Planes don't always have to be symmetrical. Here are some aircraft that go against the grain.
I love unusual looking aircraft. There's something quite special about a design that looks completely unlike anything else. One good place to look to almost guarantee the discovery of some wacky concepts is within the world of asymmetrical airplanes. Although most planes are symmetrical, with both sides being mirror images of each other, there's actually no fundamental reason why they should be.
A Brief History Lesson
When you look back into the mists of time, you'll find that many of our perceptions of what's 'normal' when it comes to aircraft design are shot clean out of the water. History is full of radical departures from the norm. However, far be it that these departures are just mere anomalies along the evolutionary timeline of aviation - many were successful concepts that simply got left behind in favour of more conventional designs.
You might also think that these unconventional designs really only make up a smattering of examples throughout the twentieth century. Yet, even if you look at the very first example of manned powered flight, you'll notice that the Wright Brother's Wright Flyer is actually somewhat asymmetrical. It had an offset arrangement of the pilot and engine on the centre section of the lower wing.
Often asymmetry was used to counteract problematic characteristics. The World War Two Italian Macchi C.202 had an offset fuselage and one wing slightly longer than the other. This was to counteract the troublesome torque effect that came with putting relatively large engines in small fighter airframes.
A more obvious example of an asymmetrical aircraft is the German Blohm and Voss BV 141. This plane was designed to be extremely good at its job as an observational aircraft. Here asymmetry was used as a feature rather than a fix.
Asymmetry on a Smaller Scale
So you'd probably think, 'doing asymmetry on a smaller scale would be pretty hard', and you'd be mostly right. Despite this, though, some people have managed it rather well. Terry Dunn, for example, created this extraordinary design called the Parallax. 
In terms of how the thing works, it's all about balance. Specifically, lateral balance needs to be spot on in order to fly just like any other plane. This axis can be found running parallel to the motor fuselage section. Check out this article on acting forces.
If you want to design your own oddity of an airplane, Terry has boiled it down to three core principals on his RC Groups Parallax thread. Firstly, the centreline can be found by finding the point at which there the wing area on both sides is the same, discounting areas covered with a fuselage or motor pod as you might imagine. Secondly, if the motor is offset from this central point of lateral stability, it's not so much of a big deal, but just make sure it's not too far away or else you'll be flying in circles. Thirdly, drag from unevenly distributed surfaces (the fuselage pod etc) are not much of an issue so can be pretty much ignored! It's all about balancing those forces, but if the items affecting those forces are negligible then they're not really worth worrying about. Just try to find that sweet equilibrium.
Terry also designed this variation of his Parallax design. The Yin-Yang features two motors, one as a pusher and the other as a tractor. With this straight wing and dual motor setup, it's slightly easier to get your head around how the thing actually works.
Many thanks to Terry Dunn and Lee Ray for supplying the superb images of Terry's Parallax and Yin-Yang designs. You can check out more of Terry's work on his website.
Links
Article and plans in Model Aviation
Link to the RC Roundtable Podcast
Article by James Whomsley
Editor of FliteTest.com
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