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| Old Popwing has seen better days, but now I'm in love again! |
"Wow" a young boy screamed as my Popwing took off like a bat out of hell from the local park. Though he was impressed, I certainly wasn't. After nearly crashing into the ground the plane shot up to around 40 feet. "Too much up-trim," I thought to myself. I landed it, and moved the control surfaces down even closer to level and shot it off again, This time with less throttle. A nice toss and the plane was performing well. I set some radio trim and figured out what was off. The control surfaces were a bit too flat, after landing I brought the control surfaces up slightly. My third takeoff was fine. The plane was flying well. There was no trim, no expo, and I was at full rates. "She's ready," I said with a smile. I enjoyed the rest of the flight as I thought about what I was going to do with her that night.
Later on that night.
I cut the zip tie that held the receiver. Though it wasn't a bad receiver it wasn't what I needed. I spent around 20 minutes getting my SeroiuslyPro Racing F3 flight controller ready. By now I've been through the INAV setup enough times to have it down cold. Still, I put a sick amount of modes on my FrSky receiver and it took another 20 minutes o get them all turned on. The old receiver came out easy enough (it was held down with Hook & Loop and a zip tie on the bottom of the plane in the cutout compartment0. The SPRacing F3 has a nifty case, and with a little hook and loop it took roughly the same spot, with one small problem, Since it was on the bottom of the plane it was upside down. This means the plane will think left is right and right is left. In the configuration tab in INAV I simply changed YAW by 180 degrees and that solved the problem. I used E6000 to glue down the XM+ receiver to the bottom of the wing. It's tiny. The only real mod was to take a very small drillbit and hand drill a small hole from the compartment my flight controller and ESC were located. I passed up one tiny cable. It went to my GPS unit. The GPS unit needs to be on the top of the wing so that it can see the satellites.
Here's the wiring, in detail.
#1. Plug in ESC into the flight controller (S1)
#2. Plug in GPS Unit into flight controller (plug on side of controller)
#3. Pug in servos into the flight controller (S3 & S4)
#4. Plug in the receiver (one cable) into the flight controller. (special cable that comes with the flight controller, plugs in side of controller)
If you're counting, that's five plugs to plug in, that's it! It truly is that simple.
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Aside from the rat's nest of wires the F3 fit right in
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The re-maiden flight
It was a day with rain in the forecast. For the record, Southern California, a place where it never rains has seen 3 months of on and off rain, mostly on. I had my shoring up flight the day before, and now, at face value, it was time for its INAV maiden. Would the proper trim from another receiver transfer over to INAV using the FRSky transmitter and recevier? Would the flight controller have its own ideas as to what was servo-center? I guess we'll find out!
With a good toss the plane was off and flying. It was a tad tail heavy so I landed it and moved the battery forward. This time all was well. She was off and flying pure and smooth. It was so nice that I hesitated to do what I had to do next, turn on stabilization. The key to doing this is to fly it over grass because it may come in for an abrupt landing. With a flip of a switch "aaah, even nicer!"
There was good, and then there's even bettter. I was seeking as close to perfection as I could get with this plane. It had a lackluster motor on it which made it fine for a floater, but it certainly didn't fly fast. The best thing I could do was to make this a smooth flyer.
What a flight controller can and can't do
If a perfect plane flight is 100% and your plane is at 60% of it's potential the flight controller really won't help get you to 100%. Maybe 70%, if you're lucky. I used to be happier with planes that have marginal flight characteristics, but not anymore. If I can get a plane to 90% the flight controller will help round out the flying experience, bringing the plane closer to 100%. The point is to use the flight controller to make a good plane better than to make a bad plane fly well.
Servo Autotrim
When we get a new plane we tend set it up as best as possible and then take it out for the first flight. When the plane is in the air we discover it's still not right and then set the trim in the radio. What the trim setting in the radio is doing is permanently make small adjustments to the control surface positions by compensating in the radio. The transmitter is a low-level computer that keeps track of these settings. What is different is that with a flight controller, the computer is moved to the plane. Thus the transmitter defers most of its decision making to the plane's computer because it's a better computer. But along with great power comes great responsibility. It's a bit more work to set up the flight controller and refine flight characteristics. Thankfully, INAV helps out with this task.
This may sound counter-intuitive but the way a lot of planes are designed, level flight actually causes the plane to pitch down a bit. Thus, there needs to be a certain amount of up-trim added to prevent the plane from losing altitude. We tend to do this when we first fly a plane, we'll give the plane some uptrim with our radio trim buttons. Part of my exercise from the day before was that I found what I felt was the very best setup of the plane. I set trim, then when the plane was landed I set the control surfaces to where the radio was trimmed. Then I set the radio trim back to zero. It took three flights and it was close to perfect. My servos arms are at exactly 90 degrees from the plane. Everything was ready. So, why do I have to go through trimming a plane if the plane flies well in manual?
Flight stabilization can make things worse, at first.
