How can an vehicle move faster than the wind that is powering it?

[rcgldr]

So, if it experiences 0 wind speed and 10mph belt speed then what is it that is powering the propeller. Since ThinAirDesigns hasn't answered, I pose the question to you Jeff.

Great, and I'm still not convinced it works yet. Start with a simpler case, a very long treadmill, and the device has drag inducing device, say a parachute or a solid disk. The air applies a forwards force to the device, while the treadmill applies a backwards force to the device. In this case the wheels could be connnected to a generator which would create power. The point here is that if the cart is moving slower than the belt speed due to aerodynamic forces, then power from the wheels can be harnessed.

The next leap of faith is if the wheels power a propeller, can the propellor operate in an "apparent wind" situation that allows the propellor generate thrust at speed faster than the treadmill speed? Note that the source of power is the difference between wind and treadmill speed, independent of the device speed. Assuming the ice and land boaters aren't all involved in a hoax, apparently those devices can travel downwind faster than the wind speed, as long as they have sufficient cross wind speed.

Again, my issue is that the propeller is operating in it's own induced wash, which limits it's efficiency, so I don't know if the efficiency issue is enough to keep it from working.

 

[PhysicsAddict]

The air applies a forwards force to the device

Jeff,

This could only be true if the device is moving. Think of it like this: When you are running on the treadmill at 10mph in a room with still air does the air pressure on your back assist you IN ANY WAY at maintaining your forward speed? Before you answer, remember that the air pressure on your front side is exactly the same.

If you use a generator and a motor and a drogue chute you are only obfuscating the model. Simply go back to the original model I stated. Can you continuously absorb 10N of force from the belt and use it to continuously produce 10N of thrust in order to stay stationary on the belt?

Even though I have thought about it, I haven't even addressed the issued of it churning through it's own ring vortex yet. I think that only puts more nails in it.

Edit:

Keep in mind that I do not believe that the entire land sailing community is in on some sort of hoax. If it is indeed possible that iceboats can develop a downwind VMG greater than wind speed then I believe that we are all missing something as we collapse the model down to a cart on a treadmill.

I just need simple answers to simple questions like the ones I have asked in order to find the kink.

 

[ThinAirDesign]

Sorry guys. I didn't drop out of the exchange ... had to do some real work.

I'm enjoying the tone of the discussion and will return.

JB

 

[spork]

Since you now understand these two simple ideas, you can now conclude that the video can only be either:

A. A hoax.
B. Some other "artifact" captured on film.

Well, since you've be able to prove this impossible with absolute simplicity and certainty, you should let me hook you up with this $100K bet. How would you like some free money?

 

[Trond]

Can you continuously absorb 10N of force from the belt and use it to continuously produce 10N of thrust in order to stay stationary on the belt?

No, not if you count in friction and apply those 10N on something also rolling on the belt.
However if you apply those 10N on something that is standing still (the air) then that is a completely different matter.

Spork actually gave a good example with a yoyo. Put it on the table with the cord coming out under it. Make sure the yoyo has a few turns of the cord at least. Pull slowly so it doesn't slip and watch the yoyo roll up the cord faster than you move the cord. The force you put on the yoyo's center by pulling the cord is transferred to the table and the yoyo moves faster than your pull.

 

[spork]

Not quite, the jet engine uses a compressor and heat to create a huge pressure jump. You'd need a strong power source and a prop with a pressure jump to higher than ambient to pull this off. A high efficiency prop wouldn't work, because the pressure jump occurs below ambient, and air is decelerating once it passes through the prop disk.

I'll locate the video link. A buddy did just this by sticking a small electric fan on a little cart. It certainly wasn't very efficient, but it worked.

Great, and I'm still not convinced it works yet.

Fair enough (although I assure you that it does). Are you convinced that an ice-boat can tack downwind such that its downwind velocity component is greater than the wind speed?

 

[Trond]

Is the bet really your only agenda Spork since you keep on asking about it or is it pondering about a problem which seem to drive the rest...I'm beginning to agree with the guy that mentioned nigerian scam on RR...it's boring.

 

[ThinAirDesign]

Back for a moment:

A serious question for PhysicsAddict and Trond. I need to know your stance before I can respond.

Are one or both of you stating that the cart will respond/behave differently on the street with a 10mph wind as compared to in the basement on a treadmill set to 10mph?

