fr. Robert: Exactly. A lot of these balloons, you could get maybe 30 or 40 days off of them. But Google figured out that if you carefully control the amount of helium that is used and if you use those air currents for station keeping you can get 100 days or more out of a single tank of helium.
Bryan: That is pretty cool. That is a lot of time.
Fr. Robert: There were a lot of issues with it. It was a cool idea but it was very much a pie in the sky. They tried in the New Zealand and it works but when you actually did the math and you thought about putting hundreds of thousands into it on a global scale it wasn’t feasible.
Bryan: At what they are doing now is they are going to do it in conjunction with Google fiber?
Fr. Robert: Yes. They are now taking the lessons that they learned from project loon and they are rolling it into something that they can deploy inside cities. This last week Google filed letters with the FCC asking them if they could start trials on a high-speed wireless service inside Menlo Park and Mountain View, CA. now here is the difference. We had wireless municipal systems before. But what this is going to do is it is going to combine three different types of wireless arrays into a single device. So you’ve got 5.8 which is just what you would have in your dual band router. It is better than 2.4 GHz in that it is not as congested and it is faster but it is not as easy to interfere with as 2.4 GHz but it does not have as much penetrating power. Along with the 5.8 GHz they are going to have a 24.2 GHz. This is the ubiquity of radios that are already in project live. It is the same ones they were using. So you can get about 13 km of range and 1.4 Gb per second of data transfer. Then the third array is what is called a millimeter wave radio. It is 71 to 76 GHz. Incredibly fine wave length. It doesn't penetrate much that you can get ridiculous distances. You can get about 25 km and you can get at 210 Gb per second on a single link. And you can bond multiple links. So what they could do is that if they made enough of the use of arrays they could spread them out throughout the city and then anchor them to where ever they have Google fiber. So instead of having to run Google fiber to every house you would run into like every neighborhood and then you have one of these setups that spreads it out.
Bryan: Like a little beacon. And that is the huge cost prohibiting thing is the actual installing a fiber in certain areas.
Fr. Robert: Exactly. You’ve got to remember when you want to install fiber into a city that is already been built like San Jose or San Francisco, you have to dig up streets. Digging up streets is slow and tedious and requires a lot of permits and a lot of money. What if you could just take it to a single point in that neighborhood and then it is all wireless above ground from there. Basically, once you've got that fiber you could deploy a wireless network overnight.
Bryan: That sounds like a way more efficient way of doing it.
Fr. Robert: Way more efficient and also it has a lot of redundancy. Because once you’ve got these tri-arrays set up on buildings and towers you now have the ability to create a mash network. Which means it is actually more disaster resistant. Biber gets cut all the time but if you’ve got enough of these deployed over a city you’ve just link up with the other arrays and have your mesh back.
Bryan: Very cool.
Fr. Robert: So I’m looking forward to this and just think this all started with balloons. Go figure. Now when we come back we are going to be talking a little bit about your feedback. We’ve got to bits and pieces from the Google community and then of course all this. We are going to tell you how to choose your motors and how to choose your propellers, but before that we need to talk about our first sponsor of Know-How. And that’s got to be SquareSpace. When you are thinking of the one stop shop for everything that you need to put on the Internet, you go to SquareSpace. What is SquareSpace? SquareSpace has been the place that I’ve been using to put all of the institutions that don’t normally have an IT staff on the internet. If you’ve got a portfolio, if you’ve got a set of photos, if you got a great project idea, SquareSpace is where you want to go. Now SquareSpace is always improving their platform with new features, new designs and even better support. they’ve got a beautiful template, 25 of them actually, that you can choose from when you are first creating your site which means you don’t have to know HTML, you don’t have to know anything about CSS, you just choose what looks good and your content fits into it. They also include a logo Creator tool which is a basic tool for individuals and small businesses with limited resources to create a simple identity for themselves. It is easy to use, incredibly easy. But, if you want some help SquareSpace of life chat and email support 24 hours a day seven days a week. Plus there is a completely redesigned customer help site for easier access to self-help articles and video workshops. If you are interested in e-commerce never fear because that is included with your package. Now available for all subscription plan levels, SquareSpace is going to give you the ability to accept donations, which is good for nonprofits. It also is just eight dollars a month so it is not going to break the bank. This is not some service that you are going to be paying pretty much everything