Crossbow Warning?
Posted: Sun Aug 14, 2005 9:40 pm
yeah, a warning about your Crossbows. Following is the email I sent Cabrinha after an episode at Crissy. Read the whole post and you'll get the full story. Email and response from Cabrinha. It's good, and you should know about it.
Original email:
Umm, yeah, where to start. Problem with the Crossbow 12m? Today was the thrid day flying my Crossbow 12m. I was in the bay, San Francisco, in the middle of everything. Literally a mile from anything. Just spent two hours flying the kite. In fact, I sent you an email yesterday raving about my first two days on the kite. Well, today, issue number one popped up, and vanished at the same time.
Issue: Flying the 12m in 20 mph winds, having a blast. Time to head in. Pulled a fast up turn, back through the power window. Right as the kite was passing the power zone, POW. POW as in the kite seemed to fold in half from the back forward, and turn inside out. Shit. I figured something broke. Ok, wrap up the lines, start the self rescue, managed to flag a boat, got to shore. Layed the kite out, and couldn't find anything wrong. Ok, will have to look into this tonight. Well, here it is, tonight, and I've run the lines/bar out, no problems. No breaks, no tears, no kinks, nothing. The bar and lines look perfect. Ok, I must have missed something on the kite. So, I pump the kite up and check all the bridle lines. Nothing broken, nothing out of place, no tears, nothing. NOTHING! Did I hallucinate?
Question: Is there some sort of flight maneuver I inadvertantly did to cause the kite to suddenly invert from the center strut, fold in half, and fall out o f the sky? This is exactly what happened. When I swam up to the kite, the center strut was pulled 180 degrees backwards, wrapping the kite in itself as it was folded in half. This was a pretty good indication to me that something broke. I found NOTHING! I'll be taking it out tomorrow to see if I can't find something when I fly it. I am baffled. I sure would appreciate some possible insight. The idea of using this kite just became a little sketchy if I can't find anything wrong with it and this happened. I mean NOTHING wrong that I can find. Believe me, I have scoured it. Anyway, I'll know more tomorrow, but am looking for any bit of info you may have.
Response from Cabrinha:
Thanks for contacting Cabrinha Support
The inversion that you experienced usually occurs from insufficient strut and/or LE pressure.
There is a reason why these kites do not have one pump and thatís because the struts need to be a higher pressure than the LE. If you have a strut that is not at pressure the LE can fold on that mark. If the LE is not a sufficient pressure it can roll and also fold in and invert. This usually occurs when the kite is put through the power zone but sheeted out. The low attack angle gets so negative that the canopy starts to blow down from the top side. When you have insufficient bladder pressures the kite simply has no support. BOOM, sheís inside out and in a knot.
Now there is a way to re-launch and get back to the beach if this occurs again.
You have to just play with the rear leaders and try to get the kite to lay out flat again.
Most people in this situation just start pulling on lines and this simply makes the kite knot up even more.
Swimming at it and trying to get it to spin around will get the kite back in the sky.
We have been testing the kite in these situations and it still stands as a 100% re-launch success in even the worst knots.
Result:
As you can see, basically end user error or a leak. I'm paying extra attention to the pressures. Cabrinha has been extremely responsive. This kite has been flying great ever since. Still highly recommended.
Original email:
Umm, yeah, where to start. Problem with the Crossbow 12m? Today was the thrid day flying my Crossbow 12m. I was in the bay, San Francisco, in the middle of everything. Literally a mile from anything. Just spent two hours flying the kite. In fact, I sent you an email yesterday raving about my first two days on the kite. Well, today, issue number one popped up, and vanished at the same time.
Issue: Flying the 12m in 20 mph winds, having a blast. Time to head in. Pulled a fast up turn, back through the power window. Right as the kite was passing the power zone, POW. POW as in the kite seemed to fold in half from the back forward, and turn inside out. Shit. I figured something broke. Ok, wrap up the lines, start the self rescue, managed to flag a boat, got to shore. Layed the kite out, and couldn't find anything wrong. Ok, will have to look into this tonight. Well, here it is, tonight, and I've run the lines/bar out, no problems. No breaks, no tears, no kinks, nothing. The bar and lines look perfect. Ok, I must have missed something on the kite. So, I pump the kite up and check all the bridle lines. Nothing broken, nothing out of place, no tears, nothing. NOTHING! Did I hallucinate?
Question: Is there some sort of flight maneuver I inadvertantly did to cause the kite to suddenly invert from the center strut, fold in half, and fall out o f the sky? This is exactly what happened. When I swam up to the kite, the center strut was pulled 180 degrees backwards, wrapping the kite in itself as it was folded in half. This was a pretty good indication to me that something broke. I found NOTHING! I'll be taking it out tomorrow to see if I can't find something when I fly it. I am baffled. I sure would appreciate some possible insight. The idea of using this kite just became a little sketchy if I can't find anything wrong with it and this happened. I mean NOTHING wrong that I can find. Believe me, I have scoured it. Anyway, I'll know more tomorrow, but am looking for any bit of info you may have.
Response from Cabrinha:
Thanks for contacting Cabrinha Support
The inversion that you experienced usually occurs from insufficient strut and/or LE pressure.
There is a reason why these kites do not have one pump and thatís because the struts need to be a higher pressure than the LE. If you have a strut that is not at pressure the LE can fold on that mark. If the LE is not a sufficient pressure it can roll and also fold in and invert. This usually occurs when the kite is put through the power zone but sheeted out. The low attack angle gets so negative that the canopy starts to blow down from the top side. When you have insufficient bladder pressures the kite simply has no support. BOOM, sheís inside out and in a knot.
Now there is a way to re-launch and get back to the beach if this occurs again.
You have to just play with the rear leaders and try to get the kite to lay out flat again.
Most people in this situation just start pulling on lines and this simply makes the kite knot up even more.
Swimming at it and trying to get it to spin around will get the kite back in the sky.
We have been testing the kite in these situations and it still stands as a 100% re-launch success in even the worst knots.
Result:
As you can see, basically end user error or a leak. I'm paying extra attention to the pressures. Cabrinha has been extremely responsive. This kite has been flying great ever since. Still highly recommended.