Mixing, Delta Wing Style.

It’s not exactly a mixing 101 introduction, we’ll hit that topic some other day, but we do introduce the topic of mixing and how it pertains to a combat or delta wing style flyer. That is, a plane that does not have a separate aileron or elevator. They’re combined into one synchronized pair of control surfaces called ‘elevons’.

Elevon = Elevator + Aileron

When a mommy elevator and a daddy aileron reaaaaaaally like each other… No, we’re not going there. Oh, the letters I would receive.

Why do we need mixing at all? If you plug your aileron servo and elevator servo into your receiver and start banging on the stick, you’d quickly notice that only one control surface moves with elevator input and the other only moves with aileron input. Since we don’t have separate elevator and aileron control surfaces, this poses a problem.

We need to mix these transmitter inputs to multiple receiver channel outputs. That’s the quickest way to describe mixing, but not necessarily the most simplistic. Basically, we want moving the transmitter stick in one direction to actually make more than just one servo move. By default, your transmitter only moves one servo at a time if you only move a transmitter stick in one horizontal or vertical direction. Rudders move left and right, elevators move up and down, and so do ailerons.

But we need the ‘ELEVONS’ here, and we need them pronto. STAT. ASAP. There are typically three ways to perform mixing of any style, and we’ll cover two of them here. The first isn’t widely used anymore, but still fun to consider.

Mechanical Mixing

This is the one we won’t be covering in detail. But think of an aileron servo, sitting on rails, and the aileron servo connects to our two control surfaces. Now, picture an elevator servo attached to the aileron servo itself. When you give elevator movement, the control surfaces move because you’re actually MOVING the aileron servo ITSELF. When the aileron input is given, the normal servo arms move the control surfaces as you’d expect.

That’s the kind of rig you’d have to create for mechanical elevon mixing. It’s neat, and I’ve seen it done on small little combat flyers when the pilot didn’t have a programmable transmitter and the servos were embedded on a circuit board. So, not a huge amount of the population would need it. I may try and build one myself someday just to say I did. It’s how I roll here in my RC man cave.

V-Tail Adapter Mixing

So, let’s say you DO NOT have a transmitter that’s capable of mixing built in. Say the park flyer transmitters that come with popular Spektrum bind and fly kits – you know, the game controller looking transmitters. Those don’t have mixing built in for delta wing style, because they’re often attached to planes with fully separate elevators and ailerons.

So what can you do then? Pick yourself up a v-tail mixer device. They’re cheap and online and here are two examples. One here and one here

The wiring for these is really quite simple. The hardware mixer sits between your receiver and servos. You plug your mixer into your aileron and elevator receiver channels, and the servos plug into the mixer. Voila! Instant elevon/delta wing mixing.

Programmable Transmitters

This is by far the preferred method. Most of our transmitters these days are programmable in some way, either by a PC or on the transmitter itself via switches and buttons and big old LCD screen to confuse you. However, this really is the best way to program mixing, as mechanical requires much more building setup and the v-tail mixers aren’t often as customizable as you might like.

As far as your transmitter goes, you want to look in your setup menus for options such as ‘Elevon Mixing’, ‘Delta Wing Mixing’ and the like. They’re typically under setup / adjustment / wing mix menu options. If only I had every single transmitter out there, but I don’t… so it’s hard to describe it in exact menu locations.

What is our goal with this mixing of which you speak?

The goal here is to have aileron/elevator stick movement translate into moving our elevons together in harmony. They shouldn’t be separate. We want Brad and Angelina, not Brad and Jennifer. If that reference is still applicable when you read this, I’m thankful. I would have used Burt and Loni or Ike and Tina but then I’d really be dating myself.

Quite simply though, here’s the final output checklist for your stick movements and what your control surfaces should be doing. If you’re looking at the back of the plane and the nose of the craft is facing away from you:

• Moving your elevator stick DOWN (toward you)
  Both control surfaces should move UP
• Moving your elevator stick UP (away from you)
  Both control surfaces should move DOWN
• Moving your aileron stick RIGHT
  the RIGHT control surface moves up, the LEFT control surface moves down
• Moving your aileron stick LEFT
  the LEFT control surface moves up, the RIGHT control surface moves down

No matter what mixing method you choose, if things aren’t looking like the above, you may need to reverse some servo directions on your transmitter or swap aileron/elevator servo receiver channels on your craft.

Manually mixing with your transmitter

A lot of transmitters offer ‘Programmable’ or ‘User’ mix options. These are for when the built in mixes on transmitters don’t give you what you’re looking for. Elevon mixing is SO common that I’d be surprised to see a programmable transmitter made today that doesn’t have it built in.

However, if you watch the video, we go through creating a manual mix, two of them to be exact. Why? We want the elevator stick input to also move the aileron servo (mix 1). We ALSO want the aileron stick input to move the elevator servo (mix 2). So they’re actually mixing against each other in a way.

So, a brief intro to mixing, targeted towards delta wing style flyers, like our combat flyer. Enjoy!

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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It’s been one heck of a year since Chameleon first introduced us to foamy combat. Slowly but surely, interest grew, and not only did we have TEN combat flyers at the Omahawks labor day air show, but we also had other clubs and individuals try out the combat flyers!

So let’s take a look at some small tweaks we’ve made to the combat flyer over the year, some lessons learned, and some updated plans and 3D views. Since we’ve already covered the Mach One (aka Mark I – our lawyers messed up on that one, if we had lawyers or even a dispute to begin with) in previous articles, we’re just referencing some slight differences here.

Here’s the coverage from the 2010 Omahawks Labor Day Air Show:

I believe that is what they call ‘Potato Quality’. Nevertheless, some of the club members I used to fly with, along with a little bit of ‘RC Combat’ action at the beginning of the news coverage!

Sketchup and Plans

DOWNLOAD!

Our plans have been redrawn in Google Sketchup, and are available as a PDF to download here.

Combat Mach One 3D View

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Mach One Combat Flyer Plans

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Some 3D Views are also available to help get a feel for what this looks like assembled. The biggest change to the plans besides cleaning them up – we’ve shortened the battery block to allow us to move the CG forward a slight tad.

Control Horns: Move em up and swap em out

A fellow club member, E.J. Murphy, noted a mistake I made on the model I built in one of my first videos, so I wanted to make note of it. The hole in the control horn that the control rod fits into is just a bit far back – actually it’s well far back from the hinge line. It’s best that the control horn ‘holes’ line up directly above the hinge line. It ‘calms’ the flyer down a little bit compared to them being too far back.

Also, I’m trying Lexan plastic as not only a control horn, but also a small ‘receiver protection box’. I’m not terribly worried about most of the electronics in the combat flyer except for the receiver – it’s arguably worth more than the rest of the plane combined. Now you can use cheap receivers and transmitters, and that’s fine, but I love my Airtronics SD-10G. It has great advanced programming and customization that the geek/dork/nerd in me just drools over. (It doesn’t come with a drool shield, unfortunately) So, I built a small lexan cover to slide the receiver into – it has to be better than nothing if the errant prop goes KA-CHUNK against the receiver!

Get your Velcro Strap On

The Mach One is a squirrelly flyer compared to the classic trainer, even though it’s the first plane I learned to fly with. However, it’s meant to be squirrelly. This is FULL ON CONTACT COMBAT! Similar to Sparta, with almost the same amount of madness. So, keep the battery attached – make a secure Velcro strap that holds hugs the battery in place – don’t just depend on a single piece of Velcro attached to the underside of the plane. Speaking from experience on that one!

We (Temporarily) Went Pink!

Yeah, it’s Pink. Prior to this, we’ve been using DOW Protection Board III – available locally at our Lowe’s shop. It’s blue, it’s around 1/4 inch thick, and it’s great for cheap foam planes, especially for COMBAT! However, if you’ve worked with it, you’ll notice a wave to the foam, and it’s annoying.

