[SML] Extremely low profile air caster?

[Rick Clever]

This sounds almost like a hovercraft. Maybe look in to their
construction and see if it can be adapted.
On Thu, Oct 4, 2018 at 9:03 AM Joe Dunfee via Stagecraft
<stagecraft at theatrical.net> wrote:
>
> I was in a rehearsal, when at the end of a dream sequence, the director
> asked the character to "float" away as the dream faded.  He said
> ideally, she would just move backwards, without walking. But he just
> asked her to walk backwards smoothly.
>
> That got me wondering if it was possible to do.  In this case, the
> actress is actually starting out kneeling, so she can simply stay
> kneeling, so she is well braced if a platform pulls her.  However, to
> not look like she is on a platform, the platform would need to be very
> low profile.
>
> I 1st though of just dragging a piece of 1/4" ply, or linoleum, perhaps
> with Teflon on the underside if really necessary.
>
> Then, I thought of air casters.  The commercial heavy-duty ones are
> designed with what looks like a bicycle inner tube.  But, they also tend
> to lift the platform a few inches as the "inner tube" inflates. Then, I
> thought of the standard air-puck that is used to demonstrate Bernoulli's
> principal, when the moving air creates a lower pressure, so the puck
> actually adheres to the table surface. The flowing air also reduces
> friction to near zero.  So, the air puck is both levitated, and also
> held down.
>
> Those air pucks have nothing more than just a flat surface on the
> underside. So, they are very low profile.  But, a quick test using a
> large wood circle was unsuccessful. Though, the air pressure for the
> number of square inches should have lifted the disk. But so there are
> other issues. I imagine the air pressure needs to overcome the weight of
> the disk by the surface area of the air inlet.  But, even lifting the
> disk a bit to help the process didn't get it to float.
>
> My air source was a very old CPAP machine (that helps people breath at
> night).  It provides up to 0.26 PSI at a pretty high flow rate, and most
> importantly, is very quiet. Newer ones all have security built in, so
> that it takes a password to set the pressure.  So, I am looking for a
> reasonably affordable source for just the fans, so I won't have to
> scavenge for them.  Note that these are brushless, so they would need a
> motor controller.
>
> Any air-puck experts out there?  I am sure a lot of people in theater
> would love to see an extremely low profile air-caster.
>
> -Joe
>
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-- 
Rick Clever
Technical Director
Owens Community College
567-661-7930