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Taco-ing Rev 9M
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Post new topic   Reply to topic    Northwest Kiteboarding -> Gorge / Portland / Oregon Coast
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Pete

Since 29 Oct 2007
844 Posts

Opinionated



PostThu Jul 16, 09 9:24 am    Taco-ing Rev 9M Reply with quote

Noticed that when I park my 2008 Rev 9M when riding a wave, that the kite has a tendency to taco. If I fly the kite aggressively, obviously it's not an issue, but when there's not much wind in the kite, it seems to do this.

Anything I can do to address this? Thought I wasn't pumping it up hard enough, but I pumped it to 10psi, and still have the problem.

Is this a known problem with these kites, or am I just a dumb-ass?

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pdxmonkeyboy

Since 16 May 2006
6081 Posts
forever labled as the
retired kiter & motorhead Unicorn Master



PostThu Jul 16, 09 9:36 am     Reply with quote

Funny, I just posted this very same thing in the Octane thread. It is a very disturbing behavior that the REV exhibits. I brought it up in the past and lighter riders have not had a problem with it so I thought it was a fluke but every time I am very powered and I sheet all the way out, the canopy flutters and the kite puckers its leading edge under.

It seems to me it is a function of the kite having an extremely high angle of attack. When there is no tension on the back lines, the kite is almost parallel with the wind flow. From an aerodynamics perspective, the low pressure caused by the wind flowing over the bottom of the leading edge bladder is greater than the lower pressure of the wind now flowing over the top of the kite (which is essentially flat) and it gets pulled under. Just a theory though as I am by know means a kite designer.

I always rig my front line on the very last knot and the back lines on at least one or two knots towards the kite. This prevents the kite from getting really slack back lines but also reduces the amount of depower.

Not a deal breaker as I still really like the kite but it can be a tremendous bummer. Especially hot launching from body bashing wake style crashes. The kite will zoom off the water and fold, then take off and fold again.

I would love it if someone from SS or anyone with a higher understanding of kite aerodynamics could explain why this happens.

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Gman

Since 11 Feb 2006
4911 Posts
Portland
Unstrapped



PostThu Jul 16, 09 10:02 am     Reply with quote

wonder if you have too much tension in the back lines...

haven't seen this

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Kodiak

Since 01 Aug 2005
1114 Posts

Slidey



PostThu Jul 16, 09 10:08 am     Reply with quote

It would be not enough tension on the back line. I can make the leading edge flutter, but have only had a couple of times when it actually inverted.

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pkh

Since 27 Feb 2005
6549 Posts
Couve / Hood
Honored Founder



PostThu Jul 16, 09 10:15 am     Reply with quote

make sure its pumped up to at least 8psi

I have noticed that pretty much all bad behaviors can be fixed with more LE pressure.

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pdxmonkeyboy

Since 16 May 2006
6081 Posts
forever labled as the
retired kiter & motorhead Unicorn Master



PostThu Jul 16, 09 10:16 am     Reply with quote

pkh wrote:
I have noticed that pretty much all bad behaviors can be fixed with more LE pressure.


that's what she said Laughing

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Wind Slither

Since 04 Mar 2005
2627 Posts
The 503
METAL



PostThu Jul 16, 09 10:18 am     Reply with quote

I can't say I've had a taco, but I think I know what you're talking about when you say that if you're overpowered on a Rev and you sheet all the way out.

The canopy gets bent out of shape and they don't turn because there's no tension in the back lines. Sometimes, while in this state, the kite will decide to rocket across the window and it's tough to regain control because you don't have any tension in the back lines.

I just assumed this was a trait that's more pronounced with SLE's and the answer is to error on the side of under-rigging vs. overrigging.

I've also seen similar behavior with C's.

The Rev is still the SWEETEST handling kite I have ever flown... Thumb's Up

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blowhard

Since 26 Dec 2005
2027 Posts

Windward



PostThu Jul 16, 09 12:18 pm     Reply with quote

I've never seen a sle that didn't invert from a leading edge wingtip stall
causing the kite to unwind.
That's not what I call a taco
to me taco is the kite folding into half,
usually from lack of pressure in the leading edge
(and this does of course happen after the invert)
I've expierenced "taco's" from over powereing the kite
such as when using short lines with c types
I always fly sle kites at 80% of full power with only about a foot of trim
just to avoid inversions (and the kite zenithing )(and flapping)etc
but with c kites on longish lines they will become unmanageable
much sooner ,causing me to stop and put up the correct kite Cool

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scottm

Since 12 Jun 2006
108 Posts

Stoked



PostThu Jul 16, 09 2:07 pm     Reply with quote

Try adjusting the stopper ball down to where the kite is mostly depowered when you sheet out. Helps keep the kite from stalling out.

