The Wind Powered Sail-less Boat

For the DDWFTTW boat the turbine in the water extracts power and the mechanical system delivers it to the air propeller. The water is being slowed down a little relative to the boat near the turbine and the air is being accelerated backwards a little relative to the boat. In absolute terms the air slip stream is moving a little slower relative to the water and there is a water slip stream moving in the direction of boat travel.

You might find it easier if you think of the boat clawing its way against a strong current in still air. This is the exact opposite of the upwind condition where the water is static. The current tries to force the boat backwards but the air drag on the big prop and boat superstructure slows it relative to the current. This causes the turbine to spin because the water is now flowing past it and begins delivering power to the propeller and the propeller starts to drive the boat forward through the water. The flow past the turbine increases and the power flow to the turbine increases. This is not as hard to imagine but the boat is now moving in its direction of travel faster than the air, which, of course, is not moving at all.

Now flip this frame of reference so the air is moving over the water.

There is one of the Goodman's videos showing his DDWFTTW on a treadmill. Initially the car is tethered as the treadmill comes up to speed and the prop starts spinning. Once up to speed the car begins to claw its way up the treadmill with power being delivered to the wheels and these in turn driving the prop. The prop generates more thrust than the drag on the wheels by virtue of simple gearing.

Rick W

 

It's taking me a while to grasp this.

Where can I find more information on Goodman or see other videos? I did a search, and only found the one outdoor video, nothing else.

 

if its a flywheel then the energy it takes to alter angular momentum is seriously going to foul up your day
one reason flywheels have been nixed in cars is catastrophic failure and random system re stabilization over rough terrain
rough terrain and waves are spelled much alike
but they sure sound similar
same goes for the blades if they find themselves spinning a little fast
might take more energy than you think to redirect them
boat might have a mind of its own when it comes to direction
dont let me discourage you though
I cant wait to see how this pans out
would love to see an animation eventually
B

 

I would have thought the trick would be accomplished on ice

Im always skeptical of fttw runnin
the extra energy has to have been stored in a spinning something and will not last long
auto gyro might help out some
but its a stretch to say its wind powered and going faster than the wind if its storing that power and then dumping it into the system for a short stretch
on a tack
no problem
a close reach
Im a believer
on a dead run
I need going to need more convincing
sail power alone with no storage device
according to that little darling mentioned previously
the ever handy first law of thermodynamics
that and water resistance
makes it highly unlikely

all that being said
I hope some one does it just to stand science on its ears
best
B

 

Curtis
This is not the Goodman video but it is similar:
http://www.youtube.com/watch?v=kWSan2CMgos&fmt=18

I think this is easier to wrap your brain around. Providing the gearing is right the wheels will pump power to the propeller and it climbs up the treadmill through reacting on the air. It is not moving all that fast through the air but it is really motoring quite fast on the treadmill.

On the outdoor demonstration it moves too fast to see what is going on.

The proportions on this are better than Goodman's vehicle because it is very light with simple gearing and has a relatively huge propeller.

Once you get this concept on the treadmill you simply have to shift the frame of reference so the wind is moving relatively to the land and the vehicle is advancing faster than the wind. It is a matter of gearing. If the propeller was replaced with a low geared winch drum tied to the front of the treadmill then you would easily understand the idea. You would say it was no big deal.

With the boat you replace the wheels with a water turbine that is simply spinning as the water goes past and pumps power into the air turbine.

Rick W

 

dont get mad at me for being a skeptic
but several things
the fluctuations if wind velocity could easily account for the tell tails occasional backwards flutter
that and its proximity to the turbine
also there is energy stored in the turbine that although may for short periods allow for fttw speads
on average
I dont see the system breaking any speed records
stick that thing in water
were pitching and rolling
are energies that will effect an alteration in the axis of rotation and angular momentum
and given that on analysis those energies will need to be deducted from the forward energy of the craft
then Ild say this is not the magic engine I was hoping for
was a fun little gizmo though
B

 

Im loving this thread
90% impressive
10% not faster than the wind

the answer is in a spinning something
but what Im dying to see
B

 

Boston
What I ask people to do once they understand that it DOES work and does not defy any grand laws is make a correcing post just so people that read through these things take a bit more time to understand it rather than not taking any real time to think it through.

If this is not done we just go on with this forever. It is basic physics. Sail powered sail boats have been going faster down wind than the wind for as long as I can remember. And that is in terms of VMG in the direction of the wind. The only feature of the propeller/turbine combination is that it enables DIRECT downwind faster than the wind.

So when the penny drops please take time to post your flash of insight as Tcubed did on #220 here:
http://www.boatdesign.net/forums/pr...-how-many-out-there-they-viable-14182-15.html

There are some dumb ideas around and some will not work but this is a somewhat useless idea that does work.

