Noise would be one of several issues--but an important one. I've listened to way too many of them to doubt that. The Mermaids were electro-hydraulic, for instance and even with the plant in a foot well (welded through the hull, by the way) they were insufferably loud. It's mighty tiresome after awhile. And in the ROV business, one of the major obstacles in the early years was to filter all the junk that rattled into the electronics.
I'll stick with a hydraulic unit for manips, but not for propulsion. I might lean toward the jet pump with a direct drive thruster motor running it, as an alternative.
Hi Jon,
I believe Gary Boucher as a hydrualically driven motor in his sub.
I remember complaining about how loud it was and how if he was to
do it again, he would avoid hydraulic motors at all costs (or
something like that).
Ian.
On Mon, 10 Apr 2006 21:06:41 -0400
"Jon Wallace" <jonw@whoweb.com> wrote:
> Cool...you took it a step further than I had considered. I hadn't even
> thought of a hydraulically driven pump which would completely isolate the
> electrical motor. So have you calculated how much "thrust" you will be able
> to produce at the nozzles?
>
> Jon
>
> -----Original Message-----
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org]On Behalf Of John Gaertner
> Sent: Monday, April 10, 2006 8:10 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Water nozzle propulsion
>
>
> That may very well be, there is going to be some efficiency loss between
> the pumps and one motor. But I am able to use a single, powerful 24V DC
> motor running at an efficient, constant speed, turning a single gear driven
> hydraulic pump, inside my pressure hull. No requirement for pressure
> compensation. The hydraulic drive is completely speed controllable with a
> single flow control valve. The hydraulic reservoir can be used as a heat
> sink or exchanger depending on the internal temperature of the submersible
> and the surrounding water.
>
>
>
> The only hull pass throughs I will have for this system are for the out
> going pressure line ( 0.5" ) and the return line ( 0.75" ), both made from
> stainless steel pipe. The hydraulically driven water pump will be mounted
> outside my pressure hull. The nozzles will be directed with the excess
> hydraulic pressure I generate, and will also be hooked up to these modest
> pass throughs. The nozzless will be able to be rotate independently through
> 360 degrees and the submersible should be able to turn on a dime.
>
> No chance of fouling a prop on anything or ingesting anything.
>
>
>
> I feel it is worth the effort on my part to try some thing a bit
> different but that I feel has been proven, at least by one submariner, to be
> successful.
>
>
>
> JG
>
>
> -----Original Message-----
> From: Brian Cox
> Sent: Apr 10, 2006 5:29 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Water nozzle propulsion
>
>
> I would say just generally, that every time you have to go from one type
> of power transmission to another you will have a certain amount of power
> loss due to the coefficient of friction for that particular device. The
> most direct and efficient transmission of power would be a electric motor
> going directly to a prop turning in the water. If you are going to, first a
> electric motor to a hydraulic pump and then second, from a hydraulic pump to
> a hydraulic driven water pump you will be adding many steps which will
> absorb energy every step of the way which will manifest it self in terms of
> heat to each device.
>
> Brian
>
>
>
>
> ----- Original Message -----
> From: John Gaertner
> To: personal_submersibles@psubs.org
> Sent: Sunday, April 09, 2006 11:20
> Subject: [PSUBS-MAILIST] Water nozzle propulsion
>
>
> I am working on the design and construction of a hydraulically driven,
> variable speed, water nozzle thruster system at this time. So far I have
> been able to get together most of the necessary pieces: 24V DC motor,
> hydraulic gear pump and hydraulically driven water pump. I still have to
> acquire the necessary supply and return hoses but I am hoping to have some
> basic static testing done by the end of this summer. My intention is to
> power my submersible in a similar manner to the Cousteau subs. I do not see
> this as an inefficient system based on my calculations as many on this list
> do. I will be glad to share my findings once I have some real data in hand.
>
>
>
> Regards,
>
>
>
> John Gaertner
>
> Keswick, VA
>
>
>
>
>
>
> -----Original Message-----
> From: vbra676539@aol.com
> Sent: Apr 9, 2006 12:59 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] motor thought
>
>
> I agree in principal, but spent a few uncomfortable hours in pretty deep
> water struggling with entanglements. The Cousteau jet pump was primitive,
> but effective. By accepting the obvious limitations in power, they were able
> to work three different submersibles through many hundreds of dives without
> entanglement. There is something to be said about that kind of safety
> record, and I think it is worthy of consideration as an alternative method
> of propulsion for psubs. Mind you, I haven't done it, either. My K-350 is
> going back together this summer pretty much as designed (except for lessons
> learned by Dan and a few others, which I will incorporate in one way or
> another). However, I ain't giving up on some kind of pump for future
> reference.
> Vance
>
>
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