that you have, putting all of your budget into just displaying the idea. You get to save most of your resources for developing your idea. SquareSpace is eight dollars a month and it includes a free domain, which means you pay once and you get service everywhere. Now, it is mobile ready. Which is important if you’ve ever created the site because it means that you are not going to have a different experience on a laptop or a desktop or a phone or a tablet. It automatically adjusts for whatever device the user is using. And it gives you the tools that you need like SquareSpace Metric App for iPhone and iPad to check your site stats like your page views and unique visitors. With a blog app you can make text updates, tack and drag images to change layouts, and monitor comments on the go. Which means you are always creating and you are always getting out there. Even their code is beautiful. This is important to me because I don’t want to use a surface that just takes a good luck but Dan has absolutely horrible code behind the scenes. If you look at the code that SquareSpace generates for you it is clean. It is neat. It is beautiful. In other words it is elegant. SquareSpace takes care of the hosting with that one be so you don’t have to. This is what we want you to do. We want you to start a free two-week trial with no credit card required and start building your website today. When you decide to sign up for SquareSpace make sure to use the offer code know how to get 10% off and to show your support for know-how. We think SquareSpace for their support of know-how. A better web awaits and it starts with your new SquareSpace website.
Bryan: We are going to talk about the motor is now right?
Fr. Robert: So we talked about the frame last time. What are you going to choose? We've got a couple of different frames here. We’ve got the 250, the sub 250, the trainer that we been telling people to get. Then we've got this which is a 450. And then this is the DJI that Twit had. I’ve been working on it. It was in pieces in the basement. This is sort of like a 350 or so. an
Bryan: Remember this frame you are saying is not that much…
Fr. Robert: Actually this is a good thing. If you look at these frames, these two are much closer to each other than to this. On both of these frames you have a central frame and then you hang everything off of it. All the electronics and the motors. On this one, there is no central frame. It is a shell and you put everything inside of it.
Bryan: And without the top it doesn’t have a lot of structure integrity.
Fr. Robert: If I try to fly this right now without the top it would snap. You need to complete thing. Whereas this, the strength comes from the frame. We are not talking about frames right now though we are talking about motors. When we talk about motors there are a couple things that we want to know about them. First of all we need to talk a little bit about what a brushless motor is. Because these are not the motor is that we use for project lunchbox.
Bryan: Right. These are smaller.
Fr. Robert: The technology is slightly different. So when we are playing with brushed motors which is what we used on Project lunchbox, we had a central core that rotated a round of permanent magnets. That central core would use a coil that you could charge to change the polarity of the magnetic field being created by that field. As we know, if you have like poles they will push away from each other and if you have dissimilar poles they will attract each other. So you just keep flipping it back and forth and that is what…
Bryan: Generates the power.
Fr. Robert: Right. But with the brush motor it is different. They brushed motor the permanent magnet is actually stationary. The Armature is driven by the current. In other words we get the can that moves rather than the central war. So the motor is actually driven by the outside of the motor. This shows you what the inside of a brushed motor looks like. We’ve got the 1740 and Inside you've got that stationary set of field magnets, coiled magnets. If I run current through that I am going to generate a field. But look at this ring. These are our permanent magnets that are going to be both propelled and attracted to the different quails as they engage their magnetic fields. If you do that, thousands of times a second you can get a lot of rotation out of your motor. Which is absolutely fantastic. The nice thing about a brushless motor is that it is going to live longer because there are no brushes that are going to wear down. There is also going to be less maintenance. A little easier to maintain. They are more efficient because there is less friction because there is nothing touching the commutator. It also decreases the amount of electromagnetic interference generated by the motor.
Bryan: Which would make it less efficient?
Fr. Robert: Yes. Anytime you are generating heat or EMI you are actually decreasing the efficiency because that is energy that is being pushed somewhere else rather than into the motion of the motor.
Bryan: Then what are the disadvantages?
Fr. Robert: The disadvantages of a brushless motor it tends to be more expensive, it tends to be more complicated because you saw with the inside looks like. And it is slightly more prone to damage. Brushed motors are really robust, you can slam them, you can crush them and they will still keep going. Brushless motors you’ve kind of got to take care of.
