Underwater speed?

[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

[tasmod]

Hmm, your driving it with a propeller. Why not a small free rotating prop on conning tower and measure rotations.

There's example code on here somewhere for wind speed anenometer, which is basically same.

Rob

[Demon]

Won't work when surfaced.

Robert

[tasmod]

Conning tower location was just a suggestion, it could just as easily be on hull etc.

KISS. Small prop with photo reflector for pulse count. Mounted in small tube.

Easier to get going, then maybe try sophisticated solutions.

Rob

[NickMu]

Hi Ramius,

Can you provide some more information on your radio controller?
I’m interested on range, maximum depth and more importantly where do you purchase it from?
Regards,


Nick

[Ramius]

Hi Nick!
Here is a link to the radio controller: http://www.conrad-uk.com/ce/en/produ...ains&insert=8X It has two throttles, one for the port motor and one for the starboard motor and a ton of expansion modules! I originally bought it from Ships n' Things. Range and depth are a funtion of the both transmit and receiver antenna's and how they are configured. You basically are trying to simulate a "dipole" for receive and you can use a yagi for transmit. Part of the other factors are where you place all your electrical cables and how you have prevented EMI (Electrical-Mechanical) and RFI (radio frequency) interference. For example motors produce small sparks which are basically a radio signal. So you have to use bypass capacitors. How you ground the motor cases and how you run power all make a difference. The technique I use is called "single point" power and ground where all the power wires connect to one single point and well as the ground wires. In addition power and ground wires have been put in an electric drill and twisted together. There are a lot of technical reasons for doing this. If I strike out with a pressure sensor then the propeller idea will be next!

Best to All, Ed

[NickMu]

Hi Ed,

Thank you for your detailed reply.
I had an application that needed to read the thrust of a jet of water and before our order of force sensors came in we used a paddle wheel to determine the speed of the jet.
The results were within 5% of the real sensors readings.
Depending on your precision and accuracy requirements any of the suggested methods should work but with some penalties.
IMHO your biggest problem will be the changes in water density due to various reasons (salt, temperature…..)

Thank you again and good luck.

Regards,

Nick