[PSUBS-MAILIST] Thruster Test

[Alan via Personal_Submersibles]

Hank,
I was only running it for a short time testing the thrust.
I previously did a temperature test running it at 30 Amps for an hour 
without a prop in water temperature up to 27C, & it kept below 80C.
I am happy with the yamaha 2hp prop & will do an endurance test with
that for 100 or so hours & monitor the temperature again.
Cheers Alan

> On 8/12/2018, at 1:29 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
> How is the heat managing?
> Hank
> 
> On Friday, December 7, 2018, 3:12:00 AM MST, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hi all,
> tested another 2 props today. Both 2 hp yamaha 3 bladed. One was a
> plastic 7&1/4 x 4, the other aluminium & similar but with rounded ends 
> to the blades.
> They both worked much better than the Vetus prop I tried yesterday,
> the plastic prop being the better.
> By comparison the plastic yamaha prop had 60.62 lb. thrust from 1624 W 
> while the Vetus had 45 lb. from 1694 W. Quite a difference; 26.79 Watts per
> pound of thrust as apposed to 37.66 for the Vetus. 
> David, again it showed to be a lot more economical on power to run the
> motor slowly. At 11 lb of thrust it used 12.9 Watts per pound of thrust and
> rose up to 26.79 Watts per pound of thrust at full power.
> So if the batteries are low, go slow. 
> Cheers Alan
> <image1.JPG>
> 
>> On 6/12/2018, at 7:34 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
> 
> Hi David,
> the extension ladder worked but was a bit of an effort pushing it out
> with weight on it. I will grease it before the next prop test.
> As for thrust to watt ratio; I measured this at intervals from 18V to 44V.
> 18.2V, 13.2W per lb. of thrust.
> 26.8V, 19.5W per lb.
> 33.6V, 24.4W per lb.
> 38.4V, 29.9W per lb.
> 44.6V, 37.6W per lb.
> So definitely a loss of economy as you open the throttle. The Vetus prop
> is designed to work in a tunnel & I didn't have one on it. It will be interesting 
> to see how the other props fare in this respect, & if these figures differ much
> when I put a kort nozzle / prop guard on them.
> Alan
> 
> 
>> On 6/12/2018, at 3:58 AM, David Colombo via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Hi Alan, l never thought of using a ladder as a test rig. Was the thrust to watt ratio the same base at different speeds?
>> David
>> 
>> On Wed, Dec 5, 2018, 2:03 AM Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Just did the first test on my latest brushless thruster version.
>> I started with a Vetus bow thruster which is normally housed in a tunnel, but
>> to simplify things I am testing several different propellors without nozzles first.
>> I have a 10mm prop shaft & the various off the shelf props need either drilling
>> out or sleeves made to fit them.
>>    I was getting 38.5 lb. thrust from 1,152 Watts & 45 lb. off 1,694 Watts, which
>> is comparable with some commercial thrusters but not with others. Some 
>> manufacturers are quoting thrust per Watt figures I find hard to believe.
>> Will see how the other props work.
>>    Testing came to an end when the automatic pool cleaner (which I had just
>> moved to the end of the pool) came down & knocked my prop off while I was 
>> jotting down notes. First swim of the summer finding the shaft pin. The prop
>> was held in place more or less by the force of the prop thrust & a tight fit.
>> Picture below is from left to right; load cell mounted on the vertical stationary
>> side of black test jig, motor controller, 48V rectifier with oil compensator on
>> top, grey load cel display, servo tester to control speed & laptop with Vesc Tool
>> program displaying data. 
>> The oil compensator is just for the testing, a much smaller & different system
>> will be on the sub.
>> Alan
>> 
>> 
>> 
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