Wednesday, December 10, 2014

How to recognize toy grade RC aircraft

Saving you agony

I previously wrote about toy grade vs. hobby grade RC aircraft, and talked about the problems I've had with toy grade aircraft with failure rates, customer support and the like. However, that doesn't really help if you can't tell the difference. So here, I'm going to tell you how I recognize toy grade vs. hobby grade RC aircraft.

One point I want to make now is that all RC aircraft - at least, the ones I buy - are toys. They don't do real work, like drones. I don't make money off the hobby, other than a few pennies from ads on the blog. I buy them to have fun flying them. I don't enjoy toy grade quads for a number of reasons, but that doesn't mean there isn't a place for them.

To me, the real distinction between toy grade and hobby grade is in the product strategy. Is the point a single sale, and once you've bought the thing you're on your own? Or is it to build a relationship with you, so they can continue selling you things for years to come? If it's the former, you can expect the aircraft to have problems sooner rather than later, and very little help from the manufacturer. If the latter, they hope it'll last long enough to sell you supplies, and make you think buying replacements and upgrades is a good investment. All of the differences noted below can be explained in terms of which strategy the company is using.

So, with that in mind, let's start looking at things you can check on.

The Box

Or the web page, which now serves this function.

One thing you can check on easily in the store is the box. A toy is more about looks than performance or durability, so does the box have a clear plastic cutout to show off the aircraft? Does it feature images of people having fun with the aircraft? If so, then the packaging or web site was designed to make a quick sale, so expect it to be a toy.

Hobby grade aircraft will have information about performance featured just behind the aircraft in importance. After your first aircraft, you're probably looking for some kind of upgrade, so you need to know what kind of performance an aircraft will give you. If these things are featured or easy to find, they're hoping to sell to a more experienced pilot, which is part of a the long-term, hobby grade strategy.

The Name

You might be wondering what name could have to do with this. But names are chosen by the marketing department to communicate something to the consumer in hopes that it will help sell the aircraft.

Hobby grade aircraft tend to have names related to an important specification. So a 450 something could indicate that this is a 450 size aircraft, for some measure of size. This is moving the specification information up in importance, again catering to an experienced pilot as part of the hobby grade strategy.

A toy would have a name suggestive of fun or experimentation or excitement, to help with that quick sale. A name with little or no relationship to the model or other models in the line is a minor hint that it's a toy grade aircraft, as that does make the name more like a hobby-grade aircraft name without the benefits of using such.

Most likely is a name with no meaning at all. With no meaning, there's no information to help you choose.

Replaceable battery

One easy test for toy vs. hobby grade is whether or not you can replace the battery. The LiPo's used in these things have a relatively short lifespan. Especially when used with an off-the-shelf USB charger, which can charge them at a high enough rate to damage them.

If the manufacturer expect the battery to outlast the aircraft, the aircraft is clearly a toy. Selling batteries to make extra money is clearly a long-range plan.

Spare parts

Spare parts is another major clue. If the manufacturer expects you to throw it away rather than repair it, then they aren't planning to make money from you beyond the first sale, so it's a toy. If they hope you'll enjoy the thing enough to want to spend money repairing - or upgrading - it, then they're in it for the long haul.

The existence of spare parts also means that there are more likely to be hop-ups from third parties, that you can use to improve the performance, looks, or durability of the aircraft. Having the option of buying these instead of building them from scratch is a good thing.

Similarly, lack of spare parts is an indication that they don't expect you to work on the aircraft, so doing so will be more painful.

But the existence of spare parts isn't a guarantee that you've got a hobby grade aircraft. Some toy grade aircraft have become so popular with hobby pilots that the demand for spare parts became to large to ignore. So the manufacturer started selling spare parts after the fact. This will solve some of the problems mentioned here, but not all of them.

Features

These days, RC aircraft flight controllers have lots of advanced features. Things like auto-leveling and pre-programmed maneuvers are fairly common. Naturally, they are used to further the goals of the company. Since the two classes of product have radically different goals, these are good things to use to differentiate between the two.

Toy grade models tend to come with features that make doing cool things easy, because that sells toys. Things like reversing the controls when you invert the aircraft (a practice abandoned by hobby pilots decades ago), or some kind of automated stunt are common.

Hobby grade models use those advanced features to make the model as easy to fly as the toys. However, they will also have an expert mode that lets you do those cool things. Doing them is harder because you actually have to be able to fly them, making them a less attractive toy. But working with the expert flight mode will help you move on to more advanced maneuvers and hence more capable aircraft, which furthers the companies long-range goal.

Safety

This may just be the grumblings of an old man, but the toy grade systems just don't seem to take safety considerations into their designs. While many of these design decisions aren't necessarily unsafe, they either encourage bad habits or fail to encourage good ones.

For instance, I've never seen what I'd otherwise consider a toy grade controller that has a throttle hold feature. This locks the throttle against accidentally spinning up the aircraft propellers while you are working on them. For the very small aircraft that toy companies use to enter the market, this isn't much of an issue, as a blade strike will at most sting. On the hobby grade side, there is at least one recorded instance of someone being killed by the blade of a large hobby grade aircraft.

Similarly, hobby grade radio systems are designed so you turn on the transmitter first. This design is intentional, as it means the receiver won't start accepting controls from some other radio source, which could cause unexpected and uncontrolled flight. Probably not an issue with digital radios, but still a good habit to have. Toy grade systems either don't care, or require you to turn on the aircraft first, which is a dangerous habit to get into.

You should also ask what the aircraft does when things don't work right. What if the radio quits working, or it runs out of power when it's 300 feet in the air? A hobby grade aircraft should have documented behavior in those cases, or possibly the ability to control what it does with a failsafe feature in the receiver. Since mentioning such failures would scare away potential buyers, not doing so is a sign you have a toy grade aircraft in your hands.

This also goes back to batteries. Hobby grade aircraft should come with a warning about proper care of LiPo batteries, pointing out the potential for them to explode. But that warning will again scare away potential buyers, so is likely to be omitted from toy grade aircraft.

Product line

Now we're getting to the really vague. But his gets to the heart of the question about what the companies strategy is.

Is this a stand-alone aircraft with little or no relation to other aircraft from the company? If so, then they probably don't expect to see you after the sale, and it's likely a toy.

On the other hand, does it share parts with other aircraft, and is clearly part of a line that will let - or even encourage - you to buy better aircraft from them as your skills improve? If so, then it's likely a hobby grade or better aircraft.

Checking these things requires looking at more than one model, but if you're thinking about getting into the hobby instead of just buying a toy, you'll want to do that anyway.

Controllers (aka transmitters)

Hobby grade aircraft tend to come both with and without controllers, and the manufacturer will provide a list of their controllers they recommend to fly the aircraft. Their better controllers will be able to remember settings for multiple aircraft, allowing you to fly multiple aircraft with one controller.

