It’s been forever since I updated this, so a quick pictorial review of things that have happened:

Jailbreak!

I soldered this in.  It pushed the limits of my hammy carpenter fists, but I think I did pretty well.

I soldered this in. It pushed the limits of my hammy carpenter fists, but I think I did pretty well.

I modified our cheapo Turnigy 9x transmitter so that we could flash it with open-source ER9X firmware.  This transmitter uses a fairly generic microcontroller for its “brain,” but the firmware it comes with is clunky at best.  The RC geek community has come up with far better options, some of them pretty specialized.  ER9X does way more than I’ll ever need, and is very intuitive once you get used to it.  Hobby King is now selling a fancier version of the transmitter with the open-source firmware installed, and not giving credit to the community that developed it.  Imagine, a corporation taking open-source code and pretending they own it!  Unheard of!

Don't worry, I'm a professional.  I've owned this Dremel tool since I was about 13.

Don’t worry, I’m a professional. I’ve owned this Dremel tool since I was about thirteen.

An AVR programmer (connects the microcontroller to your USB port) plugs into this funky plug.  I guess the cool kids just build the programmer into the transmitter and have a USB plug on the outside for computer connection.  Ironically, I couldn’t get my AVR programmer to work with Linux, so I had to use the evil Windows to flash the transmitter.  Now, I can actually program parameters for different aircraft (including any sort of multi-copter, etc.) from my computer.  Not that I’ve actually done that.  Seriously, this is powerful stuff, especially for the DIY drone crowd.

Please don’t think that I have more than a vague idea about how this stuff works.  I prowled numerous forums and watched many videos to figure out how to do this.  I was just following the recipe.

Nothing says "craftsmanship" like big globs of hot glue.

Nothing says “craftsmanship” like big globs of hot glue.

 

The final result.  Totally pro, right?

The final result. Totally pro, right?

 


 

 

 

 

 

 

 


Flying
!

So we flew a couple of more times (still just me actually flying), then this happened:

 

Pride goeth before the fall, or some shit like that.

Pride goeth before the fall, or some shit like that.

 

Followed by heroic rescue by Guthrie.  We had to leave the plane overnight and come back the next day with more equipment.

Followed by heroic rescue by Guthrie. We had to leave the plane overnight and come back the next day with more equipment.

 

 

 

 

 

After the successful rescue, we fixed the plane, and finally made it out to fly.  Since the plane would have been a total loss without Guthrie’s rescue efforts, I figure he owns it now.  I nagged him to do some simulator time, which he did, probably an hour total.

The freeware RC plane simulator is dull as church.  It’s not like a fun game with an airplane, but it does help with the basics, especially getting the hang of steering when the plane is coming right at you.  It’s actually in some ways more difficult than flying the real plane, because the simulator plane is hard to see in context.

The weather was perfect for Guthrie’s first flight – very light, fairly steady breeze and lots of sunshine.  I took a couple of circles around the field to trim the airplane up, then managed to snag the landing gear in some blackberries on approach.  The plane was fine, but we lost a wheel in the thicket, so all subsequent flights were hand launched and landed in the grass.  Hand launching is actually much easier than taking off from the ground, just keep your hands well away from the propeller.  Once I was confident the plane was flying straight and level hands-off, I handed the controller to Guthrie and he flew from then on.

Next time, sunglasses.  It's really easy to lose the plane in the sun.

Next time, sunglasses. It’s really easy to lose the plane in the sun.

 

The boring simulator time really paid off.  Guthrie was able to fly in slow circles, and even did a coupld of decent landings.  All his crashes were gentle.  I never touched the controls after he took over.

The boring simulator time really paid off. Guthrie was able to fly in slow circles, and even did some stalls and a couple of decent landings. All his crashes were gentle. I never touched the controls after he took over.

