[PSUBS-MAILIST] Brushless thruster test 2

Sat Feb 6 22:06:33 EST 2016

For the MKP-33, with no nozzle, the 67 lbs bollard thrust was with the
motor being supplied 1530 watts or a little over 2 hp and current was about
42 amps.

I think you are right on the reason for the drop off.

 I must have missed the email on the bollard testing, I will go back
through my emails and see if I can find it.

Cliff

On Sat, Feb 6, 2016 at 6:50 PM, Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi Cliff,
> thanks for the data, am interested in any more you get.
> I wrote an email on testing with a link to a bollard test set up for a
> DPV.
> If you didn't get it I will re-send. I have missed some emails lately.
> The Vetus prop is a square ended prop designed for nozzles. I didn't try
> it with a nozzle. They have a range of props.
> Vetus, 6 Blade Bow Thruster Replacement Propeller
> <http://www.go2marine.com/product/19103F/vetus-6-blade-bow-thruster-replacement-propeller.html?WT.srch=1&WT.mc_id=gb1&utm_source=googlebase&utm_medium=productfeed&utm_campaign=googleshopping&gclid=CKWmtc2v5MoCFVgnvQodL7cJMQ>
>
>
> [image: image]
> <http://www.go2marine.com/product/19103F/vetus-6-blade-bow-thruster-replacement-propeller.html?WT.srch=1&WT.mc_id=gb1&utm_source=googlebase&utm_medium=productfeed&utm_campaign=googleshopping&gclid=CKWmtc2v5MoCFVgnvQodL7cJMQ>
>
>
>
>
>
> Vetus, 6 Blade Bow Thruster Replacement Propeller
> <http://www.go2marine.com/product/19103F/vetus-6-blade-bow-thruster-replacement-propeller.html?WT.srch=1&WT.mc_id=gb1&utm_source=googlebase&utm_medium=productfeed&utm_campaign=googleshopping&gclid=CKWmtc2v5MoCFVgnvQodL7cJMQ>
> Due to your browser's configuration you can not order online. Please order
> by phone or contact us. Vetus, 6 Blade Bow Thruster Replacement Propeller
> Mfr.
> View on www.go2marine.com
> <http://www.go2marine.com/product/19103F/vetus-6-blade-bow-thruster-replacement-propeller.html?WT.srch=1&WT.mc_id=gb1&utm_source=googlebase&utm_medium=productfeed&utm_campaign=googleshopping&gclid=CKWmtc2v5MoCFVgnvQodL7cJMQ>
> Preview by Yahoo
>
>
> I am not sure whether you can get a left & right handed propeller.
> I didn't run the tests long. I had a smooth start option programmed in to
> my controller
> so it was a bit slow getting to full throttle. As per the instructions in
> the email link I sited,
> it is best to get it up to full speed fast before you create a strong
> flowing current.
> This is most probably why your amps went down, as the water was initially
> stationary
> & then started flowing & lowering the load. Typically a displacement boat
> can have 50% propeller slip or more so
> you could have been doing a bit of a wheel spin initially & getting the
> revs up, then they might have come down
> as the current flowed.
> I am not sure why I got the large 3,800 W & only 81 lb thrust unless
> something is shorting to the aluminium housing
> under load. It could be boundary effect???
> I have measured the max rpm out of water but can't measure it in water at
> the moment. That will
> be my stage two testing.
> The thrust results were repeatable on the yamaha prop up to 10 kg (22 lb)
> & then they seemed to go a bit haywire,
> so this indicates boundary effects.
> The 6 blade Vetus prop was more consistant above this, but maximum thrust
> was 24 kg at 2,500 W.
> How many Watts were you drawing from the battery to get the 67 lb thrust?
> I will need to re-think this & order stuff in from overseas & maybe make
> another housing before I test again.
> Cheers Alan
>
> ------------------------------
> *From:* Cliff Redus via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Sunday, February 7, 2016 11:29 AM
> *Subject:* Re: [PSUBS-MAILIST] Brushless thruster test 2
>
> Thanks Alan.  To reciprocate, attached are our initial test last week.
> The variable pitch prop is not out of the machine shop yet so main goal was
> to evaluate test rig with Minn Kota MKP-33 prop ( two blade, 4" pitch, 11"
> diameter)  that matches with the MK-101 lower unit. We are going to use the
> MK-101 and MKP-33 prop as the control for our new prop.  We also tested a
> Kipawa 80/01 (3 bladed prop, 5"pitch, 11" diameter).  The Kipawa prop will
> fit in my ducted nozzle so measured the bollard thrust with and without the
> nozzle.  We are still analyzing the data but some initial results.  Bollard
> thrust of the MKP-33 of 67 lbs is low relative to the 101 lb rated thrust.
> A quick look on web shows that manufacture thrust rating are 30-40% higher
> than a bollard thrust test.  Test rig is fully calibrated.  With the Kipawa