A good controller - which will have gimbals with smoother movement and higher resolution, as well as the ability to set a wide variety of things that affect the flight characteristics of aircraft - can easily cost an order of magnitude more than a cheap aircraft, and makes more than that much difference in flight! So selling you a good controller is one way of keeping you as a long time customer. You'll prefer buying aircraft you can fly with that controller to buying another expensive controller or using a cheap one with someone else's aircraft.

Toy grade aircraft tend to be available only with a controller (but again demand can change that), and the transmitter may or may not work with other aircraft from that company - you'll have to try it and see. The goal is to make as many sales with as much profit as possible, not to encourage you to buy lots of things over years.

Nonfunctional buttons

Related to this and the emphasis on quick sales are controllers with non-functional buttons or bolts. They get added to make the controllers look more like hobby grade controllers, even though they do nothing - because looks are an important part of the fun of a toy. Or possibly the manufacturer recycled a controller from another aircraft, and the button may actually be functional, but have no function with the aircraft you're looking at.

Hobby grade aircraft may come with controllers with buttons that don't do anything with the aircraft that they come with, but the controller should have its own documentation, saying what they actually do. This makes the controller more useful on other aircraft, which they hope you'll buy. The toy grade company doesn't plan on them being used with other aircraft, so won't document what the button does much beyond "no function". And even the cheapest hobby grade aircraft don't have the fake bolt heads I've seen on toy grade controllers.

Receivers

Once you get past the very smallest aircraft, you'll start seeing receivers as a replacement part on hobby grade aircraft. And you'll see them used on other aircraft. In fact, you may well see "receiver-ready" or "plug-n-play" or similar designations on hobby grade aircraft. The manufacturer expects you to provide a receiver that will work with your controller, and should tell you what type of wiring you'll need to connect things to it.

This one really requires checking out multiple models from the company. I particularly like this one, as toy companies I'm familiar with don't produce aircraft in the sizes where this is at all common. I've never seen anything smaller than a 200 size helicopter that did this, and not even all the hobby grade aircraft in this size do it. The largest helicopter I consider toy grade I could find was a 250 size helicopter. These are considered micro or mini helicopters by hobby grade standards, but are called "large" in the toy grade world.

Final comments

These are just the things I watch for - and try to avoid. I don't believe any of them are conclusive by themselves, but will check on multiple things. And knowledgeable people I respect disagree about this list, and the conclusions I've drawn from it. But getting a lot of these on either side of the line is a good indication about which side a particular company or aircraft will land on.

Unfortunately, you can't judge an aircraft by the company that made it. The hobby and toy companies are now clearly in competition, and adopting practices from each other. Sometimes this makes a toy grade aircraft seem more like a hobby grade aircraft, and sometimes it does the reverse. But it also causes companies to produce aircraft that aren't of the same grade as their previous products.

Bottom line: Decide which of the things above you really care about. If you've decided a company tends to produce toy grade aircraft, decide how important build quality and customer support will be for a particular purchase. Then buy something that fits your goals. I hope I've provided some clues to help you do so in a more informed manner.

Sunday, October 26, 2014

SLH 6047 Scorpion review


The Why

Every time I buy a toy grade 'copter, I feel like I need to justify it. In this case, I was adding an RF module to my Devo 10 running deviationTx, and wanted something cheap to test it with, rather than risking the more expensive models I was planning on using this for.

The SLH 6047 used the new module, and wasn't just another toy quad. Or even a helicopter. So it was something new to try. Filling two purposes and having a good review from Flyin' Ryan1 made it an easy choice.

The What

What's unusual about the Scorpion is obvious when you look at it:

IMG_20141026_104136.jpg

It's got six engines on three booms, with a coax pair on each boom. The lower engine is inverted.

Some folks call this a tricopter, because it's got three booms. Others call it a hexacopter, because it's got six engines. I don't feel either is right, because it doesn't fly like a tricopter or a hexacopter, but will go with hexa because it could be called a hexarotor.

The Review

So, let's look at the thing.

First impressions.

To me, the pictures make this look a lot bigger than it really is. It's a small 'copter, being barely bigger than the Nano QX:

IMG_20141026_104220.jpg

Part of what makes it look large is that it also looks solid. This, unlike the size, is not an illusion. This thing is rock solid, and has a feeling and weight to match.
It's been through numerous crashes at speed and the only thing that's broken is a propeller. Unfortunately, it was the same orange one that was broken when it arrived2, so I've had to use the black spare, which is what's in the pictures.

In investigating replacement propellers, you can use standard multirotor propellers for the top ones. However, the bottom ones are pusher props, which are much harder to find in that size. Something to keep in mind if you plan on flying one a lot.

The flying

Coax multirotors tend to be stable but with poor efficiency. They have lots of lift for their size, which the scorpion needs because of its weight.

What that translates to is trouble overcoming its own inertia. It seems slow to respond to the sticks, and tends to keep going once you get it moving. The controller it comes with makes this worse, but I want to talk about that at length, so see further down.

This thing has been around for nearly two years. The technology in these things is changing fast enough that that's several generations old, and it shows. It doesn't even fly well compared to better toy quads of that era.

In summary, I can only recommend this if you want something other than yet another small quad.

The controller

It's been quite a while since I've looked at a toy RTF controller, and this one is much nicer than those. SLH gets credit for making it configurable enough to fly lots of different aircraft. All four channels can be reversed. You can also configure whether or not it beeps at you. Nice.

Toy controller problems

That said, it's still very much a toy RTF controller. While it has two rates, you can't set what they are. Nor can you alter the control curves in any other way. The fact that this aircraft is slow to respond is made worse because the controller seems to have a dead band near the center of the cyclic controls. Could be a quality issue with the one I got, or it could be designed that way so the toy-grade gimbals have a properly neutral center stick.

A hobby grade controller

Since the point of buying this was to test a new RF module in my hobby-grade controller, flying it with that was one of the first things I did.
This immediately brought a lot of new features to the table. A real throttle hold switch, to help reduce damage to the 'copter and bystanders during crashes. The dual rates are a switch, not a button, so it's possible to tell by feel if it's in low rate mode. Ditto for the flip functionality. Of course, all three have inverse video icons on the screen which are much easier to see than the dual rate symbols on the RTF controller. There is no indication that flips are enabled on the RTF controller, but it seems to time out quickly. And the RTF controller has no throttle hold, so that doesn't need an indicator.

More importantly, the dead band issue is gone. Getting rid of that makes the thing fly much better. Even better, I can apply some expo to the high rate curve, which makes flying it a lot saner. I feel that this justifies my avoiding 'copters that I can't fly with a hobby-grade controller.

The rant

It's not obvious if all you use is toy grade RTF controllers, but the controller is the important part of an RC aircraft system. It is the connection with your aircraft. So it having problems will also mean you will have problems with your aircraft . Similarly, if the controller is improved, say with better gimbals, or faster response, or whatever, then you'll have improved control of your aircraft, and an improved flying experience.

