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Apr 20, 2015, 08:30 AM
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DLord's Avatar

Ac 4.8rc


Jim, what area is the rig in the video? And weight? Congrads on your progress!
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Apr 20, 2015, 08:45 AM
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Quote:
Originally Posted by DLord
Jim, what area is the rig in the video? And weight? Congrads on your progress!
Area: ca. 1000 sq"
Weight: 1.23 lb
Includes 2 Servos to control the flap.

I'm quite pleased with this wing. The construction is different to my previous efforts, lighter and stronger. Might take a couple of iterations with the design to get satisfactory performance, but the basic structure seems to function well.
Apr 20, 2015, 09:40 AM
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Dick L.'s Avatar
Reducing size of wing makes sense. Better to have control AND speed than one or the other. Just as an FYI - in my last big cat class, soft sail rigs were running 30-32 feet tall (18 sq. meter sail area) and 11-12 foot beam. First well performing wing arrived (1982 - 1983) and was only 28 feet tall (don't remember sail area - but was much less) and owner had no problems dialing up the power.
Apr 20, 2015, 09:43 AM
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Looks like your on the right track!
Apr 20, 2015, 10:13 AM
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Dick L.'s Avatar
Reference to Post #18 (above) regarding solid wing 18 Square Meter ("Wild Turkey") - here is a photo I forgot I had. Most of my old sailing photos are still on slides, and yet to be scanned/converted.

Anyway - Craig Riley was owner and hulls were marine mahogany ply. Maybe you can pick up some details of interest.

Dick

Remember - this was back in 1982 -1983 ................. what took the sailing sport so long to "catch on"?
Last edited by Dick L.; Apr 20, 2015 at 10:15 AM. Reason: Added date reference
Apr 20, 2015, 10:25 AM
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Quote:
Originally Posted by Dick L.
Reference to Post #18 (above) regarding solid wing 18 Square Meter ("Wild Turkey") - here is a photo I forgot I had. Most of my old sailing photos are still on slides, and yet to be scanned/converted.

Anyway - Craig Riley was owner and hulls were marine mahogany ply. Maybe you can pick up some details of interest.

Dick

Remember - this was back in 1982 -1983 ................. what took the sailing sport so long to "catch on"?
Thanks for the photo Dick. It must have taken a great deal of effort and skill to build a boat like that without access to modern composites and techniques.


It is surprising that wing sails have taken so long to become mainstream. A similar point was raised on the German Mini40 forum last year:

http://www.jugend-forscht.de/projekt...autechnik.html

Using Google Translate: Peter Nowak asked himself , like a sail boat shall be constructed in order to achieve the highest possible speeds. For the optimum utilization of the wind of young researchers uses a rigid wing , similar to the wing of an airplane , rather than a conventional sail cloth . A low friction surface of the boat hull in the water , he achieved by the use of a trimaran , three hulls side by side. At low speed, the boat is moving on two hulls . However, increasing the wind speed and thus the intrinsic speed of the boat , the increased buoyancy of the four wings effected under water , that the entire hull lifts out of the water and the friction is greatly reduced.
Apr 20, 2015, 12:29 PM
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Dick L.'s Avatar
That sounds a bit like the experiments that Jean Margail (France) was doing shortly after building his r/c 2 meter multihull. His site: http://water.resist.free.fr/
Apr 21, 2015, 11:40 AM
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DLord's Avatar

Eagle 20 HF


For anyone interested in researching new, very innovative foiling systems read about this boat here: http://www.boatdesign.net/forums/mul...tml#post733763
No UptiP foils, no wand controlled foils, does not appear to be a surface piercing foil.
Comments by the editor of www.catsailingnews.com indicate that altitude is directly controlled by crew movement-no other foil adjustments.
I've written to the company asking for clarification.....
===========
UPDATE: will convert to the Whisper wand controlled foils-see boatdesign link above
Last edited by DLord; Apr 21, 2015 at 12:59 PM.
Apr 22, 2015, 03:26 PM
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DLord's Avatar

