Windmill or Wind Turbine- powered boats: how many are out there, and are they viable?

[Guest625101138]

Originally Posted by MPraamsma

Rick,

I also did a million plots with JavaFoil and others, and I started to get the suspicion that the programs were just looking at standard tables to predict drag based on the flow velocity over the surface. Obviously the venturi goes supersonic pretty soon compared with the external foil, and by their reasoning is producing a lot of drag. I tried to throw a curve ball at the program by putting two objects in the flow field adjacent to each other, and the results were very questionable. In the diagrams attached, I put an automobile shaped body next to a venturi body, and it clearly shows the extent of the disturbed air ahead and behind the car, and the undisturbed air near the venturi. All the dark areas represent lost energy. Yet calculated separately they showed similar Cd. I'm not sure these programs take the reflected wave into proper consideration, otherwise, where is the lost energy evident in the venturi plot.

You might also try feathering the inlet and outlet more to avoid the abrupt changes in direction, and also make the external surfaces totally flat and parallel. You may notice that the slightest pertubation on the outer surface produces far field effects.

Michael
Javafoil is an analytical method. The results for pressure and velocity are derived from basic physics up to the point of foil stall and then they have selective method of determining that condition. Stall is not an issue for the foils in the in-line condition.

For simple foils the output compares closely with wind tunnel test data.

When you have multiple elements there can certainly be inconsistencies in the results. I look at the drag for total and each element to see if it makes sense. In the case of the back to back cambered foil if they are touching the result is inconsistent. In the set up in the earlier post, with small foil separation, the drag is the same as a symmetrical 20% foil.

In the case of the venturi the internal velocities are very high and this could certainly introduce errors in the frictional drag. It could very well overestimate the drag because the internal velocity is 2 to 3 times more than the farfield. It begs the question, what Re# is applicable on the inside.

There is certainly no allowance for adiabatic cooling within the venturi if this is actually occurring.

So Javafoil works well for what it was primarily intended to achieve. I have made numerous propellers that perform very close to prediction based on foil data generated from it. The reason I use it it is that it has a wide array of foils available so I can select the best foil for the application rather than being limited to the few that I actually have test data for.

In using it for more complex arrangement of elements it needs some care and assessment of results to ensure they are consistent.

Rick

[Guest625101138]

Originally Posted by backyardbil

Rick
How can you get over this problem? I think the natural wind is pretty variable all the time. Could you adjust the pitch ratio easily? or would changing the mechanical gear ratio do the trick.
P.S. did you do any more testing yet?

bil
For now I will use the low pitch prop so I have a wider operating range. The bottom limit of performance with this prop is primarily the seal drag in the gearboxes. Neither box has done much work so the seals are tighter than when run in. Irrespective it will operate in quite low wind.

Ideally you would have continuously variable gearing so the turbine can be spun up unloaded and then gradually loaded to speed the boat up. The gear ratio would be inched higher to the point of maximum power from the turbine. It would be constantly trimmed to get the best speed. This is virtually identical to what is done in any sailing boat. The sails are constantly trimmed or the helm adjusted slightly to keep the boat at best speed.

I was so impressed with the windward drive in the initial test that I thought I could carry the larger pitch prop. It did work but the operating range was in much higher wind.

The turbine pitch is closer to 900mm than 1m and the 625mm pitch prop is optimised for an easily driven hull. When it is required to push the turbine as well there is insufficient blade area to get the best efficiency. To go directly into the wind with this combination I need a combined efficiency of turbine, prop and gearing in excess of 60%. This is a big ask and only achievable in the stronger wind.

With the lower pitch prop the required combined efficiency is less than 40% to go to windward and this is achieved most of the time. The boat makes apparent wind as soon as it starts to move.

I have put this boat together with bits laying around. It takes time and effort to build a coherent design and the turbi-prop concept does not offer any great performance potential beyond the ability to sail directly into the wind.

For a practical design of a purely mechanical system I would recommend use of an efficient CVT. This will give the widest possible operating range.

The real advantage comes with electrical transmission combined with battery storage. This decouples energy collection from energy delivery. The energy collection can fluctuate all over the place while the delivery is at an efficient average level. The parts to do this at the single person scale are cheaper than the mechanical gearboxes.

I am all set for another test this weekend and have the photographer lined up. With some friendly wind I will get better data and video. If I can crack 10kph on any point of sailing combined with making authoritative progress directly to windward I will call it quits until someone can provide a GPS trace and video clip that betters what I can demonstrate. It has to be manned of course. Next step would be a CVT and optimised prop but I have too many other things to play with that make more sense.

