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Old Oct 18, 2012, 03:14 PM
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Quote:
Originally Posted by Bruce Abbott View Post

Drive System: GWS EP5030 (ba); 5x3 (Pconst=1.23; Tconst=1) direct drive.
Bruce, as I understand, the figures above are for a GWS EP5030, not a HD5030.
By the way, is there a difference between the two w.r.t. the thrust at a given
rpm?
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Old Oct 18, 2012, 03:26 PM
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Chattanooga, Tennessee, United States
Joined May 2003
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Those props are one and the same....GWS only make one 5"x3" prop and its shape is essentially the same as larger GWS HD props (say, 6x3 GWS HD and 7x3.5 GWS HD [top row].... and 8x4, 9x5, 10x6 etc...some sellers call these DD just to confuse us)... there are small paddle bladed GWS props which are the only GWS props which I call DD (say, the 4x2.5 left end of second row down)... and their RS series props (like the 6x5 GWS RS in this picture) which are somewhat comparable to APC SF in blade shape.
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Last edited by Dr Kiwi; Oct 18, 2012 at 03:35 PM.
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Old Oct 19, 2012, 08:15 AM
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Thanks, Dr. Kiwi, that's an useful piece of information which should, but it's not available easily from the manufacturer and the resellers.
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Old Aug 06, 2014, 01:26 PM
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Quote:
Originally Posted by Bruce Abbott View Post
Compare this to ssatoru's test data in the thread New 5 gram outrunner/ unitedhobbies HXM1400-2000, Extrapolating from my own tests of the EP5030, Motocalc predicts 73g static thrust at 9400rpm. 54.2g corresponds to about 8100rpm.

Either your motor is running significantly slower then it should, or your thrust measurement is inaccurate (perhaps a little of both?).

Code:
Motocalc In-flight Analysis
Sea Level, 101.3kPa, 20C

Motor: HXM1400-2000 (ssatoru); 2020rpm/V; 0.35A no-load; 1.55 Ohms.
Battery: Test Lipo (100C); 2 cells; 10000mAh @ 3.82V; 0 Ohms/cell.
Speed Control: Castle Creations Phoenix 10 (cc); 0.013 Ohms; High rate.
Drive System: GWS EP5030 (ba); 5x3 (Pconst=1.23; Tconst=1) direct drive.
Airframe:  None.

AirSpd  Batt Motor Motor  Input   Loss MGbOut MotGb   Prop Thrust
 (m/s)  Amps  Amps Volts    (W)    (W)    (W) Ef(%)    RPM    (g)

   0.0  1.91  1.91  7.61   14.5   7.27   7.24  49.9   9390   72.8

After almost two years, I have some time for more detailed measurements.

I measured the rpm with a small 2s Nanotech battery and I get about 9500 rpm with a freshly charged battery, dropping after a few seconds to 9200 rpm.
So, it seems the rpm is within the expected range.
Probably it's my thrust measurements which weren't accurate.
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Old Aug 17, 2014, 01:04 PM
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With a GWS DD-4540 and a fresh battery I get 8800rpm max falling to 8600rpm after a few seconds.
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Old Aug 17, 2014, 07:43 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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The change in RPM is likely due to the voltage falling and then fairly well stabilizing. It is normal for a pack voltage to fall continuously as the capacity is used up. Cells start out at about 4.1V or so under load and are pretty well used up when you get down to 3.7V or so. That assumes the pack is of decent quality and size of course.

If the heat is building up fast in the motor that can be a factor in the RPM drop too.

Jack
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