flymeaway

My Feedback: (6)

When choosing a power system based on the watts per pound approach, do I look at the max watts a motor puts out, or sustained, or? I'm not going to be flying at full throttle the entire flight so I wouldn't be drawing as many watts say at half throttle compared to full throttle, which would take the watts per pound down.

Example: I'm looking at the E-flite Power 110 for the Wild Hare Edge that puts out a claimed 2000 watts. That equates into 200 watts per pound for a 10# plane. The average flight would draw less than 2000 watts, so is this not enough motor for what I'm after?

Sorry for the bad explanation. Thanks for any help.

DaveFlynn

Don't expect to get 2000 watts out of this motor. With a 9S Lipo and a 16x12 prop expect 1200-1600 usable. Great for sport, but a little low for 3D you'd be at or near full throttle most of the time.

Fliprob17

I typically use the sustained watts to calc. the lower end of the power window I am searching for. So for 3D, I use 150 watts per pound as the bare minimum, and using a 10lb plane, 1500 total watts (minimum) required. 170-180 watts per pound seems to be a good number to be around for a burst rate, and for pretty decent vertical. It is unlimited, but not space rocket quick.

jmohn

You will need to use a 10S setup to get 2000 watts. I have that motor in my KMP Stuka using an 8S setup and get 1620 watts using a 18-8 prop.


Jeff

mandtra

My Feedback: (29)

You also need to know that a motors rated watts. Is rated at the max cell count that can be used . If it's a motor using 5-10 cells and 1500 watts you can bet the only way to get the watts up is at the maxium nomber of rated cells.
For all out 3D you will need 175 watts per pound of AUW all up weight.

flymeaway

My Feedback: (6)

Thanks for the replies. Makes sense. I've only done one e-conversion with great success (4s2p A123 cells, Power-46 in a 1/5 scale Sig cub - flies scale and then some), so I'm a little lost when it comes to a plane of this size. when it comes to power set up. I'm not after 3D power since my flying style is more basic aerobatics/IMAC type of flying, but don't want this thing under powered or getting into the position where good flying requires too much throttle and therefore short flight times.

Since this plane will be powered by A123 cells, I'm thinking I'll have to go 12s1p in order to get the max voltage. I'm not stuck on the Power-110 either but am unsure of a better solution at this point.

jmohn: what's the weight of your Stuka and how does it fly on this set up?

DaveFlynn

Two things:
Running at full throttle all the time doesn't necessarily mean that the flight time will be short. If the setup is under prop'd (i.e.:3S1P 1550mAh, 30A ESC, 2814-900 motor, 8x6E) expect long flight times. I enjoy nice long flights, greater than 20 min. With this setup full throttle on the ground is only 12A and it's around 5A in the air. Ending up being only about 40 watts per pound in flight or 90 watts per pound static. The ESC is good for 5S Lipo, but it flies fine and a Cub would look silly doing 3D anyway.

Also, motors don't have a max voltage, only a max amps and max watts. If your ESC is rated for 50 volts then go for it. Select the voltage to get the rpm you want for the prop that fits the model best. Just be careful not to exceed the maximum amps for the motor, esc or battery or the maximum watts on the motor.