On the other side, getting the system set up properly is a critical part of an enjoyable flight. Large parts of the setup of a modern 'copter happen on the controller. Much of the functionality showing up on flight control boards can be done in the controller with a good enough controller. So again, a better controller means a better flight experience.

In summary, if you're just flying the toy-grade RTF controllers, you're cheating yourself out of a better rc experience.

  1. If you fly small 'copters and aren't familiar with his reviews, you should check him out. 
  2. Fortunately, it was fullfilled by Amazon. They couldn't send a replacement prop, but gave me $10 credit instead. 

Thursday, October 16, 2014

Why PayPal sucks

Introduction

Every so often I run into someone who uses PayPal on a regular basis, and has never had a problem working with it. While I believe they are entitled to their opinions, and have no problems with them choosing to use PayPal, I think they ought to have all the facts. So I've written up my experience and what I've discovered about the company. But one person's experiences may not be indicative, so you can read other people's problems with PayPal.

Understanding PayPal

What PayPal is - and isn't

PayPal's early attraction to the consumer is that they don't give your credit card info to merchants, which provides an extra level of security. That used to be unique, and them being first has made them very popular. These days Google, Apple and Amazon all have similar services, or have at least announced them. There are also a slew of others, possibly even Microsoft, but none of them have made an impression on me. All of these services are free to you for making purchases. Which means that, as with any free web service, you are not the customer, you are the product. In this case, it's easy to tell who the customer is - it's the merchant you're buying from, who is paying for an easy way to get customer payments.
One difference between PayPal and the other three is that the other three all have store fronts of their own. PayPal doesn't. That means that you are, at least when buying from their store front, a customer of those other three. So they will treat you like a customer. You can also see how the vendors are customers there, because the vendors pay a premium in order to have products show up in those three stores. It's worth pointing out that, unlike those four, when you make a purchase using a credit card, you are a customer of the bank. The merchant is a customer of the credit card company, not the bank.
Another difference between PayPal and the other three is that PayPal wants to hang on to money for you, which lets you spend it from your account instead of your credit card, sort of like a checking account at a bank.
It's important to know that, even though PayPal acts like a bank issuing a debit card from your perspective, it is not a bank. It isn't bound by the laws covering banks or debit cards, and you get none of the legal protection you'd have with a real debit card.

How PayPal makes money

Looking at how all these entities make money helps explain their behavior. Apple, Google and Amazon make money primarily by selling you things from their storefront, and have moved into the payment processing market to get a slice of the money from other sales as well. Banks make money by charging you interest on money you borrow, or by making interest on the money they hold for you for a debit card, and also by charging a variety of fees. PayPal makes money on payment processing fees, and by making interest any money they convince you to let them hold.

PayPal's behavior

So let's look at how PayPal has treated its users.

General behavior

Another difference between PayPal and the other three payment processing companies: PayPal has lost a series of class action lawsuits brought by its users for figuratively stealing their money. PayPal has a habit of doing everything they legally can to keep earning interest on money that people have trusted them with. Making it hard to contact them, freezing account withdrawals (but not deposits!) for suspicious behavior, then having hard to find and even harder to meet requirements to unfreeze them, and so on. That's what's caused those lawsuits.
While PayPal has improved things a bit (you can now call their mis-named customer service department), this is mostly because they have been forced to as part of various settlements, not because of a change of attitude. The lawsuits didn't stop until they changed their terms of service to say you could not sue them about these things.

My experiences

I opened a PayPal account over a decade ago, with an email address I still use. They doubled billed me for a purchase. I eventually found an email address (there was no phone number to be found on their web site at the time, one of the things the lawsuits forced them to change), and asked about this, and was told "Just have your bank reverse the charge." I did. PayPal ran the extra charge again. I reversed the charged again, and PayPal did a bank transfer to get the money. This happened another time or two - I forget the details, because it's been over a decade. Eventually, I got my money back, but they froze the account for "suspicious activity" - which state it's still in. They also took the money back from the eBay vendor, claiming I said the merchandise was never delivered, making it look like I ripped off the merchant, when it was in fact PayPal that had done so.
That old account still exists, and is permanently locked. This means that, should I make a purchase with PayPal and forget - or not have the option because my account with the vendor uses it - to use an alternate email address, I risk refunds winding up in that locked account. It's happened, but not reliably.
So having recently started buying from (only when there is no reasonable alternative) merchants that only accept PayPal, I've had the dubious pleasure of using PayPal's "customer service". While I can now reliably get someone on the phone to talk to, they are just as reliably useless. Fortunately, there is usually a supervisor available, who is only mostly useless. If you've got a representative from your bank on the line to talk to them, you can actually get them to give you your money back. But nothing short of that has ever gotten PayPal to release money they owed me once it's held.
Maybe things would be better if I had a PayPal account, and let them make interest from my money. But this seems silly when I can get a free credit card with no fees, no interest charges for 30 days - much longer than PayPal will extend me any credit, I get a small percentage of my purchases back as a reward, gives me the legal protection of using a bank issued credit card, and comes from a company that treats me like a customer instead of a product.

Summary

Yes, merchants that use PayPal - or sell on eBay, which is another rant - are usually cheaper than Amazon or those that take real credit cards. But understand that there is a reason for that: customers that make payments from a PayPal account have given up the legal protections they would have from using a bank credit card, which is how PayPal can charge less than the credit card companies.
This doesn't matter so long as things go fine, but the real measure of a company is in how they behave when customers are unhappy. By my experience, and that of many others, PayPal is doesn't measure up.

Friday, October 3, 2014

Introduction to Open Source Transmitter Firmware

Open source

What is open source

If you're not familiar with it, open source software (or books, movies, hardware, etc.) is software for which the source is freely available, and redistribution is allowed. The Open Source Initiative web site has a detailed definition and discussion.

In practices, this means that anyone can take the source, modify it to better meet their needs, and contribute those changes back to the project, or create a new project based on their changes. The latter is known as forking the project, and the new project is a fork of the old one. Because the source is visible to the users, the engineering processes are also often visible to the users - you can see the problem reports, changes to the source, etc.

The opposite of open source software is closed source, or proprietary, software. The source is not available, and the engineering processes are usually not visible to the end users.

Why you would use open source firmware

The second paragraph above contains the primary reason you'd want to use open source firmware in a transmitter: you can modify it to better meet your needs.

For instance, someone noticed that the popular Devo 7E transmitter - which the open source firmware deviationTx runs on - had unused control lines on the micro-controller it used. So they added two switches to the hardware, and support for the two switches to the software. That wouldn't have been possible if the source hadn't been available.

To compare it to models, open source firmware is like having kit, whereas proprietary source is like the all-in-one electronics boards used in micro and nano-sized aircraft.