The plane flew great in manual mode, which meant that I had total control of the plane's control surfaces. When I switched into one of the gyro-stabilized modes the plane did the best job it possibly could. But, perhaps the flight controller isn't exactly pointing straight, and sometimes the flight controller isn't exactly situated at the center of gravity. And when these things occur, sometimes you make things worse when you attempt to fly in a flight stabilized mode. A lot of people get to a point in INAV where they give up right about here. They just fly in manual and use the features they like and forget about the flight stabilized modes. They are missing the best part! Getting this sorted out isn't difficult, and with INAV 2.1 complex PIF settings are calculated for us using the Auto Trim feature.
Refinement
I calibrated the gyro before putting it into the plane. And the plane is certainly setup right, so what more do I need to do? If I like to only fly in manual, the plane is ready. But, just like when you get into a new car for the first time, you have to adjust the mirrors, the seat, the heater or air conditioning. The car works fine, and you know how to drive, but still, modifications are needed, you just need to get it set for your situation. This exactly what needs to happen with a new flight controller in a plane. It has to make minor refinements. INAV has a simple way of doing this. You have to teach the plane what stabilized flight looks like.
Turning on Servo Auto Trim.
I took the plane out, I got it flying level, and then I turned on the Servo Auto Trim and flew level for at least a few seconds. What was happening in these few seconds was the plane was learning what level flight looks like and then made adjustments. I then landed the plane, disarmed the flight controller, and shut off the Servo Auto Trim. Then I took off again. It was a bit windy the first time I did it. It worked okay. The second time I did it there was no wind, and that time I really got it. The plane flew great in the stabilized modes.
Turning on Auto TuneThe problem I had with this build was with the weather. We had an extended rainy season and the days I could fly were often cold with an unstable atmosphere. One morning I had the most perfect flying day. Light, fluffy air, a mild breeze, it was nice and warm. In my haste to get things started I couldn't find my 1800mAh 3S battery. I instead went with the slightly lighter 1500mAh 3S . The plane flew without a problem. I got it up a couple of hundred feet in the manual flight mode and flipped on the horizon mode. It flew great, so I went for it. I turned on "Auto tune" and started flying. I kept flying in this mode for around 3 minutes. I noticed that I was at exactly half throttle. I needed a comfortable flying speed and for this lackluster motor half throttle was perfect! What is important is that Auto Tune needs to be set at a speed I will most often fly in, and for me this was perfect. Before I landed I turned off auto trim, then I l anded and saved the configurations. Then I disarmed. I armed again and took the plane up and did yet another servo auto trim. By the time I was done I was thrilled with the way this plane flew.
So, what's it like?
How did it fly? I've never had a Popwing fly this good! I had things trimmed at half throttle and the plane was Floaty McFloater. I flew the plane I didn't have to manage the flight. I hit the sticks when I needed to turn, but that was about it. It was like driving on a freshly paved road. When it was power off time, it was a nice, smooth stable landing. I did notice that the wind had picked up during the course of my flight. I just never felt it. I didn't feel like the entire experinece made things worse or took away the thrill of flying. About the only major adjustment, I had to make was waiting 30 seconds for my plane to find satellites and be ready to arm the first time I plugged in the batttery . If I were to change batteries and do another flight the satellites will be found much faster if I can swap the batteries in less than a minute.
Horizon ModeThis is a good, comfortable mode for flying. I find it to be the mode the balances the need for stabilized flight with the need to be hands-on during the flight. This certainly smooths the ride while allowing you the ability to feel in control. I was getting the plane flying straight as an arrow, and was using minor fluctuations in throttle to raise or lower elevation. Powering off the plane had a lovely glide back down. Part of this was the legenary flight characterisits of the Popwing/Teksumo. But mostly it was the flight controller making minor adjustments during flight on an ongoing basis.
Angle Mode
My experiences with Angle Mode thus far haven't been good. If your plane isn't well trimed and then autotuned and auto trimmed this mode will seize control of your plane and fly it very poorly. You will be out of this mode in short order.
But, when your plane is well trimmed this isn't a bad mode. Yes it does have limited banking angles and thus you need to account for that fact. But it wasn't horrific. It was actually quite pleasant. With this mode I would have no problem handing over the radio to the newest of newbies. They can get the feel of the plane and hopefully can lsiten to your input while figuring out how to keep the plane moving in the right direction and not crashing.
If anything, this mode is too smooth. When my buddy Cabo-Charlie invites me to Cabo San Lucas again, this is the mode we'll be flying in while drinking Coronas on the beach in our highback chairs.
Success! The point that shouldn't be lost was that this wasn't a plane that I planned to have flying with a flight controller. Yes, it does help that I knew my way around in INAV but the point is that planes which may not be good candidates for INAV FPV may actually be good candidates for INAV LOS. The reason I felt a bit compelled to write this is because a lot of people are cheering on the demise of the F3 flight controller in INAV. But here's a perfect example of an application where an F3 flight controller does work. If you can solder 24 pins, or if you have a friend who can solder 24 pins for you here's a cheap and easy way to get started with INAV.
