Leverage & Torque - WM2D predictive abilities - are they representative of real world ?

[WaltzCee]

Mwah, as long as some sub-conclusion basically points to the confirmation of thermodynamic laws.... Besides you already have a working PM.

hehehe

I totally agree, we first need a perpetual motion machine. Not for generating energy, but just to see how it gets simulated. Perhaps Fc is willing to donate one for a good cause :-)

Mwah

I've been looking at an evolving idea for a little while. Simulation had it spinning over 9 million rpm. It was a 4 inch disc with 8 mechanisms with weights around 1/100 of a pound.

I'm going to gear it up. I plan on a 12 foot diameter simulation with significantly more mass. I get the point of the thread is given there is a working wheel how would a simulation react to it. I get that.

Regardless of how it reacts, I intend to build it. I'm just going to simulate it first.

Results of the simulation in about a week. I would appreciate input as to what I should measure.

[Fletcher]

Well Walt .. assuming that you are using something like WM2D, and that the wheel starts from an overbalance position (i.e. has positive torque), then is released etc, it should start to revolve downwards.

Usually after the interplay of levers and mechanisms etc the wheel just acts like a pendulum - that is, it reaches a position of maximum velocity (PQ) at 6 o'cl then begins to slow down until it reverses direction and repeats the process in reverse, ad infinitum.

I usually have a large carrier wheel (of very low mass) behind any mechs to attach them to. It acts as a backboard. Just measure its velocity and perhaps graph it. You should see a steady acceleration and increase in velocity so that the whole of wheel doesn't act like a pendulum and revolves gaining velocity. It might reach a limitation where the rpm tops out.

That is a sure sign of a runner (assuming no bugs etc).

I also create an output that measures System KE. Just make any output you like, like time. Add a second row called Sys KE. In the field beside it type in Kinetic() - that will show the entire screens KE at any time. If it is increasing you have a runner (usual disclaimers apply).

To know for sure you have to also know if GPE is stable. What I mean is I could build a sim of a weight driven clock work mech that accelerates and gains in KE. The System KE would show a steady increase over time.

You might think on that information that it was a runner if the mechs were hidden. But it loses an almost imperceptible amount of GPE each revolution and you have to watch for a long time to visually pick it up.

So ultimately you have to do a comparison of Net GPE to KE to know for sure.

[Fcdriver]

When lift is less than drop, or power stroke, it is as a ratio. This means as you add weight, the power stroke gains more than the cost of lift. Adding 2.5 lbs would add to both, but only add 2.5 to the cost of lift, but add 15 lbs the the power stroke. This is because of leverage.

[ME]

I would appreciate input as to what I should measure.

To test it is to break/brake it.

With 9M rpm (perhaps now 1.5M rpm) I would first worry about the choice of material - not so much problematic in a simulation, but still you don't want to break it early.
I agree with Fletcher, graph speed (or kinetic energy, or RPM's) over time.
Then figure out what is needed to slow it down: add friction components as you go, put it on several slopes it needs to climb, or apply some Prony-brake variant.
Then (or before) figure out what force (torque) is needed to start it up: Use a counterweight at some radius, or a spring to tie it down (Hooke's Law). Perhaps it can be done for every partial rotation (a partial of 1/8th of the circumference for 8 mechanism)

Most of those tests could also be done with on a real build, so you'll have some reference to work with.

[daanopperman]

HI all
Cog and Com , one spinning bicycle wheel , hold the axle on one side , Centre of mass of wheel does not change , but centre of gravity does change . Centre of gravity is now on one side of the wheel .

Daan

[WaltzCee]

With 9M rpm (perhaps now 1.5M rpm) I would first worry about the choice of material . . .

Yes indeed.

But how is it possible for me to question wm2d and have it produce results so obviously beyond belief. I could understand a little off but those results were absurd. This can't be the same calculus we used to hit the moon.

Fletcher asked:

Leverage & Torque - wm2d predictive abilities - are they representative of real world ?

The answer is sometimes not even close. I think insane results are useful. They make me want to further investigate. I've been simulating this mechanism over the last couple of days. 10 pounds on a 12 foot diameter wheel at 60rpm isn't pinned to the rim. CF is a concern at that radius, yet it didn't seem to be a problem.

I "x'ed" some of the tools on my demo copy of wm2d and don't know how to get them back so I'm limited in how I make the sim.

Most of those tests could also be done with on a real build, so you'll have some reference to work with.

I appreciate the ideas and thank you also, Fletcher. This is going to be the first build I've done in a long time.

[WaltzCee]

HI all
Cog and Com , one spinning bicycle wheel , hold the axle on one side , Centre of mass of wheel does not change , but centre of gravity does change . Centre of gravity is now on one side of the wheel .

Daan

Hello Daan (I thought it was Dawn)

Adding energy to the wheel does change how gravity reacts with it but in a different way than a large mass experiencing a non-uniform attraction from one of its side to the other.

[Fletcher]

I "x'ed" some of the tools on my demo copy of wm2d and don't know how to get them back so I'm limited in how I make the sim.

Try going to menu View > Work space > select the icon tools you want or unclick simple. This should return the full set of tools.

Before you start a build I'd suggest that you try swapping out some parts and remaking them a different way.

For example if you are using a rigid joint to pin an object then try two Pin Joints side by side.

If it runs the same way when you have built is different ways then you can have more confidence in a real build.

Also as a quick test - gear a second wheel to your wheel. Pin a weight to the second wheel at 6 o'cl rim position. Start this weight at almost zero mass and steadily increase it. See if your sim can handle any load, or add friction to pins etc.

The simplest, quick and dirty load addition is just to turn on air friction.

World > Air Resistance > None; Medium; High

[WaltzCee]

Try going to menu View > Work space

Thank you.

[WaltzCee]

Fletcher,

You have saved me so much time with your advice. This is just a simple matter of fact. I'm beside myself. If we ever meet, I'm going to hug your neck!

The last time I x'ed tools I remembered admin passwords and I just reloaded wm2d and put them back. :) I have since forgotten them on this box and its the only copy of that simulator I have. You have been an incredible help to me. I just want you to know the meaning of the "thank you". Maybe for you it was a small thing yet for me it wasn't.

Again, thank you for the leverage.

Now I'm toying with this evolving idea. I frankly think I've unearthed the Prime mover. Also I'm a bit behind the curve I've declared. I just can't stop playing with what I'm seeing. Eventually I'll stop playing with the mechanism and see where it goes from there.

[Fletcher]

You are more than welcome. Best of luck and let's hope your Prime Mover is the real deal.

[Art]

Hi WaltzCee,

Nice to see you up and running !

As far as computer simulations are concerned I'm "challenged " ! : )

What exactly am I looking at in your Buzzin.gif ?

Is that a plot of overbalance in 360 degrees ? or Torque or position ?.

[ME]

Leverage & Torque - WM2D predictive abilities - are they representative of real world ?
...
I seldom look at Physics formulas before deducing what a real world (or sim) device may or may not do.

Predictive abilities of a physics-engine:

The video: https://youtu.be/1vwa8-wUJI0
The article: http://releases.jhu.edu/2016/08/08/

[WaltzCee]

Hello Art

What exactly am I looking at in your Buzzin.gif ?

That was the position of the center of mass of the mechanism I'm looking at. I drove it around with the motor. It reminded me of this:

http://peswiki.com/directory:buzzsaw-gravity-wheel

I'm not looking for a buzz saw but I thought it was interesting so I posted it.

[Art]

Yeah that's neat ! ,

I thought it looked a bit like a buzzsaw .

What on earth are you driving that mechanism with ? -

A wind up Spring ? ! : )