So suppose you added a spotlight with servos to point it to your scale aircraft. If you can't control the servos, they have no purpose. With a kit, you can just plug the servos into spare channels on your receiver. If the receiver doesn't have enough channels, you can replace it with one with more channels. If you have all-in-one electronics, you may not know if you have enough channels, and even if you do, there may not be any way to access them. On the transmitter side, proprietary firmware should let you tie those channels to controls on the transmitter. Open source firmware lets you program a switch to move those channels in a search pattern.

Like the kit, open source firmware doesn't mean anything is possible. The kit may not have space for a receiver with enough channels, or the model may not be able to lift what you want to add. Your controller may not have enough memory for the modifications you want to make, or it may not be fast enough to do what you want as well as keeping up the channel communications.

Why you would trust open source firmware

If you're not familiar with open source software, you may now by wondering why you would trust your expensive model to software written by a bunch of amateur programmers in their spare time. The answer is - that's not the case.

Many - if not most - of the developers working on open source software are professional software developers. Or possibly students. Working on open source projects is not looked down on by most companies, and is an accepted way to develop new skills or learn about new software tools. In some companies - most notably if the engineers still have some say in the screening process, or the company is using open source software - contributions to open source software are a requirement.

Which brings up the spare time question. Open source is used in many commercial products - DVD players, DVR's, printers, etc. Apple's operating systems (but not the user interface code) are based on open source software, and many components are still open source. Microsoft uses open source in their operating systems. The Android phone and tablet operating systems are open source, which is why forks like Amazon Fire can be created. And there are at least two commercial transmitters based on open source firmware: the Turnigy 9XR and 9XR Pro, and the FrSky Taranis.

Professional developers work on these products as their job. In some cases, the people contributing to them do so as their job, because their employer uses that software in some capacity.

It may be hard to believe, but we enjoy programming. I'm sure the people who work for large hobby companies don't stop building and flying models just because they are now getting paid to do that. Personally, I'd rather use software written by someone was doing it as a labor of love than someone who was just trying to earn a paycheck. In at least one study, open source was shown to have better quality than closed source.

The fact that the open source projects have publicly readable problem reports means I can check them for issues with my model, and possible fixes - and if there's a patch for the software, I can apply it to my copy! This just isn't possible with proprietary software.

And finally, the authors of the open source firmware all trust all their aircraft with it.

The firmware

Versions

That anyone can fork an open source project can cause a problem in that it makes lots of forks possible.

One popular open source firmware family - I'm going to call it the TH9X family, because it was initially written for the FlySky TH9X transmitter - has more forks than I can count. Many of them exist because the author wanted to experiment with radically different interfaces, but most of the popular ones - based on activity in their forums and source repositories - are very similar.

On the other hand, the deviationTx software is also very popular, but there aren't a lot of forks of it, and most of them have actually been incorporated into the main distribution.

I wrote an overview of the choices a while back.

Hardware

The choices for hardware range for cheap clones of the original FlySky TH9X to relatively high end transmitters like the Walkera Devo 12S. I also wrote an overview of those. The only real change is the release of the Turnigy 9XR Pro. That has gotten mediocre reviews, whereas the Taranis has generally good reviews since this was published. The Taranis is generally considered the better buy for the price - at least once you factor in the cost of buying the things the Taranis comes with that the 9XR Pro doesn't.

Using it

The popular open source firmware choices have similar interfaces - and it's not at all like what you find on proprietary transmitters.

Closed source behavior

Every computerized closed source transmitter gave you roughly the same set of controls. The first four to six channels have their output from the specific controls, and that can't be changed. Beyond that, they are from specific controls, but you can move them around.

There are then specific controls for manipulating those channels in ways that depend on the aircraft type. You enable dual rates and/or expo on some of the channels, usually enabled by one of a few switches. You can set a throttle curve, and possibly have a throttle hold or throttle cut. On helicopters, you can set up pitch curves selected by flight mode. And so on.

You also usually get some small number of mixes which let you modify an output channel based on a control other than the primary one.

The goal is to make setting up the manufacturers receivers easy, and it generally does that. Which is why all of the proprietary transmitters I've seen do things this way. If you're aware of one that is radically different, please tell us about it in the comments!

Open source

The popular open source choices - most notably deviationTx, OpenTx (on the Taranis) and the TH9X variant on the Turnigy 9XR - all have similar interfaces.

The first difference with closed source comes from the fact that, while the radio protocols may be radically different, the actual RF module used in proprietary radios may well be the same, and the difference is in the way the bits are sent. So open source firmware may well let you choose a protocol. You might also be able to add an RF module, and the firmware will change modules depending on the protocol selection.

Second, the number of channels on a digital radio is just a matter of software, as each channel is a slot in the digital packet the transmitter sends to the receiver. Since the open source authors aren't making money selling the software, you can configure the number of channels for each model. The limits depend on the speed of the CPU and the protocol, not keeping the low-end models from taking sales from more expensive ones.

Third, this software typically either doesn't have mixes, or has many of them, depending on how you count.

Each channel is - or can be, depending on the firmware - a mix. Or several mixes. Each mix can use any input control (pretty much required to support multiple protocols), can be enabled by any switch, or none, can have it's own curve - including fixed values that ignore the input - and can be combined with the previous mixes in pretty much any way you'd like.

There are also virtual channels that aren't associated with a transmitter output. They can be used for creating values to be used in the output channels.

Channels can also be used as switches, with their value determining the state of the switch. Some versions layer in virtual switches, which can test channel values and use the value of other switches in determining their state. All of these can be used to enable or disable mixes.

This is by no means an exhaustive list of the features available in open source firmware - it's just a list of the features that are common among the popular versions.

Pluses

The benefit of this model for transmitter software is that the firmware is very flexible. Some examples follow.

Since you can use a virtual switch for the throttle hold switch, you can create a sticky switch for the throttle hold, that doesn't turn off unless the throttle output is off. This means you can't accidentally spin the prop when you turn off the throttle hold.

The Blade 200SRX has a panic switch that enables auto-level and disables the cyclic controls. This can be done on the transmitter with open source firmware - at least if your aircraft has auto-level. Set the channel that controls auto-level to a value that turns it on, and use the same switch to enable the last mix for each cyclic channel to set the output value to the level mode. Or - since each output channel has a safety switch and safe value, not just the throttle - use that switch for the safety switch and set the appropriate safe value.

Minuses

The downside to all this is that there's no guidance. There are no settings for elevons, you have to know now to set up the mixes. You have to know which channel controls the pitch, and set the curve on it, not via a pitch curve control.

The popular firmware is solving this in a variety of ways. Some have desktop software that looks more like the proprietary controls, and you can use it to create a model to download to your transmitter. Others have a traditional mode that looks like the proprietary firmware, and you have to enable advanced mode to get the full power of the firmware. These are still very much works in progress.

