Live Catching - Is it possible?

[Bonzo]

Totally leaving my comfort zone here, but aren't momentum and energy two sides of the same coin according to Einstein's theory of relativity? Any MIT alumni present?

 

[Sean DonCarlos]

During a dead bounce, the ball lands on the flipper without any opposing motion, and compresses the rubber severely. The rubber then expands and imparts a small force to the ball, helping to propel it back upward.

During a live catch, the ball lands on the flipper, which is moving with just enough force that the momenta of ball and flipper cancel and the velocity of the ball is reduced to zero without overshooting. Since there is no longer any downward motion, the flipper rubber is not compressed and therefore does not spring back and impart an upward motion to the ball. The ball comes to rest on the upraised flipper.

During an on-the-fly shot, the flipper meets the ball with additional force, more than is required to merely bring the ball to rest. The flipper rubber is driven into the ball (instead of merely being in contact with the ball in a live catch), compressing it, and the resulting expansion imparts additional upward motion to the ball. This is why on-the-fly shots sometimes launch the ball much faster than a shot from a trap or fed from an inlane.

 

[Matt McIrvin]

Totally leaving my comfort zone here, but aren't momentum and energy two sides of the same coin according to Einstein's theory of relativity? Any MIT alumni present?

Yes, they're part of the same four-dimensional vector. But all four components are independently conserved (three of momentum and one of energy), which is how the Newtonian case falls out in the appropriate limit.

I personally suspect the detailed answer to my question involves the physics of the flipper solenoid coil and lever mechanism, but I'm not sure. Just saying the momenta cancel isn't a sufficient explanation, since the momenta also cancel in a head-on collision between two rubber balls where they both go bouncing away afterward.

I believe it's true that the ball pushes back on the flipper and cancels its upward motion. But why isn't it just as easy for the ball to cause a momentary downward motion in a held flipper, with the same net effect of energy absorption (transformed to a moving reference frame)? I think the magnetic forces in the latter case are actually smaller, since the higher-resistance hold coil is engaged. But somehow the held flipper acts more like an immovable rigid body.

 

[Fungi]

Fire bad. Tree pretty.

 

[Sean DonCarlos]

Fire bad. Tree pretty.

Shiny ball stop on flipper. More pretty.

 

[SKILL_SHOT]

It reminds me of THE MIGHTY DUCKS movie when the coach uses eggs to teach how to pass.

 

[xNiCeGuYx]

Played some Pro Pinball B.R.U.S.A. today and I love the flipper physics! Life catches are possible but you need skill just like in real live! Hopefully FS updates their physics soon.

 

[zaino]

I don't think the momenta cancelation make sense either. As you said, being this an elastic collision, kinetic energy must be conserved as well.

What if the flipper, being at the end of it's hinge joint limit, at the frame after contact actually bounces back from it?
Then if would be like a super quick drop catch.

What do you say?

Yes, they're part of the same four-dimensional vector. But all four components are independently conserved (three of momentum and one of energy), which is how the Newtonian case falls out in the appropriate limit.

I personally suspect the detailed answer to my question involves the physics of the flipper solenoid coil and lever mechanism, but I'm not sure. Just saying the momenta cancel isn't a sufficient explanation, since the momenta also cancel in a head-on collision between two rubber balls where they both go bouncing away afterward.

I believe it's true that the ball pushes back on the flipper and cancels its upward motion. But why isn't it just as easy for the ball to cause a momentary downward motion in a held flipper, with the same net effect of energy absorption (transformed to a moving reference frame)? I think the magnetic forces in the latter case are actually smaller, since the higher-resistance hold coil is engaged. But somehow the held flipper acts more like an immovable rigid body.

 

[zaino]

It would also explain why the flipper is moved more easily back even if the magnetic pull is stronger compared to the held up flipper: the ball is pushing it back, plus the recoil from having hit the end of the joint (which is in reality the maximum compression of the spring that the magnetic force is compressing).

 

[Matt McIrvin]

What if the flipper, being at the end of it's hinge joint limit, at the frame after contact actually bounces back from it?
Then if would be like a super quick drop catch.

I wondered about that possibility myself. I'm not sure.

