High Performance MPX Foil/Self-righting Trimaran-The Test Model

Fire Arrow Foiler / MPX Foil System Testing and Development

A very interesting comparison of the number of foils and their loading between Gitana and Fire Arrow:

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Another thing that is interesting from a design standpoint is that Gitana''s foil system does not allow the main hull to fly all the time -and certainly not in a 5 mph breeze.
Fire Arrow-both the Test Model and the full size version are designed to fly the main hull(and the whole boat) in a 5 mph breeze. Theoretically there would be a trade off as a result, reducing top end speed. But that's not the case with the Fire Arrow System because the mainfoil is designed to create downforce in stronger wind, thereby making up for the emphasis on light air takeoff by creating more RM.
You can see that the main hull is not flying all the time in this great Gitana video taken in substantial wind:
https://www.youtube.com/watch?v=ce060M-XniQ

 

"But that's not the case with the Fire Arrow System because the mainfoil is designed to create downforce in stronger wind, thereby making up for the emphasis on light air takeoff by creating more RM."

Doug,

You really are sounding like a broken record. How many times has these words, or words to this effect been written by you.

Please please please - only write something if yuo have something new to say. Not the same old stuff over and over again. It is really getting boring. Over on SA we see exactly the same thing as we see here - almost exactly word for word.

 

And one other thing - why the hell do you insist on describing "uptip" foils as "UptiP"?

 

Fire Arrow Foiling System Testing and Development

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It may be the same words but it is a different context which serves to amplify the meaning of those words-since there still is a lack of understanding of how the system works.

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UptiP foils

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Because it may help to call attention to UptiP foils and their TNZ inventors. Still way too many people calling these incredible foils "L", "acute L", "L/V", "J". In my opinion,they should be called "uptip" or "UptiP" foils as described by Pete Melvin.

Link to Part 1 and Part 2: http://www.cupinfo.com/en/featuresindex.php

Quote from the article,Part 1, Pete Melvin:

When we were working on the rule, we knew you wanted to get as much lift as possible when you were going fast downwind,” Melvin says. "For instance, in the 2010 America’s Cup, sailed on giant multihulls, the maximum amount of lift we thought we could get was about 50% of the weight of the boat. At that time, we were still relying on the hull to provide pitch control, so what’s come out of this is the boats all now have elevators (the horizontal foils on the rudders).

“At Team New Zealand, we developed a new type of foil that allows you to keep your height above the water more or less steady. No one had been able to do that before, at least not on a course-racing boat that was not going downwind. We developed that mostly on our SL33 test boats -- they came with the stock constant curvature “C” foils and with those kinds of foils, you can generate 50% boat weight lift before they get unstable. But we noticed that when we could get one boat up fully foiling for a few seconds it would really accelerate away from the other boat – and that got the wheels turning. How, with such a huge potential benefit, can we achieve stable flight downwind? So our design team came up with the “up-tip” type of boards. We refined those on the 33s and our 72 is designed to do that and fortunately it worked right of the box.”[/QUOTE]

 

D4Z, an AC 4.8RC America's Cup Cat-2nd Sail

Too light over the 2 hours+ I was at the site-3.7mph max on Davis windmeter. Takes 5mph to foil at the earliest.... I got a little practice with the Trapeze Power Ballast System and found out that trying to video and sail this boat at the same time seems impossible with my current camera.

 

Fire Arrow Foiling System Testing and Development

"Lost" Fire Arrow video from 2014 in very ,very light air. Two weeks before the foiling video(s) :
https://www.youtube.com/watch?v=cOWTdv7WvsU

 

Fire Arrow Foiling System Testing and Development

This video was the 2nd day of testing(6/26/14)-not using a tripod-so the video is "hectic" but we learned a lot: 1) wands were too long, 2) ama foils didn't have enough area,3) rudder was too sensitive-needed expo and dual rate,4) rig was too loose, main was poorly set, jib sheet was messed up, 5) Two Stage ama design worked perfectly, 6) Don't try to gybe in overpowered conditions unless the boat is foiling! 7) Boat recovers well from a near pitchpole caused by #6.
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https://www.youtube.com/watch?v=jnQhXsDf6XY

 

D4Z, an AC 4.8RC America's Cup Cat

I decided to set the rig up with a shorter main along the original reefing lines.
This should make the boat a bit easier to handle and reduce the hassle of trying to keep the wind around 5 mph for tests. That is the maximum wind for the big rig w/o adding ballast since she'll double wind speed when on foils. This will allow a wider range of wind for initial foiling tests.

Reefed rig:

 

D4Z / Batfoil Testing

I'm giving serious consideration to removing the inboard iFlap on each Batfoil. The foils are angled out at the bottom 10 degrees and what I'm concerned about is that as the boat starts foiling the outboard iFlap will come out way before the inboard iFlap. This has been nagging me for some time but more so since I started testing. I'm thinking that the inboard iFlap is likely to cause a lot of drag in a range of speed, just after takeoff, where the boat should be able to accelerate.

 

Doug you haven't done any testing, before cutting things on a hunch, do proper tests and get a base line, then start changing one thing at a time, and do a lot more testing to confirm those results.

 

D4Z, an AC 4.8RC America's Cup Cat

Thanks, Wayne.

PS- while we haven't had enough wind to foil yet, the boat has a little more than two hours on the water "sailing" time in light air.

 

D4Z / Batfoil Testing and Development

Made the decision to go with the mods. Lots of study went into this and I'm satisfied that it is an important and timely mod.

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Wayne, no need to test when you just reinterpret the facts to fit the desired outcome.