I decided to try something from a Lowe’s competitor of sorts – Owens Corning Pink Board from Home Depot. Still 1/4 inch thick and fanfolded, and while the sheet has a slight curve to the full width, it doesn’t have the waves that annoyed me so much in the past.

It’s a tiny bit more brittle than the blue fan fold from a simple bend test, and it may add 10-20 grams more weight to your flyer, but I love working with it in comparison, so while I’ll still use both, I do prefer… the girlie colored stuff. Thankfully, with some paint and tape, you can de-pink it a bit.

At the end of the day, I like the blue fan fold the best. Waves or not, the pink is a tad heavier and too brittle for combat. Live and learn.

Preferred Prop/Motor/ESC/Battery Combo

After some slight experimentation with props and motors, I’ve found my personal preference to be the following:

EMAX CF2812 1600KV 2-3S Brushless Outrunner Motor

Available from Heads Up RC, this motor has worked great for our combat flyer. Editor’s Note: Heads Up RC closed it’s doors mid 2019.

8×4 Speed Prop

You can certainly use 7×3.5 or 9×5 props with the EMAX motor, but I personally prefer the 8×4 prop. It handles great and gives me the speed I need to get out of some of those hairy combat situations… or into them! Now, the CF2812 is rated as a maximum prop size of 7”, but I’ve had no problems with the 8×4 on this motor. 9×5 – you’re pushing it, and definitely avoid wide open throttle.

18 Amp to 25 Amp ESC

Get some cheap ESCs for your combat flyer – I’ve found some nice programmable ones for my various foamies at hobbypartz.com

1000 to 1800 mAH 3S Battery

While a 2S 7.4 V Li-Po battery works with the above motor – I like the power behind a 3S Battery, and I prefer almost the middle of the 1000-1800 mAH power range – that being a 1300 mAH 3S 11.1 Volt Li-Po. Balances the plane well, I get the power I need, and the flight times are decent. With a 1300 mAH battery, I can float gently around at half throttle for almost 15 minutes. HOWEVER, when in COMBAT! mode, I cut that down to around 5, as you’re really working the motor and servos. Good stuff!

Servos

We generally did use 9G servos, but we tried some little 5 gram units and see how they performed… Well, they performed badly, to say the least. Of course we’re not looking for QUALITY items here – it’s friggin COMBAT after all. But, between quality and the torque from the combat maneuvers, we’ve had better luck with 9 gram servos, so stick with those!

Paint ‘Em Up!

Hopefully you’re not flying these alone… Playing COMBAT! with yourself could be considered lonely and disturbing. So get some friends, but make sure you can tell each other’s planes apart! Dress them up! Foam safe paint, decals, colored packing tape, big thick markers – do what you have to so that you keep them not only separated, but you keep orientation of your craft as well – top from bottom and direction.

Of course, if you add too much tape or paint, you’ll strengthen your flyer up some, surely, but you’ll also add weight. Keep your balance in mind.

Combat and Friends

We’ve had numerous bits of correspondence over the year related to our combat flyers, which has been really great to read and share with our friends. Here now are two great examples of others using the delta wing Combat flyer:

Pantseatflyer

Pantseatflyer built a single blog post on his experience with our Mach One combat flyer, and hopefully we’ll see an update as to how he’s taken out a friend or two, or perhaps the evil squirrel that ran across the field. Pantseatflyer’s Blog

Chino Valley Modeler’s Inc.

The Chino Valley club not only built a combat flyer or two, they held a combat competition, built a large scale version of the combat flyer, and even a DUALBRUSHLESS version! Thanks to Rick Nichols and Randy Meathrell for sending me some great pictures and results of the combat competition, where 5 of the 7 craft were based on the Mach One!

They tried some crepe streamers cut in half to make some of the 1v1 combat jaunts a little easier, about 6 feet of string attached to 6 feet of streamer. They’re even considering trying 12 feet, as the six didn’t make much of a difference to the flight… I can just imagine some video of a prop eating up or getting wrapped up in a streamer… Sounds spectacular!

Between the huge MACH ONE BATTLESTAR GALACTICA CRUISER OF FOAM DEATH(my personal nickname for it) and the dual brushless Mach One setup, they’ve really raised the combat bar!

Check them out at http://www.chinovalleymodelaviators.org/

Our Final Thoughts

That wraps up our Combat: Reloaded segment. A refresher to some changes and tweaks made, some freshly drawn plans, some ideas on power systems and coloring schemes, and even how others have taken the Mach One idea and run with it. Clearly, Chameleon’s design, which evolved over many years, is a hit when it comes to fast paced foam combat action.

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I think RC is fun.

Dad thinks RC is fun.

Dad and I think RC is fun.

I like flying.

Dad likes flying.

We like flying.

I fear like flying with Dad.

Dad likes attempting to decapitate flying with son.

A little levity to break the series videos up a bit.

This is a collection of video segments I’ve had laying around on my hard drive since the start of last year. Four decapitation attempts, from helicopters, to delta wings, all the way to gliders.

I hope you all enjoy the little vignette as much as I enjoyed making it and surviving the filming.

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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Electronic Speed Controllers (ESCs for short) bridge the gap between your battery, motor, and receiver. The ESC takes input from your receiver (while often supplying power to your receiver) to drive your motor with power supplied from the battery. So, ESCs have three connection points – two wires for your battery, a set of wires for your motor, and a set of wires for your receiver.

This article and video will explain how ESCs typically work, looking at an ESC from a power standpoint, and a little bit on programming. Nothing too low level for this round – we’re really looking at points to consider for the power requirements of your circuit and the ESC that best fits your needs.

Types of Electronic Speed Controls

There are two primary types of ESCs, and they MUST match the type of Motor you’re using. It’s quite simple – Brushed motors require brushed speed controls, and brushless motors require a brushless speed control. The big difference here relates to the motor. Not to get to deep into the making of motors, let’s just say that since brushed motors rotate through ‘mechanical commutation’ – where there’s a commutator and brushes that drive your motor to turn, a brushless motor’s commutation is done via electronic signals from your ESC, which allows the motor to be just that – brushless.

This is why brushed ESCs have two wires for the brushed motor, and brushless ESCs have three wires for the brushless motors.

Battery Eliminator Circuits

Either way, if you have a brushed Motor/ESC pair or brushless Motor/ESC pair, you can use the same receiver and battery for either setup. However, there is one thing to keep in mind when you’re choosing a speed control. Whether or not there’s a BEC – Battery Eliminator Circuit – embedded in your speed control or if you need to purchase one separately.

So what’s a BEC? Well, receivers need power too, but they typically need somewhere in the range of 3 to 9 volts (depending on your receiver) to get power. If you’re using a 3S battery (11.1 volts) – you’ll easily fry your receiver if you plugged the battery directly into it. We’re talking the release of that magic blue smoke. That’s bad. Crossing the streams bad.

One option is to simply have a separate battery pack that powers the receiver and servos (which typically get power from the receiver). But… who wants to carry another battery pack around? Receivers and servos don’t take a lot of power for your smaller park flyers, carrying around a second battery pack to power your receiver and servos is cumbersome and only to be used when necessary.

A Battery Eliminator Circuit drops down voltage for your RX!

Enter the BEC. BEC’s are basically voltage regulators. They take a high input voltage and output a lesser voltage. This is what lets you plug in a 11.1 volt lipo and only let 5 volts out to your receiver and servos. Even then, there are two types of voltage regulators that BECs typically employ – linear and switching. Voltage regulators need to drop the voltage somehow. Linear regulators do this by dissipating heat. That means it will get warm, even hot, as it steps the voltage down to a level the receiver can handle. A switching regulator, on the other hand, rapidly cycles the power on and off, which makes it generally more efficient, as it doesn’t have to dump power in the form of heat.

