Mizzmo
Anarchist
Link?
18' Whisper Production Foiling Cat
- Thread starter Doug Lord
- Start date
Mizzmo
Anarchist
Doug, good point. I guess I need to get off the forums and do some actual work. Not that I want to build anything... I like actually sailing too much
Thank you Phil for your analysis of Moth's foils development, it makes the whole discussion much more interesting
I wonder if using vertical acceleration could be an alternativve to wand for flap control.
I mean, the main foil push upward, if the stopping mecanism is a silent-bloc. and the little vertical movment of the foil under load change could be used to activate the flap.
The whole mecanism would be inside the strut, with just a pin or lever-arm to be connected with the foil casing.
Of course, it addresses only change in foil's lift, no high control
Cheers
W
I wonder if using vertical acceleration could be an alternativve to wand for flap control.
I mean, the main foil push upward, if the stopping mecanism is a silent-bloc. and the little vertical movment of the foil under load change could be used to activate the flap.
The whole mecanism would be inside the strut, with just a pin or lever-arm to be connected with the foil casing.
Of course, it addresses only change in foil's lift, no high control
Cheers
W
F18 Sailor
Super Anarchist
Awesome!!!! Any chance of setting up a sea trial at the Annapolis Boat Show? My (highly experienced) F18 skipper (she's cute too
) and myself would like to go for a spin. We've both sailed foiling moths before and I have race time on C-board+t-foil A's. We can send it and keep it in one piece Oh, and we live here so can help with logistics/setup etc.
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F18 Sailor
Super Anarchist
We take apart F18's ALL THE TIME for transport as a fleet-it's much easier to load 6 F18's on a trailer taken apart, and it doesn't add too much work on each end for re-assembly.
The notion that the windward foil in a 2m wide cat will produce active downforce seems to me to be entirely impractical. It would need to be extremely highly geared and at the nominal ride height be producing down force rather than up force, so it would require some alteration of gearing between windward and leeward configuration.
If the boat weighs 80kg with say 150kg of crew, that means each foil needs to go from creating around 250kg of lift when on the leeward side to some amount of down force when on the windward side while remaining at the same height above the water. And as Phil says, for every extra kg of down force, the opposite foil must produce an extra kg of lift. All while the boat stays more or less flat, so zero input through the wands. Nice feat.
Now introduce waves, so the wands are getting entirely spurious input. Wands are very simple devices, they just sense distance between a discrete point and the hull, they don't measure attitude, pitch or vertical velocity. That's what makes flapless foiling like the A Class are developing important.
As for Off Your Rocker, it would be interesting to see that experiment with a full width boat and modern foils rather than Ts with wands. But I think it cost the better part of 7 figures so not something that's easily repeated.
If the boat weighs 80kg with say 150kg of crew, that means each foil needs to go from creating around 250kg of lift when on the leeward side to some amount of down force when on the windward side while remaining at the same height above the water. And as Phil says, for every extra kg of down force, the opposite foil must produce an extra kg of lift. All while the boat stays more or less flat, so zero input through the wands. Nice feat.
Now introduce waves, so the wands are getting entirely spurious input. Wands are very simple devices, they just sense distance between a discrete point and the hull, they don't measure attitude, pitch or vertical velocity. That's what makes flapless foiling like the A Class are developing important.
As for Off Your Rocker, it would be interesting to see that experiment with a full width boat and modern foils rather than Ts with wands. But I think it cost the better part of 7 figures so not something that's easily repeated.
Doug Lord
Super Anarchist
- Thread starter
- #72
I definitely don't think using downforce on the Whisper is practical or desirable-but how do you prevent it with a wand system? The only way I see is that if both guys are on the wire and the thing heels even a little they'd need to depower. Otherwise there would be downforce from the windward foil IF the wand has complete freedom of movement and enough force is available to hold the flap up.
Rave: it would be interesting to know the story behind that picture-could be a set up issue where the shock cord on the windward foil didn't have enough tension and the foil couldn't develop downforce as a result.
In "normal" Rave foiling the water pressure against the wand holds the flap down for lift when required. But for downforce, it's the shockcord that holds the flap up-not enough tension=little to no downforce.
Rave: it would be interesting to know the story behind that picture-could be a set up issue where the shock cord on the windward foil didn't have enough tension and the foil couldn't develop downforce as a result.
In "normal" Rave foiling the water pressure against the wand holds the flap down for lift when required. But for downforce, it's the shockcord that holds the flap up-not enough tension=little to no downforce.
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There we go again.
Just gloss over the evidence that blows you and the boat literally "out of the water" - and try to say that it is a set up issue.
This is why your unwavering and inflexible attitude grates with so many people.
We understand that we are in an imperfect world. There is no magic bullet and compromises are a necessary outcome.
Your black and white approach that stipulates right from wrong, good from bad is just nonsense.
Every system needs to be appraised and considered from a holistic sense. It may work in 8 knots of flat water - but 9 knots & chop might be its undoing....
What is good for lift off at 12 knots of boatspeed is probably limited to mid twenties of peak velocity.
