Thanks for the responses Dave, it is great to engage in this kind of dialogue.
Quote:
Originally Posted by davei
...Fortunately, my son is a little smarter than I am and can hold more variables in his head than I can. He is largely responsible for the evolution of the technique...Early on in the evolution of Champion plastic we had unwanted bubbles and fought to get rid of them. Now, we are embracing and controlling the pattern...I think it's very cool and am very proud of my son, who is the architect of the technique.
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Great story...and nice to see that Innova will be in good hands well into the future!
Quote:
Originally Posted by davei
...does not have bubbles in the flight plate, just the rim...I've heard lots of speculation about what the bubbles do dynamically to the flight...
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This is pretty standard physics, in terms of how the disc's mass distribution will affect turn/fade. The moment of inertia of a uniformly flat disc (e.g., hockey puck) is:
m*r^2/4,
where (m=mass, r=radius). The moment of inertia of a ring (e.g., Aerobie ring) is:
m*r^2/2,
i.e., twice that of a uniform flat disc. The moment of inertia of an Innova disc is the sum of the flight plate (flat disc-like) and rim (ring-like):
m_fp*r_fp^2/4+m_rim*r_rim^2/2,
where _fp=flight plate and _rim=rim (more precisely, r_rim is the mass-weighted radius of the rim). If the mold is the same, then r_fp and r_rim do not change with addition of bubbles, but m_fp and m_rim do change. Changing the mass of the flight plate (by altering the bubble density) therefore has half the sensitivity upon the total moment of inertia of the disc than does changing the bubble density in the rim.
Translation back to ordinary English: For a disc with the exact same shape, adding bubbles to the rim will make the disc turn/fade more than adding bubbles also to the flight plate. I predict that this is only a weak effect, and that subtle changes in shape will probably be the more important factor owing to the strong non-linearity of aerodynamic flows and forces.