Re: DDW Faster than the wind
JohnF
> It's been proved possible by DOING IT.
>
> http://www.wired.com/autopia/2010/07/its-settled-downwind-faster-than-the-wind-officially-possible/
I don't think they've done it at all, but if they have
done something then I'd bet it was only momentarily
and not for any sustained time after the vehicle reaches
equilibrium with all forces acting on it. (see below for
how that could work)
One easy way to disprove the underlying idea is a simple change
of reference frame. The situation as seen by a stationary
observer (i.e., standing on the ground) would be
|
| wind speed
| -----------> w
|
| vehicle speed v > w
| --------------------> v
|
--+---------------------------------
|
But now imagine the same physical situation as
viewed by an observer running along at speed w,
so he feels no wind but still sees a moving vehicle
runner's reference frame speed
-----------> w
|
| runner's observed wind speed = 0
|
| observed vehicle speed
| ---------> v-w
|
--+---------------------------------
|
This situation, arrived at by a simple change of
reference frame, must be equally physically valid
as the same situation in the original frame.
But now we have the vehicle moving forward at
speed v-w without any wind whatsoever.
That's clearly "something for nothing" and
clearly physically impossible.
But like I suggested originally, you could look
like you're violating conservation of energy
momentarily. The web link doesn't describe the
prop/wheel coupling in detail, but here's one way
the "momentary violation" could work:
Suppose you add a ratcheted wind-up "mainspring"
between the wheel and prop. While the wind is still
pushing the vehicle forward (while v < w), it can be
used to wind up that spring. The vehicle will accelerate
slower, but will still eventually reach the wind
speed v = w, and also wind up the spring.
Then, as soon as v = w, you release the ratchet and
let the spring unwind, thus turning the prop and wheel,
and getting the vehicle to move still faster. But as
soon as the spring unwinds, that extra power is gone
and the vehicle slows back down to v = w.
--
John Forkosh ( mailto: j...@f.com where j=john and f=forkosh )
Wilbur Hubbard
news:dqs256105oabs5j8v...@4ax.com...
> It's been proved possible by DOING IT.
>
> http://www.wired.com/autopia/2010/07/its-settled-downwind-faster-than-the-wind-officially-possible/
Another big pile of rubbish - heaped up for imbeciles who think the laws of
physics can be broken.
Wilbur Hubbard
knuttle
> rom the guy whose existence proves that evolution doesn't always
> work.
>
We currently have a perpetual wind machine in the White House, why can
not they use the same perpetual motions machine to power a car.
It is logically impossible, as at over two times the speed of the wind
the car is making its own wind, there for it is creating energy. You
can not create energy from nothing.
Bruce in Bangkok
Since the feat was actually accomplished - not simply talked about -
what causes you to think that the laws of physics were broken?
Or is broken then what makes you believe that they were valid in the
first place?
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
Wayne.B
<brucein...@invalid.com> wrote:
>Since the feat was actually accomplished - not simply talked about -
>what causes you to think that the laws of physics were broken?
>
>Or is broken then what makes you believe that they were valid in the
>first place?
The laws of physics (and common sense) say that you can not accelerate
through AWS = 0 without some sort of stored energy system or a change
in wind speed/direction.
cavelamb
I'd need to know a whole lot more about this before I'll bite...
--
Richard Lamb
Bruce in Bangkok
How then did the set a new record? Or is the whole thing a hoax?
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
ThinAirDesigns
vehicle(s) in question.
Basics:
-- the spinning rotor is a propeller, not a turbine
-- the wheels provide the torque to turn the rotor (always).
-- the rotor does not provide the torque to turn the wheels (ever).
-- it will take off from a standing start on it's own.
-- we sometimes push it up to speed to save time during testing
-- there's no "null point' at windspeed.
-- It will maintain it's speed at or well above wind speed
indefinitely
-- There is no stored energy used to accelerate the vehicle at any
time
-- By design, our particular one works best when aimed directly
downwind.
-- One can be built to go faster than the wind in any direction
-- A simple gearing change will cause ours to go upwind rather than
down
Our project (www.FasterThanTheWind.org) was sponsored by Joby Energy
(wind energy research firm) and Google and associated with the
Aerospace Engineering department of San Jose State University here in
the Silicon Valley.
Our vehicles capabilities have now been verified (they installed 18
recording sensors) and a record ratified by NALSA (www.nalsa.org) at
2.8x the speed of the wind while traveling directly downwind.
There is absolutely no violation of the laws of nature going on here
-- and yes, I'm quite happy to provide equations to support the
physical evidence.
JB
Mark Borgerson
waynebatr...@hotmail.com says...
case, the vehicle has the kinetic energy it accumulated and stored when
AWS was not zero. There was also a lot of energy stored in the
rotational energy of the propellor.
Mark Borgerson
ThinAirDesigns
> case, the vehicle has the kinetic energy it accumulated and stored when
> AWS was not zero. There was also a lot of energy stored in the
> rotational energy of the propellor.
>
> Mark Borgerson
Hi Mark, our vehicle has a fixed ratio transmission between the the
props shaft and the wheel shaft (it's merely two sprockets and a
chain). This setup precludes using any stored energy from the
spinning propeller or other rotating drivetrain components to
accelerate the vehicle.
To remove energy from a spinning flywheel one much slow the flywheel
down. To remove energy from the spinning propeller, one must also
slow it down. Since the prop is directly geared to the wheels, if the
prop slows, so do the wheels and thus the entire vehicle.
Watch these two videos and we can see that the prop continued to
rotate faster as the vehicle accelerates through and above
windspeed.
http://www.youtube.com/watch?v=EEuAqq8FINw
http://www.youtube.com/watch?v=5CcgmpBGSCI
No stored energy is used to accelerate the vehicle at any time -- it's
not capable of it. Only the power of the wind.
JB
Wilbur Hubbard
news:dfb55607-4915-4388...@t5g2000prd.googlegroups.com...
http://www.youtube.com/watch?v=EEuAqq8FINw
http://www.youtube.com/watch?v=5CcgmpBGSCI
JB
==================[REPLY]=======================
Hogwash! Another big lie. It takes a fool to believe in any perpetual motion
machine and that is what you claim you have. Your claim involves the
following:
There is no wind - not one iota of wind. You get somebody to push the
machine up to a couple miles of hour and that gives you an apparent wind
from directly ahead of a couple mph. Then you claim you can somehow multiply
this wind to accelerate faster and faster. C'mon. Some people might be that
gullible but not we sane folks.
Wilbur Hubbard
ThinAirDesigns
> machine and that is what you claim you have. Your claim involves the
> following:
>
> There is no wind - not one iota of wind. You get somebody to push the
> machine up to a couple miles of hour and that gives you an apparent wind
> from directly ahead of a couple mph. Then you claim you can somehow multiply
> this wind to accelerate faster and faster. C'mon. Some people might be that
> gullible but not we sane folks.
>
> Wilbur Hubbard
No, that is YOUR claim -- not our claim.
Wilbur -- is it your opinion that NALSA (http://www.nalsa.org), the
organization with more experience measuring wind powered land speed
vehicles than anyone in the world was not able to determine whether
the vehicle was a hoax or not when they had it IN THEIR POSSESSION and
assembled and disassembled it looking for any hidden sources of
energy? That organization placed 18 recording sensors on the vehicle
and course and after reviewing their data ratified a record of the
vehicle going directly downwind nearly 3 times the speed of the wind.
Is it your opinion that one of the foremost aerodynamic authorities in
the world (Dr. Mark Drela, MIT professor and aero legend) is wrong in
his analysis where he demonstrates mathmatically and claims that what
we did with our vehicle is actually rather easy to do?
