Oh Lordy (Doug)

Monofoil

Jon, thanks for sharing so much information!

 

Great Reading Jon...although once again it will take me forever to get through it.

CT 249
It is still going on.
Lifting rudder foils starting to appear on Minis came from some of Paul Biekers work on Int 14s and could appear on larger stuff someday.(although a little too vulnerable for ocean stuff). How about the chines you are seeing on the Minis, the Volvo 70s and now the Open 60s...once again they saw much development in 14s. The US military were messing around with powered monofoil stuff (I don't know if they still are) I suspect they were paying some attention to what the Moth guys were doing. Sail and rig development are effected by what goes on in those classes. Those designers and builders, particularly in France and UK, are staying involved with these classes because they are where ideas sprout.

Enough of hijacking this thread. Back to the Monofoil.

 

Jon,
Thanks for the write-ups, good info, interesting reading. Of course I will offer my unsolicited opinion, which emerges from a dark, dank place somewhere in the vicinity of my posterior...

I was quite skeptical at first, it seems quite a complex machine. I like it though. It could be a speed breaker in somewhat mild conditions.

Still not convinced about a distance ocean passage at high speed. Dynamics of riding and slamming over big waves seems scary. Loads of a sizeable slug of water smacking into the structure at high speed seems like a tough issue too. I don't see any way around that, it's not a matter of if, but when, if you are in the ocean. I'm not saying you have not thought this through, but the ocean passage stuff, I'm not convinced.

Good luck. I'd like to see how full-size prototype does.

 

Jon,
I really appreciate your postings here, and probably all of us will learn a lot from you as you're the one doing the thing. But I recommend you to take things in an easier way. You'll learn that here (As I and others have done), if you want to publicly discuss your ideas. But, for sure, you are absolutely free to "get back to your cave"....

Cheers.

 

Aahh Guillermo He was just ticked off cause I was digging at him.
That was aimed at me but my skin is thick. I probably deserved some of it.
I know your intentions are good but I'd just as soon see that fire die out. Please?

By the way I was looking at the Google sat image of Pontvedra and I saw a yacht marina there. Do you know how deep that is? Looks like small boats. If you like, respond by personal message so as not to Hijak the thread
Thanks

 

Jonh Howes, I was impressed with your model and I am even more impressed with the path that you have crossed till you have managed that working model.

I am a sailor, but also an airplane pilot and clearly in that machine (I have difficulty in calling it a boat), aerodynamics plays a large part.
When I saw that model speeding, I have thought that it would be a lot of fun flying (not sailing) that thing (dangerous too). I guess that machine attracts more to the pilot in me than to the sailor…but perhaps it can represent the best of both worlds in the future, a Hydro-Glider, the perfect machine for the ones that like to sail and to fly .

I have foreseen some problems but you have already gone through them. Of course, you are going to go through a lot more when you do the real thing.

Best of luck, and please, keep us informed (when you can, post the 3rd paper, I am curious and very interested).

regards

 

Not really. All that development was done in the Antipodean lineage classes, the three skiff classes, NZ Javelins, and Cherubs principally. The i14s were way behind from about 1965 right up to the amalgamation and beyond. That's not to take anything away from current generation 14 designers and Paul Bieker especially who has done a tremendous job in taking the lessons from what were the more advanced classes, adding his own ideas and helping to bring the 14 back so that its pretty much state of the art now after decades when it was way off the plot.

 

Water Addict:

"Still not convinced about a distance ocean passage at high speed. Dynamics of riding and slamming over big waves seems scary. Loads of a sizeable slug of water smacking into the structure at high speed seems like a tough issue too. I don't see any way around that, it's not a matter of if, but when, if you are in the ocean. I'm not saying you have not thought this through, but the ocean passage stuff, I'm not convinced."

I entirely agree that this is to be proven. What we have at present is a small sprinter on the stocks, this is certainly good for the 500metre and one mile attempts. It is designed for peak to trough wave heights of four feet at full design speed, slowing down will allow bigger stuff to be handled.

A small model has sailed in surprisingly rough water (this was a big surprise to me as the waves where about three times the design wave), what it did was skip the foil from wave crest to wave crest, each time the foil re-entered the boat accelerated followed by coasting to the next wave crest, it did come a cropper a couple of times but recovered and went on until it piled up sufficiently for me to retrieve it. This was way beyond its design limits.

