jim_mich wrote:Pequaide, your last post seems to be mostly a discussion of semantics. It is a discussion about what to call or name things. This is good! When someone says something and another person hearing/reading it envisions something different then it is very hard to communicate effectively.
Transfer is a much better descriptive word to use than impact. You are transferring momentum from object to object. Then you object to the word 'transmission'. I think this is because you envision a transmission as being some type of gearing device like in an automobile. The truth is a transmission is ANY device that transmits or transfers force from one object to another object. Thus if you have an overbalanced mass accelerating both the vertical wheel and the attached horizontal wheel then you are using a form of transmission.
I'm still a little confused as to exactly what you are proposing. You talk of a vertical wheel and a horizontal wheel. Was Bessler's wheel a vertical wheel or a horizontal wheel? It had a horizontal axle shaft so I guess it was a horizontal wheel? But any weights inside the wheel would have fallen vertically. So I guess it was a vertical wheel. But wait, it definitely wasn't both vertical and horizontal. So you see the verbal problem with describing any wheel or experiments? The one doing the describing thinks he is being perfectly clear, because he totally understands what it is he is trying to say. The listener/reader many times gets a totally different picture in mind. This is why a picture or drawing is worth a thousand words!
Let me explain your three steps as best I understand them...
First the setup:
Two wheels are rotationally connected. The first wheel has a horizontal axle [the vertical wheel] and the second wheel has a vertical axle [the horizontal wheel]. The first wheel has a cord wrapped around its perimeter. The cord has a weight attached. This weight can fall thus turning the wheel. The rotational connection causes the second wheel to rotate. Wrapped around the perimeter of this second wheel is a different cord. On the end of this cord is a weight that is initially latched to the wheel. When released from the wheel this second weight flies outward due to centrifugal force causing the cord to unwrap. This flings the released weight to a faster speed.
Step 1:
The weight on the first wheel (with the horizontal axle) falls a certain distance due to gravity thus rotating the first wheel and the second wheel and the weight on the second wheel. This would be the acceleration phase.
Step 2:
The weight on the end of the cord of the second wheel is let loose. The cord uncoils, which decelerates both wheels while accelerating the weight out horizontally. The released weight is sped up as the momentum transfers from the two wheels to the released weight of the second wheel.
Step 3:
This step any engineer worth his salt can supposedly do. Supposedly the second weight is flung out at such a speed that its inertial kinetic energy can lift the first weight back up to the place of beginning thus re-wrapping the first cord. Also the second weight must be moved back towards the wheel while re-wrapping the second cord. Supposedly this can all be done using only the energy of the fast moving second weight.
Did I correctly understand the basic steps and setup? Probably not! I probably screwed up something or misunderstood something. That is why diagrams and sketches are helpful. Photographs are often confusing. Even diagrams and sketches can be confusing.
pequiade wrote:Jim; you have the concept, correct.
Springs used to wrap cords (etc.) is fine, just don't use them to store the motion of the system.
pequiade .. clarification please.
Q. Step 2: a horizontal wheel with a cord & a single weight ? - this was the puck on an air table experiment ? - IINM that's why broli went to a horizontal wheel with rigid arms that unfolded, so you avoided the air table - additionally any free weight on a cord would slump down beneath the height of the horizontal wheel unless the rpm were particularly high with high Cf's or there were guide channels & rolling weights etc - in broli's model there were two weights at the end of two arms, not a single weight & cord - it also allowed for symmetry - which is correct, single weight & cord or two ? - either way broli's rigid horizontal unfolding arm version doesn't have any gravity component while a weight on a cord that slumps must be lifted as well as wound in adding an extra complication it would seem.
I am unfamiliar with constant force springs; I know regular springs store energy not momentum and they will not work. . How efficient are constant force springs? Gravity is 100% efficient. A pendulum bob will swing for several hundred cycles can a constant force spring do that. How much do they cost? Why use them; are we short of overhead space that we can’t use gravity. Ya; flinging things into the ski never bothered me, kinda fun, why do you think people like baseball and golf.