The takeaways from all this are that Guthrie clearly has amazing natural flying talent, and that the simulator really works.  I got a Futaba “transmitter” box with a USB plug from the Goodwill for $8, and there are a few different free software options.  Sadly, I couldn’t get anything to work with Linux (I think it can be done), but it works fine with Windows.

If you’re thinking of doing one of these planes, definitely get a simulator going.  If you can fly the sim, you can fly the actual plane.  Not that there won’t be crashes, but the happiness/frustration ratio will be much better.

Gratuitous Mt. Hood shot.

Gratuitous Mt. Hood shot.

Our original airplane, the Axon, has finally died after several outings since the last update – its final flight ended in a giant hedge of blackberries (downwind stall and spin in a gust), and Guthrie bravely, with a little bloodshed, extracted the wreckage for salvage – he had to yank the plane out by its tail, and it got pretty well shredded.  Now we now know how much wind is too much – 14 gusting to 20 mph is too much wind, at least for my piloting skills.

We actually repaired the Axon after this crash, and flew it a couple of more times.

We actually repaired the Axon after this crash, and flew it a couple of more times.  It’s wing, tail, and landing gear will be salvageable.  The electronics are all fine.

Meanwhile, I’ve been chipping away at a plane of my own design.  I’m calling this new plane the Bee (original, I know).  It has a shorter, wider, thicker wing with quite a bit more area (7 x 48 inch Armin wing for you geeks).  I also built the wing with about 5 degrees of dihedral, for better stability.  The idea is that this would be a slower, gentler plane, that we could possibly fly at a vacant lot within walking distance of the house.  The Bee was built with the same basic methods and materials as the Axon, (Dollar Tree foam board, hot glue, packing tape, duct tape) -

 http://www.youtube.com/user/ExperimentalAirlines

- I can’t give enough credit to youtube cult hero Ed for developing this method.  I did use carbon fiber rod for the wing spar and landing gear.  I used about $4 worth in the plane, and it should be reusable, barring a truly catastrophic crash, so total airframe cost is probably still in the $10 range, not counting the $6 wheels.   In spite of my overbuilding and over taping, the Bee started out about 100 grams lighter than the Axon at 950g.  It has a slower-turning motor, which is theoretically less powerful, but actually seems to produce about the same amount of static thrust, which I measured at 800g by holding the plane nose-down on the kitchen scale and opening the throttle.  I have much to learn about electric motors and propeller sizing, but the Bee will have plenty of oomph.  I mounted the motor high to protect the propeller and motor in crashes, but forward of the wing to concentrate the mass toward the nose.  The Axon was really designed to carry a camera and extra radio gear  in its nose for FPV flying, whereas the Bee is strictly intended as a line-of-sight RC plane, and concentrating the heavy parts should reduce the pendulum effect.  I tapered the fuselage sections for looks and to reduce weight.

The Bee under construction.  The idea was to mate the upper and lower fueselages in such a way as to achieve the correct (ish) center of gravity.  Didn't really work out.

The Bee under construction. The idea was to mate the upper and lower fuselages in such a way as to achieve the correct (ish) center of gravity. Sound concept, though my execution proved lacking.

The winds have been relentless in Portland for the last week (no doubt related to the creepily warm temperatures), but the Bee finally flew on Friday, May 3, at our usual undisclosed location.  We had driven to the spot a few days before, but I was scared to fly in the high winds, especially after the death of the Axon.  On Friday, the winds were light, with occasional gusts.  On the first flight, the Bee shot into the air and quickly climbed to about 75′.  I turned it downwind, and realized that the plane was crazy twitchy in pitch and roll.  I tried to steer it back, but soon gave up and just shut off the power to let it glide into a farm field.  I’ve learned that the gentle crash is preferable to the hard “landing.”  My decision to crash-land came after Guthrie said “um, Dad, the plane is upside down.”  Oh, yeah.  No damage in the crash, just let it sort of flutter into the weeds.

PreFlight

Glamour shot before the maiden flight. Note the big ol’ barn door ailerons.

