Increase your planes performance using the Watt Meter

[@dagobertosalazar]

Great video and a great tool! I just want to add that these tests should be done with a FRESH battery EVERY TIME, because drawing charge from the battery will yield a lower voltage, skewing the results of both Amps and Watts.

[@SteffenRC]

Yep.. Also the amps will usually be lower when the plane is flying verses static testing...

[@ModelAV8RChannel]

Invaluable tool for an electric pilot. Nice Will!

[@SteffenRC]

You know it... Thanks

[@jollyroger2226]

Thanks for the good info Will.

[@SteffenRC]

You bet!

[@mikenadler7118]

Thanks for the valuable information, here and your other videos.

[@SteffenRC]

Glad you like them!

[@livegood9876]

Neat tool and good video Will.

[@SteffenRC]

One more tool you'll need...

[@SlowFlyer85]

Will great info I have all the stuff too and should be using it more too good video

[@duncanmartin2626]

Surely it can't tell you anything about efficiency unless you are also measuring the force that is produced? I want to try to do that using a fishing weighing scales so I don't have to put anything in front of the prop, but I'm not sure how to rig everything up

[@txkflier]

I use watts/lb to determine the overall performance. It takes pitch speed (rpm x pitch / 1056) to move the air fast enough to pull the plane at at least twice its stall speed. Thrust is great for going vertical, but it takes pitch speed to pull/push a plane thru the air. You can move a large column of air slowly or a small column of air quickly, but you'll probably want something in between. I like props with a diameter that's 1.5 times its pitch; e.g., a 9x6, 12x8, etc. The blades won't be stalled at zero airspeed, and the blades are short enough that the motor doesn't have to work too hard to turn it.

[@duncanmartin2626]

@@txkflier W/kg is a good way of ensuring your plane has the performance you expect, but it is making assumptions about how the electrical energy consumed is used. The video is talking about how changing a prop can increase efficiency, but efficiency is about using the energy for the best effect. Without knowing what is happening to the air, drawing more Amps might be less efficient. If comparing a 10x7 and an 11x6, is more W consumed better or worse?

[@txkflier]

@@duncanmartin2626 The longer the blades are relative to the pitch, the less efficient the prop will be. A full-scale plane with a constant speed prop will go farther in coarse pitch than it will in fine pitch.

[@SteffenRC]

Thats where eCalc website helps determine which power system for your plane.. If you are building and designing planes/power systems, checkout eCalc....

[@Stirling_RC_Videos]

Great video. I'll have to get one soon. So, the more amps pulled, the shorter the flight but more power and speed? Is that correct? What is the impact on the ESC and motor of the higher amps? How many amps is too much?

[@SteffenRC]

There are trade offs. In this case the Stock 11x7 wasn't as efficient as the APC 11x7. So, I actually had more power and similar flight times. The speed and power were increased, but since I don't need to be at full throttle all the time it was a wash. If I was really pushing the system with a long prop, then typically the speed/power would be more and less flight times. I don't like to see a AMP draw over the ESC max. Also, motors have a max AMP/WATT too. So, you gotta watch that.. There is a wonderful website called eCalc. It's great for sizing a power system.

[@imacenaveen]

The amp draw seems reasonable because I have DYS 3536 1250 kv motor running 10x7 APC prop that draws ~50 amps which i think is too high, Any idea why ?

[@txkflier]

No-load rpm = 11.1 x 1250 = 13,875 rpm Loaded rpm = No-load rpm x 80% = 13,875 x 80% = 11,100 rpm Pitch speed = Loaded rpm x pitch = 11,100 x 7 / 1056 = 73.6 mph Watts = 5.33xE-15 x rpm^3 x Diameter^4 x Pitch = 510.3 watts Amps = Watts / Voltage = 510.3 / 11.1 = 46 amps If I add 10% for motor loss, the watts is 510.3 / 0.9 = 567 Watts In. And, 567 / 11.1 = 51.1 amps. So, there you go..

[@imacenaveen]

@@txkflier Thanks for the explanation, The equations will help me optimize my setup.

[@SteffenRC]

Sounds like Txkflier got you covered... Appreciate you watching..