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roll stability of foils?

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lovethepirk
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Re: roll stability of foils?

Postby lovethepirk » Thu Aug 17, 2017 10:51 pm

gmb13 wrote:
Wed Aug 16, 2017 6:38 pm
What most people forget is that the foil is not sitting still in the water. It is flying at speed, and the pull of the kite is trying to pitch the foil forward. This makes the tailplane or stabiliser more important than on a plane driven by engines. The Tailplane is preventing the Front Wing from pitching forward and also resisting the yaw (especially on back wings without a yaw stab fin) and roll. If you get the chance try small and larger back wings back to back, and you will see the difference. When you switch out front wings (for example Zeeko Freeride wing to Speed wing) you will notice no huge amount of change in roll stability. But if you reduce the angle of the tailplane (shim) you will have a major change.

But hey. What do I know about foils? ;-)

--
Gunnar
Love your insight, thanks. Amazing the dynamics at play when kiting :thumb:

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Re: roll stability of foils?

Postby grigorib » Mon Sep 18, 2017 4:31 pm

Pedro Marcos wrote:
Thu Aug 17, 2017 7:07 pm
...all the Moses wings now , and the 550 is my overall favourite, I use the others in more specific situations.
Do you think you can help me with below questions, please?
- how do you think GW 545 (from Ghost Whisper) wing compares to 548? Would 548 be more freeride, lower takeoff speed, lower lowend I'm looking for or they're not much different?
- I felt on 330 stabilizer and 42" inch mast a lot of force from the board to stay horizontal which makes it harder to edge initially. Is it primarily because of long mast or because of winglets on 330? Would changing to 325 stabilizer result in more playful setup or I need to ride shorter mast for that?

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Re: roll stability of foils?

Postby TomW » Mon Sep 18, 2017 6:41 pm

It appears the rear wings on the GW are similar or same as Moses rear wings. Go down to the thread on Moses wings.
But basically I have both 325 and 330 rear stabilizer wings. 325 is considerably less roll stable, less yaw stable and generates less downward lift, feels better at speed than 330.
That said, I've gone back to 330 as I'm learning transitions.
I've learned that I have to yaw to turn, not edge.

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Boards: Spleene RIP 37, Spleene Door 59, Flysurfer Flydoor5 XL, MHL Lift 2013, Slingshot Ghost Whisper 42"/545/328, Moses 71cm/548/325, Lift 150/36", Slingshot Dwarfcrafts 42"/54", Slingshot Coupe 6', Ocean Rodeo Mako 135, MBS Comp 95x
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Re: roll stability of foils?

Postby grigorib » Mon Sep 18, 2017 6:58 pm

TomW wrote:
Mon Sep 18, 2017 6:41 pm
It appears the rear wings on the GW are similar or same as Moses rear wings. Go down to the thread on Moses wings.
But basically I have both 325 and 330 rear stabilizer wings. 325 is considerably less roll stable, less yaw stable and generates less downward lift, feels better at speed than 330.
That said, I've gone back to 330 as I'm learning transitions.
I've learned that I have to yaw to turn, not edge.
I've been going through these threads but what I understood that 330 keeps foil vertical well and that's what I'm struggling with in lighter winds during starts, it's much harder to edge initially. That might be because of long, 42" mast too but I don't know which is a stronger factor here and if shorter mast or 325 stabilizer would help.

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Re: roll stability of foils?

Postby Pedro Marcos » Mon Sep 18, 2017 7:49 pm

grigorib wrote:
Mon Sep 18, 2017 4:31 pm
Pedro Marcos wrote:
Thu Aug 17, 2017 7:07 pm
...all the Moses wings now , and the 550 is my overall favourite, I use the others in more specific situations.
Do you think you can help me with below questions, please?
- how do you think GW 545 (from Ghost Whisper) wing compares to 548? Would 548 be more freeride, lower takeoff speed, lower lowend I'm looking for or they're not much different?
- I felt on 330 stabilizer and 42" inch mast a lot of force from the board to stay horizontal which makes it harder to edge initially. Is it primarily because of long mast or because of winglets on 330? Would changing to 325 stabilizer result in more playful setup or I need to ride shorter mast for that?
Ive never ridden or actually see a Ghost Whisper hidrofoil, but from the photos i can find it seems the front wing its much more "speed" oriented then the moses 548, so i think there is no comparison possible, the moses 548 should be a much easier/slower wing with much more lift.

The longer mast makes everything slower, you should not compare wings with diferent mast lenghts, because the mast also have big role. The 325 sta works well with the longer mast, it makes the foil much more reactive and less roll resistant, which its great to carve around and do tight turns, but foot changes while foiling also become harder if you are still in the learning phase.

grigorib
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Boards: Spleene RIP 37, Spleene Door 59, Flysurfer Flydoor5 XL, MHL Lift 2013, Slingshot Ghost Whisper 42"/545/328, Moses 71cm/548/325, Lift 150/36", Slingshot Dwarfcrafts 42"/54", Slingshot Coupe 6', Ocean Rodeo Mako 135, MBS Comp 95x
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Re: roll stability of foils?

