After having owned the Balz Pro 799 and 899 I recently switched to the MEDUSA PRO 869.
Overall I'm quite happy with it as this front wing is doing amazingly well for its size. However I had a few occasions where I suddenly crashed, without any clear reason. When this happened I was going in a straight line, half-wind course, standing straight above my board (so no angle to the water surface) at some 30+ km/h. A descent speed but nothing spectacular. It felt like the front wing instead of creating lift, suddenly switched to creating a dive-motion, causing me from a glide to a sudden nose-dive+crash.
By the way I never experienced anything like this on my previous 799 and 899 front wings.
Anyone an idea of what is happening here? Any similar findings? Or maybe a tip how to solve this?
The SABFoil gear I use:
Mast - M83K
CARBON RAIL PLATE - CP02K with Q01K quick release system
Fuselage - F703K
FRONT WING - MEDUSA PRO 869
Stabilizer - S399
Select to expand quoterkolijn said..
After having owned the Balz Pro 799 and 899 I recently switched to the MEDUSA PRO 869.
Overall I'm quite happy with it as this front wing is doing amazingly well for its size. However I had a few occasions where I suddenly crashed, without any clear reason. When this happened I was going in a straight line, half-wind course, standing straight above my board (so no angle to the water surface) at some 30+ km/h. A descent speed but nothing spectacular. It felt like the front wing instead of creating lift, suddenly switched to creating a dive-motion, causing me from a glide to a sudden nose-dive+crash.
By the way I never experienced anything like this on my previous 799 and 899 front wings.
Anyone an idea of what is happening here? Any similar findings? Or maybe a tip how to solve this?
The SABFoil gear I use:
Mast - M83K
CARBON RAIL PLATE - CP02K with Q01K quick release system
Fuselage - F703K
FRONT WING - MEDUSA PRO 869
Stabilizer - S399
When I first started using the W1000 I had a similar experience and found that putting a 0.5 shimm on the rear stabiliser sorted it out and it has never happened since .
Select to expand quoteBritfoil360 said..rkolijn said..
After having owned the Balz Pro 799 and 899 I recently switched to the MEDUSA PRO 869.
Overall I'm quite happy with it as this front wing is doing amazingly well for its size. However I had a few occasions where I suddenly crashed, without any clear reason. When this happened I was going in a straight line, half-wind course, standing straight above my board (so no angle to the water surface) at some 30+ km/h. A descent speed but nothing spectacular. It felt like the front wing instead of creating lift, suddenly switched to creating a dive-motion, causing me from a glide to a sudden nose-dive+crash.
By the way I never experienced anything like this on my previous 799 and 899 front wings.
Anyone an idea of what is happening here? Any similar findings? Or maybe a tip how to solve this?
The SABFoil gear I use:
Mast - M83K
CARBON RAIL PLATE - CP02K with Q01K quick release system
Fuselage - F703K
FRONT WING - MEDUSA PRO 869
Stabilizer - S399
When I first started using the W1000 I had a similar experience and found that putting a 0.5 shimm on the rear stabiliser sorted it out and it has never happened since .
That's the standard -0.5 degrees shim of SABFoil you refer to, right? As I also read that some people were using positive shimming (by reversing a standard Sabfoil -0.5 shim)
I'll try so for my next session. Thanks.
I thought to share this here, as it might help others with the same issue.
I have added a rubber O-ring around the mast at about 15 cm above the fuselage (see picture) which is supposed to block the ventilation towards the stabiliser.
This seems to be working for me!
Not unusual with glossy masts, make sure you clean the foil with window cleaner just before you hit the water and then don't touch it. Any greasy finger prints on the foil will help aid ventilation at higher speeds. Race sanding the mast to a nice matt finish really helps too.
Your new wing is probably a bit quicker and your now in the world where kitefoilers struggle with ventilation, above 25 knots and things get interesting, some foils are just more prone to it than others. So first try giving the foil a really good clean, and see if it makes a difference. I clean my foil before every session.
Interesting, I had the same issue w my new North SF680. On my first session I'd been out in the waves loving the foil and getting to know her. No issues at all. But at the very end I decided to put the pedal down and launch some jumps and as I increased in speed right before my pop, I violently nose dived, total face plant. Repeated the process and it did it two more times. I was guessing that maybe the HA208 stab was a mismatch. But they don't have the SF185 stab in stock right now. I'll clean my mast and wing next session but I keep them pretty clean. And then if it continues I'll try shimming. I push the SF930 to the max w the 208HA stab and have never had this happen. If anything I was expecting breaching to be the problem w the larger stab, it all seems counter intuitive to me. Hmmmm
Here is my take on ventilation. The front wing creates a low pressure area on the upper surface, it is virtually sucked up creating lift, this is how an aerofoil works. The larger the camber of the upper surface the lower the pressure and greater the lift.
But, this low pressure can also suck air downwards along the mast and onto the front wing, instant crash. Pushing a higher camber wing at speed with a dirty or poorly designed mast means plenty of ventilation.
Some masts ventilate more than others, Naish have tried to address it in their new HM mast by narrowing the chord of the mast then widening it just before the fuselage, hopeful of the air leaving the mast before getting to the wing.
Aircraft have used wing fences in the past to help avoid the issue.
Many brands such as AFS, Mikeslab and so on do not suffer from ventilation (it's for sure this is what you experienced). The mast thickness, profile and finish really matters.
I had terrible problems with Axis alu masts. Got rid of the Axis gear. No such problems with AFS.
Having gear that does not ventilate at speed is basic 101 of foils.
