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Apr 03, 2018, 04:55 PM
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The gear and gear doors aren't accurate to the full size L-39.
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Apr 03, 2018, 08:43 PM
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Starting to divide it up for the printer.
Apr 04, 2018, 04:31 PM
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The Turnigy outrunner seems to be a LOT less efficient than the Neumotor ORK. 170 g less thrust at 250 W, 260 g less thrust at 500 W, 320 g less thrust at 750 W and 350 g less thrust at 1000 W. It get's pretty hot too. Same fan design. The only difference is a 6 mm hole instead of a 5 mm hole.

It's not running completely smooth. IT occasionally jerks faintly, which I can feel by holding the fan at low throttle. I'm going to reheat the solderings on the motor connectors. They were pre-soldered on both motor and ESC.

EDIT:
It's nothing, just switching at super low rpm. Super smooth at normal RPM. I'm printing an 11 blade fan for it now. The 13 blade fan is way too much for it on 8S. I'm also printing thicker blades for it. I hit 4 kW for a second with the 13 blade fan, at full blast and "Error" on the 5 kg scale. The motor got so hot that the fan housing softened and deformed.
Last edited by Lynxman; Apr 04, 2018 at 05:32 PM.
Apr 05, 2018, 09:59 AM
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I retested the ORK and got the same readings as I did earlier. Way more efficient than the Turnigy Outrunner. The outrunner gets so hot that I suspect something is wrong with it. I'd love to get a bigger ORK, but they're $320 plus shipping and tax. Might as well buy a Stumax 120 mm for $450 instead.

Anyway. The 11 blade fan was a little more efficient with the Turnigy outrunner than the 13 blade fan. I got 3 kW on full throttle. When I tried to run it at 1500 W continously it overheated and melted the duct. The cooling impeller design on the outrunner is awful. The vanes aren't in line with the opening on the holes.

So far my conclusion is that the printed fans can handle the power, but not the heat. :P
Last edited by Lynxman; Apr 05, 2018 at 10:08 AM.
Apr 05, 2018, 03:08 PM
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I just ordered a HET800-73-590. That should do the trick, maybe on 12S. With a heatsink. I don't want 6 kW, but 3 kW peak would be nice. I will adapt the fan to achieve the power I want.
Last edited by Lynxman; Apr 05, 2018 at 03:16 PM.
Apr 05, 2018, 06:52 PM
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Integrated fan to improve cooling.
Apr 05, 2018, 07:45 PM
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Hi Lynxman, very nice work !

When I was testing my 30mm fans I thought of doing the same thing (cooling fan in the center) but felt that
it wouldn't be of much value because the motor mount would be blocking any air coming through from the fan.
I thought that a bullet shaped nose would be more efficient by guiding the air over the can in a smooth stream
rather then hitting the blunt motor mount, although I could never prove it ...

Do you have a picture of your shroud ? It would be interesting to see how your doing it.
Apr 06, 2018, 09:53 AM
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The rotorstar RS700-500 motor is as efficient as the Neumotor at low power. I haven't tested it at high power yet but I expect better efficiency than the tiny Neumotor. Something must be off with the turnigy outrunner.

The impeller with integrated cooling fan gives the same result as my previous best impeller, so taht's good. Will try at high power with 12S later.

My housing has pretty big holes for cooling to the motor. The motor can suck in air from the duct airflow or from the front. If the integrated cooling fan impeller works well I will block off the ability to draw air from the FSA area.

I should add fillets to the vanes.
Apr 06, 2018, 01:15 PM
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Looks like I'm going to have to rethink my designs ....
Apr 06, 2018, 01:28 PM
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I think this will be the next housing if the test is successful.
Apr 06, 2018, 02:05 PM
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Got 4300 g thrust at 2400 W full throttle on 12S. I was wrong before when I said the cooling fan impeller was as efficient as the regular 13 blade fan. It's not. At least not on 12S. The previous run was on 8S, and I got better walues at 250 W and 500 W then than I did now with 12S. If I print a cone and glue to the back of the outrunner then that'll probably help a little. I'm looking forward to seeing how the HET inrunner fares compared to these outrunners.

I spent the whole pack at 1400 W without any heat issues, with a few long runs at full throttle. The two older 4S packs started going empty at 3600 mAh which is 86% capacity. They are several years old though so I might need new batteries soon.
Last edited by Lynxman; Apr 06, 2018 at 02:19 PM.
Apr 08, 2018, 04:20 PM
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If the L-39 is successful I think this will be next:
HEINKEL HE-162 GIANT SCALE RC TURBINE MODEL JET DEMO FLIGHT / Mega RC Airshow Göttingen 2015 (6 min 48 sec)
Apr 08, 2018, 06:28 PM
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I've started printing parts. Here's a main landing gear trailing link strut. It weighs 114 g as pictured and is very strong. Ball bearings in the knee. The gear door will hide most of the oil shock absorber.
Apr 09, 2018, 12:50 PM
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Looks like an old RC touring car shock, possible from an HPI car ?

Very nice design !
Apr 09, 2018, 12:53 PM
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It's a very cheap HSP touring/drift car shock. They come without oil so I will tune them and recommend an oil weight for the plane.

The one in the picture is one I stole from a car temporarily. I ordered some all black ones for the plane: https://www.ebay.com/itm/BLACK-Shock...4/272113528144


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