I am afraid you want to enter the failure mode broli, we know what works now you want to try something else.
Fletcher question: which is correct, single weight & cord or two
Both are correct, it is the concept that is correct. The cylinder and spheres has two masses on cords and no center bearing. The disk and pucks on the air table have two masses and no center bearing. The horizontal white disk with a bearing can throw one puck on a cord. The vertical wheel throws one mass. You can avoid the center bearing by balancing two or more unwinding masses, but the concept remains the same.
Fletcher quote: cord that slumps -- an extra complication
Yes; but broli’s arms have mass. We have to recover the motion of the arms, doable but another complication. The fishing line cords have very little mass, and are suitable for experimentation.
Failure mode? I'm just suggestion what I believe to be sound ideas. Besides the mass issue I don't see what's wrong with using stiff arms. It keeps things simple and easy to experiment with. I went through most of your posts the other day and understood things I didn't understand back then. But the strange thing is that nowhere do I see speed data of initial and final conditions. I wonder why that is.
The design I proposed allows for simple speed measurement and can then be transformed into a practical power generator unlike your ramps and 1 ton carts. You propose slow and heavy, big setups. I propose fast and light, small setups. How far in your current setup does your mass on your atwood have to drop to produce an initial rotation of 3000 RPM? And how far up does it have to go after the transfer? I assume km's. That's not practical if you want to produce lots of energy on a small scale. That's why a home setup would use a motor and a generator to input and output energy. You can input 10 000 joules for instance and get 100.000 joules back on a relative small scale, unlike your 50 ton setup.
The constant spring idea was just an experimentation suggestion to allow for high rpm's without having to drop some 1kg mass from a building. Using a tape meter would even double as a measuring tool to compare how much the same meter gets rolled up after momentum transfer.
pequaide wrote:
Fletcher quote: cord that slumps -- an extra complication
Yes; but broli’s arms have mass. We have to recover the motion of the arms, doable but another complication. The fishing line cords have very little mass, and are suitable for experimentation.
The solution is that the extendable arms can be made from light weight carbon fibre for example or some plastic truss arrangement to keep weight & mass down to a minimum.
If however you are concerned about their mass affecting the results then they can be almost engineered out by having a weight on a beam that folds out [as broli does] - but the beam has equal length, volume & mass each side of the pivot i.e. centrally pivoted - alternatively a small counterweight can be added to the arm on the opposite side of the current pivot position & this balances the mass but gives slightly more inertia as in both cases - this shouldn't affect the final velocities too much though the extra inertia would be a slightly less efficient system than broli's original end pivoted arm, IMO.
At some point the system must be retracted & rigid arms is probably easier [spring loaded cogs or cam] than winding up nylon fishing line because you probably have to use a coil spring & rotor - both require some energy from the system.
Thanks Pequaide for explaining your choices of words. Apologies if I was not using my words clearly.
Can we have a slow impact - AFAIK, yes. I was thinking of Impact in the form of a physics Impulse. Agreed - a Transfer of Momentum is less confusing.
As Jim said - a picture is worth a thousand words, because it's very possible to get concepts wrong. This is a long thread, over many months, and I don't remember everything clearly - even if there have been pictures before.
I believe I understand and agree with what you are saying. I expect if we could all see what you have seen firsthand, there wouldn't be any disagreement.
It would be nice if we could turn this into any easily replicable experiment that removes all doubt - I think we can't be too far away now.
When Bessler said he used a spring, but not in the manner of a wind-up energy storage - maybe he was refering to a cable re-wind mechanism?
Maybe he achieved his results in less than 360 degrees of rotation, so maybe it was as extensive as the taperule/lawnmower pull start/vacuum cleaner cable tidy arrangement, but still a 'rewind' or sorts ...?
(Not meaning to confuse the issue with words - just wondering where his spring fits into all this ...)
I can accept that springs are too lossy - and the quick Jerk of a bouncing steel ball or cable is probably more like the ideal elastic effect that we need ...
