Sorting kite arches by wind-direction dependence
- Kite arches relative to wind-direction dependence:1. Dependent2. Non-dependent (omnidirectional ?)The kite arches dependent on wind direction may concern with site issues, anchor-movement issues, overspeed protection (OSP) issues. Static-positioned anchors and mobile-positioned anchors provide special concerns.The non-wind-direction-dependent arches may concern with tangle issues, control issues, and OSP issues.Merits and challenges within each category of kite arches sorted by dependence or independence of wind direction for AWES applications may be explored.
- We can say definitively that a normal arch must rotate to follow major change in wind direction (greater than common veering of about 90deg.). Decorative festival arches are easily turned by dragging their sandbag anchors about. Mothra1 has a belaying-winch cableway on one side to turn it, and this worked, but we hardly used or needed it. Many wind shifts are best accommodated by slacking the windward anchor. The surprise method we discovered was to land the arch (very easy by design), unshackle it, roll it up from both ends into the "Torah Scroll", rotate-in-place the rolled-up kite, then unroll it to its new orientation, shackle to new anchors, and relaunch (again very easy). The whole process only took a couple of minutes for the 300m2 arch, and was very safe and manageable, avoiding high actuation force and obviating the capital equipment to handle high force.
The term "Kite Dome" has been proposed for omnidirectional "arched" kites that accept wind from any quarter. They are distinct from single-arches, as they have a radial cupped geometry and a minimum of three anchors. The main design trick is to support whichever is the upwind lip or lips from luffing, using standard solutions. A nice refinement will be kixels rigged to tilt into trim position by common array drawlines, without having to tilt the whole dome
- "Normal arch" seems to be applicable to those kite arches that fix wing elements generally parallel to the main arch load path."Dome" kite arches seem to the beginning of "second floor" arrangements where the new floor becomes a place for attaching aerial anchors of other flying elements.Pause on a "non-normal" and "non-Dome" and just two-anchor omnidirectional fairly-easy kite arch that needs no anchor movements at terra firma when wind changes about the frull wind rose: The key regards flying-unit lead lines. Stake out two spread anchors; have a load-path arch line longer than the straight distance between the two spread anchors. At mid arch line attach, say 10 separated single-wing-sub-kite systems with a non-tangle spread schedule along the main arch load-path line. Let the wings fly. See the main arch line rise. Let the wind rotate during the hours to all points of the wind rose. The arch will stay aerial; the sub kite systems will stay flying. The two anchors of the load path need not be altered. As this kind of arch kite system is not seen much, it is not mathematically "normal" in the population of kite systems; but it has a regular right to survive in the kite culture. I've looked for images of examples of such two-fixed-anchor omnidirectional kite arch, but is is not new, except its description is hard to find. Pausing here might help the sparse attention on it. Such a system is an constructive element of some "Dome" arrays or meshes. DaveS has mentioned "leader lines" in some text that is close to this matter. But the prior post insistence on three anchors is stressing me to have this pause comment and description. The trivial omnidirectional two-fixed-anchor system is the single-line kite whose tether bifurcates to two spread anchors; the anchors need not be moved when the wind changes to any direction; such load-path line looks more like a triangle than an arch; just add more single-line kites to the load-path line to get the "polygonal" arch (term used by DaveS and Rod Read) for cousin matters. DaveS points out the tangle prcept which would play on the scheduled distance apart of the roots of the single-line sub kite units placed on the omnidirectional arching load-path doming line; two anchors suffice and they can be fixed; let the wind blow from any direction ... and still no need to change the position of the anchors.I have proposed an earth-surrounding load-path line with one line to soil that goes up to a circle line that goes around the earth to which are connected single-line kite sub units. The net common west to east flows will on average sometimes permit the earth to be so surrounded. Until that is achieved, what records might be achieved for two-fixed-anchor kite arches holding those leader-lined sub-kite units set apart enough not to tangle with each other? Who will reach the 10 km achor-spread first? The 100 km anchor spread? The 1000 km anchor spread? The Los Angeles to Delaware anchor spread? And what "AWEifications" might climb aboard the "two-fixed anchor omnidirectional kite arch systems" ?
- Here is a non-self drawing just found:
- But that author apparently did not appreciate that he did not have to instruct "perpendicular to the wind" for anchor set.
His caption note:
"Tether Anchor: One final option is to anchor a strong line perpendicular to the wind and then attach several kites into this "tether" with shorter lines. This is another way to maximize the amount of sail you fly in a limited space. Increased safety is another benefit."
The "perpendicular" to wind was unnecessary restraint. The wind may change to any direction and the anchors need not be changed.
His drawing looks like the spread was not enough to prevent tangle. But that could be fixed.
--- In AirborneWindEnergy@yahoogroups.com, "Joe Faust" <joefaust333@...> wrote:
> Here is a non-self drawing just found:
- Wind-direction-dependent kite arches of the ribbon sort come in two main variety:Flip-wing (rotating ribbon)andNon-rotating.Here is a non-rotating ribbon arch kite wind-direction dependent kite arch example:When such a "ribbon" is segmented, we get "normal" kite arches with left-right spar lined with load-path.Here is a rotating ribbon wind-direction dependent kite arch:Move one achor if the wind changes enough.These matters are to show contrast with the fixed-two-anchor wind-omnidirectional kite arch described in above post where wing left-right spar sense need not be parallel with the main arch load-path.
This is a fantastic design space; not exactly what we mean by AWE, but suddenly we know how to build almost anything across the sky, "cheap, fast, and in-control", so long as the wind blows.
Your original sketch for this thread did show the trains set very close along the arch loadpath, but its true that the arch line could be tens of kilometers, and the trains well separated. You are saying that any kind of spider-work fixed in the sky can be kept up by trains that fly regardless of wind direction. Trains allow greater lift than single unit kites, so its a scalable method. How about classing it as a "lifter-train" method? As suggested, one can also put single lifters on leaders all over a string loadpath network. Ed has been flying this sort of arch in Austin lately, as training.
So any sort of arch, dome, or matrix can be lifted by distributed lifters, which do all the required rotating with wind direction. Lets not forget to consider dynamic anchor fields as a sort of many legged mirror world. Could we make giant tumbling structures even? It seems so, if one masters the magic hidden in "rag and string".
What delightful madness, to imagine the infinite possibilities of combining all known kite methods 8^)
- A few more arch possibilitiesAn arch could be flown on top of the spread spar ends of a Makani style kite ... thus you can fly an arch with a single ground tether.orShort lifting kite trains between layers of arching, are set on a swivel spar top and bottom. As long as the arch is launched top first, always pulling lower levels upward... This keeps the trains taught and able to follow the wind.I know we tend toward avoiding "spar" as it suggests rigid weight, but we can't deny their use. Sparred kites are less prone to collapse in sudden changes of direction.Assume a swivel mounted tether bifurcates to attach onto two ends of one spar... can the tether still continue up through the skin of lifting ram air kites? then attach onto a top spar ends, then rejoin at a top tether....? This way the tethers are kept spread for stability, the kites cant tangle, you can follow any wind change...Instead of going through the kite why not use an inner web as a tether attachment top and bottom avoiding piercing and internal pressure loss...It's usually mixes of tech elements which brings the greatest changes