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peppedurso wrote: ↑

Tue Mar 24, 2020 12:37 pm

what amount of weight saving can you predict in using DCF 102g/DCF 18g vs Dacron/Ripstop? is the kite going to be stiffer too?

Hi,
I made some quick calculations by changing the fabric weight in the software. Calculation is done for the GO in size 9sqm.
It's only the "naked" fabric weight. You have to add seam tape, patches, bridle, zippers etc. which will be another ~1000g

---------------------------------------------------------------------------------------------------------------
Fabrics (standard):
Dacron (tubes): 170g/sqm
Ripstop (sail): 60g/sqm
TPU (bladder): 100g/sqm
Kite:
Leading Edge 772g
Struts 279g
Sail 580g
Total fabric weight 1632g
---------------------------------------------------------------------------------------------------------------
Fabrics (dcf and light bladder):
DCF (tubes): 100g/sqm
Ripstop (sail): 60g/sqm
TPU (bladder): 60g/sqm
Kite:
Leading Edge 458g
Struts 166g
Sail 580g
Total fabric weight 1204g
---------------------------------------------------------------------------------------------------------------
Fabrics (DCF and light bladder):
DCF (tubes): 100g/sqm
DCF (sail): 20g/sqm
TPU (bladder): 60g/sqm
Kite:
Leading Edge 458g
Struts 166g
Sail 193g
Total fabric weight 817g
---------------------------------------------------------------------------------------------------------------
Fabrics: (DCF and very light bladder):
DCF (tubes): 50g/sqm
DCF (sail): 20g/sqm
TPU (bladder): 50g/sqm
Kite:
Leading Edge 286g
Struts 103g
Sail 193g
Total fabric weight 583g
---------------------------------------------------------------------------------------------------------------
Fabrics (DCF, ripstop, very light bladder):
DCF (tubes): 100g/sqm
Ripstop (sail): 50g/sqm
TPU (bladder): 50g/sqm
Kite:
Leading Edge 429g
Struts 155g
Sail 484g
Total fabric weight 1068g

The last combination is the one I will try

nixmatters wrote: ↑

Tue Mar 24, 2020 8:56 pm

[The kite (9m 3 strut hybrid) still flies in no wind, but the CF canopy project was ditched. Happy to see if somenone else will solve the shrinkage problem somehow. Before that, don't waste the nice material, make a tarp, tent or a backpack what it's made for.

Puuh, thanks for the warning! You are right it's probably not worth the risk. Saves ~200g but adds > $300.- to the bill
DCF makes more sense as a dacron replacement.

nixmatters wrote: ↑

Tue Mar 24, 2020 8:56 pm

Done some testing with CT1K18/25gsm - exactly same amount of Dyneema yarn and tensile strength as CT1E08/18gsm, but slightly heavier due to different/heavier laminate film. Tensile strength is in the upper range of a 53-60gsm Teijin ripstop, tear strength is double. Ended up using for the canopy CT2K18/34gsm - same laminate as CT1K18m, but double the amount of Dyneema yarn, so are the specs vs polyester ripstop.

Maiden flight - just awesome, but after just few hours of use and packing/unpacking the CF shrunk heavily (as it normally shrinks) and the shape was gone. Heavy TE flutter, even the dacron struts lost shape. The kite (9m 3 strut hybrid) still flies in no wind, but the CF canopy project was ditched. Happy to see if somenone else will solve the shrinkage problem somehow. Before that, don't waste the nice material, make a tarp, tent or a backpack what it's made for.
Will post some photos of the canopy when I find them, it's been 4 years since then. The kite came out at a bit over 2kg, with DP dacron LE/struts and 0,80 bladder, split pump.

Hi nixmatters,

it sounds like the DCF 20g is strong enough for canopy but it shrinks too much, shame! It sounded like a great option to save weight.
Is LE DCF not shrinking because of less stress/flutter?

PanTau wrote: ↑

Wed Mar 25, 2020 12:19 am

peppedurso wrote: ↑

Tue Mar 24, 2020 12:37 pm

what amount of weight saving can you predict in using DCF 102g/DCF 18g vs Dacron/Ripstop? is the kite going to be stiffer too?

