Boats and foils comparison

[Chimp too]

On the foil bulbs, the mass has to go somewhere. Maybe the bulb solution is a lead bulb and carbon foils, whilst the no bulb option is full tungsten steel foils to get the density up throughout and avoid the extra volume of lead by distributing the denser material throughout. Expensive solution 

 

[Basiliscus]

Rocket pods? Maybe to help with flow at the tips of the flaps? But then why only on the bottom?...

My guess is they house actuators of some kind.

 

[barfy]

My guess is they house actuators of some kind.

I respectfully say, what an un elegant solution when they have managed no gap hinges. The big bulb might be good place for hiding the needed bits and bobs?

 

[Lakrass]

For the pleasure of speculation, if I was willing to foils as soon as possible, I would chose:

- Orca for flat water

- Sardine for little chops

- Flipper for waves

Now, at speed and foiling, I think I would prefer the Orca hoping to get a small air cushion between hull and water.

Playing the speculation game as well...

In displacement mode, I choose Sardine
In fully foiling mode, Orca
In foiling mode with short contact with water, Flipper

About the various foils we have seen, it might be dictated by which stage of their program they are in. Let's not forget AM and LR had surrogates to get time testing the concept. ETNZ didn't and might want to start foiling in less wind and maybe not achieve as high speed with the first boat and set of foils. All 3 should cover most sailing conditions and speed for design input into next boat (maybe ETNZ lacking a bit for supercavitation if those torpedo are addressing that).

Looks like all teams are well into the game right now and love the different designs approach. We are just missing more weta27 in US, Italy and UK...

 

[Kiwing]

for getting onto foils first I choose flipper

for top speed I choose Orca

for VMG I choose flipper

for displacement mode VMG under flipper take off speed I choose sardine

For maneuverability in Displacement mode under flipper take off speed I choose Orca

 

[RobG]

I respectfully say, what an un elegant solution when they have managed no gap hinges. The big bulb might be good place for hiding the needed bits and bobs?

If you only have an actuator in the bulb, that's a long stretch of tube/rod to accurately control the torque at the far end of the flap. If there's an actuator at both ends, the torque issue is halved (in my simplistic view).

 

[phill_nz]

ok just to throw another parameter in

for takeoff distance

flipper

flamingo

flopper

i have not yet seen

boudicas revenge

 

[inebriated]

So, I see a shit load of drag going on, on two of the foil versions above.

The torpedoes 'may' be more stable - but are they faster? Not likely.

we all learned last cup that stability on foils is faster than just straight "speed"

 

[inebriated]

YoU foRGoT StaRS AnD STriPeS

 

[minimumfuss]

They sure look like airplane wing actuators in miniature. Are there any actual flaps visible? can you deform a whole foil surface by stressing it with such a device, so no separate flap? . Angles required aren't huge. At least we get to wildly speculate since they're visible. 

 

[Monkey]

To really get lift (like a wing) the underside would need to be dead flat to generate pressure differential. Their hull is still quite round which leads me to believe it's more about drag reduction than lift. Also, at speed they're getting enough lift from the foils, so lift generated by the hull would not seem necessary.

Turn it upside down. AM’s hull shape is remarkably wing shaped, just upside down producing downforce instead of lift. That downforce increases righting moment, thus increasing power. 
 

That’s all just my theory. 

 

[Ex-yachtie]

We don't know whether the torpedo is for better hydro drag or to play with the mass within the rule.

If it's the later, and teams have done it to experiment with their wings, I really do wonder how much learning can be done using the torpedo foils.  If the intent is to give flexibility in the design of the wings, and one day you revert to an ETNZ style foil, can those lessons really be applied once the bulb is removed?

Of course, this assumes that the downside of all that flexibility is that the torpedo style foils are greater drag, which they appear to be.

 

[The_Alchemist]

If it's the later, and teams have done it to experiment with their wings, I really do wonder how much learning can be done using the torpedo foils.  If the intent is to give flexibility in the design of the wings, and one day you revert to an ETNZ style foil, can those lessons really be applied once the bulb is removed?

Of course, this assumes that the downside of all that flexibility is that the torpedo style foils are greater drag, which they appear to be.

Don't be so fast to say that the torpedo design has more drag.  The long wing foils of NZ have a very long leading edge and surface area that all creates drag.  The Torpedo is one large mass, but it is efficient in the amount of drag it creates (less surface area for a given mass).  There has to be more surface area in a pair of long wings than in a torpedo and two small wings.  Also, The long wings of the NZ foils may create too much lift and thus have to be adjusted (flaps, angle, etc...) to keep the boat stable as they sail.  The increased drag for the adjustments and longer foils can really slow the boat down.  If NZ doesn't have a VMG trick (like the last cup), they may get up quickly but be hunted down by AM.

 

[Rasputin22]

 

[barfy]

If you only have an actuator in the bulb, that's a long stretch of tube/rod to accurately control the torque at the far end of the flap. If there's an actuator at both ends, the torque issue is halved (in my simplistic view).

True that. Perhaps some deformation trailing off the flap angle towards the tip would be ok. There is mention of deformation in the rule, but would be hard to measure in the water I reckon.

Just can't see carrying all that drag for an external actuator when none of the boats so far, including mini moon, have had to go that route. They look look cool tho.

 

[The_Alchemist]

46 minutes ago, Rasputin22 said:

looks like the flat bottom didn't stick to the water like some are saying.

 

[Rasputin22]

looks like the flat bottom didn't stick to the water like some are saying.

Yeah, and everybody knows that water just abhors a round spoonlike object. 

https://external-preview.redd.it/AWUykynOy4RKhkoSq__TH4jI3Fp24NCIRBz5-nsvVjw.gif?format=mp4&s=ec21823f4adaf906bced15fb812145a68e912517

 

[wlrottge]

They sure look like airplane wing actuators in miniature. Are there any actual flaps visible? can you deform a whole foil surface by stressing it with such a device, so no separate flap? . Angles required aren't huge. At least we get to wildly speculate since they're visible. 

That was my thought as well.  Similar to what someone else said, a single actuator in the bulb would result in a lot of twist/deflection as you get further away.  The second actuator would allow better control of the foil twist.

 

[Stingray~]

If you only have an actuator in the bulb, that's a long stretch of tube/rod to accurately control the torque at the far end of the flap. If there's an actuator at both ends, the torque issue is halved (in my simplistic view).

Maybe the sharklets house actuators for flaps along those tip-ups?

 

[luminary]

Maybe the sharklets house actuators for flaps along those tip-ups?

Maybe its a weight balance to prevent/ensure correct twist of the foil? are they even allowed dynamic control of the foil? Thought it was just the arm.