TAftonomos

My Feedback: (1)

To me, the fun of a foamy is the economy of it all. I want the big foamy, but don't want to spend $150 on a motor and ESC when I can get cheap ones from HK. Problem is, I'm so new to electrics, I don't know what to look for.

I think watts=power, so I've been looking at motors in the 600 watt range. I'm confused by the KV rating, what batt to run, etc..

Can someone help this noob?

rmenke

My Feedback: (13)

Grasshopper:

We need more info to begin to help. What type of flying intended, sport or 3D? What is the weight of the airplane you want to yank around? In general:


A 600 watt motor will fly a 6 pound sport airplane, basically 100 watts per pound.
A 600 watt motor will fly a 3 pound 3 D airplane, basically 200 watts per pound.
I am greedy and use 300 watts per pound in general, overkill for sure.
Most modern manufactures are smart enough to give you motor recommendations for what they are selling, and recommend their brand of motor. Its a starting point, look up the specs of the recommended motor and esc and find something at HK in the same ballpark. I usually add some watts to the sizing of HK motors, generally they do not perform as well as the ad shows, but not always true.
KV is the rpm the motor will achieve per volt. Sport and 3d flying, something around 1,000kv to 1,300kv. If using 11 volts X 1,000 kv gives you 11,000 rpm in theory. wanna go faster, use a higher kv motor, or a lower kv if its to fast. (Or a higher voltage battery)
Yes, volts X amps = watts or power, or work. Yes, a experienced flier can calculate his power needs fairly closely.
After all the above, we come to reality, what the system will actually do. To find out, you need to purchase a descent watt meeter. You can then tell whats really going on with that motor, prop esc and battery. The watt meeter will save to money, time and grief and should be considered a necessity of life. One size in prop pitch or length can make the difference between good performance, or a burned up system. Feeling the motor, esc and battery for heat is not the way to keep things living and performing. Usually you have a burned out system and a crashed airplane if you rely on the touch system. Do things right, the cost of the watt meeter will probably pay for itself in your first use.
A properly balanced system will only be warm to the touch. When hot, something is wrong.

There are exceptions to almost everything I said above. Wanna go fast? To get to 150-200mph everyting in the setup will usually get hot, requiring quality equipment. $$$= speed. ENJOY

Dr Kiwi

These should spin a decent size prop on 3s to get you lots of thrust... but if you need speed then you want a higher Kv.


http://www.hobbyking.com/hobbycity/s..._1000Kv_/_605w

http://www.hobbyking.com/hobbycity/s...8_900Kv_/_770W