GWTW Forum

Kites! Kites! Kites! => Kite Building and Repair => Topic started by: alien on May 12, 2013, 03:17 AM



Title: TUBULAR ROD FRAMES/HISTORY YET?
Post by: alien on May 12, 2013, 03:17 AM
Why havent kite frames evolved from a basic tubular rod,surely like nearly every other engineered thing on earth other than Ducati motor cycle frames have moved on to other geometric shapes for the torsional strength or flex,aerodynamics,lift, down force,production ease,price,weight savings and shape conforming benefits that they bring when applied correctly?
Is the modern kite missing out on these advantages?
Would not a thinner (SEXIER), oval or other shaped leading edge spar improve performance over a section of fishing rod shoved up a kite sleeve? Can you imagine a frame that you cant keep your eyes or hands off as its so good looking?
Is it,
The to hard basket?
Asleep at the strings?
Stuck in their ways?
Fittings to hard find or make?
NEXT........... ???
PS:Ive no understanding of kite design.


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: Hadge on May 12, 2013, 03:55 AM
Hmmm....I don't know too much about this but... My understanding of carbon fibre, especially 'shaped' components, is that while it can be made incrediblily strong in one plane it can also be very fragile in another. Look at Formula 1 race car suspension - very strong going up and down, but a small bump backwards and it breaks.

Going back to kites. You need the spars to be able to flex at an even rate in all planes - Ok tapered spars let one end flex more than the other but the degree of deflection remains the same. If you were to fit, say, oval spars ( apart from a massively increased cost) they will be stiffer in one plane than the other so your frame will bend more some times than others which is going to make flying them difficult to say the least. If you think about it they will be flexible in the narrow section plane but very stiff in the long section plane.

....at least thats my take on it, as I said I'm no expert.

( Bike frames etc are made with oval frames in order to restrict and control the amount of flex in a particular direction so you get more power through the pedals without losing energy with the frame flexing side to side).


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: alien on May 12, 2013, 04:20 AM
Hadge,
i forgot to put in one more question,
Is there something ive misunderstood about kites?
Good points hadge though i am only what-if-ing about frame shape.
Anything glass related thats "rolled" on a mandrel is not truly multi-rotational (in all planes)they actually have what is known as a backbone thats developed during manufacture from various causes and is normally used to an advantage to offer more strength or flex at or in various loads or directions,the oval and other shape variants actually make it easier to predict loads or flex prior to manufacture.
Would you believe?


Title: Re: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: cerfvoliste on May 12, 2013, 04:52 AM
While we are at it, why not just get rid of the frame and fabric, and go with a one piece molded wing with a bridle?
CV

Remember, No Matter Where You Go, There You Are.


Title: Re: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: Hadge on May 12, 2013, 05:11 AM
While we are at it, why not just get rid of the frame and fabric, and go with a one piece molded wing with a bridle?
CV

Remember, No Matter Where You Go, There You Are.

It would be quite difficult/bulky to transport though?

I have to admit to being a bit of a dinosaur here as I tend to prefer the simplest solution that works effectively - the kite is beautifully simple and effective, why complicate things?

( Anyway, if Aerostuff get the idea to make oval spars we'll have to sell both arms and legs to afford replacements! ??? :D)

Anyway, you won't be able to see how sexy your oval spars look when the kite is 80' up in the air! ;D


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: alien on May 12, 2013, 06:12 AM
Hadge,
 good points maybe? But performance gain is the question.  ???



Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: sugarbaker on May 12, 2013, 09:41 AM
Remember also that kite spars have some rotation while in use.  They not only flex, but twist.  I don't know how that effects an oblong spar, but it would be a component that required consideration.


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: zippy8 on May 12, 2013, 10:57 AM
Why haven't kite frames evolved from a basic tubular rod,surely like nearly every other engineered thing on earth other than Ducati motor cycle frames have moved on to other geometric shapes for the torsional strength or flex,aerodynamics,lift, down force,production ease,price,weight savings and shape conforming benefits that they bring when applied correctly?

Cost. And an appreciation for simple, elegant engineering solutions.

Quote
Is the modern kite missing out on these advantages?

Almost certainly.

Quote
Would not a thinner (SEXIER), oval or other shaped leading edge spar improve performance over a section of fishing rod shoved up a kite sleeve?

If you were able to correctly calculate and model just what the loads are on this structural member then a clever composites company (ie; Exel (http://www.exelcomposites.com/English/Segments/SportsAndLeisureIndustry/SportShafts.aspx)) could turn you out something curved, multiple thickness, variable reinforcement to order. Their high end Nordic walking poles (a "sport" they themselves invented to sell ski poles during the summer) are marvels of technology.

Quote
Can you imagine a frame that you cant keep your eyes or hands off as its so good looking?

No. No, I cannot imagine this. Nor do I want to.  :-[

What we have, which is mostly not-good-enough-for-archery tubes, work fine enough for our needs. In all honesty, anything more might well be an over elaboration that gains most in the "looks cool" department and doesn't actually make the kite fly appreciably better, assuming we can agree on what constitutes "better" in the first place.

Mike.


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: thief on May 12, 2013, 04:21 PM
While we are at it, why not just get rid of the frame and fabric, and go with a one piece molded wing with a bridle?
CV

Remember, No Matter Where You Go, There You Are.
See if you can find a picture of a Brookite Skua..........not a molded wing but quite along your lines


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: KaoS on May 12, 2013, 05:18 PM
Remember also that kite spars have some rotation while in use.  They not only flex, but twist.  I don't know how that effects an oblong spar, but it would be a component that required consideration.


Almost every traditional Asian kite uses rectangular cross section bamboo spars (or a close approximation, for the pedants).  This cross section actually has higher lateral rigidity and almost eliminates any unwanted rotation associated with circular cross section spars.  I have a small kite that started life with 2.5 mm fibreglass spreaders fixed to the sail at each end and in the centre.  When bowed, they tended to adopt this shape

(http://images60.fotki.com/v662/photos/7/1814857/10026245/cs-vi.gif)

Rectangular cross section carbon spars ,suitable for kite making, are readily available and eliminate this distortion.

While we are at it, why not just get rid of the frame and fabric, and go with a one piece molded wing with a bridle?



In Bali you can buy kites made from styrofoam that have a single towpoint.  Most of them are shaped like fighter jets.  They fly just fine

(http://images60.fotki.com/v367/photos/7/1814857/10026245/045-vi.jpg)(http://images54.fotki.com/v461/photos/7/1814857/10026245/044-vi.jpg)



Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: zippy8 on May 12, 2013, 05:35 PM
The behaviour of a kite's frame under load is.... complex.... to put it mildly.

(https://lh5.googleusercontent.com/-snJNteDQR74/UZA0gCOPemI/AAAAAAAAJa4/90F8ZzHhaXQ/w407-h845-no/Bendiness.PNG)

Trying to sort that little lot out dynamically and create something to effectively resist it or having a circular section tube that seems to get along fine... you decide.

Mike.


Title: Re: TUBULAR ROD FRAMES/HISTORY YET?
Post by: alien on May 14, 2013, 05:49 AM
The "keep it simple stupid" ideal  ???
Or it aint broken...yet!
That all does make reason for the frame not evolving any further than it should do.
But just picture a hotter,sexier,glossy... just kidding...zippy!  :P