Thanks
JB
George Orwell
The real world is where scumwads like Cecil rape women.
He learned how to be fag in prison, and now he's just limp.
Poor wittle Gweggie... are you gay? Is that your problem? Did your butt-buddy in prison turn you?
Who's your prison boyfriend? Did he suck you off? I don't see how that would help, since you can't get it up any more.
Marathon, Florida IP address:
66.176.108.112
Gregory Hall AKA Neal Warren AKA Wilbur Hubbard IS A RAPIST
Designation: Sexual Offender
Name: CECIL WARREN
Status: Released - Required to Register
Department of Corrections #: Not Available
Date of Birth: 03/24/1943
Race : White
Sex: Male
Hair: Brown
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Weight: 147 lbs
Binghamton, NY 13905-1829
Broome COUNTY
More details at: http://offender.fdle.state.fl.us:80/offender/flyer.do?personId=35467
Il mittente di questo messaggio|The sender address of this
non corrisponde ad un utente |message is not related to a real
reale ma all'indirizzo fittizio|person but to a fake address of an
di un sistema anonimizzatore |anonymous system
Per maggiori informazioni |For more info
https://www.mixmaster.it
JohnF
JB,
Please follow up with those equations. And, if it's public
domain info, with the detailed design of that vehicle.
And care to share your full name?
Meanwhile, you didn't address my earlier argument.
And just for kicks here's another one...
At some point the vehicle reaches the wind speed.
At that point there are no external forces (besides air resistance
and rolling friction from the wheels, which would both slow the
vehicle down) acting on it whatsoever.
And you yourself say above:
-- There is no stored energy used to accelerate the vehicle
at any time
Therefore there are no "internal" forces acting on the vehicle
either. Thus, the total net forces acting on the vehicle are zero.
So exactly how does it accelerate past this point???
I'll bet you (anybody reading this) JB can't answer either
of my two arguments. Go ahead, JB, I dare you!!!
Also note JB's claim that
-- A simple gearing change will cause ours to go upwind
rather than down
Yeah, right. You hopefully realize sailing, on water or land,
directly upwind is impossible -- even in some propeller-driven
vessel (i.e., it's fundamentally physically impossible, not just
because sails get stuck in irons).
And I'd bet JB's claimed association with San Jose State
University is totally bogus. Indeed, why not forward JB's
posted claim to http://www.sjsu.edu/ and see how they feel
about it?
Somehow, I assume there's a fraudulent money-making scam
involved, and that JB would be delighted to accept your
investment in this bogus technology.
cavelamb
ThinAirDesigns
> Please follow up with those equations.
Be happy to. Here are two comprensive analysis done by MIT professor
and aero legend Dr. Mark Drela (google him).
http://www.boatdesign.net/forums/attachments/propulsion/28167d1231128492-ddwfttw-directly-downwind-faster-than-wind-ddw2.pdf
http://www.boatdesign.net/forums/attachments/propulsion/28168d1231128492-ddwfttw-directly-downwind-faster-than-wind-ddwe.pdf
His MIT email is very public if you doubt him as author.
>>And, if it's public domain info, with the detailed design of that vehicle.
It's extremely public -- the entire construction was documented at our
project site: http://www.fasterthanthewind.org
> And care to share your full name?
Not a problem -- it's John Borton. Here is my bio from the project
blog: http://www.fasterthanthewind.org/2009/10/john-borton-jb.html
> And I'd bet JB's claimed association with San Jose State
> University is totally bogus. Indeed, why not forward JB's
> posted claim tohttp://www.sjsu.edu/and see how they feel
> about it?
You really are going to want to stop betting about such things 'cause
it's not going to go well for you. Here is the SJSU professor's bio
from our project blog. Feel free to send Dr. Mourtos an email.
http://www.fasterthanthewind.org/2009/10/professor-aerospace-engineering.html
JB
ThinAirDesigns
> Is this record for peak speed, or sustained?
NALSA (http://www.nalsa.org) recorded our peak to be over 3.7x the
speed of the wind. The number that was ratified for 'steady state'
was 2.8x.
JB
Wayne.B
<wilbur...@thefarm.invallid> wrote:
>There is no wind - not one iota of wind. You get somebody to push the
>machine up to a couple miles of hour and that gives you an apparent wind
>from directly ahead of a couple mph. Then you claim you can somehow multiply
>this wind to accelerate faster and faster.
That's not the way it works. I was under the same misunderstanding
that AWS was required to turn the prop. Instead the wheels turn the
prop and the prop provides thrust. As a result the prop is still
providing thrust at AWS = 0, and if drag is low enough, that thrust is
enough to continue accelerating the vehicle until thrust = drag.
John Forkosh
>> JB,
>> ? ?Please follow up with those equations. ?
>
> Be happy to. Here are two comprensive analysis done by MIT professor
> and aero legend Dr. Mark Drela (google him).
>
> http://www.boatdesign.net/forums/attachments/propulsion/28167d1231128492-ddwfttw-directly-downwind-faster-than-wind-ddw2.pdf
> http://www.boatdesign.net/forums/attachments/propulsion/28168d1231128492-ddwfttw-directly-downwind-faster-than-wind-ddwe.pdf
>
> His MIT email is very public if you doubt him as author.
Okay, thanks, I already did. Didn't count on that, did ya???
Here's the text -- and I apologize in advance about the "JB" parts
of it; I didn't have your name when I wrote it. And, I kind of
suspected (incorrectly, as it turns out) that I never would.
Anyway, here's that email. Let's just see what happens...
------------------------ start of email -------------------------------
Date: Sat, 31 Jul 2010 15:08:26 -0400 (EDT)
From: John Forkosh
To: Prof. Mark Drela <dr...@mit.edu>
Subject: Downwind faster than the wind
Dear Professor Drela,
Please forgive the interruption. I'm writing you regarding
http://www.wired.com/autopia/2010/07/
its-settled-downwind-faster-than-the-wind-officially-possible/
and what's being promoted as your analysis justifying it at
http://www.boatdesign.net/forums/attachments/propulsion/
28167d1231128492-ddwfttw-directly-downwind-faster-than-wind-ddw2.pdf
These are being discussed in the usenet newsgroup rec.boats.cruising
in the thread "DDW faster than the wind". In particular, someone
calling himself only JB (email: ThinAir...@aol.com) says he's
"one of the two primary designers/builders of the vehicle(s)"
described at
http://www.thinairdesigns.com/
http://www.fasterthanthewind.org/
and that both you and San Jose State University (http://www.sjsu.edu)
are affiliated with JB's project.
I suggested the following two simple canonical arguments why "downwind
faster than the wind" isn't physically possible. (These arguments are
for the land vehicle, though it's trivial to also account for current
when discussing a water-based vessel.) Is there some flaw in either
argument? If not, how can such a vehicle work regardless of its
engineering design?
First Argument: change of reference frame...
One easy way to disprove the underlying "dwonwind faster
than the wind" idea is a simple change of reference frame.
The situation as seen by a stationary observer (i.e., standing
on the ground) would be
|
| wind speed
| -----------> w
|
| vehicle speed v > w
| --------------------> v
|
--+---------------------------------
|
Now imagine the same physical situation, but as
viewed by an observer running along at speed w,
so he feels no wind but still sees a moving vehicle
runner's inertial reference frame speed
-----------> w
|
| runner's observed wind speed = 0
|
| observed vehicle speed
| ---------> v-w
|
--+---------------------------------
|
This situation, arrived at by a simple change of
reference frame, must be equally physically valid
as the same situation in the original frame.