You could dive more into that detail, but just know that those are your two types of regulators – which means two common types of BECs. Where you use one over the other often comes down to some gritty electronic details, so mostly… just make sure you have one IN your ESC or you get one to wire TO your BEC-less ESC.

A lot of ESCs you’ll find have a linear BEC embedded inside the shrink wrapped package. This works well, it’s all together and you have less wiring to worry about. However, let’s think about what we just discussed about heat. If I have a speed control that supports 6S batteries, that’s 22 volts that the linear regulator has to step down to 6 volts. That’s a lot of power a linear regulator has to dissipate as heat compared to say a two or three cell battery (7 – 11 volts).

In or Out?

This is why you’ll typically see higher capacity ESCs have a switch mode BEC or nointernal BEC at all. When you don’t have a BEC embedded with your ESC, you’ll need to supply one yourself and wire it in your circuit. What typically happens here is that your battery connects to both your ESC and external BEC, and your BEC outputs to your receiver for power, and your ESC outputs to your receiver for throttle signalONLY. (When you have a BEC embedded in an ESC, your throttle control and power to your receiver are combined into one set of wires)

Once again, this is typically necessary for larger RC circuits, but it’s not uncommon to see an external BEC in smaller circuits as well. A lot of your park flyers or 200-400 size helicopters are using 2 or three cell lipos, so it’s not often a consideration. Regardless, there it is for the time you decide to step up your circuits to larger voltage and amperage needs.

So now we’ve covered the two types of ESCs – brushed and brushless, and BECs – external and internal, and also switching vs linear.

Choosing the right speed control (for you) from a power standpoint

In your entire RC circuit shown here, you have a constantly changing equation you must balance to make sure you don’t over tax one part of your system. However, since the ESC is typically taking all of the current from the battery, it needs to have the highest amperage rating over any other part. You can always go higher in amperage on an ESC to be safe, but you can never go lower. But what is ‘lower’? Lower than what?

Lower than the maximum amperage you’ll be pulling through your circuit. This is defined by the load on your circuit – which means everything that uses power – your receiver, servos, and motor. The combined amperage pull from those components combined MUST be less than your ESC’s rating.

So look at this example here, if you have a motor that is rated at 18 amps maximum current allowed, and say the servos and receivers will take no more than 1 amp, you could get away with a 20 amp speed control. However, I like to play it a little safe for a few reasons, and would go with a 25 amp speed control. Remember, the ESC rating can always be higher than you need, at that point it comes down to an issue of weight (higher amp ESCs weigh more, of course). One thing I generally keep in mind is that if you crash and your throttle is up, this can cause an amp spike through your circuit – so a 25 amp ESC would have a chance to handle that better than a 20 amp ESC given the power requirements of this circuit. (We also keep that in mind with plane-on-plane combat, where your prop is a weapon.)

Of course, we need to make sure the battery can safely discharge that many amps, and in our case, it can. 20 amps continuous, 24 amps burst, so we’ll be safe here. That’s why the general rule of thumb is ESC Amp Rating must be greater than safe battery discharge, which must in turn be greater than load on the circuit – RX, servos, and motor amp pull combined.Once again, this time with feeeeeeeling. Make sure the total load of your circuit – all amps from servo, rx, motor, etc. are LESS than the rated amps on your ESC!

Now you can see why a watt meter is so nice when you’re calibrating your circuit – you can rev up the motor, move all the servos, and use the watt meter to see how many amps you’re really pulling through your circuit.

If you change any parts of this circuit out, you need to make sure the rest of the circuit can handle it. Say I put a bigger motor that can pull 30 amps. Well, now I need upgrade my ESC and battery to handle the extra load. Always keep that in mind. Change one part of the equation, and you need to balance it out.

Speed Control Programming Methods

ESCs often have different programming options that allow you to customize how theESC works. There are simply way too many brands of ESCs out there to cover in this article, but we’ll look at a few of the most common methods and options for programming an ESC.

ESCs can typically be programmed through three different methods:

• USB programming kits (Castle Creation’s Castle Link is a good example of this)
• Programming Cards – Small cards or hand-held devices that you plug a 6-7 Volt battery pack and ESC into, pushing buttons to change LED options on the device.
• Throttle Stick Programming – Using your ESC and receiver, you can use the throttle stick on your transmitter to choose options through a set of audible beeps.

Also, keep in mind, that different brands of ESCs can’t all be programmed the same way – you’ll need to read your ESC’s instructions and learn how to program it and which programming methods it supports. Each ESC maker is different.

Speed Control Programming Options

Clearly, programming an ESC is going to be another video and topic, and you can see from this list that some options are more tedious and error prone than others. Now that we’ve looked at how an ESC could be programmed, let’s look at some of the most common programming options. Once again, since ESCs are so different from factory to factory, some ESCs have spiffy auto detection for things like how many Li-Po cells are connected, while others require you to manually set the options.

This list of options is not necessarily related to a specific ESC, it’s a sample of some options your ESC may support. ESCs often also have ‘default’ settings for these options.

• Battery Types – Often defaulting to Li-Po, but can be changed to support NiMH or NiCd batteries.
• Low Voltage Cutoff – Extremely useful for Li-po batteries – this determines when your ESC will cut power to your motor, and whether or not it does this soft or hard.
• Low Voltage Cutoff Level – Protect your Li-pos by telling your ESC to power off your motor if your Li-Po pack goes down to 3 volts per cell, 3.2 volts per cell, etc.
• Brake Setting – Enabled or Disabled – This means if you reduce your throttle, does the ESC tell your motor to spin freely until it stops or to stop turning immediately.
• Start Up mode – Soft or Hard – Hard is often used for airplanes, Soft is often used for helicopters. It all comes down what you’re flying – this deals with how fast the ESC lets your motor accelerate.
• Timing – Low/Medium/High – an advanced setting for brushless motors, related to the signals sent from the ESC to the motor. You can generally use the default, but research your motor and ESC preferences together to know how they should fit.
• Throttle Range – Auto or fixed – This often depends heavily on the model – helicopter or airplane, and deals with how the transmitter throttle stick corresponds to the output of your ESC to your motor.

That’s a taste of your most common ESC programming options, which we may cover some day in a more dedicated article to ESCs. In the end, though, we’ve covered the high level basics but most importantly – the power considerations in choosing the right ESC for the job. Keep it’s amp rating higher than any load you’ll have on your circuit and you’ll be all set!

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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This video/article and the next few will go into a little more detail about the primary players in our examination of RC circuits, those being your Li-Po Batteries, Electronic Speed Controls and Electric Motors. After that we’ll put them all together to look at circuits as a whole, and together we’ll make sense of kV ratings, C ratings, Amp Draw, mAh, series and parallel batteries, thrust to weight ratios, prop sizes, and so on and so forth. We’ll still keep this at a high to medium level, we want to arm you with the basics, and perhaps in the future we’ll dive into extreme detail.

We hope you’ll find this information useful not only if you’re a scratch or kit builder, but also if you’ve bought a ready to fly model and want to understand how the circuits work. Remember that not all pieces of your model will last forever, and if you need to replace a battery or motor, you’ll have a better understanding of what will and what won’t work for your specific craft.

Li-Po Batteries

Li-Po (Lithium Polymer) batteries have been our greatest advancement yet towards everyday electronic RC flight. They weigh less than Nickel Metal Hydride (NiMH) and Nickel Cadmium (NiCad) batteries but supply the same power, so that’s what we’ll focus on here. Li-Po battery packs start at a basic component called a cell, which has a nominal voltage of 3.7 volts. Fully charged, the cell delivers 4.2 volts, and this drops off as the battery is drained. I typically discharge mine to around 3.6 volts, but often you’ll feel a noticeable decrease in power while flying near the end of your pack’s charge – when this happens – land immediately. Discharging a Li-Po battery too far damages the battery’s life span and can potentially be a heat issue. NEVER let a Li-Po pack go under 3 volts per cell. These are the rules of Li-Po batteries to live by if you want a long battery life and want to reduce the risk of overheating or explosion.

