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Author Topic: Counter-rotating propellers for stunt - Himax CR3516-XXXX  (Read 1256 times)

Offline Matt Piatkowski

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Counter-rotating propellers for stunt - Himax CR3516-XXXX
« on: July 23, 2019, 12:12:07 AM »
Hello,
I have received Himax CR3516-1030 counter-rotating propellers system for testing.

http://Http://Http://www.maxxprod.com/mpi/mpi-266.html shows this system with 12x6 and 11x8 APC propellers for use with the 3S battery. It is stated in CR3516.pdf (attached) that "Efficient Operating Current =30-36 A per rotor, 40A Max 15 seconds per rotor".

I have found that both motors have 16AWG insulated braided copper leads.

Let's start from this finding. Will 16AWG braided copper leads survive 30 Amps. per motor supplied by the ESC as alternating current? The web available data in this regard is, of course, inconclusive.

Thank you and Happy Electric Flying.
M

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Offline TDM

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Re: Counter-rotating propellers for stunt - Himax CR3516-XXXX
« Reply #1 on: July 23, 2019, 06:35:56 AM »
Matt I am guessing that if the manufacturer put those wires in and specifies the max continuous and 15sec max amp rating it should be fine and I would not second guess it.
APC props might be on the heavy side and I am partial to the XOAR props.
How heavy is this setup?
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Offline Matt Piatkowski

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Re: Counter-rotating propellers for stunt - Himax CR3516-XXXX
« Reply #2 on: July 23, 2019, 08:31:51 AM »
Hi TDM,
Like you probably know, many Chinese companies "massage" the technical data to make different things look better.
I am not saying they all do it but it is possible.

The assembly (motors, front prop. adapter, 2 props and 4xM3 screws mounting the rear prop) as shown in the attachment weights 312 grams (11 oz.). The propellers are 12x6 carbon composite hollow core and each weights only 15 grams (0.53 oz.). I saw these props in the F2B action and they were exceptionally efficient and stiff - the RTF 1960 grams (69 oz. ), 670 in^2 wings plane flew the entire pattern very well. This plane crashed before and the repairs added at least 2 oz. and the flier used two Spin66 ESC, weighting in total 146 grams plus a very crude and heavy parallel harness.

If one uses two 35 Amps ESC, the "smart and light" harness to split the current and the 3S 4000 mAh battery with the mounting Velcro straps, the entire power plant should be around 800 grams. It is quite realistic to build the full size (59" wings span) stunter weighting 1,000 grams if you know how to optimize the weight. Consequently, the entire RTF plane with the counter-rotating props can weight the same as the single prop plane.

Regards,
M
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Offline Archie Adamisin

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Re: Counter-rotating propellers for stunt - Himax CR3516-XXXX
« Reply #3 on: August 03, 2019, 06:50:30 AM »
Matt,

I'm looking forward to seeing how your flight testing goes. 

In reality, not sure what this will do performance wise.  From a setup standpoint it adds complication and all of us know what that can lead to in the heat of battle. Pitch to diameter ratios and prop to prop spacing will be critical.

I still think the single motor gearbox setup is still a better option.  It does limit the information about prop loading, but that can be fine tuned with a 2 motor setup.  Prop weight and stiffness will be important as well so that the dynamics don't rip the front end off. 

Bottom line for me, it makes an avenue for some great semi scale projects.

Archie Adamisin
Burlington, KY
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Archie Adamisin
Burlington, KY

Offline Matt Piatkowski

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Re: Counter-rotating propellers for stunt - Himax CR3516-XXXX
« Reply #4 on: August 21, 2019, 12:05:46 PM »
Hello,
Please see the attached. The tests will continue.
Thanks,
M
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Offline Tim Wescott

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Re: Counter-rotating propellers for stunt - Himax CR3516-XXXX
« Reply #5 on: August 21, 2019, 03:41:45 PM »
Quote from: Matt Piatkowski on July 23, 2019, 12:12:07 AM
I have found that both motors have 16AWG insulated braided copper leads.

Let's start from this finding. Will 16AWG braided copper leads survive 30 Amps. per motor supplied by the ESC as alternating current?

What do you mean by "insulated braided"?

Sizing wire and cable gets to be a black art -- there's the size that you can put in your house, that's designed so that stupid homeowners can abuse it and not catch their houses on fire; there's the sizes recommended for cars, with similar constraints; there's the size that you can have running through open space with lots of airflow; there's the size that you can bury in a thermally insulated cable.  Finally, there's the size that works in a motor, where the armature will go a long way toward conveying heat away from the wire, and where a bigger wire makes the motor heavier.

I'm not sure about a single strand of 16 gauge wire -- but it may work.  However you say "braided" -- in that case, the number of conductors in the braid makes all the difference in the world.  Very roughly, the current carrying capacity is proportional to the total copper area, not the area of each strand.
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AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Matt Piatkowski

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Re: Counter-rotating propellers for stunt - Himax CR3516-XXXX
« Reply #6 on: August 21, 2019, 09:29:19 PM »
Hi Tim,
16 AWG works well. I have tested the system to 34 Amps.
M
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