Hey Y'all, what prop size Should I use on the Wattage, P-51 Reno Racer? Any advice would be great! lol Otherwise it's back to the ol' "Guess-and-cheak" method which is probably better suited for R/C cars rather than planes.

-Aerobirdbrain

May have some help for you Aero. I too am somewhat new to electric. Found a really good source for some of my questions. SR Batteries has about 54 articles, called volumes, about electric questions. Volume E11 is about prop selection and prop theory including matching prop and aircraft. I have quite a few of these volumes which cost $3.00 each, I ordered them by calling 631-286-0079. You can order as many as you wish and they cover most of the questions one may have.[img][/img]

One way to figure this out is to use a performance calculator such as MotoCalc, E-calc or this:

http://brantuas.com/ezcalc/dma.asp

Plug in your numbers, and try various props until you find one which produces the appropriate amp draw you need/can sustain. Should give you a ball-park figure - then you can tweak it on the test-bench or in flight.

Cheers, Phil

IIRC, the Wattage P-51 Reno Racer (looks nothing like a P-51, IMHO) has some weird low-pitch prop, like a 5-1/2x2. You ought to be able to purchase OEM replacements from Hobby People.

If you're looking for better performance, and have no idea what the numbers mean, all you can do is play the guess-n-check game with propellers similar in diameter and pitch to the OEM prop. Without changing the battery, motor, and/or gearbox, you generally have very little wiggle room as far as prop sizes go. Go much bigger in pitch or diameter, and you'll draw too many amps, causing the motor, ESC, battery, or any combination of the three to burn out. Go any smaller, and the plane won't perform as well.

That said, we'd need a few details about your plane to make any sort of recommendation. What motor does it have in it? What are the specs on the battery? What is the gearbox ratio, if it has one?