I have to say, RevPaul let me try out his Pansh Sprint and the little bugger shocked me at the power it had for such a noodle of a kite. Thing is, I
think all race kites are "noodly" like that......long and skinny I mean, aren't they? So I've been trying to figure out, what the heck is it that
makes that thing (and likely most other race kites) so darn powerful?
Really I'm just curious, no real urgency on the answer as I'm sure it's not just a simple five word answer. If someone in the know can find the time
to illuminate me though it'd be appreciated.awindofchange - 22-9-2008 at 04:47 PM
It's cuz it says...RACE... on it. lol
In reality its a little more complicated than that.
A Race kite usually means that the sail is designed for max speed. This usually means you are going to get a kite that has a very high aspect ratio -
super long and very narrow. This type of kite cuts through the air very fast and has very little drag. The power comes from the speed. Just like an
airplane, the more speed it gets the more lift the wings will produce. The faster the kite flies the more apparent wind the kite will create, thus
the increase in power. The downside is usually at the cost of stability and gust handling. The kite will also tend to stall out more and be slightly
more difficult to launch and get moving, but once it does hang on for an explosive power curve.
Race kites tend to be much more costly to produce because you are working with a very fine line of being fast and powerful but also having some kind
of stability and control. If the kite is too fast then it will constantly over-shoot the window and collapse, if the kite is to touchy in gusty winds
then it will have a tendency to collapse and deflate, reducing control and making the kite difficult to fly. Because of these problems, race kites
usually need to go through hundreds of designs and changes to get to an end product that achieves what the designers are wanting. This means much
higher costs in research and development that need to be recouped through the production of the sails - thus ending up in a much more expensive kite
for the end users. The best Race kites will be the ones that have a very acceptable amount of stability, excellent control, minimal drag through less
bridles and efficient wing design, excellent upwind performance and all out mind boggling speed - like the Yakuza! (ok, had to plug the Yakuza there
and it is an obvious pimp, but you all know what I mean and I am sure the Gojo guys will be on here faster than you can hit your refresh button). LOL
Race kites do perform to the max but it is at a minimal amount of trade off for other features. If anyone gets the chance to try one of the Race
kites, jump on it right away, I am sure you'll be impressed.lunchbox - 22-9-2008 at 07:07 PM
Quote:
If anyone gets the chance to try one of the Race kites, jump on it right away, I am sure you'll be impressed.
Be warned however, you might like it soo much that you're not having quite as much fun flying your other kites...
another plug to the Yak...such an amazing kite!ripsessionkites - 22-9-2008 at 10:00 PM
... kites that make you go fast like the Nitro Evo II. (okay more than 5 words)
Yaks / GT
Nitro Evo II
Cooper
RM+
Combat
Spirit
Bora Race III
would be kites to look at in the "race" category
if you're looking for speed, thin profile, high projected AR, min. bridle lines, and a pair of B(*&.lunchbox - 23-9-2008 at 07:34 AM
Hey Rip...you forgot about the Sprint ;-)...sorry, I couldn't resist!acampbell - 23-9-2008 at 10:35 AM
Airplane (and kite) wing tips lose power and efficiency (called "tip loss"), due to the fact that the high air pressure under the kite surface that
normally produces the lift will "spill" over and around the wingtip. This action creates a vortex that swirls behind the wing and represents wasted
energy that creates drag (called induced drag).
When you increase the aspect ratio of the wing (longer and skinnier), a smaller percentage of the wing is wasted to tip loss, so the wing is more
efficeint. Along with the other things Kent mentioned, this is part of what makes a race kite faster- less induced drag.macboy - 23-9-2008 at 10:45 AM
So I'd also assume the "thickness" of the foil shape is to reduce the drag? I noticed the Sprint was uber thin....part of the reason it collapsed
unless it was moving forward I think? It's like a quarter the thickness of any other foil I've seen if not lees.Bladerunner - 23-9-2008 at 11:26 AM
Race kites are generally finicky in the way you describe. They are amazing but you have to really want the speed to put up with this style of kite
IMHO. They keep you on alert !