Realizing that we were seriously tail-heavy, I moved the battery as far forward as possible, put a small rock in the nose, and turned the ailerons down to 75% throws.  Much better.  Landed and put a couple of more small rocks in the nose.  Beautiful.  When we got home I weighed the rocks at 30g.  When building the plane, I did all sorts of research about where to put the CG, but I was still a bit off.  If I rebuild this plane or build another like it, I’ll know to put the lower fuselage further forward, with room to move the battery back and forth for fine tuning.

With nose weight, the Bee flew really well.  It generally went where I pointed it, and kept its trim with power on or off.  It quickly self-recovers from stalls, just let go of the sticks. Unlike our Axon, the Bee rolls without losing much altitude, which makes turns really easy.  Very aerobatic, at least by my newb standards.  The winds were really starting to gust by the end of our flying session, and the Bee did really well.  It wants to float (and float, and float) on landing, even more than the Axon, so some sort of flaperons may be in the works.

I’m not sure that I can fly it in our local vacant lot, at least with my current skills.  It’s a bit more forgiving and not quite as fast as the Axon, but the Bee covers a lot of ground quickly, and flies quite fast under power.  It would be easy to lose it in a tree or on somebody’s roof.  But maybe with more practice…

Takeoff

Takeoff!

LowPass

Low pass. Note the actual airplane on the right. We avoided collision by mere miles.

 

With a close eye on the weather radar, Guthrie and I decided to go flying this afternoon.  We spent about twenty minutes repairing and reinforcing the plane with hot glue, bamboo skewers, duct tape, and some popsicle sticks and headed out around 2:30.  After a fairly sunny morning and forcast for a decent afternoon, we drove through rain and hail to our flying spot.  We sat in the truck through some more hail, then discovered that the electronic speed controller had come loose from the plane.  We fixed it with some double-sided tape, then sat in the truck through still more rain, hail, and gusty winds.  Finally, the dark cloud passed and it was time to fly.

Hacked together and ready to go!

Hacked together and ready to go!

The first flight ended fairly quickly in a relatively gentle crash, and this was the only crash of the day.  The many other flights ended with actual landings on the “runway,” though some landings were far prettier than others.

In the crash, the battery mount came loose, so we fixed it with double sided tape and duct tape.

In the crash, the battery mount came loose, so we fixed it with double sided tape and duct tape.

I  got fairly comfortable flying the plane around, doing some low passes, and even a couple of loops and rolls (intentional this time).  Guthrie wanted me to do a roll during a low pass so he could take a picture – uh, no.  While it wasn’t super windy, there was a light breeze and some gusts (maybe 5-7 mph, according to wunderground.com), and the plane handled them really well.  It’s smallish as RC airplanes go, but it’s big enough and stable enough to handle some wind, even with its long wing.  A common beginner mistake is to get a teensy little airplane – a bigger plane is actually much easier to fly, and easier to see at a distance, which is important.

LowPass

Low pass for the camera!

 While I still have a long way to go as an RC pilot, I think we had a really productive outing today.  We actually depleted the battery to the point where the electronic speed controller (ESC) started reducing power – LiPo batteries don’t like to be discharged beyond about 80% of capacity, so the ESC lets you know when to quit.  There were many takeoffs and landings, and lots of controlled flying around.  I got out of several hairy situations without panicking or over-correcting.  There are some issues to fix.  The plane pitches up under power, even though it glides really well with power off.  I think I need to adjust the thrust angle of the motor mount, and maybe move the CG forward a tad.  The pitching up isn’t all bad, since if I hit the power, the plane will climb, but it makes low passes and fast flying difficult.

This was not one of the pretty landings, though I did get it straightened out a bit.  I honestly never noticed how the color scheme of the plane matches my truck.  Draw your own conclusions.

This was not one of the pretty landings, though I did get it straightened out a bit. I honestly never noticed how the color scheme of the plane matches my truck. Draw your own conclusions.

