Engines of Our Ingenuity

No. 2508
ASYMMETRY

by John H. Lienhard

Today, dare we look upon asymmetry? The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

burning bright We all know William Blake's
Tyger, tyger, burning bright
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?

tiger glaring But why should the tiger's symmetry be fearful? Well, Blake finishes by asking who could paint that symmetry. He asks who'd dare try. He's talking about a terrible beauty -- too much for anyone to grasp or contain. Symmetry is Blake's synonym for beauty.

And why symmetry? Many psychologists suggest that bilateral facial symmetry might correlate loosely with health. Hence it's a simple marker for good mating potential. Of course, many nominally pretty faces are symmetric; but there's a catch:

Would you recognize Miss America if you met her on the street the day after you watched the contest on TV? I doubt it. More likely you'd think to yourself, "What a pretty girl," then straightaway forget her. Beauty that sticks has to violate norms. The first mistake a novice artist makes is symmetrical composition. Designers talk about balance, not symmetry. Symmetry is disquieting.

Now I don't want to talk about tigers and beauty; I want to talk about airplanes. Surely they're the most symmetric of all machines. If an airplane has two engines one goes on either wing. A third engine would have to go on the nose, right? Each wing is the same length, and so forth. Same with a bird. If it flies, it is symmetric.

And yet, many asymmetric airplanes have flown. Take, for example, the famous Lockheed Lightning -- the P-38. It was symmetric with two engines mounted on the wing. Each engine pod tapered back into a long boom that held one side of the tail. In the center of the wing was an isolated cockpit pod.

Since it was a long-range airplane, engineers decided it'd be useful to add a second pilot. So they built an asymmetric RP-38 with a second cockpit above the left engine. It worked. Not only did it fly well; it actually saw service in the Korean War.

But the Germans and Italians had gone much further in WW-II. They'd built many experimental asymmetric light bombers. They were like conventional airplanes with one wing longer than the other, and no cockpit on the fuselage. Instead, the pilots rode in a pod out on the longer wing. And they made the tail asymmetric to balance it off.

Blohm & Voss BV-141B

The Blohm & Voss BV-141B, was one of those. The Germans made almost thirty, they were quite airworthy, but they violated their pilots' aesthetics. Pilots simply couldn't accept the unbeauty of so much asymmetry. And we're back to Blake's paradoxical tiger. We need and crave asymmetry, but it's like spice on food. A little is okay; too much burns our mouths. So it is that the perfect symmetry of Blake's tiger terrifies us. But completely off-center airplanes are just as bad; and they were far more than fliers could accept.

I'm John Lienhard at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


See the Wikipedia article on Symmetry (physical attractiveness), the Geocities article on Asymmetric airplanes, and My Uncle Willie's model airplane plans for the Blohm & Voss BV-141B. See also this You-Tube of a BV-141B in flight. Color photos by. J. Lienhard. BV141B photo courtesy of Wikipedia commons.

See also Rob Zaretsky's related program on "The Beauty/Symmetry Puzzle," Episode 2340.

Listener Oscar Wehmanen has directed me to David Lloyd Rivinus' website in which are described several stunningly asymmetrical orchestra stringed instruments.


Asymmetric billboard mounting


THE TYGER (from Songs Of Experience) by William Blake
Tyger! Tyger! burning bright,
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?

In what distant deeps or skies
Burnt the fire in thine eyes?
On what wings dare he aspire?
What the hand dare seize the fire?

And what shoulder, and what art?
Could twist the sinews of thy heart?
And when thy heart began to beat,
What dread hand, and what dread feet?

What the hammer? What the chain?
In what furnace was thy brain?
What the anvil? What dread grasp
Dare its deadly terrors clasp?

When the stars threw down their spears,
And watered heaven with their tears,
Did he smile his work to see?
Did he who made the Lamb, make thee?

Tyger! Tyger! burning bright,
In the forests of the night,
What immortal hand or eye
Dare frame thy fearful symmetry?


The Engines of Our Ingenuity is Copyright © 1988-2009 by John H. Lienhard.