stealthdragonb

.

blvdbuzzard

You are running (2) 4s 5800's / 8s 5800mah battery. what size prop?

If you run it with one battery, do the number change?

I used [link=http://www.s4a.ch/eflight/motorcalc_e.htm]THIUS CALC[/link] to see rough number. That motor with 8s battery, swinging 20X8 APC "E" prop pulls 80 amps and gives 307 ounces of thrust.

Buzz.

stealthdragonb

.

blvdbuzzard

I ran the motor again with the 8s, 15X10 give 196 ounces at 41 amps. The 14X12 has even lower amp results.

If you have one on hand, try a larger prop and see what happens. When I was messing with the calc program, I went up to a 20X8 prop.


Buzz.

stealthdragonb

Thanks for your prompt replies,
Yeah I get similar results using motocalc but when I try and test the actual motor with 8s, the 14x12 given only a current draw of 26A and the 15x10 gives only 15A. This is really surprising given the fact there is a huge difference and something is definately wrong somewhere. This motor can handle up to 95 A and given the fact it is only around 20A draw it makes the plane very hard to fly. Is there any particular setting in a turnigy superbrain 100A ESC which may be limiting this?

blvdbuzzard

I am not familiar with that ECS. To me, it sounds like you are under propping the motor and not getting it into its efficient wattage area.

When I tried to run the 15X10 prop, the calc program flagged it as stalling and not creating enough lift. Try a larger diameter and less pitch. If you do not have the prop clearance, how about a 3 blade prop?

These are WAY pricey!!!!!!!!!!!!!!!!!

http://www.valleyviewrc.com/estore/x...ller-18x8.html

But I ran the numbers through the calc program and got 294 ounces of thrust, 18 3/4 pounds, 8.3 kilo's It will even handle a 18X8 4 blade prop.

If you are using a watt meter and only getting 20 amps draw, go larger on the prop a little to see if the amps go up?

Buzz.

stealthdragonb

I tried a 17x12 APC prop today and got 28A current draw which is an improvement from before and most likely will increase the amount of current draw as propeller diameter is increased. So obviously there is an improvement but still doesn't explain why it is much lower than the expected results. Is it possible to explain why these results are so low and whether it could mean that I need to replace the ESC?

blvdbuzzard

Now as I re-read this thread, I see I have not asked how you are measuring the watts and amps? Are you using the ESC or are you using a watt meter? If it is the ESC, I have read that the wrong timing can give strange results?

Do you have a watt meter to use as a test to compare the results? How about a tach? That way you can see the RMP the prop is doing.


Buzz.

stealthdragonb

Hello,
I am using a eagletree power panel which is failry accurate as I have also got the same results using another wattmeter. By the way I think I am close to figuring out the problem. I plugged the throttle wire comming from the ESC to the rudder channel of the jr receiver and found that the 15x10 propeller was now drawing 23A opposed to 15A. So I am assuming the JRdsx9 transmitter may be limitting the full throttle speed. Any advice on this? Also do you think the turnigy superbrain 100A ESC needs to be configured somehow to recognise the full limits of the throttle stick?
Thanks!

blvdbuzzard

It may need to be calibrated to the radio. There should be directions on calibrating it. Take the prop off the motor. Turn on the Tx, move the stick to full throttle. Plug in battery for ESC, It should give a series of beeps, lower throttle, anther series of beep. Then it should initialize. That is the way a couple of mine did it?

Are the EPA setting on the Tx set to give full throttle?


Buzz.

stealthdragonb

okay, I'll try that today. What is the EPA setting on the Tx, I checked the throttle curve and it is linear going from 0% an finally to 100%, is this what you mean?