My original follow-up post attempts to this thread were nuked by the EpicEditor. Guess it randomly censors input. Oh well. Maybe it needed re-write anyway…
On the comment by SSH regarding ‘Outside Force’: I think placement of Muscular Force
should be in the realm of Internal Force
rather than Outside Force
Any muscular force we create while skiing is Internal to the System we’re trying to analyze. Internal Forces can only affect the system studied (with respect to the outside world) in terms of orientation (like a cat’s ability to ‘right itself’ in midair - a very real example).
An Internal Force can't affect its External surroundings unless that force is somehow translated/transferred into an External Force. In skiing we do this transfer via collisions
- like when we extend a Leg - Which extends our ski; which then smacks into the snow (a collision). Even air friction slowing us down is a collision - or rather many
collisions with gobs and gobs of air molecules.
On the debate between WTFH & Ghost: It’s not so much Apples and Oranges
I see them debating as it is Oranges and Orangutans
. Both seem ‘right’ and I suspect both know exactly
what the other is saying - each was just fishing for acquiescence from the other, right?
On the bike thing: As mentioned above Internal Muscular forces of the System interact with the outside world via collisions. The bicyclist pushing/pulling on a pedal (gotta remember those toe-straps) transfers mechanical energy to the pedal: Which transfers mechanical energy to the chain; Then to the hub sprocket; To the spokes; To the rim; To the tire rubber - where mechanical movement of the rubber collides with the road surface, driving the cyclist ahead.
Originally Posted by Si
The circumstances under which the ski shovel can be selectively bent further via steering without producing some level of release at the tail are still unclear.
Google up Collisions
and try to find a page dedicated to explaining the nature of elastic vs. inelastic collisions. In many ways this whole discussion is a discussion of collisions. It’s certainly not a topic for the faint of heart but does provide great insights into all things skiing. Wish I could find a synopsis out there to link in, but haven’t the time to search for a good one.
Originally Posted by Si
This may also relate to the first question in that I suspect that as the tipping angle increases the amount of steering force that can be generated is reduced.
As the tipping angle increases the amount of Steering Force
that can be generated is *increased* (if by Steering Force
you mean the amount of centripetal force generated at the ski tip). At some degree of extreme edge-angle I’m sure it starts to decline though I’m not sure where. Not enough free time to mess with spreadsheets on it.
By the way, “Steering” by definition means: controlling the course
and nothing more. Sorta like “Redirection” in the other thread; doesn’t really convey anything meaningful about precise mechanical movements. Tipping the ski creates a ‘steering force’ all by itself.
Originally Posted by Si
The degree of confusion between "active" steering and "passive" steering remains something I wonder about. Increased tipping involves a considerable amount of hip rotation. Hip rotation can readily give the perception of an "active" steering force even when it may be producing only active tipping.
Not sure what you mean by “Passive” steering. To me, any kind of‘Steering would be Active. Park & Ride
is actually a good example of *Not Steering*. The Existing Bend in the ski continues to turn the skier on a fixed course so the skier need not add any input. No new pressure, no new tipping, no new rotation = no steering (in my view).
Some degree of Increased Tipping can be accomplished by exclusive banking with no hip rotation. We can also angulate at the hips & waist without any hip rotation (in terms of femur rotation - not sure if people count adduction/abduction as a form of hip-joint “rotation” - which it is, just in a different plane.)
Quite agree with you that many people undoubtedly use knee-angulation
rather than Independent-Leg-Steering
(another term I’m not fond of) and may well misinterpret what they’re really doing. That said I think the participants of *this thread* know exactly the difference in the mechanics applied - their textual input demonstrates it.
One more noteworthy thing to consider is rut formation
Only the tip (front) of the ski floats up as the ski moves forward. As a ski moves forward the tip climbs up on top of the snow surface. ('up' meaning relative to the surface)
As the ski continues to move forward, the snow is increasingly compressed (in all conditions - even ice). This surface-compression is maxed-out when the section of the ski underfoot passes over that point because that’s where the highest pounds-per-square-inch is (see a weight-distribution diagram of a ski). As the ski progresses still further forward the tail (having less pressure per square inch) cannot compress the snow any further - it just slides along against the bottom of the pre-existing compression.
Sometimes people envision a scenario as though the ski were on a Foam Pad
but the foam pad analogy is inappropriate as applied to skiing.
If on a foam pad, when we move our weight forward on the ski, the tail rises up. It does so because the foam is Elastic. W
ith the pressure reduced on the tail the foam is able to push the ski tail upward. The snow surface is Inelastic
and does not rise up again.
Levering forward to create more pressure on the Tip simply moves the point of highest Pounds-per-square-inch (under the ski) further forward - it doesn’t Rock the ski Forward
as it does on the foam pad nor will it pivot a ski if it’s on edge.
Of course, in Bottomless Powder
that same ski might just pivot forward 'cause we're skiing on more of a Fluid than a Surface at that point.