Water tunnels are used a lot. So this idea seems good to me. But there
are some issues to contend with. You need to do a dymnamic similitude
analysis to determine the relationshipos between the water, air, mass,
and time effects. The Reynolds numbers come into play as do roughness
factors etc. Now having said that it is a cool idea. How would you time
the roll down the ramp? A second or two might mean a big difference in
perceived performance.
mayf
neil@dbelltech.com wrote:
>Ed;
>
>I've often wondered if I could investigate the aerodynamics of a design by
>using a scale model in water instead of air. The drag effects, etc should
>show up at quite low speeds in water compared to air since its density is
>far higher. Granted, water isn't compressible like air but we're talking
>about subsonic vehicles so this may be practical-- what do you think?
>
>My idea is to do the drag measurements with a minimum of instrumentation.
>Simply build a smooth ramp and place it in a swimming pool at a known angle
>and let the model roll down the ramp for a measured distance. The faster it
>covers that distance, the lower the drag. The distance would need to be long
>enough for the model to reach its terminal velocity. Make the model fairly
>heavy to eliminate the buoyancy effects.
>
>Jon might have to chip a hole in the ice, though :)
>
>Regards, Neil Tucson, AZ
>
>-----Original Message-----
>From: land-speed-bounces+neil=dbelltech.com@autox.team.net
>[mailto:land-speed-bounces+neil=dbelltech.com@autox.team.net] On Behalf Of
>Ed Weldon
>Sent: Wednesday, January 16, 2008 12:20 AM
>To: Don McMeekin; Keith Turk
>Cc: 'land-speedsubmit'; Elon; NT788@comcast.net
>Subject: Re: [Land-speed] [BULK]Re: Polar Moment
>
>
>....I wonder if some of the scale model body shapes available like to the RC
>model builders are big enough to test in a small wind tunnel. I even wonder
>if this could be a sophisticated "garage project? Anyone have some
>engineering school contacts? This could be a neat senior or graduate level
>project for a mechanical engineering student or a group.
>
>Ed Weldon .....uhhhh........off on the edge again.
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