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Old Feb 28, 2013, 11:15 AM
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New GEMFAN E-Propeller VS GRAUPNER E-Prop - Comparative tests

Having discovered Flyduino's GF E-Propellers, copy of GRAUPNER E-Props, I have wanted to know how student compares to master.
GF 10x5 being unavalaible at the moment, I have tested 11x5 props.

Test parameters are the following:
Turnigy Park480 850KV motor, 40A ESC, Watt's Up Wattmeter, Turnigy Servo Tester, 4Ah 3S battery, Turnigy Micro Tacho and 5kg (10g accuracy) scale.
Two levels, half throttle (1.5ms) usually used for hover and full throttle (2ms) for max thrust.
Test bench is basic and measuring devices are not the most accurate, but the set is suitable for comparative tests.

Physical comparison between Graupner and Gemfan:
Shape: Similar, animated GIF below.
Graupner is GRP reinforced, GF is pure polymer.
Bore: Graupner 8mm, GF 6mm
Weight: Graupner 16.32g, Gemfan 12.13g
Balance: Graupner 0.02g (0.12%), Gemfan 0.01g (0.08%)
Graupner is less flexible than Gemfan. Animated GIF below.
Prices are very different, Gemfan cost less than $2 each, including hub spacers.

Below is what I have got.
Student has well learnt from master, performances are absolutely identical.
These props, and motors, should be suitable for a 1800g quad.







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Last edited by Mortimer; Mar 06, 2013 at 08:30 AM.
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Old Mar 06, 2013, 08:23 AM
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GemFan E-Propeller 10x5 are now available.
Comparative tests are below.
I have been surprised by the results.
Although being more flexible, GF performs identically to Graupner.

Shapes are similar.
Graupner is GRP reinforced, GF is pure polymer.
Bore: Graupner 8mm, GF 6mm
Weight: Graupner 12.52g, GF 9.06g
Balance: Graupner 0.04g (0.3%), GF 0.01g (0.1%)
Price: GF cost 4.80 euros the set of four ($1.60 each with adapters)



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Old Mar 06, 2013, 08:39 AM
Mmmmmmm!
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This is great news!

Gonna order some ASAP and use on my F450.
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Old Mar 06, 2013, 08:45 AM
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Ah, about time this crap got cloned. Now all those snobfaces who paid $50 per prop for this junk that was made in same factory can go cry in a corner.
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Old Mar 06, 2013, 08:46 AM
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I am just curious why you would expect different results from the exact same prop??
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Old Mar 06, 2013, 08:51 AM
Mmmmmmm!
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The prop is more flexible, so I don't think it's unreasonable to expect different results. But whatever, they're close enough. I don't want to use the stock DJI props on a quad I use only for bashing because they WILL break, but I don't want to use Graupners either because they're hella expensive. This should be perfect!
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Old Mar 06, 2013, 09:14 AM
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The great question about using clones in real life is: will you get the same minimal amount of vibration right from the box? This and resistance were the main selling point of Graupners, not efficiency...
This is not dependent only to the good balancing, but also depends on the prop stiffness.
May I suggest to mount a FC on the test bench and plot the vibrations graphs for a Graupner and a Gemfan ?
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Old Mar 06, 2013, 09:17 AM
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How much do the propellers weigh? And also, what about the vibration? Graups are known for helping to rid of jello.
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Old Mar 06, 2013, 09:19 AM
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Quote:
Originally Posted by renatoa View Post
May I suggest to mount a FC on the test bench and plot the vibrations graphs for a Graupner and a Gemfan ?
No prop comes from the factory balanced. So if he did "vibration" tests, they would not be identical to other props sold to other people.
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Old Mar 06, 2013, 09:31 AM
Mmmmmmm!
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I personally don't care much. I used brand new Graupners on my F450 and they didn't help much. The frame is a jello machine, but it's fun as heck to fly so I'll use the Gemfans on it. I'll spend SOME time on balancing them, but a bit of jello is OK in this kind of footage.

I do realize that most people will use these on AP rigs and whatnot. But they'll spend a lot of time on balancing them so they should be fine.

DJI F450 - KK2 + 10x5 Graupners + 4S = Fun (3 min 12 sec)
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Old Mar 06, 2013, 10:11 AM
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Quote:
Originally Posted by v00d0o View Post
How much do the propellers weigh? And also, what about the vibration?
Look above.

10x5:
Weight: Graupner 12.52g, GF 9.06g
Balance: Graupner 0.04g (0.3%), GF 0.01g (0.1%)

11x5:
Weight: Graupner 16.32g, Gemfan 12.13g
Balance: Graupner 0.02g (0.12%), Gemfan 0.01g (0.08%)
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Old Mar 06, 2013, 10:17 AM
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Woops glanced over that
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Old Mar 06, 2013, 10:23 AM
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I'm not trying to rain on your parade here Mort. I just don't see that big of a difference in these tests other than stiffness.

How about a test with carbon fiber gem fan 10x5 versus carbon/nylon and full nylon gem fan 10x5??
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Old Mar 06, 2013, 10:43 AM
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Don't forget the big one... Price.

You get pretty much the same kind of performance, lift-wise, as with the Graupners.

But you get 4 of them for 5 euros, as opposed to just ONE Graupner prop for just over 10 euros.
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Old Mar 06, 2013, 10:58 AM
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I recently switched from Carbon/Nylon 10x4.5 gemfan to full carbon fiber 10x4.7 gemfans. I am in love with them, here's a video I made when I first switched. I still have to balance them though.

Maiden on Carbon Fiber Props (2 min 40 sec)
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