D4Z-- AC 4.8RC Foiling Cat


Back to work on the boat today doing a job I was not looking forward to. I bought an 8FG Futaba radio for the Fire Arrow tri so I could add functions if I wanted/needed to. Setting that boat up was easy for the two channels I used to start with but the worst thing about it was that damn "Touch Sensor" interface. My fingers did not get along with it at all. I had the hardest time with that thing last year.
The D4Z cat starts out with four channels-1) Rudder(s)(may attempt to use two channels each programmed differently to add Ackerman turning radius compensation), 2) Mainsheet(and jibsheet-may need a small servo and another channel of a backing line),3) Side to side ballast system, 4) Fore and aft ballast system.
At Tony Stillmans recommendation I bought a new 7ch receiver for the boat so I wouldn't have to take the FA apart. The new receiver was about 1/3rd the cost of the one that came with the radio. I was concerned about how to "link" the trans to the receiver. It was a piece of cake-no worries. I added a second model to the transmitter that was an "airplane" since it seemed that the all ready set up stuff was better suited. Had to change the frequency to "7ch" instead of "MULT" with the original receiver.
I shouldn't have been concerned-everything-including working with the "touch sensor" went very well. I double checked that the trans switched back and forth between the Fire Arrow set up and the D4Z-worked perfectly.
Tomorrow I'll get all the winches and servos set up and installed. Feel good now that I'm back at it....
Last edited by DLord; Apr 29, 2015 at 03:10 PM.
Apr 22, 2015, 09:12 PM
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Quote:
Originally Posted by rcmm
Some (very poor) footage of testing with a foam wing sail. The relative positions of the CLR and CoE are not quite right, and initially the sail was too tall. Will try a shorter wing and add a jib.

...
Please , that's PLEASE ; do NOT cut that wing down !!! ...
That's coming from a guy, that was # 4 in the world at ACRO on a rigid
wing hang glider !!!!

A tall rigid-wing needs attention ; rather than cut it down, try
lowering the AOA of the top 1/3 First. That will unload the healing
of the cat, and lower the center of lift on the wing.

If you cut that wing ; i promise, that i'll go Flying past you in a year
or or so. Learn how to deal with your energy FIRST !!

Bille
Apr 23, 2015, 06:35 AM
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Too late Billy. Actually, the chord of the main element is a bit too wide on this wing, I'll make a higher aspect ratio one down the track.

Images below of the foil configurations I intend to test when next on the water:
Apr 23, 2015, 08:35 AM
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DLord's Avatar

Ac 4.8rc


I like the left foil in pics 3&4* with a slightly bigger radius. Also, from what I've read
(and done) the vertical portion of the foil is better with some curve/angle so that the foil viewed from front or back tends to look like a "V". Looking great -can't wait for the results!
*corrected numbers(!)
Last edited by DLord; Apr 23, 2015 at 09:52 AM.
Apr 23, 2015, 08:43 AM
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None of the arrangements is ideal (conventional), as none of the foils were actually made for this boat. Hopefully I will learn something from them for the next set.

Note that the tip of the left foil in pics 3 and 4 rotates in response to a wand.
Last edited by rcmm; Apr 23, 2015 at 09:11 AM.
Apr 23, 2015, 09:34 AM
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Quote:
Originally Posted by rcmm
None of the arrangements is ideal (conventional), as none of the foils were actually made for this boat. Hopefully I will learn something from them for the next set.

Note that the tip of the left foil in pics 3 and 4 rotates in response to a wand.
May i have a close-up shot of the left foil , with the AOA at different
angles ? Sounds very interesting !!

