Gweek 155: The cheap RC plane I talked about

Posted: July 16th, 2014 | Author: | Filed under: Startups | 2 Comments »

Five years ago (!!!) I gave an Ignite talk on cheap RC airplanes.  In one of my prouder geek moments Mark Frauenfelder, a maker-hero of mine, posted it to Boingboing.   And that was that.

Until today, when I had the amazing opportunity to be a guest on an episode of the Gweek podcast with Mark and my good friend Dean Putney. We covered a lot of ground (Robot Turtles, Little Bits, Homestar Runner, EC Archives, and of course Potato Salad) but I had a particularly good bit of fun returning to the ‘cheap planes’ topic.  Except now, of course, for a few hundred bucks more, you can upgrade to a cheap UAV. You should listen to the whole show here:

LISTEN TO THE GWEEK

but there are some things a podcast just can’t do justice to properly, so here are some supplemental links. During the podcast I talk about my favorite plane.  I am on my second one; the first got caught up in surprisingly strong winds off the coast of Aruba and was lost at sea. It costs $20, and the electronics to fly it will run you less than $100.

Start with the plane.  This is the Turnigy Bonsai.  It is an elevon plane, meaning that the two flaps act as ailerons (one up/one down) or elevators (both up/both down). There’s no rudder, so to turn you roll right, then pull up. It’s easier than it sounds and a lot more fun than rudder planes. ($23.45)

HobbyKing® ™ Bonsai EPP Wing 600mm (ARF)  (US Warehouse)

The Turnigy Aerodrive SK3 – 2118-3100kv  motor will let it fly straight up… while accelerating. Note that it’s about twice as beefy as what the plane’s designed for so you’ll need a bigger battery too to offset it. ($14.25)

Turnigy Aerodrive SK3 - 2118-3100kv Brushless Outrunner Motor (USA Warehouse)

Props have two numbers. The first is diameter, which gives you lifting power. The second is pitch, which gives you speed. Increasing either puts more stress on your motor. This 5×5 APC-style prop will push our little 17g motor to its limits. Zoom! Be sure to mount it with the letters facing away from the motor. ($1.57)

APC Style Propeller 5x5 (2 pc) (USA Warehouse)

The aforementioned motor is actually a brushless AC motor (thanks, Nicola) so you’ll need a “speed controller” to convert your DC battery to AC pulses that can run it. The H-King 10A ESC is a fine choice for the job ($6.75).

H-KING 10A Fixed Wing Brushless Speed Controller (USA Warehouse)

You’ll need batteries to fly the thing. The 460 mah 2S packs on the left are on the light side, so you have enough lifting power for a camera as well.  ($4.44 each) The 850 mah 2S packs on the right will give you more flight time if you’re not carrying up a camera.

Turnigy nano-tech 460mah 2S 25~40C Lipo Pack (USA Warehouse)   Turnigy nano-tech 850mah 2S 25~40C Lipo Pack (USA Warehouse)

Don’t forget a charger. The Turnigy 12v 2-3S basic charger will do the job; just be sure you have 12v laying around somewhere to power it. If you don’t, the B3AC will work, although you’ve have to salvage a US power cord if you’re from around these parts.  ($4.49)

Turnigy 12v 2-3S Basic Balance Charger   HobbyKing® B3AC Compact Charger

In either case, you’re going to need something for the battery to plug in to. They use JST connectors. They’re half price if you assemble them yourself. I say, splurge. ($2.07)

Female JST battery pigtail 12cm length (10pcs/bag)  (US Warehouse)   JST Female 2 pin connector set (10pcs/set)

 

And here’s that camera. If you don’t have a fast microSD card, grab one of those too.  ($8.85)

Turnigy KeyChain Camera w/o memory card (USA Warehouse)

 

Almost done: you’ll need servos to move the wings. Just two of them, since there’s no rudder. It seems counterintuitive to have roll control but no yaw control, but trust me, it’s much more fun that way. I like the HXT500. You might want to get a spare too. ($3.64 each)

HXT500 6.2g / 0.6kg / .08sec Micro Servo (US Warehouse)
The biggest investment: your transmitter and receiver. I use a Spektrum but I think the Turnigy 5X should do just fine. It has the delta mix function you’ll need to combine your aileron and elevator channels.  Just be sure to remove the plastic case from the receiver to save weight. ($24.99)

Turnigy 5X 5Ch Mini Transmitter and Receiver (Mode 2)

 

Last but not least, I like attaching the wingtips with industrial-strength velcro so you can rip off the wingtips and throw it in a trunk or suitcase. ($1.64)

Polyester Hook & Loop Velcro V-STRONG (1mtr) (USA Warehouse)

And there you go. A lightweight, insanely powerful plane that can fold flat in your suitcase and shoot screaming aerial videos for $99.78. You’ll need to do a bit of soldering to put it together, of course. And if you don’t want to destroy your new toy immediately, you’ll want to spend an hour playing with an RC simulator (you can get a joystick here and software here or lots of other places) so you can work out orientation and stick skills in a low-impact environment.

And there you go! You’re ready to fly.

Of course, I also mentioned some more advanced RC flying, like the Techpod that I’m working on right now with reported flight times of 2-3 hours, and the FPV rig that gives you a real-time “pilot’s eye view”. I talked a bit about flying a Hobbyking Mini-Swift over Maui, HI (also a good starter plane, although not quite as crash resistant as the Bonsai and a bit harder to fly) and promised Mark I’d upload the video. Here’s a 1 min supermix of a few flights over Haleakala crater (first half) and over the coast near Kaanapali (second half).   Yeah, that’s my daughter waving at the plane flying overhead. And if you just want to see a single 3 min flight start to finish, here’s me doing a few passes over the beach at sunset.

 

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