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Pete

Since 29 Oct 2007
844 Posts

Opinionated



PostThu Jul 16, 09 5:16 pm     Reply with quote

Maybe a little clarification. Monkeyboy mentioned inverting, but I haven't had this problem. The kite falls back in the window, and the wingtips come together. Usually, it catches enough wind to open back up, but the jerk that comes along with that is not too much fun, especially when trying to ride a wave.

As I said, the kite is at 10 psi per the Slingshot gauge I have. Feels plenty hard as well.

Also, this does not happen when sheeting out. It typically happens when I am not sheeting in or out.

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jackZ

Since 13 Apr 2008
355 Posts
Devon Alberta ca.
Obsessed



PostThu Jul 16, 09 9:06 pm     Reply with quote

get a kahoona Surprised

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Moto

Since 03 Sep 2006
2698 Posts
Still a gojo pimp!
Moto Mouth



PostThu Jul 16, 09 9:29 pm     Reply with quote

Throw some tapatillo on that bad boy!!!
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Kataku2k3

Since 14 Aug 2005
3754 Posts
PDX-LA
Videographer



PostThu Jul 16, 09 9:40 pm     Reply with quote

Sounds almost like it's over-sheeted... Have you checked your lines to make sure they're all equal? If not, what about depowering the bar a bit? Does that help?

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Nak

Since 19 May 2005
4316 Posts
Camas
Site Lackey

CGKA Member


PostThu Jul 16, 09 9:54 pm     Reply with quote

Kataku2k3 wrote:
Sounds almost like it's over-sheeted... Have you checked your lines to make sure they're all equal? If not, what about depowering the bar a bit? Does that help?


Thumb's Up

That would be the first thing I'd check too. It seems like not all of the 800# lines were pre-stretched enough, some of these get way out of tune. If you had two lines that weren't pre-stretched, you could get way out of tune and over-sheeted... I've never had this happen to one of my REVs. I've gone out way over and under powered. I pump to 9 psi and religiously tune my bars.

Check your bridles too. Compare the lines symmetrically from the left to the right side. Opposing lines should be equal length. My 11m REV started doing weird things, turns out the bridle was stretched asymmetrically.

One note: Two of my REVs bridles got lopsided 'cause I always boost on starboard tacks. SS replaced my bridles with no questions asked under warranty. NICE customer service!!! Thumb's Up I really need to work on port tack jumps!

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Pete

Since 29 Oct 2007
844 Posts

Opinionated



PostFri Jul 17, 09 7:43 am     Reply with quote

Nak wrote:
Kataku2k3 wrote:
Sounds almost like it's over-sheeted... Have you checked your lines to make sure they're all equal? If not, what about depowering the bar a bit? Does that help?


Thumb's Up

That would be the first thing I'd check too. It seems like not all of the 800# lines were pre-stretched enough, some of these get way out of tune. If you had two lines that weren't pre-stretched, you could get way out of tune and over-sheeted... I've never had this happen to one of my REVs. I've gone out way over and under powered. I pump to 9 psi and religiously tune my bars.

Check your bridles too. Compare the lines symmetrically from the left to the right side. Opposing lines should be equal length. My 11m REV started doing weird things, turns out the bridle was stretched asymmetrically.

One note: Two of my REVs bridles got lopsided 'cause I always boost on starboard tacks. SS replaced my bridles with no questions asked under warranty. NICE customer service!!! Thumb's Up I really need to work on port tack jumps!


I've never checked the tuning of my lines, or my bridle.

I think this has been discussed before how to do it. Anyone have the link bookmarked?

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shymac

Since 20 Jul 2005
919 Posts
Home Valley, Wa.
Bigfoot



PostFri Jul 17, 09 8:04 am     Reply with quote

If you having trouble you can always call Slingshot toll free.

Slingshot Rider Hotline- 1-877-775-7238

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Alien

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rich

Since 30 Nov 2005
306 Posts
portland
Obsessed



PostFri Jul 17, 09 8:05 am     Reply with quote

i always shit when people start talking about unequal line lengths, scary and super inconvenient.

If you figure out the issue w/ this let us know. i'm not having it w/ mine, but would like to know the fix just in case.

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