Bryan: I’m fairly certain the motorcycle that I reviewed, the eBike, was brushless.
Fr. Robert: Absolutely. You are going to want brushless because it is more efficient but you cannot paint on it like you can with the brushed motor. The technology is really approaching parity where it is not as if one is super delicate and one is not that you should keep that in mind. There are two types of brushless motors that we are going to use for aquatics. You are holding one of them. This is what is called an Outrunner. And Outrunner is low RPM’s, So low revolutions per minute the higher torque. That is also direct drive. So another words I am going to go ahead and take one of these propellers and I am going to attach it directly to my shaft. Which has a bunch of advantages. It is a much simpler system. It is a quieter system. But there are also others. All of our trainers are actually using what is called Inrunning brushless motors. You will notice that each motor here actually runs through a gear. You use a really high rpm but very low torque motor that drives a reduction gear that is connected to the propeller. This is actually more efficient than out renters. And you get a wider selection of props because, since I am using that reduction gear, I can keep any prop in its golden zone a whole lot better than a direct drive. That is just one of the things about mechanical gears. You also get that wider selection of props. It is also very noisy. These are tiny little motors. Typically we don’t use Inrunners, we like to use Outrunners. That is the way to go.
Bryan: I guess because it doesn’t make a lot of torque so it’s better for the smaller props? Because as you get bigger you have to have more torque?
Fr. Robert: We will talk about that. As a rule, the faster a motorist spends the more it efficient it is going to be. That is one of the things that we have learned about motors. Especially brushless motors, which is if you spent a faster you are going to get a lot more of the electrical energy turning into mechanical energy. The slower it spends it is not as efficient but you are going to get far more torque. If you think about it like an electric motorcycle. The starting torque was ridiculous right?
Bryan: And then as it got to a higher RPM it kind of petered out?
Fr. Robert: It starts to peter out. You don’t get as much torque but you do get much more efficiency. So it is one of those reverse curves for a gas motor where you start with a lot of torque and then you go to increased efficiency. Where a gas engine will start with very little torque and then moved to improved efficiencies until it starts going back down. Now, also Inrunning motors are very very fast. But they do provide little torque. So this is just something that you should keep in mind. Essentially we are only going to use Inrunners on the trainers. Now let’s go by the numbers. When we start talking about motors the first thing that you are going to get is what is called the kV. That is the critical number of times the motor turns for every volt that you supply it. So in reality the number is going to be slightly less because that motor is not 100% efficient. But this is the Turnigy 1704-1900Kv Outrunner. That means when we give it 11.1 volts it will turn 21,090 times per minute. And it increases for every volt that we give it. We like to have those high efficiencies. Because it is a smaller motor and because it does turn faster, this is kind of ideal for 250 classes and when you have a motor that includes the bullet connectors like this, it makes it a lot easier to install. This one is the Neewer A22112. It is a 13Kv1000 Brushless motor. That means when we give it 11.1 volts it will turn 11,100 times per minute. It is a bigger motor so it is going to turn slower, which also means it is going to generate more torque, So I can turn bigger props. This one is a Emax MT2213, 935 Kv. Now when we give it 11.1 volts it will turn 10,378.5 times per minute. Again, slower torque and still the same engine is that Neweer which means slower rotation speed which means you’re going to have more torque. All that means is that the larger the motor that you choose, the bigger the prop it is going to be able to carry. When I use something like the 1740’s here, these are only going to be able to drive may be 4 to 6 inch props. When I start moving up to something like the Neweer here, this Neweer is going to be able to drive anywhere from seven, eight, may be ten inch props. And then the Emax here, this Emax could actually drive 12 inch props if I really wanted to. So, That is a nice little smattering of props. Here is the problem when you are trying to choose a motor. Aside from the KV, every motor will give you it’s Kv rating. How many times is it going to turn per minute when you give it a volt. They are not really detailed. The numbers that they include before the Kv, they really mean nothing. Outside of that line. Within that manufacturer they may mean the bigger the number, the bigger the power you get. But it is really nothing. One of the things you do want to find is if the motor includes max thrust. What is the max thrust? For example the max thrust on this Emax is 150 grams. Ideally what I want is I want at least a 1.5 to 1 thrust weight ratio. So if I know that this things weighs 1 kilogram, than I need 1.5 kg of thrust just to get it into the air. It is going to perform horribly but that is what I need. Ideally what you want is something closer to 1 to 2 or 1 to 3 ratio. This does a 1 to 4 ratio.