Our thinking is that the current boat would at least be good for an attempt on the Round the Island course record (Isle of Wight for non-Brits). This would at least tell us how she goes in more representative conditions. If we have the speed a lot of water can be covered in daylight so round Britain may also be a possibility if the boat can be shown to be reliable at lower speeds during darkness. In general, offshore sailing will be a steady development as has been the development of the boat itself. Big boy offshore stuff will need a bigger boat. Issues are that lying ahull in this thing would be nasty, it is very hard to reef a wing, it has to be streamed with zero or low incidence in which config it has lower drag than a mast but MUST be kept streaming to the wind or the forces run away fast. Against this, with the foil to weather and the wing streamed like this everything is very stable. Ideally however, it has to keep moving. Another possibility is that it should be fast enough to be able to pick its weather to a degree. It is not a certainty, it is something to be worked on.

Jon.

 

hi jon,

i really like your out of the box thinking and wish you all the best for your project.

the one thing that surprises me looking at your design [and it's only a gut feeling] is that the wing looks very small compared to the size of the complete vessel... including all the beams, crew pod, air rudders, foil and so on.
i'm sure you have done your calculations, but i guess we will see when it hits the water.
i don't think the size of the wing will be a problem at high speed due to the apparent wind, but for getting going and getting up to a speed where the apparent wind will really kick in, i don't know.

i'm really curious on one other aspect of your design. the foil.
i guess for the speed you are aiming at you will have to work with supercavitating or ventilated foils.
how do you plan to overcome the inefficiencies of these types of foils until the speeds where they work better than "normal" subcavitation foils?
i guess somewhere around the 40 to 50kn mark....


i'm into speed sailing myself on windsurfers and kitesurfers. i'm not a good enough rider to go for any records on my choices of craft as a rider myself [still stuck at 35kn over 500m and 39.7kn for peak speed], but i have been designing and building fins for windsurfers and a couple of kite speed boards that managed to get to 44.8kn over 500m and several peak speeds into the 46/47kn range.

i really like the simplicity and full scale development of wind- and kitesurfers.

on my windsurf fin designs i think i have the cavitation under control into the low 50kn range by using very thin foils [5-7%] and 30deg sweep.
kiteboards being essentially ventilated foils itself don't have that problem of course.

please keep us posted on the progress of your project.

regards
boogie

 

Hi Boogie,

The wing in the CAD drawing is optimised for speed as you surmised. The one we have built is a little bigger, 15 sq metres rather than 9sq metres as on the CAD model. We did this for exactly the reason you mentioned, ie, to get going as it widens our test wind speed range. Dependent on results a second smaller wing will be built but we may not need it as I could easily run out of bottle before this becomes critical!

The foil is a ventilated design and it is designed for a CL of 0.2. The section (ie 2D) L/D ratio is 22 which is low compared to a conventional wing section but it is consistent in behaviour. The high speed bit is just the tip, the bit above this has wider chord and is immersed at lower speeds when more foil is needed. A horizontal spur foil is used to fly the foil assembly partially out of the water until the spur planes on the surface with just the foil tip in the water below it.

Jon.

 

For the history minded; An ancient fore runner of this machine was described in a book of the late 1950s. The Book was titled; The 40 Knot Sailboat. The author was a US Navy commander assigned to the Bureau of Naval Ordinance. He made models of a type that seemed outrageous at the time. Smith, I think his name was. He reckoned that the reason a boat has limited speed is that the hull is in the way. That led to his foil program. That surely must make him one of the early foil afficianados. One of his model testing places was the reflection pool in Washington D.C. His models worked after a fashion. More than one of them had a winglike structure that indeed provided some lift when at speed.

 

Both Ketterman's Trifoiler and Cunningham's YP Endeavour were conceived and built as models, worked very well as models, then scaled quite successfully to full size. Both immediately increased their respective class records by huge margins (20-30%, not the measly 0.05% more typical of "modern" sailboards these days)

There are perfectly good reasons for modeling to be successful and perfectly good reasons why they often fail. It is not a coincidence that the same guys who understand things like scale effects are the same guys who go on to break records. "Experimenting at full size" is a perfectly acceptable form of R&D, if you can foot the bills. For others there is CFD. For yet others there are models. Hate the player, not the game, eh?

