< en français >.
Author : Glenn Davison. the book, “Kites in the Classroom.”
The
bridle is the line which runs fore to aft of the kite, to which the
flying line is attached. The point at which the flying line is attached
to the bridle is called the towing point.
The towing point is probably the most critical part of the entire kite
in as much as, if it is wrongly situated, even the most perfectly
designed and constructed airframe won't get off the ground. The towing
point and bridle perform the important function of establishing the
kite's correct flight attitude, or angle of attack.
Without
exception Hargrave flew his box kites without bridles, the flying line
always being attached directly to the face of the kite. The normal fore
to aft bridle is referred to as a two-legged bridle, and there are no rules concerning how many legs a bridle need have.
Usually the configuration of the kite decrees its bridling technique, and this may range from one-legged bridle, so to speak, as used by Hargrave, to a hundred or more. The many lines that make up a multiple bridle are referred to not as legs but as shroud lines, though what quantity of legs are needed before they become shrouds doesn't appear to have been defined. The object of a multi-legged or shrouded bridle is not simply to hold the kite at its most efficient angle of attack, it also distributes stress evenly throughout the structure of kite, helping it to retain its configuration under high wind velocity.
The accepted average setting for a bridle is arrived at by laying the kite upon its back, and, having attached the bridle line to the bridling point fore and aft of the spine, lifting the top end of the kite by suspending the bridle loop over one finger. By manoeuvring the line until the tail end of the kite is at an angle of between 20° and 30° from the floor (i.e. below the horizontal) the point on the bridle at which the kite now balances at this angle should be established. A towing ring should then be attached to this point by means of a lark's head hitch. Normally the towing point should be situated approximately one third down the length of the spine, and should stand away from the kite face about one half the total length of the spine. When the towing point is correctly situated the kite should rise sharply and straight when pulled forward and should require only minimal re-setting at the flying site in order to trim the angle to the prevailing wind-speed.
The basic rule in bridle adjustment is : low wind-speed - high angle; high wind-speed - low angle. In other words, in a low wind-speed a greater angle of attack is needed than in a high wind-speed. By exposing a larger area to light breeze more wind is deflected over the face of the kite, at least at launching attitudes, helping it to pull against until it reaches (hopefully) more lively air higher up. In a high wind velocity there is a good chance that the pressure of the air upon a surface set at too great an angle will break the spars before the kite leaves the ground; though if it's sturdily made and becomes airborne it will be unstable as the wind pressure will override the stabilizing system, whether a tail, cells, fins or whatever.
Usually the configuration of the kite decrees its bridling technique, and this may range from one-legged bridle, so to speak, as used by Hargrave, to a hundred or more. The many lines that make up a multiple bridle are referred to not as legs but as shroud lines, though what quantity of legs are needed before they become shrouds doesn't appear to have been defined. The object of a multi-legged or shrouded bridle is not simply to hold the kite at its most efficient angle of attack, it also distributes stress evenly throughout the structure of kite, helping it to retain its configuration under high wind velocity.
The accepted average setting for a bridle is arrived at by laying the kite upon its back, and, having attached the bridle line to the bridling point fore and aft of the spine, lifting the top end of the kite by suspending the bridle loop over one finger. By manoeuvring the line until the tail end of the kite is at an angle of between 20° and 30° from the floor (i.e. below the horizontal) the point on the bridle at which the kite now balances at this angle should be established. A towing ring should then be attached to this point by means of a lark's head hitch. Normally the towing point should be situated approximately one third down the length of the spine, and should stand away from the kite face about one half the total length of the spine. When the towing point is correctly situated the kite should rise sharply and straight when pulled forward and should require only minimal re-setting at the flying site in order to trim the angle to the prevailing wind-speed.
The basic rule in bridle adjustment is : low wind-speed - high angle; high wind-speed - low angle. In other words, in a low wind-speed a greater angle of attack is needed than in a high wind-speed. By exposing a larger area to light breeze more wind is deflected over the face of the kite, at least at launching attitudes, helping it to pull against until it reaches (hopefully) more lively air higher up. In a high wind velocity there is a good chance that the pressure of the air upon a surface set at too great an angle will break the spars before the kite leaves the ground; though if it's sturdily made and becomes airborne it will be unstable as the wind pressure will override the stabilizing system, whether a tail, cells, fins or whatever.
Herculean strength will be needed to hold a large kite if it does get
into the air, and if it doesn't suffer a line break it will very
possibly go into a series of tight lateral spins before crashing badly. A
low angle of attack eliminates this by allowing greater air spillage
around the kite, and with reduced pressure upon its face the stabilizers
have a chance to take effect.
1. two-legged bridle
2. three-legged bridle
3. four-legged bridle
4. compound bridle
5. box kite flown on edge with a two-legged bridle
6. box kite flown flat with a four-legged bridle
7. front view of a multiple bridle on a multi-finned bow kite
8. the same multiple bridle (nine shroud lines) seen from the side
