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661 F'n Saint

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  1. Boink

    Boats and foils comparison

    In principle I agree with your thinking - but remember that we are talking about a flap that is filling a 4.0m span. There is a realistic possibility that such a flap could be twisted with more deflection in the middle and less at the outboard tips, or freakier still, just twist where more effect would be greatest felt...... I have wondered about this since they seem to have coalessed around flat or flatter foils with less anhedral. At its most extreme could they be inducing a moment of lift that is no longer symmetrical to the foil but outboard of the foil arm attchment point? Thereby increasing RM beyond rule intentions. I am sure that the foil arm will have a safety factor - it's more whether the layup could resist the torsion and twisting that might induce flutter or other instability. Food for thought if you are thinking outside the box. May also further compensate for trying to run an overall smaller foil - which has inherent advantages in other areas........
  2. Boink

    Boats and foils comparison

    ^^^^^^ Bear in mind, whilst machining a new foil and flap, or more likely a flap only IS more straightforward from a machined billet and certainly faster production wise; IF the original architecture of the foil arms and/or foil and/or flap, and even the global displacement pf the whole platform was from a composite contruction, the change in material alone may restrict what the teams can do overall........ The total +/- allowances in displacement both component and globally, are relatively small to be of consideration. This alone would be a valid reason not to Camouflage a steering wheel........ Look how Blair has De-Mulleted........ Enforced Team Circumcision will be up next.........
  3. Boink

    Boats and foils comparison

    Serious question here. Does your model attribute the sizing and distribution changes as the teams go from full size main and CZ through to Code 1 jib and then down through the mainsail sizes and their most commonly partnered smaller jib sizes? For TNZ B1 seemed to have modes of nose down vs flat that were generally attributed to upwind in full power vs downwind. B2 seems to be designed around a more consistent hull angle of flight to maintain the skeg profile parallel to the water surface and chase those aero gains full time - and in doing so seems to be much closer to water surface in all modes. What rig efficiancy gains have they uncovered that they have been so willing to push down this design path? Does this small perceived range of movement and less mode changing enable a shorter and therefore lighter Rudder to be run than before? If, as suggested this more limited range of flying envelope is happening, then we can at least theorise that this is the "sweet spot" where gains are to be found - giving endplating and other such aero benefits. If you are now self constrained to a smaller range of flying envelope - can you further drill down on the features that are optimum in those moments and lose the ones that might have been desirable before (e.g. large range of flap articulation - possibly thought of as a must have in early design conversations - now seen to be much less desirable as they are leading to needing actuator motors and mechanical link systems that are unecessarily bulky in steady flight mode) I have read somewhere that the aft positioned flap behind the foil arm mechanism allows one continuous flap across the whole rear edge of the wing - eliminating two flap joins (Starting and stopping around the midline Bulb) that need articulation and drive and all the associated drag that those physical breaks come with. Food for thought....... Nothing comes without compromise. But if the Team has decided to not build a forgiving platform; but one that takes borderline brilliance and skill just to get into flight and must therefore be kept airbourne at all costs - but then by having done so is 1.5-2.0 knots faster than the other 3, then they will still look like superheroes even if they cannot engage or win a start. The team have a well documemented history of carving their own path. They have the perfect poker faces and enough natural hiding places within these deck turrets to not have their body language or expression read of what is really going on, to be communicated....... though the other 3 teams probably dont want to see the Shit eating grins that they must be developing if last week was any sort of indication. Fascinating stuff over the next 3 months.
  4. Boink

    The definitive Ground Effect thread.

    Are your calculations also from the same mind that drew the sailboat on your Avatar??? Asking for a Confused Friend......
  5. Boink

    Emirates Team New Zealand.

    Your original question only asked about ETNZ, why the rewrite/reframe now......? Have you considered that the Italians have an entirely different design team who are not ETNZ's design team? Is it possible that the Hanbags have rigged their Jib in a I14 or Model Yacht manner? (Where the jib seet leads forward back to the stem thereby allowing self-tacking ability and then play the Jib slot by actuating the Jib Track) Does @weta27 or other reliable eyes on the scene bear testimony as to how they tack their headsail. I have not studied the actions of this boat.
  6. Boink

    Emirates Team New Zealand.

    Why are you considering the Mainsail as a single entity? Hint - The actuality is that is it is working in concert with the Jib........ (Furthermore, your assumptions indicate significant and unrealistic twist between 4 and 6% stations)
  7. Boink

    Emirates Team New Zealand.