Bryan: You were telling me about the test you did where you started from the ground and just see how high you could get it in a short amount of time. And you lost it in the sky for a little bit?
Fr. Robert: Yeah. Because I was so used to playing with the trainer. You really can’t get into trouble with the trainer. So I turned this thing up and I had to do some lazy hovering and I jammed the throttle. I was on the football field in the end zone and it was in the other end zone in about a second and a half. It is just like racing. If you can put more power into a smaller frame that weighs less, you have a better power ratio and you can do more things. Now, we've got people in the chat room you are saying okay so why don’t I just put the biggest motor that I can into the smallest frame? You could do that. We are actually going to talk a little bit about that. That here is a few things to remember about choosing your motor. First, you need to choose your shot. Take a look at the motors that we’ve got here. This is the Neweer. This is the DGI one, the one that came in the quad copter. This is the Emax, which is about the same size. Then we’ve got this, which is the 1704. If you notice the shaft size differs and the shaft length differs. That is going to affect what kind of prop you choose for your quad. If you use the skinny on in the middle, you are going to need some sort of adaptor to hold the prop to it. This on actually has a long screw on it which means I can put basically any prop and I’ve got enough leeway there to fasten it down. Again we are going to see the newer one here. The newer one uses a spinner hub from an airplane that allows me to fasten up to 12 inch props on it. I wouldn’t want to run that off of the Neweer. Shaft size is going to be one of the first things to consider. Do I want to have to run an adaptor or do I want to direct connect it? The second thing is size it to your frame. This is a direct answer to the people that asked if they could take the big motor and put it on this. If you have a 250 size frame, then you are going to want a smaller, faster spinning motor. The reason for that is that smaller props can be incredibly agile, but you need to spin them incredibly fast. These smaller motors tend to have much higher RPM, just lower torque. Also if you put a big motor on this you are actually hurting the power to weight ratio because you are wearing the thing down. Because I can only spin this prop so many times before I am no longer getting any effect. So it is not just get the biggest prop, biggest motor and go. You’ve got to size it appropriately. If you have a larger prop you are going to want to go with a larger can that spins slower but provides more torque because you are going to have bigger props which will need more force to turn them. Now, the third thing is feedback. I would believe feedback more than I would ever believe any number the manufacturer would give me.
Bryan: You are talking about like Enthusiasts Forum?
Fr. Robert: Got to the Enthusiasts Forums and see what works for them. Again, the specs lie all the time. On paper, this Neweer engine looks incredible and it is a piece of crap.
Bryan: For people who have already tested it they found that?
Fr. Robert: Yeah. Look at the Enthusiasts Forums and find out what they are using. They are really good about their specs. Someone will say, I used a 250 class frame and I’m using 22/12’s rotating with a Kv of 2000. If you like their build then build that motor and prop combo.
Bryan: Okay, that makes sense.
Fr. Robert: The last thing is to choose the bullet connectors and wires for you. There are different size bullet connectors. This one is a 2.5 and there is also 3 mm bullet connectors. There are also bare wires. This one has no bullet connectors on it at all.
Bryan: So would you have to solder that then?
Fr. Robert: Yes. So this one needs to be soldered. This one can be solder less but only if I get speed connectors that have the same bullet size. I’ve seen a couple of people do builds and they buy all the stuff and then get home and it is different size bullet connectors. So if you are going to do your build, plan on making sure that everything is actually going to come together. Especially if you are not handy with the soldering iron, make sure you get the same size bullet connectors.
Bryan: These little motors are really well put together.
Fr. Robert: They are incredible. Actually those are my favorite. Those make the 250 just scream. No when we come back we are going to be picking up on props. Because now that you know how to choose your motor we are going to tell you how to pair a prop to it. Remember this episode is all about power. But before we do that, we want to take some feedback.