Rick W

[Windmaster]

Originally Posted by Rick Willoughby

bil

I am all set for another test this weekend and have the photographer lined up. With some friendly wind I will get better data and video. If I can crack 10kph on any point of sailing combined with making authoritative progress directly to windward I will call it quits until someone can provide a GPS trace and video clip that betters what I can demonstrate. It has to be manned of course. Next step would be a CVT and optimised prop but I have too many other things to play with that make more sense.

Rick W

If the wind was for example 20mph then 10kph (6.2 mph) downwind will certainly be no problem with pencil shaped hulls. In fact you would not need to even couple up the propeller, it would work just as well in "autogiro" mode.
With this kind of fast-rotation turbine it might even be effective reaching (with the wind from the side) even with the prop decoupled (if you adjust the angle carefully). This was shown in the 1930's by Moore Brabazon with his Solent Redwing class boat. However, going directly to windward it is likely to be unpleasant and what is meant by "authoratative" progress? It needs to be related in some way to the speed of the wind prevailing at the time.

[Windmaster]

Originally Posted by Rick Willoughby

bil


The real advantage comes with electrical transmission combined with battery storage. This decouples energy collection from energy delivery. The energy collection can fluctuate all over the place while the delivery is at an efficient average level. The parts to do this at the single person scale are cheaper than the mechanical gearboxes.

Rick W

Yes, but if you store up energy to use later that's not much of a challenge is it, because you can use any kind of setup and it does not have to be efficient. On the other hand gathering your energy and using it at the same time against the wind is the truest test of your components and their efficiency.

Anyway, all this talk of efficiency makes it look as if going directly against the wind powered by the wind is a borderline activity which might "just work" if you get everything right and you make this or that subtle adjustment of pitch, gearing and get the "correct speed of wind".

I don't find this to be the case. Using the way I have developed, it is simply no problem going directly against the wind and there is so much force available that these subtle nuances of adjustment seem trivial. I have given enough clues already of the best way to do it!

[Guest625101138]

Originally Posted by Windmaster

If the wind was for example 20mph then 10kph (6.2 mph) downwind will certainly be no problem with pencil shaped hulls. In fact you would not need to even couple up the propeller, it would work just as well in "autogiro" mode.
With this kind of fast-rotation turbine it might even be effective reaching (with the wind from the side) even with the prop decoupled (if you adjust the angle carefully). This was shown in the 1930's by Moore Brabazon with his Solent Redwing class boat. However, going directly to windward it is likely to be unpleasant and what is meant by "authoratative" progress? It needs to be related in some way to the speed of the wind prevailing at the time.

Peter
From what I have seen there is no confirmed speed data on going directly to windward. I tried to estimate the speed you achieved on your cat but the frame follows the boat so you cannot work out speed by movement through the frame. A rough estimate is 2 to 3kph. By authoritative I mean two to three times this. Something that would challenge a small sailing boat in VMG.

I believe I have already made considerably higher speed than your boat achieves in the video clip. My aim is to provide GPS data backed by video evidence of the result. Until someone can produce the same sort of evidence I will hold the turbi-prop record. Maybe someone will care to take a shot at that record. I have already made improvement suggestions.

It would be wonderful if Michael proves to be on a valid path. That is the sort of thing that could spawn a fleet of new sailing craft.

Rick

[Guest625101138]

Originally Posted by Windmaster

Yes, but if you store up energy to use later that's not much of a challenge is it, because you can use any kind of setup and it does not have to be efficient. On the other hand gathering your energy and using it at the same time against the wind is the truest test of your components and their efficiency.

Anyway, all this talk of efficiency makes it look as if going directly against the wind powered by the wind is a borderline activity which might "just work" if you get everything right and you make this or that subtle adjustment of pitch, gearing and get the "correct speed of wind".

I don't find this to be the case. Using the way I have developed, it is simply no problem going directly against the wind and there is so much force available that these subtle nuances of adjustment seem trivial. I have given enough clues already of the best way to do it!

Peter
Two things:
1. On the batteries I am not suggesting you sit anchored storing up energy and then take off. I am suggesting you store energy on all points of the wind and use it for continuous forward progress. Why do we need the "truest" form! It is arbitrary nonsense that constrains the potential. I could argue that variable pitch is not the "truest" form - you cheated in comparison to what I have done with added functionality. It gives a practical advantage over a range of wind speed and points of wind.