How do you know when the battery is drained enough while flying? You’ll notice either by power loss, or you can program some electronic speed controls that have a low-voltage cutoff capability, battery alarm, or use a LVC – Low Voltage Cutoff switch in your circuit. You can also just land occasionally, measure the voltages of your cells, and keep track of how long you were flying. Once you learn the ‘point of no return’ with your battery, you can time your flight and use that as a marker in the future as when you should end the flight and replace the battery.

Larger Li-Po packs are just multiple 3.7v cells wired together to get more capacity and voltage. Let’s break down the most common characteristics of any Li-Po battery you’ll see online with the following ‘fill in the blank’:

(w) S (x) P (y) mAh (z) C

w Cells wired in series,
x Groups of w in parallel,
y Milli-amp hours of capacity,
z Discharge rate.

Total number of cells = w multiplied by x
Maximum amperage discharge: (y multiplied by z) milliamps, divide by 1000 to get amps.

For example, the stock battery that comes with my Blade 400 helicopter has characteristics that matches the following:

3S1P 1800 mAh 20C

Let’s break down the pieces into three parts, cell wiring, capacity, and discharge rate.

Cell Wiring

The S and P stand for series and parallel, respectively. Your most basic battery packs are 1 or more Li-Po cells wired in series, and have no batteries wired in parallel, which is why the 1P is often dropped from descriptions – it’s assumed. Look at this diagram of the same battery in terms of individual cells:

Your smaller helicopters like the Blade mSR and ParkZone Vapor use one single Li-Po cell.

Every time you add a battery in series it increases the voltage by 3.7 volts. So, a Blade CX3 coaxial helicopter, which takes a 2 cell (that is, 2S1P) Li-Po pack, uses 7.4 volts, while the Blade 400, which takes a 3 cell (3S1P) pack – yields 11.1 volts.

Wiring cells in parallel doesn’t increase the amount of voltage, but it does increase the capacity of the battery pack. A 3S2P Li-Po pack actually contains 6 cells, 2 pairs of 3 cells wired in series, and each group of three wired in parallel.

So now you know what the S and occasional P mean when describing a battery.

Capacity

This example battery pack has 1800 mAh hours of capacity available. Think of capacity as your fuel tank – the larger the capacity, the longer you can fly – but also the more weight a battery will have, so it’s another ‘give and take’ example. Since wiring in series like this battery pack doesn’t increase our capacity but it does increase our voltage, each individual cell has a capacity of 1800 mAh.

The term milliamp hour describes how many amps would fully discharge the battery in one hour. Our 1800 mAh pack would be fully discharged in one hour if we pulled exactly 1.8 Amps (1800 milliamps) through the pack (i.e. the ‘load’ on the circuit).

Now, 1.8 amps isn’t enough to really drive a helicopter, so say a helicopter needs 14 amps (14,000 milliamps) to fly properly. This means we’d have only 7 minutes worth of time until the pack is discharged (although you don’t fly to complete and total discharge). You arrive at that value through this equation:

( (Capacity * (0.8)) / Load ) X 60 = Time in minutes until full discharge. Wait… why the 0.8 here? Where did that come from?

Just remember that changing a battery for one with higher capacity gives longer flight time, but also adds weight, which in turn increases your load on the circuit – since the motor has to work harder!

Discharge Rate

The magical “C” rating is defined as how fast you can discharge your battery safely. A higher C rating means you can pull more amps through your circuit before the battery starts taking damage.

You’ll often see a ‘Burst’ rating as well, which of course means maximum power output for say around 10 seconds or so. You definitely don’t want to run your craft continuously at this level of power output.

So what does the C itself mean? If 20 C is our discharge rate, we need to know the ©apacity of our battery to determine the true amp discharge. Take your Capacity and multiply it by your C rating – that is the maximum amperage discharge you’ll want to have during your flight. So, our 1800 mAh 20C battery supports no more than 36 Amps being pulled through the battery safely (Capacity multiplied by ‘C’ rating, then divide by 1000 for Amps) 36 Amps continuously would drain a battery right quick, but you definitely don’t want to go over that amount (especially if that’s your burst rating). Most of the time, you’re not drawing full C rated amperage through the circuit, and if you are, then definitely take heed of the possibility of reducing your battery pack’s lifespan and inherent risks.

However, C rating is often seen as a marketing gimmick, because of course – the higher C rating the better the battery, right?

With that in mind, don’t necessary trust your life with C rating alone. If you have a spiffy enough battery charger you can actually graph and track discharge rates and determine the proper rate for your battery. That’s more than we want to cover here – so let’s generalize by saying take the C rating with a grain of salt, it all comes down to whether your battery manufacturer is honest or not. Always consider a Google search of your battery’s make and model – someone may have already done tests on that specific battery for you.

A great tool for measuring your voltage and amp draw is a Watt meter. This takes the marketing out of the picture. We’ll cover these more in the later RC Circuit articles, but nevertheless they are extremely valuable in determining how much current you’re really pulling through your circuit.

Taking all three of these pieces together, the number of cells in your pack, it’s capacity, and it’s C rating, we hope we’ve armed you with some food for thought when it comes to Li-Po batteries, from what the numbers mean to how much you should safely pull through a circuit.

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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So, we did a little indoor flying, and once again I come up with a novel way to crash or stick my flying wing someplace it shouldn’t be.  Thankfully I had Pop’s Rescue Service available.

Since we often have weather related issues here in Omaha, from thunderstorms to wind, we try to fly indoors when possible. This also serves as a good lunch break for me, and since it’s almost between Pops and myself in location, it’s an easy place to meet up.

I speak of course of the Center, known as The Omaha Sports Complex. Most of the days we’re able to fly in there with little else going on the indoor soccer fields just because it’s during the work day.

Unfortunately, indoor flying just isn’t the same as outdoor flying, and each has advantages and disadvantages. With indoor flying, we don’t have to worry about weather at all, which is great, since wind… well, blows. By taking our combat delta wing flyers inside, we can practice some more and clearly… we need it, due to an inherent disadvantage to indoor flying – ceilings. There are also guide wires at the center which I’ve also developed quite a knack in finding when I least expect it.

So, flying along, I’m getting a bit high up there, and tada… Stuck. I was starting to stall near the ceiling, so my control surfaces were offering little help. In hindsight, I should have killed the throttle. The result is a combat flyer stuck in the rafters:

A stuck combat flyer!

I apologize for the lack of clarity with these photos… Just another reason I need to bring a video camera and real camera every single time I get behind the sticks. First thing I did was kill the throttle of course, and then switch back to high rates, so I had maximum wiggle action in efforts to loosen this foam morsel from the rafter’s teeth.

Alas, wiggle wiggle, wiggly wobbly, and wobbly wiggles weren’t enough. The prop was wedged. Thankfully, they had plastic rings for either some unknown sport of baby-hool-a-hooping or for marking areas of the floor during indoor soccer games and practice.

Pops gives me his delta flyer to hold on to (this moment also commemorates our first at-field epoxy repair, hence why I’m holding a flyer literally ‘together’), while he throws a ring up towards the rafters.

No joy.

Another ring.

Less joy.

Another… Another… Then, five rings at once… Less joy than before, and if you’re counting, we’re well into ‘negative-joy-zone’. Nevertheless, we’re laughing quite often while this is going on.

Finally, after taking just two rings at once, the magic happens, and the delta flyer is dislodged:

Thanks to Pop’s Rescue Service, I have a combat flyer back, with no damage whatsoever… until we continued to fly after the fact and crashed it some more, but that, as they say in Conan, is another story.

