Sled Kite Construction

Description

Sled Kites are suitable for most wind conditions but best in steady continuous breezes. They can be distinguished by having their canopies supported only longitudinally either with spars, air filled tubes or simply folds in the canopy material.

Design History

A Kite of this general design, with 3 spars tapering together towards the base, was patented as a 'Polymorphic Kite' by Canadian born William M. Allison in 1956. Later, a version with 3 parallel spars and a stabilising vent hole at the tail was marketed by a Frank H. Scott in the early 1960's when it acquired the now common name of Scott Sled.

Sled Kites are easy to make fly but can be vulnerable to cross-winds causing them to collapse with little or no chance of recovery. In 1979 John W. Loy filed US Patent 4279394 for a Swallowtail Kite which attempted to overcome this by having the central spar create a protruding leading edge.

Designs have continued to evolve with 2 spar versions now more common. In the early 1970's, kite designer Ed Grauel introduced the idea of vented kites and later, Sled Kites were developed with inflated canopies and spars replaced by tubes of canopy material inflated by the air pressure. Modern Foil Kites may be considered an extension of this idea.

Some general proportions and a basic method of construction is shown opposite. Experiment with Proportions, 2 or 3 Spars, Leading and Trailing Edge shapes, Vent designs and addition of Tails (you will need to press Return after each change of value).

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Note: Once you have finalised your Kite proportions and general design, the Angle of Attack can be set by adjustment of the Bridle. The normal method is to loop the Bridle over one finger and suspend the Kite upside down. The position of the finger is adjusted until the tail of the Kite hangs at an angle of 20⁰ to 30⁰ to the floor.

Once the Bridle Point has been determined in this way, loop a Bridle Line, about 8 times the length of the Spars, between the two points and attach the Flying Line to its centre.

See the DT Online article on Kite Design Basics for more information about the forces acting on a kite and how to use tails or drogues to balance them.

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Materials and Construction

Kites can be made quite successfully using thin Polyethylene sheeting (e.g. as used to make bin liners) and Adhesive Tapes, split Bamboo flower sticks. Kraft Paper can also be used and even Tissue Paper, especially for smaller Kites and using BBQ Skewers for Spars.

More sophisticated Kites, and most commercially available Kites, use Ripstop Nylon or similar, together with Fibreglass Rods and Tubes. Instead of fixing with tape, extra allowances are added to the Kite pattern where needed, to enable the Spars to be slotted into sewn hems.

See the DT Online article on Basic Kite Construction for more detail.

Designer

• Click on the pencil-shaped Edit icon below to show or hide variables and click inside table to alter values (scroll to see all).
• Left or Right click on the screen display or use Scroll Wheel to alter view and Left click on Zoom icon to restore (note: Zoom will be focussed around the cursor position)
• Left click on Download icon and Open with your preferred browser then print screen image from there (useful for trying ideas for text and graphics etc. but unlikely to be actual size), or Save File to create a full-size Scalable Vector Graphics (svg) file which can be loaded into LibreOffice Draw and printed, or graphics software such as Inkscape for eventual output at actual size to a Plotter/Cutter for example. See Packaging Designer User Guide for more detail.

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Note:

• The main variable in the table below is the total length of the Kite Spar (set initially to 1200mm).
• Almost all other dimensions are derived as a Percentage of the Spar Length (e.g the total Width, the variable <MaxWidthPercent>, is set initially as equal to the variable <SparLength> - or 100%).
• Parallel Spars are generated by setting the variable <BottomWidthPercent> to be equal to <TopWidthPercent>.
• Note that either numbers or <variable names> may be typed in to alter kite proportions.
• You will need to press Return after each change of value.
• All Percentages initially are based on the proportions given at the start of this article but all can be changed by clicking in the table and typing in a new Percentage (e.g. the Leading Edge can be straightened by setting the variable <BridleTopPercent> to zero or made pointed by setting to a minus number).
• Refreshing or reloading the page will reset all variables to their default values..

See Packaging Designer User Guide for further information.

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Sled Kite Examples

• William M. Allison's 1956 Flexible Kite patent, US2737360, (aka the (original) Sled Kite).
• See below a home-built14ft "'Scott Sled"' kite made from clear polyethylene sheeting reinforced with Duct Tape and 2" x !" softwood Spars.
• A range of commercially produced Sled Kites are available from Amazon.
• US Patent 4279394 for a Swallowtail Kite filed in 1979 by John W. Loy.

William M. Allison's 1956 Flexible Kite patent

Home-built Scott Sled Kite

Sparless Sled KItes

1979 Patent Swallowtail Sled Kite

DT Online Buyers' Guide

Bamboo Garden Canes	Split Canes	Fibreglass Roman Blind Rod	Clear PVC Tubing	Nylon Ripstop Fabric	Mixed Coloured Tissue Paper	Gaffer Tape Coloured	Coloured Polythene Dust Sheets	Flying Kite Line	Kite Workshop Handbook