2. The ultimate speed is limited entirely by the turbi-prop efficiency and the hull drag. With a low pitch prop like I originally used, effectively a lower gear, my boat was hard to hold against. It was pulling me forward. In some gusts the water around the the prop was churned white when I was holding it on the shore. This is tremendous power, certainly above 1kW, producing considerable force. So it is not marginal. But force does not translate directly to speed. The speed is limited by the gearing. The closer the prop pitch is to the turbine pitch the faster the boat goes. The fact that I could make good progress in gusts with the 625mm prop confirms my efficiency calculations. The turbine and prop are both getting around 80% in the stronger wind. However the prevailing conditions were not steady enough for me to actually make continuous forward progress - I lost ground overall.

As far as borderline goes I think you would struggle to convince anyone with your video clip that you would not find it easier to simply put a paddle in the water without all the mechanical gear and make twice the speed. At 2 to 3kph it is not convincing of anything more than a curiosity. As I stated earlier, my target is to challenge the speeds attained by sailing dinghies. I can easily do that now with pedal power in any conditions.

Rick W

[Windmaster]

Originally Posted by Rick Willoughby

Peter
A rough estimate is 2 to 3kph. By authoritative I mean two to three times this. Something that would challenge a small sailing boat in VMG.

Until someone can produce the same sort of evidence I will hold the turbi-prop record. Maybe someone will care to take a shot at that record. I have already made improvement suggestions.

It would be wonderful if Michael proves to be on a valid path. That is the sort of thing that could spawn a fleet of new sailing craft.

Rick

I think you're a little wrong with your 2 to 3kph estimate, but even if it was, it doesn't say anything without comparing it to the windspeed at the time. You just can't talk about speed without knowing what the wind was.

How amazing to claim you hold a record - just because you say so!

In that case I hold the record - because I say so! (and so do many other people)

Incidentally, as a non-sailor maybe you don't understand the variability of the natural wind. All of the time, the wind varies by as much as 50 percent between gusts and lulls - there is no such thing as a "steady wind" - added to this the wind has a great deal of turbulence within it. This is where some theorists go wrong. They do tests in a wind-tunnel, which is perfectly valid for aircraft, but it's not valid for sailing. This, in my opinion was the cause of the "Team Phillips" disaster.
For confirmation of what I say, it's a good idea to study some of the windspeed graphs for various locations.

I have no idea whether Michael is right or wrong about the ducts. If he is right then it certainly is a very exciting breakthrough, which I for one would not want to deny.

[Windmaster]

Originally Posted by Rick Willoughby

Peter
Two things:
1. On the batteries I am not suggesting you sit anchored storing up energy and then take off. I am suggesting you store energy on all points of the wind and use it for continuous forward progress. Why do we need the "truest" form! It is arbitrary nonsense that constrains the potential. I could argue that variable pitch is not the "truest" form - you cheated in comparison to what I have done with added functionality. It gives a practical advantage over a range of wind speed and points of wind.

2. The ultimate speed is limited entirely by the turbi-prop efficiency and the hull drag. With a low pitch prop like I originally used, effectively a lower gear, my boat was hard to hold against. It was pulling me forward. In some gusts the water around the the prop was churned white when I was holding it on the shore. This is tremendous power, certainly above 1kW, producing considerable force. So it is not marginal. But force does not translate directly to speed. The speed is limited by the gearing. The closer the prop pitch is to the turbine pitch the faster the boat goes. The fact that I could make good progress in gusts with the 625mm prop confirms my efficiency calculations. The turbine and prop are both getting around 80% in the stronger wind. However the prevailing conditions were not steady enough for me to actually make continuous forward progress - I lost ground overall.

As far as borderline goes I think you would struggle to convince anyone with your video clip that you would not find it easier to simply put a paddle in the water without all the mechanical gear and make twice the speed. At 2 to 3kph it is not convincing of anything more than a curiosity. As I stated earlier, my target is to challenge the speeds attained by sailing dinghies. I can easily do that now with pedal power in any conditions.

Rick W

1.
I thought mentioning "the truest form" would appeal to you since you are a perfectionist.
2.
Your second para is a little contradictory, on the one hand you say you observed "tremendous power" and on the other hand you say that due to the conditions "not being steady enough" (refer to my previous post) - you lost ground overall. When will the conditions be "steady enough"?
3.
In the third para you are trying to ridicule my video. I note that you don't hesitate to deride other people when you get the chance. I have had plenty of opportunity to heap scorn upon your statements so far but I have refrained from doing so because I want to be fair. Fairness is something you don't have any regard for. You only criticise others and claim you know all the answers. It's not a very pretty picture.
You criticise my video, but at any time does it show the boat "losing ground"? - which is something you said your boat did (or does).
.......

[Guest625101138]

Originally Posted by Windmaster

I.....
In that case I hold the record - because I say so! (and so do many other people)

...y.

