1853 Cayley Improved Riding Rudder Glider Model

Click on the image to download a 1000 pixel wide image.

In 1853, Sir George Cayley wrote a paper for "Bulletin Trimestriel", a French aeronautical journal, and included the following description of a large model glider. Unfortunately the journal folded before Sir George's paper could be published. The extract has been slightly abridged for this website. 

"As many persons are incredulous respecting the possibilty of aerial navigation by mechanical means, it might increase public confidence were one to show, in action, the perfect balance and steerage that the cheap and simple apparatus shown here can exhibit. 

The sail is 6 feet 2 inches long, by 4 feet 3 inches wide - sewn on to flat oval yards, 6 ft 2 inches long, and elevated 1 foot 4 inches above a shaft 12 1/2 feet long. The horizontal rudder which gives the balance, contains 6 square feet of surface, and the separate upright rudder, for side steerage, contains 2 square feet.

There is a curved prow of iron to ease the shock when it alights on the ground and this weight, being screwed to the shaft, at a greater or less distance for the center of support, B, enables the centre of gravity, G, to be placed as much in advance of that point, as its found requisite to give the proper inclination for the descent of this sort of parachute. The whole apparatus weights 16 pounds. It requires no minute description: and will be best understood by viewing the drawing.

When used, it is projected by hand from the edge of a hill or lofty building: and will fly from 4 to 8 times horizontally the height of its perpendicular fall, according to the correctness of its adjustment. 

The horizontal rudder gives the most stability to the course of flight, when slightly evelated, so as to receive a small degree of pressure downwards: but when truly balanced by the weight of the prow, it flies the farthest, when the rudder is in the same plane as the sail. The side steerage, by the small separate upright rudder, is always perfect, when other adjustments are complete."

Note that the wing of the glider is simply cloth stretched over two spars, front and rear. There are no wing ribs.

In addition to the above extract, Sir George Cayley also wrote up a description of the glider in one of his notebooks, but gave that model slightly different measurements. The notebook description is important as it supplies two new pieces of information.

One is that the Centre of Gravity is specified. Cayley wrote the glider was balanced when the wing was "divided in the ratio of 18.5 inches to 35.5 inches" which is 34% of the chord.

The other detail is that the parasol wings of the glider had a small measure of anhedral created by the tension in the bracing cords. Note that the two illustrations show different arrangements for the bracing cords.

The table below gives the main dimensions from the two sources.

The source of this material is the book "Sir George Cayley's Aeronautics 1796-1855" by Charles Gibbs-Smith, published by Her Majesty's Stationery Office, London, UK, in 1962. Copies of the book may be found at www.bookfinder.com.

email aerohydro