Legal issues

Since you're working with a radio transmitter, your government probably has some things to say about what you can and can't do.

Since the software doesn't change the RF behavior of the radio, but how the controls change the digital values in the RF signal, just changing the software shouldn't be a problem. But that could depend on whether the licensing is for the transmitter as a whole, or for the transmitter module that the transmitter is using.

Changing the protocol might also be a problem, depending on the country you're in.

Modifications that alter the RF behavior - adding a module, or changing the power output levels - almost certainly invalidate the license the transmitter was sold under.

In the US, you'll be ok so long as you keep the power under 1 watt on the 2.4GHz band and aren't planning on selling the thing, because that usage falls under the FCC Home-built transmitters clause.

Conclusion

Using open source firmware on your transmitter provides a lot of extra flexibility in how you control your aircraft, at the expense of making common but not simple tasks harder. It's not for everyone, but the only reason to avoid it if it's for you is that it might not be legal where you are.

Thursday, September 4, 2014

Hobby Grade vs. Toy Grade

Grading RC?

One of the things you notice in this hobby is the cost difference between traditional RC companies like Blade and Walkera and the companies that started out making toys and moved to remote control toys, like WLToys and SanHuan. The explanation for this is usually that the former are Hobby Grade and the latter are Toy Grade. I'm going to illustrate the difference.

Hobby grade

Over the years, I've bought 11 different blade 'copters (an MCX S300, MCX2, MCX Tandem, CX3 MD520N, MSR, MSRX, MQX, NanoQX, 350QX, 200QX, and a 200SRX). I've also purchased a Walkera Mini-CP and a Nine Eagles Solo Pro 126v2 Night Edition. One of the Blades, the Walkera and the Nine Eagles came with controllers.

In addition, I've purchased a DX6i and DX5e controllers to use with the others. I've also purchased 2 Walkera controllers.

Quality control

Every one of the aircraft flew out of the box. Maybe not well, and maybe not quite as designed, but they were at least flyable. Only one of them was in any way broken. All of the controllers worked fine for flying out of the box, though one of the Walkera controllers had a broken USB port causing me to exchange it.

The MSRX had a nasty design issue in that anything more than a little rudder input tended to cause it to start flying off to one side or the other. This made it a PITA to fly, so I sold it. But it was working as designed.

The first 200SRX flew fine - except that it didn't self-level in intermediate mode. I exchanged it, so it gets counted once.

Customer support

Any problems that I've had with Blade products after the fact - mostly meaning things breaking long after I bought them, or replacement parts that turned out to be broken in some way - were generally fixed with a call to Horizon, and a replacement was in the mail to me that day or the next. Lately, they aren't doing as well - they can't seem to decide how their new products are supposed to work.

I haven't had a chance to check Walkera or Nine Eagles customer support, but reports are they aren't as good as Blade.

Quality

All of them have been relatively durable. Further, when they do break, replacement parts are readily available, and repair is usually relatively simple. They are designed to be repaired when broken.

Toy grade

My experience with WLToys isn't quite so extensive. You'll see why shortly. But I've bought 6 of those: (two V911s, two V939s, a V959 and a V915). I purchased a second V911 and V939 to use for spare parts. All but one of these came with a controller.

Quality control

Of those, four were broken in ways that made them unflyable when they arrived. Three of the broken ones had broken controllers: one didn't power on, one didn't transmit, and one suffered from intermittent power loss. Flying with the last one just isn't an option. One 'copter didn't power on and one copter was the wrong version so I didn't have batteries (not the manufacturers fault).

The V915 was the worst case: it came with a controller with an intermittent power loss, and a broken LED on the helicopter. The latter doesn't make it unflyable, but it's still not working properly.

Customer service

The companies that sell these - at least with the price difference pointed out earlier - have customer service on the other side of the Pacific, if not shipping from there. While I've written about these experiences at length, the short version is that it usually takes days to sort things out, and involves at least one exchange to clarify things for someone who speaks English as a second language.

Quality

The 'copters themselves seem to be about as robust as the hobby grade ones. The difference is, once you've broken them, repairing them can be a lot harder. Parts may not be available, and doing the repair is probably a lot more painful - because these are designed to be broken and thrown away. Some are cheap enough that that's not unreasonable, but that's not the case with all of them.

Controllers

The controller is very important, though until you've flown with a reasonable hobby-grade controller - even a relatively inexpensive one - you may not realize this.

Hobby grade

All of the controllers but the RTF Blade controller and the DX5e are computerized controllers. They have the ability to store multiple aircraft configurations and correct aircraft flight issues in the controller. They all have or can be configured to have a throttle hold, which is an important safety feature.

The best of the toy-grade controllers isn't as good as the worst of the hobby-grade controllers. The sticks just feel cheap, the gimbals aren't as smooth, and the controls don't feel as fine. The only hobby-grade controller that felt as bad as the toy-grade ones was the Walkera RTF controller, and installing $3 replacement sticks fixed that.

None of the toy-grade controllers are computerized. There is no throttle hold (though maybe the controller for a collective pitch helicopter would have one) and no way to configure one. There is no way to correct flight characteristics in the controller.

The toy-grade controllers copy the look of the computerized controllers. But that's all it is - the look. This is actually bad. For instance, while the newer ones have a standard five-way navigation button cluster, the five buttons do unrelated things, or are non-functional.

The worst feature of WLToys 'copters as a line is that the protocols seem to change willy-nilly. The six-axis version of the V959 - the V222 - uses a different protocol than the V959. The V912 - a six-axis helicopter - uses the same protocol as the V959. Except that the way they control the FPV camera on the devices is different. So while you can fly the V912 with the V959 controller, you can't control the camera, and other controls may well be mislabeled.

Finally, the worst feature of the controllers as a whole is that they tend to encourage bad habits. The lack of a throttle hold function is one issue. That some of them require turning on the aircraft and then the controller to rebind it every time is another.

Other than testing things, I won't fly with these controllers.

A breakdown

Most of my hobby-grade purchases have not included a controller, since I can use the same computerized controller for all of them. But most of the failures of toy-grade purchases have been the controller. So maybe things aren't so bad.

If you look at just the helicopter failures, it's 1 broken-but-flyable hobby grade helicopter out of 13 and one broken-but-flyable and one broken and unflyable helicopter out of six toy grade ones. That's over twice the failure rate.

And it's one broken-but-flyable hobby grade controller out of five and three broken and unflyable toy grade controllers out of six, or nearly three times the failure rate.

Summary

You get what you pay for.

I no longer buy toy-grade rc aircraft, except in unusual conditions. I must have a good reason to believe that I can fly it with a hobby-grade controller. If that isn't there, the sale won't happen. And there must be no comparable hobby-grade aircraft. So far, that means either a really nice scale body, or a multi-rotor configuration that's not generally available in small sizes.

