The Wind Powered Sail-less Boat

<<<<or at any other angle, where i think is where it gets interesting and so far no one has gone into that.>>>>

Eventually i' ll get someone to consider what happens when

cos(beta) + (W/V)cos(alpha - beta) = 1

I hope..

 

This is quite easy, if you don't think about gear ratios. Just set the forces of wheels/turbine and propeller to be equal

Power at wheels/turbine

Pt = F * V

Power at turbine

Pp = F * (V-W) = Pt *e = F * V *e

=> V-W = V*e

=> W = (1-e) * V

=> V/W = 1/(1-e)

Thus with 2/3 overall efficiency and zero extra drag you get V =3 * W DDW. With zero efficiency you get V=W and with 1.0 efficiency you get infiniity.

Upwind the sign of W AND prop/turbine are reversed, thus you get

V/W = e/(1-e)

With 2/3 overall efficiency and zero extra drag you get V=2*W upwind.

Joakim

 

Tcubed:
>or at any other angle

Only speaking for our device, it becomes less efficient at any angle off the wind, up or down. This is because you can no longer optimize sail angle for the differing apparent wind each of the sails now sees on it's path.

There are several ways to deal with this -- cyclic pitch rotor head, pivoting rotor head, etc. but we're rather single minded ... we're truly only interested in the one trick pony -- DDWFTTW.

JB

 

Thanks Joakim.

Now maybe you can help me find the general solution to the problem, of which straight downwind (alpha = 180) , and straight upwind (alpha = 0) are just two special cases.

If beta is the angle between the apparent wind and the direction of motion of the machine and alpha is the angle between the true wind and the direction of motion;

i get

G = cos(beta) + (W/V)cos(alpha - beta)

I also get beta = arctan{(Wsin(alpha))/(V+Wcos(alpha))}

so we have a relation between V/W , G and alpha.

This can be graphed.

However, things get interesting along the locus of G = 1 which seems possible for the wheel model as long as alpha is not 0 or 180, but i don't think is possible with actual turbines/ props.

 

What are you actually looking for? Things get much more complicated at other angles, since you have side forces as well. You can not just use the longitudial component.

Joakim

 

I' m looking for the general solution for the wheeled model at all angles ignoring any moments. We already did this for straight upwind/downwind, i think there is no problem expanding the equations for all angles whilst carrying on ignoring heeling and pitching moments.

I' ve posted above what i got so far , please check if you want.

Really my concern is how does the situation G = 1 relate to a real turbine boat.

 

as I very clearly said immediately after you asked

I gotta say the hole thing makes me wonder how I got elected to be the guy you explain it to
hell Ive already shot this down in very short order with little more than a basic conservation of energy proof
you can explain it to whoever is reading
I just drop in for the entertainment from time to time

again what I may or may not believe is irrelevant to your ability to provide the mathematical analysis you offered

you did chime in with the following didnt you

all I said was go for it
so
go for it
were is your analysis that makes DDWFTTW work

Feel free to start from the beginning which to my mind is a detailed blueprint of what you propose along with the formula's for explaining energy transfer throughout.
IE
a detailed analysis
along with various proofs that show consistency with known physics

feel free to use any level of physics at your disposal and Ill be happy to look it over

dont feel like you have to convince *me*
the strength of your analysis is all the convincing you need to do

feel free to read post #169 for a basic explanation as to why the cart thing was nothing more than a good joke on a few gullible readers
oh and ya I goofed up when I wrote the formula for Newtons but hey when I was in school we used A.S. so sometimes I mix the symbols up
it shoulda read N=KG(M)/s2
my bad, I dont really bother looking to much stuff up unless Im actually doing a calculation

 

ThinAirDesigns, the link in post #283 - - http://www.mediafire.com/imageview.p...t2m3gz&thumb=5 gives me "error 404 file or directory not found" ????

 

Not sure what happened there masalai -- try this one:

http://www.mediafire.com/imageview.php?quickkey=ndqeit2m3gz&thumb=5

JB

 

I do apologize, as I did miss that answer. Thank you.

You probably shouldn't wonder any more as it look like perhaps you were "elected" by your vote of one -- it seems like you are the only one here espousing that "conservation of energy proof" @#169 as well ... proof.

I must say that it's a bit odd for someone who agrees that a device exists which can go *faster than the wind, powered only by the wind, steady state* to then argue that they have shot down a device that does it in the exact same manner based on a "conservation of energy proof".

Clearly, based on your ice-boat stipulation there is no "conservation of energy" issue with a sail on a broad reach powering a DWFTTW device.

Since both the stipulated ice-boat and the cart use a sail combined with a keel constraint to achieve VMG's greater than 1.0, your "proof" invalidates your stipulation. I'm now baffled as to your conflicting position.