Bryan: From the Google Plus Community. And the first one was someone asking for help building a NAS. and so he was looking to build a new low-power server. He is currently using a D510, mini ITX board with 2 GB of ram, 2 TB of hard drive, a mini ITX case, the main purpose for it was to have file sharing, backups, media streaming through Plex with a couple of desktops, laptops, XPMC, and there is new hardware he’s looking for with an AMD 5350, Asrock AM 1HITX mother board with 4GB or 8GB or RAM and 4 TB WWD red drives. And he still debating on a case. He is currently using Ubuntu as a server and he loves it. Question is: “Should I install an OS with an SSD or USB drive or just install all 4 drives and install the OS1 of the two terabyte drives? Would there be an advantage to running an OS from an SSD or USB drive?”
Fr. Robert: I know where it is coming from his work that we did on the Free NAS build where we ran the OS off of a flash drive. Which actually works quite well. What I would say Adam is this. I love where you are going. I love the that that you are using the red drives, the fact that you are using decently spec hardware, because remember the faster the processor the more memory you give it within the more the operating system will be able to give back to you. Especially if you are going to run something like Free NAS. Now this idea of where should I installa the OS? This has always been a debate. If you are going to be using Free NAS, it is a no-brainer. You install it on a flash drive. Why? Because it just loads and then it very rarely goes back to that drive. So you just need that feed at the beginning of the boot. Installing it in either an S SD or a hard drive would just be a waste of space.
Bryan: Right. And you are also saying when you install it to the USB habit inside the case were it is not going to get knocked off.
Fr. Robert: Now, if you are actually looking at building your storage server but you are going to be using a OS that can do other things and if you think you are going to make it do other things, then absolutely 100% I would say use an SSD drive. You can get a small win just for the operating partition but the benefits of having an SSD is going to be fantastic. Especially if it is not pairing the operating system along with one of the drives that is supposed to contain your data. There are going to be people out there that say overkill. And normally I would agree. If he is going to install Free NAS, which is such a small OS and doesn’t have a lot of two-way communication I would just go ahead and put it on a USB drive. But in this case because I don’t know what operating system he is going to use and it sounds like he wants to build a server that can do storage and probably a lot of other stuff, I would say use an SSD. The problem is that I believe you are actually going to run out of SATA ports. IM not sure but if you have not yet bought your motherboard, what you can do is get one of the ones that has the eSata connector on it, it looks like a PCI slot on the mother board. You can buy small SSD’s that are about 54 GB and install on the motherboard. The nice thing about that is it keeps it nice and neat so that you still only have your storage drives and the bays and the operating system is contained on the motherboard. That is probably the way that I would go.
Bryan: Sounds like the right path to take.
Fr. Robert: We also have one more question.
Bryan: So, Eddie asks,
“Help me sync. Hey guys I’m looking for syncing solutions (MAC, Linux or Windows).
Here’s what I want: server and laptop.
If the file exists on the laptop and server, sync.
If the file exists only on the server skip (don’t copy to laptop but keep on server).
If the file only exists on the laptop, sync.
Bryan: It sounds like you found a one-stop solution for this.
Fr. Robert: I did. This is actually something that I reviewed probably about eight years ago. It has been a really long time since I first took a look at this. What he wants is he wants selective sync. I know there are actually a lot of people who want this. Where Dropbox is no good for you, one tribe is no good for you, because you don’t want to just either sync it or not. You want some sort of logic behind the sync. Let’s forget what he said for a second here and consider that you have a file and you wanted to sync to the cloud if it is contained only on one device. But if it is contained on two devices then don’t sync. It is that kind of logic. Luckily there is a off-the-shelf piece of software that works really well called Good Sync. This is a piece of software that I have played with for a while. The nice thing about this is that it does let you set rules for what it does and doesn’t do. Now whether or not you can get the resolution of logic that you want, it kind of depends on it exactly if you know what you want out of your logic tree. But this does do syncing. Sync if you have this, don’t sync if have that, sync if you have two devices, don’t sync between two devices if you don’t have it. I think this is actually going to work for you. It does have a free trial so try it out and see if it works. It is not that expensive and it is actually fantastic. Good Sync Is one of those pieces of software that I have to pay for something, this is probably the one I’m going to get. Because it works really well with FTP and all the major dropbox, side Drive utilities. It is just a solid piece of software that is very easy to configure.