Hi,
I made some quick calculations by changing the fabric weight in the software. Calculation is done for the GO in size 9sqm.
It's only the "naked" fabric weight. You have to add seam tape, patches, bridle, zippers etc. which will be another ~1000g

---------------------------------------------------------------------------------------------------------------
Fabrics (standard):
Dacron (tubes): 170g/sqm
Ripstop (sail): 60g/sqm
TPU (bladder): 100g/sqm
Kite:
Leading Edge 772g
Struts 279g
Sail 580g
Total fabric weight 1632g

---------------------------------------------------------------------------------------------------------------
Fabrics (DCF, ripstop, very light bladder):
DCF (tubes): 100g/sqm
Ripstop (sail): 50g/sqm
TPU (bladder): 50g/sqm
Kite:
Leading Edge 429g
Struts 155g
Sail 484g
Total fabric weight 1068g

The last combination is the one I will try

Hi PanTau,

thank you for your exhaustive answer. It looks like the best compromise is using DCF instead of Dacron for LE.
600g saved on 2,7kg is a 25% of total weight. Not groundbreaking but I'm sure it is quite a substantial an improvement.
Do you feel also the low end will benefits?
Using DCF 50g for LE and Struts would save 200g more, is the 50g one not stiff/strong enough? what is the benefit of the 100g over the 50g? I guess stiffness?

peppedurso wrote: ↑

Wed Mar 25, 2020 2:28 pm

Using DCF 50g for LE and Struts would save 200g more, is the 50g one not stiff/strong enough? what is the benefit of the 100g over the 50g? I guess stiffness?

VP22 built his GO with a DCF 50g leading edge and as far as I understood it worked. Don't know his body weight etc. but in general it should be possible and stable enough if you tape the seams and take care when pumping, launching and landing the kite. Ask VP22 for more details.
For me the DCF 100g seems to be a good compromise. Also for my wings.

peppedurso wrote: ↑

Wed Mar 25, 2020 2:28 pm

... Using DCF 50g for LE and Struts would save 200g more, is the 50g one not stiff/strong enough? what is the benefit of the 100g over the 50g? I guess stiffness?

Absolutely no difference in stiffness (mechacal properties) between 100g and 50g!
These are determined by the content of the Dyneema yarns, which is identical.
100g has an extra layer of dense woven fabric, 50g has just the laminated Dyneema non-woven Dyneema yarns in 0/90°.

The 100g can be sewn without reinforcement (insignia or dacron tape), but that's valid for tarps and backpacks, not LE!
I would still try lapped intersegment LE seams -
overlap the 2 segments, join with double adhesive tape and 2 tripple zigzag seams. This requires a very precise handling as with these seems the 2 segments have 'opposite' curves, making this method almost unusable for bulk production. Some brands tried it I the past resulting in twisted LE and kites pulling in one side.

PanTau wrote:

peppedurso wrote: ↑

Wed Mar 25, 2020 2:28 pm

Using DCF 50g for LE and Struts would save 200g more, is the 50g one not stiff/strong enough? what is the benefit of the 100g over the 50g? I guess stiffness?

VP22 built his GO with a DCF 50g leading edge and as far as I understood it worked. Don't know his body weight etc. but in general it should be possible and stable enough if you tape the seams and take care when pumping, launching and landing the kite. Ask VP22 for more details.
For me the DCF 100g seems to be a good compromise. Also for my wings.

Hi, with DCF 50g: the body weight = 950g for a 9m² with one strut. (ready to put in the bladder but without the bladder: 600g) total weight with bladder 1550g. You have to take care a little more than a standard kite production. my switchblade cabrinha 9m² weight body: 3,15Kg.

VP22 wrote: ↑

Fri Mar 27, 2020 8:52 am

So this is your closing seam reinforcement?

PanTau wrote: ↑

Fri Mar 27, 2020 10:54 am

VP22 wrote: ↑

Fri Mar 27, 2020 8:52 am

So this is your closing seam reinforcement?

yes for The LE. At the first time i use the usual seam with just one insigna. It was'nt enough. At the end of the first session i saw many rips (perpendicular at the LE seam, near 8mm) along the seam . But the LE didm't explode even with 0.8bar pressure. Unfortunately It was a "good test"
Now it's ok (from 6knots to 20-25knots). I'll see at the end of the season when we'll go back to the water.

VP22 wrote: ↑

Fri Mar 27, 2020 12:07 pm

yes for The LE. At the first time i use the usual seam with just one insigna. It was'nt enough. At the end of the first session i saw many rips (perpendicular at the LE seam, near 8mm) along the seam . But the LE didm't explode even with 0.8bar pressure. Unfortunately It was a "good test"
Now it's ok (from 6knots to 20-25knots). I'll see at the end of the season when we'll go back to the water.

And how did you reinforce the segment seams?