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how moths work?
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Daniel Holman View Drop Down
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    Posted: 06 Feb 21 at 5:38pm
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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laser193713 View Drop Down
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Posts: 889 		Post Options Post Options   Quote laser193713 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Feb 21 at 1:34pm
Originally posted by Riv

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.

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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NickA View Drop Down
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Posts: 784 		Post Options Post Options   Quote NickA Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 21 at 9:49pm
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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