It appears that you feel it will act differently in the two environments.

JB

 

[ThinAirDesign]

Is the bet really your only agenda Spork since you keep on asking about it or is it pondering about a problem which seem to drive the rest...I'm beginning to agree with the guy that mentioned nigerian scam on RR...it's boring.

I think you will find that "the bet" is only on Spork's agenda when someone is only interested in stating with absolute certainty "it's a physics impossibility".

If the bet was Sporks only agenda, he wouldn't be interested in explaining how it works to people who hold at least a sliver of open mind that it might work.

After all, if they're not interested in an exchange -- only "it's violates the laws of physics", where else is there to go? It they're soooo right, it's easy money.

JB

 

[spork]

Is the bet really your only agenda Spork since you keep on asking about it or is it pondering about a problem which seem to drive the rest...I'm beginning to agree with the guy that mentioned nigerian scam on RR...it's boring.

The bet is for people that are positive this is impossible - people like you.

For those that want to discuss it, I think you can see I'll go to any length to describe how it works, provide analysis, give examples, etc.

What's boring is hearing from people who seem just as certain as I am until they're invited to put their money where their confidence is.

 

[nixy2]

I'll locate the video link. Are you convinced that an ice-boat can tack downwind such that its downwind velocity component is greater than the wind speed?

FWIW, Your vector diagram has convinced me you are right (I think). But also the vector diagram would also show an ice-boat can not go DDWFTTW, whereas the 'wind trolley' can?
With emphasis on the D

 

[rcgldr]

The air applies a forwards force to the device, while the treadmill applies a backwards force to the device.

This could only be true if the device is moving.

I was assuming the cart was moving in that example. Assume a long treadmill and nothing but air resisting the carts movement. The treadmill moves the cart backwards, and the air resists this movement with a forwards force. Assuming there is drag on the wheels, the treadmill exerts a backwards force onto the cart.

When you are running on the treadmill at 10mph in a room with still air does the air pressure on your back ...

The surrounding air isn't moving, only the air affected by the propeller.

Can you continuously absorb 10N of force from the belt and use it to continuously produce 10N of thrust in order to stay stationary on the belt?

Newtons' 3rd law at work here. The forces are always equal and opposite if the cart is not accelerating. The issue here is at what cart speed will the forces be equal? Can the forces be equal if the cart is moving forwards?

Back to the OP

How can an vehicle move faster than the wind that is powering it?

Because the source of power isn't the wind but the difference between wind speed and ground speed, which is independent of vehicle speed. The question is can the cart utiize this source of power while moving faster than the apparent wind on the cart, because the propeller blades experience a different apparent wind?

 

[ThinAirDesign]

If I run on the treadmill which is set to 10mph and I am in a room with still air do you think I feel a 10mph breeze on my face?

No.

The situation that you describe above is exactly the same as being on the street and running 10mph with a 10mph tailwind.

We really do need to get past this frame of reference issue before we move on -- it may well be a simple misunderstanding between us (and that may well be my fault).

This all started when Trond used the term "no wind" when discussing the cart on the treadmill. I'm just trying to make sure we are all using the term "no wind" the same. There's 'wind or not' relative to the chassis, 'wind or not' relative to the sails, 'wind or not' relative to the ground, 'wind or not' relative to the treadmill surface, and now there's 'wind or not' relative to my face. If when we say "no wind" and we don't establish *relative to what*, we can't have much of a productive conversation.

I don't mean to be difficult, but there can only be "simple answers" if all the small definitions are worked out.

JB

 

[PhysicsAddict]

Are one or both of you stating that the cart will respond/behave differently on the street with a 10mph wind as compared to in the basement on a treadmill set to 10mph?

It appears that you feel it will act differently in the two environments.

JB

And my answer is that I don't know for sure. Here is where I'm at:

1. The iceboaters of the planet certainly claim that a VMG downwind is a piece of cake. There's lots of them and only one of me so I'm inclined to follow along.
2. It would seem that you could take all the principles of the iceboats and squeeze them into a cart with rotating sails and the kinematic constraints of wheels to build a cart that will go DDWFTTW.
3. Jack Goodman claims to have built such a cart and posted the Youtube video which gets me excited but is hard to accept for documented evidence as "proof possible" since what we could be witnessing are artifacts of the experiment and like all good experiments really needs independent confirmation.
4. When I try to reduce it all down into an environment that would reduce the possibility of any such artifacts and would be much easier to test, control and document (the cart on a treadmill), I run into the issues I stated on my first post.

