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Search found 2214 matches

by gordonjudd
Mon Jan 21, 2013 3:27 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

Do I really have to quote every time? Vince, If it bothers you that I added: I certainly did not understand it when Grunde first presented it several years ago. (notice the itallics) to my original post to indicate that unless you think in terms of integrating differential equations in your head, M...
by gordonjudd
Mon Jan 21, 2013 2:06 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

I think there is general agreement that the rod is 3rd class lever, Vince, I think that we can agree that the broomstick functions as a third class lever, but because of the more complicated dynamic response of the spring in the rod to external forcing accelerations the rod (even to first order) do...
by gordonjudd
Sun Jan 20, 2013 9:29 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

Did you mean the brick will take off at maximum car velocity? and Yes Walter, thanks for correcting me Merlin, Shouldn't that be the maximum spring velocity?  As I remember the maximum car velocity was around 16 m/s for the Paradigm cast while the maximum spring (and hence brick velocity) was aroun...
by gordonjudd
Fri Jan 18, 2013 2:18 am
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

- - Grunde's model: The mechanical advantage of the bendy rod is because it allows the caster to input more energy for the same stroke length, arc and acceleration/speed history. Merlin's model: The mechanical advantage of the bendy rod is due to its more efficient use of the same energy input. Ait...
by gordonjudd
Fri Jan 18, 2013 1:50 am
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

...I do not have any different privileges in regards to the time allowed to make edits to a post on this forum than you do and As a moderator I think you do Gordy. Maybe you could put your edits in another colour, or as italics? Magnus, As a general moderator you may have editing privileges on all ...
by gordonjudd
Thu Jan 17, 2013 9:28 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

The reason is that its "springness" makes it a more energy efficient machine; it allows for less losses. Right? Aitor, That is the idea.  If you look at the final  KE/PE ratio of the brick when it is accelerated via the spring it will have a higher ratio than when it is accelerated via a direct con...
by gordonjudd
Thu Jan 17, 2013 8:59 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

In this instance, you posted, Aitor posted and then you posted whilst managing to quote Aitor's following post Vince, Here is the complete statement from Aitor's post (#246) that I used my quote in Post #248.  I am not clairvoyant. In the same way, if we make a small trebuchet as a casting robot fo...
by gordonjudd
Thu Jan 17, 2013 8:49 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

F1(t)=F2(t)=F3(t)=F4(t) and so in the brick's view there is no difference if there is a spring or not. Sakke, F1(t)=F2(t) and F3(t)=F4(t)  in your drawing, but F2(t) will not equal to F3(t) in the case of the spring.  That is what Merlin's model is all about.  It takes solving the 2nd order differe...
by gordonjudd
Thu Jan 17, 2013 8:11 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

My remark was because Aitor had responded to Gordys post,  then an hour later Gordy changed his post. and Maybe I'll come back and change this post every time someone adds another post... Vince and Walter, I know that editing a post to make it more instructive or complete bothers you greatly, but I...
by gordonjudd
Thu Jan 17, 2013 4:15 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

But of two identical weights hanging at the same height none of them can apply more force than the other one, both have the same potential energy and can not deliver more energy than that. Aitor, That is the basic constraint of experiment you posed.  The initial PE is the same in both cases, so it ...
by gordonjudd
Wed Jan 16, 2013 11:50 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

This is very interesting. Do you think that this result applies to a real rod? Aitor, Yes.  Using the same driving acceleration and deceleration driving functions that came from Grunde's Paradigm cast measurements with a rigid rod and a flexible one there was an even bigger difference in the calcul...
by gordonjudd
Wed Jan 16, 2013 5:56 am
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

Those aren't my values but those which Merlin has chosen (by the way, the smallest mass is only 0,005 kg) Aitor, It did not have a big effect as the shape of the velocity curves are very similar, but I used your mass values for my plot, i.e.: Let's say I have a weight A weighing 10 g, and a weight ...
by gordonjudd
Wed Jan 16, 2013 2:17 am
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

I see in the distance vs. time graph that when both bricks stop at t= 1.6 Aitor, I think that 1.6 second value is the point where Merlin stopped his calculations not where the brick came to a stop in those two cases.   Since there are no losses, they would continue to travel with the maximum veloci...
by gordonjudd
Tue Jan 15, 2013 6:21 pm
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

No. I first need to design and build the device. Aitor, Determining the optimum spring constant is something Merlin should be able to work out, but finding a spring with that value might not be so easy.  You can probably live with friction effects although putting the  brick mass on wheels might ma...
by gordonjudd
Tue Jan 15, 2013 9:27 am
Forum: Flycasting - 2 Handed
Topic: Rod Loading - Spring v Lever
Replies: 602
Views: 107503

I shall post the graphic this evening. Merlin, I just picked up on this thread and am getting confused about parameters.  Your drawing will go a long way to making this more understandable. What were the masses of the brick and lead in your model?  What was the spring constant of the spring?  What ...