Tuesday, August 5, 2014

Blade 200 SRX Review

The Blade 200 SRX

Blade finally came out with a helicopter featuring their SAFE technology. The results are impressive, though not as good as one could hope.

The Blade 200 SRX is a 200 size fixed pitch, single rotor helicopter. It features their six-axis (three gyros and three accelerometers) stabilization system known as SAFE. Like the 200 QX before it, it includes two flight modes with limited envelope and automatic self-leveling, and one flight mode with an unrestricted flight envelope and no self-leveling. In addition, it has added a Panic switch, that automatically switches to the most restricted flight envelope, self-levels and kills any cyclic input.

Early issues

I've had this one for longer than most before a review, because - well, there were issues.

Uncharacteristic support from Horizon Hobby

The first issue was with the first one I ordered. It would not self-level in intermediate mode. To verify this, I took the main rotor off, and spun it up on the floor.

In beginner mode, feed it some cyclic, let go of the stick, and the swash plate goes back to level.

In agility mode, feed it some cyclic, let go of the stick, and the swash plate stays put.

Intermediate mode behaved the same as agility mode. I put a number of batteries through it while investigating this, checking every possible source of problems. I eventually switched to a supported, non-programmable Spektrum transmitter (the DX5E) to make sure the problem wasn't in my transmitter.

I called Horizon Hobby about this, and they claimed it was behaving the way it was supposed to. I checked their announcement of the helicopter, the documentation, the introductory videos, and with other owners. They all say it should self-level in intermediate mode. Call HH support again, get the same story. Again.

So I returned it to the store and bought a second one. It behaved as expected.

Gain settings

I made a mistake with the second one. I checked the gain settings, and reset them all to the default values before flying it. This caused the heli to have a really, really nasty wobble with small cyclic inputs - just correcting for wind drift in a hover.

This problem pretty much vanished after I reset the various gains to the values that it came out of the box with. This took a few more batteries to get sorted, though.

So, a warning: don't reset the gain settings it comes with until after you've flown it!

Some tail drift

Finally, the tail had some wag and a little drift. Nothing really bad, but - well, I was expecting better. I upped the tail gain to correct the drift, and the wag got bad enough to make me nervous. I put that back, and have been flying that way. There's one more thing to try, but it's fun to fly as is, and I haven't felt like mucking with it more since.

Flight characteristics

As mentioned, it currently has a little bit of tail drift and wag. Neither is a problem in flight. The wag is mostly visual, and only when moving around. The drift is trivially corrected, and actually lower than some other heli's without the SAFE software.

The downside of SAFE is that I can't trim out the tail drift. Well, I can, but it will re-appear after I power cycle the heli, because the software compensates for the non-zero input.

The other nasty flight characteristic is that, compared to most 'copters, it just seems under powered. Half stick is just barely a hover when you're in ground effect. This sometimes causes issues when doing a fast descent, as it doesn't pull out of them nearly as quickly as I'm used to, leaving me bumping the ground a bit harder than I'd like. The most popular fix seems to be changing the pinion gear to get a higher head speed.

Other than that, it's a very pleasant flight. Earlier reviewers have called it "the quadcopter pilots helicopter." I don't know if I'd go that far. Where the self-level modes in a six-axis quad causes a fairly obvious slow down and stop when you zero the cyclics, this doesn't. It keeps most of it's forward (or sideways, or backwards) momentum after it levels. This is only a problem if you're expecting something different.

In agility mode, it won't self-level. But you do get enough flight envelope to do basic aerobatic maneuvers, just like the 200 QX. In theory, the Panic switch is supposed to give you enough confidence to stretch your limits here, but the lack of lift and not stopping after leveling sort of kills that for me.

Bottom line - this heli isn't as easy to fly as a coax or a quad. However, it's not nearly as hard to fly as most fixed pitch helis, and the agility mode makes it fly a lot like a collective pitch heli. It is a lot of fun to fly, and provides a better step between coax and collective pitch than was previously available.

Design issues

Outside of the flight characteristics, there are a couple of things Blade did that I think they could have done better.

Still no switch

Like it's homonumeric sibling, the 200 QX, there is no switch for the battery. Given that it has a typical helicopter canopy mount - tuck it in the front, and poles through grommets to hold the back in place - this makes it a real pain to plug in the battery and get it level with the canopy on before the flight control board initializes. I've finally given up on getting the canopy on before it initializes. I now plug in the battery, set it down, wait for it to initialize, then put the canopy on.

No LEDs

Well, almost none. The receiver and ESC both have an LED, but they don't do anything during flight.

In particular, there is no indication of which of the three flight modes you are in! This makes checking the setup on a programmable Tx nearly impossible. Most helicopters don't have such an indicator, but they also don't have as radical a change in behavior as stability to agility mode.

No LVC

Worse yet, lack of LEDs means there is no indication that your battery is running out. Other than, of course, the already under-powered heli losing power.

Sure, a good transmitter will have a timer, and will even let you pause the clock when the throttle is off, or possibly even change the clock rate with the amount of throttle. But still - that's just a guess. Changing batteries will change the time. A problem with the battery or charger could drastically change the time. And so on.

To add insult to injury, they put a telemetry-capable receiver in the helicopter. But it's use is restricted to reporting various gains and a vibration measurement. The absolute best battery voltage tool would be to use that telemetry to send battery information back to the transmitter. Just sending back the voltage allows for a voltage level warning in your hands instead of on the helicopter, which is a major improvement. Given other information, some really nice things are possible. But we get none of that.

Hence, my first modification to the helicopter: zip-tieing a lipo alarm to the tail boom. Still flies fine, but now I get an alarm when the battery voltage gets low. I've ordered a smaller alarm to dedicate to this.

Summary

While I seem to have spent a lot of text on problems, the biggest one to me is Horizon Hobby's support issues. The others are either minor, or trivial to fix, if not both. None would prevent me from recommending this as a second helicopter.

Being lied to by the support staff about this helicopter makes me nervous. Blade helicopters tend to be costly compared to some of the clones on the market, but Horizon support is usually outstanding, more than justifying the extra cost. If that's changed, it may be time to re-evaluate buying from them.

Saturday, July 19, 2014

200 QX Dialable Stagility Mode

The 200 QX

If you aren't familiar with the 200 QX, you might want to read my review of it.
The critical thing is that it, like other recent Blade quads, has both a stable mode and an agile mode. The stable mode (or modes) has a limited flight envelope, and will automatically return to level flight when there is no cyclic input. The agile mode has no limits on the flight envelope, but won't return to level.
This is a really nifty idea, as it lets the quad have a personality suitable for beginners, flying very much like a coax, as well as one suitable for advanced pilots, allowing acrobatics of various kinds, but requiring some skill to do. It's much better than the solution found on toys of having a flip button.

