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Old Jun 02, 2012, 01:59 PM
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Originally Posted by Aeroplayin View Post
We went through two Turnigy motors in Tom's PA 260 two years ago ... one of them came with the plane when we bought it from a friend ... before we decided that cheap motors were just too expensive. It is not to say that putting very small props on them and running them up to max RPMs in straight and level flight will have the same affect, but we have always sought the bigger prop option, and the cells, and the motor, to accommodate 3D and extreme aerobatic maneuvers.

In flying IMAC sequences, larger props provide more consistent velocity at all attitudes than smaller props, which is important in scoring, and bigger props provide more low RPM torque, and more airflow over control surfaces that are in full departure, so it has always been the direction we have gravitated.

To spin a 24x10 prop on our 50cc airframes between 85 and 88 inches, we went to a very expensive Hacker, but I feel in the long run that the investment will prove to be worth it, just like the Motrolfly has been with the 48 and 60. I actually have a NIB Turnigy that I bought two years ago but never mounted it on an airplane because I had virtually no faith that it would do what it was intended for, or last through any real extreme aerobatic flying for any amount of time. I don't like bashing products, but seeing this only reminds me how passive you really have to be with HK motors. The Plush, K-Force, and Superbrain ESC series, on the other hand, have been as good as, or better than, anything I have used on 48 to 60 size airframes.

I have enough trouble trying to keep from dumb-thumbing a great airframe into the ground, and I donít need any help from motors like this. If anyone is interested in paying the shipping, Iíd be happy to send this HK motor to you for free just to keep it from finding its way onto one of my airplanes in a weak moment, or to keep me from giving it to a club member and having to hear the dark stories from them later.
I'll take it, PM sent
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Old Jun 02, 2012, 04:58 PM
-= GYRO =- is offline
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Originally Posted by stgdz View Post
You are going to really like those combos, way better than the sunnyskys
Flew my motorlfly's today. Not as much punch, power, or speed as the sunnysky motors, BUT the motrofly motors ran about 30 degrees COOLER, and at just about 7 or 8 amps less than the sunnysky motors.

I'm happy with them, as they'll allow me to fly hard during the hot summer months... but I think I'll miss the extra oomph I was getting from the sunnysky motor.
Old Jun 02, 2012, 05:58 PM
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Wow that's the complete opposite that I had with the sunny sky 2820 800.


The things was a complete dog compared to the motroflys. You never were able to post rpms with yours, the rpms on mine were way low for power output.
Old Jun 03, 2012, 01:38 PM
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12x6 800 vs 13x6.5 600


The top speed of these two should be the same rite? My laser felt slower on 4s than my 5s mxs and extra.
Old Jun 03, 2012, 01:48 PM
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Originally Posted by stgdz View Post
12x6 800 vs 13x6.5 600


The top speed of these two should be the same rite? My laser felt slower on 4s than my 5s mxs and extra.
Speed will be a direct result of prop pitch and RPMs, and RPMs depend on volts, Kv, and Kv efficiency with the specific prop specs, and volts will vary over the course of the flight envelop. Probably more variables too, but that's why I always read RPMs and volts. It tells me everything I need to know.

If the 600 is a Motrolfly and the 800 is something else, then it's tough to even speculate.
Old Jun 06, 2012, 04:11 PM
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What was the verdicts of the Xoar 13x7 PJN on the 750Kv motor? Did we see data on this combo yet? looks like the L ratings are clear right through 10,000 RPMs.
Old Jun 07, 2012, 08:03 AM
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Originally Posted by Aeroplayin View Post
What was the verdicts of the Xoar 13x7 PJN on the 750Kv motor? Did we see data on this combo yet? looks like the L ratings are clear right through 10,000 RPMs.
I'm interested also, as I'm looking for a little more oooomph out of my setup
Old Jun 07, 2012, 08:59 AM
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I just did some digging and found this from past data. It is probably Steve's numbers:

8971 RPMs @ 79.8% KvE and 64A

I think I have one in prop box and if I do I'll try it on the 638Kv motor on 5S too. If angular momentum has anything to do with motor durability, which so far seems to be the case, then I should be in the clear. I was only getting 9540 RPMs with the 13x6.5e APC.
Old Jun 07, 2012, 09:10 AM
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Yeah, Steve posted the numbers on the 48 Edge thread... Thanks, Steve.
Old Jun 07, 2012, 09:22 AM
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Motrolfly DM2820
Kv: 600Kv
Prop: Xoar 13x7 PJN
Cells: 5S
RPM: 8800 RPM
Watts: 720W
Amps: 40A
Airspeed: 58.3 mph
Static Thrust: 2.81kg

These were my numbers
Old Jun 07, 2012, 09:45 AM
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Originally Posted by stgdz View Post
Motrolfly DM2820
Kv: 600Kv
Prop: Xoar 13x7 PJN
Cells: 5S
RPM: 8800 RPM
Watts: 720W
Amps: 40A
Airspeed: 58.3 mph
Static Thrust: 2.81kg

These were my numbers
I've got them in my chart too... I'm going to try to add a column with the value for angular momentum if I can get the weights for the Xoar props like I have for the APC, and then publish the chart here. So far, I have 19 rows of data for Torque, Motrolfly, and the Sunny Sky on 12x6, 13x6.5, 13x7, 14x7, 14x8.5, and 15x6 prop sizes... from 600 to 820 Kv.
Old Jun 07, 2012, 11:15 AM
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Thanks for the work Aero... these are helpful.
Old Jun 07, 2012, 11:38 AM
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I'm really glad to say that everyone here has contributed, and Steve and a few others put a few motors at risk to deliver some interesting data that begins to show where the edge of the envelop is, so we're all in this together here... but thanks.
Old Jun 07, 2012, 11:45 AM
GetSome! is offline
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I appreciate everyone making the effort. I have learned a lot
Old Jun 07, 2012, 12:44 PM
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Totally... I didn't mean to leave out all the people that have contributed to the testing. Thanks


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