It is certainly a quandary.

After all, if they're not interested in an exchange -- only "it's violates the laws of physics", where else is there to go? It they're soooo right, it's easy money.
JB

You and I were having a nice exchange, Jeff and I were having a nice exchange. Nevertheless here we are with the betting.

I really only asked simple questions and expected only simple answers but the only one who would do so is you and Jeff.

Newtons' 3rd law at work here. The forces are always equal and opposite if the cart is not accelerating. The issue here is at what cart speed will the forces be equal? Can the forces be equal if the cart is moving forwards?

Hey! Just run the speed up on the treadmill until it appears to break even and there you have it. If you can get to that point I believe you can "go all the way".

What's boring is hearing from people who seem just as certain as I am until they're invited to put their money where their confidence is.

Why? How confident someone is on his/her position is irrelevant to this entire discussion. I know someone who was confident enough that the Patriots would win the Super Bowl that they dropped 25 large on it. It goes to show that how much money someone is willing to put on something has nothing to do with how correct they are. If you find it boring you should move along and we will continue to discuss it here.

This is a nice board and it appears to have lots of really bright contributors so I thought it would be nice to jump in the exchange here. I'm new here and only feel like I'm a guest so I am not going to hang around here while it turns into a slagging match.

Here is one thing I will leave you with:
I have now gone full circle on this. I originally argued that it was a "no-way no-how" thing. Then as it turned out to be possible with land yachts and iceboaters I could only believe that it's certainly possible to collapse it down to a cart heading directly downwind. When I saw Jack Goodman's video I thought "holy cow I got to build me one of those!" Then as I pondered the treadmill dilemma I started scratching my head again. But I didn't let it slow me down.

So here's mine:
http://s167.photobucket.com/albums/u123/DarwinAward/

I wish I had more but that was a hard drive crash ago. I built and rebuilt that cart 3 times after those pictures and video. Not shown in the photos or video is that in it's final form I could regear it at in only minutes. With the 4 sets of gears and 4 sets of wheels I had I could set it a full 300% above the cart pitch ratio that Mr. Goodman specified as well as 300% below. I had 5 different sets of blades including one homemade set laminated together using fanned out balsa that looked as close to Jack's as I could get. My cart had one other really nice attribute - I had variable pitch that I could adjust in real time. It was a blast to build and a blast to tinker on with one exception: it would never make forward progress on the treadmill.

But here is the thing that really bugs me: Jack Goodman built a cart and put it on a treadmill and he could run the treadmill from 0mph to 4mph where the cart would get lighter and lighter on the scale until it was "break-even" at 4mph. He could then increase the treadmill speed and it would increase the pull on his tensiometer as it would try to make forward progress on the treadmill.

I however, built my device and tested it using every combination of gearing, wheels, blades and pitch settings and in EVERY case my cart would only exhibit more force on the scale as the speed of the treadmill was increased. There was no combination of any of the variables that showed any promise of getting lighter on the scale as the treadmill speed was increased. Not only did I fail, I wasn't even in the ballpark.

The beauty of it all is that this only proves that I don't know how to build a cart that will make forward progress on the treadmill. I'll be the first to admit it. Whether it means that it is impossible to do or that I just suck at it I don't know. That is what is so cool about the whole deal - you can never disprove it but it may be possible to prove it can be done.

So here's my challenge to you, especially you "YaySayers": Get to it. What the hades is everyone waiting on? It didn't take me 4 hours to get it built the first time around and maybe $50 worth of old RC Helicopter parts. Go build one and put it on on a treadmill and give us some videos. I will certainly want to get with you afterwards and make mine work (no kidding, no sarchasim). Even if you are a "NaySayer" you will have a blast I promise. Just do it. Let me put it to you this way: I'd bet that there 100 folks on here and on 20 other forums on both sides of the argument that have spent 100 hours typing about it and STILL haven't run out to the shed and start wrenching about it! Go figure. Blows my mind.


Good luck and I will check back from time to time to see if anyone has gotten off of their lazy butts and posted up some videos!

