<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt"><div><span></span></div><div></div><div>Yes 1.6 teaspoons. Just looking at the 101instalations I have seen, I agree, vinyl length seems adequate for reservoir.</div><div><br></div><div>Cliff<br></div><div><br></div><div><br></div> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div dir="ltr"> <div class="hr" style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); border-image: none; height: 0px; line-height: 0; font-size: 0px;" contenteditable="false" readonly="true"></div> <font face="Arial" size="2"> <b><span style="font-weight: bold;">From:</span></b> Jon Wallace via
Personal_Submersibles <personal_submersibles@psubs.org><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, July 22, 2014 9:35 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] Minn Kota 101 - thread spec<br> </font> </div> <div class="y_msg_container"><br><div id="yiv1499595386"><div>
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Cliff, if you cut the temp rise by two doesn't the volume
displacement become 1.6 teaspoons? Regardless, I accept the need
for a reservoir but it would seem the vinyl tube design would meet
that role in the case of small MK motors and can be achieved via
extra length or diameter. My memory of Alec's and Jim's
configuration is that both have more than 3 teaspoons worth of
extra volume in their tubes and perhaps this is why they haven't
seen issues during dives.<br clear="none">
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Jon<br clear="none">
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On 7/21/2014 9:47 PM, Cliff Redus via Personal_Submersibles wrote:<br clear="none">
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<div>Concur Jon that water will act as thermal sink and that the
duty cycle on the thrusters are not severe but I don't agree
that the thermal expansion in negligible. If you assume that
the temperature change I estimated was high by a factor of
two, then you would still end up with 3 teaspoons of oil that
would be forced into the ambient tube. Small but not
negligible. There will be a change in the internal
temperature of the motor from the off position to on and given
the amount of oil in the 101 body, there will be oil that has
to escape. </div>
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<div>Granted, the primary purpose of the compensation is to keep
from exposing the housing to a high differential pressure but
thermal expansion still has to be accounted for in sizing the
ambient reservoir.</div>
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<div>These MK 101 are powerful at almost 1.8 HP at 47 amps when
air filled but there has to be some degradation in power when
filled with oil due to the viscosity difference with air. At
75F, light oil is over 1800 times as viscous as air. IS there
enough power to push a psub about, sure. I am just trying to
come up with what kind of HP loss you get with oil
compensation. </div>
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<div>Does anyone know what rpm these motors max out at in the
water?</div>
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<div>Good point Vance on trying to make the armature as
hydraulically smooth as possible to maximize power when oil
compensated. I wonder how hard this would be to do?</div>
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<div>Cliff</div>
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