Found on the www.neilprydemaui.com/forum/phpBB2/viewforum.php?f=2 site are some more pics of the crossbow as well as the 2006 Contra. The moderator also claims release date for the 2006 Crossbow is this Friday, July-1 on the cabrinha homepage.

quote:

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Originally posted by dachopper

the only reason a foil has better efficiency is because it has highest lift / to weight ratio....... the canopies are stretchy and soft, and as such your ride is soft, and turns are slow, depower generally less..... more efficient technically, but all kites are efficient enough to achieve their aim of upwind and big jumps, it's the other reasons people choose foils, cheaper, smaller to packup, faster to setup, easy to travel with due small size.

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Just curious Dachopper
How did you come by this info, which states that parafoil kites are inherently more efficient than inflatable sled designs?
How many and which models of parafoil kites have you flown lately?

Cya and

Goodwinds

Steve McCormack

Dachopper you have to be kidding, right!!??

All this based on the nasa websites explantion of why single line kites fly, explanations of lift for wings powered by engines, and paraglider foils (none of these are steerable AOA changing inflatable sled foils or steerable KITES) and your experience with one 2002 9M Flysurfer.

Some of the fastest and most efficient kites I have ever flown are single skin.
An eficient traction kite is one that will allow a user to travel at high wind speed multiples, thats just my opinion. The highest multiple of wind speed I have ever achieved was with single skin kites.

Of course in kitesurfing we do not just want to go fast, so super aerodynamic efficiency is not the design goal.

If twinskin foils in low air speeds are so efficeient why are they not used in racing yachts and windsurfer sails?

Completely flat kites with projected area and actual area sizes being identical don't exist.

What parafoil kites have you weighed, and compared to inflatable sled kites? Names and brands and sizes please?

Your claim for efficiency seems to be solely based on the size difference between your old Flysurfer and the inflatos your companions were out with, rather than how one design flies and performs measured over against other designs.

We don't want super efficiency for a kitesurfing kite, we want a kite that will re-launch, and have good tractable upwind power and jumping ability, combined with tight turning and depowerability.

There is so much nonsense posted about parafoil (paraglider) aerofoils efficiency and airplane high speed airfoils, try to remember these are kites we fly eh!?

Parafoil kites like flysurfers have a major efficiency hurdle, the massive bridles and pulleys hanging off them, as well as the large number of profiles that separate the 2 skins, it is a credit to the designers of kites like the FS, Ozone Frenzy, Flexifoil Sabre, etc that these kites perform as well as they do.

There is one very efficient kitesurfing foil though, that has no bridles, the Peer Lynn Arc style kite, especially the new Venoms, and guess what, they are a sled type kite design!

Cya and

Goodwinds

Steve McCormack

quote:

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Originally posted by dachopper

if you want to know the reason... then just log onto the NASA websight, lookup aerofoil designs, and you will see that under the wing profile library that they have which contaions the most aerodynamic foils, gliding foils etc... my defeinition of efficiency is basically a trade off between lift and drag(or kite speed) ,and weight influences the performance also... inflatables don't have a continuous foil for wind flow, whereas .. for instance a flysurfer does, not to mention the projected are of a flysurfer is alot closer to the actual area... ie becasue of their shape the current range of LEI's for a 15square meters of sail, might be 9 meters actuall.. compare that to a flat& complete aerodynamic foil which will have 15 meters actuall, and 15 meters useable as the sides are not drapped down pulling against each other for no benifit other than to keep the kite's shape. and add that to the lower weight, and then add in the aerofoil is complete, and not half and you have more reasons for it to be more efficient, also y lug around a whopping 16 or 20 meter LEI when a 9 or 14 meter foil will give the same pull.., there are of course positives and negatives for haveing a more efficient wing.. ie, without incorporating solid flaps or Leeding Edge Flaps then steering can be slower, which some manufacturers may tackle in newer models like what slingshot did with the machine battern tips, also relaunch after crashing in waves with a bridle getting tangled would be a negative.. and i would guess, not haveing ridden one myself... it would be hard to dump lift, ie depower an extremely efficient foil when the wind picks up without changing the shape of it, given that air is the only thing holding the shape together .. I havn't flown parafoils lately, my only experience is a 9 meter flysurfer 02 model which pulled like a 14 LEI, and is allways out in less wind that the LEI guys use their 9 meters in.. hence more efficient.

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All that crappy 'bridle' spaghetti might trigger a kitemare for me in the surf.
A string-surfer strung-out.

"Your claim for efficiency seems to be solely based on the size difference between your old Flysurfer and the inflatos your companions were out with, rather than how one design flies and performs measured over against other designs."