 

[ThinAirDesign]

Hey PhysicsAddict, if you don't mind, I'd like to take you back to an earlier post of yours (quoted in full at the end of this post). I'm also going to reference a portion of an earlier post of mine.

The above is no different than taking two ice-boats on mirror zig-zag downwind tacks and placing a sliding beam between them -- give me two seats and a windsock right in the middle of the beam between the boats. You and I sit in those seats and watch the windsock. Yep, sure enough ... at the moment we reach the real wind speed, the sock hangs limp. Do the twin ice-boats that we are riding on care? ... of course not -- they are zigging and zagging and see plenty of wind as they accelerate us both to a VMG of greater that 1.0 and the sock turns into our face.

1: It's been established earlier in this thread via links to the NALSA website and forums that ice-boats and land yachts can and do regularly achieve VMGs far greater than 1.0. (if you don't agree, speak up now 'cause we need to backtrack and you might want to argue with them about it.)

2: Given "1", I would ask you to place the above twin ice-boats on your below treadmill (humor me please ... ok?). Remember, in the above scenario, you and I are sitting side by side between the boats(facing forward or downwind), riding an equally telescoping beam stretching from boat to boat, and we have a wind sock attached to our seat beam that is staring us in the face (in other words, it's operating in *our* frame of reference). We are in fact the *drivers* of this twin ice boat and our drivers seats are located in the exact dimensional, mechanical and CG center of this ship. We also happen to travel *directly* downwind.

In your below scenario, perform the exact same thought experiment with the twins as you do with the cart -- that is you and I take the twins up to the speed that the sock between us is hanging limp.

Now, apply all the same logic to the twins at this moment that you did to the cart (especially the part below that I bolded).

Of course, given "1", we both know that the twins will power right past this "zero" point and fill the windsock with what appears to us to be a headwind.

So now the question ... Are you and I, zipping across the ice with an apparent headwind (while actually having a ground referenced tailwind) a

A. A hoax?
B. Some other "artifact" captured on film?

Thanks in advance for your answer

JB

In order to understand this you need not understand sailing, relative wind, apparent wind or ANYTHING other than Newtons 1st law.

To get your head around this, imagine the cart facing west sitting on a long treadmill in a long windless hallway. Start the treadmill which runs towards the east and slowly increase the treadmill speed until the cart is at the perfect “break even” point. In other words, to an observer standing still in the hallway, the cart appears to also be standing perfectly still even though it is on the treadmill with its wheels spinning and propeller turning. This is the point where the cart goes EXACTLY as fast as the wind downwind. We don’t need it to go faster than the wind downwind yet. Right here at the break even point is the best place to get your head around it.

Now you don't need to understand anything more that two simple ideas:

1. You must understand Newton’s 1st law of motion - specifically pertaining to balanced and unbalanced forces. In order for the cart to appear to stand perfectly still on the treadmill, the forces pushing on the cart from the east must equal the forces pushing on the cart from the west.

In other words, let’s say that the treadmill is expending 10 Newtons of energy driving the cart east. Since the forces are balanced, the propeller on the cart must be expending 10 Newtons of energy driving the cart west in order to hold it stationary. Since the cart is not experiencing ANY wind pushing it at this point, all its energy driving it west must come from thrust generated by the propeller.

2. You must understand that mankind has yet to invent a machine simple or complex that outputs 100% of the energy it consumes. A propeller is at best 85% efficient. Add in the other components of friction and well it all goes downhill from there. In other words it would be impossible for the cart even get to this break even point. It will never generate thrust equal to the energy it consumes. Now to go even faster than the wind it will have to generate thrust IN EXCESS of the energy it consumes which of course is never going to happen.

Since you now understand these two simple ideas, you can now conclude that the video can only be either:

A. A hoax.
B. Some other "artifact" captured on film.

So here it is reduced to it's minimum components. Nothing to obfuscate here. Very simple.

If you contend that it is possible then all you need to answer is this simple non-obfuscated problem:

Let's suppose that the treadmill imparts a continuous 10 Newtons of force where the treadmill belt strikes the wheels. Please lay out the equations for me assuming your propeller is 90% efficient (that would be an awesome propeller BTW) and there is no friction in the inner gearing of the device. Show me where the device is able to generate continuous thrust in excess of 10 Newtons in order to break even and stand still.

It's a simple equation I assure you. If you need the equation I can point you toward it.

