Eric,
he used a spring scale. The e-drive was a proprietary one with a tilting
ability. There was a certain moment arm to spring scale from the tilting
pivot, and of course a certain arm to prop center as well. A small
hysteresis was noticed, but it was removed from results by measuring a
mean value between hysteresis limits. In my google web page, there are 4
pictures of the boat, tilting system, and prop. Most of the pictures
here are about a second generation boat project, but the 4 pictures at
the end of the list are about the said system (spring scale is not
assembled in these pictures):
https://sites.google.com/site/reinourala/ponkku2010
reino urala
On 08/29/2011 07:43 PM, Eric wrote:
> Hi Reino,
>
> Sounds interesting. How did your friend measure the thrust at the drive to hull assembly?
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, redu<reino.urala@...> wrote:
>> My friend
>> measured el-drive propeller efficiency by measuring the thrust force at
>> drive-to-hull-assembly, while the boat was moving normally on sea. The
>> prop output power is of course P = v * F, where v = boat speed, and F =
>> measured thrust. Motor output power is of course current * voltage *
>> specified motor efficiency. He has a super propeller with wide aperture
>> and narrow blades. The measured super prop efficiency was 60%.
>>
>> reino urala
>>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
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