I have GPS proof of what I have achieved. At this stage no video evidence to back it up but that will come. You have nothing to prove the speed achieved. Your video clip does not have any easy reference to even estimate the speed accurately.

I doubt that there will be enough people inspired by the idea to run out and build boats so there will never be class racing with turb-prop boats; at least not in the foreseeable future. For the few people who play with them the basis of performance comparison has to be quantitative and easily compared without side by side comparison.

I have been through similar debates with pedal powered boats. That is why I regularly show GPS plots of what can be achieved. A few others like Mike Lampi does this as well. If you want to get better you have to measure and compare. Like I said you show me any GPS data or independently timed data and the record can be yours. Otherwise your claim is hollow. It is like the guy in his 24ft heavy displacement boat claiming he did 240nm in a 24 hour period.

What makes you think I am not a sailor? My avatar is one of my old sailing photos.

The wind variability is much greater near land than offshore. The greater the variability the more you will benefit from an energy storage system. So in very confined spaces like a river the battery storage will prove far more practical. You seem wedded to the "purity" of a mechanical system, irrespective of complexity, at the expense of practicality.

There is nothing magic about sailing directly into the wind. My first tests were done in 1983 but I was not in the habit of recording them photographically back then. You seem more in love with the wow factor from the ill informed than a practical working solution.

The fundamental physics strongly favour decoupling. The power required to push a boat is the cube of the speed or higher power if wave making comes into play. Consider where the wind gusts and the turbine spins up to double the power. You get something less than a 25% increase in speed due to system losses. Why not maintain a steady speed and store all that extra energy so you can hold your speed when the wind lulls.

If you take this basic relationship and do an average speed for a typical wind profile you will find you can tolerate significant losses in the electrical system and still come out on top over the best mechanical system that does not have energy storage.

Rick W

[Guest625101138]

Originally Posted by Windmaster

1.
I thought mentioning "the truest form" would appeal to you since you are a perfectionist.
2.
Your second para is a little contradictory, on the one hand you say you observed "tremendous power" and on the other hand you say that due to the conditions "not being steady enough" (refer to my previous post) - you lost ground overall. When will the conditions be "steady enough"?
3.
In the third para you are trying to ridicule my video. I note that you don't hesitate to deride other people when you get the chance. I have had plenty of opportunity to heap scorn upon your statements so far but I have refrained from doing so because I want to be fair. Fairness is something you don't have any regard for. You only criticise others and claim you know all the answers. It's not a very pretty picture.
You criticise my video, but at any time does it show the boat "losing ground"? - which is something you said your boat did (or does).
.......

Peter
I am far from a perfectionist. I seek optimum solutions. I have seen how arbitrary rules and fashion distort solutions and result in sub-optimal outcomes. Maybe uncompromising but not a perfectionist.


If you have been following, I have done two trials. One in very heavy wind and one in lighter conditions.

The first time I had a prop with 300mm pitch. This had no trouble making progress in any direction but I had limited control.

On the second test, with a 625mm pitch prop, I could achieve a very good speed reaching - rough estimate was above 10kph but I did not want to risk dunking my GPS on the second test. (I thought I was lucky it survived the first.) With this prop the boat would get in "irons" when the windspeed dropped. I did make some good progress in gusts but on average I went backwards because there were longer lulls than gusts. I eventually worked out that I could turn side-to to avoid going backward fast similar to what a cat does if stalled.

It is easy to make a boat that will make progress directly to windward. It gets harder to make something that offers practical advantage over simple human power or sail. Why would anyone bother with the complexity if there is no merit. Your video dates to 1995. It is now 14 years on and there has been no further development. You are trying to goad others into an idea that you are stalled on. When I propose ideas that make it more practical you suggest it is no longer "true" to the concept - it is cheating. You cannot get past the wow factor and move on to more practical options.

I am interested to follow what Michael is doing because he has made some interesting observations. I have already learned that a venturi can beat Betz limit from his work. This is significant. I still have doubts that he can make a dragless venturi but it will be interesting to research this.

Instead of goading me why not get to and make an improved version of your "true" system that you can get some concrete data from that betters what I can do with a cobbled together craft from bits I have in the garage.

Rick

[MPraamsma]

Boy, you guys really get into it, I feel like I'm watching a fist fight beteen Einstein and Maxwell...LOL. I feel both of you are correct, but are approaching the problem from different angles. Peter seems to have taken the intuitive direction by having many large area 'wind paddles' that can be set to whatever pitch moves the vessel at the best rate, Rick seems interested in perfecting the foil and prop combination to maximize efficiency. Both these methods can work, but as we all know now, and I have proven to my satisfaction with my own tests, there is a ceiling to this due to the issues I think I have covered amply elsewhere. I agree with Rick that storage is mandatory, and then carefuly parsing the power as needed, is the only logical solution other than sending the excess to some kind of 'wastegate'. Even when sailing a conventional sailboat a certain amount of power is stored in the additional heel of the boat and is recovered as it rights itself to the nominal attitude after a gust. If this didn't happen, the incidence of broken masts would be higher because there would be no way to absorb power transients.

