Re: [Harp-L] What to do with all those old harmonicas

[Vern <jevern@xxxxxxx>]

Fun with Harmonicar physics:

It requires a pressure of about 1 inch of water to make a harmonica reed speak softly and full volume requires about 5 inches.

One atmosphere = 407 inches of water at 65 degF

At 1" of H2O, the pressure ratio is 407/408  = .9975,  The corresponding velocity is about 67 ft/sec = 46 MPH
At 5" of H2O, the pressure ratio is 407/412 = .9879,  The velocity is about 145 ft/sec = 99 MPH

It appears that the harmonicar must be zipping along at about 40MPH for the harmonicas to sound at all and must be speeding along at 99 MPH to sound at full volume.

In a column of close-spaced harmonicas, only the one in front will feel the full air blast of the car motion.  This means that most of the harmonicas aren't making much noise.  A harmonicar with far fewer harmonicas would not look as impressive but would make substantially as much music.

The video doesn't say anything about how fast the harmonicar must be going to make any music.

If it passes at 50 or 60 MPH, a stationary listener will hear a two note tune.  The doppler effect will raise the pitch as the car approaches and lower the pitch as it departs.

AT highway speeds, the Harmonicar probably gets reduced gas mileage.

All you engineer/musicians out there, please check my numbers.

Vern



On Jan 1, 2012, at 12:04 PM, David Naiditch wrote:

> Make a Harmonicar:
> 
>     http://www.youtube.com/watch?feature=player_embedded&v=IlqsaoY65mI
> 
>     http://www.artcar.blogspot.com/2011/03/mini-carmonica-or-harmonicar-covered-in.html
> 
> At least they are all in the same key.
> 
> --David