Postby grigorib » Tue Sep 19, 2017 1:53 pm

Pedro Marcos wrote:
Mon Sep 18, 2017 7:49 pm
grigorib wrote:
Mon Sep 18, 2017 4:31 pm
Pedro Marcos wrote:
Thu Aug 17, 2017 7:07 pm
...all the Moses wings now , and the 550 is my overall favourite, I use the others in more specific situations.
Do you think you can help me with below questions, please?
- how do you think GW 545 (from Ghost Whisper) wing compares to 548? Would 548 be more freeride, lower takeoff speed, lower lowend I'm looking for or they're not much different?
- I felt on 330 stabilizer and 42" inch mast a lot of force from the board to stay horizontal which makes it harder to edge initially. Is it primarily because of long mast or because of winglets on 330? Would changing to 325 stabilizer result in more playful setup or I need to ride shorter mast for that?
Ive never ridden or actually see a Ghost Whisper hidrofoil, but from the photos i can find it seems the front wing its much more "speed" oriented then the moses 548, so i think there is no comparison possible, the moses 548 should be a much easier/slower wing with much more lift.

The longer mast makes everything slower, you should not compare wings with diferent mast lenghts, because the mast also have big role. The 325 sta works well with the longer mast, it makes the foil much more reactive and less roll resistant, which its great to carve around and do tight turns, but foot changes while foiling also become harder if you are still in the learning phase.
I've got a definitive answer - GW FR 545 wing of Ghost Whisper is 558 wing with rounded and shortened wingtips. The stabilizer measures 330mm and has winglets so it must be Moses 330 stabilizer.

From all I've read - that a very stable, speed oriented combination. I'm in search for low-end, low take-off speed setup specifically.

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Re: roll stability of foils?

Postby Pedro Marcos » Tue Sep 19, 2017 2:01 pm

I've the 558, it's not a race wing , it still have plenty of lift. It's very good overall but not so easy has the 550, it requires more minimum speed and allows less rider mistakes.

For me 550 it's the most all around of the Moses wings , even if they call the 558 the all around.

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Re: roll stability of foils?

Postby TomW » Tue Sep 19, 2017 5:36 pm

grigorib wrote:
Mon Sep 18, 2017 6:58 pm

I've been going through these threads but what I understood that 330 keeps foil vertical well and that's what I'm struggling with in lighter winds during starts, it's much harder to edge initially. That might be because of long, 42" mast too but I don't know which is a stronger factor here and if shorter mast or 325 stabilizer would help.
I don't really understand what your difficulty is. You're saying you are struggling with lighter wind starts? You shouldn't edge during lift off. Once you are out of water and board is moving Keep the board flat, gain speed and lift off. once flying you can tilt board to windward slightly, but remember foil mast and you body " are one and should align vertically ".

grigorib
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Local Beach: Clinton Lake, IL; Ogden Dunes, IN; Michigan City, IN; South Haven, MI; Tawas, MI; OBX; SPI
Gear: Kites: Slingshot Rally 8m/11m, Slingshot Turbine 9m/15m, Flysurfer Speed4 10m, Best Kahoona 11.5m, Peter Lynn Venom II ARC 16m
Boards: Spleene RIP 37, Spleene Door 59, Flysurfer Flydoor5 XL, MHL Lift 2013, Slingshot Ghost Whisper 42"/545/328, Moses 71cm/548/325, Lift 150/36", Slingshot Dwarfcrafts 42"/54", Slingshot Coupe 6', Ocean Rodeo Mako 135, MBS Comp 95x
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Re: roll stability of foils?

Postby grigorib » Tue Sep 19, 2017 5:49 pm

TomW wrote:
Tue Sep 19, 2017 5:36 pm
grigorib wrote:
Mon Sep 18, 2017 6:58 pm

I've been going through these threads but what I understood that 330 keeps foil vertical well and that's what I'm struggling with in lighter winds during starts, it's much harder to edge initially. That might be because of long, 42" mast too but I don't know which is a stronger factor here and if shorter mast or 325 stabilizer would help.
I don't really understand what your difficulty is. You're saying you are struggling with lighter wind starts? You shouldn't edge during lift off. Once you are out of water and board is moving Keep the board flat, gain speed and lift off. once flying you can tilt board to windward slightly, but remember foil mast and you body " are one and should align vertically ".
Well, I was one with my MHL 2013 and I could edge right off on a first dive and be on the foil. How else would you start on shallow where depth is less than mast length?
I still align with mast line but Ghost Whisper with 106cm mast / 545 (558) and 330 wings just resists that roll pressure a lot and I'm wondering what would help it the most - using 91cm mast or 548/550 wings or 325 stabilizer.
I fail to understand why foil manufacturers abandoned that playful beauty of immediate "take off" as if everyone on foil is racing...

TomW
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Re: roll stability of foils?

Postby TomW » Tue Sep 19, 2017 6:42 pm

Ah, now I get it. I'm not experienced enough using different mast length, or taking off that way. I'm still doing the get up out of water, gain speed and lift off stage. Sometimes I pop right up on foil from water, but it's kinda accidental.
I'm using 93cm mast ( strut) , Moses 550+330 and it takes some water speed or kite lift with some speed to get onto foil. My guess is your front wing needs more lift at low speed to do what you want.


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