> prop, the bollard thrust is about 10% higher when using the nozzle than
> without.  BTW, this is an open water prop and is not designed to be used
> with this nozzle. A ducted nozzle prop needs to have more of a square tip
> to keep water from moving from the high pressure side of the blade to the
> low pressure side.   Like you my initial reaction is that we could be
> having the same boundary or end effect because of the proximity to the pool
> wall.  We did prove the system worked. Not sure why both rpm and current
> are dropping over time when the measured battery voltage is constant?
>  Next week, we are going to repeat the test with the thruster oriented
> along the long axis of the pool and see how the thrust compare.
>
> On your test, a couple of questions:
> 1) How long did run each test point?
> 2) On the first test sequence, 3800W and 81 lbs bollard thrust for input
> HP of over 5.  This seems like quite a bit of power to develop this amount
> of thrust. Do attribute most of this to this boundary effect or
> recirculation affect?
> 3) On each of these test points, your are stepping through higher and
> higher power to the thruster.  For any one of these points, how repeatable
> is thrust?
> 4) Thrust is proportional to density * n^2*Dia^4.  I think to be able to
> make sense of data from different props with different diameters and
> pitches, you need an angular velocity or speed measurement.  Can you
> measure the motor speed with this type of motor.  For our test we use a
> proximity switch and count pulses to measure speed.
> 5) Are you planning on testing any ducted props?
>
> Cliff
>
>
> On Sat, Feb 6, 2016 at 2:41 PM, Alan James via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
>
> ------------------------------
> *From:* Alan James <alanlindsayjames at yahoo.com>
> *To:* Personal Submersibles General Discussion <seaquestor at gmail.com>
> *Sent:* Saturday, February 6, 2016 11:18 PM
> *Subject:* Brushless thruster test 2
>
> This is mainly for Cliff's benefit, as he is going to be doing some
> thrust testing.
> Tested 2 different props out. One being the same as the first test, the
> yamaha 7&1/4" x 4" pitch
> & the second was a Vetus 6 blade 108 mm ( 4")  for 25kg bow thruster. No
> stats on the pitch but it
> looks about 180mm or 7".
> My watts measurement is done off the battery whereas other people quote
> their output at the motor.
> I am comparing my motors performance to statistics from commercial
> thruster brands but not sure
> where they are measuring there power from.
> Had some wacky results from the yamaha prop again. It was the more
> powerful & I think I am getting what
> is called a "short circuit" effect through having the motor about 28" out
> from the pool edge & in about 3ft
> of water. Short circuit is where an edi is formed & the water moves from
> the output to the input in a semi
> circle around the thruster. This is caused by water bouncing off a pool
> wall, or in my case the inlet flow
> bouncing off the wall or pool bottom.
> I was running off a 40V 5 amp  Lipo battery & the voltage dropped a bit
> during the tests.
> Ist test was 10 kg (22 lb ) at 500 W
> 2nd 11 kg at 1000 W & 39 V
> 3rd 15 kg at a huge 3,400 W
> 4th 37 kg at 3,800 W & 85 amps.
> As you can see some inconsistent results there, and some missing figures
> like amp draw, as I needed
> an assistant to read the figures.
> Next is the Vetus prop.
> 1st 10kg  547 W  39 V
> 2nd 11 kg  634 W  11 amps  37.81 V
> 3rd  15 kg  998 W  27 amps
> 4th  20 kg  1700 W  39 V
> 5th  24 kg  2500 W
> It's amazing what a difference a prop makes.
> In conclusion, I need to ditch this rig & buy a longer plank of wood to do
> tests in the middle of the deep end.
> I have a more sophisticated volt / amp meter that stores results & plots
> on a computer & I need to employ that.
> I need to buy a similar motor but a sensored version, as there was too
> much cogging at low speed.
> Sensoreless motors read the back emf produced by the motor to ascertain
> the position of the rotors & can stop /start
> & rotate backwards on low speed where there isn't enough back emf produced.
> I need to replace my motor controller with a sensored controller, probably
> Kelly & buy a bigger life po4 battery.
>    I also want to wire the motor to a WYE configuration which will give me
> .73 less rpm. So will gear it down a bit.
> Some good news is I have found people on boating forums adapting these RC
> brushless motors & an absolute
> guru who uses these motors for traction vehicles & has posted pages of
> information on them.
> Cheers Alan
>
>
>
>
>
>
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