    Think about the effects of geometry if you were to move the that aft turning block up to within say a metre behind the transverse jibs tracks. Everytime you wanted to inhaul or release the jib sheeting angle along those tracks, you would also need to compensate the length of jib sheet in unison or bugger up the twist profile of the jib. This way, they can alter the jib AOA up and down the Jib track rapidly and repeatedly without havig to alter the Jib Sheet at all...... Simples. The Bigger question is about those deck led rams off the Mast bracket that lead to the mainsail clew. We know that Mast rotation is acheved underdeck as no other boat has this arrangement above deck. Furthermore it is proposed that it is connected to the mainsail clew (correct) and is adjustable in length (also correct - they are long travel rams at the mast bracket end). I am wondering about what happens at the Mainsail clew end of the mechanism. We know that there is a Diagonal Box Batten system that starts at Deck Level - passes through the Mainsheet ram attachment point and continues up in that Diagonal path to what can be considered the "Clew Corner". My thinking is that these rams either straighten or relax the windward skin to separate it from the leeward skin giving many more profiles and camber options - by turning around a turning sheeve it the lower most section of that Diagonal Batten Box and onto the rear end of the Deck sweeper Batten. And/or it also induces a Vang effect upon that Diagonal Batten Box structure - whic pivots in a see-saw action around the Hyrdraulic Ram Attachment point. Thereby, as the deck sweeper rams are tensioned it will effectively vang the leech of the windward mainsail - independent of the mainsheet tension. I can think of times when keeping these two effects independent of each oither would be beneficial. The sail loads and adjustability through that take off phase must be highly variabale and very demanding. There is a whole cats cradle of control lines going on at the Clew end - so I can forgive the odd wrinkle to what is otherwise a very effective solution. Thoughts from the Non-Peanut Gallery????
  8. Boink

    Emirates Team New Zealand.

    Clearly that Helicopter has been taking cues from all this AC development cycle. It's nose down, arse up, low to the water, seeking Ground Effect and a Wanna Be Ekranoplane with a Lotus '79 inspired black paint job. "Utterly conclusive proof." an anonymous Black Billed Gull was quoted as saying before rushing off to swoop on an unsuspecting child with Hot Chips.
  9. Boink

    Emirates Team New Zealand.

    FIFY: Hiltz! Cooler. 3 days...... (Uncredited flunky actor tosses hero a Baseball Glove and Ball) Cue, evocative Whistling Tune.......
  10. Boink

    The new sailing twin skin setup

    I hear you. Some smart cookie will run the numbers - but that will be post Cup. I will say that I have always supported the concept - as being a much more manageable solution than solid wings - and give these 2 or 3 more cup cycles or development and iteration and you will see trickledown into other boats. At that point, the comparison will be entirely moot.
  11. Boink

    INEOS Team GB

    You, nor your army of Cheese eating surrender Monkeys, could have overcome him back then. He was Big Ben back then, who you clearly have never met, and he would have chewed you up and spat you out. I don't condone his actions but at least he is passionate about what matters and the Media boat was well out of order. You Froggies used to understand and congratulate Passion. Shows what an antiseptic and sterile world we live in today. To Paraphrase (in an outrageous French Accent) "Ben Farts in your General Direction.....!"
  12. Boink

    The new sailing twin skin setup

    The AC 75's will monster the AC 50's on VMG becasue of the speed of the turns that they are achieving. Refresh your memory of how an AC50 tacks then come back. This was talked about 6 or more months ago when TNZ issued a Video showing multiple gybes into a leward mark which was rounded smartly and then immediately tacked away - all with little appreciable reduction in boatspeed. It's not a Soft vs Hard wing issue - its the entire paradigm change of the package.
  13. Boink

    The definitive Ground Effect thread.

    Not sure where you are going with all of this. It is probably easier to consider these Hydrofoil craft in Ice Boat terms. Go back to your High School Vector Diagrams to better consider what you are ultimately trying to achieve - namely maximise Rig Power, orientate Rig power by minute increments towards a forward facing direction and yet minimise side slip (leeway) to allow the Forward Thrust to be maximised. Then get creative as to how to minimise drag...... But if you dont maximise RM to resist the large sideways component of Rig Thrust then you will never be as fast as the competition - so RM is vital. Not when to get it "dead" right you compromise all the other things that are really driving the show. That is a classic case of being Penny Wise and Dollar Dumb..... There is talk elsewhere about ratios of TWS to outright Boat speed - some claiming as high as 3.6 or 3.7 multiples of windspeed translating to velocity. So why would they chase so hard to gain a Ground effect of Lift when you are almost immediately trying to reduce global lift becuase to reduces overall RM as discussed immediately above? Simply put, they are chasing the best aero solution - highest rig efficiency requires low flight height to reflection plane and preservation of trying to separate high pressure from low pressure - whether that be undre the Hull or across the deck - that concept is not disputed and widely accepted. So why chase Ground effect that will compromise those keenly sought effects? With respect to AM - yes they are slippery - but so are all the boats - but I believe their hull/skeg camber profile is still not as extreme as say TNZ or Inoes - its as if the designers have said - well touchdowns and take off still need consideration so we will go less extreme. The others have gone "all-in" to use a poker analogy...... I like the deck treatment used by TNZ to both encapsulate the crew and provide a great piece of wind tunneling for the sails to sit within. The anorexic skinniness that the whole hull provides for it to slice the air must count for something. The others are slippery too, but are more towards the slim, natural or plump status depending on where your allegiances or favouritism sits. It even has the protruding Hip Bones that Skinny girls display in their Bikini Bridges..... Look it up (Discreetly if you are at work). Just for the Record, I dont have carnal desires for any of these Boats......... My Heart remains firmly with Scarlett and Miranda!
  14. Boink

    The definitive Ground Effect thread.

