New High Performance Monofoilers

[Chris Ostlind]

Now, AK... tell us how Doug's disconnect affects the parameters, as defined by Rick in his post above. No wind on the lake, and the pedal driven craft kick the crap out of the Moth foilers, as well as any other wind driven boats, every time. Is that also slanging, when all he is doing is stating the realities?

Again, AK, you can look at the definitive function of what is being claimed and source the purpose of the so-called argument. To not be pragmatic in these things make you seem like you are egregiously slanted in your interpretive skills. From what science background do you derive this perspective?

If you want to call that slanging, then I wear the term with a very high degree of confidence.

[markdrela]

Originally Posted by Rick Willoughby

As far as speed goes the fastest pedal boat has achieved 18.5kts and that was a long time ago with a person of above average athletic ability but not an elite athlete.

Hey! I resemble that remark.

I wonder how fast a pedal boat could go with the latest technology and an elite athlete. Or even a person of average ability.

After the Decavitator a few of the remaining people tried to build a "sport" hydrofoil HPB with a more practical water prop. I posted a sketch here, but without the hydrofoils:
Pedal Powered Boats
The hydrofoil system was essentially the same as on the Decavitator, except there was no small high-speed wing, only the larger intermediate-speed wing. I was able to cruise below my AT at 11-12 knots, so in that sense it worked. We never got beyond the initial testing because most of the people graduated and left.

One thing that became clear:
Even if the power is low enough to sustain flight for an hour, say, a hydrofoil HPB is still very mentally exhausting. The reason is that you cannot let up, else you drop down unto the hull, and have to anaerobically power over the hump to get going again. In that sense it's like climbing a 30% grade on your bike while maxed out in your lowest granny gear --- let up for a second and you stop and fall over. Hence, the target minimum power for flight should be well below the expected available cruise power.
The Decavitator's "big" wing that we used for this new boat was a bit too small:
118 in^2 area
59 in span
2.0 in average chord
This was fast, but the power was just too high for mentally-comfortable crusing (see point above). The next time around I would maybe scale up the wing by 1.2x or so.

[Rick Willoughby]

Mark
What power level did it take to achieve the 11 to 12 kts? (Sorry if I did not accurately categorise your athletic ability.)

For my long distance cruising I design for 6.5 to 7kts with a displacement hull. This can be achieved with 130 to 170W. My long term output right now is about 130W but I could get better with more dedicated training.

I figure a foil to achieve flight around the 7kt mark would require something like 170W which is beyond my continuous output so I have not bothered doing it seriously. I made a foil for one of my older boats but could only get it to lift clear; hull still partially immersed. The hull was heavier than needed for a purpose built foiler.

What would be nice is a two-mode system where you can throw a lever and set foils into place that enables sprint speed for maybe 1000m. I can hold about 250W for five minutes or so. In displacement mode this gives me just under 8kts. It would be great if I could get more like 12kts with that power level.

My unsupported prop arrangement is very low drag and I could get high 80s efficiency at that speed.

I can already give rowing sculls a fright and I have a long-term ambition of asking a rowing 8 to move over so I can overtake. I think that would be something to behold. A grey haired old fool blasting off a rowing eight.

It is a pity you are no longer doing research in the HPB arena. Decavitator has inspired a lot of thinking on boats - it is often referenced. I can already see an increase in interest in efficient human powered craft and not everyone has the persistence or physique to learn to row or paddle efficiently.

I have sailed quite extensively mostly in keel boats but I get the greatest thrill from just cranking up the pedal boat. It has to be the best fun you can have on water.

Rick W

[markdrela]

Originally Posted by Rick Willoughby

What power level did it take to achieve the 11 to 12 kts?

My guess is somewhere around 220 Watts. This is for my 140 lb body weight.

I should stress that specifying required-power without specifying the rider weight is almost meaningless. For our 50 lb boat, increasing the rider weight from 140 lb to 154 lb (a 10% increase), theoretically increased the cruise power by 11.1% -- almost in proportion. So the required-power nearly matches the available-power for different-sized people of comparable athletic ability.

What would be nice is a two-mode system where you can throw a lever and akset foils into place that enables sprint speed for maybe 1000m. I can hold about 250W for five minutes or so. In displacement mode this gives me just under 8kts. It would be great if I could get more like 12kts with that power level.

That's theoretically doable, but a real mechanical challenge for a number of reasons. To minimize both 2D-wave drag and 3D induced drag, you want a very long skinny wing --- see the wing specs in the previous message. This was just barely doable with the molded solid-carbon wing, with two struts 26" apart. A single strut would be out of the question. But the real problem is retracting such a long wing -- it can't go up through the hull. Retracting the two front inverted-T surfaces and skimmers would be relatively easy.

