figuring out Horse Power
 

Could some one tell me how to figure out roughly how much Horse Power my set up is...

My set up is a 1520 on 5s if that helps.

You will need a data logger to get an accurate idea. The power output will largely depend on the batteries you run. Brian's calc is also a handy tool. IIRC 1HP=746w.

Have a play around with BrianG's calculator

http://www.scriptasylum.com/rc_speed/_top_speed.html

Converts watts into HP

I played with the calc a bit...and it says that I should have around 3HP. I thought w/the 1520 on 5S that I would have a bit more

i have a cheap turnigy logger that works pretty good, was about $30 shipped. my favorite part is the backlite on it. i think it samples at like 10 times a second, so you will miss the larger spikes but so far ive used it in a number of different setups (2-6s) and it gives decent info. as stated above 1hp=746 watts. could get pretty close doin some math i suppose, but how close its hard to say.

You really need a logger for any level of accuracy, but you can get a rough estimate:

1) Calculate average current draw by using runtime and amount of Ah put back into the pack. Example: If you are getting 15 minutes on a 5s 6Ah pack, that's 24A average current (6Ah*60)/15 min.

2) You can probably assume ~3.7v/cell average voltage. Using the same example pack, that's 18.5v.

3) Multiply the two to get watts. Divide that by 746 to get HP. So, that's 444w, or 0.59HP.

You can very roughly estimate peaks by assuming current spikes ~6 times the average value. You can assume voltage will drop to ~3.4v/cell on those spikes. Then, repeat step 3 again. For the example numbers above, that would be 2448w, or 3.28HP.

Peak HP specs are just for bragging rights because those spikes are so short. And really, it's the torque on these motors that is what is so impressive.

I agree w/you Brian about the torque..The reason for this thread to begin with was that a co-worked asked me how much horse power my set up was producing and I wasn't sure..

There was a great thread back along with this kind of discussion, and lots of great mathes/ formulas were posted- I happended to make a note of them for future bragging purposes :mdr:

Torque (ft/lbs) = 1352/kv x amps/192

Torque x RPM/5252 = Horse power

Watts = volts x amps

HP = watts/746

Torque = 1352/ kv x amps

Should be correct :smile:

Thanks Neil...will bookmark this page for future use!