Using bigger props than recommended by the manufacturer

General
1

Greetings and thank you for reading.

This post is with regards to using bigger propellers what fall outside of the manufacuteres recommended props size for a certain voltage/battery pack.

I have been using ecalc for my builds and it usuall is quite accurate. In my particular case I am using a 530kv 5010 motor, specs are in the screen shot below.

For my particualar build I am using 13 inch props on a 5 s pack which is 1 inch above what the manufacturer suggests.

So. How safe/unsafe is it to use bigger props. Would it just be better to use what the manufacturer suggest or can one safely use bigger props when ecalc shows that all parameters are within limits

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2

That data looks suspiciously like the junk RC Timer motors. If so good luck with any prop you use and don’t put anything of value on the craft. You get what you pay for with those.

3

Have not had many issues with them to be honest. But what about my question. Use any motor make you like

4

I have used all sizes of props w/o much regard to manufacturers published specs going by eCalc.

5

If not Rctimer which motors would you use?

6

Sunnysky or T-Motor 3508-580’s would probably do. What’s the take-off weight currently?
I had some LD Power Motors with 13" props that performed well but I don’t see those around anymore.
But, they will all be much more expensive than those RC Timer motors.

Actually those LD Power motors were 320kV and the props were 14" on 6S power so apples to oranges.

7

Manufacturers generally tested before recomending the spec. I usually stick to them. I had tried using an inferior motor with the same spec as one of superior. Performance, durability makes a big difference. Unless you are going to go into substantial testing both thrust, power consumption etc, why would you swich it?
Its important to look not just at thrust alone, efficiency ratio etc is just as important.

8

I don’t trust that chart either. I have never seen a manufacturer’s motor chart that looked even close to this. Its missing things like the grams of thrust per watt of power, and Kv ratings, leaving you to do the math. Taken by itself, motor size and Kv rating will get you in the ballpark for prop size. For example, something like a Tarot 4006 620Kv will swing a 13" prop on 4S all day long, and a TYI-Motor 5008 335Kv will swing a 17" prop on 6S. HINT: The bigger the motor, the lower the Kv, the bigger the prop… I have attached a spread sheet that will calculate flight time based on aircraft Take Off Weight, battery cell count and mAh capacity, motor/prop efficiency (grams of thrust/watts gW)
Calculate Flight Time.zip (1.2 KB)

9

i dont fly electrics currently but, when i did, i would start with the mfg recommendations and test with an ammeter/watt meter for the different props. props of the same size from different mfgers will probably require different pwr/amps. also, altitude/density altitude may make a difference. some pilots have a rule-of-thumb saying for higher altitudes: “IC engines-prop down; emotors-prop up”