It's even possible that the physical mechanics of these advanced flipper techniques hasn't been studied in sufficiently great detail. If it has, it doesn't seem to be online.

 

[zaino]

I posted the question on a physics forum: http://www.physicsforums.com/showthread.php?p=4266786&posted=1#post4266786

Anyway given the elastic nature of the flipper-ball collision, the flipper HAS to bounce back. There's no other way. And if the force that's holding it up is enough to avoid the bounce back, and the force during the motion is stronger than that, it has to vibrate ever so slightly at the apex.

 

[kimkom]

I agree with you Bonzo, having watched a lot of Kerin Bowens, I've thought a lot about what's actually going on in a live catch. I've come to the conclusion that the speeds cancel each other out. Rather like two cars hitting each other on a highway, they both come to a complete stand still, don't they!?

With a live catch, I've always had to wonder if they are actually worth the risk? Obviously the slightest timing error can throw the ball anywhere. I would have thought that there would be a safer alternative almost all of the time.

 

[Zaphod77]

Live catches work because of the EOS(end of stroke) switch on the flipper.

If the ball strikes the flipper JUST as it switches to the hold coil, you get that effect. Too soon and the ball goes fling away because it was struck by the full force of the coil. Too late and the ball bounces off because of no momentum to transfer from the flipper. The flipper must have forward momentum when the ball strikes it, and only the hold coil must be active.

Now you know the physics behind it.

 

[Sumez]

No, that was the explanation of what happens. The physics behind it would be the explanation of why it happens.

 

[Exo]

In my opinion this thread deserves a necro bump since there are still no actual live catches (or cradle separations) in the game.
It would be nice to get some official info on whether these will ever make it into the physics engine.
I can't be the only one that would love to have those in-game, right?

 

[DanBradford]

if nobody else is gonna say it, i'll just point out that it's not Kerin Bowens, it's really not, probably i just missed the joke.

Bowen Kerins is my pinball hero, i would follow him into war, and he deserves a correct name call: Bowen Kerins won PAPA (4) in 1994 at the age of 18, he has a BS in mathematics from Stanford University and an MAT in mathematics education from Boston University. He won $1,000 for knowing the number of degrees in a right angle, on Who Wants to be a Millionaire, on his way to winning $32K. he won PAPA (8) for a second time in 2005, then he won PAPA (16) in 2013. Oh, and he won the Classics comp at PAPA 10 and PAPA 12. Look out for Bowen at PAPA 32 in 2029, he will be unbeatable.

http://pinballhead.com/bowen-kerins-talks-pinburgh-pinball-and-how-to-be-a-better-player/

 

[brakel]

Live catches are actually possible in TPA but happen extremely rarely. I've tried on many occasions to do live catches in TPA but never with any success. My wife, who does not really know what a life catch is let alone how to perform one, made a text book live catch while we were playing Whirlwind recently. Well, NOW she knows what a live catch is! She knew something unusual happened and asked me what it was. I told her that was a live catch. "Oh!" she exclaimed, "How did I do that?" I have no idea!

Anyway, it seems that if it's possible to do by accident then it should only take some tweeking to make it possible to do on purpose and skillfully.

 

[Exo]

They are already kind of in the game but they are no live catches that stop the ball dead in its tracks like they are supposed to (atleast not in any of the season 1 tables, don't own season 2 yet).
Instead it lessens the bounce off of the flipper you perform it on by a tiny amount compared to just holding the flipper up.

I agree that it should only take a minor bit of tweaking to get this to work properly as I'm assuming the game already checks the velocity of the upwards flipper momentum and the angle the ball hits it at as well as the timing of the impact.

Surprisingly enough drop catches already work which is a nice start.
Not sure if we're ever going to see cradle separations though

 

[xAzatothx]

be great if could map another button to cradle separation (micro flip)

 

[Sumez]

Not a bad idea. If the freresh rate (which is 60 times per second at max, opposed to the original hardware which is probably a lot higher, even on fliptronics tables) prevents proper "mini-flips", I'd say it's fair to have a special button for it. It might not be a perfect simulation of playing real pinball with the two classic flipper buttons, but at least it would allow the player to perform the same tricks!