What is good for steady state flying on a reach is probably sub-optimal going upwind or deep downwind.
One trick ponies are of interest for only a short period of time and will ultimately be superseded by its two and three trick cousins....
So to claim that something is 100% successful is a 100% certain to be found out.
Just gloss over the evidence that blows you and the boat literally "out of the water" - and try to say that it is a set up issue.
This is why your unwavering and inflexible attitude grates with so many people.
We understand that we are in an imperfect world. There is no magic bullet and compromises are a necessary outcome.
Your black and white approach that stipulates right from wrong, good from bad is just nonsense.
Every system needs to be appraised and considered from a holistic sense. It may work in 8 knots of flat water - but 9 knots & chop might be its undoing....
What is good for lift off at 12 knots of boatspeed is probably limited to mid twenties of peak velocity.
What is good for steady state flying on a reach is probably sub-optimal going upwind or deep downwind.
One trick ponies are of interest for only a short period of time and will ultimately be superseded by its two and three trick cousins....
So to claim that something is 100% successful is a 100% certain to be found out.
Downforce is prevented by creating a system that doesn't allow it to occur, e.g. Moths. There is no rational reason to believe that a wand/flap system must create downforce by some mechanical axiom.
It's a response to your assertion that there is no stability issue with foilers that use downforce. How or why it happened is irrelevant, it happened, contrary to your assertion.
You can see the ventilation drop in the following video at about 1:06 (there are many others, but that's the only one that isn't cut before the splash), flying the foil is at about 2:07. Again, cut before the inevitable crash (in comments the poster says "The pilot that went flying had a soft landing…"). It's been on YouTube since January 2007.
https://www.youtube.com/watch?v=CRTBYyNsmic
Doug Lord
Super Anarchist
- Thread starter
- #77
This is how it's supposed to work. Again, water pressure against the wand moves the flap down, but for downforce only bungee tension holds the flap up. If there is not enough tension or if it is rigged incorrectly there will be no downforce when you need it:
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You're truly clueless Doug. You know all those videos showing Moths going down the mine? That's what happens when the main foil ventilates and gives zero lift. Now imagine what would happen if they generated down force.
Also try to work out the design issues inherent in a flap that can overcome the lift of a foil with about 2.5° AoA and generates about 100kg of lift in neutral. Moths are also quite capable in big waves of sailing quite some distance with the wand clear of the water in the fully forward position, there are plenty of videos on the YouTube if you care to look. They absolutely would not do that if it caused the main foil to generate downforce.
Lastly, the rudder has only very small adjustment of lift and is about neutral, so if the main foil goes negative you now have a lever with the equivalent of a 100kg weight plus whatever downforce the foil is generating on a 1.5m arm. Not much is going to save you there.
I'm putting you back on ignore.
Also try to work out the design issues inherent in a flap that can overcome the lift of a foil with about 2.5° AoA and generates about 100kg of lift in neutral. Moths are also quite capable in big waves of sailing quite some distance with the wand clear of the water in the fully forward position, there are plenty of videos on the YouTube if you care to look. They absolutely would not do that if it caused the main foil to generate downforce.
Lastly, the rudder has only very small adjustment of lift and is about neutral, so if the main foil goes negative you now have a lever with the equivalent of a 100kg weight plus whatever downforce the foil is generating on a 1.5m arm. Not much is going to save you there.
There you go, asserting that systems that generate negative lift don't have issues.
You mean the bit where it's skimming along happily? That's clearly a cut from a different event (it appears to be a different boat) and whatever the setup is, it's not causing any issues. The maker of the video claims to be a reseller, so if they don't know how to set the thing up, who does?
I'm putting you back on ignore.
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DouGiE - you write:
".....I have hundreds of hours on a Rave to back that up(and over 1000 hours on test models that work like a Rave)."
Yet by your own admission you have achieved 15 seconds of sustained flight.
The remainder being slow, lurching and uncontrolled hip hop dancing.
Great success rate....
You say that you are multi-coloured - really?!?!
You haven't got past the primary colours..... much like your sense of humour, dress sense and hygiene regime; it is struck in first grade (remedial level).
Certainly your grasp of maths reflects your success of hydro-foiling 100%.
Go stick your fingers back in your ears, and put your head back in the sand or back up your @rse - you are a modern day King Canute - Look him up...... You might actually learn something. But I doubt it......
".....I have hundreds of hours on a Rave to back that up(and over 1000 hours on test models that work like a Rave)."
Yet by your own admission you have achieved 15 seconds of sustained flight.
The remainder being slow, lurching and uncontrolled hip hop dancing.
Great success rate....
You say that you are multi-coloured - really?!?!
You haven't got past the primary colours..... much like your sense of humour, dress sense and hygiene regime; it is struck in first grade (remedial level).
Certainly your grasp of maths reflects your success of hydro-foiling 100%.
Go stick your fingers back in your ears, and put your head back in the sand or back up your @rse - you are a modern day King Canute - Look him up...... You might actually learn something. But I doubt it......