I can already give rowing sculls a fright and I have a long-term ambition of asking a rowing 8 to move over so I can overtake. I think that would be something to behold. A grey haired old fool blasting off a rowing eight.

With the Decavitator, I actually did a few times run past the heavyweight 8's on the Charles river like they were standing still.
We never measured the max speed of the water-prop boat, but I estimated it had to be something like 15 kts in a hard sprint. Faster than an 8 by a few kts, but one can't keep that power long enough to pass the entire boat length.

[Rick Willoughby]

Mark
Your 220W figure gives some promise.

I have been reducing target weight for boats since I started playing with pedal boat about 6 years ago. The 4th one was what I thought would be a good weight. It came in at 38kg. I thought 7th would be just about the best you could get using a professionally built OC1 with a bit of strengthening. The hull and outrigger are 16kg but by the time the drive was added it came in at 28kg.

My latest boat (4th variation of 11th design) is just over 20kg and my new target is 15kg. I might be able to set up CF foils and support for about 2kg so total around 17kg. I currently weigh 156lbs but I could get down to maybe 140lb if I was to train in a structured way and not overeat. A picture of the latest boat is on the Pedal Power Boat thread:
http://www.boatdesign.net/forums/att...s-pc240005.jpg

I will look more closely at the possibilities when I have finished my new CF hull. Aluminium was my preferred material but I do most things now in CF now. I have a nice TIG welder that I hardly use now.

I am thinking of three separate "T" foils. One off each outrigger and a third smaller one at the bow of the boat.

Rick W

[markdrela]

Originally Posted by Rick Willoughby

I am thinking of three separate "T" foils. One off each outrigger and a third smaller one at the bow of the boat.

The two lifting T foils will work well, provided you can join them at the center after deployment -- a gap would be really bad for induced drag. By appropriately setting the spanwise separation of the vertical struts you can make the bending moment at the wing center to be nearly zero to simplify the joiner problem. You can have a tube in one wing and a pointed-end rod in the other wing, so the two ends just automatically plug together.
The three other problems are
1) roll stability
2) depth stability
3) depth control.
On the Decavitator we got 1) and 2) at the same time with two independent front T foils each with a surface-skimming sensor.
With a single surface-sensing T foil you'd get 2), but still need to address 1). The single main wing does have a little bit of roll stability from the free-surface unloading effect, but it isn't much.
We got 3) by making the incidence of the wing adjustable. The entire wing/foil system moved as a unit, avoiding any underwater hinges.

[ancient kayaker]

The retractable foils are of interest to me - do you have a link with details of how it is done? I tried google but I kept landing up in a moth vs RS600FF war zone.

[Rick Willoughby]

Originally Posted by ancient kayaker

The retractable foils are of interest to me - do you have a link with details of how it is done? I tried google but I kept landing up in a moth vs RS600FF war zone.

I realise there would be more induced drag with twin "T" foils but that was the only way I had thought about using them. They would be mounted off an outrigger cross beam located near the CoG. They would have a longitudinal shaft that allows them to be rotated clear of the water. When used they would be rotated into the water. Mark has suggested that they be wide enough to have a tapered pin and matching recess so the two "T" foils form one wide continuous foil when fully deployed.

You would slow to deploy the foils so they are unloaded but, because they roll down in their transverse plane of operation, they would not present much drag when being deployed. Once locked in you would power up. I would probably have spring lifting and pull cord for locking down.

It might make sense to mount the outrigger cross beam in bearings so the angle of the foil can be tweaked.

The first foil I tested was intended to lift around 8kts. It was 8ft wide. I thought it would provide roll stability but I sit on the hull and once it started to lift the outriggers I would always get into a roll attitude and could not correct. I was thinking that two wide set "T" foils would provide inherent roll stability. I realise there would be some loss of efficiency.

Rick W

[sailor2]

A word monohull describes a boat with one hull. Shouldn't word monofoil describe a boat with only one foil ?
It seems 100% of the boats mentioned in this thread that fully foil have more than one foils. So why are they still refered as monofoilers ?
Isn't a boat like a moth a bifoiler instead ? Is this just sloppy language or is there some logic behind the usage ?

Monohull foiler=monofoiler. A monofoiler can have just two foils like a Moth and other bi-foilers or three or more foils like the surface piercing Moth sailed by Brett Burvil or the numerous "ladder" foils of the first monofoiler in history-the Monitor.

