The Wind Powered Sail-less Boat

The answer is very simple - GEARING or a rotary lever.

Power is force X velocity. Going downwind, the water past the turbine has to be faster than air past the propeller. So if gearing is set to allow the air velocity to be say half the water velocity the force generated by the prop will be twice the force applied to the turbine. The excess force is available to overcome system loss and hull drag.

In practical terms the propeller is not very efficient because the airspeed is quite low so it is not in an ideal operating regime. A boat speed of 4 or 5 m/s is quite fast and is going to need a significant force even with a slender hull so the propeller ends up being a monster in relation to the boat. The scale of propeller to vehicles you see in the video provide a good indication of what is required.

Rick W

 

theoretical physics
I just patented plasma insulation
although most of the time I work as a general contractor cause it keeps me fed

the numbers on free spinning wind turbines were dreamed up in the forties
and should be the same as the numbers for a gyrocopter

and I dont really see anything special about a horizontal gyrocopter being pushed uphill by a fan
there doesnt need to be any gearing to the wheals to make that happen

so rather than try and remember the friction formula for an incline plane
and go through all that rot of figuring out the gear friction and turbine speed/wind speed bla bla bla
I think Ill just leave the burden of proof on you
my beer your burden
Im just going to sit back and await convincing
so get cracking cause I might just accidentally drink your beer money
accidentally

as for crunching numbers
I only do it when I have to, and I tend to get paid for it ( if Im lucky )
although
I was playing with Faraday's theorem
E=Hv
found the common denominators with E=mc2 and came up with

Hv
---- = m
c2

if you play with it a little, it basically defines mass as a function of speed "or" frequency

or

being the key operative

so I think Ill understand what ever you send me

but
dont be mad at me if I start asking for considerations of friction with in system
also there is a definite loss of forward motion within any system that demands the redirection of gyroscopic forces
and its a lot of energy
so there could be a reason these things are land models
and not sailing models
as that random motion of the system can be more easily controlled

think of me as a beer buying skeptic
Im not closed minded
just not convinced

I gotta go
B

 

The point is there IS gearing to the wheels and NO fan involved. It is not a gyrocopter. It is a propeller extracting energy from the treadmill through the wheels and applying force to move the vehicle against the treadmill. Very simply it is gearing.

I have provided a series of images that if you work through you will gain understanding. All you need to know is:
Force = Power X Velocity
Turbine has an efficiency of 85%
Propeller has an efficiency of 45%
Mechanical efficiency is 94%
Boat drag is a function of V^2 and is 60N at 3m/s

Current where shown in the attached is 4m/s.

Wind speed where shown is 3m/s.

Rick W

 

The key you have to understand is that there are two fluids with a velocity difference. Reducing this velocity difference gives you energy.

A very simple analogy is shown in the attachment. You can always replace the rope fixed to floor with a transmission in the "car", which is connected to wheels.

Then you can replace the whole rope with another pair of wheels, which touch the ceiling and are geared to the other wheels touching the floor. Then you are no longer limited to the length of the rope. As a home work you can derive the equation for the speed of the car as a function of the gearing.

When you do these calculation, you are probably not worried about efficiencies, friction and energies, since you don't mind what moves the ceiling and you can assume no slip for the wheels.

Do you agree that the car can move faster than the ceiling (wind) without being perpetual motion. What is the difference between this example and turbine/propeller combination?

Joakim

 

Rick, thanks for the link to those vids. After watching three of them, I wrote to the guy who posted them, with a couple of comments.

First, I said that some skeptic might think that the whole cart was being blown along by air pressure, and suggested he do a comparison demo with the propeller still on the cart, but disconnected from the gear drive.

Then, I commented that he needed to include scientific measurements, specifically the windspeed at the cart's location, and the rotational speed of the wheels and their diameter. This would allow a simple calculation to compare vehicle speed against windspeed.

I think the biggest problem with understanding this is the way our brains function. Our brains are wired to comprehend natural phenomena just fine and to learn to use that understanding. For example, a person with no training or prior experience can get into a canoe or kayak on moving water, and within a couple hours will learn on their own how to ferry the boat.

Wheels cause problems, because nature didn't invent them. Sure, logs and rocks roll down hills, but take that rolling object away from contact with the ground, and it becomes counter-intuitive. The very most basic: the gyroscope. This one-piece wheel and axle assembly consists of (count 'em) one moving part, in simple rotation, yet causes more brain-spasms than a political campaign (well, maybe some campaigns, anyhow). We just aren't wired to comprehend things that appear to defy gravity or seem to have a mind of their own. Bicycles and motorcycles turn opposite to the way you steer them. The list goes on, and it's no wonder people still believe in magic.

