Opposite: the cockpit and wrap-around screen of the Artemis F50 simulator will be immediately familiar to anyone who has visited one of the racecar ‘sims’ to be found wherever the sport takes place at a high level (fewer boast the fast hydraulics featured here). What is unusual is access; in an F1 team, for example, only the most senior engineers (plus driver…) will ever get to see the simulator at all, most being concealed behind solid walls with coded access. All this in five years (left); if only Olin and Rod Stephens were still here to share some of those masterful insights
recalls Nicholls. ‘Now it is much easier!’ While max rudder elevator differential
The Artemis simulator comprises a
single F50 cockpit for three crew (ie short of the two grinders) mounted on top of a ‘Hexapod’, a six-degrees of freedom motion platform mounted in turn on the hydraulic rams themselves. The platform moves within a range of about 1m, very quickly, in every direction. Three laser projectors beam the ‘environment’ onto a 5m-tall backdrop screen that wraps 240° around the whole set-up. ‘The most innovative part of this plat-
form is the integration of the dynamic boat models and the marine models – our wind field and sea state model – and how they interact with the yacht,’ says Nicholls. ‘We simulate how the waves interact with the foils and how the wind field interacts with the water, which are pretty innovative for a simulator of this type.’ For newbie F50 helms – and all but one
are – the simulator allows you to summon up different levels of complexity with the conditions of your choosing… something that is normally in the hands of Mother Nature. So while numpties (such as this author) are able to go cruising on the boat with pretty much everything switched off apart from the helm, the next steps are get- ting the platform moving and being able to use the twist grips on the wheel to adjust the rake of the leeward foil, thereby alter- ing ride height and trim (crisp graphics depict both the ride height and the loaded foil moving around as it is adjusted). The platform does rock’n’roll as you’d
expect either when you stuff the bows in or you fly too high, at which point the boat gets jittery – all discovered intention- ally, just to test the sim, of course. For the more experienced helm, wing
trimmer and flight controller the F50 controls are almost exactly duplicated on the simulator. The single cockpit is even fitted with duplicate sets on either side to enable sailing on different tacks. Apart from the wheel, a single piece of
rope (the wing sheet) and some of the hydraulic jib controls, pretty much every-
thing else in the cockpit would be utterly foreign to the regular yachtsman: because it comes with a complete new lexicon; because it is a catamaran; because it has foils that move in odd ways; because it has a wing again with unfamiliar controls; and because almost everything is operated by hydraulics operating in a complex combi- nation of ways.
Reality check And finally all those questions you wanted to ask in Bermuda, but would never have got answered… There is some relief that the wheel does
steer the boat. However, there is that pair of motorcycle throttle-style twist grips, which alter the rake of the leeward board thereby altering ride height. Now the F50 has a dedicated flight controller it seems unlikely the helmsman will be in charge of the foil rake – though there are some who did learn to control both in Bermuda. In the middle of the wheel five buttons
operate the rudder functions, in particular the differential between the two rudder elevators – typically the windward one pulls down as the leeward one pushes up, adding huge amounts of righting moment. As previously touched on, one step on
from the AC50 is that rudder differential has increased from 3 to 8° on the F50, possible because its operation is now partially automated. For example, a single button press ‘tacks’ the rudder elevators. Slightly more complex is that the maxi-
mum differential that can be dialled in is now automatically limited according to boat speed to prevent rudder damage. As Nicholls, who has been project leader for both the simulator and the F50 systems, explains: ‘It won’t allow the rudder to see more than a tonne of downforce…’ Although it might seem crazy in retro-
spect AC50 control systems were not per- mitted a boat speed input. ‘In the Cup we had these fancy speed estimator algorithms to try to guess how fast the boat was going based on the rudder angles and so on,’
is usually fastest, this isn’t always the case. For example, it can be eased back in strong conditions or in big waves. ‘You might employ less if you want to calm the boat down or even slow down a bit, reaching or in difficult situations,’ says Nicholls. ‘You can also use it for pre take-off stuff (ie to reduce drag).’ Rudder elevator differential is controlled by ‘+/-’ and ‘rudder neutral’ buttons in the centre of the wheel. The helmsman also has pedal controls
mounted on the cockpit’s inboard side to control board up and board down. These are not as simple as they seem. The first press of ‘down’ unstows the weather board (the board is stowed fully canted to ensure its tip remains clear of the water, and with positive rake to ensure it doesn’t suck down if it is accidentally submerged). The second press then fires the board down with yet more automation to ensure its rake angle (relative to the pitch of the boat) isn’t negative; that again might suck the boat down or simply snap off the foil tip. ‘In Bermuda all the teams used to have a
guy who tried to guess the drop angle and tried to line up the pitch angle… Now it’s all automatic, which is a lot safer,’ advises Nicholls. To lower the board the hydraulic accumulator can be used and when Nicholls says ‘fires’, he means it. ‘A 1-1.5 second drop is optimal, 2 seconds is a bit slow. Flow rate is too much at sub-1 sec- ond.’ You wouldn’t want to be in its way. During the last Cup teams were trying
various techniques for dropping the boards, including letting them free-fall initially at least (thereby saving hydraulic power). ‘To do that your drop angles would be quite negative and at the bottom it could get quite hairy and you could damage the board if you weren’t careful…’ says Nicholls. The hydraulic accumulators are a legacy
of the AC50 and can be used on any function the crew so decides. However, Nicholls expects them only to be used for board drops as the new battery-powered hydraulic pump is adequately fast for all other functions. Reassuringly the ‘board up’ does work in reverse of ‘board down’, the first tap canting the board and the second raising it, positive rake dialled into the board to help it fly upwards. As with the rudder differential, the
‘max’ setting for the main foils is with zero cant but, similar to easing off rudder dif- ferential, so cant can be dialled into the main foils. This puts the foil into a more
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