But now we have the vehicle moving forward at
speed v-w without benefit of any wind whatsoever.
That's clearly getting "something for nothing"
(violating conservation) and clearly not physically
possible.
Second Argument: net forces...
At some point after starting from rest the vehicle reaches
the wind speed. At that point there are no external forces
(besides air resistance and rolling friction from the wheels,
which both just slow the vehicle down) acting on it whatsoever.
And JB says in the rec.boats.cruising thread:
-- There is no stored energy used to accelerate the vehicle
at any time
Therefore there are no "internal" forces acting on the vehicle
either. Thus, the total net forces acting on the vehicle are zero.
So exactly how can it accelerate past this point???
Regardless of these arguments, who exactly is this JB person?
His credentials and intentions (i.e., some kind of scam?) seem
dubious, at best, to me. But please read the thread for yourself
and draw your own conclusions. Do you want this semi-anonymous
JB person using your name to legitimize his project and promote
his business?
I've posted this email in that thread, and will follow that up
with your email reply if I have your permission to do so.
Thank you very much for your time, and, again,
please forgive the interruption,
John Forkosh
------------------------ end of email -------------------------------
>>>And, if it's public domain info, with the detailed design of that vehicle.
>
> It's extremely public -- the entire construction was documented at our
> project site: http://www.fasterthanthewind.org
>
>> And care to share your full name?
>
> Not a problem -- it's John Borton. Here is my bio from the project
> blog: http://www.fasterthanthewind.org/2009/10/john-borton-jb.html
>
>>? And I'd bet JB's claimed association with San Jose State
>> University is totally bogus. ?Indeed, why not forward JB's
>> posted claim tohttp://www.sjsu.edu/and see how they feel
>> about it?
>
> You really are going to want to stop betting about such things 'cause
> it's not going to go well for you. Here is the SJSU professor's bio
> from our project blog. Feel free to send Dr. Mourtos an email.
>
> http://www.fasterthanthewind.org/2009/10/professor-aerospace-engineering.html
Look, John, that's all very impressive, but you still haven't
accepted my "dare" to address the two fundamental physical arguments
I suggested, and that I repeated to Prof. Drela. So, like I said,
let's just wait and see what he says. Hey, all you regular
rec.boats.cruising posters: want to place your bets now? :)
This is all just freshman physics. It's >>trivially<< simple
and just not wrong. You're wrong; you know it; and your vehicle
never worked as advertised. I have no idea what's going on,
or what your game is. But it ain't "downwind faster than the wind."
And, hey, I'd >>love<< to be proved wrong -- energy crisis over.
Whatever you designed could easily be re-engineered to produce
excess energy outout for nothing input. I'd be delighted to be
embarrassed for that outcome. Unfortunately, we know that's not
what's gonna happen.
ThinAirDesigns
There's no 'counting on' or not 'counting on'. It's his analysis and
not mine so he can answer any questions regarding it that he feels
like.
I hope you also emailed Dr. Mourtos at SJSU so you can lose another
point of your 'bet".
JB
ThinAirDesigns
> In particular, someone
> calling himself only JB (email: ThinAirDesi...@aol.com) says he's
> "one of the two primary designers/builders of the vehicle(s)"
> described at
> http://www.thinairdesigns.com/
> http://www.fasterthanthewind.org/
> and that both you and San Jose State University (http://www.sjsu.edu)
> are affiliated with JB's project.
John, I just actually read your email to Dr. Drela and I see a very
LARGE mistake you made:
Would you mind showing me ANYWHERE that I claimed that Dr. Drela is
"affiliated" with our project?
I have clearly stated that Dr Mourtos is affiliated with our project
but I have NEVER said a single word that could be construed as such
regarding Dr. Drela.
I would appreciate it if you would either show me where I said any
such thing or make a correction to Dr Drela.
Thanks
JB
JohnF
>> Okay, thanks, I already did. ?Didn't count on that, did ya???
>
> There's no 'counting on' or not 'counting on'. It's his analysis and
> not mine so he can answer any questions regarding it that he feels
> like.
But, by your own words, you're "one of the two primary designers".
I expected that if you designed it then you'd understand how and
why it works, and could refute any freshman mechanics (literally)
objections. But, okay, it's punted to Drela.
> I hope you also emailed Dr. Mourtos at SJSU so you can lose another
> point of your 'bet".
Nope, but I will if Prof. Drela's reply leaves some doubt.
My only doubt is where that
http://www.wired.com/autopia/2010/07/
its-settled-downwind-faster-than-the-wind-officially-possible/
article came from. You're right that if all those people tested
and measured and calculated, then it can't be all wrong.
But it is all wrong. My only plausible guess is that you're
just telling us the "Big Lie", over and over and over again,
and that wired.com swallowed it without sufficient checking.
And it amazes me that many posters in this ng, with lots of
sailing sense if not much formal physics education, seem to be
swallowing it, too. (And I found myself shaking my head back
and forth in disbelief as I wrote that.) Congrats, John, at
constructing such a good con. How're you intending to monetize it?
JohnF
> John Forkosh:
>>?In particular, someone
>> calling himself only JB (email: ThinAirDesi...@aol.com) says he's
>> "one of the two primary designers/builders of the vehicle(s)"
>> described at
>> ? ?http://www.fasterthanthewind.org/
>> and that both you and San Jose State University (http://www.sjsu.edu)
>> are affiliated with JB's project.
>
> John, I just actually read your email to Dr. Drela and I see a very
> LARGE mistake you made:
>
> Would you mind showing me ANYWHERE that I claimed that Dr. Drela is
> "affiliated" with our project?
>
> I have clearly stated that Dr Mourtos is affiliated with our project
> but I have NEVER said a single word that could be construed as such
> regarding Dr. Drela.
>
> I would appreciate it if you would either show me where I said any
> such thing or make a correction to Dr Drela.
>
> Thanks
Is that right? Sorry. I accumulated the email's info (as you
can see by reading it) from several posts in this thread and from
various web pages they pointed to, apparently without scrupulous
enough quote checking.
I'm not going to re-email Drela right now, but will personally
correct it in any further email prompted by his reply. Meanwhile,
you can, of course, email him yourself, and cut-and-paste this post
as my apology.
Wilbur Hubbard
You didn't answer the question. You just loaded on a bigger pile of bullshit
on the hay wagon.
Answer the question. You claim to have a perpetual motion machine there.
Sorry, but there is no such thing. Can somebody push that thing up to five
miles per hour in no wind conditions and can it use the apparent wind coming
from directly ahead to continue to accelerate? If you claim so then you are
a liar.
If it were true you wouldn't be hoaxing people on Usenet. You would be a
multi-billionaire for solving the world's energy needs.
Wilbur Hubbard
Wilbur Hubbard
news:4au85650r78v07269...@4ax.com...
And there is zero friction in the entire system - no loss of energy
anywhere?
My, oh my. So a bicycle chain and sprockets is 100% efficient? <lol>
You are claiming to believe in a perpetual motion machine. You are one of
those fools born every minute.
Wilbur Hubbard
Wilbur Hubbard
JB
============================[REPLY]=====================
Then that PROVES it thing wasn't going directly downwind. If the wind was
10mph and your machine was going directly downwind then when it reached
10mph there would be NO APPARENT WIND OVER THE MACHINE. The wheels that
supposedly drive the propeller for forward motion would then loose any
ability to produce energy. The thing would slow down and stabilize somewhere
under 10mph. The deficit caused by friction.
You are a moron. You are claiming an infinite loop of energy that builds
upon itself. It can't happen in the real world.