Nature does include flying things like birds, and we can barely comprehend those beyond the level of "tastes like chicken."

So, it's no wonder that DDWFTTW is so controversial. It just doesn't fit in our brains.

I've got a square peg and a round hole in front of me, and I'm seeking the properly sized hammer.

 

Curtis
Gyroscopes and bicycles staying upright are far more complex physical systems than a turbine driving a propeller to go faster than the wind over water. All you need to know is power equals force times velocity. No need to get into the complexity of corioli effect.

The difference with the bike and the gyroscope is that most toddlers have seen a spinning top and most preschoolers have ridden a bike. They do not understand it but simply have experienced it. The vast majority of people cannot explain why they work. Have a go at telling a complete skeptic that a top can stand upright as long as it is spinning without any external force applied. If you can do that then tell me about gravity. What is this?

We have the situation where the skeptics out there cannot see a monster fan overcoming a little drag on a small hull using power coming from a water turbine and yet most have stepped on board a 500t aircraft that has held itself aloft in that same air. Air is able to produce huge forces providing there is enough area and a bit of velocity.

The analogy that Joakim makes with a vehicle having wheels top and bottom and sandwiched between two surfaces is a good one. I have attached a couple of slides that show this analogy. The direction and speed of travel is solely dependent on the gear ratio. It is not perpetual motion because when the plate stops moving the vehicle will certainly stop moving.

Rick W

 

I think the issue of wind direction is confusing some people -- it clouds the issue. I understood FTTW better when I completely disregarded wind as a factor in the operation of the device. Just pretend it's dead calm. You push the thing a little to get it going, and the wheels speed up the propeller, which pushes it faster . . . it'll accelerate until drag overcomes further acceleration. This will be the basic case in any wind condition.

 

well in answer to the three questions in the order they appear
Ild have to say
maybe ( Ild have to see your math on it )
no
and no

 

I have framed the problem in a simpler form in post #66. I would expect a grade 5 student to be able to work this out. Once you have got the maths sorted for both cases and provided the correct answers I will add some drag into the system.

Rick W

 

Curtis
You have now invented perpetual motion. The system does not work unless the wind is moving relative to the water. There has to be a source of energy input.

Work out the answers to my two problems in post #66. See if you can get correct answers quicker than Boston. We will see who has mastered 5th grade maths. What year are students taught algebra in good old USA?

Rick W

 

exactly
but there's no potential in that for fttw or you would have perpetual motion
all your doing is storing the push you put in the system in the gyroscopic action of the propeller
and then watching it wind or oscillate down to equilibrium
I think its the oscillation that's got some folks going over these models

as far as the tread mill gizmo
you are right in that I had misunderstood what they were showing

and I appreciate you explaining it to me
but
but Im still not finding it very convincing
had they not inhibited the forward motion of the device and stored up a gyroscopic energy in doing so
it would not have even developed that cyclical effort it made to find equilibrium
an equilibrium that would not have represented more than the energy of the system minus resistance

Best
B

 

wait a minute
I didnt know there was going to be a test and a time trial
you gotto post this again
and ring the bell to get us started
Im not ready
I need a pencil
wait
wait
wait
ok
dam
now were is the site again
something about # 66
what the hell is 66
isnt that some twisted sexual position or something
hang on and Ill ask the girl
might take a while
be right back

 

I will award reputation points to whoever posts the right answer first. Here is your opportunity for a big lift in your reputation.

Time starts now. Order of posts will be taken as the earliest finished and has to be the correct answer. You can have as many goes as you like. I will mark the result next week. No cheating using other threads to elicit answers. It has to be your own work

Rick W

 

well I didnt see any equations to look at or work out
and Im still thinkin burden of proof is on you
so Im going to sit here and enjoy a cold one
and await the magic equation
its not up to me to dream it up
I dont happen to believe in it
the sum of speed a and speed -a arent going to equal anything more than speed 0
in a system were there is a floating object
a current moving from left to right
and a wind blowing right to left
a drag based propulsion system
will find an equilibrium somewhere in the middle
and it wont be any faster than either individually
nor will its potential energy exceed the sum of the two

if you have something that shows this
Im dying to see it
but so far you guys keep asking me to build a mathematical model of the system
and its not my system to prove
Im not really buying it
soooooooo
Im going to get some more beer
talk to the girl some more
and see what shakes loose
cheers
B

 

energy out (A)
energy in (B)
friction F

A =B-F