Need some help with figuring out amp draw
 

Alright,
I got all my equipment purchased, the only problem being is the prop and possibly having to change gears. I asked for help at another unnamed forum, and basically got no help. I need to know a range of props to get so im not pulling to much amp from the battery/etc

Here is my setup and I appreciate all the responses ahead of time


gws 400c
D gearing
3s kokam 1500mah 8c discharge
pixie 20

I need to know what size prop (range) i should be using to make sure im pulling the proper amps from the combo. Also, should i change gears? I am purchasing a whattmeter so i can fine tune it, but i dont want to buy 20 diffrent kid if props to see what one will work =/



Again, thank you for the help ahead of time


Sean

RE: Need some help with figuring out amp draw
 

That all depends on what kind of performance your wanting and how big your plane is, if you provide the following info it will make choosing a prop and proper gearing MUCH easier.

1. What kind of plane is it?
2. How much does it weigh?
3. What kind of performance are you wanting?
4. What is the normal operating voltage for your motor, 6v? 7.2? 8?
5. How much are you willing to spend on upgrades?

If your wanting good 3d performance everyone is going to want you to go brushless, and for a good reason!

RE: Need some help with figuring out amp draw
 

Thanks for the reply.

Im not looking for breakneck speed, its a 7.2v 400. So i should be fine drawing 10-12 amps. The plane is a gws e-starter. As for upgrades... Not really thinking im gonna upgrade this plane to much, but will upgrade when i master this one. As far as weight, im not really to sure, prob @ 20-21oz fully loaded.

RE: Need some help with figuring out amp draw
 

anyone? =/

RE: Need some help with figuring out amp draw
 

You can punch up the numbers using PCalc at www.flydma.com. Keep in mind that it's only a simulation, and isn't 100% accurate. It's best for getting RELATIVE figures.

I was a bit worried that you were trying to run a 6V Speed 400 on a 3S LiPoly. That wouldn't work for long. A 7.2V Speed 400 will be okay, though.

To tell you the truth, I don't have the foggiest as to what prop to use on this one. What's the actual ratio for a D gearbox?

RE: Need some help with figuring out amp draw
 

6.6:1 i believe

RE: Need some help with figuring out amp draw
 

Unfortunately, and I have Motocalc, the best way to find the "Best" prop is mostly trial and error. If you can tell me how many amps you want to draw I could tell you the best prop Motocalc says for that amperage.

But it appears a 9x6 prop pulls about 8.7 amps and seems to have the best balance of speed and thrust per Motocalc.

Hope this helps.