Bille wrote:
When Ya add camber with B and C ; it ain't worth the drag for the return.
80% is the hinge point ; so when you pull on Z at 90 to 100% , your hinge point is
still at C.
Further back than 80% hinge point, will give a higher CL change : but it's at
the expense of More drag. Most flaps on an airplane are at, or near 80% for a reason.
The relation to the % cord that each bridle is attached ,has to
do with the ratio your changing A,B and C with your mixer ; if the ratio doesn't match the % cord
then you get more drag because it introduces wrinkles to the top & bottom surface.
In other words : changing A, B and C with a mixer ,should only affect the AOA, and NOT the camber.
ONLY the Z should affect camber ; and it's best done at 80%.
Bille
All large amounts of camber are going to induce lots of drag. It's for lift that airplanes change their camber, they have big powerful engines to overcome any drag but not a significant way to increase wing area, they can extend the wing a little bit with Fowler flaps and certain LE flaps, but camber is the big changer on lift. With kites it is possible to increase projected area and camber, but it's you and your board that fights the drag.
Cambering B and C are of significant use for kites. As I said I think B has a large effect on control while still being depowered. C has a huge effect on stability. You get into the sewn profile and their is now no limit to where or how you can change camber. You can put it on the very leading edge or trailing edge or the middle. If you read a bit about peterlynn arcs and autozenith this is probably the main factor to produce that effect, I think it may have something to do with leading edge shapes.
There is seemingly a wide range of variability with what cord positions work with what mixer. If you are talking about absolute maximum L/D, where even wrinkles are an issue then very very low almost no camber or AOA is going to what you want. Of importance would be the bridles match the sewn profile. Still you could set for this , I think flysurfer may use that as a base setting where ABCZ are even, and then after it or before many very different things can happen. Like the engagement of a wac and diablo line for extreme camber after the that high L/D profile is reached.
From my limited reading what gives best L/D is near zero camber and AOA. As to what gives the highest lift is camber. For the high camber if you were to position it at the front the change would physically look much the same as just an AOA change. Gradients work well in this world and I would guess some sort of exponential curve starting very minorly at the front proceeding to massively at the end. Of course you only have 4 points on the wing to work with but still some sort of gradual curve or adjustment can be achieved. It is debatable whether foils can change AOA at all and in fact only change camber.
Have a play with
https://www.grc.nasa.gov/www/k-12/airplane/foil3.html
you will need to have java
https://java.com/en/download/ access the "configure java" through the start menu search box, under security tab, edit site list and add
https://www.grc.nasa.gov as an exemption. I have to reload the page after allowing the app in firefox. Fucking complicated and I would love to know who to blame lol.
It's not meant to be 100% accurate. But playing around with it the maximum L/D I can get is about 18.5. The wing has very little AOA and a little negative camber. Then increase AoA and the lift increases 4.5x with L/D at 6. Then increase camber a lot and reduce AOA a bit and lift goes to 10x with L/D at 3. The high camber profile looks like a hollow profile on a foil kite. Highly unstable but very powerful and won't go upwind. Despite the app only being educational, the lift changes with camber are similar to what I would say I experience, with lift about doubling when I tune for a good amount of camber. Not so sure about the negative camber having the best L/D but it may do as it's some where around flat that going upwind is the best. The camber used is quite a constant curve, and even though AOA is needed to get the lift setting to maximum with high camber, the front of wing looks like it has no or even negative AOA. Which is much how foils look like with this type of camber but with more curving to the rear of the wing depending on the mixer, settings and attachment placement,as you are trying to highlight.