Power Foils-added power to carry sail...

The Basic Concept:
One of the great advantages of a boat like the Hobie trifoiler, Rave or Dr. Sams new Osprey is that that dual wands operate independently allowing the boat to develop all its own RM without input from the crew. Hydroptere and every surface piercer I know of develop RM differently by increasing the separation between the center of lift of the main foils and the boat CG as it heels(leeward foil develops an increasing amount of lift). Hydroptere uses movable ballast as well.
I've been toying with the idea of a hybrid: a "bi-foiler" that uses retractable
small foils in each buoyancy pod-primarily in heavy air upwind. The point would be to increase the RM of the boat boosting upwind speed. The foil would be deployed in such a way as to hold the boat at a designed angle of veal heel along WITH crew participation. A target might be to add 50% to upwind RM and that would require a foil(actually one foil each side-only one used at a time) about half the size of a Moth mainfoil.
Disadvantages include the fact that two foils would be required and the additional weight. The gains could be appreciable, allowing a substantial increase in SA.
In light air the foils are retracted but the boat still has all the extra SA. So the gains would be not only upwind in heavy air but downwind in every condition and upwind and downwind in light air due to the extra power.
Takeoff would be significantly earlier than a "normal" bi-foiler....
Bradfield and Ketterman have already proved that the extra drag of a third foil is more than made up for in moderate to heavy air by the virtually unlimited rm available with their system. I think that it would be ideal to have these "power foils" able to be deployed without an altitude control system-a preset angle of incidence might work.
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Summary:
1) boat like the model with a vertical fin and small hydrofoil in each buoyancy pod;
2) only ONE foil used at a time,and probably ONLY with Veal Heel in winds of 12-15 knots or more
3) adjustable angle of incidence but NO Altitude Control System(wand)
4) allows more SA across the wind spectrum-up to approximately 35%.
a.In light air Power Foils aren't needed but extra SA is and will permit very light air takeoff.
b. In heavy air ,Power Foils add to RM from the vantage point of nearly the widest part of the boat. From a design standpoint this allows the Power Foil to be the smallest possible.
c. Extra SA and power to carry sail makes up for slight extra weight and minimal drag.
5) Power Foils easily and simply retracted.
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What do you think-I'd appreciate almost anybody's comments and/or insights
into the technical application of this idea. I'm going to test this thing on my new boat at some point-if I am still convinced of its potential then.

 

There will be a market for crazy boats like the one shown above. Complicated and difficult to sail? Yeah, but some people would call that fun.

 

Failure

This imaginary boat that has been "in build" now for years, yet still isn't designed, is now being trotted out under one more thread as another concept.

First it was going to be something that would be easy to sail and only foil downwind, or harder to sail and foil both upwind and down.

Then it was going to have some sliding ballast wing thing to help it foil.

Now it is going to have "Training Wheel Foils" TM to help it foil.

Next it will have a giant rabbit called Harvey as a mast and will foil on his giant feet.


In reality, different iterations of this monstrosity must be discussed ad infinitim on forum threads since the thing will never be built.

If you never build it no one will ever see it fail. That way you don't have to worry about the ridicule you will certainly receive when it fails just like the last contraption you built.

 

If we should tie him to something maybe it should be a POLE?

Funny, I didn't see any constructive advice in your replies.

No, he should build the thing in one mode, make it work, then think about the next iteration.

Frightened? No one is frightened of his crazy act. We all eagerly await the opportunity to comment on his finished project.

There is no doubt as to whether or not this never-ending load of nonsense is a waste of bandwidth.

Unless, of course, he can make the giant bunny version work. Then there would be something to discuss...

 

Power Foils

Richard, for some time there have been two or three individuals who would deliberately try to ruin any thread I started with baseless, ignorant personal attacks. This thread is about a DESIGN IDEA-not about my boat. It was started as an experiment to see if I could get some inteligent feedback on the concept. Instead-as I suspected-the same old same old trash.Thanks for your comments-an exception to the apparent rule. Too bad......

 

Doug, I deleted my message because I thought I might be making the problem worse, but I was too late.

 

It is an outright LIE that I was banned from this forum. I quit in disgust at the very kind of posts that are seen in this thread.

 

Pretty model is it R/C? and do you have any action shots or is it only a "mantle piece model"?

 

Maybe that is the solution this time as well.