Bryan: It is nice that it does work with all those different OS’s and mobile too. Very cool.
Fr. Robert: So, there you go. Just pick up a copy of Good Sync or download. Try it out, and tell us if it works for you. If it doesn’t then we will give it another go and I’ll see if I can find something else that will work. But before you judge it, make sure you have the logic tree for what you want to sync and don’t want to sync. Because it makes it easier for you to program your solutions.
Bryan: Cool. So back to quad copters and props.
Fr. Robert: Okay I am going to throw a bunch of numbers at you. Any time you look at a prop there is always two numbers that should stand out. So when you are thumbing through Amazon or Hobby King, there are two numbers that you want to take a look at. Diameter and pitch. Diameter is easy it is from tip to tip, how long it is. This is a prop and this one was an 8 inch prop and then over here you’ve got a bunch of 5 inch props. These are pretty tiny. Now the size is just one thing the other thing that you have is pitch.
Bryan: Which is the angle of the prop itself.
Fr. Robert: Right. So for example, this has a 5 x 3 which is a 5” x 3 the three is the pitch. The picture means that for every revolution of the prop it is going to pull it forward by that amount. So if it is a 5 x 3 it means every revolution of a 5 inch prop it will pull the model forward 3 inches. It doesn’t actually work out that way because it is a good approximation. So these are in a pipe for and I believe that is a 10 x 4.5. So you can get different diameters and different pitches. You can have big props, you can have small props and you can have what are called aggressive props or less aggressive props.
Bryan: Depending on what you want to use it for?
Fr. Robert: Exactly. And now we need to discuss what they are used for. Now, the more angle they are the higher the pitch, and the higher the pitch the more aggressive. The more aggressive, the more top speed you are going to get.
Bryan: And what about maneuverability?
Fr. Robert: Yes you also get maneuverability. But that aggressive pitch also tends to affect the aerodynamic performance. It is not as stable and also it is going to put a bigger drain on your battery. The higher the pitch the harder the engine has to work to turn it which means you are going to be sucking and more current which means you are going to drain the battery more quickly. Now choosing your prop is all about balancing top speed, lift capacity, and power drain. So, the larger my prop, my tenants prop can theoretically lift more than my 8 inch prop on the same engine. Which can lift more theoretically than my 5 inch prop at the same motor. So that determines how much weight it can actually carry. The higher the angle, the higher the top speed of the model. So in other words if I have a very non-aggressive angle. Say I have a 10.2, so tenants prop by 2 inch pitch it will carry a lot. It is not going to draw much power but my top speed is really limited. As fast as I can spin it I’m still only can get that 2 degree.
Bryan: You’re not going to be generating a lot of thrust with it.
Fr. Robert: Exactly. But it is more stable. Now I can also go up and down in pitch and in size and that will change the amount of power I draw. So either increasing the size of the propeller or increasing the pitch of the propeller both of those are going to increase the demand on the motor.
Brian: And in conjunction it will drain more power.
Fr. Robert: The more I demand from my motor the more power it is going to draw from the speed controller, the more power that is going to drop from the battery. So that is what I am talking about in the balancing game. In the chat room they are saying why don’t you just go with a really big motor and a really big prop with a super aggressive pitch. You could do that and you have a flight time of like 60 seconds. And that would not be very fun at all. So it is all about balance. This is not a problem, this is what I like about quiet. I change up my props all the time depending on how I want to fly. If I want a lazy flight I take a medium-size prop with a non-aggressive pitch and it doesn't go really fast but I get to however it and move around. If I am really cranking on this thing and I want to shoot across the football field I will use a 6 inch prop with a 6 x 5 and my battery will be drained but it is crazy how much speed an acrobatic ability I can get out of it.
Bryan: So another question might be are the props more expensive? But are there variable adjusting props?