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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Dual Rates

This was actually the first transmitter video/article I wanted to create, but I figured we should walk before we run, as even though it’s one of the more exciting transmitter topics to cover, without knowing about creating model memory slots or binding, you can’t effectively work with dual rates and expo.

So, let’s break out the definitions. Let’s define Dual Rate and Exponential as the two primary methods for regulating servo arm throw during flight for purposes of altering the aerodynamic handling of your aircraft. A bit of a mouthful, so let’s ‘break it down’ (hopefully a little better than Michael Keaton in Night Shift). With any of your airplanes or helicopters, from big to small, servos are used for such things as changing the angle of your swash-plate, which in turn alters the the angle your helicopter blades spin at, causing it to change direction, as well as moving your ailerons, rudder, and elevators on your plane to change angle, causing your airplane to change direction.

The movements of your transmitter sticks are relayed to your receiver which in turn controls your servos. In general, moving a stick on your transmitter all the way from one end to another, be it left/right or up/down, also moves your servo from one end point of rotation all the way to it’s opposite end point of rotation. The movement of your servo arm from one end to the other is often called servo throw or servo travel.

Looking at this graph here, we have a simple linear graph of transmitter stick movement and servo arm travel. The actual distance of the servo throw doesn’t matter, it’s your baseline, and that’s what counts. Moving the stick from one point to another moves the servo accordingly, from one end point to another. We’ll use this graph as a reference for the remainder of the article to explain how dual rates and exponential change this graph.

Now, with that said, let’s explain dual rates. They’re called dual rates because transmitters often have ‘hi/lo’ switches to move from one set of rates to another set of rates. Dual rate means you can switch between two settings of servo travel with just a simple flip of a transmitter switch. If your high-rate is set at 100%, that means your servos move 100% of the total allowed arm travel or throw. If your low-rate is at 50%, then when you flip the transmitter switch, the servos now only move 50% of the total allowed throw. So looking at the graph, this red line represents high-rate. We would represent low rate by reducing the angle of the line, which means even though it extends all the way across the line of transmitter stick movement, the amount of servo travel decreases.

Think of your car’s steering wheel. If you could only turn the wheel half as far as you could, you wouldn’t be able to make turns as tightly as you could if you turned your wheel all the way. Same idea applies here.

That’s the general idea. There is no magic dual rate amount from one plane to the next because it ALL comes down to how YOU fly the plane. However, it’s often recommended that beginners use low rates, and if you’re not sure what rates you need, start conservatively. Start off at 65-75% and change by 10% intervals until you’re comfortable. Whittle down accordingly.

Exponential

Exponential and Dual Rates work well together, but without confusing you too much let’s look at Exponential alone with a regular 100% rate. Exponential is the term used for when you apply an exponential curve to our servo throw/transmitter stick graph. What does this give you, in essence? Stick numbing.

Numbing the stick around the center point is a great way to learn helicopter hovering, as you won’t be so apt to fling the helicopter from one direction to another as you learn not only to react to the helicopter’s movements, but predict how the helicopter is going to move next.

So let’s take a look at what exponential looks like on a graph alone:

Follow along the lines. Notice how if you transmitter stick is just barely moved away from center, there is less servo throw on this graph as compared to the far ends. This is what gives you that ‘numb’ feel around the center point, but at the end points it’s just like exponential was never even set – where the curve ‘catches up’ to the end points.

Go back to the steering example we used before. This time, think of loose vs tight steering. Loose steering is similar to having exponential on your steering wheel, you need to really turn it more to start moving, while the opposite is true of tight steering. That’s why it all comes down to a matter of feel. For experienced pilots, too much exponential may make a craft feel ‘sluggish’, whereas a beginner pilot may have their hands full.

Look now at the combination of exponential and dual rates. Building upon all the ideas discussed here, it’s not a huge step, but a fundamental one nonetheless:

All the dual rate changes is the end point travel, the exponential curve stays the same.

The easiest way to feel this before you fly is to just change your craft’s dual rates and expo on your workbench and play with the controls, you can easily see how different the ailerons and elevators work by just watching how far/smooth they move when in one rate or another. A little harder to see with a helicopter, so just be careful with the hovering. 

Why?

Why? What does switching rates give us? There are numerous reasons to change the amount of servo throw, two reasons to consider are training and speed. An experienced pilot may fly a plane at a higher rate of servo throw, as they’re comfortable with the plane and how it flies. Handing that plane to an inexperienced pilot with the same rates could be a disaster, because when we first learn to fly we’re awfully jerky with the sticks… at least most of us are. This makes it awfully difficult to get control because beginners feel the need to correct themselves by moving sticks dramatically from end to end. So, a beginner pilot using the low-rate setting will enjoy a more docile craft for the sake of learning and getting a feel of how the craft flies.

Speed is another reason. For example, the faster an airplane moves, your control surfaces have a more dramatic effect on your flight. Take a plane flying slowly with elevators moving at just 20 degrees from center. Now, double or triple the speed of the plane, but keep the 20 degrees the same. The change is dramatic due to the amount of air now moving over your control surfaces. For this case, then a pilot may have a lower rate setting while they’re really pushing the speed to the limit, so they can still retain control, and use the higher rate (i.e. more control surface deflection because the servo arms move farther) when flying more slowly.

How?

Well, here we come down to the parts that are best represented by video. We have four movies ready for you here, two on the theory of dual rates and exponential, followed by how to set dual rate and expo with both the Spektrum DX6i and Spektrum DX7 transmitters.

Enjoy!

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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Let’s look at what binding does, what model memory is used for, and examples with an mSR, foam flyer, Spektrum DX-6 and DX-7 transmitters.

Here’s the video, and the article follows:

What’s Binding?

Binding is the process of linking your receiver and transmitter together. Each transmitter and receiver have their own unique identifier, like a social security number, except without the identity theft issues. We call this a GUID code – Global Unique Identification. The receiver will remember which transmitter it has been bound to, so that the next time you turn both on, the transmitter and receiver automatically set up the channels to communicate with each other. Rebinding the receiver to a different transmitter negates the previous binding.

So, take a look at this stock transmitter that comes with an mSR or Park Zone Micro Mustang. It binds just like a Spektrum DX-6i, but it only has one memory slot to hold one receiver’s unique ID. This means if you wanted to use this transmitter on a different aircraft, you would have to rebind each time you swapped out your airplane or helicopter. It’s very possible however, to take this transmitter and say, bind it to your mCX, like I have here. This is the stock transmitter that came with a P-51D Micro Mustang, and by following the instructions on the back of the transmitter, I’ve bound it to my mCX.

This won’t work for an advanced 6 channel helicopter, but it does work for any of the craft that use the tiny 5-in-1 and similar receiver units that the Park Zone Vapor, mCX, mSR, and Micro Mustang share. So, in theory, you could buy one of those with a stock transmitter, and then purchase the rest without, and rebind each time, reset your trims, and then fly the craft of your choosing. Since you have to re-trim and rebind, however, the stock transmitters really aren’t that great, and sooner or later you’ll want the control and flexibility of a true programmable transmitter.

Model Memory

This is where model memory slots come into play. The more advanced programmable transmitters like this DX-6i generally have ten or more memory slots to bind with (in this case) ten different receivers, one per model memory slot. Each slot has its own unique settings as well. One slot can be set up for a helicopter, while another slot can be used for an airplane. That’s why model memory is so convenient.

How exactly do you bind a transmitter with a receiver? Well, there are some differences between vendors, from Spektrum, Futaba, JR, and so on, but the idea is very similar. First, you’ll need an empty model memory slot on your transmitter to store your receiver’s unique ID, so let’s set that up now. We’ll create a memory slot for our Blade mSR on a DX-6i and a foam flyer on our DX-7.

DX-6i Model Memory Creation:

• We’re creating a memory slot on our DX-6i to hold our mSR.

