<html><head></head><body><p dir="ltr">The counter rotation is a function of the design of the gearbox. It is possible to do it either way, but having e.g. one right handed prop on the forward shaft and one left handed prop rotating in the other direction on the after shaft counters wasted energy from discharge thrust that is circumferentially accelerated. Of course, there is some wasted energy associated with the gearbox, so it's not all positive, but I think I'll come out ahead in my specific application.</p>
<p dir="ltr">I wasn't going to vector one big thruster through a large range of motion, but rather have thrusters mounted on either side, with some degree of movement in order to selectively optimize the thrust direction depending on commanded ahead/astern, lateral, or rotary movement.</p>
<p dir="ltr">Any such scheme has to carry all of the thrust through to the vessel, so it requires some thought on how to best arrange.</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On March 25, 2016 8:36:11 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div id="yui_3_16_0_ym18_1_1458959276707_2871" dir="ltr"><span id="yui_3_16_0_ym18_1_1458959276707_2870">Autorotate, maybe wrong word, I meant both props turn opposite directions. Are you thinking of vectoring in multiple directions or rotating 360 degrees.</span></div><div id="yui_3_16_0_ym18_1_1458959276707_2871" dir="ltr">I was once working on a single thruster design. The thruster could point in any direction so the sub only needs one thruster. </div><div id="yui_3_16_0_ym18_1_1458959276707_2871" dir="ltr">Hank</div> <div class="qtdSeparateBR"><br /><br /></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida
Grande, sans-serif; font-size: 16px;"> <div dir="ltr"><font size="2" face="Arial"> On Friday, March 25, 2016 5:12 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br /></font></div> <br /><br /> <div class="y_msg_container"><div id="yiv5672095176"><div><div dir="ltr">It will be similar to a surface vessel bow thruster, only instead of a thruster tunnel in a hull, it will be housed in a symmetric nozzle which itself can be vectored with an actuator. I'm designing the gearbox from scratch - a few off-the-shelf spiral miter gears, tapered roller combined load bearings, shafts, seals and ports for oil circulation. Not sure what you mean by autorotate? They will not freewheel, if that's what you mean. Zero output on the hydraulic servovalve will lock off fluid flow (and thus lock out motion), although the gearbox will still be pressure compensated from the discharge side.</div>
<div dir="ltr">Sean</div>
<br clear="none" /><br clear="none" /><div class="yiv5672095176gmail_quote">On March 25, 2016 3:59:31 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv5672095176gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div class="yiv5672095176yqt6911423645" id="yiv5672095176yqt72305"><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px;"><div id="yiv5672095176yui_3_16_0_ym18_1_1458943066308_3543">Hi Sean,</div><div dir="ltr" id="yiv5672095176yui_3_16_0_ym18_1_1458943066308_3543">It sounds like you are going for something like a hydraulic bow thruster, I am not sure if the props autorotate.</div><div dir="ltr" id="yiv5672095176yui_3_16_0_ym18_1_1458943066308_3543">Hank</div></div></div><div style="margin-top:2.5em;margin-bottom:1em;border-bottom:1px solid #000;"></div><pre class="yiv5672095176k9mail"></pre><hr /><br clear="none" />Personal_Submersibles mailing list<br clear="none" />Personal_Submersibles@psubs.org<br clear="none" /><a rel="nofollow" shape="rect" target="_blank"
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