We don't want super efficiency for a kitesurfing kite, we want a kite that will re-launch, and have good tractable upwind power and jumping ability, combined with tight turning and depowerability.

that's exactly right dude, all i was claiming is that for that paticular style of foil. open and flat, the projected area is closest to the useable area fact1. hence you will get more pull or lift per square meter of kite size fact 2, hence the kites weigh less becasue a 9 square meter acutal pulls as much as a 14 square meter actuall LEI so you would weigh the two sizes and one will weigh more than the other I don't own a store or sell kites so if you do you could wiegh them and prove me wrong... I don't own flysurfers or any foils, and don't actually fly foils at all because of my perception of their lack of depower, and the bridle tangle problem, which may well have been improved or fixed since I had ridden the 02 model .. I'm not rating foils above LEI's..... isn't efficiency about getting the job done ie what other kite can you fit in a schoolbag with bar, lines and wiast harness, have no need for a hand pump, and be able to take a smaller size kite for the same wind as carry on luggage when on an airplane?

Im sure if you doubt me... there would be plenty of flysurfer riders out there that can vouch that the square meters of their models, pull harder than the sled types.., this only really pertains to the flat foils

Just give me some wind

which is the fastest kite?

www.stormboarding.com/pages/2/index.htm

Not alot of difference but it is interesting!

that's exactly right dude, all i was claiming is that for that paticular style of foil. open and flat, the projected area is closest to the useable area fact1.


I'm just commenting on your CLAIMS that you in no way are substantiating.
Just because you write Fact1, does not make your assummptive statement a fact. The ratio between flat area and projected area in a given kite design is not an indicator of efficiency, by any definition.



hence you will get more pull or lift per square meter of kite size

Big Assumption, based simply on the amount of cloth used, or the difference between flat and projected areas of a kite.
Means sweet FA about efficiency, by any definition!


fact 2, hence the kites weigh less becasue a 9 square meter acutal pulls as much as a 14 square meter actuall LEI so you would weigh the two sizes and one will weigh more than the other I don't own a store or sell kites so if you do you could wiegh them and prove me wrong...

You are forgetting that there are TWO skins, PLUS risers/profiles/, dividing each cell creating the airfoil shape as well as reinforcements, bridle tabs, etc AND bridles/pulleys, etc.
I do own a shop, and I do fly foils like you describe, and things like Peter Lynn Venoms, the weight difference in kites of equivalent power is minimal and insignificant overall, in this discussion.


I don't own flysurfers or any foils, and don't actually fly foils at all because of my perception of their lack of depower, and the bridle tangle problem, which may well have been improved or fixed since I had ridden the 02 model


I do own these types of kites, and I do actually fly all these types of kites. Depower in foils like FS, Frenzy, Sabre is as good as any LEI, and kites like Venoms have as much if not more depower than LEI's, perception is not something that is often a good indicator of performance and efficiency in kites.
Perception is very subjective, and based on your experience has lead you to post very biased information and claim it as FACTUAL.
That is all I am addressing in my replies.




.. I'm not rating foils above LEI's..... isn't efficiency about getting the job done

Then if that is your definition of efficiency, LEI kites, FS/Frenzy/Sabre style foils, and Peter Lynn Venom style kites all fit the bill, and preference becomes one of personal choice. Rating one kite over another is such a subjective exercise, that it becomes worthless to most of us here. If you like your kite and it does the job for you, that is the main thing eh?



ie what other kite can you fit in a schoolbag with bar, lines and wiast harness, have no need for a hand pump, and be able to take a smaller size kite for the same wind as carry on luggage when on an airplane?

You're assuming again. Foils don't pack up that much smaller, not when you take into account the bar and lines. Sure LEI's require a pump, but on my recent trip I fitted my 13M Hellfish in my hand luggage complete with pump.
My friends with foils had luggage weights and volumes virtually the same as me, except I had 3 kites and 2 boards, they had 1 board and 2 kites each, go figure!


Im sure if you doubt me... there would be plenty of flysurfer riders out there that can vouch that the square meters of their models, pull harder than the sled types.., this only really pertains to the flat foils

Experienced FS/Frenzy/Sabre users would not make an issue about this, they know the difference between flat and projected sizes between 2 vastly different kite designs is not a determinant or indicator of efficiency, by any definition.

Widen your perspective, fly more kites. And perhaps do your cred a favour and don't make sweeping assumption and generalisations until you do?
In the meantime enjoy YOUR kites, and allow everyone else to do the same eh?

Cya and

Goodwinds

Steve McCormack

"The ratio between flat area and projected area in a given kite design is not an indicator of efficiency, by any definition."

so your saying it doesn't matter that close to 50% of the lift created by a sled design is not pointing the same way the kite is going, of course you won't believe that claim so look at the cabrinha borchure for the crossbow caus thats what they claim in there ..ie 50% of lift lost.