• Use model select to find an open model slot. We have an open slot number 8 here, and it’s defaulted to an airplane model.

• Now click the thumb-wheel again, scroll all the way down and select setup list.

• Select model type, and choose helicopter.

• Give your model a name. Scroll down to model name, press your button. Scroll through the letters, assign the characters, and then select Ok!

• Scroll down to Swash Type and make sure you have 1 Servo 90 Degrees selected. This is a requirement when binding the mSR in Helicopter mode.

• Scroll back up to main, and you’ll see we now have the mSR slot configured. Turn your transmitter off with that model slot selected.

DX-7 Model Memory Slot Creation

• We’re creating a memory slot on our DX-7 to hold our foam flyer, an example of binding to a larger transmitter you’ll find on a Blade 400, CX3, etc.

• Hold down your select and scroll down buttons at the same time. This lets you select which model you want to fly. We have a open helicopter slot on 15, so we’ll need to change this.

• Select and Up buttons take you back to the menu, scroll to ‘Type Select’ and select Acro for Airplane. You’ll have to confirm this with your clear key, as it will wipe out any helicopter related settings you may have had in this slot.

• Select and Up again, this time scroll to Model Name and give a name to this slot. We’re using ‘FF’ for foamie flyer.

• Select and Up for the menu again, select model select and you can confirm you’ve now changed your slot to an airplane type with your given slot name.
• Then hit Select and DOWN to actually select this slot for the transmitter to use. Shut off your transmitter with this slot active, as when you enter bind mode, your transmitter will use this slot to bind with your receiver.

DX6i mSR Binding

Now that you have that completed, you must put your craft into binding mode. Spektrum transmitters usually have two different ways of setting a receiver to binding, and it depends on the size of the receiver. For the small receivers used in the Vapor, Micro Mustang, mCX or mSR, you place your aircraft in bind mode by simply having your transmitter off, then plugging the battery into your aircraft. Since the receiver isn’t detecting it’s currently bound transmitter, it will automatically enter bind mode, with a blinking light which basically means it’s waiting for you to down your drink, walk up to the bar, and ask for its phone number.

Let’s bind our mSR. We have a model memory slot created for it on our DX-6i, and the transmitter was last shut off with that model selected, which is the slot the transmitter will use when binding, so make sure it turns on with our new mSR slot selected. With the mSR in binding mode, hold the ‘training switch’ forward while turning on your transmitter. You’ll see the word BIND flashing in your transmitters display and hear a constant string of beeps. Let go of the training switch, and your transmitter is now in bind mode, just like your receiver. Let a few seconds go by, and you’ll see that the blinking LED on your mSR has turned solid, and your transmitter is now controlling your aircraft.

Remember that when you fly your craft again, you don’t want to enter bind mode every time. Therefore, turn your transmitter on FIRST, make sure you have the right memory slot selected, then turn on your mSR. The same goes for your larger receivers as well. Unless you’re binding, your transmitter is the first item to turn on, and it’s always, regardless of binding, the last thing you turn off.

DX7 Foam Flyer Binding (Larger Receiver)

Larger receivers often require a bind plug to put the receiver into bind mode. Bind plugs are usually shipped with a receiver, and for Spektrum models we place the bind plug in the channel marked ‘BATTERY’, or ‘BATT’ for short. Make sure your transmitter is off, then supply power to your transmitter and you’ll see it’s ready to be bound, and in our case the small LED is blinking rapidly.

Inserting the bind plug into the BATT channel.

Now that our receiver is in bind mode, we need to turn on our transmitter in bind mode to talk to the receiver. To do this on the DX-7, push the BIND/RANGE TEST button on the back of your transmitter, then turn your transmitter on. Let go of the bind button (it will flash green), and within a few seconds you should have control of your craft with your transmitter. You can test that generally by moving the aileron and elevator control and see that servos are responding. Remove the bind plug, and power off your unit. You’re now bound… and hopefully not gagging.

Besides binding different receivers to the same transmitter, you can also bind the same receiver into different model memory slots of your transmitter. In case you’re wondering why we would want to do this, consider the case of these foamie flyers. I may have two different foam flyers I use, and I may only have one receiver available at the time. If I setup two different model memory slots for each craft, I can simply remove it from one craft and put it in another, and all I have to change is which model memory slot my transmitter is using and rebind, so keep those bind plugs handy.

Use multiple memory slots if you move a receiver from one craft to another. You still need to rebind though!

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The Transmitter. Keeping you from swinging a rope from your hand to the plane to make it fly. Communicating with the receiver component of your craft, the transmitter relays your commands in order to maneuver your plane or helicopter. Easily the most potentially expensive part of your R/C collection, transmitters may look alike from one to the other, but under the hood they can be completely different beasts.

Here’s the video if you’d rather jump straight to that:

Although we’ll look at various transmitter types in this segment, throughout the series we’ll be diving into more detail with the Spektrum DX6i and DX7 transmitters. 99% of the topics and ideas will apply to other popular transmitters, however, so don’t worry too much about the brand specifics. In the end, it all comes down to translating the ideas to the specific transmitter model you’re using.

You may be intimidated the first time you see one of the more expensive or capable transmitters. When I first saw a DX-6i, I knew forever gone were the days of a coat hanger thick wire hand held transmitter controlling a Dukes of Hazard R/C Car that could only move forward in a straight direction, and it could only turn in… you guessed it… reverse.

Transmitter Parts and Modes

Let’s take a quick look at what a typical transmitter has on it. The most important parts are of course your sticks – they control all the actions of your craft. One of the more interesting differences in transmitters that you may never have to worry about or even hear of is ‘Mode’. Mode 2 Transmitters are the de facto standard in the Americas, while the rest of the planet and solar system generally use Mode 1. We’re really not sure what Antarctica uses, to be honest. The difference in modes relates to which stick performs which function. Mode 2 transmitters have throttle/rudder on the left, and aileron/elevator on the right. In total, there are actually four modes, but modes 1 and 2 are the most popular.

It’s not a deal breaker, but I wouldn’t want to have to switch back and forth, so I look for Mode 2 transmitters myself, as it’s what I’m used to. It’s that simple… if you’re a PC person, you’re more comfortable on a PC. If you’re a Mac person, you’re more comfortable on a Mac. If you’re running Linux you can use whatever mode Antarctica uses for terms of this discussion.

Back to the transmitter. We have our basic controls – throttle for speed and lift,rudder for yaw, which means the rotation of your craft along the Z axis, elevator for controlling pitch, that is whether your craft points up and down, and the final control,aileron, which dictates the rolling of your craft.

Trim switches on your transmitter are for building in fine tune control gestures. For example, if your plane has a tendency to roll to the left when trying to fly it straight, or your helicopter has a tendency to slightly turn on it’s own, you can use the trim to ‘nudge’ your craft without having to constantly hold a stick in a specific direction.

The Trainer switch is used when a training capable transmitter is linking to another transmitter with a special trainer cable. Used primarily when learning to fly at your local R/C club, it allows a newcomer to control a craft under an experienced pilot’s supervision, and if need be, just like a new student driver, the more adept pilot can take control of the craft with their own transmitter.

Rates/Flaps/Gear Switches – They’re more than just for looking cool while you flick switches around in flight. These switches can help control flaps or retractable landing gear on planes, as well as change the whole sensitivity of your craft while in flight. For example, the faster your airplane moves, the more responsive your stick movements will be, so pilots often use these switches to ‘numb’ the controls when doing high speed maneuvers, as stick movements in a more ‘normal’ setting would cause a fast moving craft to be almost too responsive and risky to fly.

In other parts of our series, we’ll be looking at these controls in more detail, and the topic of dual rates is a most interesting one, as it completely changes the dynamic of your craft mid-flight.