If your machine went faster than the wind it DID NOT DO SO directly downwind
as the apparent wind is all that counts respecting the machine. The sad
thing about apparent wind is when you go directly downwind as fast as the
apparent wind then there IS NO WIND experienced by the machine. Get a clue.
You lose! Your hoax assumes people are too stupid to understand apparent
wind. What you claim as going directly downwind is a false claim.
Wilbur Hubbard
Wilbur Hubbard
news:i31lbn$ovt$1...@reader1.panix.com...
The only thing more pathetic than JB is all the physics illiterate morons
who are so willing to be duped by a fellow moron.
Wilbur Hubbard
Wilbur Hubbard
news:i31tvs$4vq$1...@reader1.panix.com...
That he putzing around on Usenet trying to sell a hoax which, if it was not
a hoax, would solve all the world's energy needs and result in an infinite
energy surplus causing him to be rich beyond belief and elevated to God
status should tell everybody that he's just another flim-flam man.
Wilbur Hubbard
ThinAirDesigns
> correct it in any further email prompted by his reply.
Thanks -- he will certainly be surprised to hear from your email that
he is "affiliated" with the project (as he is not nor has never been).
>But, by your own words, you're "one of the two primary designers".
>I expected that if you designed it then you'd understand how and
>why it works, and could refute any freshman mechanics (literally)
>objections. But, okay, it's punted to Drela.
I do and can, but many people for some reason seem to prefer the work
of an MIT aero professor of that of others.
JB
brian whatcott
> On 7/30/2010 4:23 PM, sa...@dog.com wrote:
>> rom the guy whose existence proves that evolution doesn't always
>> work.
>>
> We currently have a perpetual wind machine in the White House, why can
> not they use the same perpetual motions machine to power a car.
>
>
> It is logically impossible, as at over two times the speed of the wind
> the car is making its own wind, there for it is creating energy. You can
> not create energy from nothing.
Here's how this thing works:
The back wheels drive the vehicle.
No mystery there. That's how a good fraction of all cars work.
Now: where does the power come from?
From a propeller.
But the vehicle is moving faster than the wind.
Yes, but it's not the vehicle that's driving the wheels, it's the prop
that drives the wheels.
Now here's the hard to understand bit.
The prop is moving forwards through the airstream, that's a given.
So the prop has to take energy out of the air departing to the rear.
But that's what a wind turbine does - extract energy out of the
airstream - so you know it can happen. The flatter side of the blade
is on the forward side, and the curved surface is [effectively] down
wind, just like the wind-turbine. The energy transmitted to the wheels
has to overcome the air resistance of the vehicle and rider, for sure....
Brian W
brian whatcott
> On Sat, 31 Jul 2010 07:16:58 +0700, Bruce in Bangkok
> <brucein...@invalid.com> wrote:
>
>> Since the feat was actually accomplished - not simply talked about -
>> what causes you to think that the laws of physics were broken?
>>
>> Or is broken then what makes you believe that they were valid in the
>> first place?
>
> The laws of physics (and common sense) say that you can not accelerate
> through AWS = 0 without some sort of stored energy system or a change
> in wind speed/direction.
>
If you visualize the situation at the prop tips you will overcome this
idea...
Brian W
brian whatcott
>> ..not we sane folks.
>>
>> Wilbur Hubbard
>
> No, that is YOUR claim -- not our claim.
>
> Wilbur -- is it your opinion that NALSA (http://www.nalsa.org), the
> organization with more experience measuring wind powered land speed
> vehicles than anyone in the world was not able to determine whether
> the vehicle was a hoax or not when they had it IN THEIR POSSESSION and
> assembled and disassembled it looking for any hidden sources of
> energy? That organization placed 18 recording sensors on the vehicle
> and course and after reviewing their data ratified a record of the
> vehicle going directly downwind nearly 3 times the speed of the wind.
>
> Is it your opinion that one of the foremost aerodynamic authorities in
> the world (Dr. Mark Drela, MIT professor and aero legend) is wrong in
> his analysis where he demonstrates mathmatically and claims that what
> we did with our vehicle is actually rather easy to do?
>
> http://www.boatdesign.net/forums/attachments/propulsion/28167d1231128492-ddwfttw-directly-downwind-faster-than-wind-ddw2.pdf
>
> Thanks
> JB
>
Offering Mark Drela as support will not go very far with Wilbur I'm
afraid. Wilbur's engineering credentials include repairing a broken
boom with three iron pipes stuffed in it with goop.
Congratulations, by the way!
Brian W
brian whatcott
> Hi folks. I'm one of the two primary designers/builders of the
> vehicle(s) in question.
>
> Basics:
> -- the spinning rotor is a propeller, not a turbine
> -- the wheels provide the torque to turn the rotor (always).
Hehe...this will undoubtedly confound the innocent.
This propeller, this rotor: would you say its rather like the rotor of
a gyrocopter, being spun with the wind flowing down through the blades?
I guess you handle the fabrication end of things?
:-)
Brian W
cavelamb
I had considered part of that.
The propeller (once spun up) always sees higher than apparent wind speed.
But once the vehicle matches true wind speed, apparent wind would be zero.
WTF then?
Quickly accelerate the vehicle past that point and now the propeller sees wind
from the other direction.
That's ain't gonna work.
So, is the propeller facomg straight into the wind or not?
--
Richard Lamb
ThinAirDesigns
> afraid. Wilbur's engineering credentials include repairing a broken
> boom with three iron pipes stuffed in it with goop.
>
> Congratulations, by the way!
>
> Brian W
Yes, I clearly don't need to fiddle with Wilber - I'll leave him to
his ignorant bliss.
And thanks on the congrats.
JB
cavelamb
One should always check his prejudices before claiming thought...
A bicycle chain can be very efficient: one study reported efficiencies as high
as 98.6%.[1] The study, performed in a clean laboratory environment, found that
efficiency was not greatly affected by the state of lubrication.[1] A larger
sprocket will give a more efficient drive, reducing the movement angle of the
links. Higher chain tension was found to be more efficient: "This is actually
not in the direction you'd expect, based simply on friction".[1]
http://en.wikipedia.org/wiki/Bicycle_chain
--
Richard Lamb
ThinAirDesigns
> Here's how this thing works:
>
> The back wheels drive the vehicle.
> No mystery there. That's how a good fraction of all cars work.
Brian, I have to stop you right there -- the back wheels do NOT drive
the vehicle. The force acting on the back wheels is a braking force
-- a force attempting to slow the vehicle down, not a driving force.
Much of what you say after you said the above is also wrong because it
is based on the above.
The wheels drive the propeller -- the thrust of the propeller drives
the vehicle forwards. The spinning rotor NEVER drives the wheels.
JB
ThinAirDesigns
> This propeller, this rotor: would you say its rather like the rotor of
> a gyrocopter, being spun with the wind flowing down through the blades?
No. The rotor on a gyrocopter functions as a turbine only (well,
there are a *few* of the more expensive gyrocopters with powered
rotors, for short takoffs, but generally not). The blades on this
vehicle act always as propeller blades and never as turbine blades.
> I guess you handle the fabrication end of things?
There are two of us that handled most of the design and fabrication.
I was more responsible for the mechanical design while he bore more of
the aero load, but there was overlap.
JB
ThinAirDesigns
Currently you seem to be asking question that are based on some
misinformation that Brian W put out - so I'm not going to answer them.
I'm happy to answer questions from you, but I'll let you ask them of
me directly if you wish me to answer.
JB
Wayne.B
<ThinAir...@aol.com> wrote:
>I'm happy to answer questions from you, but I'll let you ask them of
>me directly if you wish me to answer.