.. the fact that you HAVE to use a larger kite if yor comparing a flat foil , (not a peter lyn venom) to a sled design?? you have to use a larger LEI to get going , compared to a flat foil because they are more efficient!! what's to argue about.. the land speed "record" is a flysurfer I believe, a speed 7 or 10... another flat foil.....

when you ask for an efficient car you talking of litres of fuel per hunderd km's, kites are the same, efficiency isn't " best features"

the definition of Efficiency is...

The ratio of the effective or useful output to the total input in any system.
b. The ratio of the energy delivered by a machine to the energy supplied for its operation.

so if your sled design is " wasting " 50% of it's lift on keeping the kite flying, then by the maquarie dictionary definition of efficiency ,( because i don't know what it is and apparently neither do you)... then flat foils , who don't waste 50% of their lift on keepin shape as opposed to their job of pulling a kiter are more efficient

quote:

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Originally posted by dachopper

"The ratio between flat area and projected area in a given kite design is not an indicator of efficiency, by any definition."

so your saying it doesn't matter that close to 50% of the lift created by a sled design is not pointing the same way the kite is going, of course you won't believe that claim so look at the cabrinha borchure for the crossbow caus thats what they claim in there ..ie 50% of lift lost.

No it does not matter, because the kite works, and works very well. I look at work done, and sailing efficiency, as the only "efficiency" I am interested in as a kite flyer. Fly more kites and you will see that FS/Frenzy/Sabre type bridled depowerable foils are not that much more effiecient, if at all.
Have a look at a FS/Frenzy/Sabre kite side on, they are a long way from flat, and in fact have an extremely curved canopy.
These are kites, not wings for supersonic jets!!!!!!!!!!

.. the fact that you HAVE to use a larger kite if yor comparing a flat foil , (not a peter lyn venom) to a sled design?? you have to use a larger LEI to get going , compared to a flat foil because they are more efficient!! what's to argue about.. the land speed "record" is a flysurfer I believe, a speed 7 or 10... another flat foil.....

The land speed record is higher than what is on that website, I know of people who went around 125kph in a buggy, some years ago. I was at Lake Gairdner and saw a friends speedo with a similar speed recored as max for the session, after we were hit by a storm.
Speed records are cool, if thats what you want to do, personally I have no interest in flying that sort of kite for everyday use.
The FS speed on that website is only a few % faster than an LEI, and I am absolutely sure some madman on a good small LEI can go as fast as the FS Speed.

You keep forgetting that a bridled or any type of twin skin parafoil kite has 2 skins, and actually has a lot more sail or cloth area than a comparable single skin kite????

Once again look at a FS/Frenzy/Sabre kite in side profile, they are very curved. The crossbow claim is in relation to the projected area of some LEI type sled kites.
The ratio of projected area, to flat sail area, IS NOT, THE definition of efficiency in a kite design, get over it.

when you ask for an efficient car you talking of litres of fuel per hunderd km's, kites are the same, efficiency isn't " best features"

the definition of Efficiency is...

The ratio of the effective or useful output to the total input in any system.

Notice the word useful?


b. The ratio of the energy delivered by a machine to the energy supplied for its operation.

so if your sled design is " wasting " 50% of it's lift on keeping the kite flying, then by the maquarie dictionary definition of efficiency ,( because i don't know what it is and apparently neither do you)... then flat foils , who don't waste 50% of their lift on keepin shape as opposed to their job of pulling a kiter are more efficient

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You seem obsessed with being right and spending a great deal of energy and bullying words on here to prove others wrong, good for you.
I'd rather be happy.

Cya and

Goodwinds

Steve McCormack

Hey chop chop - good discussion and obviously you have done your aerody study. You can never out-logic someone who believes deep down they know everything about everything and thats what your up against here. Its like arguing with the mormon who comes door knocking. He's never going to say " oh yeah ya right, maybe there isn't a god. thanks for convincing me. I might go get laid instead" no matter how good your arguments are.

Dear God,

Please bring winds early this year, and
thanks for listening..

Thanks heaps, love your work,
robbo.

I logged in to the Neil Pride site to see the latest on the Crossbow it seem KBM (magazine) have used this to trash Safari Lodge again.

Geeez they are angry.

Let hate rule!

BRING BACK BREAST
THE MOTHER OF ALL KITES

MORE MILK PLEASE MISSUS

That looks good (and I'm a poor misguided Poley), The vids make interesting viewing.

The K crew look to be getting some good inovation this year

You lot are going to be realy annoying in the surf

Alby