GWTW Forum

Kites! Kites! Kites! => Kite Building and Repair => Topic started by: Allen Carter on April 19, 2011, 02:59 PM



Title: Zero Air Reframe
Post by: Allen Carter on April 19, 2011, 02:59 PM
I got a bunch of the new Skyshark Zero Air sticks at the Kite Party Auction and I've been looking forward to this project.

These new sticks are awesome! At under 7 grams each, I believe they are the lightest wrapped tubes on the market.

I've had PBSK Vanishing Points in a variety of frame configurations over the years. My favorite frame for the VP came in my ugly old '96 model. In those days the tapered sticks from Skyshark were called Response tubes and the 7.5gram version is the Response Zero. I've been using that old Response Zero frame in a newer VP sail for a couple years and it's sweet.

As the Response sticks have been out of production for well over a decade, they are getting hard to find and so I started to think about a new frame. A year ago the best option was GForce Skinny ULs at 7.5 grams. Excellent sticks. I was just getting ready to buy a bundle of these when AVIA closed and the future of these legendary sticks was unknown. I held off buying Skinnys and then heard about the new Zero Airs. 

OK, on with the project. The old Reponse Zeros have a pretty strong taper. They are very small diameter at one end. They are very flexible at the small end and fairly stiff for their weight at the big end. They feel different in a kite compared to Skinnys, 2PTs, etc.

The new Zero Air sticks have a very gradual taper. They are much larger at the small end than the old sticks. This difference in flex curve will certainly change they way a kite feels. As I've flown VPs with a variety of frames and understand the dynamics, I think the Zeros will be very good in some ways.

The new Zeros take a .2300 ferrule. At Jon T's suggestion I used a piece of the older style 2P wrapped rod to make light weight LE ferrules. I used pultruded .2300 for the center T ferrule for a bit of added strength.

The kite is ready to go, but not flown yet. Overall the frame feels stiffer just doing the center t shake. I always thought that the flexible tips on the old lower spreaders were a weak point.

While the new sticks are a bit lighter than the old, I upgraded from the old (but light) tube fittings to TAPAs, so the finished weight is probably about the same (cant find my scale)

Now for some early morning flight and abuse testing. It will be interesting to see how durable these super thin wall sticks are (relative to the old frame).



Title: Re: Zero Air Reframe
Post by: Lee S on April 19, 2011, 10:22 PM
Can't wait until we get the flight tests!  I'm wondering if you think the rods are strong enough for a std to light re-frame. (like, for example, make a Bad Boy into a Bad Boy UL kind of thing) As the small ends are bigger than the Skinnies, what did you use as the knocks on the tips?


Title: Re: Zero Air Reframe
Post by: Allen Carter on September 30, 2011, 10:20 PM
Wow, that's gotta be a record for a completely reframed kite to sit idle in my bag unflown. 5 months before I got some good 0-2 type wind to try this thing. Had it out twice this week and it's great.

The Zero Airs worked pretty much like I expected. The frame is stiffer overall which makes the kite more responsive. Going for TAPA fittings instead of the super light but more flexible vinyl tubes also helped achieve the overall robust feel.

Flight performance was great right out of the bag. The only tweak I need to consider is a lighter upper spreader. Don't know what I'd make it out of, cause I think thinner pultruded would be too bendy. Maybe not. This kite doesn't get flown over 4 mph.

The lighter spreader will flatten out the flat spins a bit more. Under controlled spins the kite looks good, but floating down wind in a pinwheel its a but off kilter.

So, with about two hours on them I can say the Zero Airs live up to my expectations.

Lee, I have so many fittings, I don't know specifically what I used. I just try stuff until I find something that fits, then hope I have two or three of them.


Title: Re: Zero Air Reframe
Post by: mikenchico on October 01, 2011, 09:18 AM
Short lengths like an upper spreader always seem surprisingly stiff to me, IMO you would be fine with almost anything up there on an xSUL kite like you seem to be building, you are not going to really hammer on it anyway having used a hollow pultruded Center T.

What are you using now? Those Zero Airs come in at 6.9 grams with a 1.06" deflection, in the pultruded bag you'de have choices between the .1570 which weighs in at 9.3 grams with a 1.6" deflection, or the .1250's that go 6.8 grams with a 3.9" deflection, and the new .1250 thin wall at 6.3 grams, I'd have to run Simons equations to get a deflection, more then 3.9 in any case. I bet you could drill an TAPA-U out enough to fit over the Zeros on an xSUL.

If you're worried about stiffness the lightest available straight wrapped tube is the Avia Breeze at 7.5 grams (recent figure 6.75g) and >1" deflection but they will probably be getting pretty scarce. The next option is a Skyshark 2P which I had at 8 grams but Steve shows at 9 grams, my figures show a .8" deflection and you'd have to drill out a TAPA W or X to fit, and the wrap edges will be pretty hard on your rub patch, you'll need some Moonie Tape or a foam pencil grip. A P90 runs 10.5 grams with a .565 deflection.

Myself, on an xSUL i'd go with a .1250 light since I'll fly without an upper spreader if needed, you know like your new TTUL that never had an upper spreader. But Bettencourt's have a pretty wide nose don't they? they might get a bit strange without some support there.


Title: Re: Zero Air Reframe
Post by: Allen Carter on October 01, 2011, 10:23 AM
It's a pretty long US and the kite isn't right without it. As your numbers show, the .1250 is really bendy at this length. I'm going to try it, though because I have the stick. The other strategy would be to reverse the tapered spine and shif some weight that way, but would probably be overkill. While I'm morally opposed to adding weight to SULs it might be the right thing at this point. A few grams in the tail would do the trick and I wouldn't have to mess with what seems to be a winner of a frame


Title: Re: Zero Air Reframe
Post by: ae on October 02, 2011, 01:14 PM
XULs, my bag of stuff :)

I'm planing to use the Zero Airs for my Spectre, since it could use some more stiffness.
However the lightest rods on the market are the Avia Breeze 2 at ~6grams. Thats why i have in my 2nd Spectre, they work well without a problem up to about 8km/h wind speed. The Zeros would most likely extend that wind rang up a bit and cost a tiny amount at the lower end since they weight more. But as Spreader it should be good.
Deflection of 1" is about the stability limit you want in a full size kite for the spreader, leading edges can be softer, but you can get a problem keeping the trailing edge tout, and silent.

My third Spectre has custom rods which are ~5grams, that is stable enough for about 5km/h wind speed.

If you aim for weight reduction, don't underestimate the weight of all the little pieces, it adds up quickly.

For my next Spectre I will probably use breeze 2 leading edges, skinny ul keel, since i can get them in 40" length, and zero airs for the lower spreader. And i have a few breeze left for the top spreader.

What works very nice for the Breeze 2 as ferrule are easton ACE 1206G / 670 arrow shafts, the fit snug into the breeze2 and are very sturdy and light.