Brushless Whoop Ducted Thrust Test (1102 15000KV motors)


So my Flex RC 1102 15000KV Brushless Motors and other parts finally came in. Since a bunch of you guys were looking into brushless whoops (and some were particularly interested in these specific high KV motors), I thought I’d add my 2 cents, so you can decide whether or not to buy these motors. (If you do decide to buy, please click the link in the YouTube video to give me some cash for my addiction to this hobby!) :grin: (No link here though.) :+1:

Motor Build:
Decent. A few of the windings were not perfectly wrapped around the stator. I’m probably just spoiled by my Emax 1106 motors. Haha!

Flex RC 1102 15000KV brushless motors (weight just a bit more than the 0705 motors, but with real bearings and more thrust!!!)
Eachine 1535 4-bladed props
Split (3S) to 1S 450 mAh 45C lipo
TinyFish FC + ESC Stack

Here’s the video:

I found that ducts barely increase the efficiency of the motors. They do decrease the Amp draw slightly. I do plan to do a quick test when my 1535 KingKong triblades arrive. I also plan to decrease the tip clearance from 1mm to 0.3mm to see if that has any effect, since I read that the added efficiency from a ducted prop decreases dramatically with increasing tip clearance.

I reran this test without video for a 2-bladed Eachine 1535 prop in the full duct, and I got 2 grams less thrust with 0.6 A less Amp draw. Maybe worth it?


Good work, @Imozeb! :smiley:

I plan to run my 1102 15,000KV on 2" props. Unfortunately, USPS lost my 16x16mm ESC order from BG. So I had to reorder an ESC from RMRC. It’ll be a few more weeks until I can try for myself.


This is the theory behind:


In my subjective testing I found the KK 1535 to perform much better. Way more efficient, around 30 seconds more flight time after I switched to those triblades. For some reason they are pretty much constantly out of stock, fortunately (for me) I’m one of the causes for that. :smiley:


I ordered some KK1535 from xtInte and I plan to do a quick thrust test on only the full duct when I get home today.

I’ll let you guys know the stats soon.


Additional stats:

Full Duct KingKong 1535 Prop - 50% throttle - 8g thrust - 0.8 amps - 80dB noise

Full Duct KingKong 1535 Prop - 100% throttle - 26g thrust - 2.83 amps - 108dB noise

For comparison to a 6mm Tiny Whoop:
2 blade - 100% throttle - 80dB noise

So judging by this data, my indoor whoop is going to generate a lot more noise at full throttle. (Though it should hover at less than 50% throttle)

The KingKong props generate less thrust at full throttle, but also less amps and noise. However, the thrust and amp draw is comparable to the Eachine 1535 cut 2-blade props (though they generate less noise which is a big plus for an indoor brushless).