Better yet, you have your own website, right? Why don't you add a forum and post all your nonsense over and over again, and see what great conversations you have. Thousands of people know about your site, so a simple announcement directing all the others who want to discuss your ideas to your site will suffice.

I, for one, will never go to your site to argue on your forum. Feel free to say whatever gibberish you want without fear of any comment from the likes of me.

You are no victim. People despise you for good reason.

 

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Thanks. No, its just a small conceptual model....

 

I have hardly ever spoken to Doug. When I first joined BoatDesign.net I was interested in adding foils to a Wharram cat, and Doug was direct and helpful in his reply.
I understand that some people are pissed off with Doug, but if you try to seek revenge in every new Doug Lord thread, you are being inconsiderate to the BoatDesign website. The moderator should be the one who decides when a member should stay away.
Time for a truce I think.

 

Power Foils

Just got thru doing some detailed calculations on the power foil concept. Here are the results:
1) boat--16' LOA ,12' beam, weight 160lb all up, crew 190 lb
2) power foil each side(only one used at a time):
a. 36 sq.in. area:2.25" chord; 16-18" span (depending on taper)
b. 7.1/ 1 aspect ratio(depending on taper may be higher)
c. 30% flap on first ones to allow experimentation(will not be required on finished version)
3) Max RM w/o power foil @ 20 degrees veal heel: 1475ft-lb
4) Max RM with power foil @ 20 degrees veal heel: 2225 ft-lb
5) SA w/o power foil= 134 sq.ft. W/SA= 2.61(equivalent to a Moth with 158lb crew)note: for reference Veal=154lb .
6) SA with power foil= 193 sq.ft. W/SA= 1.85(equivalent to a Moth with a 93lb crew-except the power foil provides the extra RM-in other words much more power for its weight than a Moth)
a. power foil contributes 34% of the RM at max.
b. small lever/dial will adjust angle of incidence for the range of -2.3 degrees to +.5 degrees corresponding to speeds from 10 knots to thirty knots/ 6 speed settings to optimize foil
c. no altitude control system(wand) appears necesary.
d. similar control to adjust flap experimentally-probably will not be required on finished version
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Tentative verdict: this damn thing may work-with a tremendous increase in SA(144%-- with a 150% increase in RM) for minimal additional drag in wind over 12-15 and no drag penalty under 12 knots wind.
These are really small foils and will be very,very light. The area of one foil corresponds to the area of both mainfoils together on the F3 rc foiler!




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Doug, what kind of mast would you use in the full-scale version?

 

I would hope to be able to use an unstayed carbon mast- if it can be light enough. Otherwise lightly stayed with non metal forestay and shrouds.

 

Doug:

This idea, like many of yours has the theoretical possibility of working under perfect conditions. The problem with sailing is that perfect conditions do not exist.

Wind is not steady, water is not flat, waves are not predictable and operator error happens all the time. Real sailing is more a game of dealing with the constant exceptions. Unpredicted gusts, random waves and chop, sudden heel changes all would make real world usage of your retractable upwind power foils problematic.

The other issue I see is that if you increase the sail area to take advantage of the potential for increased power, what happens when you are going downwind and the "Veal" heel power foils are not in play? Now you are overpowered and have not got adequate righting moment to deal with things.

If you are going upwind, using the power foil and things are working well, what happens if the combination of a sudden gust (increased leeward heel) and a wave trough causes the power foil to lose it's affect because it is now out of the water? Sudden loss of a bunch of necessary righting moment in combination with a gust on a now overpowered boat is a recipe for swim in these parts of the world.

This idea, like many of your others are theoretically great if used in perfect conditions in a model application where the intrusion of the real world has no consequences. A full sized sail boat with a live operator however bring the consequences of imperfect conditions into clear focus.

Perhaps your boat is designed for a far better real world sailor than I. I struggle to deal with all the randomness of real world wind, wave, chop and lulls constantly in a conventional skiff. Turning at the top mark and going through the twilight zone is always problematic. The acceleration from 8-10 knots upwind to close to 20 knots on windward mark rounding while doing a spinnaker set in even small chop is difficult on a conventional boat. It still scares me.

I can't imagine being on a foiler, losing a significant percentage of righting moment suddenly due to gust & wave ... at 25 knots? I hope your father is a medical doctor with good friends in the emergency room!

In perfectly flat water, with perfectly steady winds I can see this idea having the potential to be amazing. I seem to remember in your postmortem of the first aeroSKIFF you pointed to ICW chop and sea conditions as a major contributor to hull design problems.