Front stall/collapse in high wind. Most likely culprit?

[tkaraszewski]

I've had a couple of front stalls in ~25 knots on a Flysurfer Sonic 3 9m recently. What's the most likely cause for this? The long mixer test has been done, and required nearly bottoming out the C-pulley adjustment to get everything straight (lengthening the B and C lines), but this doesn't seem to have made much difference with the stalls. What's the next thing you'd look at to get the kite behaving better? I want to increase the stability of the kite in strong and gusty wind (the collapses have occurred in Hood River, OR and Crissy Field, Santa Francisco, CA, both known for strong and gusty wind). The kite is relatively new with less than 50 hours flying time on it.

[Janus]

Hi, Don’t have experience with the Sonic3, but assuming it has the same (long)mixer setup as the soul.
When ABCZ are at same level, shorten C 1,5cm, B will follow 1/2 of it.
Try it again in same conditions.

[tkaraszewski]

Hi, Don’t have experience with the Sonic3, but assuming it has the same (long)mixer setup as the soul.
When ABCZ are at same level, shorten C 1,5cm, B will follow 1/2 of it.
Try it again in same conditions.

Yes, mixer setup is the same as the Soul. I can try that and see how it goes.

[Janus]

Ok, if it gets better but not enough.. shorten C another one cm.

[surfer]

I have been through frontal collapse in strong winds on Sonic 2 and recently Sonic 3 in 9m Both fixed.
The key to rectyfy frontal collapse is shortened B, make it shorter by about 2 cm using long mixer test. A/C/Z even.
My one year old kite needed 2 cm extensions for Z to be even with A and C on long mixer.
As alternative, You can youse topsail PMAs, shorten by one or two knots but at the cost ot turning speed.

[Oldman]

est my sonic3 sonic3 28393900 user_id=7603]
I have been through frontal collapse in strong winds on Sonic 2 and recently Sonic 3 in 9m Both fixed.
The key to rectyfy frontal collapse is shortened B, make it shorter by about 2 cm using long mixer test. A/C/Z even.
My one year old kite needed 2 cm extensions for Z to be even with A and C on long mixer.
As alternative, You can youse topsail PMAs, shorten by one or two knots but at the cost ot turning speed.
[/quote]

Where did you add the extensions to extend the Z line?
After the default long mixer test my sonic3 was rreally unbalanced. So just did a short mixer and it flew much better. Only had one frontstall so far.

[Breze]

Sorry for the blurred picture
Unsleve the junction of Back-Main, Z-Main & C-Sparepartline and sleve the knotladder btw Back-Main and Z-Main

The Soul has a figure 8 Knot on the outer junction of b7/8 and b9/10 to prevent tip collapse. Could also help on the Sonic if the collapse starts at the wingtips.

[Herman]

If not already done, do a bar tune before doing flight trials and tackling bridle shrinkage. Generally, lightly loaded areas shrink the most etc which introduces more camber resulting in the LE being more likely to tuck into a luff; slightly weird because it can be caused by Z. But unfortunately, I don’t have experience with the Sonic.

PS for group extensions add after the mixer to keep mixer check viable. For individual elements you can go as far down as the LCL if you are restoring to the line plan etc…….. Some stretching may be useful but in my experience it takes less time for shrinking to return compared to virgin line……

[Herman]

Not necessarily related to the OP’s Sonic, but if you want to see how a little Z pull can cause a frontal collapse have a look at the end of the Flysurfer YouTube vid for inflation and launching the Flare Moustache……. Just general info but a lovely clip of wing behaviour!

Search for: Flare - Nation academy 1

[juanpasala]

I ve had front collapses whilst going very hard upwind.
Got fixed by lenghtening a 0.5cm and shortening b 0.5cm