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Ned C. Forrester

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Roger H. Maloof, Ned C. Forrester and Charles E. Albrecht, A Brushless Electric Propulsion System for the Research Submersible Alvin, IEEE Oceans '86 (presented but not published), Sept. 23-25, 1986

Alvin has been fitted with a new propulsion system using multiple thrusters directly driven by brushless electric motors. The high efficiency of direct drive out weighs the use of small thrusters on a large vehicle. Analysis and test data support the improved reliability and performance compared to Alvin's old hydraulic propulsion system.

[NB: In the paper we assumed Alvin to be a piece of plywood with thrusters. The analysis we used from PNA (ref 1) is that for a jet boat, which draws its inlet water through a duct in the hull at right angles to the direction of thrust, and thus must first accelerate the water to vessel speed (by pushing with the walls of the duct). In other words, we are assuming that the action of the thruster is to accelerate wake water, BUT that it thus forces more wake water to be generated as a result.

Cal Gongwer (Innerspace Corp. maker of the thrusters) disagrees, and claims that the availability of wake water is an advantage, and that the system should be analyzed as a "wake adapted propeller". See:

I still think our original analysis is correct, but I do not have data to prove that. (NCF 2007)]

FILE » Alvin_Elec_Prop.pdf
PDF of scan of paper, 20 pages.

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