Ripstick + Depleted Uranium

[cantunamunch]

As an experiment I got some carbon skis (Fischer Hannibal 106, 186, ~1740 g per ski) with lightweight bindings (Shift) and mounted a 280 g mass on each tip: hockey training pucks, heavier than normal pucks. I've had them out in three heavy Baker powder days so far. They are a total blast. Light underfoot, easy to pivot and bang out turns, yet still very stable through chop, much more so than my Ranger 102FRs. The only weird thing is picking them up in the parking lot. With the center of mass shifted forward, it makes them a little awkward to carry.

If you're up for it, try sandwiching some Sorbothane between the puck and the topsheet. Softer than the puck so ~ 40 OO is probably a good durometer to start.

 

[Noodler]

If you're up for it, try sandwiching some Sorbothane between the puck and the topsheet. Softer than the puck so ~ 40 OO is probably a good durometer to start.

I was intrigued by this idea, but the hockey training puck just strikes me as being way more weight than I would want to go with. So you could actually "kill 2 birds with 1 stone" by using the Isolate It brand of Sorbothane vibration accessories available on Amazon. They have some 1/2" thick 2.25" diameter "pucks" of the stuff (they're 30 durometer).

 

[cantunamunch]

I was intrigued by this idea, but the hockey training puck just strikes me as being way more weight than I would want to go with.

OP's system is still a one mass system - it works by changing the resonance of the tip and tip spacer relative to the body of the ski. My tweak sets up a reasonable approximation to a two-mass system.

This

They have some 1/2" thick 2.25" diameter "pucks" of the stuff (they're 30 durometer).

sets up a distributed low-mass system. AKA a one dimensional whip, with all the accordion jiggling that implies. Honestly, no idea how well it would - or not- work.

If low mass is a driving parameter, CLD is a far better solution - but then you need a top plate and both sides need to be adhered with an adhesive that supports shear modes (i.e. epoxy and acrylic ought to work but silicone adhesive will not).

I don't think OP wants a Rossi style VAS, he seems to enjoy the skiability of the mass tuning.

 

[Noodler]

OP's system is still a one mass system - it works by changing the resonance of the tip and tip spacer relative to the body of the ski. My tweak sets up a reasonable approximation to a two-mass system.

This



sets up a distributed low-mass system. AKA a one dimensional whip, with all the accordion jiggling that implies. Honestly, no idea how well it would - or not- work.

If low mass is a driving parameter, CLD is a far better solution - but then you need a top plate and both sides need to be adhered with an adhesive that supports shear modes (i.e. epoxy and acrylic ought to work but silicone adhesive will not).

I don't think OP wants a Rossi style VAS, he seems to enjoy the skiability of the mass tuning.

Good points. So is the FLOshocks system a 2 mass system or something more complex in action with that solution?

 

[cantunamunch]

Good points. So is the FLOshocks system a 2 mass system or something more complex in action with that solution?

Ooof, I'm not even going to attempt to describe that with english words - the only thing that simplifies that design is that it has a limited number of attachment points to the ski.

 

[Ecimmortal]

If you're up for it, try sandwiching some Sorbothane between the puck and the topsheet. Softer than the puck so ~ 40 OO is probably a good durometer to start.

So a tuned mass damper?

 

[cantunamunch]

So a tuned mass damper?

If there was a top flex element in between the puck and the screw/washer, then it would be, yes - like an old Dynastar chicken heart.

 

[tomahawkins]

I don't think OP wants a Rossi style VAS, he seems to enjoy the skiability of the mass tuning.

My main goal was just to improve yaw stability, i.e. less twitchyness in chop, not necessarily vibration attenuation. I suspect a fixed mass would be better for this. However, I like the idea of floating the mass on Sorbothane. I'm thinking about having the mass ride on a shaft and then suspending the mass above and below with two layers of Sorbothane. Then the system is mostly rigid in the lateral (yaw) direction, but is a suspended two mass system vertically. I suppose this is more or less a chicken heart.

Out for another day at Baker yesterday. As @Posaune can attest, conditions were pretty good. The skis were great in the soft crud up top, harder down below where it turned into semi-refrozen clumps. Next time out I may try an A-B test where I keep the puck on one ski and remove it from the other.

 

[cantunamunch]

My main goal was just to improve yaw stability, i.e. less twitchyness in chop, not necessarily vibration attenuation. I suspect a fixed mass would be better for this. However, I like the idea of floating the mass on Sorbothane. I'm thinking about having the mass ride on a shaft and then suspending the mass above and below with two layers of Sorbothane. Then the system is mostly rigid in the lateral (yaw) direction, but is a suspended two mass system vertically. I suppose this is more or less a chicken heart.

Pics when you get to it. Especially if you dimple the top washer against rotation.

 

[cantunamunch]

I was intrigued by this idea, but the hockey training puck just strikes me as being way more weight than I would want to go with. So you could actually "kill 2 birds with 1 stone" by using

Pop onto amazon and search for Happy Ball / Sad Ball. The sad ball is a polynorbornene rubber that gets *better* at absorbing energy the colder it gets. Just keep it away from oil.