I'm continuing my story for a moment for the benefit of those who haven't read all the posts, and I would like to show my final configuration with some introduction of the train of thought. The attached PDF shows my first attempt to prove to myself and others that direct windward progress is possible. I did this before I stumbled on this site, so you can see the commonalities of our thinking even when independently derived. I was so enthoused creating this thing (I made this thing in a single weekend) that I forgot to check if others had tried it before. It did however force me to think the whole thing through on my own before I knew what difficulties others have had.

This model was very responsive, almost jumping off the starting line like a rabbit (I ran it on the dock first and had to rescue it many times from zipping off the edge into the water), but as you know it only goes so fast and no more. At first I though the prop was not optimised for windmill use (it is not possible to buy the correct model prop, so I had to run it with the trailing edge leading), so that made me think all that was needed was the correct setup (which I would have to build myself). That was the reason I made the full size version I will discuss on the next post.

[Windmaster]

Originally Posted by Rick Willoughby

Peter


I am interested to follow what Michael is doing because he has made some interesting observations. I have already learned that a venturi can beat Betz limit from his work. This is significant. I still have doubts that he can make a dragless venturi but it will be interesting to research this.


Rick

Yes, I agree, Michael is doing very important work, I hope he can get some success with it.

Also, I liked the little windmill cart - a very good demonstration.

Also, (believe it or not) I'm not against storage - its a good idea. But that doesn't mean "direct" is not interesting in itself.

Unlike some, I am always willing to give credit to others and I have supported other people in the past whose ideas I believed personally were wrong or misguided (but I didn't tell them so).

What does annoy me is ungentlemenly conduct, arrogance, and poking fun at other peoples efforts.

[Guest625101138]

Originally Posted by Windmaster

Y........
I have supported other people in the past whose ideas I believed personally were wrong or misguided (but I didn't tell them so).

.......

I do not hesitate in challenging someone by offering an alternative view if I believe they are wasting their time. I realise some people need to make their own mistakes to learn but it would be dishonest to stand by smugly applauding what I believe are misguided effort.

If you go back through the various threads on this topic I have often challenged Michael on what he is doing. But he offers a considered and alternative view. He has still not convinced me that he will produce something uniquely better but he has given it a lot of thought

Originally Posted by Windmaster

........
What does annoy me is ungentlemenly conduct, arrogance, and poking fun at other peoples efforts.

I am giving you a blunt and honest opinion. Grown ups take that as a challenge or laugh it off. I have three adult sons who constantly give me their often blunt and honest opinions.

If you look at my first efforts with pedal boats you will see that they had good cause to have a bit of fun at my expense. A number on this forum have belittled my efforts as not being "real" boats while playing with bathtub toys in back yard pools or contemplating anti-social fuel guzzling monstrosities. Rather than accusing me of ungentlemanly conduct, suck it up and take it as a challenge to get on and do better than I can demonstrate.

Development of your turbi-prop boat has stalled. Surely after 14 years it is time to get on with the job if you firmly believe the idea has any merit beyond - wow, look this boat can go directly into the wind. So what, any first year applied maths undergraduate could provide the proof if challenged.

Rick W

[Windmaster]

Rick
May I remind you that you are the one with something to prove.

You are arriving at this party late - by 14 years.

I have a video of what I did 14 years ago. Whatever you do now - I was 14 years ahead of you!

To say that my project is stalled is a big assumption. You only know what I have chosen to tell you.

[Guest625101138]

Originally Posted by Windmaster

Rick
May I remind you that you are the one with something to prove.

You are arriving at this party late - by 14 years.

I have a video of what I did 14 years ago. Whatever you do now - I was 14 years ahead of you!

To say that my project is stalled is a big assumption. You only know what I have chosen to tell you.

That fact that I demonstrated it in 1983 is not something I can prove but I realised then it was possible albeit marginal.

If you want to be clandestine about it then that's your choice. I am open and honest with what I do and will provide quantitative results.

You offer a 14 year old video that shows marginal operation and nothing quantitative. If you do not measure you will not improve. Any other claims you make about what you are choosing to tell us is hot air until you provide some data. If you want to be secretive about it then why participate in an open forum. Your motives have to be questioned.

Rick W