Interesting that you credit Drake with sailboard world records, when 1) he copped the original idea from another inventor and 2) there were some 1+ million "iterations" of the device--all built by others-not-Drake--before world records fell (and another million or more iterations before boards recaptured the outright record from YPE).

Dave

 

Sorry I didn't discover this thread 2 weeks ago. Some random comments:

Be a shame if the design only beat the various flat water outright records. That'd destroy my confidence in the man altogether, don't you agree?

I must have missed this part; only heard him say he'd been "taken" by "earlier charletans" or similar. Is it true, DG, that you have speedsailing experience? Which boat(s) and what years? Not trying to pin you down, DG, but as you said yourself, nobody here should deign to pass judgment on speedsailing designs without personal experience--lots of it, I believe was your gist. Will you provide us your own specifics, please?

DG's already been jumped on for this comment, but I believe I have a new slant on it--what makes you think that outright speed record teams have spent, or have access to, large engineering resources? The Cunningham crowd are famous for their "bare bones" approach; Ketterman built his boats out of his own pocket (as did Coleman with Crossbow--though slightly deeper pockets). The very concept of "sponsored speed attempt" is widely regarded as an oxymoron within the genre--unless you happen to be riding a big board manufacturer's product, and then it's more a style play than engineering.

Though I'd dearly love to meet the man and I wish to take nothing away from his monohull accomplishments, there are numerous errors in Bethwaite's book (cf pumping, which he completely misunderstands). From the presentation and (lack of) engineering presented regarding his whole multihull project therein, it's pretty clear the project was more to "prove" the "superiority" of skiffs than to do any real testing of multihull concepts.

Cheers,

Dave

 

I see of course you meant this tongue in cheek, but yes if the flat water records were broken it would be a significant acheivement. There was the claim that the rig could beat ocean passage records as well, and of this I am a bit skeptical. I think rough conditions might be a bit much for it. But I respect the idea, and not saying it can't be done.

 

I don't credit Drake with speed records. I said he created the style of craft that holds the record.

I can't see the relevance of the fact that Jim went back to his succesful career in science and didn't design the boards that broke the record.

You say he "copped the original idea from another inventor". He denies this; "I had no knowledge of these two earlier efforts at the time" he said to "Wind Surfer" magazine3 and to others. I get the feeling he may know.

If you're referring to Newman Darby's ideas, standing on the lee side and leaning against a square sail seems very different to standing on the windward side of a "normal" sail hanging onto a wishbone. The fact that the Windsurfer patent fell in the UK has been used as an example of poor patent drafting which obscured the fact that the Drake/Schweitzer board was, in fact, a considerable inventive step. If Drake had known about the Chilvers and Darby boards he would probably have been able to draft a patent that would remain valid even when that prior art was brought up. Your case demands that he knew about the earlier boards; that he is publically lying on record about that fact; and that despite knowing about the prior art, he made no attempt to ensure that the patent was drafted to remain valid despite it. Big call.

I agree that model tests can be very useful. Of course, scale effects can be accounted for. However, the fact that there are such significant matters as scale effects to work through, is the reason that some people don't want to just assume that the real thing will work from a model. Surely Smith, a physicist, knew of scale effects? But why didn't his full scale efforts work?

Sure Cunningham worked from models. The Cunninghams had done so for years; their C Class cats were tested in irrigation ditches. Charlie used to carve boats from sticks and play with them in the water tank when he was a little kid. However, the Cunninghams had also lead the way in dinghy design in the '40s; lead the way in cat design in the '50s and '60s; won the Little America's Cup; etc.

Winning so many races proves that the Cunningham team really know their full-size real-world stuff. But when we are presented with teams who don't have decades of experience in winning world-class races, why should we assume that they can take a concept from model to full size just as well as the Cunningham team can?

The Cunningham team has also got it wrong, like with their canoe sterns (derived, I think, from their model tests). Once again, it seems like more proof that just because someone shows us a working model, we shouldn't merely assume that the concept will work full size. That's about all some of us are saying.