The Wind Powered Sail-less Boat

B

Rick

gearing and leavers add resistance to the system and play with mechanical advantage
they dont actually add energy
matter of fact ttl energy is reduced as the law of conservation of energy is effected by friction

this responce is completely incorrect
no beer for you

90% efficient is a far cry from 110%
and near as I can tell your talking about a system that is more than 100% efficient and it doesnt exist
its called perpetual motion

on a dead run
once a turban powered vehicles speed matches wind speed
the apparent wind at the turban is 0
all it can do at that point is add drag
same goes for he propeller
so equilibrium must be bellow the environmental characteristics
no way that system will exceed wind speed
the more I think about it the less convinced I am
the propeller is no longer powered by the turbine and also adds drag
partly due to having to act against mechanical advantage of the turbine
and partly due to the water resistance
system does not work

oh you will get some motion out of it
but it wont achieve on a dead run fttw speeds

now if you are on a reach then the resistance to sideways slipping and the apparent wind combination will do you some favors
but not on a dead run

speaking of dead
Im tired
need more beer
and stuffed
( had a nice dinner ) ( thanks Bree )
so best
hope all is well
B

 

Have a look at this video:
http://www.whatheck.com/2007/02/sailing-directly-downwind-faster-than.php

Cheers.

 

You are not reading the posts! There is no problem for the AIR propeller with the apparent wind being 0. It is a propeller pushing air bacwards, just like a airplane propeller when you accelerate starting from zero apparent velocity.

The turbine in the WATER is in this case turning the propeller in AIR not vice versa. The turbine has a lot of apparent velocity, more than the wind speed, if you go faster than wind.

You are thinking this as a sail, which it is not. And actually you can go faster than wind downwind with a sail as well (ask the downwind VMG vs. windpseed from ice sailors), but not without jibing.

If you really know theoretical physics, the answers asked should be easy for you. Actually I think High School physics (at least in Finland) should be enough to solve these.

Joakim

 

Perhaps seeing the DDWFTTW (hope it went right) as an entropy machine is easier (shows how twisted is the way I think) way to understand this. So this turbine/propeller promotes entropy btw the fluids and/or medias and by doing it "borrows" a bit of the energy to accelerate itself to higher energy level until the state of the equilibrum is achieved (in theory anyway) or the hand of god (man running after the machine) stops the process

 

no Im reading the posts
and I saw the video
Im just not buying it
not trying to piss any one off
just not a believer in perpetual motion
the propeller isnt going to suddenly change direction and add energy to the system
the same mech advantage that drives the wheels off the propeller is the same mech disadvantage that slows it down once it reaches some percentage of wind speed

if this thing is for real
were are the wind tunnel tests
were are the wind speed numbers
were is the vehicle speed numbers
were is the schematic of the device
and were is the data sheet showing average results over number of tests
and were is the confirmation study by an independent researcher

with out the scientific data for all to see
its just a toy rolling down the road
a road
thats bound to not be level
which no road is
and will definitely skew
what
a film of a completely arbitrary non scientific test
and subject to indiscriminate and random winds
with no data stream delta T
please


actually the second law of thermodynamics pretty much covers this one
energy ( heat ) will not flow from a lower state to a higher state with out additional energy ( work ) being applied

if this thing were real we could quit drilling oil or burning coal
and we cant
I wish we could
but it doesn't work

Ill call in a beer at the bar of your choice for each of you guys if
you can show me the scientific data I have requested
I want real data
confirmed
name of university conducting
principals involved
any citations included
supporting articles
publisher
wind tunnel test showing 100+% energy output
an exact description of the device
a full schematic
both raw data and full data analysis
in addition

basically I want to see some scientific data instead of a few renderings and toys that dont prove anything

if there is an actual scientific study this important
then there will also be a confirmation study
Ild be slacking if I didnt take a look at it to
normally they include

confirmational studies verifying previous analysis
name of university conducting confirmation study
principals involved
authors of citations comments if any
authors of supporting articles comments if any
publisher and name of publication
confirmed wind tunnel test showing 100+% energy output
confirmational analysis of schematics
confirmational analysis of test process
bla bla bla

basically I want to see the hole study before I start buying you guys beer
and Ill apologize for having doubted you
all you got to do is bear the burden of proof for what you are saying
Im not trying to be the ogre under the bridge
hell Im waving drinks at you guys hoping you can cough up the data
I just dont think it can happen

on a dead run
a wind powered vehicle
will not go faster than the wind

 

Rotor musings. If a rotor's shroud had radiating supports upwind of the blades blocking the true wind at intervals to change angle of attack at the right Strouhal number, would the blades be virtually flapping in the breeze. If true wind increased in the shroud, blades would need less twist and could have more pitch, rotating lift vector forward for more torque, even at high tip speed ratios. This line of thought requires belief in the Katzmyr effect, hysteresis, negative drag which all have a tenuous place in my mind. The potential stall of the intermittant high angle of attack is avoided by a negative one in the apparent wind of blade travel behind shroud supports maintaining attachment. Would there be any gain in the real world?

 

impresive post there Luny
I had to go look up the Katzmyer effect
way to make me think
I found a confirmational study on an original done in the twenties
basically he is looking at the effects of joining a wing and an oscillating flow in harmonic sympathy and seeing if he can add amplitude a to amplitude b and get a+b
which should work in a kinda twisted kinda way since he is not actually dealing with a wave form in the wing
I think its going to very pleasantly confuse this issue
way to go
I really liked the article
thanks
B

oh
it would never work outside a controlled environment as you suggest with the question

actually Im working on something like this concept with the next generation of plasma insulation
but so far its just a bunch of theory

again
nice post
way to track down a relevant article and note the tenuous nature of the concept
there wasnt much on Katz in the university data base
how is it you are hip to that work
do you do some studies in that field

 

I am just a causal sailor with lots of curiosity and some ability to knock things together in the real world but little theoretical background. Bird flight observation was main inspiration for this concept. You have saved me from the work of a prototype but the mind runs on.