So if you would please lay it out for us where 10N into the propeller results in >= 10N of thrust out.

 

[ThinAirDesign]

Good luck and I will check back from time to time to see if anyone has gotten off of their lazy butts and posted up some videos!

Hey Physics ... if you're out and are not inclined to answer the above, I understand.

Just wanted to thank you for the exchange --- it was fun.

JB

 

[spork]

FWIW, Your vector diagram has convinced me you are right (I think)

That's the most exciting thing I've heard all day. Until now all I've gotten is that my vector diagram is completely wrong in every way - or people refusing to acknowledge it's existence -right or wrong.

But also the vector diagram would also show an ice-boat can not go DDWFTTW, whereas the 'wind trolley' can? D

That's absolutely right.

Because the source of power isn't the wind but the difference between wind speed and ground speed, which is independent of vehicle speed.

I continue to be impressed. It's clear that you understand the concepts and are open minded to the possibility. I'm very nearly certain you'll become a believer.

And my answer is that I don't know for sure. Here is where I'm at:

1. The iceboaters of the planet certainly claim that a VMG downwind is a piece of cake. There's lots of them and only one of me so I'm inclined to follow along.
2. It would seem that you could take all the principles of the iceboats and squeeze them into a cart with rotating sails and the kinematic constraints of wheels to build a cart that will go DDWFTTW.
3. Jack Goodman claims to have built such a cart and posted the Youtube video which gets me excited but is hard to accept for documented evidence as "proof possible" since what we could be witnessing are artifacts of the experiment and like all good experiments really needs independent confirmation.
4. When I try to reduce it all down into an environment that would reduce the possibility of any such artifacts and would be much easier to test, control and document (the cart on a treadmill), I run into the issues I stated on my first post.

It is certainly a quandary.

And that to me is VERY refreshing.

You and I were having a nice exchange, Jeff and I were having a nice exchange. Nevertheless here we are with the betting.

I really only asked simple questions and expected only simple answers but the only one who would do so is you and Jeff.

Well I'm sorry it seems that way. I have tried to answer all questions. The bet is only offered to people that are NOT asking questions - people that are sure they already know the answer.

Why? How confident someone is on his/her position is irrelevant to this entire discussion. I know someone who was confident enough that the Patriots would win the Super Bowl that they dropped 25 large on it.

You have it exactly backward. How much you bet isn't what makes you confident or right. How confident you are governs how much you'll bet. People are insisting they're absolutely right - and that others are absolutely wrong; but clearly they're not as confident as they claim to be.

Here is one thing I will leave you with:
I have now gone full circle on this. I originally argued that it was a "no-way no-how" thing.

And there we are. You didn't come on asking simple questions and wanting simple answers. You came on here ignoring all evidence and telling us we didn't understand physics.

Then as it turned out to be possible with land yachts and iceboaters I could only believe that it's certainly possible to collapse it down to a cart heading directly downwind. When I saw Jack Goodman's video I thought "holy cow I got to build me one of those!"

And all that is great. It proves you were in fact far more open minded than you let on. Don't get too upset if we took you at your word when you said "no way - no how".

Not only did I fail, I wasn't even in the ballpark.

Low drag and efficiency is key. Jack went to a lot of effort reducing drag and making an efficient prop.

The beauty of it all is that this only proves that I don't know how to build a cart that will make forward progress on the treadmill. I'll be the first to admit it. Whether it means that it is impossible to do or that I just suck at it I don't know. That is what is so cool about the whole deal - you can never disprove it but it may be possible to prove it can be done.

I'm glad to hear you say that.

 

[rcgldr]

So here's mine:

Well a heli rotor is designed for high speed, high lift, and has a lot of drag. You need a better propellor, one that can generate around 5 mph of air speed efficiently. I see 3 issues. Losses in the drive train, propeller efficiency with the induced wash issue, and most importantly, if the apparent wind on the blades or a propellor is really different than the apparent wind on the cart.

Drive train: in general, chain or belt drives are more efficient than geared drives.

Propeller - one similar to the Gossamer Albatross, but slower speed still (the Albatross flew at about 18mph), or similar to one of those rubber powered indoor models.

http://en.wikipedia.org/wiki/Gossamer_Albatross

 

[PhysicsAddict]

And there we are. You didn't come on asking simple questions and wanting simple answers. You came on here ignoring all evidence and telling us we didn't understand physics.

