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| Laser 28 - Excellent example of this great design Hamble le rice |
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how moths work? |
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NickA 
Really should get out more 
Joined: 30 Mar 05 Location: United Kingdom Online Status: Offline Posts: 784 |
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 Topic: how moths work?Posted: 10 Feb 21 at 9:49pm |
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It's all in the cam design! Once you're up and flying the wand doesn't much affect the flap. It's a strange system from a control engineering POV relying on a carefully managed non linearity between the wand (height sensor) and flap position. But I'll bet the flaps are still moving when you hit a wave that knocks the wand back far enough.
If you were doing it by electronics and software you'd want to detect average height above waves ( which would need low pass filtering of the wand deflection) then a PID controller to operate the flaps to maintain that height. Seems the moth designers have made a mechanical analogue computer that pretty much does all that. An AC75 does the same with digital computers .. I guess. So yes you could probably make a self stabilising moth that worked out all the settings for you ( more so than the current system does ). Would that spoil the fun? Presumably there will be two foiling streams, the performance oriented hard to sail cutting edge ( moths) and the easy foiling for the masses ( the UFO and TFD etc ), which will probably end up with electronics. Interesting to see if a software controlled boat could be quicker than a mechanical one ( answer= yes judging by AC75s) ... and where that would leave the moths. |
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Javelin 558
Contender 2574 |
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laser193713
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Joined: 13 May 09 Location: United Kingdom Online Status: Offline Posts: 889 |
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Posted: 09 Feb 21 at 1:34pm |
I'm not sure that's going to be the case exactly. The development route will focus on performance for the sailors who can already sail them. I doubt the focus of development will be make it achievable for everyone. By all means it may be that other developments make the boat easier to sail, but I don't think "fly easily" will ever really apply... Having sailed a few moths/foilers, from old early foiling moths, a 600ff, a laser with the foiling kit, a bladerider and a mach 2, there has definitely been a progression made towards easy foiling, but that wasn't exactly hard from the early days. The 600ff was almost impossible to sail because to get windward heel your feet moved away from the wing, and there was just too much sail area to try and depower very rapidly as you started foiling. The laser foiling kit is quite frankly pointless, you can't really VMG foil and it isn't very stable because you are running at such high angles of attack to try to pick the weight up that the foil stalls too easily. The moths have certainly got easier and the foil systems more complex, but with a simpler user experience. Mass market foiling is still never going to really be attainable purely because of the speed, and the deceleration when it goes wrong. Injury risk is a big factor for the general public, the same reason you see people on big downhill bikes but they don't ever go down big stuff. The bikes are far more capable, but the speeds and risks involved with actually doing what the bike is capable of is more than Joe Public will put themselves through, the potential to not make it into work on the Monday morning and the mortgage payments that will suffer as a result prevent that. In short, you could make a fully autonomous foiling boat, but you still might not convince many people to sail it, or to sail it hard anyway...
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Daniel Holman
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Joined: 17 Nov 08 Online Status: Offline Posts: 997 |
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Posted: 06 Feb 21 at 5:38pm |
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End of the day I don't think they have damping because its not needed. The object of the wand system is to manage the flap as the boat transitions up onto the foil (max flap on to flap pretty neutral) and from there, control the ride height of the boat over larger amplitude / larger wavelength waves. little wavelets and chop won't cause that many issues, and on these modern moths (exocet. mach 2, aardvark rocket) even though the wand is moving a fair bit you just don't see uncontrolled heave and pitch response decay, or feel anything when sailing, which is what you would need a damper for, if you use the car suspension dynamics analogy. I sailed a newish exocet year before last, and in a straight line it looks after you, flight seems very stable with no intervention from the helm and I think this is one of the biggest improvements over moths of old. The boat largely foils itself.Apart from in tacks and gybes but no con trol system will do that on the moth foil config with 70% of the toal mass going from one side of the boat to the other!
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Sussex Lad
Far too distracted from work 
Joined: 08 Jun 18 Online Status: Offline Posts: 360 |
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Posted: 05 Feb 21 at 2:26pm |
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Riv
Far too distracted from work
Joined: 23 Nov 13 Location: South Devon Online Status: Offline Posts: 353 |
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Posted: 05 Feb 21 at 2:14pm |
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Remember double de clutching cars without synchromesh?
Now we have all sorts of flawless auto boxes. Anyone can drive them. Same will be true of Moths on the next few years. All the difficulty of the control systems will be designed out and almost anyone who wants to practice the basics will be able to fly easily. |
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Mistral Div II prototype board, Original Windsurfer, Hornet built'74.
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Sam.Spoons
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Joined: 07 Mar 12 Location: Manchester UK Online Status: Offline Posts: 3400 |
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Posted: 04 Feb 21 at 11:02pm |
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Sailing anywhere other than directly before the wind is magic to most people
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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish" |
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Rupert
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Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
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Posted: 04 Feb 21 at 10:12pm |
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I thought the answer was "magic". And if magic is simply science beyond a person's comprehension, then I'd be right.
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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dohertpk
Posting king 
Joined: 28 Sep 12 Online Status: Offline Posts: 172 |
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Posted: 04 Feb 21 at 9:52pm |
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Interesting discussion. It's precisely this level of complexity that makes me think I'll never have the kind of mind needed to own one of these boats!
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dohertpk
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Joined: 28 Sep 12 Online Status: Offline Posts: 172 |
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Posted: 04 Feb 21 at 9:51pm |
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aardvark_issues
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Joined: 24 Jul 05 Location: Weston-Super-Mare Online Status: Offline Posts: 505 |
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Posted: 04 Feb 21 at 1:45pm |
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A few people have messed around with some sort of damping. I've had an inline damper robbed from an RC car to have a controlled amount of slop - other people have just straight up introduced slop in the control systems.
Long story short, it's faster to have more control and ride closer to the height limits than it is to try and engineer out the bouncing you're seeing in the wand. |
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