[sailor2]

Originally Posted by Doug Lord

Monohull foiler=monofoiler. A monofoiler can have just two foils like a Moth and other bi-foilers or three or more foils like the surface piercing Moth sailed by Brett Burvil or the numerous "ladder" foils of the first monofoiler in history-the Monitor.

I see, so people classify foilers by the amount of hulls in the air having no effect on sailing capabilities in normal operating conditions. That's due to tradition then rather than logic. Bi-foil & trifoil & quattro-foil describre amount of foils but mono-foil discribe number of hulls instead. Wierd logic.
Is a 3 hulled vessel with 2 foils called a trifoil bi-foiler or just multifoil bi-foiler ?

What if someone one day in the future happens to find out how to make a windsurfer foil with just one foil in the water. In theory having electronic automatic control systems on the only foil and sailor using windsurf type sail to keep pitching moments withing limits by shifting bodyweight that should be possible in theory. What would that be called then ?
A foiling windsurfer I guess, but ...
Or is it already there ?

[Chris Ostlind]

Actually, Sailor2, there's another reason for all this wordsmithing and if Doug is honest about it, he'll muster the gumption to tell you. Right Doug?

You are right, S2, the language already has plenty of descriptive terms for all this wanky foiler-smithing and new words were not necessary at all. It falls under the same pattern as using words like AeroSKIFF for boats that can't foil. The euphemism, AeroSKIFF, is marvelous, sending the message to the reader that somehow, the "Aero" desginator actually indicates a boat that has some kind of aeronautical component. Unfortunately, no AeroSKIFF has ever flown, or Doug would have video proof of same, just like he indicates about his foiling model boats.

From the thread regarding the pie in the sky "60' monofoiler" that Doug dredges-up every once in awhile for pure entertainment value...

Originally Posted by Doug Lord

... Video was taken and was part of the original presentation on the website but was removed when the site was downsized. No still pix. No boat was tested to destruction. My windmeter only measured in mph...
Still some video on the microsail site...

Isn't it interesting that the model boats, at a speck of the cash outlay, have video confirmation... yet the magnificent, thoroughly conceived and full sized, AeroSKIFF, does not? One would almost think that the guy is pulling our leg(s)

So, Doug... where is the equivalent video clip of the vaunted AeroSKIFF doing it's bad thing in your local waters?

[bistros]

Originally Posted by sailor2

I see, so people classify foilers by the amount of hulls in the air having no effect on sailing capabilities in normal operating conditions. That's due to tradition then rather than logic. Bi-foil & trifoil & quattro-foil describre amount of foils but mono-foil discribe number of hulls instead. Wierd logic.
Is a 3 hulled vessel with 2 foils called a trifoil bi-foiler or just multifoil bi-foiler ?

What if someone one day in the future happens to find out how to make a windsurfer foil with just one foil in the water. In theory having electronic automatic control systems on the only foil and sailor using windsurf type sail to keep pitching moments withing limits by shifting bodyweight that should be possible in theory. What would that be called then ?
A foiling windsurfer I guess, but ...
Or is it already there ?

It's been done, as has this discussion ad nauseum. There is no point in arguing terminology with Mr. Lord, he's already decided what you should think.

Just as a heads-up, you are starting down a long, ugly road .... as one who has already traveled it, I would recommend you think very hard about proceeding. There is absolutely no benefit in trying to debate Mr. Lord regarding foiling technology, the science behind it, the real market potential or anything else. If you are looking for suitable linguistics that apply, you could try monomaniacal and bipolar, although I'm not referring to the boats here.

Move along, these aren't the droids you are looking for .....

[ancient kayaker]

Originally Posted by Doug Lord

Monohull foiler=monofoiler. A monofoiler can have just two foils like a Moth and other bi-foilers or three or more foils like the surface piercing Moth sailed by Brett Burvil or the numerous "ladder" foils of the first monofoiler in history-the Monitor.

I got to admit I was as confused as S2 was. I guess if the real monofoiler ever shows up we will just have to call it the unifoiler. Of course it might turn out to have a perfectly good French name!

Etymologically speaking, the prefix uni- is Latin, as is bi-, so it's more consistent than mono- which is Greek. Practically speaking, nobody gives a damn.

Comment from SA by Sean M regarding the R Class:

"Definitely suited to narrow boat in our experience, but hydro foils have laid waste to conventional foils now as the speed gain is massive whilst not losing any height, but gaining that as well! Next season most of the R fleet will be on foils, so I guess that we will be adding to the classes on foils as our rules are open to developments. "


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An example of the future of Skiff design:
www.rclass.org