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New Speed Record Set For Wind-Powered Vehicles
Hugh Pickens writes "Richard Jenkins reached 126.1mph in his Greenbird car on the dry plains of Ivanpah Lake in Nevada, setting a new world land speed record for a wind-powered vehicle. 'It's great; it's one of those things that you spend so long trying to do and when it actually happens, it's almost too easy,' says Jenkins. The Greenbird is a carbon fiber composite vehicle that uses wind (and nothing else) for power. The designers describe it as a 'very high performance sailboat,' but one that uses a solid wing, rather than a sail, to generate movement. Due to the shape of the craft, especially at such high speeds, the wings also provide lift; a useful trait for an aircraft, but very hazardous for a car. To compensate for this, the designers have added small wings to 'stick' the car to the ground, in the same way Formula 1 cars do. 'Greenbird weighs 600kg when it's standing still,' says Jenkins. 'But at speed, the effect of the wings make her weigh just over a ton.' Jenkins has also built a wind-powered craft that travels on ice, rather than land. 'Now that we've broken the record, I'm going back on to the ice craft. There's still some debate as to whether traveling on ice or land will be faster.'"
Obviously, they've never seen Aunt Flo's old Desoto with the busted crankshaft flying down the street during hurricane season ...
I hate breaking out the calculator to compare 600kg to a ton. Relative increase, I guess.
The cost of that cleanup, of course, will be borne by taxpayers, not industry.
30-40mph with gusts later in the day higher.
though on land it is easier. on water the record is about 64mph in 24mph wind.
okay so i am a sailing geek. I also say this yesterday.
i thought once I was found, but it was only a dream.
Weight and mass are different things. Their usage is correct.
Their usage is dead wrong. Weight is the effect of gravity on mass. The vehicle doesn't "weigh" more at speed - the effect of gravity on it hasn't changed. It just generates a down-force from the wing. To say that it weighs more is about as accurate as saying your weight changes as you jump up and down on a scale, or that an airplane weighs less than nothing when it's flying.
Since energy can be converted to mass, they would have to be going at a large percentage of c to actually "weigh" more.
Right - weight is the effect of gravity on an object of a specific mass. The effect of gravity doesn't suddenly change at speed. The vehicle dos NOT weigh more - gravity's effect on it is constant. What changes is the aerodynamic down-thrust. That doesn't change the vehicle's weight, just as an airplane doesn't suddenly weigh less than nothing when it takes off ... gravity still has the same effect on its mass.
Not quite. The downward force when it is stationary is 600gN, the downward force when it is moving is 1000gN. The downward force due to gravity, also known as the weight, in both cases is 600gN. The mass in both cases is 600Kg. Neither the weight, not the mass, change. The mass could only change as a result of things being added to or removed from the vehicle, or as the result of relativistic effects (which are present at the recorded speed, but not significant enough to be measured). The weight could change if the mass changed, or if the vehicle climbed far enough from the centre of the Earth for the inverse-square attraction to be reduced (again, this is unlikely to happen unless it raced up a steep mountain; g varies a bit, but not enough to be worth bothering about, over the surface of the Earth). The downward force can change for a wide variety of reasons, but in this case due to a pressure differential caused by air moving more quickly over the underside of the stabilisers.
Note: In this post, g is used as little-g, the acceleration due to gravity on the surface of Earth, while g is the SI unit gram. This is not quite standard notation; they should both be represented by the same symbol, which is just plain confusing.
I am TheRaven on Soylent News
And in Ontario, you'd be able to get your licence suspended for a week, and car impounded, all without burning a drop of gasoline.
Yet, if you pay no attention, drift 10 feet out of your lane, roll your vehicle, and kill two people, you can legally drive away from the accident scene.
Go figure......
"City hall" in German is "Rathaus" Kinda explains a few things......
This craft reminds me of the early Michael Moorcock SF story The Ice Schooner:
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make install -not war
Since energy can be converted to mass, they would have to be going at a large percentage of c to actually "weigh" more.
That's a non sequitur. Fast moving bodies do not have a higher "effective mass" because some of the energy is converted into mass. It's just an interpretation of the fact that as you approach c it takes more and more energy to accelerate. Another interpretation is that the mass is constant and the momentum does not depend linearly on velocity, but approaches infinity as the velocity approaches c.
Those who would give up liberty to obtain working drivers, deserve neither liberty nor working drivers.
The downward force on the surface it is sitting has increased, which is the point they are trying to get across.
Stop being a pedantic ass.
growing up, we used to race a DN class iceboat. IceMice could do over 70 mph in a 30 mph wind. This is another 50 mph faster. Tip the craft on dirt, and you will know it.
I prefer the "u" in honour as it seems to be missing these days.
Interesting, but totally useless for cars. The wing is way too tall for traffic. But for ships, its a different story. Question is: If it takes a 40 foot high wing to move a 1 ton car, how big of a wing would you need to move a 50,000 ton container ship? The heaviest sailing vessel yet constructed is the Star Clipper: Star Clipper, which is 5000 tons and traditionally rigged with about 50,000 square feet of sail handled by 20 crewman.
This is my sig.
The physics that allows one to sail faster than the wind aren't completely obvious. Terence Tao wrote a very good explanation of the basics http://terrytao.wordpress.com/2009/03/23/sailing-into-the-wind-or-faster-than-the-wind/ where he also shows a nice theoretical construction that allows one to accelerate to any speedy (assuming that the universe is Newtonian).
Did they take the average of two timed runs in opposite directions in order to compensate for, you know... wind speed?
Set your phasers on "funky"!
In practice people will hardly ever use your POV that weight is solely the effect of gravity on mass, since it's not that useful.
For most people, weight means "apparent weight". The force that a weighing scale (theoretical or otherwise) would measure if you could put the object on it.
Which in many circumstances will be something like:
mass * acceleration due to gravity - bouyancy due to fluid/air the object is in - the force due to the earth spinning + "other stuff".
"other stuff" could include downforce.
This is more useful since the object could break stuff it goes over if the "practical weight" is too high even if the m*g is less than the limits.
For example, for the speed record on ice attempt, they'll have to figure out whether the ice can take the max "apparent weight".
IMO, weight= m*g is best left for high school physics. People dealing with stuff in the real world will use weight = "apparent weight".
And they're not going to use two words where one word will do.
The "weight = m * g" definition is not very useful.
The only use for that definition I've had is in high school physics exams.
The more useful definition is weight = "apparent weight".
Where weight = the actual force the object would exert on the surface it's on.
And that is not m * g.
It's m * g + downforce - bouyancy - force due to the earth spinning, and all sorts of other stuff.
The CHP clocked me @ 47mph on a Big Wheel. It was downhill, however, and definitely not the record. One of my friends was clocked @ 55 going down Corral Hollow road towards Carnegie. The guy in the car couldn't keep up once they got into the twisties. Its a miracle that we survived our childhoods.
The cost of that cleanup, of course, will be borne by taxpayers, not industry.