 

well it took more than the casual Cat to draw on a near hundred year old study by some Russian scientist that barely shows up in several university data bases
hats off to you
B

 

my point exactly when I said

tacking (Jibing) involves being on a reach
maybe I should have been more specific and said broad reach
but still
I think I got this one covered
although

was a poor mention of the physics of an object moving through an arc require it to be accelerating or at least not decelerating as fast
basic centripetal force requirement
( newton kids, anyone remember him, funny little hat, gravity, laws of motion guy, Newton )
basically you gain energy when you turn

on a dead run
no jibing or tacking
just an absolute dead run
you will not exceed fttw speeds
asking the guy who doesnt think it can happen to dream up some formula to say it can happen is kinda fundamentally the wrong question
now I can form a summation as to why it wont happen
as I said

seems to me to obey all the basics and still keep it simple
add what ever calculations you want for A,B and F
but thats how they would stack up

seems like basic algebra to me

what I would love to see worked out is a dynamic analysis of energy distribution in a series of tacks running as close downwind as possible, including centripetal forces

but again
its not my burden of proof
whats beer cost in Finland these days
( course I dated a Fin once, girl could drink most of us under the table, so I might be getting myself in a little bit of trouble here )

Rick are you buyin
send me the actual diagram you want worked out and Ill give it a go
what the hell
is it going to be the one with the moving plate with the geared wheeled thing between them
cause Im thinkin
three beers for that one
( happy hour at the appaloosa $2.50 American bar tenders name is Jamie )
( Denver Pale Ail please )


peace people
sailing is just all in good fun
B

 

And now, presented for your approval:

http://www.youtube.com/watch?v=7xL8gRJ5F6k

in which it is shown that an electric treadmill can power a bitty propeller-driven cart in no wind at all!

I'm not sure what this is supposed to have to do with going DDWFTTW . . .

 

Curtis
The Youtube video is the same ones I linked earlier. This is simply a reversed frame of reference. The ground is moving and it is using force generated by the prop to move up hill. The fact that it moves uphill shows it is capable of extracting energy from the wheels to generate more thrust from the air than the drag on the wheels.

Back to the analysis so you gain insight--

Just in case you have not understood the problem I posed I will attach the two question sheets again here.

Once you provide the correct answers I will add a little more complexity that includes accounting for the forces and system losses.

The aim of this 5th grade exercise is to see if you can comprehend simple gearing. The understanding gets very simple after that. This is the most challenging aspect of the propeller/turbine system.

The offer of rep points is open to anyone who cares to provide the right answer showing their workings. Only the first right answer will get rep points from me.

Rick W.

 

#1 is .67m/s to the right
#2 is 6m/s to the right

front of the class or the dunce cap?


Edit----- assuming belts as pictured... gears will of course reverse the direction of movement.

 

I think I already saw that one
but having watched it again I am only further convinced that the system only seeks equilibrium with itself at some level bellow 100% efficient
when he first places the device on the tread mill
and there is nothing to say that tread mill is dead level which they never are
nor is the floor its placed on
the experimenter removes his hand in a forward direction imparting energy to the device and it briefly moves forward
he then pushes the device back which again imparts energy to the device
and it again briefly moves forward
which makes all the sense in the world if the mill has a slight incline forward

he does this a bunch for a while and imparting a additional energy to the device ( in the form of rotational force in the propeller )
which responds by failing to find equilibrium
once the system stabilizes and the experimenter leaves it alone for a while
it just sits there and without closer scrutiny there is no way to see if its not moving or if it is, in what direction
although they did get dam close to 100% efficiency
whatever its doing its not building steady velocity forwards
which is what would happen if it had even 101% efficiency

if the system were more than 100% efficient then the energy potential would be measured at per second/per second and build on itself indefinitely
that thing would rocket off the mill in a heartbeat

what I did notice was that as the thing began to set up a side to side motion when left alone for a few seconds
and that for some reason the experimenter looped the device around the tread mill early on in the flicker
doesn't bode well for them not being some jokers just pulling your leg
always something to consider when viewing unaccredited or verified research

my thinkin looking at the thing is given the number of connection points
and not knowing if they used magnetic bearings or not
ild say the have to have at lease a 1.5 to 3% friction loss <--(wild guess )
and with out actual data
thats going to be hard to see in the two or three seconds they showed the thing running on its own

that's why in order to really analyze this thing there needs to be real empirical data
and there isnt
could be for a reason
the numbers will always add up to less than 100% return of energy

my two cents
which you folks are bound to be getting sick on by now
so other than maybe run that system 66
Ill probably bow out shortly and leave you guys to your fun
B

 

Appaloosa Grill, 535 16th St. Denver • 720-932-1700
owners name is John
just tell em Ill be in tomorrow happy hour
almost seems unfair to get three beers for that
Denver Pale Ail
in case you forgot

soooo
why dont you now work out the energy in foot pounds of the system if the
sliding plate weighs two pounds and the roller device weighs four
given the plate is moving at twenty miles an hour

I think you are in france so that out to keep you busy for a few
Ill knock off one beer if you come up with the right answer
oh
then tell me how much force is required by the system to illicit that twenty miles an hour given there are four wheels each with a 1.5% friction loss and two pullies each with a 1% friction loss

at which point you may get a better understanding as to what Im trying to point out here

best B