Not at all. You read my last post. You know where I stand on iceboats etc. I dropped in, restated the problem from a different angle so I could reduce it to the simplest of questions, then I started asking those very simple questions. Questions that if were met with simple answers would have helped me find my "kink". Questions that would be no different than I would pose to one of my engineers that came into my office with a design in order to have them defend it and help me understand it.

Low drag and efficiency is key. Jack went to a lot of effort reducing drag and making an efficient prop.

I was really shooting for that when I built a set of blades like his using balsa. Maybe fanned out balsa just doesn't scale down too well. Mine didn't even work as good as some of the heli blades. Any Ideas?

Well a heli rotor is designed for high speed, high lift, and has a lot of drag. You need a better propeller, one that can generate around 5 mph of air speed efficiently...

Thanks Jeff. As I mentioned, I did try to copy Jack's blades but that is where I may have snagged. I don't have accurate specs on Jacks blades or even a side-on shot of them to go from. I was just shooting from the hip on those. I was counting on the variable pitch system to cover the bases there. In that original video I also had the cart geared wrong compared to Jack's specs. That's why I rebuilt the cart later.

As for belt vs. gears, when it comes to smaller mechanics, the gears win. I have the components to re-make it using belt drive but I assure you this is far smoother and it almost seems frictionless.

AND if nobody is going to get up and get to carving then please post up a better shot of Jacks blades - a side on shot would be great. Dimensioned drawings would be awesome (Spork? can you get him to send you this info?). When I get back and if no one has made a move toward building their own cart then I will take another run at it if I can copy those blades. In fact, anyone building their own cart is going to need this info.

Thanks guys!

Later!

 

[PhysicsAddict]

Hey Physics ... if you're out and are not inclined to answer the above, I understand.

Just wanted to thank you for the exchange --- it was fun.

JB

Oh and Ditto! I enjoyed it! I'll be around I promise.

 

[spork]

Well a heli rotor is designed for high speed, high lift, and has a lot of drag. You need a better propellor, one that can generate around 5 mph of air speed efficiently.

Incidentally, all my heli blades have symmetrical airfoils. I assume yours does too. That would certainly cost you something. Also, heli blades have no twist. Jack's cart used a blade with "true pitch". That's probably fairly important.

Drive train: in general, chain or belt drives are more efficient than geared drives.

On Jack's cart the drive belt is as loose as he can use it. Also, the pulley's are exactly aligned on the tight side of the belt.

Spork? can you get him to send you this info?

I have most of the info. But how about I get you two in direct contact? He's a very easy guy to talk to.


Incidentally, I'm curious... are most of us believing at least that the ice-boats can and do achieve downwind tacks such that their downwind velocity component is faster than the wind? The cart is intriguing for sure, but I'm wondering if people still differ on the more basic "building block" to this brain teaser of sorts.

 

[Topher925]

Physics Addict,

So here's mine:
http://s167.photobucket.com/albums/u123/DarwinAward/

Great work! I just only wish I had time to finish up my theoretical analysis of this so we could compare it to your experiment and see if they verify each other. Unfortunately, these thermo labs won't grade themselves.

Also, try to keep this thread strictly based on the physical aspects of this device. Comments such as "take the bet" and "nasla says it can happen" are not valid arguments and don't prove or support anything. As I stated on spork's original thread, if posts using non-valid or irrelevant evidence or arguments are used to support your claim then they will be ignored by me and hopefully by all others as well.

 

[ThinAirDesign]

Comments such as "take the bet" and "nasla says it can happen" are not valid arguments and don't prove or support anything. As I stated on spork's original thread, if posts using non-valid or irrelevant evidence or arguments are used to support your claim then they will be ignored by me and hopefully by all others as well.

There is no better "analysis check" than the real world. If your analysis says that the balloon will win every time and the guys racing the NALSA races are beating the balloon every time, it's a pretty fair sign that your "analysis" is wrong.

Ignore the real world at your own peril.

JB

 

[OmCheeto]

There is no better "analysis check" than the real world. If your analysis says that the balloon will win every time and the guys racing the NALSA races are beating the balloon every time, it's a pretty fair sign that your "analysis" is wrong.

Ignore the real world at your own peril.

JB

I'm going to ignore the comments over the last 12 hours because I don't have time for 5 pages of nonsense, along with the fact that I figured it out last night, approaching sleep.