What is the typical true wind speed (TWS) for your test runs?
What is the lowest TWS with which you can generate sustained motion
assuming a brief push start?
ThinAirDesigns
> What is the typical true wind speed (TWS) for your test runs?
We optimized the propeller for 18-20mph. We hoped to perhaps get as
high as 2x wind speed so we constructed a vehicle and drive train to
handle those loads and speeds (~40mph).
We were more successful than we expected (max of over 3.5x wind speed)
so we had to run in lower winds for the record than we had planned --
we just didn't want to run the vehicle at 60+mph (not safe for that).
> What is the lowest TWS with which you can generate sustained motion
> assuming a brief push start?
In winds of 7-8 mph we can still achieve greater than wind speed by a
bit. It takes about 10mph before the vehicle will self start.
JB
Bruce in Bangkok
The theory seems to be that by propelling the vehicle to a given speed
that the kinetic energy of the vehicle is sufficient to drive the
propeller to produce more thrust then required to propel the vehicle
at that speed. i.e.,
If the vehicle is propelled by an outside force to a speed of 1 MPH
the energy now stored in the forward motion of the vehicle is
sufficient to power the propeller to develop a thrust to produce 1+
MPH speed, which in turn develops more kinetic energy which drives the
vehicle to a faster speed, and on and on.....
Until you reach a speed where drag is equal to propeller effectiveness
- which is very fast indeed.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
ThinAirDesigns
> The theory seems to be that by propelling the vehicle to a given speed
> that the kinetic energy of the vehicle is sufficient to drive the
> propeller to produce more thrust then required to propel the vehicle
> at that speed. i.e.,
>
> If the vehicle is propelled by an outside force to a speed of 1 MPH
> the energy now stored in the forward motion of the vehicle is
> sufficient to power the propeller to develop a thrust to produce 1+
> MPH speed, which in turn develops more kinetic energy which drives the
> vehicle to a faster speed, and on and on.....
Sorry Bruce, that's not how it works. The kinetic energy of the
vehicle is not used in any way to accelerate the vehicle-- only the
energy removed from the wind.
JB
cavelamb
So answer.
Or buzz off.
You are definitely starting to sound like a troll...
--
Richard Lamb
ThinAirDesigns
> So answer.
> Or buzz off.
Did I miss a question you asked me somewhere?
JB
ThinAirDesigns
(initially assume lossless components -- we'll deal with the losses
near the bottom)
A:
1.0 HP = 550 foot-pounds per second
(http://en.wikipedia.org/wiki/Horsepower)
This means that @55ft/sec, 10lbs of forwards force will produce 1.0HP
at the wheels
B:
1/2HP = 275 foot-pounds per second
This means that at 27.5ft/sec, 10lbs of thrust can be produced with
1/2HP at the prop shaft
C:
If the wind is blowing at 27.5ft/sec (~20mph) and our vehicle is
traveling DDW at 2x the speed of the wind (~40mph), the vehicle is
traveling over the ground at 55ft/sec and through the air at only
27.5ft/sec.
D:
Through the establishment of "A", we know we can pull 1.0 HP from the
wheels of the vehicle propelled by 10lbs of force, and through the
establishement of "B" we can see that the propeller in the tailwind
only needs 1/2HP input to produce that same 10lbs of force.
E:
After using 1/2HP of the total 1HP available to propel the vehicle,
there is 1/2HP available to use up in losses (told you we would get
to
losses).
Do the same calcs on a no wind day and it's easy to see that the
wheels still produce 1.0HP at 55ft/sec, but now the propeller is
force
to do work at 55ft/sec rather than 27.5ft/sec and it now takes a full
1.0HP at the prop to produce the 10lbs of force. This of course means
that there is nothing left for losses and since there is *always*
losses, the vehicle simply can't motivate.
In the real world we don't have lossless components, but neither do
we
use a generator and motor as the transmission method (they are
relatively inefficient compared to a chain drive) If you consider an
85% efficient propeller (easy to achieve) and an 85% drive train
(even
easier to achieve) and we've still got nearly 1/4 HP left over for
the
Crr of the tires (very low for high pressure bike tires) and aero
drag.
There's no magic and no laws are violated. It's a simple but
unusually looking application of long established principles.
JB
brian whatcott
Whatever you say, JB :-)
B
brian whatcott
B
brian whatcott
> Energy/force balance:
>
> (initially assume lossless components -- we'll deal with the losses
> near the bottom)
>
> A:
> 1.0 HP = 550 foot-pounds per second
> (http://en.wikipedia.org/wiki/Horsepower)
>
> This means that @55ft/sec, 10lbs of forwards force will produce 1.0HP
> at the wheels
>
> B:
> 1/2HP = 275 foot-pounds per second
>
> This means that at 27.5ft/sec, 10lbs of thrust can be produced with
> 1/2HP at the prop shaft
>
> C:
> If the wind is blowing at 27.5ft/sec (~20mph) and our vehicle is
> traveling DDW at 2x the speed of the wind (~40mph), the vehicle is
> traveling over the ground at 55ft/sec and through the air at only
> 27.5ft/sec.
I.e. it sees a 20 mph headwind, right? :-)
>
> D:
> Through the establishment of "A", we know we can pull 1.0 HP from the
> wheels of the vehicle propelled by 10lbs of force, and through the
> establishement of "B" we can see that the propeller in the tailwind
> only needs 1/2HP input to produce that same 10lbs of force.
>
Did you mean to say a 20 MPH tailwind, or did you mean a 20 MPH
headwind? :-)
> E:
> After using 1/2HP of the total 1HP available to propel the vehicle,
> there is 1/2HP available to use up in losses (told you we would get
> to
> losses).
Uh? Who said there was 1 HP available to the vehicle?
> JB
>
I probably am missing something. how much thrust does your partner
think is available when traveling at 40 MPH in a 20 MPH following wind?
Regards
Brian W
cavelamb
Bruce in Bangkok
You have said that the propeller is driven by the wheels and that the
propeller is what is powering the vehicle. You have also said that you
sometimes pushed the vehicle to get it started. Now you say that only
the wind energy is accelerating the vehicle.
There is something wrong with your explanation.
If, as you say, only the energy removed form the wind moves the
vehicle then there is no requirement for the propeller, is there?
If, on the other hand, if the propeller is driven by the vehicle's
wheels than you are at least part of the time utilizing the energy
stored in the vehicle ( mass x Velocity2) to drive the propeller.
But in essence you are saying that the wind propels the vehicle at,
say 1 MPH, which turns the vehicle wheels, which drive the propeller
with enough energy that the propeller accelerates the vehicle to 1+
MPH.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
ThinAirDesigns
>and that the propeller is what is powering the vehicle.
The propeller is driven by the wheels, and the thrust of the propeller
pulls the vehicle forward -- the wind powers the entire process.
>You have also said that you sometimes
>pushed the vehicle to get it started.
>Now you say that only the wind energy is
>accelerating the vehicle.
That is correct -- it *can* start on it's own (http://www.youtube.com/
watch?v=5CcgmpBGSCI), but sometimes we push it to save the time it
takes to get that first few mph. We'll do this primarily when we are
testing in a short course -- if we push to few mph we can cut about a
half mile of the course we need to get up to speed. If the course it
long enough we'll generally do like we did in the above record video
and let it start on it's own.
NALSA rules allow only 'human on foot' push starting.
> There is something wrong with your explanation.
>
> If, as you say, only the energy removed form the wind moves the
> vehicle then there is no requirement for the propeller, is there?
