Ed;
There can be turbulent flow in water too-- look at a boat propeller.
A simple "beam breaker" system should suffice for timing-- it works for the
SCTA and NHRA. I wonder if a smooth ramp would simulate the ground effects?
Without a doubt you'd want to use ball- bearing wheels. Maybe you could
guide it down the ramp with a thin nylon monofilament fishing line and a
small eye hook. Of course if it doesn't run straight that would indicate a
problem with the shape.
Regards, Neil Tucson, AZ
-----Original Message-----
From: Ed Weldon [mailto:23.weldon@comcast.net]
Sent: Wednesday, January 16, 2008 11:55 AM
To: neil@dbelltech.com; 'Don McMeekin'; 'Keith Turk'
Cc: 'land-speedsubmit'; 'Elon'; NT788@comcast.net
Subject: Re: [Land-speed] [BULK]Re: Polar Moment
Neil--
Water is mostly laminar flow. Air is turbulent. Big difference.
That said, it wouldn't be all that hard to pack a 1:25 model body with lead
wheel weights and mount the wheels on little free tunning bearings.
I think you'd want to close it up pretty tight so it wouldn't shed air
bubbles. Maybe design the carriage with the wheels so the body can be
turned relative to direction of travel. I'd look at using "G" scale model
train track (but cover the ties) and maybe cut up one of the trucks adding a
section between the axles to lengthen the wheelbase. You have "sparky"
experience. Can you contrive underwater sensors to signal the passing of
the model? Otherwise refraction effects from ripples could upset the visual
ques for stopwatch work.
Ed
----- Original Message -----
From: <neil@dbelltech.com>
To: "'Ed Weldon'" <23.weldon@comcast.net>; "'Don McMeekin'"
<landspeed@columbus.rr.com>; "'Keith Turk'" <kturk@ala.net>
Cc: "'land-speedsubmit'" <land-speed@autox.team.net>; "'Elon'"
<saltfever@comcast.net>; <NT788@comcast.net>
Sent: Wednesday, January 16, 2008 9:51 AM
Subject: RE: [Land-speed] [BULK]Re: Polar Moment
> I've often wondered if I could investigate the aerodynamics of a design
by.....
> 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. ....
> Regards, Neil Tucson, AZ
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