I prefer to not have to think so much about the kite :duh:
Quote:
Originally posted by macboy
So I'd also assume the "thickness" of the foil shape is to reduce the drag? I noticed the Sprint was uber thin....part of the reason it collapsed
unless it was moving forward I think? It's like a quarter the thickness of any other foil I've seen if not lees.
acampbell - 23-9-2008 at 11:50 AM
Quote:
Originally posted by macboy
So I'd also assume the "thickness" of the foil shape is to reduce the drag? I noticed the Sprint was uber thin....part of the reason it collapsed
unless it was moving forward I think? It's like a quarter the thickness of any other foil I've seen if not lees.
yeah that is certainly part of it. Reducing profile thickness and the number of bridles would reduce parasitic drag.lunchbox - 23-9-2008 at 12:54 PM
How does the number of cells and number of open cells as opposed to closed cells affect overall performance?awindofchange - 23-9-2008 at 02:51 PM
Generally speaking, the more cells in a kite (for a given size) the stiffer the kite will be in the air and the better the kite will hold its shape;
giving the kite better performance and less chance of luffing or distorting under flight - this all is dependent on the actual wing design of the kite
of course. Obviously the more cells a kite has the more material and construction costs there will be. Many of the high performance race foils are
using more internal bracing which has allowed them to reduce the number of bridle lines, reducing parasitic drag and increasing performance without
losing the solid shape of the wing.
The leading edge of the kite is usually the most important (for performance) with the trailing edge being second. The smoother the leading edge
curvature the better the air flow over the sail and the better the performance/speed. The cell openings in the leading edge of the kite can hinder
performance by disrupting the air flow, this is the main reason that race kites have a very small opening that is usually tucked underneath the sail,
closer to the bottom skin than right out in front. The designers of the race foils will do this to help give the leading edge of the kite a smoother
air flow. This does make it slightly harder to get the kite to inflate as the openings are not out in front where the main flow of air can get into
them. To help improve performance, most race foils will have the cells at the wing tips closed off completely (no intake vents). The smooth
perfectly formed leading edge on the wing tips helps with performance as well as keeping the wing tips inflated during turns. The downside to this is
that it takes longer to initially fill the kite because the air needs to enter into the center vents and then get forced down into the closed off wing
tips. This is one of the reasons that race foils will need some serious coaxing to initially get them moving. The location of the intake vents is
part of the reason that race foils don't like to stay parked in a static position in the lighter winds - mainly because the air doesn't give enough
velocity to keep the kite inflated due to the poor location of the intake vents. Once you get the kite moving the air pressure increases inside the
kite and you have full control/power.
Hope that helps.macboy - 23-9-2008 at 02:56 PM
This is amazing. I've learned so much not just about race kites but kites in general from this. Thanks everyone....keep it coming!andya - 23-9-2008 at 03:00 PM
Its the rigidity and smoothness of the aerofoil, that drives the number of cells
The more bracing across the depth and diagonally, the better the shape of the aerofoil is held. But the need for rigidity has to be balanced against
weight, and the need to get air into the foil to keep it inflated. So its a balancing act ...
Likewise the number, shape and position of the intakes. Again the designer is balancing the need to keep the foil inflated solid, vs. the desire for
a smooth drag free aerofoil without drag inducing intakes.
Look at the Nitro or the Combat, arguably the fastest in a straight line ... but come to a corner and they have difficulty keeping inflated due to the
small vents. Whereas the kite that wiped the floor at the 2008 Euro Chaps - the Spirit, has most cells open ... more drag on the straight, but kept
pulling and inflated through the turns ...
Now a closed cell racekite ... (think Vision, Neo, FS) that could be interesting ...lunchbox - 23-9-2008 at 10:32 PM
Ditto...Thanks for the great info on # of cells and open vs closed.