There is certainly a requirement for the propeller if you want to go
DDWFTTW. Without the prop you would never even get to windspeed. The
prop is the device that allows you to remove energy from the wind
while at and above WS.
> If, on the other hand, if the propeller is driven by the vehicle's
> wheels than you are at least part of the time utilizing the energy
> stored in the vehicle ( mass x Velocity2) to drive the propeller.
If the wind lulls and we are *coasting*, then of course that is true.
That is why NALSA rules say that this stored energy can't be used to
*accelerate* the vehicle. This stored energy can't help you go
faster ... only coast further.
> But in essence you are saying that the wind propels the vehicle at,
> say 1 MPH, which turns the vehicle wheels, which drive the propeller
> with enough energy that the propeller accelerates the vehicle to 1+
> MPH.
During the start, that is in essence what happens (though it takes
more like 7-8mph before the propeller comes unstalled at all). Once
at or above WS, the chassis no longer providing any motivation from
the tailwind.
JB
ThinAirDesigns
Yes.
JB
Richard Casady
<bet...@sbcglobal.net> wrote:
>Now here's the hard to understand bit.
>The prop is moving forwards through the airstream, that's a given.
t
No it is not a given. Not even close. The air is blowing through the
prop from behind at all times.
>So the prop has to take energy out of the air departing to the rear.
It can't and doesn't.
Casady
Richard Casady
<bet...@sbcglobal.net> wrote:
>> The laws of physics (and common sense) say that you can not accelerate
>> through AWS = 0 without some sort of stored energy system or a change
>> in wind speed/direction.
>>
>
>If you visualize the situation at the prop tips you will overcome this
>idea...
If you visualize a puff of smoke floating downwind and then
accelerating in some direction, you have another ridiculous attempt to
imagine getting something for nothing.
Casady
ThinAirDesigns
> > C:
> > If the wind is blowing at 27.5ft/sec (~20mph) and our vehicle is
> > traveling DDW at 2x the speed of the wind (~40mph), the vehicle is
> > traveling over the ground at 55ft/sec and through the air at only
> > 27.5ft/sec.
Brian:
> I.e. it sees a 20 mph headwind, right? :-
Yes, in the above scenario, the vehicle moving forward through the air
at ~20mph giving it an apparent headwind.
Me:
> > D:
> > Through the establishment of "A", we know we can pull 1.0 HP from the
> > wheels of the vehicle propelled by 10lbs of force, and through the
> > establishement of "B" we can see that the propeller in the tailwind
> > only needs 1/2HP input to produce that same 10lbs of force.
Brian:
> Did you mean to say a 20 MPH tailwind, or did you mean a 20 MPH
> headwind? :-)
There is a true tailwind of 20mph and an apparent headwind of 20mph.
Without the tailwind, the apparrent headwind would be 40mph as that's
the speed the vehicle in question is traveling across the ground.
> Uh? Who said there was 1 HP available to the vehicle?
That is the first thing established in "A" (10lbs force at 55ft/sec =
1.0hp
> I probably am missing something.
The energy balance is a generic example using an even 1.0hp example
just so it's easy to work with. Our large vehicle involves much
higher numbers, though the calcs would work the same.
>how much thrust does your partner think is available when
>traveling at 40 MPH in a 20 MPH following wind?
At 2x we are producing about 60-70lbs thrust.
JB
ThinAirDesigns
>The air is blowing through the prop from behind at all times.
Actually, once the prop comes unstalled (around 7-8mph), the air is
blowing through the prop from *ahead* at all times.
Once wind speed and above is achieved, the *entire vehicle* is seeing
apparent wind from ahead.
JB
Mark Borgerson
@m17g2000prl.googlegroups.com>, ThinAir...@aol.com says...
I think one of the key pieces of data has not been discussed.
Did you have torque and RPM sensors on the shaft at either
the propellor or the wheels? With those sensors you could
record the power being transmitted through the drive system.
I would love to see a plot of that power transmission as
a function of time, vehicle speed and wind speed.
That torque data would settle any arguments over whether
the wheels are driving the propellor, or the propellor
is driving the wheels.
Mark Borgerson
ThinAirDesigns
> Did you have torque and RPM sensors on the shaft at either
> the propellor or the wheels?
When we had the vehicle on the dyno we had recording sensors on but
prop hub and drive axle for the purposes of optimizing our propeller
and gearing.
http://www.youtube.com/watch?v=5JjXudThU88
Once off the dyno we didn't carry that data collection effort on to
the desert as we had what we needed.
One doesn't need hub data to know that the rotor can't be driving the
wheels -- just look at the pitch and direction of rotation. If I
stick a house fan out in a stiff headwind it will rotate one direction
-- power it up and it will turn the other way. It's not hard to
predict what will happen even before we step outside. This is no
different.
JB
Wayne.B
>It's been proved possible by DOING IT.
>
>http://www.wired.com/autopia/2010/07/its-settled-downwind-faster-than-the-wind-officially-possible/
It turns out that Stan Honey was involved in this effort at its
inception. Stan of course is a world class sailboat navigator and
all around technical guru with many innovative inventions to his
credit including the "glowing" hockey puck and the orange superimposed
first down line on football broadcasts. I met Stan once in Bermuda
after a Newport-Bermuda race. Interesting guy.
http://www.wired.com/autopia/2010/06/downwind-faster-than-the-wind/
brian whatcott
/snip/
>>> how much thrust does your partner think is available when
>>> traveling at 40 MPH in a 20 MPH following wind?
>>
>> At 2x we are producing about 60-70lbs thrust.
>
>
> I think one of the key pieces of data has not been discussed.
> Did you have torque and RPM sensors on the shaft at either
> the propellor or the wheels? With those sensors you could
> record the power being transmitted through the drive system.
> I would love to see a plot of that power transmission as
> a function of time, vehicle speed and wind speed.
>
> That torque data would settle any arguments over whether
> the wheels are driving the propellor, or the propellor
> is driving the wheels.
>
>
> Mark Borgerson
>
>
The design is simple: an inclined shaft is supported on floats.
The lower end supports a small water propeller.
The upper end supports a wind turbine
(popularly called a 'propeller' also.)
The wind turbine is at the rear, where its drag points the float into wind.
The water propeller is at the nose where it drags the float forward.
I suspect there is a comparability in the modes of the two vehicles.
Brian W
ThinAirDesigns
> It turns out that Stan Honey was involved in this effort at its
> inception.
Yes, this project would not have existed without Stan (my boss for
many years). Stan is pretty much the most sought after navigator in
sailboat racing currently having set numerous records, won the Volvo
and current shareholder of the Jules Verne trophy (they smashed the
around the world record just a few months ago). He now works for
Larry Ellison on the America's Cup defense team. I'll be working with
Stan all this week as a consultant to the BMWO team (we go test
sailing with him on Thursday).
Bob parks, Chief Engineer for Aurora Flight Sciences (http://
www.aurora.aero/) and co-designer the legendary Daedalus (along with
MIT professor Mark Drela), was also part of the team.
Many other sharp people contributed.
JB
ThinAirDesigns
> The upper end supports a wind turbine
> (popularly called a 'propeller' also.)
You have to be careful not to confuse what might be "popular" and what
is correct.
Propellers and turbines are absolute opposites in many, many respects
-- they just both happen to spin.
> I suspect there is a comparability in the modes of the two vehicles.
They both slow down the air relative to the surface -- that they have
in common. Beyond that they are polar opposites in that the to go
downwind rather than upwind on *must* invert the prop/turbine
relationship.
JB
ThinAirDesigns
> Bob parks, Chief Engineer for Aurora Flight Sciences
>Daedalus (along with MIT professor Mark Drela), was also
>part of the team.