Not everybody gets line-of-sight pilots
Instead of staring at a screen, or looking into goggles we're staring at the sky. There's something majestic about watching your plane float around in the sky. Not every plane needs a camera and video transmitter. With a flight controller, this doesn't need to change. Yes, I do have other full FPV rigs that fly. But there was a specific reason why I was interested in modding this plane.
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| Fugly but flies well |
This is my test plane
This Popwing certainly isn't new. It has it's battle scars. It's been in a few crashes but the largest problem is that it's seen a lot of use. Too many landings on tall grass have cut into the foam on the bottom and the edges. I have a few beloved planes like this. This is actually the perfect plane for INAV. There are many settings and wonderful modes to try out. The problem is, you really shouldn't be using your top shelf planes as your INAV test plane. The beauty of INAV is experimenting with new things. For this, you'll need a test plane. Something that is light and cheap. What better than a Teksumo or Popwing?
The entire setup was under $25 US.
The SP Racing F3 flight controller was $13 and the GPS unit was $9. Together, with shippiing, it's under $25 from Banggood. The more modern F722-Wing costs closer to $60 and isn't plug and play. Yes, it does a lot more and is better in every metric to the F3 flight controllers The F3 Flight controller is cheap and is a simple entry into the world of INAV. It runs the vast majority of the flight modes that are offered by INAV. This is a cheap, fast and easy way to get into computer controlled flight.
The things you need to know before jumping in.
The F3 will only support up to INAV 2.1 As of March of 2019 the programmers at INAV have decided that all future releases of INAV will not be offered to those using F3 flight controllers. Since the F3 represents older technology hardware they wish to continue their efforts with newer technology that is a bit more robust amonts of memory.
You will be able to download INAV 2.1 for the F3 flight controller for some time to follow. Thus, if you need to reload INAV onto your flight controller, you'll be able to download it.
The F3 flight controller doesn't come with an OSD- One of the cool aspects of INAV is the on-screen display that you use in conjunction with a camera and video transmitter. You can add an OSD to the F3, but it does require wiring and programming. If this is the route you are going it's better to buy an F4/F7 board with an OSD built in.
You will need to solder 24 pins- If you've never soldered before this is a great way to learn. If you blow it, you're not out as much money as one of the more capable boards. If you can't solder, you'll need to have someone help you.
The SPRacing F3 is a clone- The original F3 racing isn't made anymore. I have speculated that the F3 clone is actually a better board because it may use newer hardware. I have a few of them, they work fine. But, your results may be different. Clones always have a degree of uncertainty.
You may need a new radio and receiver- The flight controller needs switches and knobs to work. You use the switches to work with the different modes. Most traditional radios have somewhere between 4 and 8 channels. Each channel needs a servo wire hooked up to it. That means, if you want to work with 8 channels, you'll need 8 wires coming from your receiver. The newer style of radios are serial based. There is only one cable the receiver needs to offer the flight controller. Your servos and ESC plug into the flight controller. The wiring is much easier. On that one wire upwards of 16 channels can be used! You will need to check and see if your radio system is serial based. Some are and some aren't. The very inexpensive Flysky FS-i6 and Turnigy TGY-i6 are both serial based transmitters Some of the receivers are and some aren't.
You will have to challenge yourself to take on a learning curve- Knowing how to build a plane and getting it flying is step one. You will have to do some computer work to get the flight controller ready. You don't have to have an electrical engineering degree to take on INAV, but just the same, you won't figure this out in one evening. This has to be something you want to do and you will have to apply yourself.
INAV Fixed Wing Group on Facebook
We've created a group on Facebook that now has over 1000 members within the first few months. Our group is made up of pilots from every continent and nearly every corner of the globe. Our members have come up with a setup guide for INAV as well as video tutorials. Since we found people with the same issues over and over again we came up with a troubleshooting guide for INAV. Though you may not live near any of our members you will get the support of the community. Thus, if you decide to take on INAV you're certainly not alone. You can get help.
If you build and tinker with planes, you'll love INAV.
The people who like prepackaged planes (PNP) may not enjoy INAV as much as those of us who like to build. The sense of accomplishment is hard to describe. The first time you throw a switch and watch your plane turn around and fly itself back to you is mind-boggling. The first time you launch a plane and it flies itself to a certain altitude is mesmerizing. As our member, the famous Australian RC plane reviewer Andrew Newton once said of the auto-launch features "It never gets old!"
OverallIt's time to dust off your Popwing/ Teksumo. Even in today's world, the F3 board on the this plane is such a no-brainer. Once installed, you'll be taking your plane flying a lot more. If you're a line of sight pilot and have this plane it's nearly crazy not to put this flight controller on you plane. You will love it that much more! From this board you can move on to other planes. The learning curve you go through with the F3 flight controller will help you with the vast majority of INAV builds.