Stagility mode

The one downside of this is that - well, as you transition from one to the other, you'd really like to have the ability to do some acrobatics in stable mode, or have a open flight envelope that levels itself.
Some bright person figured they could get that if they could get the quad to switch from stable mode to agile mode automatically when it's given cyclic input. This is relatively straightforward - just mix the cyclic input into the channel that controls the mode appropriately.

The bad

While that approach works, there are two downsides to this:
  1. The behavior is fixed. There are a number of behaviors that might be desirable, and changing between them is generally not supported.
  2. There have been reports that the quad becomes unstable doing things this way.
While I set out to deal with #1, my solution means that, instead of getting odd values from a mix on the mode control channel, the quad only gets values it expects on that channel. I believe this should solve the stability issues, but a discussion with Horizon Hobby about it just resulted in "We still don't recommend that."

An automatic switch

If your transmitter runs deviationTx or similar, then you have the ability to use a virtual channel as a switch. If the value output on the channel is greater than 0, then the switch is on. Otherwise, it's off.
So, the first step is to get the deflection on the aileron channel. That's not hard. The mixer looks like so:
[mixer]
src=AIL
dest=Virt4
usetrim=0
curvetype=absval
points=0
That is, the source is the aileron input, and we want use a curvetype of absval to get its absolute value. Since it goes from -100 to 100, being 0 when centered, this gets us the deflection on the stick.
Second, we want the same for the elevator, which looks surprisingly similar:
[mixer]
src=ELE
dest=Virt4
usetrim=0
muxtype=max
curvetype=absval
points=0
The only difference is that the muxtype is max which means the output will be the larger of the output from the aileron mixer and this one. So we now have the larger of the two cyclic deflections.
Last step - let's compare this to some other value, so that it's only positive if the deflection is larger than that value. Instead of hard coding the value into the mixer, we can use the knob next to the flight mode switch, which is AUX5:
[mixer]
src=AUX5
dest=Virt4
scalar=50
offset=-55
usetrim=0
muxtype=add
This mixer uses the scaler setting to make the value go from -50 to 50 instead of -100 to 100, and then the offset setting to move it to -105 to -5. And the muxtype is add, so this will be added to the larger of the cyclic deflections.
So we now have a switch that goes on with cyclic input, and we can adjust how much input it takes to turn it on with the AUX5 knob.

Controlling the mode

The mode is a bit more complicated than before, or the above. The standard behavior uses two switches and three mixers, like so:
[channel5]
reverse=1
max=100
min=-100
template=complex
[mixer]
src=AIL
dest=Ch5
scalar=0
curvetype=fixed
[mixer]
src=AIL
dest=Ch5
switch=FMODE0
scalar=-100
usetrim=0
curvetype=fixed
[mixer]
src=AIL
dest=Ch5
switch=FMODE2
curvetype=fixed
The channel is reversed, because that's how the manual said to do it, though it's not really required when using devaitionTx. The first mixer sets the output to 0, which is the high-angle stability, or blue mode. The second mixer - enabled by the flight mode switch being in the 0 position - sets the channel to -100, the value for the low angle stability or green mode. The last mixer - enabled by the flight mode switch being in the 2 positition - sets the channel to the default value of 100, the value for the agility or red mode.
We now add a mixer:
[mixer]
src=AIL
dest=Ch5
switch=Virt4
curvetype=fixed
This one is enabled by the virtual switch we set up previously, and sets the output to the default value of 100, effectively switching to agility mode when it goes on.
I added this mixer after the first mixer, so that only the blue mode gets the stagility behavior. If it were added after the second mixer, both stability modes would actually be stagility modes. Added after the last one, and agility mode would also automatically switch to agility mode, for whatever that's worth.

Video proof of working

Here's a video showing off the four different behaviors I use. There are probably more:

The four behaviors are:
  1. stagility dialed all the way down, and it's just stock high angle stability mode.
  2. stagility dialed all the way up, and it's an auto-leveling agility mode.
  3. stagility is tuned by pushing the aileron all the way out, then turn up stagility until it switches to agility mode. This causes it to switch to agility mode when the sticks are at full throw, which usually results in an immediate flip. This is a behavior seen on some of the RTF "toy" quadcopters.
  4. stagility set somewhere in the middle of the range, and it behaves like the versions that mix the cyclic controls into the mode control channel.

My DeviationTx model

Warning

There are reports that using stagility mode can cause your quad to become unstable in flight. According to the support peopel at Horizon Hobby, this can be permanent, requiring reflashing the quad firmware to fix. While I believe that this variant doesn't have that problem, nobody knows for sure, so understand you are USING THIS AT YOUR OWN RISK.
That said, if you use deviationTx you can download my model for the Devo 10 here.

Monday, June 23, 2014

First impressions of the Blade 200QX


Blade 200 QX

The 200 QX arrives

I had pre-orded a 200 QX for a number of reasons. Now that it's here, I'm quite happy I did. It's a cute little thing:

For those not familiar with it, the 200 QX is Blade's latest quadcopter. It's in the same class the 180 QX and their first quad, the m QX and the WLToys v959.

Overview

While the size temps me to call this the latest in their m QX line of quads, it actually has far more in common with the 350 QX than the m QX or it's successors:
  • It has the same hard, white shell instead of a cheap plastic canopy.
  • It uses brushless motors.
  • It uses a multi-cell lipo.
  • It has three different flight modes, not two.
It really looks like a miniature 350 QX:
Blade Brothers
Blade 200 next to a 350 QX with a red skin.

Hardware

I like the hardware. For some reason, the plastic feels sturdier than the 350 QX plastic. Possibly it's just the smaller size making it a little bit firmer.

It has very high-speed (3000Kv!) brushless motors, so the props seem ridiculously small. However, they provide plenty of oomph. It sounds more like a Nano Qx than anything else.

Blade fixed what I thought was most annoying about the 350 QX (I know that other people have much more serious problems than I did): the battery cover latch is actually solid. I've had more than one 350 QX flight end without a battery cover, even though they started with one. The 200 QX battery cover latches down solid, and has shown no signs of such a problem.

On the downside, it has no power switch. Having to plug it in and then try and get the battery hatch on and the thing on the ground before it goes into bind mode reminds me of the toy quads.

Flight

The thing is an absolute joy to fly. It does mimic the 350 QX in having three flight modes, one of which is pretty much useless. But it's also stable and responsive like the 350 QX in the modes I do use. The unused flight mode has a limited flight envelope - so you can't get in too much trouble, or go too fast as well as automatic stabilization when you let go of the sticks. There is a middle mode where the limits are much higher. The documentation says "maximum limits", but as far as I can tell it still falls short of acrobatic. This mode also automatically levels the quad if there is no directional input. Finally, it has a mode with no limits - and no automatic behavior. You have the full flight capabilities at your fingertips, and can do all the acrobatics your heart desires. When in this mode the 200 QX feels like a collective pitch helicopter. It doesn't stop doing what you tell it to until you explicitly tell it to stop.