On water you have the advantage of zero friction initially but if you go to the earlier posts you get an idea of the scale of things required to make it work for a single person boat.

Rick W

 

there is roughly a one percent loss of energy in a simple gear
a magnetic gear has less but you have to run it in a vacuum to get it to zero
and even then there's arguments to say its not zero
so I have to wonder if a gearing system on a indirect turbine to prop application would be able to eliminate all the friction possibilities plus find energy in the rotation some were to add to the forward motion
I think its bordering on perpetual motion
a sail powered craft runs before the wind by virtue of resistance to the wind
when that resistance reaches zero as the craft approaches wind speed
were you going to get more energy from
inquiring minds
want to know
B

 

This is far from perpetual motion. The losses are quite high. If you look through the series of videos on YouTube covering DDWFTTW you will see different vehicles and how they perform. Keeping the vehicle light reduces rolling drag and the propeller relatively large and low pitch (spinning fast) helps the propeller efficiency.

I doubt that anyone could make a system work with windspeed lower than 2m/s because you simply cannot get the required efficiencies. You need this sort of relative movement between ground and air to overcome the loss.

As far as conventional sailing boats go you might gain some insight on how they perform downwind on this thread:
http://www.boatdesign.net/forums/sailboats/tacking-downwind-faster-than-wind-24761.html

Rick W

 

one of the best ways to learn is to be wrong and stand corrected
Im all ears my friend
convince me
maybe I was to quick ( been known to happen before )
I studied physics for a long time and Im just not seeing this one
oh doesnt mean I cant be completely wrong about this
but so far Ive not read a compelling argument
I certainly didnt mean to offend anyone
I actually found the subject really interesting
maybe I missed something
were talking about a simple spinning turbine
either connected to a shaft driving a prop
or simply spinning freely
being able to drive a watercraft faster than the actual wind
no batteries no storage devices

(Tell Tails only read apparent wind)

Im already to be convinced and I will print one huge retraction
send me a video of a boat
and maybe a few details about how it does it
and how they overcome energy loss through random alteration in the angular momentum of spinning components brought on by things like heeling pitching rolling and the like

( takes a lot of energy to redirect the axis of rotation of a gyroscope )

I read this thread word for word
the one about an electric generator operating in port, charging batteries made the most sense
course you might do the same thing with enough solar panels and eliminate all the gyroscopic forces
but thats stored wind power
and given the energy loss of the basic charging system
not real efficient

 

Boston
By the way I do not expect payment for your education just a post acknowledging that it is quite feasible and does not defy any of the known laws.

Rick W

 

hey Rick
as far as into the wind is concerned
I didnt mention it cause Im sure its possible
but I really would love to read your research on going faster than the wind on a dead run
I would think you'ld hit a dynamic equilibrium that equals the wind speed minus system friction ( drag )
the air turbine wont spin any faster than air speed allows minus friction
and the water turbine wont spin any faster than the water speed allows minus friction
neither have energy available at dynamic equilibrium
and drawing energy from either only makes that equilibrium a smaller fraction of the ttl energy available
soooo
how does the water turbine add energy to the system with out offering so much drag as to overcome any benefit

Ill get back to you tomorrow
I gotto get going
nice intelligent conversation though
hope all it well
B

 

your on
and I owe you a brew for that one as Im laughing my *** off
tell you what
if Im wrong
you tell me your favorite pub
and Ill telli it up and get you a brew on me
k
gotta go
B

 

Have you looked through the videos of the land vehicles on YouTube? Do you believe what is being shown on the treadmills? Are your physics/maths skills good enough to write the equations of motion you see in the application? I need to have some understanding of your level of knowledge so I can peg your education correctly.

Once you have these sorted out post them here and I will check your answers. We can than move on to the land vehicle on fixed ground in a moving air stream. Same thing - post equations of operation and we will move on to the boat situation.

If you know how levers work then you have the basic comprehension to grasp this. I guess there were many who could not believe Archimedes could lift many times his own weight. We are simply dealing with rotary levers here. Some aptly refer to them as screws.

If you want to cheat then Joakim has posted the physics above. I have given precise numbers for a system that will work for a boat based on precise modelling of the foils and hull drag.

If you are really hung up about the system losses with a boat. What you have dome is taken energy from water by accelerating it in the direction of travel and transferring it into the air by slowing the air down a little. So there is evidence of energy being given up. If it was perpetual motion it would be like stopping the treadmill and seeing the thing continue to advance forever. This will not happen. It requires the relative movement of air over ground or air over water.

Rick W