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Wind-Powered "Greenbird" Seeks Land-Speed Record
Mike writes with this tantalizing excerpt: "Dale Vince of Ecotricity and engineer Richard Jenkins are setting up on the salt flats at Lake LeFroy in Western Australia, hoping to catch the right breeze and break the wind-powered landspeed record of 116.7 mph in their sleek wind-powered vehicle, the Greenbird."
Can someone explain how they could travel 3 to 5 times faster than the wind is blowing? I'm thoroughly confused on how that's possible. Is the vertical wing producing less air pressure towards the front providing forward momentum?
It looks like something I built with tinker-toys once. I hope theirs holds together better than mine did.
I mentioned tinker-toys once in a post - now I'm modded down for life.
You may not know, since your hobby seems to be bitching about the accomplishments of others, but when you try new things, you tend to learn new things.
Things that can be put into practice in other ways.
Well, if you've ever seen the Coyote and Road Runner Cartoons, you'll know that the crew on the boat blows really hard into the sail, thereby creating a much larger velocity associated with the relative wind, increasing the "lift" of the sails and thereby propelling the craft faster than the wind. Now, if you place a large amount of ACME TNT behind the craft, the crew, out of shear terror, will blow even harder and thereby adding a few more knots to said velocity of the craft.
They use a rocket engine. The fuel was derived from oil, which used to be dinosaurs. The dinosaurs used the wind (or "air") to breath, and the plants (and other dinosaurs) they used for fuel also used the wind in a similar fashion. Thus, the vehicle is technically powered by wind.
See? This green stuff is easy if you just put a little thought into it.
Yes, I know how this is possible, and if you took elementary physics, you should be able to figure it out.
I'll give you a line of thought to follow, to get you started.
What happens when the wind hits the sail? Force is exerted on the sail, which is transferred into forward momentum of the vehicle. What happens when the wind hits the sail from directly behind the vehicle (in relation to its path)? What is the force exerted by the wind on the sail when the speed of the vehicle is equal to the speed of the wind?
OK, now what happens when the wind is coming from an angle (say, 45 degrees)? And what happens when the speed of the vehicle is equal to the speed of the wind? What force is exerted on the sail then?
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
In sailing you have something called apparent wind. This is the direction and speed the wind appears to be coming from as the vessel moves. As the vessel moves faster and closer to the direction of the wind (modern sailboats can travel close to 30 degrees off the direction of the wind) the apparent wind increases in speed and moves more towards the front of the vessel.
The thing that they are really having to fight with here is drag and downforce. The faster they go the more the wind is trying to flip the boat sideways.
http://en.wikipedia.org/wiki/Apparent_wind
I took a course on sailing once. The instructor was fond of pointing out that a sailboat is actually sucked forward rather than blown forward. Repeatedly. I think this guy may have had issues beyond a fuzzy understanding of the physics involved but he wasn't totally off the mark either.
This ain't rocket surgery.
you use a more than 1 sail to catch the deflected wind. I just googled it and came across this page.
http://www.physclips.unsw.edu.au/jw/sailing.html
How much is your data worth? Back it up now.
not good
It doesn't have a sail. How does it go?
Someone tell me how stupid I am.
"Computers are useless. They can only give you answers." - Pablo Picasso
From TFA:
The team plans to take the knowledge they gain from these experiences and apply it to the real world, incorporating aspects from the design into the next generation of vehicles and micro turbines.
So there may be something useful achieved. But even if not, it's still a pretty cool thing. Besides, not everything has to be useful.
I think you need to get out more.
This ain't rocket surgery.
I think you need to get out more.
He can't afford to, if he's going to continue being constantly useful!
The enemies of Democracy are
A lot of knowledge is gained by these types of endeavors. Even if they seem pointless.
Why do motor companies continue to invest in various forms of automotive racing? It isn't like they can sell F1 cars to very many people? They do it because they can learn things under extreme conditions. They learn about tire wear, aerodynamics, engine performance, etc. (and of course, they also get brand exposure, but that is a side benefit).
Setting the wind powered land speed record will aid in aerodynamics, harnessing wind (which could be useful in converting it to electricity) and I'm sure several other areas. And in the process, they get to put their names in the news (and possibly the book of world records).
And besides, have you ever written a program "because you can" or maybe modded a case "because you can" or built a robot "because you can"?
Layne
For more information, people can go to the Greenbird web page or to the relevant wikipedia page.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
No, you just sail. One may sail faster than the wind in a craft with only one sail.
everything in moderation
They didn't teach physics at my elementary school. :(
The wind pushing you forward creates another wind because you are moving through the air. Imagine coasting down a hill on a bicycle or skateboard. If the wind directly behind you is pushing you at the same speed, they will cancel each other out. So you hit the wind at an angle so the wind created by you moving through the air isn't clashing and canceling each other out. Now, they trim the sails into a wing of sorts that instead of being pushed, it is actually being pulled by lift. As long as you are moving in a direction the lift increases by the surface area of the wing and the angle to the wind.
This is also how a sail boat can sail into the wind. Although there, it is very inefficient and they don't get a lot of speed. But the answer is that the sail becomes a wing that creates lift along it's axis which is vertical and ends up getting pulled by the lift more then pushed by the wind.
This is also a main difference between a fan and a propeller on an aircraft. The propeller is shaped like a wing so the lift gives you more forward movement (power) then the friction of air crossing the blades and being pushed behind it. If you were to fit a fan with a propeller and make it turn at the same speeds, it would pull the fan over.
I realize now that I mis-interpreted my original reading of that page. Thanks for having me go back and check it over!
How much is your data worth? Back it up now.
What does this engineering-masturbation have to do with transportation? It's not like it's useful for anything other than some weird bragging rights.
Well, since engineers can't get girlfriends, what other outlet do they have?
un-ALTERED reproduction and dissimination of this IMPORTANT information is ENCOURAGED
I had a physics teacher who was fond of screaming "THERE IS NO SUCH THING AS SUCK!" repeatedly.