Fr. Robert: There are. But not really for quads. It is too hard to do it for quads and it is crazy expensive. Something else to remember and this actually puts this whole frame and motor size into perspective. The key to flying a quad is thrust management. Because the thrust is how you get altitude, it is how you lose altitude it is how you maneuver. It is all about thrust. Remember the quad has no wings so it doesn’t glide, it rests on the thrust being generated by its props. Which means, the more quickly you can change between different thrust states the more quickly your model can move and maneuver. So that is why the smaller quads, the one they use for racing is why they use these really small propellers because really small propeller means a very minimal weight. Very minimal weight means I can speed them up and slow them down almost instantly. There is almost no mass. So I can go from zero RPM to the 15,000 RPM in the blink of an eye and then back. Very agile. I can really fine-tune the amount of thrust that I can get. I can really rock the quad back and forth.
Bryan: And you wouldn’t use this for racing.
Fr. Robert: You wouldn’t because now we are using one of these props and when you compare the weight of this to the weight of this, this is going to speed up and slow down so much more slowly.
Bryan: There is more rotational maps.
Fr. Robert: More rotational mass which means it is not going to slow as quickly, which means it is not going to speed up as quickly which means I am never going to get the agility out of a 450 or even a 350 that I can out of a 250.
Bryan: That is so cool though. We have all the different models because each one is kind of a balancing act between how much power do you want and how efficient you want it and what do you want it to do? So these are the ones we play with, they are tiny and fast. The bigger one you would strap a camera to because it is bigger and more stable.
Fr. Robert: Exactly. Now, there is one other factor. You will hear a lot about carbon fiber props. And these are crazy expensive but the reason why people like them is because this is an 8 inch prop and it is the same size as this 8 inch prop. But it weighs half of this. It looks cooler, it is sturdier but the big thing is the weight. If this ways basically as much as this plastic 5 inch prop, that means I can speed this up and slow it down as quickly as I do to this. So I do get a lot of maneuverability back with this, but the downside is these are crazy expensive.
Bryan: And from my experience they chip really easily.
Fr. Robert: Well all of these props chip really easily. I have a box of broken props at home. That is the other thing once you get into this buy a lot of props. Just get props.
Bryan: That’s what you are saying, that you buy them in like eight packs.
Fr. Robert: And remember, this is something we covered early on, on any given quad you have two different types of props. You’ve got the rotating with a clockwise, and the counterclockwise rotation. So, it is not like if you break a prop you can just replace it with any profit in the box. You’ve got to have the right one. So, let’s get the takeaways. We are starting to run out of time. Somebody was looking at buying the props for their motor, again the temptation is going to be to get the largest motor with the largest prop with the most aggressive pitch. And you might think that gives you the most speed, the most capacity and the best performance but not necessarily. That means you are going to be running your quad below the gold band. You really don’t want to do that. It also means that you are killing your flight time because you are sucking power out of the battery. It also means that you are not going to get the throttle management that you want. You may think that goes really fast but it also means it is not going to turn so well. It is not going to increase or decrease altitude so well. It is not about bigger is always better. Sometimes smaller is a lot faster. Since the larger your prop is the slower it is to spend an slow down, it means that if you want agility you are going to want to go with the slower and lighter prop. Now there is another temptation. If I don't want bigger is better what about smaller? You could do that you could get the 250 and get the highest RPM motor with the 3 inch prop. And this thing will fly like a bumblebee, yes it will. It will be crazy fast and crazy agile. The problem is, you are going to miss out on top speed, you are going to miss out on cargo capacity and really high rpm’s create a ton of heat.
Bryan: If these are spinning at 21,000 RPM that is pretty quick.
Fr. Robert: It is pretty quick. And remember heat is wasted energy. I’m sorry we are gong to have to do this to you. We’ll have all the takeaways in the show notes but what it ultimately comes down to is how you want to fly your quad. If you want to learn, what I would suggest is that you get something with larger motors, larger props with less aggressive pitch because that will let you practice your hovering and basic maneuvering. As you get better you can start going with smaller the faster spinning props, faster spinning motors and more aggressive pitches which will give you that agility. Ultimately is going to come down to your comfort level. If you have a set of props on in the model is not moving the way you wanted to move change the props. Now that you know how it is affected you can actually increase in size decrease in pitch or increase in motor rotation. That is all going to affect how your quad is going to handle.
