Underwater speed?

[Ramius]

I think that the max depth is about 50'? There is a pressure sensor to prevent the sub from going too deep. R/C subs operate at 54 MHZ which has little difficulty penetrating water. The video camera system for the periscope operates at 1.2 GHZ. FYI 2.4 GHZ is the frequency for microwave ovens so to use this frequency would result in you only warming the water around your antenna! I work at Fox Television and have a ham radio license so a friend of mine and I designed an antenna that sends the video in an up direction only so the periscope will work underwater which has been tested. Every 33' the water pressure doubles from surface pressure so if you only used one pressure sensor you would be seeing the depth as speed when stationary. I think differential pressure is the way to go, water pressure on the bow as you move minus the pressure at depth. What I do not know how to calculate is velocity. Pictures are similar to mine.

Thanks to all and best wishes, Ed

[languer]

That is quite awesome. Could you have some sort of towed array to serve a GPS antenna? That way a GPS module can give you the speed, position, etc.

Another method I saw was to use two ultrasonic transducers; one on front and and one on back. The time for a pulse to reach the rear transducer through the water will be a fuction of the speed of the boat (think SONAR).

[Ioannis]

Very impressive! Like it a lot!

Ioannis

[Demon]

What about 2 pressure sensors front and back? The difference tells you velocity.

Robert

[Acetronics2]

Nice thing ...

@ 2000 Euros per piece ( 2500 US $ ) ...

Alain

[AvionicsMaster1]

Wow! Seems like such a simple question but I think it might require a complicated answer.

This site http://www.engineeringtoolbox.com/dy...re-d_1037.html can get you close but you've got to know density. This wiki site http://en.wikipedia.org/wiki/Density has a chart that shows water density at temperature.

So if you subsitute the fluid density p(rho) with the equation m/V your equation would be pd = 1/2 (m/V) v2. Solving for velocity would be, well I can't figure out how to write that here but you get the idea. What all this is trying to say is you'll have to get temperature somewhere.

I agree with all in that I'd like to see how you solve this problem.

[Demon]

(Talking out my wazoo on this)

But would density have a huge impact?

Is the sub going to be used in extreme temps, or only between ~15C - 20C?

Personally, I'd use it in temps and depths that I could dive to get it back (got no diving suit). But if you want to set a record crossing the English Channel, that's different.

Robert