Unlike the 350 QX, there is no hands-free mode, or return to home feature. However, switching to one of the stable modes will cause it to go into a mostly stable hover, and still acts as a safety net.

The obvious comparison would be with the WLToys 959:
Not Brothers
200QX and a WLToys v959


Except there is no comparison. The 200 QX costs nearly four times as much, without a transmitter or a camera. I'd say it's easily four times the craft. It's not clear having a real body instead of a cheap plastic canopy is a win, but the brushless motors that give it it's character cost more than 5 times as much - even if you buy cheap Chinese clones of the Horizon Hobby motors the 200 QX uses.

And it has such a nice character. Lots of oomph, and a serious punch out. It has enough lift to carry a GoPro camera. Unlike the v959 and its ilk, this is a hobby grade quad. Yes, both have enough power to do flips. But on the toys, you have a button that makes the thing flip, so you can show off to your friends - but otherwise that power isn't available and it's constrained by an autoleveling feature. On the 200 QX (and the 350 QX, and the Nano QX) you have a mode where you get all the power you need to flip. Or loop. Or roll. Or whatever. But you have to actually be able to fly the quad to do it.

Aside from acrobatics, the 200 QX feels much more stable than the v959 - at least when in one of the two auto-leveling modes. To be fair, the v222 would be a better comparison, but I'm not interested enough in those to buy one.

Camera

Sorry, didn't get one. I couldn't convince myself that it made sense since I already have a 350 QX and GoPro.

However, that the 200 QX provides an external servo interface connected to the Aux channel opens some interesting possibilities for adding my own gadgets. The same could be done with the v959, but the interface isn't standard, and I'd be surprised it has enough lift to get a GoPro off the gound (let me know if you do that). Watch the blog for future reports.

Summary

Ok, it's expensive. This isn't something you'd buy to see if you're interested in flying RC multi-rotors. Not unless you've got a lot more cash to burn than I do. For that, the NanoQx is a lot better buy. On the other hand, I think it makes a much better second quad than the v959. If you start with the Nano QX, the v959 will be a disappointment. This won't.

Monday, March 3, 2014

Review of the Nine Eagles SoloPro 126 V2 Night Version

The helicopter

Having gotten comfortable with the Walkera Mini CP, I've been looking at getting a second CP heli for a while. While I've narrowed the choice down to three, nothing seemed to leap out and shout buy me. The Nine Eagles 126 V2 Night Version was on the initial list because of the spiffy night flying look, but didn't make the short list.
Until the RTF version went on sale at miracle-mart.com for $133 dollars.
There's actually a bit of history behind this helicopter. It's the brushless version of the SoloPro 125. That helicopter is better known in the US as the Axe 100 CP, sold by HeliMax, who licensed it from Nine Eagles. It has gotten some solid reviews. The brushless version is the SoloPro 126/Axe 100 SS, and the helicopter I'm reviewing is licensed as the Axe 100 SSL.
The Axe versions use SLT, meaning using my transmitter would require getting the Tx-R version and an AnyLink adapter to fly it with my controllers. The Nine Eagles version uses the J6Pro protocols, which my Devo 6S running deviationTx can fly. The little I've heard of Nine Eagles indicates they are of higher quality than the HeliMax versions. And LEDs!

The J6Pro

Since this was an RTF model, it came with the Nine Eagles J6Pro controller. About all I can say is yuch. This is the only computerized controller I've encountered that felt like a toy controller. Mine is now listed on craigslist if you want a really cheap full-size computerized controller.

The SoloPro 126 V2

My first reaction to the 'copter itself was "Wow. It's a lot bigger than I expected." While it's a 100-class CP heli, it's noticeably bigger than the other 100-class heli's I have - most notably the Walkera Mini CP and a number of WLToys V911 configuration. Other than the size, it's a pretty standard pod and boom helicopter.
Here you can see it next to the Walkera Micro CP and the very popular WLToys V911 to give you an idea of its size: V911, Micro CP, 126V2
The V911 (well, Y911 actually) looks as long as the 126, but it's tail sticks up a bit, whereas the 126 sticks straight back, so the it the V911 looks longer from this angle. While the blades are all about the same length, the pod & boom on the 126 is noticeably longer
Here we have a side view, showing the tail boom sticking straight back instead of up. You can see the three dimples for the LEDs on the end of the near blade: 126V2 side view
And here's the detail on the tail, showing the tail LED: Tail closeup
Finally, here's the pod without the cover. You can see the receiver/etc. board sitting in front, and the ESC in shrink-wrap sticking out below it: Naked

LEDs

On the off chance you haven't seen videos of it, the 126 V2 has three LEDs on the end each blade: Green/Red/Green on the bottom of one, and Blue/Red/Blue on the top of the other one. They appear to be driven by the current driving the main rotor, as they shut off when it shuts off. There is also a red LED on the tail, which shuts off when the tail rotor shuts off. All very pretty.

Quality

The quality is - well, intermediate. Given the raft of really tough micro and nano 'copters available recently, the 126 V2 doesn't stand up very well. The blades seem a bit brittle, and the main rotor links have a nasty habit of coming off easily. On the other hand, the landing gear seems to be made of very resilient rubber - or at least something with a lot of give. I expect it will last much longer than the the gear on other 100-class 'copters.
One oddity I found: the blades are not interchangeable. The power lines for the LEDs have different lengths, and the shorter lines won't reach the plug if that blade is used on the wrong side.

The manual

The manual is the usual Chinglish garbage. Pretty much worthless. On the other hand, the HeliMax manual for the Axe 100 SS/SSL is quite readable English, and includes detailed disassembly and replacement instructions that work quite well on the 126 V2. For the most part, the only part of the manual that's not applicable is the coverage of the receiver and controller, as HeliMax replaces the receiver firmware with an SLT protocol firmware, and uses the corresponding controller. Since I'm using a controller with the deviationTx firmware (as always), this section of both manuals is pretty much worthless to me anyway.

Parts

Since HeliMax sells a licensed version in the US, the parts are locally available and work just fine. I've been using HeliMax batteries for a while, and have the HeliMax blades and rotor links on it now. A lot of the time, I can wait for replacements, so ordering them from Miracle Mart at 1/2 to 1/3rd the price of the HeliMax parts (even with shipping) makes sense.

Flight

It's a little bit less stable than the Mini CP. Not a lot, just enough to notice. On the other hand, with the same controller settings, it's a lot more responsive. If I hadn't flown the Mini CP before, I might even call it twitchy. I definitely wouldn't recommend this as a first CP heli.
It's a very nice step up from the Mini CP. Even better, it gets much longer flight times: while I'm still flying it very gently, I get 6 to 7 minutes from a battery.

Summary

I like it. I'm glad I bought it, and hope to get in some night flights in the near future, though that may have to wait until summer.