Droneball - Tennis With Drones

What is Droneball?

Drone racing too mainstream? Well try out this new sport called Droneball! The goal is simple, drones fire balls at each other, if your opponent fails to hit the ball or it goes out, you win. Droneball can be played outdoor on a tennis court, or indoor in a badminton court.

How Does It Work?

I'll immediately give a disclaimer that I have personally tried this, and it makes the drone VERY hard to fly! I actually crashed my drone whilst warming up for the game! Even for lightweight badminton rackets, you'll probably need a heavy lift octocopter to control it effectively. 

Firing lightweight balls is not really a matter of hitting hard, but rather hitting fast. So I designed a system where the badminton racket gets swung by a servo. The part that gets attached to the servo is shown below:

Its just a horn connected to a custom pipe clamp with a hole size of 6.5mm. I used aluminum stock that was available to me, but the one shown on the picture is massively oversized. Best type of stock is a bar thicker than 5mm, this gives plenty of grip surface. Recommended width is 10-15mm. I use a plastic servo horn here, but they are simply not fit for the task, they are far too flimsy. Invest in an aluminum servo horn. 

Get some cheap second hand badminton rackets and chop the grip section of the handle off.

Here I tried to maximize the length of the boom to get the most speed. I was being too greedy here, probably contributed to the demise of my drone.

The other half of the effort goes into making servo brackets. To make nice square cutouts on those backets, use a fairly large drill bit and drill a hole or two at the corner of the cutout, so that the hacksaw blade is wide enough to make a perpendicular cut. Of course you'll need to make another slice as shown in the picture below to get the blade in.

A file makes quick work in getting the final shape.

The Result

Take a look for yourself:

Not 100% sure what happened. But I believe it was a combination of the badminton racket acting as a large drag surface, CoG shift, reaction torques and the fact that the drone was accidentally put into alt-hold mode despite having such poor control authority led to the drone's demise. If anyone has better hypotheses, put a comment below.

May revisit this idea with air guns to avoid problems with high drag, CoG shifts and reaction torques.