Transmitter Communication Methods

Now that we’ve covered the most common switches, dials, and sticks on your transmitter, let’s look at how transmitters typically communicate to your helicopter or airplane. Most of your R/C transmitters will use the four following methods for the wireless communication to your receiver:

Infra-Red – Often used for cheaper helicopter toy models, you’ll need to stay in line of sight at all times to make sure the signal works through. Just like flipping channels on your TV.

AM Radio – One of the early forms of radio transmission, AM radio is very susceptible to interference compared to FM and 2.4 GHz systems.

FM Radio – The former standard for R/C transmitter radio modulation. FM Radios divide the government mandated hobby FM band into specific channels. Your FM transmitter and receiver must have the same crystals for the frequencies to sync up, and it’s these crystals that designate upon which channel you’re operating. This is often the reason that flying fields have boards to post your name and channel number, so no other pilot will use the same channel as you. You’ll often see FM transmitters with large number tags on the tip of the antenna, used to identify which channel you’re on so other pilots can see which channels not to use.

2.4 GHz Spread Spectrum – The new kid on the block, relatively speaking. 2.4 GHz systems generally solve the FM Radio channel issues by using unique digital identification of receiver and transmitter, basically eliminating the need to wait for an open channel or having to endure signal conflicts. 2.4 GHz systems themselves use complex channel switching and overlay techniques, constantly searching for open channels and paths to use.

These systems are not interchangeable, meaning you can’t use a 72 MHz FM transmitter to control a 2.4 GHz receiver. So, what do these different transmitter radio technologies mean? Typically, whichever route you choose (and most choose 2.4 GHz, followed by FM), there are still choices to make. Different vendors have different communication protocols used for the actual data transmission, regardless of FM, AM or 2.4 GHz. This means a Futaba 2.4 GHz transmitter won’t talk to a Spektrum 2.4 GHz receiver. An E-Sky 72 MHz FM transmitter and an E-Flight 72MHz receiver on the same channel still won’t be able to communicate.

Now, there are companies that do offer some compatibility, with either modules that snap in to a transmitter or by subscribing to a specific frequency and protocol. An example of this is Spektrum’s DSM2 protocol, which is supported by Spektrum transmitters as well as select models of JR Transmitters.

The bottom line is that as you get more into the hobby, you may end up getting a collection of transmitters, one for each craft you purchase. This is clearly not ideal, for reasons of storage, ease of use, transport, etc. This is why most enthusiasts end up choosing a radio frequency and vendor for most of their craft.

Transmitter Channels

Common RC Channels

You will definitely come across the term channels when describing transmitters. A channel is simply a single form of control a transmitter can communicate to a receiver. Moving any stick on your transmitter along a single axis uses one channel. So, for typical transmitters, if you have two sticks, and each stick can move up/down and left/right, you’d be using at least four channels.

The more complex the radio or craft you’re flying, the more channels you’ll need. If you have a plane that uses flaps, or bomb bay doors, you’ll need another channel for each of those controls. Helicopters are often categorized in 3, 4 or 6 channel configurations. You may wonder why the need for two extra channels on some helicopters. Well, as you get more complex heli systems, the fifth channel is often used to remotely control your gyro, and the sixth channel is used for controlling the pitch of your helicopter blades. There are 5 channel helicopters as well, usually leaving out remote gyro control and using the fifth channel for pitch.

Keep in mind that not every three channel aircraft is the same as the next. Some three channels may only use throttle, elevator and aileron control, while a different three channel aircraft may use throttle, elevator, and rudder control. These aircraft don’t have all the capabilities of a four channel airplane, but can still be flown – you’d either roll your plane to turn it with ailerons or use the rudder to rotate it.

So what does a channel physically translate to? Well, your elevator and aileron controls (right stick) would use two channels to communicate with two servos. Your left stick (throttle/rudder) would use one channel for a rudder servo (or tail rotor), and another channel to control the speed of your primary motor.

The bottom line on channels is that the more you have, the more you can do. The typical programmable radios that people will plunk down a bit of cash for are at least six channels or more. With a six channel transmitter, it’s a good guarantee you’ll be able to fly any basic helicopter or airplane setup.

Programmable vs. Non Programmable

Most of your RTF (Ready to Fly) kits that come with transmitters in the box include non-programmable transmitters. These transmitters are generally cheaper and with reduced functionality, sometimes only able to fly the craft they came with. If you buy enough ready to fly kits you’ll start building a collection. Sooner or later you’ll be tired of having that many transmitters around, so if you’re just starting and planning on staying with the hobby, do yourself a favor and pick up a programmable transmitter, like the Spektrum DX6i, DX7, Futaba 6EX, or JR X9303.

Programmable transmitters offer two great benefits. The first is that you can fine tune any of the rates or mixing of your controls. If you want to tone down your aircraft’s elevator with a non programmable transmitter, you’ll have to literally shave the elevator on your plane. With a programmable transmitter, the transmitter can tell the receiver to only let a servo go to a certain point and stop, which lets you dictate how responsive your craft is. The other is model memory. Programmable transmitters let you store memory slots for each craft you have. This means – one transmitter can fly many different craft without having to put your transmitter down and pick up a different one. For example, Pops has his DX-6i transmitter with memory slots for his Blade CX2, his Park-Zone Vapor, his P-51D Mustang Micro Flyer, his mSR, his mCX, and his combat flyer ALL tied to one transmitter. Beats carrying around and having to learn different transmitter types for each craft you fly.

Which one do I buy?

As far as which company’s transmitter to buy, well… it’s a Chevy vs. Ford dilemma all over again. I’m not going to promote one over the other, looking at the popular RC forums you’ll see parties supporting each one. I use Spektrum because it’s what I started out with, and it’s what I’m comfortable with. I like it, but you may not. Talk with your local club, ask your fellow fliers what they use. The six channel transmitters aren’t the most expensive things in the world, but you’d want to make sure exactly what transmitter you’ll want if you plunk down over a thousand dollars for a ten or twelve channel transmitter.

The thing to keep in mind is that since different companies make different transmitters and receivers, you won’t be able to easily switch from Spektrum to Futaba without having to swap out all your receivers as well. Sure, the transmitter may not be a bad price, but if you have five craft flying Spektrum receivers, you’ll need to also buy five Futaba receivers to replace them with. It’s just fair warning. It’s not something you’ll have to worry about right away, but once you are onto your third airplane or helicopter it’s something you really should start figuring into your future purchases.

Of course, ARF – Almost Ready To Fly kits don’t typically come with transmitters or receivers, so you’ll have to purchase the receiver that matches whichever transmitter you’re using and go fly.

Another important note is you’ll often see transmitters reference ‘HELI or AIR’ transmitters. More often than not, especially with programmable transmitters, both will fly helicopters and airplanes. The differences are in which default mode the transmitter will have in it’s model memory (you can change that easily), and how the sticks feel. Air mode transmitters have a ratched throttle stick, while helicopter transmitters do not. It’s not a deal breaker, you can use either or, it’s best to have one in your hand to feel it as far as the ratcheted throttle stick goes before you choose.

In the end, we hope this introduction to transmitters and the different kinds available will help you understand a bit better when someone throws the term 2.4 GHz around, or talks about things like four or six channel aircraft.

In the next installment of our series we’ll be looking at binding your transmitter to models as well as model memory!

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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Welcome to the second part of our Combat! Series articles. This article focuses on some finer points of setting up your combat flyer. While enthusiasts that are experienced with electronic flight may find the following information on the backs of their hands, the newcomer will hopefully find the hints and tips useful.

Unfortunately, diving deeper in any of these topics warrant articles in their own right, so with that in mind, we’ll be doing just that! For example, I may do a small write up on amperage and prop sizes in detail, while this article may only cover the simple watt meter / prop size check only. This way we can keep this as a general overview of setup and configuration and dive into details (and hopefully the devils therein) in later articles. I’ll update this article with links to those as they’re posted.

