Bowtie remedies

[Ca Ike]

So I've seen some fixes for the bow tie issue revs are prone to and I'm curious as to why the dual angle outer edge is the chosen fix.  Lam does it on his ABS quad, Jon on his Djinn, Mat on his home builts.  Jon stated in another thread that the trailing edge of the sail is where the problem is in that as you give brake there is a point where part of the edge flips before the rest causing the upright to flip.  I noticed this on my rev today but where I saw it happening is along the trailing edge from the tip of the up right to about half way to the center panel and the more the center of the sail billows out, the easier it is to bowtie.  How does that dual angle on the outer edge stop the bow tie or is there another mod to the sail shape that does it?  I've toyed with the idea of a curved trailing edge inbetween the up rights as a fix but haven't tried it yet.

[Ca Ike]

In fact the only two quads I've flown that didn't bowtie are the original Mquad that just happens to have curved edges and the airbow.  My Solution quad will do it, my Hypnotic quad does it and of course my revs.

 

[Wayne Dowler]

The dual angled edge wasn't a fix for the flipping. It was for 45* landings and easier holding the upright position doing it. That angle allowed a little wind to pass through and cut back on resistance. JB mentioned it when he worked on the prototype.

The only "fix" I know are "magic sticks". The center truss line physically won't let the sail bowtie when used  with all the rest of the trusswork. I use them on my Zen.

Usually it's a sign of trying to reverse too sharply and over controlling when doing that. Bazzer made those little mesh panels on the Phoenix to shed off some of the back pressure when going from forwards to backwards, but too much still flips it. So the cure is you learning how much you can give in reverse, before it flips, that fixes it. Or go the magic stick route - it's the only physical "fix" I know.

[frob]

3 hours ago, Wayne Dowler said:

So the cure is you learning how much you can give in reverse, before it flips, that fixes it. Or go the magic stick route - it's the only physical "fix" I know.

This.

Unless you've got magic sticks which physically prevent the twist, it happens because you've pulled the trailing edge too far forward and physics pulls it the rest of the way.

I struggled with it too, I took videos to ask other people since there are few quad fliers near me, and practiced it for weeks trying to understand it.

When you are pulling on the bottom of your handle, you should feel a bit of tension. There comes a point if you pull a little harder that the tension quickly backs off to nothing. It is a very sharp transition, going from the kite pulling to the kite not pulling in perhaps two or three degrees of arc. That is the point where the sail is no longer capturing any air to pull it the direction you need. If you continue past that point by even a fraction of a degree, the air will push against the back, causing it to flip.

The leading edge transition is much more gradual, you have many degrees of arc before you start to flip, and usually that doesn't happen unless you're at the top of the wind window or doing some other glide parallel to the ground. When you flip, the entire leading edge moves together thanks to the spars, and you can do this during an axle. 

For me, the remedy to bowtie was to learn the flic-flac. It is an intentional flipping of both sides, then flipping back. If you feel one side start to flip you can either immediately flip the opposite side and perform a flic-flac, or immediately flip the one side that flipped getting it back to normal.

[makatakam]

Experience is the name of the game. Using a French bridle helps a bit but it still boils down to time on the lines. Try flipping one side, letting it make one spin and then flipping that side back.

[riffclown]

Personally I want my kites able to bowtie.. I intentionally bowtie them for a half-turn and landing.. I call it the inverted Kip landing.

That being said, like others, I don't like it to happen accidentally. I took the reverse approach and intentionally induced it until I got the break point pretty close. It not only helped with a few new moves but also made my inverted side slide much more stable.

The link between you and the kite is always fixed. With minor variations based on winds/conditions, no matter what you want the kite to do, it will blindly obey only what your hands tell it to do.

[John Barresi]

There is a little well-intended confusion on the Djinn outer trailing edge angles...

Primary purpose is to smooth out reverse (this works in confunction with the bridle).

What causes the wing to flip during reverse flight is wind getting past the trailing edge and on the back of the sail... Having filmed multiple slow motions tests, we found it starts with a small ripple in the outer trailing edge.

Breaking it down, the center trailing edge curves away from the pilot, therefore it’s further away from the “tipping point” than the sail outside the verticals, which doesn’t curve out very much, naturally keeping the outer trailing edge closer to the pilot, and the tipping point for bow tie.

The wind pass-through when resting on a 45 is an added bonus, but was not part of the original purpose.