How different radius of hollow affect skating? | Page 2 | Golden Skate

How different radius of hollow affect skating?

Ic3Rabbit

Former Elite, now Pro. ⛸️
Record Breaker
Joined
Jan 9, 2017
Country
Olympics
Yes, skating in itself is an interesting sport on the physics part.

Speed skaters use long straight blades, hinged at the toes to propel the stroke better, in the 400 mtr sprint, speeds of up to 70 Km/h are achieved!
Short track skaters use very thin curved blades, fixed but with high pedestals so they can really lean into those tight curves.
Hockey skaters use short thick blades, I assume to them both the rocker and radius of hollow are very important due to the manoeuvrability needed while battling it out in a match
Figure skaters also use short thick blades, but theirs can be thinner than hockey skaters since there is less wear and tear because no fighting on the ice, and the diverse disciplines have different requirements re curves and edges.

How does the actual area of contact surface differs between those branches of skating? There must a minimum contact surface area, otherwise you'd sink into the ice?
Hydroplaning is the key of skating, but has this actually been studied in great detail, i.e. is there a 'bow wave' to climb? I guess it is all very minute and any advantage/disadvantages are only marginal. But inquiring minds want to know ...

Track cycling materials, technique and mechanics have been studied very closely and affluent programs that have the means have bettered their results considerably though applied science.

Figure skating blades aren't thinner than hockey blades
 

tstop4me

Final Flight
Joined
Oct 2, 2015
Country
United-States
This is really interesting. I guess that having a thicker blade near the pick helps the spin and turns, but I wonder what is the advantage or disadvantage to have a thinner (tapered edge) or thicker blade (parabolic edges) near the heel.
Tapered blades have never made sense to me (other than giving extra bite near the front of the blade). The other advantage given in write-ups is that a tapered blade provides less drag in forward glides. I don't know whether that's true. But assuming it is true, that would mean more drag in backward glides. With the exception of spins and jumps, most forward maneuvers have counterpart backward maneuvers, so a blade should be equally adept forwards and backwards. The tapered blade is not. The parabolic blade is; e.g., if you are executing backward 3-turns, the extra bite towards the rear of the blade will help (the same way that the extra bite towards the front of the blade will help when executing forward 3-turns).
 

tstop4me

Final Flight
Joined
Oct 2, 2015
Country
United-States
How does the actual area of contact surface differs between those branches of skating? There must a minimum contact surface area, otherwise you'd sink into the ice?
<<Emphasis added.>> ??? If there were zero contact area, the blade would be floating in the air above the ice.

Hydroplaning is the key of skating, but has this actually been studied in great detail, i.e. is there a 'bow wave' to climb? I guess it is all very minute and any advantage/disadvantages are only marginal. But inquiring minds want to know ...
There is a lot unknown about the mechanism of skating (a lot of write-ups are just plain wrong). And there is still a lot unknown about the surface of ice itself. Experiments under controlled conditions have verified the existence of a microscopic quasi-liquid layer on ice. But real skating conditions are far from controlled (in particular, the ice, air, and blade temperatures are all different and variable; and the humidity above the ice surface is variable); and the edges of the blade cut into the ice, rather than glide on top of the surface. Lots of variables, little funding.
 

Edwin

СделаноВХрустальном!
Record Breaker
Joined
Jan 5, 2019
<<Emphasis added.>> ??? If there were zero contact area, the blade would be floating in the air above the ice.

There is a lot unknown about the mechanism of skating (a lot of write-ups are just plain wrong). And there is still a lot unknown about the surface of ice itself. Experiments under controlled conditions have verified the existence of a microscopic quasi-liquid layer on ice. But real skating conditions are far from controlled (in particular, the ice, air, and blade temperatures are all different and variable; and the humidity above the ice surface is variable); and the edges of the blade cut into the ice, rather than glide on top of the surface. Lots of variables, little funding.

LOL, you are right :)

Fluid dynamics and mechanics are hard. Only over the last decades significant advances have been made in creating the best surface for a solid body to glide through water. Sharks and dolphins knew this for millions of years: a sandpaper like texture on your skin surface glides better than smooth polished metal. That sandpaper skin is now applied to submarines, torpedoes and other navy weaponry. AFAIK, the USSR even invented a kind of underwater rocket (Shkval) or rather a super cavitating torpedo that could travel at 200 MpH or something over a short distance in its own bubble of exhaust gases blown from the nose of the torpedo.

Short distance skaters like those in figure skating probably don't benefit from any surface treatment of their skates' riding irons, but for those big oval speed skaters there might still be a couple of milliseconds per 100 meters be gained?
 

daniiltimin

Rinkside
Joined
Dec 7, 2015
ROH can be changed by sharpening skates. So basically, you can test it yourself by going to a skate sharpener and ask to get your skates done with the ROH, for example, 5/8’. When you’ll need sharpening next time, ask for ROH 3/8’. You’ll feel the difference for yourself and find which one you like better.

ROH 5/8’ would feel like you don’t have as much grip and control but you’ll be able to gain more speed. ROH 3/8’ would feel a lot sharper, you’ll have a lot more grip and bite but it will be harder to gain speed.

I personally prefer ROH 1/2’ which is in the middle between 5/8’ and 3/8’.
 
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