I need to clarify something I said above that could be confused due to
my poor wording.
Bob Parks co-designed the Daedalus along with Mark Drela -- Bob was
involved in our project, Drela was not.
JB
brian whatcott
There's a reasonable comment! I guess that means when the
sandyacht in question goes from a tail wind, to a headwind, as it must,
then its turbine becomes a prop? :-)
Brian W
cavelamb
Your explanations of a technical process are weak.
It seems like you don't really understand what was done very well.
Why are you starting this kind of argument all over the net?
What do you hope to gain?
We don't see Bob Parks doing this kind of thing.
(and yes, I already knew who he is)
It looks like someone felt like he was getting left out of the glory.
I wonder why...
--
Richard Lamb
Wilbur Hubbard
news:5JydncasGdpYOsjR...@earthlink.com...
He's more likely doing a study on how technologically ignorant and physics
challenged, not to mention how gullible, people are these days. It always
amazes me how many so-called intelligent people fall for such an obvious
ruse.
Wilbur Hubbard
ThinAirDesigns
> Your explanations of a technical process are weak.
> It seems like you don't really understand what was done very well.
Don't confuse you not understanding with my understanding being weak.
> Why are you starting this kind of argument all over the net?
Your observation skills are very weak - you should notice that I
didn't start the argument.
JB
ThinAirDesigns
> sandyacht in question goes from a tail wind, to a headwind, as it must,
> then its turbine becomes a prop? :-)
The rotor on the vehicle in question never operates as a turbine at
all. It would require a slightly different transmission method and a
broader range of variable pitch on the rotor than we equipped it with
to do so. It we had equipped it with such, it would have accelerated
up to wind speed quicker than it does now -- but the top end would
have suffered a bit. We were only interested in the top end so we
saved the weight.
JB
Justin C
> Casady:
>>The air is blowing through the prop from behind at all times.
>
> Actually, once the prop comes unstalled (around 7-8mph), the air is
> blowing through the prop from *ahead* at all times.
How can the prop, when moving forward at 7-8mph, be seeing wind from
ahead when the wind is from behind at a greater speed? There is no
headwind until you are going faster than the wind.
Justin.
--
Justin C, by the sea.
cavelamb
Oh, it's real.
They actually have done what he claims.
Supposedly all the details are posted on Rick Cavelero's blog, but I've not been
able to find it anywhere...
This is the address for what looks like the documentation on the project.
http://www.fasterthanthewind.org/
It is horribly designed.
I backed up through dozens of pages of stuff and never came to the starting
point. But there is some really interesting stuff if anyone wants it bad enough.
But I don't see much involvement by JB except as a mechanic.
http://www.nalsa.org/
http://www.huffingtonpost.com/2010/07/06/wind-powered-car-travels_n_636871.html
http://www.wired.com/autopia/2010/07/downwind-faster-than-the-wind-possible-and-theyll-prove-it/
http://www.fasterthanthewind.org/
--
Richard Lamb
cavelamb
You brought it here.
And you have a trail a mile wide all over the net.
--
Richard Lamb
ThinAirDesigns
> ahead when the wind is from behind at a greater speed?
Propellers suck in air from the front and expel it to the rear --
that's what they are designed to do.
Park a Cessna on the runway in a tailwind and slowly throttle it up --
at some RPM (depending on the strength of the tailwind, etc) the
airflow through the propeller disk will totally reverse and the
airflow will be aft (against the true wind). This doesn't mean there
is no longer a tailwind, it just means that the prop is spinning fast
enough that the thrust can now reverse the flow.
Same with the vehicle -- at something near 50% of WS, the RPMs of the
prop get high enough that the flow reverses.
JB
ThinAirDesigns
> You brought it here.
LOL -- you might want to run that by the poster who started the thread
and the half a dozen or so folks who were posting before I got here.
Y'all are a hoot.
JB
Sir Gregory Hall, Esq.
news:3efee627-a95b-47c7...@u4g2000prn.googlegroups.com...
> Propellers suck in air from the front and expel it to the rear --
> that's what they are designed to do.
That's what they do when they have a 500 HP Lycoming spinning them.
> Park a Cessna on the runway in a tailwind and slowly throttle it up --
> at some RPM (depending on the strength of the tailwind, etc) the
> airflow through the propeller disk will totally reverse and the
> airflow will be aft (against the true wind). This doesn't mean there
> is no longer a tailwind, it just means that the prop is spinning fast
> enough that the thrust can now reverse the flow.
Yes, because of that 500 HP Lycoming. Try it using the wind currents alone
and you get nothing of the sort even in your wildest dreams, Seamus.
> Same with the vehicle -- at something near 50% of WS, the RPMs of the
> prop get high enough that the flow reverses.
<lol> Where does the HP come from to do this? Certainly not from the wind
blowing on the structure of the vehicle.
You are such a moron troll. Too bad your audience is even more moronic,
Seamus.
--
Gregory Hall
Sir Gregory Hall, Esq.
Google Seamus MacRae. It's him using another nym. I can recognize his style
anywhere. He's one of the more accomplished Usenet trolls.
--
Gregory Hall
ThinAirDesigns
> Google Seamus MacRae. It's him using another nym. I can
> recognize his style anywhere. He's one of the more accomplished
> Usenet trolls.
Well then, if that's the case then this Seamus MacRae dude is
certainly not anonymous now in any way.
http://www.fasterthanthewind.org/
http://www.fasterthanthewind.org/2009/10/john-borton-jb.html
With that information you could have "Seamus MacRae's" office phone
ringing 5 minutes from now.
JB
PS: It's not the case.
Bruce in Bangkok
<ThinAir...@aol.com> wrote:
>> You have said that the propeller is driven by the wheels
>>and that the propeller is what is powering the vehicle.
>
>The propeller is driven by the wheels, and the thrust of the propeller
>pulls the vehicle forward -- the wind powers the entire process.
>
>>You have also said that you sometimes
>>pushed the vehicle to get it started.
>>Now you say that only the wind energy is
>>accelerating the vehicle.
>
>That is correct -- it *can* start on it's own (http://www.youtube.com/
>watch?v=5CcgmpBGSCI), but sometimes we push it to save the time it
>takes to get that first few mph. We'll do this primarily when we are
>testing in a short course -- if we push to few mph we can cut about a
>half mile of the course we need to get up to speed. If the course it
>long enough we'll generally do like we did in the above record video
>and let it start on it's own.
>
>NALSA rules allow only 'human on foot' push starting.
>
>> There is something wrong with your explanation.
>>
>> If, as you say, only the energy removed form the wind moves the
>> vehicle then there is no requirement for the propeller, is there?
>
>There is certainly a requirement for the propeller if you want to go
>DDWFTTW. Without the prop you would never even get to windspeed. The
>prop is the device that allows you to remove energy from the wind
>while at and above WS.
>
>> If, on the other hand, if the propeller is driven by the vehicle's
>> wheels than you are at least part of the time utilizing the energy
>> stored in the vehicle ( mass x Velocity2) to drive the propeller.
>
>If the wind lulls and we are *coasting*, then of course that is true.
>That is why NALSA rules say that this stored energy can't be used to
>*accelerate* the vehicle. This stored energy can't help you go
>faster ... only coast further.
>
>> But in essence you are saying that the wind propels the vehicle at,
>> say 1 MPH, which turns the vehicle wheels, which drive the propeller
>> with enough energy that the propeller accelerates the vehicle to 1+
>> MPH.
