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Mess with your minds: A wind powered craft going faster than a tail wind speed.

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Kleinstein:

--- Quote from: electrodacus on September 18, 2021, 07:05:25 am ---
If for some reason you want to look at this system from a modified frame of reference and switch the vehicle characteristics with ground and then continue the experiment from there then you need to look at now moving ground kinetic energy to know what happens with vehicle speed.
I do not get why people will want to change reference frame and deal with all the complexities of that (seems people wrongly think changing reference frame has no implications and then get to wrong conclusions).


--- End quote ---
The change of reference frame is helpfull. If one understands how to do it, it is a realtively simple step - though it can confuse others.

An obvious point with the change of reference frame is that the movement would be the same independent from the reference frame. So if you look at it with the fixed ground as reference and you accept that the vehicle moves to the right this means that with the pater as the reference from the vehicle will more faster than the driving system (the ground).  When looking at kinetic energies the change of reference frame can be a bit complicated. When looking at force it is not at all complicated. When your argument has a problem with the change of refrence frame and gives different results (e.g. violation of conservation of energy in one frame but OK in the other) than this shows a problem in your "theory" understanding.

The change of reference frame is mainly needed to understand the experiment with the vehicle on the treadmill.  The same step is than used for the wheeled vehicle on the treadmill. So the slow wheeled vehicle is a direct analog to the prop driven vehicle on the treadmill.

Brumby:
I had a look at your video and I can see where your argument is based - however it is nowhere near an accurate representation of the Blackbird mechanism.  The best I can say is that it is somewhat backwards and that this claim:

--- Quote from: electrodacus on September 17, 2021, 07:20:27 pm ---You can see the effect of how blackbird works in my slow down video version.

--- End quote ---
is completely invalid.  You presume your presentation models the Blackbird mechanism - which it clearly does not.

If you want to insist on there being some form of energy storage, then the only quarter I will give in that direction is that there is energy in the wind.

Nevertheless, all our arguments have been, are and will continue to be in vain if you persist with this generator/motor wheels topology.  The key elements here are the wheels, the propeller and the driveline between them in a windy environment.

Those elements have been explored in two frames of reference, which have both shown the effect is real.  These frames of reference are:
 1. with respect to the ground, where the vehicle is in motion, as is the air (wind)
 2. with respect to the vehicle, where only the ground is in motion and the air is still
In both frames, the wheels are rotating and the propeller is spinning


Your generator/motor wheels topology is not appropriate - yet you continue to insist that it is.  The problem is that you cannot (or will not) consider it might not be correct ... and it is this stubbornness that will see you consistently mislead yourself.

Alex Eisenhut:
Jesus Christ! STILL can't spell BRAKING correctly?  |O

Look, the spinning propeller creates a virtual sail behind the vehicle. It pushes against the wind, if you sum the velocities you end up with 0, but since it's blowing backwards, it adds to the ground velocity of the vehicle.

You can view this virtual sail as storing the initial energy of the vehicle being blown from rest to its cruising velocity.

iMo:
"Flywheel storage" - that is a concept which works.
Why the rotating propeller and rotating wheels cannot be considered (in the Blackbird's case) an "energy storage"?
https://en.wikipedia.org/wiki/Flywheel_energy_storage

electrodacus:

--- Quote from: imo on September 18, 2021, 04:01:21 pm ---"Flywheel storage" - that is a concept which works.
Why the rotating propeller and rotating wheels cannot be considered (in the Blackbird's case) an "energy storage"?
https://en.wikipedia.org/wiki/Flywheel_energy_storage

--- End quote ---

They are an energy storage and spinning propeller due to much larger weight and diameter stores significantly more energy that all wheels combined so usually I do not mention the wheels.
But this energy storage can not by itself accelerate the vehicle above wind speed that is why it was ignored even if I'm sure they considered that.
To be more precise the propeller flywheel storage effect is not useful if blade pitch is fixed but it is not so that is another mistake they made allowing variable blade pitch.
Still even vehicle with no variable blade pitch like the small treadmill model shows it can exceed wind speed meaning that another energy source is responsible for exceeding wind speed and that is pressure differential energy storage.
Seems pressure differential energy storage is less known as it is a very different type of energy storage and less useful.  Perfect equivalent for pressure differential energy storage is an inductor and also not many people see the inductor as a useful energy storage device compared to a capacitor that will be perfect analog of a flywheel.
The difference is that in a capacitor same as in a flywheel you can store energy longer therm with minimal losses while in an inductor and pressure differential you need to maintain a current to keep the stored energy else if you stop the energy gets dissipated super fast so no long therm storage is possible like with a capacitor / flywheel.
Same as amount of energy is very significant with a large flywheel (like the one on blackbird) vs a typical electrolytic capacitor there is a large difference in storage capacity between a typical inductor and the pressure differential created by blackbird propeller.
So blackbird electrical circuit equivalent is made of a large inductor and two capacitors (pressure differential and flywheel + vehicle kinetic energy).
While the pressure differential discharges it charges the flywheel and vehicle kinetic energy that is proportional with vehicle speed.
There is also a resistor in circuit representing the friction losses so the inductor (pressure differential) that is charged in the initial acceleration phase (vehicle well below wind speed) is then discharged and that energy charges the two capacitors and some smaller part is lost in the resistor (representing friction).

Not sure is you have enough electrical knowledge to find the analogy useful but someone here most likely has that knowledge.

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