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Monday, August 20, 2007

Poll #3: Is a quintuple Axel physically possible?

I put up this question because I recalled friend telling me years ago that a quintuple Axel is not possible given human's physical limitations. This time, only 12 readers voted, with
  5 (42%) for "Yes, why not?"
  5 (42%) for "No, it is beyond human limits"
  2 (16%) asking "What is a quintuple Axel?!?!"

Well, I thought that in the last two weeks I could learn and understand enough about physics and bio-mechanics to calculate why it is not possible. However, I didn't manage to do come up with a rigorous proof either way, but did come across interesting articles and a train of thought:

Oh yes, first, what is a quintuple Axel?!?! I had put up an earlier post, "What is an Axel?". Well, a quintuple Axel is an Axel with 5 1/2 revolutions in the air.

So, the two important things that need to be considered are how much time we can get in the air, and how fast we can rotate in that amount of air time. All jumps are completed in a fraction of a second. Elite figure skaters can get about 0.5s air time. Even Michael Jordan has less than 1s of air time - long as he may seem to hang in the air! In fact, a quick computation will show that jumping 1.2m (~4ft) high would only give 0.97s in the air.

Next, how fast can we rotate? A skating doing a quad toe or quad sal would rotate approximately 7rev/s. Let's say one day we will have skaters being able to generate enough rotational force to make 9rev/s. Even so, with 0.5s in the air, that would only give 4.5 revolutions - enough for a quad Axel, but not the quint!

However, we have not even considered that effort put into generating rotational force may also take from the energy put into generating the vertical height...

So, even though I have not done all the theoretical calculations and thorough check of physical limitations, it does seem rather unlikely that we will see a quint Axel... or at least not one that is edited and put on YouTube!

Meanwhile, to share an interesting article I came across, here is a paper on "Biomechanical conditions for stabilizing quadruple figure skating jumps as a process of optimization" by Karin Knoll & Thomas Härtel.

1 comment:

Larry Boltovskoi said...
This comment has been removed by the author.