Guthrie is getting pretty annoyed that I won’t let him fly the plane yet.  I was once eleven, and I feel his pain, but I’ve tried to explain that the experience will be frustrating for him, and result in the total, final destruction of the plane.  While anyone can learn to fly an RC plane, the initial learning curve is very, very steep.  I’ve found that I can get a cable to connect our transmitter to a computer and use any number of free RC simulators, so I’ve ordered the cable (from Hong Kong, of course), and I’ll let the kids have some simulator time before they get to destroy the plane.

DSC_7010

This is Very Serious.

 

For the past couple of weeks, we’ve been slowly building a radio controlled airplane, primarily out of foam board from Dollar Tree, packing tape, plastic gift cards, and lots and lots of hot glue. You can use plain old clear packing tape, but I ordered some colored 3M tape to make things more fun. There’s also a fair amount of duct tape on the airplane (more to come, no doubt), and a bit of double sided tape and sticky Velcro for mounting things. We used super cheap Chinese electronics (is “Chinese electronics” redundant?) from Hobby King, which are way nicer than the high-end stuff from my youth. The actual airframe probably cost less than $10, and the more expensive stuff will likely survive to be reused in the next airplane. Having built one of these, I bet I could knock one out in a couple of evenings if I really focused. It’s fun, crafty work and the kids helped, especially Tape Meister Guthrie.

 

I didn’t come up with this scheme myself, but followed the techniques of Ed of http://www.youtube.com/user/ExperimentalAirlines . Ed is a crazy mad genius cheapskate geek of RC airplanes, and his how-to videos are well-organized and exhaustive. Our plane is a slightly modified version of his “Axon.” We made the wing a couple of inches longer, and our fuselage three inches shorter than his specs. We also put on some pretty beefy landing gear, because taking off and landing is fun, and it helped balance the airplane. I really appreciate the open-source approach that Ed promotes. Just dive in and build it.

1stFlightHydrant

The very first flight. Amazing precision to hit such a small target.

 

Today, we went flying. Well, I went flying, Guthrie watched and took some pictures, and Sayer wandered off into a swamp. Flying an RC airplane is not easy, and we built this plane with the understanding that it might not survive its first flight. That’s the whole point of the cheap airplane. I hadn’t flown for well over twenty years, and I never flew enough to get very good at it back in the day. In spite of the “disposable” airplane, I was really nervous. My hands were literally shaking on the first few flights, which certainly didn’t help. The very first flight, I crashed right into a fire hydrant, the only solid object within fifty feet (gotta use the rudder on takeoff). After the first “real” flight and crash, I moved the battery way forward, and programmed the transmitter for 70% control throws, which made things much less twitchy. Roll, especially, was very responsive (there was one accidental barrel roll). Several crashes later, some semi-controlled, I finally got my nerves settled (the plane was damaged enough that I didn’t care anymore), and actually started to fly. With minimal trim the plane would basically fly hands-off. Most problems were caused by my interventions and over-correction. I used the controls to make “suggestions” to the plane, and it worked really well. I made three decent landings (four if you count the one after the big bounce). The hardest part about landing is that this plane glides like crazy. At around 1050g, by the kitchen scale, I thought we were a bit heavy, but after shutting off the power, the plane just goes and goes. The battery was never depleted, and I decided to quit while I was ahead, though the plane was still quite flyable. After some hot glue, bamboo skewers and duct tape, I’ll be back for more.

Takeoff!

Takeoff!

Final Approach

Turning on to final approach.

Landing

Gliding in to landing. Really, this one was pretty good.

Recovery

Recovery crew. He was pretty busy.

NoseAfter

The nose after many crashes – this was after the last flight. I fixed it once with red duct tape. I was worried about the battery being way out there (to keep the center of gravity forward). These batteries tend to catch fire when abused (ala Boeing 787). This plane took an amazing amount of abuse, and it will fly again.

I’ve promised the kids that once I learn to consistently fly and land, I’ll give them a go at it. We’d probably better build a back-up airplane first.