Bryan: The thing I love about these trainer ones that we have been playing with is there is a high and a low setting. So when we are inside I practice with the low setting that when you’re outside on the low setting it feels sort of sluggish. And then when you set it to my it just takes off. And you get to play with it.
Fr. Robert: And we are actually going to talk about that because these more advanced models also have dual stick.
Bryan: So you can adjust how much power.
Fr. Robert: Exactly. So this actually I can flip the switch right here and when I flip the switch it moves it from saying to him saying. So when I go to in saying, essentially what I’m telling you is it turns off the flight leveling and for every movement of this stick, multiply it. Which means it is twitchy. It will slam into the ground without even thinking about it. But it also means it is ridiculously acrobatic. When I put this into an insane mode I can do flips, I can make this thing turned around on one of its props. But, it is dangerous.
Bryan: Does that use up any more battery?
Fr. Robert: Yeah. You are going to use more battery. If you were going high stick rate then you are really revving the engines. So, that is power. Now folks you have a frame. We told you how to choose your frame. We also told you how to choose your motors. And how to choose your props. Next time we have to get into the electronics. We are actually going to show you the smarts on your quad. That is this thing right in between the legs. This is the brain. Once I get my motors and my props mounted they have to be controlled somehow. It is going to go through the electronic speed controllers, to this. And we are going to show you exactly how to choose yours and how to install it.
Bryan: Yet, because then you can add GPS stuff to it so that it has a come home function. All those goodies.
Fr. Robert: This used to have that. I’m pretty sure the GPS is busted.
Bryan: We really put that into the ringer we should’ve had more of these little guys before we ever tried to play with this.
Fr. Robert: Now, before we go we have a parting shot that has nothing to do with quad copters. And we started wondering what happens when you put a bunch of oysters into a tank of really dirty water? There are a lot of oysters in this area we got two tanks with identical murky water. We got oyster’s and one of them and look at this time lapse. You can actually see how much time it is taking and those things clean out all that. And it is really disgusting.
Bryan: They are the filters of the ocean.
Fr. Robert: They are. Which then leads me to think why am I eating oysters? Right?
Bryan: I did think that two, but it is harmless. What if they started ingesting heavy metals or something?
Fr. Robert: Exactly. They will filter everything out of the water. So do I really want to me that after it has filtered everything out of the water? Garbage animals taste the best.
Bryan: I have a follow-up image. We went more in depth with this. See? There is a tank on the left with no oysters and a tank on the right with oysters.
Fr. Robert: Now we know the oysters are delicious and dangerous. They are deadly.
Bryan: Who knew? The harmless oyster is deadly machine.
Fr. Robert: Folks, that does it for this episode of know-how. Remember next week we are going to be taking you through how to integrate these things into the power system. I believe we may be showing off some adobe premiere stuff. Perhaps? We are going to have to celebrate a certain local sports team so we may not have anything for you next week. But, we know that this was a lot of information. I actually have detailed notes on motors and on props. How to choose them, how they relate to one another. Make sure to go two hours show notes page in order to get those. Where do we find those?
Bryan: At twit.tv/kh. And there is also all our past episodes and definitely watch the past episodes on this series. You want to go back and check those out. Padre has been doing a great job keeping track of all the parts and listing everything and their prices. So definitely check that out and subscribe to the show so you don’t miss anything.
Fr. Robert: Remember you can always use those show notes to go back. Because we did give you the parts list. People have been asking what did you buy and why? Everything that we are going to use in this project we have already given you a link to get. It is in that first episode of quad copter build. Also don’t forget that you can find us on our Google plus page. Go to gplus.to/twitkh and you will find yourself part of the community that is like 8000 people. The nice thing about that community is that there is always people who are ready and willing to help you no matter what stage of a build you are in.
Bryan: There are great questions being asked all the time and it helps us see what people are interested in. That is part of the reason why we are going to do more Google hangouts in the future.
Fr. Robert: Postwar questions and we will try to get to them in a future episode. Also don’t forget if you are not into the G plus then you can follow us on Twitter. You can find me @PadreSJ.
Bryan: And I’m @cranky_hippo.
Fr. Robert: Until next time, I’m Father Robert Ballecer.
Bryan: And I’m Bryan Burnett.
Fr. Robert: Now that you know…
Bryan: Go do it!