It's a similar effect to either roller skating or swinging on a swing.

Neither roller skates or swings have motors. But the devices in question just seemingly keep on going faster and faster.

It's the energy added by the RC steering mechanism that imparts the seemingly impossible forward thrust to the device.

And do not ask me for force vector diagrams... It's so second year university...

 

[ThinAirDesign]

It's the energy added by the RC steering mechanism that imparts the seemingly impossible forward thrust to the device.

Yes, you finally hit on the well known fact that if you jerk the front wheel of a tricycle back and forth with the right timing, a minicule amount of force can be amplified to astounding speeds unknown.

Brilliant.

JB

 

[Topher925]

Yes, you finally hit on the well known fact that if you jerk the front wheel of a tricycle back and forth with the right timing, a minicule amount of force can be amplified to astounding speeds unknown.

Brilliant.

JB

ThinAir, while I do still disagree with you I do have to admit that I did "lol" a little bit when I read your last post.

 

[spork]

And do not ask me for force vector diagrams...

No need to ask you for any force vector diagrams since I already derived, posted, and explained them in detail. What I just can't understand is how anyone could possibly deny this when such a trivial analysis shows it's completely doable.

If it's so "second year university" why can you not point out the flaw in my diagram?


So the evidence now exists in the form of a simple analysis, GPS data plots, the direct quotes from those that perform this "feat" regularly, and a video showing it in real-time. Not believing this is a lot like not believing we sent man to the moon, or that the 9-11 attacks were a U.S. government conspiracy. There's simply a landslide of information that this happens all the time, and no evidence to the contrary - but people have it all figured out I guess.

 

[spork]

I'm just completely baffled that people don't follow this. Forget about ice-boats tacking downwind (in fact it appears that everyone has conveniently forgotten that). Can we agree that a sailboat can tack upwind? If so - we're done. It's EXACTLY the same thing.

Now my bet is that no one will respond to whether a sailboat can tack upwind. People seem to like to ignore the simple hard evidence.

 

[Topher925]

Can we agree that a sailboat can tack upwind? If so - we're done. It's EXACTLY the same thing.

Of course a sailboat can tack upwind. But NO it is not exactly the same thing. If you actually believe it is the same thing then your logic is seriously flawed. This is not so much a matter of relativity but a matter of kinetic energy and how it is being transferred. The fact that you would even make a statement such as that demonstrates that you do not comprehend the phenomenon you are trying to convey.

As for your vector diagrams, is this the only one that you have made?

http://www.putfile.com/pic/8419299

I have ignored it because its a very poor diagram and really does nothing to model or demonstrate the subject at hand. I would like to see you create a diagram that has a summation of the forces inflicted on the boat assuming its sail is an actual airfoil as ThinAirDesign has suggested. I found that there are 5 significant force components acting on the boat and can be modeled as functions of velocity in the x and y directions an the velocity of the wind. The drag, lift, and wind force coefficients should be the only variables that define the system. Consider them as the eigenvalues or eigenvectors of the system. I used lift and drag coefficients for a NACA 0012 airfoil, perhaps thin air design can give me a more practical airfoil to reference.

 

[spork]

Of course a sailboat can tack upwind.

Well then we should be all done here - since all of us on the physics forum understand how inertial reference frames work.

But NO it is not exactly the same thing.

D'OH! It seems I spoke too soon. Are you actually telling me there's a difference between a boat in calm water with a 5 knot wind vs. a boat in calm wind and a 5 knot current? What if you were in the middle of the ocean with no GPS? How could you possibly tell the difference?

The fact that you would even make a statement such as that demonstrates that you do not comprehend the phenomenon you are trying to convey.

You're embarrassing yourself.

I have ignored it because its a very poor diagram and really does nothing to model or demonstrate the subject at hand.

Yes, you've demonstrated already that you don't understand my completely accurate vector diagram. Although you haven't been able to point out any specific problem with it.

I would like to see you create a diagram that has a summation of the forces inflicted on the boat assuming its sail is an actual airfoil as ThinAirDesign has suggested.

First of all, my diagram does exactly that. Secondly, ThinAir never made any such suggestion.

[lots of nonsense]... perhaps thin air design can give me a more practical airfoil to reference.

Of course - why trust someone with an M.S. in aero on something this simple?