Servo Centering

Servo arms easily move with your fingers until you place power to them. Once power is applied to a servo, they go to a ‘neutral’ position and hold there. It’s only in this position you want to attach the servo arm at the 90 degree angle to your wing, before you mount the servo. By hooking up the battery to the ESC and receiver (you don’t have to be bound to your transmitter for this nor have the motor hooked up) and the servos to the receiver, you just built a servo test circuit. Apply power, let the servos neutralize, then screw your servo horn in. After that you can remove power.

Push-rod Installation

Now that you’ve installed the servos with tape, apply power to the circuit (motor connection and binding not necessary). The servos will be in their neutral position. Slide the bend into the control horn on your elevon, then guide the wire through your quick connect on the servo horn. Lay the elevon flat, lined up with your wing, then slowly tighten the screw. This makes it so that when the servo horn is in the neutral position, so is your elevon. This is why we use adjustable connectors on the servo horns, instead of trying to cut wire to the exact length and bend on both sides.

Binding

Binding is the process of matching the unique Ids of your transmitter and receiver so they only talk to each other. In 2.4 GHz systems, this is what allows you to fly next to someone else without having to worry about your transmitter taking control of their aircraft. (People tend to dislike this, which is always a risk when using 72 MHz FM crystals). To bind the transmitter and receiver, shut off your transmitter, and place a bind plug into the bind plug socket on your receiver. This makes the receiver enter bind mode when powered up, which you can see by the rapid blinking light on the receiver. Then, turn your transmitter on (with throttle stick down) in bind mode. On our DX6i, that means turning the transmitter on while holding the trainer switch, then letting go. This tells our transmitter to search for his soul mate, and when the two meet, lights go from flashing to steady. Once bound, you can test the servo movements to make sure connections are working, then disconnect your battery and remove the bind plug. You only need to bind once.

Servo Directions

Assuming you’re bound and electronics are hooked up, you should test the servo movements so the elevons rotate in the proper direction. No motor hookup is required. Pushing down on the right stick will cause both elevons to move upward. Pulling up on the stick, will cause (in opposite fashion of down-stick) the elevons to move downward. Pulling right on the stick will cause the right elevon to move up, and the left elevon to move down. Pulling left on the stick will cause the left elevon to move up, and the right elevon to move down. These are important pre-flight checks before you fly, I should know, one of my recent builds crashed within seconds because I was up all night building it and didn’t do a proper pre-flight check on servo direction. If your servos areNOT moving in the directions listed here, you may need to reverse the connections on your transmitter, or the servo cables on the receiver until you reach the desired result.

Throttle Range

When you first use an electronic speed control with a transmitter, you often need to set the throttle range, so the ESC is programmed to know how far your throttle stick on the transmitter moves. Some ESCs auto-detect this, consult your ESC’s documentation. Our ESC (and this applies to most ESCs for throttle programming) is calibrated by turning your transmitter on first, and put your throttle stick all the way up. Then plug in your battery, and you’ll hear warning beeps, in this case two. Then, move the stick all the way down and the ESC will respond with two more beeps, and then the flight music once it’s armed and ready to go. Like binding, you should not have to repeat this step unless you swap to a different transmitter.

Motor hookup

Although you mount the propeller so that any wording faces away from the aircraft, you can still have the motor going in the wrong direction. Hook up the motor to theESC and give a little throttle to your craft, you won’t need much. When in the wrong direction, you will feel NO air flow behind the prop and over your craft, you’ll instead feel air in front of the prop. If this is the case, shut down your throttle and reverse any two cables on the motor. (I like to reverse red and black, gives me that rebellious feeling). Then try the motor again, you should have air flowing over the wing instead of away from it.

Center of Gravity

After you’ve mounted all the hard electronics and foam on your plane, it’s time to check your center of gravity. You’ll notice on our flyer the marks 1/3 from the front of our wing where the angle ends. This is the center of gravity, or pretty darn close. Now, we haven’t secured the ESC yet, and you can tell by an initial balancing that our flyer is nose heavy (due to the motor and prop). So we’ll definitely move our ESC back as much as possible and temporarily mount it. It’s no longer as top heavy. I generally fly just a little forward of the planned CG, but the ESC alone is clearly not going to cut it. This is why we mount our battery last. It acts as the final trim of our balancing. So you can see if the battery is placed near the receiver, it comes very close to being balanced. Moving it forward a tad, you can see we’re now nose heavy again. Placing it right above the receiver balances our version, so this means we’ll mount the battery in that same position on the underside of the craft.

Too far back, tail heavy, too far forward, and it’s nose heavy. If you must err on one side or the other, err on nose heaviness. As Chameleon says, a nose heavy plane will fly with difficulty…a tail heavy plane will fly ONCE. We then place a strip of velcro on the bottom of the plane along the fuseleage. This let’s us adjust the center of gravity if we decide to try a lighter or heavier battery in the future. In that case, simply move the battery mounting back or forth.

Stencils

One of the things to consider as you start cutting out more of these plans is that there are some shortcuts you can take to ease the process. For example, I’ve created stencils of the plans on Elmer’s Poster Board, which works out well. When cutting a new flyer, I place the stencils on the foam, trace, then cut. No more measuring required. I’ve also cut out the stencil so that the part of the foam I would normally dig out after building up the fuselage (see first video) can be cut away beforehand, which builds up the recession for the electronics without having to pry out foam pieces afterward.

Firewall Mounting

I mentioned shortcuts… some you can take, some you can’t. This is what happens when you don’t mount the firewall well enough. I did not, and now my combat plane has unsightly dangling bits. Given that our firewall is attaching to such a large piece of foam, you must ensure the firewall is well epoxied, sanding the nose flat beforehand. You should also make sure the four screw-holes are bigger than the screws you’re using, since you’re filling the screw-holes with epoxy before your motor mounting, to give the screws something to bite. What I failed to do here was make sure the epoxy filled the screw-holes in well enough. This left too little for the screws to bite and the firewall popped right off for these reasons. So drill wide, fill well, and much like the Spice Melange, remember that the epoxy must flow. (Nerdy DUNE reference, my bad).

Prop Size and Watt-Meters.

We’ve used 9×5 and 8×4 props with this configuration of a specific motor, ESC and battery. You should always be careful when building your own configurations that you’re not going to pull too many amps through your circuit. A watt meter is an essential tool for making sure you don’t release the magic smoke from your electronics. Given our ESC can handle up to 30 amps, our motor has a max of 18 amps and our 1000 mAh 20 C battery can give 20 amps, we want to make sure we don’t pull more than 18 amps through the circuit because our motor is the limiting factor here. You can handle at most 18.5 if you’re moving servos at the same time, as you can see they take a few milliamps. When testing this, make sure you use a fully charged battery. You can see my burst is about 16 amps, and generally running around 13 to 14 amps, so we’re pretty safe with a 2 cell Li-Po battery. Replacing that with a 3 cell Li-Po, our motor spins faster without having to move the throttle all the way up, we hit 18 amps before the throttle was at 100%. You don’t want to go any higher, otherwise you’ll put out more amps than the motor can handle. How do you rectify this? Use a smaller prop, either in size or pitch, and retest. Get comfy with this idea, as bench tests like this save you heartache in the air. Unless you’re shooting for exploding electronics or flaming foam while flying, then by all means, go forth my son and ROCK… just don’t blame me.

What’s next?

That does it for this second article in our COMBAT! Series. Just a few hints, tips and ideas. Hopefully the next article and video will hopefully have some combat flying. I’ve got video of these things flying in the air, but I’ve little if anything of them hitting each other. So, wish us luck, hope we don’t suck, and maybe in the third video we’ll actually have some mid-air crashes.

Note: HoverAndSmile.com is no more.  The content has been migrated into krystof.io.

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