>
>During the start, that is in essence what happens (though it takes
>more like 7-8mph before the propeller comes unstalled at all). Once
>at or above WS, the chassis no longer providing any motivation from
>the tailwind.
>
>JB
My use of the 1 MPH figure was only to simplify my explanation.
Now, you say above that "the chassis is no longer providing any
motivation from the tail wind". However you have previously said that
movement of the chassis is what powers the propeller.
If the chassis is no longer receiving motivation from the wind what
force/power is powering the propeller?
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
Mark Borgerson
@l32g2000prn.googlegroups.com>, ThinAir...@aol.com says...
> > I think one of the key pieces of data has not been discussed.
> > Did you have torque and RPM sensors on the shaft at either
> > the propellor or the wheels?
>
> When we had the vehicle on the dyno we had recording sensors on but
> prop hub and drive axle for the purposes of optimizing our propeller
> and gearing.
So let's see that data!
>
> http://www.youtube.com/watch?v=5JjXudThU88
>
> Once off the dyno we didn't carry that data collection effort on to
> the desert as we had what we needed.
You may have what you needed. Others may not feel the same. A
direct measurement of the power being generated would seem to be
a very useful item. It allows you to make a confirming calculation
of efficiency and drag.
>
> One doesn't need hub data to know that the rotor can't be driving the
> wheels -- just look at the pitch and direction of rotation. If I
> stick a house fan out in a stiff headwind it will rotate one direction
> -- power it up and it will turn the other way. It's not hard to
> predict what will happen even before we step outside. This is no
> different.
>
That's a totally bogus analogy! If you face the fan so that air is
moving from the front of the vehicle to the back (to provide thrust),
then turn off the motor when the vehicle is moving faster than the true
wind, the relative wind will turn the fan in the same direction.
The small rotor fan is not well optimized for both providing thrust
and extracting energy from a moving airstream, but a larger propellor
could be more efficient. I think a key to getting good efficiency
in extracting energy from moving air is having a large rotor diameter---
wind energy systems seem to support that hypothesis.
Mark Borgerson
brian whatcott
Although not well- described - I believe the idea is that when the prop
turns, the relative wind is always from in front of the leading edge
over most of the blade at least.
Brian W
cavelamb
>
> My use of the 1 MPH figure was only to simplify my explanation.
>
> Now, you say above that "the chassis is no longer providing any
> motivation from the tail wind". However you have previously said that
> movement of the chassis is what powers the propeller.
>
> If the chassis is no longer receiving motivation from the wind what
> force/power is powering the propeller?
>
> Cheers,
>
> Bruce
> (bruceinbangkokatgmaildotcom)
I think a relevant point would be how many minutes (hours, days) it would
take this contraption to get up to 10 MPH without a push...
--
Richard Lamb
ThinAirDesigns
> I think a relevant point would be how many minutes (hours, days) it would
> take this contraption to get up to 10 MPH without a push...
Time it yourself to over 50mph untouched by human hand.
http://www.youtube.com/watch?v=5CcgmpBGSCI
(Filmed by one of our more noted skeptics btw)
http://www.fasterthanthewind.org/2010/07/video-from-richard-jenkins-world-land.html
JB
cavelamb
You sure have a lot of ego wrapped up in this.
--
Richard Lamb
Mark Borgerson
@sbcglobal.net says...
at a (slow) 1 rev/sec, the tips are moving through still air
at about 33MPH. A change in wind velocity from 15 mph from
ahead to 15 mph from behind shows up as a change in the
angle of attack of the blade tips. At slow propellor RPS,
that can mean a big change in the lift/drag ratio. At higher
speed (say 10 RPS), it won't have as much effect.
Mark Borgerson
ThinAirDesigns
> You sure have a lot of ego wrapped up in this.
You sure don't like to accept the reality of a vehicle accelerating to
well above 10mph in a period of time rather shorter than you so
pompously suggested.
JB
cavelamb
I don't care.
Bruce in Bangkok
I think that the main point is that you seem unable to explain in
either simple or complex terms exactly what is causing this vehicle to
exceed the wind, and when asked for an explanation you seem to dodge
and dart about avoiding any sort of technical description of the
experiment.
I suspect that at best you have created an earth bound Daedalus that
under a very limited and explicit set of conditions can exceed wind
speed but is essentially impractical.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
ThinAirDesigns
> I suspect that at best you have created an earth bound Daedalus that
> under a very limited and explicit set of conditions can exceed wind
> speed but is essentially impractical.
We have never once made a single claim as to the practicality of the
vehicle. We built it because people like you said it couldnt' be done
and we knew it could.
Nothing more ... nothing less.
JB
ThinAirDesigns
> I think that the main point is that you seem unable to explain in
> either simple or complex terms exactly what is causing this vehicle to
> exceed the wind, and when asked for an explanation you seem to dodge
> and dart about avoiding any sort of technical description of the
> experiment.
I presented a full set of force/energy calcs showing that at 2x
windspeed you can waste a full 50% of the energy available and still
maintain that multiple.
JB
ThinAirDesigns
> Now, you say above that "the chassis is no longer providing any
> motivation from the tail wind". However you have previously said that
> movement of the chassis is what powers the propeller.
Those are both correct, but perhaps I should have added the word
"relative" in front of the word "tailwind" to avoid confusion.
> If the chassis is no longer receiving motivation from the wind what
> force/power is powering the propeller?
At slow speeds (before the prop comes unstalled) the tailwind reacts
against the chassis of the vehicle pushing it downwind. As the
vehicle gets blown slowly downwind this drag gets less and less as the
apparent tailwind trails off. As the prop comes unstalled (at about
0.6 WS) and begins producing reasonable thrust, this thrust is
transferred through the prop shaft thrust bearing to the chassis.
As the vehicle achieves WS and above, there is no longer a relative
tailwind on the vehicle at all, but the thrust of the prop is still
pulling forward on the chassis.
JB
ThinAirDesigns
Livingston -- editor at Sail Magazine.
-
http://kimballlivingston.com/?p=3971
Bruce in Bangkok
No. Actually I never gave it a thought and all I have asked you for
was for a cognizant explanation for why it worked. Which, I might
mention, you have never provided.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
ThinAirDesigns
> No. Actually I never gave it a thought and all I have asked you for
> was for a cognizant explanation for why it worked. Which, I might
> mention, you have never provided.
Well, other than the full set of accurate energy/force calcs showing
that you can throw away 50% of the available power to losses and still
maintain 2x the windspeed -- yeah, other than that I've never provided
it (rolling eyes).
JB
Wayne.B
<brucein...@invalid.com> wrote:
>No. Actually I never gave it a thought and all I have asked you for
>was for a cognizant explanation for why it worked. Which, I might
>mention, you have never provided.
Let me try.
1. Motion is initially started by the force of the wind against the
vehicle.
2. Motion of the vehicle is transferred first to the wheels and then
to the prop via the chain drive.
3. The prop turns and creates thrust towards the rear of the vehicle.
4. Prop thrust increases acceleration, translates to increased speed,
which translates to increased thrust.
5. Vehicle eventually approaches TWS but since it is still moving,
the prop is still creating thrust.
6. As long as available prop thrust is greater than drag, the vehicle
continues to accelerate. (Vehicle design has obviously tried to
minimize drag to the maximum possible by the use of aerodynamic
shapes, light weight and narrow high pressure tires)
Bruce in Bangkok
Which is essentially what I said, originally, and was told that I was
wrong.
As I said, I never worked up any great interest in the possibility of
sailing downwind faster then the wind speed and after being exposed to
the people who claim that they have done I'm even less inclined to get
worked up about it.
(besides, I now have a motor boat :-)
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)