Saturday, March 8, 2014

One year of RC planes

I just realized it's been a little over a year since I started messing with RC planes. Here's a summary of my experience so far. (Hint: it involves a bunch of foamcore and hot glue, a lot of crashing, and only a little blood.)

Before 2013 I had been flying small RC helicopters on and off for several years, namely the Blade mCX, the Blade mSR, and the Blade mQX. I found I enjoyed tinkering, fixing, and modifying the helis at least as much as flying them, which created a perverse sort of incentive to fly recklessly, since I wasn't particularly worried about the consequences of a crash. (I'd get a strange little thrill after each crash, wondering what I'd get to analyze and fix this time.) For a brief time I was into customizing the mSR with silly aftermarket parts (eg machined aluminum swashplates), but that got old pretty quick--what I really wanted to do was build things from scratch, maybe even things of my own design.

Building helicopters from scratch is a pretty advanced undertaking, and is nearly impossible at the scale I was comfortable flying. (I often need to fly near my kids if I'm going to fly at all, and so larger scale helis scare me.) Thus in early 2013 I decided to try my hand at RC planes.

With great hubris, I decided to start with a scratch-build. That is, the first plane I would fly would be one I built myself, not store-bought, and not from a kit. I discovered the excellent site Flite Test, which has plans and instructions for foamboard scratch builds, as well as a fantastic YouTube channel with build videos, challenges, reviews, and other great stuff. In particular, they have a design for a cool Swappable Power Pod and then a growing series of plane designs that can use that same pod.

To build the swappable pod, I had to learn all about RC aircraft electronics, how to use a hot glue gun (easy), and how to solder (I'm terrible at it). Here's my build of the swappable pod in action:

The first foamcore plane I built for the swappable pod was the 3-channel FT Nutball, which is odd and round:

It was also pretty wonky in the air. Keep in mind this is me as an extreme beginner with RC planes, with my first flight experience being on this weird wobbly thing:

Knowing what I know now, I suspect reducing the servo throws (how far the control surfaces move) would have made it much more docile. But I didn't know that back then, and in my zeal I quickly moved on to a second model: the slightly less odd, but still 3-channel, FT Flyer, which also used the swappable pod:

The FT Flyer flew much, much better than the Nutball:

I was even able to attach a GoPro camera to the underside of the FT Flyer and capture my first (loud, frantic) HD onboard video. It shows the field in our neighborhood where I fly. It's a decent sized field, but it's long and narrow and surrounded by trees, so it's pretty constricting for RC planes.

I've edited out the ending of the flight above, since it was slightly traumatic: the plane lost signal, dove straight toward me, and the blade cut deep into my right middle finger as it flew past. I still have the scar, but luckily I also still have the finger, and it healed without stitches.

At this point, still very much a beginner, I amped up the hubris and decided to start on my own design. What's more, I decided to build an aerobatic 4-channel modeled after the Yak 54. I knew such a plane would be too advanced for me, but I went for it anyway. I designed it in SketchUp, printed out the templates, and built it:

It was a non-trivial rib-and-skin design, and I chose to wrap it in paper which resulted in a lumpy appearance. I was proud of the The Lumpy Yak but it didn't fly well--I struggled (and failed) to keep it off the ground:

In retrospect, watching this video, it should have flown well, and it's clear why it didn't.
  1. It was very tail heavy, and back then I didn't understand aircraft balance very well;
  2. It was a bit heavy for the motor I was using, so it was underpowered;
  3. The landing gear struts were too long and too flexible, which caused problems on takeoff; and
  4. I was still a terrible pilot.
Knowing what I know now, and having improved as a pilot, I bet I could tweak the center of gravity and fly the Lumpy Yak just fine. Sadly, I stripped it for parts somewhere along the way.

Up to this point I had only flown scratch build planes, and with mixed success. I decided it was time to swallow my pride and buy a pre-built plane, designed and assembled by professionals, so I could practice my flying without worrying about the shoddiness of the aircraft. I opted for the popular beginner 3-channel HobbyZone Champ RTF. It was refreshingly easy to fly a well-designed plane, and I spent a lot of time practicing on the Champ.

The Champ is quite small, which means it can't handle much wind at all, so it's only usable on particularly mild days. On the other hand, it's small enough that it's safe to fly above my backyard and house, which made it even easier to get practice time in. The Champ is way too small to carry a GoPro, but it can (just barely) manage to carry a 808 Keychain Camera, Once I could fly the Champ comfortably, I mounted the camera and got some interesting (but shaky) aerial footage above the neighborhood:

Once the Champ started to feel too easy, I stepped up to the 4-channel UMX Carbon Cub SS. I honestly struggled with this plane, because it was a more challenging 4-channel (5 if you count the flaps) but still small enough to be knocked around by the wind. I only had a few flights with the thing before a crash knocked it out of commission, and after one round of fixes and then another crash, I lost interest and mothballed the Carbon Cub.

Meanwhile I was really getting into aerial photography with the Champ, and I wanted to step up to a bigger platform, something that could carry the GoPro easily. I built up my confidence and finally bought the much, much bigger ParkZone Radian. I was super nervous on its maiden flight, because it was so much bigger than anything I'd handled before. It flew like a dream, though, once I got over my nerves:

I immediately built a custom GoPro mount that can replace the canopy of the Radian:

The Radian is huge and carries the GoPro with ease. The GoPro cuts down glide times quite a bit, bit it still handles well, and I've gotten some gorgeous aerial footage above the Boyce Park model airfield, with a clear view of the Boyce Ski Lodge and (grassy-at-the-time) ski slopes:

During this period I was also working on my second custom design, a pusher-prop glider designed to carry the GoPro without a propellor in the way.

After some early frustration and a couple revisions, this custom-built plane flew absolutely beautifully, almost as well as the Radian itself.  And the design is pretty slick, if I may say so myself:

However, my first attempt to fly it with the GoPro was on a particularly windy day, and the results were humorous (but strangely beautiful):

The pusher glider had a nice shaped airfoil and got me exploring different airfoil designs. One Sunday near the end of 2013 I had an idea for a foamcore wing with polyhedral and camber, achieved with careful cuts and bends in the foamcore. On that same day I built a prototype of the wing and then threw together a "slow flyer stick" design to try it out, scavenging the electronics from the disgraced Carbon Cub. This was a really rapid prototype scratch build, from idea to flight in a single day:

I'm proud to say it flew really well. The motor was a bit underpowered and I'd like to iterate on the wing design (the front edge of the camber is too flat, creating too much drag), but it's promising.

As winter approached, I started practicing 3-d (aerobatic) flying in simulator (both RealFlight 7, and Phoenix 4), and finally got up the guts to buy my first 3-d model, the Edge 540 QQ. However, the Miserable Eternal Winter of 2013-2014 started right around then, so I wasn't able to maiden that plane through the whole endless winter.

This morning, in March of 2014, I finally got to maiden the Edge 540, and it was a ton of fun. It's not yet clear if spring is here for good, but I'm chomping at the bit to get the flying season going in 2014.

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