New Trimaran Foilers

Maserati foil control

Good info-thanks. Using the rudder foil to control altitude would be the least effective way to do it on a trimaran with the Fire Arrow configuration(main foil+ ama uptip foil+ rudder t-foil)especially when they say (above) that the daggerboard lifting foil is the largest lifting foil on the boat. Seems to me they must have active control of the daggerboard lifting foil-- maybe manual?

 

By load the ama uptip foils must be the largest. -Unless they take on water ballast.

By my reasoning the dagger T should only need to be trimmed for significant changes in wind speed or direction and it would literally tilt the boat. On the small plane I flew the wing flaps were 'trimmed' (rarely) for speed with a little wheel and the tail flaps 'elevator' were what you control with the stick. Why do you say the rudder is the least effective way to control height? You understand that the most effective control is the one that requires the least energy input. If the altitude is controlled by the dagger T (like the moth) there is no reason for the rudder to have flaps.

These 70s are mostly sailed short handed aren't they? 1 or 2 crew. So I wonder what the rules are for autopilot. It would be easy to do a slick electronic flight control autopilot but that does not seem fair.

 

Foils-Fire Arrow Configuration/Maserati

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I learned that from Dr Bradfield when we discussed why the flaps on the Rave were on the two main foils. Normally there was no rudder foil AOI control at all. Dr. Sam said that if you had a fixed AOI on his main foils the boat would be subject to wild pitch excursions just before it capsized due to lack of RM.
The AC 72's were forbidden from adjusting the rudder foil while racing so all they had was rake adjust of the single main foil.
The logic , I guess is that the rudder foils are 'trailing " foils and follow the main foil w/o adjustment. Has to do with the position of the CG and the height of the CE above the main foils. The CG, on Bradfield boats, was positioned so that 80% of the load was on the main foils(which were attached to the daggerboards). The load on the rudder foil was 20% and the pounds per sq.ft. loading was much less on the rudder foil.
The Fire Arrow, Rave and many other foilers would have serious control problems if the only altitude control they had was the rudder foil. Thats why I'm sure(and they say as much) Maserati has some sort of AOI control on the main foil.
As to the size of the mainfoil/ama foil on a Fire Arrow configuration trimaran: the area of the mainfoil is greater than the ama uptip foil area because it has to lift 80% of the weight at much lower speeds than does the ama foil which can wind up lifting 100% + depending on the level of downforce on the main foil and rudder foil* but at much higher speeds.
*a trailing symmetrical rudder foil can automatically go from vertical lift to downforce as a result of the pitch of the boat.
The wand or manually controlled mainfoil is set to +2.5 degrees AOI and the rudder foil is set to zero degrees both relative to something like the static waterline.
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David Luggs I14, that foiled in 1999, used a large rudder foil with a very small daggerboard foil(canard confiuration) and he was able to fly it manually controlling a flap on the rudder foil.
But most foilers are "airplane configuration" with a small trailing rudder foil or foils and a larger main foil or two with the majority of the loading on the main foils.

 

I see your point about load at takeoff, but the proportion on your model is the result of extreme beam. Maserati has a much smaller beam relative to mast height and I suspect their takeoff speed sq. is closer to max speed sq. than your model. This brings us back to my view that your problems are of you own creation due to excessive beam on MPX model -we don't need to rehash.

Just to finish about Maserati -you haven't seen anything reporting how they control foils? electronics? Hydraulics? Sensing? And you haven't seen anything in the rules limiting foil control?

And for clarity, when I (or most people) talk about control I refer to something monitored and varied continuously in normal operation. There are still other settings that are trimmed or altered -which is what I would expect for the forward foils of Maserati.

 

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The oversquare beam of the Fire Arrow is less than the multiple of length of Hydroptere's beam.The Fire Arrow beam is no where near "excessive"-- it allows one of the most powerful trimaran platform's for its length. But it would be excessive without the daggerboard foil+ rudder T-foil working in concert to facilitate light air takeoff and enhanced pitch control compared to any trimaran not using the Fire Arrow Foil System.
For the record, Maserati's RM is 27 times its displacement*, whereas the Fire Arrow RM is 3.28 times displacement. So their main foil has to be large-in fact they say it is the largest foil on the boat.
* based on their published figure which they say is "light displacement".
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I've written to Team Maserati and am keeping my eyes open for any stories on their system. The quote below from post 11 of this forum seems to show that they adjust the incidence of the main foil:

 

Nothing above changes my mind. "excessive" is an opinion. Maybe a nicer equivalent is 'your design would be cheaper easier and better behaved if it was narrower'. If I want to discuss it further I will post calculations on your FA MPX thread.

Thanks for the Maserati info but it doesn't solve our argument -I still think they just use it to trim the boat to conditions. Odd wording -I presume it was a translation. I hope you will share here if Maserati gets back to you.

 

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Amazing!

 

Fire Arrow Foil System / Maserati

Checked the Maserati/Soldini site tonight and the links to the various categories appear to be dead.
UPDATE: back up today.......


http://maserati.soldini.it/

 

Maserati with Fire Arrow Configuration

Maserati using the basic Fire Arrow System 7/18/16:

 

Maserati

Crash!
Fire Arrow Foil System temporarily gone due to a serious collision with an underwater object which literally tore off the stb rudder and foil, rudder post and bearings! Since it was the stb side(where they have an uptip foil) they may have had to remove the main foil as well because without the rudder foil the main foil and uptip foil won't work. Too bad for the Team! http://maserati.soldini.it/maserati-multi70-in-malta-with-severely-damaged-rudder/

They don't specifically say they removed the main foil. They may be able to leave it in with very little to no lift on it. The stb uptip foil has to come out. And they were already sailing w/o the port uptip foil. Imagine -one collision and 10 years+ back in time!

UPDATE: The Maserati website is back up again again as of today,10/20/16.

 

I gather from the photos posted on FB of the repairs to Maserati they are going to run with a C foil for the Middle Sea Race, some nice detail shots of the individual components, rudder and steering bearings etc here as well:

https://www.facebook.com/giovannisoldini/posts/10150671789624943

 

Maserati without the Fire Arrow Foil System

Thanks, Corley-their site has been down all day. I read there last night that they removed the stb ama foil and I guess they're using the same "C" foil they have in the port ama. I'll be amazed if they get the stb rudder fixed but I guess since they're not foiling they could do without it? I just saw what they did with the stb rudder-what a job!
I was sure looking forward to them being able to fly during this race and I know they were too-damn shame.

 

The link above is dead, but some info can be found here: http://www.sail-world.com/Australia...a-with-damaged-rudder/149042?source=google.it

 

Not too hard to see why it failed, the back half of the rudder bearing was totally unsupported!

 

It seems to be an intentional design feature for controlled failure, at least by looking this photo: https://pictures.dealer.com/m/maseratiofsanfransisco/1011/e2a9a428fe760d1f67326dff0d160173x.jpg . The structure around the rudder bearing is thin and elastic, resembles a terry-clip. It was made to let go at impact, IMO.

After all, the hull structure has remained undamaged, only the C-shaped rudder stock bearing seem to have failed during the impact. Hence the repairs will not take too much time and the repair costs have quite surely been contained in this way. I say it was a smart idea.