The Box Kite: History, How they Work, Spectacular Designs
Box kites haven't been around for as long as many people think, The Chinese were using single sail kites 2.800 years ago. The box kite though, was only invented about one hundred years ago by an Australian called Lawrence Hargrave. He wanted to use them for manned flight and managed to get about 16 feet into the air by using a series of linked kites.
The way that box kites are made means they can be very light, rigid and strong. Each sail supports the other.
The extra wing surface of the design gives more lift than a single-sail kite and most altitude flying records are held by box kites.
They have had a big impact on history. The Wright Brothers were influenced by the box kite in their design of the first powered, manned plane. Recently, a better understanding of aerodynamics has allowed some very exotic machines to fly with strong echoes of this very simple technology.
Uses of Box Kites
Collecting Weather Data
The kite pictured below, was designed by H.H. Clayton, of the Blue Hill Observatory, Boston, USA in the 1890's.
It could carry weather instruments to a height of 9,200 feet which is nearly two miles!
Such successful, easy-to-fly designs, caught the public imagination and made box kites one of the sensations of the age.
Wild West showman, Samuel Franklin Cody from Davenport, USA, developed a large kite that had enough lift to carry a basket with human passengers.
The British used his design to direct artillery fire during World War One.
Some enthusiasts still build and fly Cody Kites, as you can see in the video below.
Box Kite Aircraft
The astonishing heights achieved by box kites and the tremendous lift that they could produce excited many early aircraft designers.
Pioneers like Voisin, Bleriot and the Wright Brothers all experimented with box kite-inspired flying machines.
Annular wings (round rather than square) have also been developed.
As everyone knows, the first successful, heavier-than-air, powered flight came courtesy of the Wright Brothers, in 1903. Their machine is pictured below, and shows how strongly they were influenced by box kite design.
Struts were used to separate the wings and wires kept the wings rigid. This allowed very lightweight materials to be used throughout.
If you compare the Cody Kite and the Wright biplane, you will see how similar they are.
Box Kites for Fun
Although the box kite was originally developed for serious purposes, it soon became a favorite of children and grown ups around the world.
By the late 19th Century, designs were appearing in books aimed at families who like to build their own playthings.
Below is an illustration from a woodworking manual in a series called the 'Children's Library' of the late Victorian era. It shows how to make a box kite according to the latest 'scientific design'.
You can find the book by a simple search of Project Gutenberg.
How does a Kite Work?
The kite flies in amost exactly the same way that an aircraft flies. The difference is that an aircraft's engines force it through the air but a kite is tied and held still while air (wind) rushes over it.
When air flows over an aircraft wing or a kite surface, it will flow more quickly over one surface then the other.The difference in air speed between the upper and lower surface means there will be a pressure difference and this means lift. The picture explains it better than words!
If you want to understand how all the forces in a kite work, this page from NASA will tell you: http://www.grc.nasa.gov/WWW/K-12/airplane/kitefor.html
How do You Make a Box Kite?
You need light, rigid struts and a material that won't stretch too much even if it gets wet. This meant bamboo and silk for early Chinese single surface kites.
Nowadays, there are space age materials that are super strong and light like Dacron and carbon fiber struts. This means ever better performances from all kinds of kites. There are even radio controlled kites available!
The video below shows you how to assemble one kind of box kite.
It is possible to design all kinds of kites with the basic box kite structure. The spectacular kite pictured above, with six ring-like sails, is typical of the new breed of box kites.
The video below shows a twisted box kite which has a spectacular appearance in the air.
Kite Fairs Conventions and Meetings.
One of the biggest kite fairs in the world is held every year at Long Beach in Washington State. Other festivals around the world can be found here:
Lincoln City Kite Festival
The Pacific Coast also offers the Lincoln City Kite Festical, Why is the Pacific coast so blessed with festivals? The wind off the pacific is usually steady and true as well as strong enough to make it one of the best areas to fly a kite in the world.
Interactive Kite Modeller Program
NASA offer a page where you can design your own kite and see how it performs http://www.grc.nasa.gov/WWW/K-12/airplane/kiteprog.html