----- Original Message -----
Sent: Tuesday, April 11, 2006 9:35 AM
Subject: Re: [PSUBS-MAILIST] Water nozzle propulsion
Is your electric motor brushless or sparkless? Take care if you install it in your battery compartment without first isolating it from the batteries. Risk of hydrogen explosion.
Just an idea, but after you form the nozzles from wood, have you considered using that to make a mold and pour the nozzles out of brass? Brass would be more corrosion
resistant than aluminum or mild steel. You could go to a local foundry or even make the mold yourself.. You could also use wax to form the nozzles
and then pour the mold material over the wax, and then when the mold material had hardened and you drill a hole to pour your brass into the mold, the wax will evaporate and
the brass will fill the void where the wax was. Called the lost wax process for molding an object. Unfortunately the mold is only good for one usage because you destroy it when
you break it apart to get to the molded piece. I am interested in these underwater water pumps for sub propulsion, but I know nothing about them. Is it something like the propulsion
used for a jetski but with an electric motor instead of a gas motor? Or is it more like an enlarged bilge pump in operation? Or is it more like a submersible in pipe well pump?
I only know about electric motors and propellers like on my wetsub. The water pump idea intrigues me because I like the idea of someone being able to install the electric part inside their sub
and the rest outside and therefore not need any pressure compensation like you would on an electric motor with a prop. It would be great to see some video of this in action underwater.
----- Original Message -----
Sent: Tuesday, April 11, 2006 7:46 AM
Subject: RE: [PSUBS-MAILIST] Water nozzle propulsion
No, right now I know the predicted rate of flow from the external water pump based on the known performance of my hydraulic gear motor and the water pump itself. It is 4 gallons per second, at full open.
I expect I will have to experiment with the shape of the nozzles to achieve the maximum thrust possible. I plan to make the nozzles shapes out of hard wood and then hand form them out of either aluminum or mild steel sheet metal. There is some data available on nozzle shaping and I hope to utilize it in my fabrication.
As to the question of noise, that is pretty easy to solve using noise absorbing/deadening sheet material like E.A.R. produces. I have a lot of experience installing it in commercial aircraft and it makes a remarkable difference. The DC motor can be isolated from the crew area by a simple bulkhead, and the mechanical "compartment" can be covered by this sound isolating material. I already know how loud the motor is as I have it running with the system on my test bench. It would definately be possible to install the motor in my lower battery compartment with little or no trouble. The hydraulic lines do not care where they have to be run in order to work.