Is it possible to go DDW faster than windspeed?

[Guest Rocket]

I am with wheels looks like a con

[wheels 543]

"THE" website. Great pics and Vid.

http://www.fasterthanthewind.org/

 

Oh I am not saying it is a Con either. I just think there is something we are not seeing or being told. Certainly there is some very big bucks going into this. They have certainly come up with a vehicle thats seems to be being powerd by the wind in a way we have never seen before. But I think they have simply gained efficiency on the principle behind why boats like the AC boats can go fster than wind speed, and being able to do that on land. I wonder how much of an influence the verticle wing has?? Because that is one reason the AC boats or any yacht for that matter can travel forward. The Hull, Keel, Rudder and Sail is a wing that "lifts" in the direction we want to go.

[Guest]

I think of it this way.... The blades of the propellor are the wings that are giving lift in the direction you want to go. They are all on a beam reach...

The difference here is that the keel (wheels) is not resisting the lateral force of the wing, it is resisting the forward force of the wing. So, the vessel travels sideways down wind instead of forwards across the wind... Yet, the fact that the wing is spinning means you are still getting the same lift as if you were bean reaching.

[Guest]

The wind indicator on the craft is not used as the reference for the test results. They are in the following car. The results used for the record were 4 degrees off DDW.

 

From reading the example I posted this is what I get;

1.The craft can start from standing start from the wind blowing on the craft, but it is quicker to give it a push.

2.The wheels are then converting the forward motion into propellor rotation through the gears.

3.The propellor then creates a small amount of forward thrust which creates acceleration.

4.Back to 2.

[Guest Rocket]

I reckon you build a light cart with most of the mass in the wheels and the propellor axle - basically an inertia battery like they tried to power cars with back in the 90s. Then hold it on the running tredmill to load it with kinetic energy. Then slowly turn down the speed of the treadmill - it will climb....

 

The equivalent on the road test would be a drop in windspeed once it was moving.

[Variant 2]

What everyone is failing tounderstand is that as the vehicle apporaches windspeed, where is the energy coming from? You have to have energy to spin the prop or turn the whees faster than the wind and thus producing more ergy than is being applied.

Either the prop is turning the wheels, or the wheels are turnign the prop. Either way, either has to providing more energy than is being put into them.

 

At windspeed (zero apparent wind) you still have the blade spinning which is still being pushed by the true wind.

[Guest Rocket]

At windspeed FRDDW there is no apparent wind so what is doing the pushing?

[Variant 2]

At windspeed FRDDW there is no apparent wind so what is doing the pushing?

 

True wind is still pushing on the blade because it is spinning against true wind.

[Grinna 2]

But if you're moving forward at wind speed, then the true wind from behind is cancelled by the apparent wind created by forward movement meaning that there is no effective movement of air to push on anything. The wind from behind equals the wind from in front and they cancel each other out.

[BelowPAR 0]

Hahaha i asked the lectuter after the exam. He told me that he thought i had misread one of the questions .

 

I can almost get my head around the fact that windvelocity vectors are almost arbitrary (for example when you take apparent forward i can see no reason why you can not be sailing dead down wind (TWV) faster than the wind, thats all relative motion / translating axis stuff (previous exam) but engineering design limits that theory a bit)

 

But the process of how these chaps are doing it is confusing me...

More reading to go! (something to fill in 4 months holiday )

[Guest Rocket]

The blade is moving at the same speed as the true wind so there ain't no pushing going on.

[smithy09 50]

Relative to apparent wind (zero when cart is at true wind speed) there is still thrust from the prop. I still reckon it's not a hoax. Just a mind bender.

[smithy09 50]

With regards to the energy equations, it's the same as land yachts going nearly DDW at multiple times the speed of the wind. They are actually more efficient than this beast, as they certainly exceed 2.8 x the wind speed.. Where do they get their "extra" energy from?? They get it from the apparent wind they create from their forward motion.. More forward motion = more apparent wind until you catch up with the forces holding you back which are mechanical losses and drag.. What's the difference? More forward motion in this case = faster prop speed. Same deal.

 

Maybe you have to be not so smart to understand this one? It's the clever guys that have the most difficulty getting their heads around it!

[Guest Rocket]

What thrust from the prop - the prop is spun by the apparent wind, when cart speed equals windspeed there is no apparent wind therefore there is no thrust...

 

I understood we are not talking about going nearly DDW we are talking about going exactly DDW. Maybe its semantics?

[Guest]

The prop is being spun by the wheels not the wind.

If you think about it any other way you are barking up the wrong tree.

[smithy09 50]

What thrust from the prop - the prop is spun by the apparent wind, when cart speed equals windspeed there is no apparent wind therefore there is no thrust...

 

I understood we are not talking about going nearly DDW we are talking about going exactly DDW. Maybe its semantics?

 

The prop is driven by the wheels. They have a ratchet to ensure that the reverse cannot happen. That is the whole guts of the thing. The energy that is taken up by the losses in the prop and mechanical transfer is provided by the tail wind.

 

The land yachts can go DDW from what I understand, but they cannot get there just pointing straight downwind.. I think I have that right.

[Guest]

Land yachts can only go to within 15 degrees and still accelerate.

[wheels 543]

It doesn't matter what is driving what. Wheels or prop or whatever. At the point of where the wind speed or pressure or energy, whatever you call it, is equal, to forward all of the aboves, then you have no driving force. It does not matter what the wheels are doing, something has to impart energy into those wheels to impart energy into the prop to propel it forward. The prop can not produce energy to propel it forward if the wheels are not recieving energy. But that is just one point of end of story. This thing takes the story further by then moving into a head wind. So what is turning the prop now?? Because now you are using an opposing force to than used to get moving. So OK I could handle the idea of reaching 100% downwind speed...at a push. But I can not believe that with nothing changing, you can now push into the wind and accelerate.

 

But hold up the horses. I thought this was all about directly down wind. No angles. But in fact that is not true then. 4deg angle is not direct down wind. If you start talking angles, then everything changes.

If you look at the wind direction indicator on the support car, it is even more than 4deg. So what gives here. Is it DDW or an angle to the wind.

[smithy09 50]

Wheels, have a look at the links. They have reports from observers, name them etc etc. These guys are bona fide.

The record rules say that it must be within 10 degrees of DDW. I think it is quite hard to steer that exact...

The energy comes from the tailwind.. No tail wind, no go.. Same as a land yacht or windsufer going faster than the wind.. It makes its own wind and that's how it works, but the only energy obtained still comes from the wind. It's just a different way of converting it that we are not so familiar with.

When windsufers first got going really fast, a lot of people including myself struggled to understand how they were going on a broad reach with the sail sheeted in so hard.. Similar concepts.. How can you go faster than the wind??

[smithy09 50]

Good link to Wikipedia:

http://en.wikipedia.org/wiki/Sailing_faster_than_the_wind#Sailing_dead_downwind_faster_than_the_wind