A certain manufacturer discusses this in a recent video, and uses the terms incorrectly.

It doesn't really matter in the scheme of things, but it does display a certain ignorance of what is happening when a kite flies.

I am wondering if you guys know the difference?

who the hell was he talking to?
en.wikipedia.org/wiki/Angle_of_incidence(aerodynamics)
so basicly its the angle the kite is designed to fly at

not the angle the kite IS flying at (via changeing the AoA trimming etc etc)



bit off topic but that weird thing in the pool where your friends got no body just a head and some legs or whatever due to the refraction of light ....i think... the measurable amount of that angle is called an incidence ... intresting

Index of Refraction for Vacuumn = 1.00Refractive Indices for some common GasesGasRefractive Index
- n -Acetone1.001090Air1.000293Alcohol, ethyl1.000878Alcohol, methyl1.000586Ammonia1.000376Argon1.000281Benzene1.001762Bromine1.001132Carbon dioxide1.000449Carbon disulphide1.001481Carbon monoxide1.000338Chlorine1.000773Chloroform1.001450Ether, ethyl1.001533Ether, methyl1.000891Helium1.000035Hydrochloric acid1.000447Hydrogen1.000132Methane1.000444Nitric oxide1.000297Nitrogen1.000298Nitrous oxide1.000516Oxygen1.000271Pentane1.000686Sulphur dioxide1.000686Water vapor1.000261Index of Refraction for common Liquids
<div class="center">FluidRefractive Index
- n -Acetic Acid1.37Acetone1.36Alcohol, ethyl (ethanol)1.36Alcohol, methyl (methanol)1.33Alcohol, propyl1.38Aniline1.586Benzene1.501Benzyl benzoate1.568Carbon disulfide1.63Carbon tetrachloride1.46Chlorobenzene1.525Chloroform1.44Decane1.41Dodecane1.41Ether1.35Ethylene glycol1.43Ethyl salicylate1.523Ethyl cinnamate1.559Trichlorofluoromethane refrigerant R-111.37Dichlorodifluoromethanerefrigerant R-121.29Chlorodifluoromethane refrigerant R-221.26Furan1.47Glyserine (Glycerol)1.47Heptane1.38Hexane1.37Methyl salicylate1.538Methylene iodine1.737Milk1.35Octane1.40Oil, cedar1.516Oil, vegetable 50oC1.47Oil, oiive1.46Oil, turpentine1.47Paraldehyde1.405Parafin, liquid1.48Propane1.34Propylene1.36Propylene glycol1.43Quinoline1.627Toluene1.497Turpentine (wood)1.47Water1.333
Example - Speed of Light in AirThe speed of light in air can be calculated asv = (299792458 m/s) / 1.000293
= 299704645 m/sExample - Speed of Light in WaterThe approximate speed of light in water can be calculated asv = (3 108 m/s) / 1.33 = 2.26 108 m/s

those numbers are basicly just the angle at which light refracts thru the material.

so if you swap light for kite we can imagine its angle going thru the air

all this is pretty pointless much easier to just say angle of incedence is whatever the angle is that the kite flys at 100% as its pasing thru air

gorgo? am i right or wrong or halfway there? the diagram on the wiki link makes it pretty clear

en.wikipedia.org/wiki/Angle_of_incidence(aerodynamics)#/media/File:Aircraft_Angle_of_Incidence_(improved)--1080x660--25Mar2009.jpg

Kozzie said..
who the hell was he talking to?

en.wikipedia.org/wiki/Angle_of_incidence(aerodynamics)

so basicly its the angle the kite is designed to fly at

not the angle the kite IS flying at (via changeing the AoA trimming etc etc)



...

Basically correct in principle, although the language is a bit clumsy and the bit in brackets is wrong in both cases (except the "etc etc" which is correct), thus giving an actually incorrect answer.

Hey Peeps,

My understanding of the two, from doing an apprenticeship as an Aircraft Maintenance Engineer, (way back in the day ) is that the Angle of incidence is the angle of the wing chord in relation to the line of the longitudinal axis of the fuselage of an aircraft when flying in straight and level flight. Not really relative to kites.

The Angle of attack is the angle of chord line of the wing in relation to the direction of movement into the relative wind. This is variable by pitching the aircraft with the elevators or by sheeting in or out with the bar on a kite. This is applicable to kiting and aircraft.

Simples! IMHO

DM

Gorgo said..
Correct .. mostly.

Yes the angle of incidence is the fixed angle between the wing chord and the fuselage. A kite doesn't have a fuselage,

The critical difference is the lack of a fuselage and the fixed angle of an aeroplanes's wings relative to its fuselage.

Gorgo said..
but the principle is the same so you would need to use an imaginary fixed line to represent the fuselage. When you think about it, the wing chord is also imaginary. On just about all modern wings the chord changes throughout the span so you'd have to work on the average chord or the chord at the centre of the wing.

No offence meant, but this is all imaginary.

Gorgo said..
The AoI changes depending on the attachment knots you use when you rig up, the trim strap adjustment, or the bar position in and out. It's a relatively simple physical thing, and it's the thing you change when you are controlling your kite.

But in the next paragraph you are saying that the the shortening or lengthening of the front and rear lines relative to each other is changing the AOA. So I think its all AOA, there is no AOI with a kite, because it is a kite, not an aeroplane.

Gorgo said..
Also yes, the Angle of Attack is the angle relative to the apparent wind and it is variable. Thing is, on a kite it is massively variable and changes depending on the AoI (trim, knots, bar position, kite design), plus the speed of the board, the strength of the wind, the amount of edging you do, the speed and position of the kite through the window, the direction you're riding relative to the wind and the current position of the kite. All of these affect the AoA and the AoA is changing constantly.

This is the difference, by varying the line lengths relative to each other, a kite is always changing its AOA in real or apparent wind. An aeroplane has a fixed AOI whether it is sitting on the ground stationary, or on a runway and also stationary pointing into a 20 knot headwind, and when it is flying.

Gorgo said..
People talk about depowering the kite. Some talk about tuning bar position. Others talk about changing the angle of attack. Others just ride around and wonder why their kite falls out of the sky when they're going for maximum power.

Yes that is a very inaccurate term for what is happening, they are trimming the kite, trimming its AOA. Or trimming the bar position relative to their body for comfort and performance.

Gorgo said..
Better riders understand the exact nature of trim and air speed and power and the various angles. Arguably the best riders just feel it intuitively. That is why a good rider can blast around fully powered on a 6-7-8m kite while others are struggling to get going with a 12-14m kite.

BTW The same thing applies to the board and the water, except you can see the nose sticking up in the air.

Yep some riders and kiters are just naturals, I find kids often have this "6th sense" in spades. And these things (AOA and AOI) apply to a hydrofoil too

Angle of attack is dependent on whether I am on my knees, missionary or on my back. Angle of incidence is when I'm sleeping.