JB

 

Mine must not be operating properly then because it DOES go directly downwind faster than the wind every time.

As a good friend said: "sure it works in practice - but can you prove it works in theory?"

I know the feeling exactly.

Does physical proof count? Mathematical proof appears to be quite prone to errors.

Here are a few places:


http://www.kiteforum.com/viewtopic.php?t=2328807

http://www.kiteforum.com/viewtopic.php?f=1&t=2329828&st=0&sk=t&sd=a

http://www.hanggliding.org/viewtopi...&start=0&sid=b481fb9032390532ad808cbf858dc29c

http://www.hanggliding.org/viewtopic.php?t=9340&postdays=0&postorder=asc&start=0

http://forums.sailinganarchy.com/index.php?showtopic=82175

http://forums.sailinganarchy.com/index.php?showtopic=31824&hl=dwfttw

http://community.discovery.com/eve/forums/a/tpc/f/7501919888/m/5081905889/p/1

http://community.discovery.com/eve/forums/a/tpc/f/9701967776/m/4561931559/p/1

http://forum.mythbustersfanclub.com/index.php/topic,12948.0.html

http://forum.mythbustersfanclub.com/index.php/topic,13182.msg141406.html#msg141406

http://www.runryder.com/helicopter/t242991p1/

http://www.helifreak.com/showthread.php?t=24303

http://ozreport.com/forum/viewtopic.php?t=6546&postdays=0&postorder=asc&start=0

http://forums.randi.org/showthread.php?t=128483

http://forums.randi.org/showthread.php?t=130705

http://scienceblogs.com/goodmath/2008/12/windpowered_perpetual_motion.php

http://scienceblogs.com/goodmath/2008/12/the_real_bozo_attempts_to_aton.php

http://www.quicktopic.com/38/H/H5gtdiufQT3nN

http://www.boingboing.net/2008/12/01/downwind-faster-than.html

http://www.boingboing.net/2008/12/03/directly-downwind-fa.html

http://www.boingboing.net/2008/12/12/downwind-faster-than-1.html

http://forums.makezine.com/comments.php?DiscussionID=2317&page=1&amp;page=1

http://www.physicsforums.com/showthread.php?p=1970193&posted=1#post1970193

http://www.physicsforums.com/showthread.php?t=274996

http://blog.dotphys.net/2008/12/physics-and-directly-downwind-faster-than-the-wind-dwfttw-vehicles/

http://monkeyfilter.com/link.php/16446

http://wordmunger.com/?p=997

http://blogs.scienceforums.net/swansont/archives/1075

http://www.abovetopsecret.com/forum/viewthread.php?tid=413138&page=2#pid5459835

http://forums.xkcd.com/viewtopic.php?f=18&t=31905&p=1194449#p1194449

 

several things

sailboats travel at an angle to the wind thus redirecting force while maximizing the variation in relative velocities between the bodies involved
and preserving apparent wind

ice boats do the same
run about 45 degs off wind
definitely not straight down wind

there is a ton of physics as to why you can loop a kite in a sign wave and gain additional velocity while standing in the middle of the pattern
Im really convinced you guys wouldn't understand it

the previous real cart model fails in every way specified
and was one piss poor example those guys got stuck on
so I rode it till it seemed good and dead
I notice not one other forum but maybe one even pretended to use bad/math
good/math

then I started offering beers to any one who could punch a hole in my analysis
not one taker

no at first I didnt believe in it
but the more I read and the more I learned about the inventor the greater respect I gained
guy was an aerospace engineer with McDonald-Douglass or close enough
bound to know his subject better than I do
but I prefer to remain skeptical as I will explain in detail
when in doubt err on the side of caution

no one specially Rick; who seemed pretty pissed off, could explain how the conservation of energy applied to the analysis of an ideal machine
it doesnt
ideal machines are models only
they are not considered to have mass friction or energy restrictions
real machines on the other hand do ( a point you also missed JB )
Kicked all your asses
huaaaa

my fave is that they were real quick to get stuck on there cart model and clearly were staying clear of what was designed by a aerospace engineer to be a brain teaser for aerospace engineers
no one including you JB knew how to even touch the DDWFTTW analysis

I saw that thing and went to town
studied the **** out of it
read all the physics sites
and laughed my *** off at you guys completely unable to explain it
you didnt invent it
you dont really know how it works
and your prevaricating rather than just admit it
you dont know the math

