One of the current trends among micro-quadcopter enthusiasts involves modifications that purposely keep their flying machines at ground level. This floor-hugging tweak is called the Tiny Whoov. It is a micro RC hovercraft built around the uber-popular Blade Inductrix quadcopter.

There are several different ways to get a Tiny Whoov of your own. A cursory web search reveals many step-by-step tutorials, a few manufactured conversion kits, and even an off-the-shelf hovercraft from Blade, the Inductrix Switch. All of the links I found are based on the Inductrix (or one of the many clones).

I wanted to build a Tiny Whoov, but I still enjoying flying my Inductrix in stock form. So I wasn't keen on clipping its wings. Undeterred, I decided build my own variation on the quadcopter-to-hovercraft theme using a different micro-quad. I improvised a simple design while taking copious inspiration from the Tiny Whoov.

Build Notes

The Tiny Whoov uses only the front two rotors as lift fans for the hovercraft. The rear rotors are used to propel and steer the vehicle via differential thrust. With this setup, the same control and gyro settings that work as a quadrotor will also work in hovercraft mode…sort of. More on that later.

The heart of this hovercraft project is a 1SQ mini-quad from Heli-Max.

For the quadcopter, I used my venerable Heli-Max 1SQ. You may recognize it from my recent Christmas tree drone. Although I didn't know it at first, the modular construction of the 1SQ made it ideal for this project. But don't worry if there isn't a 1SQ on your shelf. The basic components of most mini-quads are the same. I suspect that you can crank out a similar hovercraft with whatever quad you have on hand.

There is nothing fancy about the design or materials that I used. Most of the hovercraft hull was constructed with cheap foamboard and hot glue. One sheet of foamboard from the dollar store is adequate to build several of these things.

It's been nearly four years since I reviewed the Kyosho Blizzard SR, an electric-powered RC snowcat. I wrote that review in summertime while visiting family in Florida. Although designed for snow, the Blizzard adapted well to the loose, sandy, foot-scalding soil. Now that I live in Buffalo, NY, I've been able to operate the Blizzard in its natural habitat. It is an amazing little machine that thrives in the snow. The stock controls, however, needed a few updates to make this machine more user-friendly in freezing temperatures.

Baby, You'll Freeze Out There

One of the selling points of the Blizzard SR is that it uses a Wi-Fi link with your smartphone for control. Kyosho's iReceiver app provides on-screen thumb controls to operate the tracks. It also shows a real-time video feed from a forward-facing camera in the Blizzard's cab. The end result is First Person View (FPV) RC snow plowing.

I noted in the review that the phone-based controls worked well enough most of the time. However, the connection was not completely reliable. Also, the driving controls were somewhat clunky without the tactile feedback of a standard RC controller. More recently, I discovered that the phone interface has other limitations when driving in cold weather.

Most modern, electric-powered RC airplanes utilize brushless motors for propulsion. And why not? Brushless motors are much more efficient than their brushed cousins (not to mention lighter and sometimes even less expensive). Similarly, airplane models that were designed to use brushed motors can enjoy a huge boost in performance with an upgrade to brushless power.

Some brushed-to-brushless upgrade projects are just a simple matter of swapping out the relevant components (motor, Electronic Speed Control (ESC), propeller). Others require a bit more planning and modification. My most recent brushless upgrade is a good example of the more-complex type. I'll show you the hurdles I encountered during this project and how I cleared them.

The Airplane

The recipient of this power system transplant is a small electric sailplane called the Skimmer 400. Kits for this balsa airplane were popular during the late 1990s and early 2000s. Like other electric-powered models of that era, the Skimmer 400 was designed around the brushed "can" motors and NiCad batteries of the day. There was never a surplus of power with that gear. So models that performed well, did so by virtue of excellent airframe design. I've found that these types of model airplanes adapt particularly well to brushless upgrades.

My Skimmer appears to have led a hard-knock life. I bought the airframe in very-used condition at a recent RC event. Despite model's wrinkled and tattered covering, the balsa structure seemed to be built relatively well and I did not notice any obvious crash damage. It may be an ugly duckling, but the asking price was only $5. What was I supposed to do…just leave it there?

This old Skimmer 400 looks rough, but it performs really well with a modern brushless motor.

As originally designed, the Skimmer 400 was powered with a Speed 400 brushed motor spinning a 6-inch propeller. "Speed 400" is just an RC-centric term for the generic Mabuchi RS-380 motor that is used in all types of different applications around the world. It has a diameter of 28mm (1.1"), is 38mm (1.5") long, and weighs 65 grams (2.3 ounces). The intended battery pack for the Skimmer 400 consists of seven 2/3A-sized NiCad cells of 600mAh capacity. Altogether, this system produced about 60-80 watts of power…enough to fly the Skimmer 400 in a leisurely fashion.