Are you designing the sub. to meet performance specifications?
Does weight matter or does it interfere with the indented performance.
Some time, you may have to cut the weight down from the start.
If this is the case the weight and size of the shaft will matter and you may
have to select the proper material to maintain the weight requirement.

wrote in message
ups.com...
Michael wrote:

I'm making a large scale (13ft) model submarine and am currently
designing
the propulsion unit for it.

Try going to psubs.org. They're building manned ones, but as small as
your model. Someone there can lead you to the answer.

M

wrote in message
...



Are you designing the sub. to meet performance specifications?
Does weight matter or does it interfere with the indented performance.
Some time, you may have to cut the weight down from the start.
If this is the case the weight and size of the shaft will matter and you
may have to select the proper material to maintain the weight requirement.

wrote in message
ups.com...
Michael wrote:

I'm making a large scale (13ft) model submarine and am currently
designing
the propulsion unit for it.

Try going to psubs.org. They're building manned ones, but as small as
your model. Someone there can lead you to the answer.

M




Thanks Guys,

M,

I'm a member of the Psubs mailing list but I must admit I didn't think to
ask them.

Marierdj,

I've worked out the sub has to weigh around the 2000kg mark before it will
sink, and generally speaking you have to add lots of ballast to get 'em to
dive so not too worried about weight.

Steve,

I've done the math, and using the data on the motor, I've calculated that
the max torque is 0.78Nm (7 pound inch) and with a shaft length of 1m max.

Cheers,

Michael