I got a paper with most of the numbers at
http://www.ayrs.org/DWFTTW_from_Catalyst_N23_Jan_2006.pdf

it was invented by I guy named Bouer or something like that
he was a aerospace engineer modeler in the days before they had auto cad
this thing has been around for about fifty or so years
its old hat kids

my fave is by failing to provide the detailed analysis offered, but instead stalling till help arrived, you prove you cant
oh Im sure you can mime what turns what, and how fast but if you want to show anyone you know whats up
this should be an easy one if you want to give it a try

explain the oscillation problem Bouer was working on

you said you could give any level of complexity required and guess what
you cant
if you could you would have a nonlinear analysis of the oscillation problem already worked out so you didnt bump into it for the show

finally after how many pages you busted out your patented list of sites that frankly, you get drilled on
dam I would think you guys would learn how to talk some physics rather than take all that abuse
every name in the book
why dont people spend just one day looking **** up
all I did was challenge you to show your work
you never did
so I guess you cant explain the toys you play with
but some of those folks were viciously insulting

I read nearly all that **** round about page six or so
oh
it looks like it only oscillates in the dynamic land model and will not consistently go faster than wind speed
or at least its never been proven to in a land test as far as I could find
and the problem is mentioned in several places

thats what all the extra wheels are for in Andy's picture
( the inventor )
old Andy was trying to get it to a steady state the hole way
not sure he ever did
not even his coauthor really made that clear
hell he stated real clearly he had trouble with the land tests
and thus began the debate
I think that original article in modelers magazine 91 is six bucks on eBay
if I were you guys Ild be snatching up a copy
the only steady force they got as near as I can crunch the numbers was when they did the treadmill test and that was likely because of the direction of mechanical advantage

hole thing is a balance of frictions trick

you guys are producers
and this is the level of homework you get past with
if you want to convince people of something
try going in with an overwhelming argument instead of sounding like you have no clue

this is wrong
tangential to the wind is a far cry from dead down wind
as the apparent wind is kinda helping out a little

conservation of energy works well in this case based on the mass and speed of the device the frictions involved and the mass and speed of the wind vs lift drag of the prop

thing to remember
its not I who cant explain his own toys

love B

 

And the thing you apparently won't slow down enough to grasp is that the sail on the cart does *THE EXACT SAME THING* ... they (there's two after all) "travel at an angle to the wind thus redirecting force while maximizing the variation in relative velocities between the bodies involved and preserving apparent wind"

The tip of the cart sail takes the same angled spiral/corkscrew path through the air that a ice-boat sail takes, generating the same thrusts from the same apparent wind, obeying all the same laws of physics.

You say an ice-boat can. You say the cart can't. Both sails generate thrust the same exact way following the same exact rules. You need to sort your contradiction out.

You are either:

A: being contradictory on purpose (least likely IMO)
B: focusing on the chassis of the cart and failing to trace the path of the sails(most likely IMO).

If the cart sails ARE taking the same angled spiral/corkscrew path through air that an ice-boat takes, how can you deny the propulsion? If you believe they are not, then say so and we'll easily demonstrate that they are.

JB

 

Im surprised after all the abuse from all the other sites you guys stick with the colloquial approach
a simple friction analysis of the system would be all the proof you need to show the interaction of the wheels prop and wind
but you refuse to present it
remember that hole thing about 2+2=4 well this is were it would come in handy
if you are unable to discuss the math then a simpler approach to the dynamics of the system might be to realize that its easier for the thing to spin the prop than not in a tail wind up to a point
that moment being the key sticking point were the pedestrian approach breaks down
where as if you had a mathematical analysis available to you you might be able to comprehend the troubles you are likely to run into with the floor model
I may be the lone soldier round here but I sure notice a mojority of detractors on the physics sites
the hole thing has a ring of undergraduate gimmicks taken from a nearly twenty year old magazine
specially what with how badly you guys defend it

its really a bad analogy to use the off wind trajectory of the ice yacht’s static vertical wing with the wind moving and the dead down hill run of the dynamic curricular prop in no apparent wind
the yacht never attempts to travel directly down wind instead works at an angle to it
the model must move directly down wind to pass the test
the yacht dynamics are based on there always being an apparent wind forcing its way past the craft
the models prop must force itself through zero apparent wind
plus all the various resistances of the system on a dead down wind run
with out the proper mathematical analysis and without the proper laboratory recreatable tests your not doing much better than the guy who invented this thing
and he had a mathematical analysis and he was an aerospace engineer
you guys decidedly are not
as far as I can tell he didnt prove it one way or the other
and neither have you

 

once again you guys are flailing
its not my baby to explain

balls always been in your court
still is
will be when the camera's roll

remember
there is an oscillation problem
whether you figure it out for all to see now
or for all to see later
its still going to be staring you in the face eventually

love B

ps
spork
way to show yourself completely unable to address the issues presented
my guess is you dont even remotely understand the nonlinear analysis