    Can we just stop revisiting this Debunked and Fallacious concept. There is no steady state that these boats operate within for them to chase this as an aid, that would out do the refinement that would be compromised elsewhere to make it actually happen. The Hull is too long and narrow to create a substantial effect. These are not Piper Cherokees or whatever. Nor are they Jet Fighters. And certainly are not Hovercraft or Ekranoplanes. All Ground effect concepts whether seeking lift or downforce are much squarer in planform and utilise downtips, or skirts, or fences to maximise the pressure differential needed to achieve the lift. By the time these hull shapes could be contributing a lifting force (i.e. high hull speed) they are either actively seeking increased RM (downforce to the challenged here) or are butting into the window of foil cavitation. So a Lifting Hull is the last scenario that is being sought. Whenever Lift is generated - remember that it comes at a price of drag. Lowest Drag solution will win this Cup because it will maximise VMG. Discuss VMG gains instead - I implore you..... The Keel/Skeg/Bustle (I dont care what term is used) - is to endplate the whole rig to a reflection plane status which boosts the K value of Rig efficiency - it also deepens the I-Beam effect of the hull making it a stiffer global platform to reduce hull flex. Bow down allows wider foil geometry to be achieved with what is otherwise a simple and resticted foil articulation. Bow down also allows the Jib and mainsail base to "see" cleaner and scoop more air. The ETNZ B2 has clearly been designed to allow as clean an airflow around the deck structure as possible - lower drag improves Lift Coefficient. The slim profile that the deck surface and hull undersides allow for best possible drag characteristics. No Flat (vertical) transom removes another drag point. The full length Skeg allows the transference of Runner loads into the hull more efficiently. The Skeg may also contribute leeway resistance at take off. The Horse Blinkers that have been added to the Foil Arms are I suggest both Spray Control but possibly also extra Lateral surface for leeway resistance whilst immersed, at that critical point of take off where loads are rising exponentially yet a slippery hull aids and assists with acceleration and lift off. I cannot find any reason why thy cannot be assymetrically shaped to assist in this role as they fall outside the Foil Control box which is where symmetry is required under the class rules. Study the take off video sequences, there is no flow of air under the boat whilst it is still floating - so the platform is not assisting in providing any lift. There is only a few seconds of this eagerly claimed Tunnel effect, but it really does not add any sustained or steady state effect..... The T profile that the Hull presents allows easier water release and non catastrophic touchdowns as well as enplating of the whole platform to the waters surface. IF, the hull structure was creating lift - there would be additional interference drag by the competition of effects that the deck structure was trying to create by endplating the sails and creating distinct high and low pressure zones to windward and leeward of the sail skins, thereby lowering the Rigs efficiency. Not a situation that would be actively encouraged or sought. As, written about elsewhere - the acceleration of the boat speed is so rapid that by 15 knots of windspeed you are rapidly approaching the Boat speed limitations caused by Foil cavitation. So to propose that these boats actively seeking Ground effect lift over an 8 to 8.5 knot windspeed increase range (6.5 or 7 to 15 knots of windpeed) is just too far fetched...... The reverse is more likely - with additional RM sought from the orienation of the hull to at least fly neutral or possibly gain RM - but certainly to wash out any lift that that the platform is generating. Windward heel is widely witnessed. It throws the whole weight of the rig into a beneficial pose. The Foils become slightly unweighted, requiring less lift, and associated drag. The heel of the boat (upwind) allows the boat to crab to windward as the heel axis is diagonal across the direction of movement. Streamlining seems to be the mantra of both ETNZ and LR, with ETNZ a half generation further down the development evolution. Impressive they are. Hovercraft or Ground Effect vehicles they are not........ Please feel free to contradict everything here with Piper Cherokee anecdotes, Private Pilot Licence Snobbery and Fighter Jet stories. Do not forget to add in lots of Lotus 79 pics and Wright Brothers parallels. You are all unique and valued and highly paid members of Team New Zealand Design Inner sanctum. And Dan is completely Lost, without you all....... Miranda Kerr and Scarlett Johannson both need their Massages with Happy Endings - Do excuse me
  15. Boink

    Australian Sailing

    Courtesy of Australia Post? - or another Parcel Handler?