You guys see GunBoat's foils ? Looks like a straight trailing edge, and
a nice elliptical front. Can't see the twist from this angle. Maybe catch
a glimpse here ; just before she goes turtle :

Wipe Out (1 min 59 sec)


Bille

Ps : i'm learning a Bunch , from you guys ---------- Thanks !!
Apr 23, 2015, 10:00 AM
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DLord's Avatar

Foils


Bille,in case you didn't know the UptiP foil used on Gunboat,GC32, Flying Phantom, NACRA 20FCS and other boats including by test model's ama foils was invented by TNZ for the last Cup. It is the only single foil with no moving parts capable of controlling the altitude of a catamaran foiler. The most recent versions require virtually no adjustment once flying.
This is a rather technical explanation of how they work and why the windward foil is always retracted:

The curved part of the vertical foil produces essentially the same lift as it rises. This is necessary to counter the side force from the sail rig, which does not change as the height changes.

Because the horizontal lift is constant but the vertical area is reduced as the boat rises, the leeway angle increases. It is the coupling of leeway with heave that is exploited by the L foil to provide vertical static stability.

The dihedral angle of the horizontal wing is set so that the angle of attack of the wing is reduced as the leeway angle increases. This satisfies the static stability condition that the vertical lift decrease as the heave increases.

Because the same horizontal lift is produced over a reduced vertical span, the sideways wash in the wake is also greater and the trailing vortices are more intense. This causes a coupling with the horizontal wing that increases the vertical lift, because the horizontal wing acts as a winglet for the vertical part of the foil (and vice versa). The dihedral angle required for vertical stability is greater than what one might expect by looking at the wing alone because it must overcome this wake-coupled influence. The result is there is a range of dihedral angles that provide positive vertical stability and a range of dihedral angles that are destabilizing in heave because of the coupling with the shed vorticity of the vertical part of the foil.

Although there are times when the foil tip has broached the surface, this is not the normal mechanism for providing heave stability in L foils. The best performance is obtained with the hull just above the wavetops and the wing submerged well below the surface. The leeway-modulated heave stability is still effective in this condition, and the induced drag is minimized.

Canting the foil inboard has the effect of increasing the dihedral angle of the wing, which enhances the heave stability. The vertical lift is spread over a greater span because the curved part of the foil is oriented to provide more vertical component of the force. This reduces the induced drag due to the vertical force. However, the induced drag of the horizontal force would be increased, so cant is typically used off the wind when the side force from the rig is less and the side force produced by the foils is correspondingly less. The foils still have to support the weight of the boat, so the vertical force is not lessened, but the relative proportions of vertical and horizontal force are changed, making the canted foil better suited to the operating condition. Cant allows the leeway-modulated heave stability to be increased an an acceptable penalty in the induced drag because of the lower side force and the higher speeds, which also reduce induced drag.

Upwind, the foils are canted to their vertical position to minimize the induced drag from the high side force and reduced speeds. The reduction in horizontal wing dihedral angle with vertical cant impacts the leeway-modulated heave stability, which is why it is much more difficult to achieve stable flight upwind than downwind. The crew had to be more active in trimming the wing and foil to deal with the reduction in natural heave stability, which was very hard on the grinders when flyng upwind.

Whether canted or upright, the mechanism for providing natural heave stability was still the coupling between heave and leeway, which led to a reduction in vertical lift because of the designed-in coupling between leeway and vertical lift by virtue of the wing dihedral. Reduction in horizontal/vertical-lifting area due to the foil tip broaching the surface was not part of this primary source of heave stability. Allowing the tip to broach the surface had big penalties in terms of induced drag and increased leeway due to insufficient vertical span.
__________________
Tom Speer
======================================
NOTE-1- Tom makes the point that allowing the inboard portion of the UptiP foil to penetrate the surface is slow but most newer boats do that all the time while foiling.
NOTE- 2- Source of the name "uptip" to describe these revolutionary foils was Pete Melvin here. Amazingly, many people still call these foils "J", or "L" instead of their proper-and unique name that mirrors their function.
http://www.cupinfo.com/en/featuresindex.php Foils that Shaped the Americas Cup, Part 1 & 2

“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.”
Last edited by DLord; Apr 29, 2015 at 03:10 PM.


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