Lawrence Hargrave

Inventor of the Box Kite?

Lawrence Hargrave is the generally accepted inventor of the box kite. His ideas were very influential in the first generation of heavier-than-air aircraft.

However, at least one kite academic has thrown in a little doubt, saying "the idea was already around."

But hey, I'm an Aussie like Hargrave and hence really like the idea of an Aussie helping to lead the way like this! At least Hargrave's writings provide a clear starting point in history for the construction and flight of cellular kites and box kites in particular.

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Hargrave's Kite-Building

Before the final perfected design, which you can see in that photo, Lawrence Hargrave went through a lot of ideas and model making. In fact, quite a number of rubber-powered flying models preceded the more well-known kite experiments!

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Going Round in Circles

Lawrence Hargrave's progression of ideas started with tubular concepts. The first such design had each cell looking like a bunch of short tubes stuffed into a single bigger tube—six smaller short tubes to be precise. A long spar connected two identical cells. Hargrave flew a paper model of this kite and was pleased with the results. Maybe it wasn't such a great lifter but at least it was very stable. The cellular kite was born!

Next, the smaller tubes were done away with, and the result was two large-diameter but short-length tubes mounted at either end of a long spar. This circular-type design is still made from time to time, by box kite enthusiasts. You could say it is like a traditional square box kite but with an infinite number of sides! And of course, it had just a single longitudinal spar instead of four.

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The Book Case Phase

There followed a rather elaborate design with many flat panels. Each cell looked rather like a bookcase with the back panel removed. Four "shelves" with vertical dividers resulted in 16 square sub-cells in both main cells. Again, a long spar joined the two cells, with a single bridle line attached to the spar. No doubt it flew, but what a complex thing to build!

With the next design after the flying book-cases :-) the appearance of the two-cell designs started to hint at the final box-kite configuration, as in the photo up there. The number of "shelves" was reduced by one, in each cell. Also, most of the vertical panels disappeared, leaving just the ones on the far left and right sides.

Now, the kite was essentially one Hargrave box-kite piggy-backing another. In other words, there were four horizontal lifting surfaces in each cell, plus the two vertical surfaces capping the wingtips. Perhaps there were some problems with the long spar bending, so a two-leg bridle was used on this kite.

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Classic Lawrence Hargrave Box Kites

From here on, several more kites were made that featured just two lifting surfaces per cell. Also, the chord (distance from front to rear edges) of the horizontal panels was extended a lot. Each of these kites looked much like the one in the photo.

Lawrence Hargrave was experimenting with proportions. He was trying hard to arrive at the most lifting ability possible, without sacrificing too much stability or adding too much weight. For example, he scaled up one version to compare its figures with a wing flown some years earlier by Otto Lilienthal. It turned out Hargrave's design had a much lower wing loading. In other words, there was less weight per unit of lifting sail area.

At this stage, Lawrence Hargrave was starting to consider how such a kite could be propelled as a free-flying aircraft. He shared his ideas freely with other experimenters and even had some influence on the inventions of the Wright brothers.

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