FE Calc and detongued Props

[domwilson]

Is there an approximation that anybody uses for detongued props in FECalc?

[ozzie-crawl]

yea i have always wondered myself how much difference it makes
just ordered last week a dx3s with telemetry i know some think the telemetry is a bit wanky but will be interesting to run a x series prop then detonge it to see the rpm difference, in fe calc you could probably try the m440 and x440, m645 and x645 see if there is much diffrence.
if i use fe calc on a 7xl 4s 2p with a x642 i get
amps 193
speed 91 klmh
watts 2276
this setup data logged with detounged x642
amps 77
speed 89 klmh
watts 1147
i dont think there is over 100 amps diffrent with a detounged prop
i think the fe calc has some issues

[domwilson]

I don't have the m series props in my fecalc. Where did you get those from?

[ozzie-crawl]

iam not sure dom, when i first loaded up fecalc it hardly had any thing on it, but found a update that added m series props, fiegao 580l motors and lipos
hopfully someone can point you in the rite direction

[ED66677]

I think above a certain limit FeCalc is out or over estimating, I take my 29" DF copy with 8XL/cheap 100A ESC/4S4900Rhino's/42mm prop as example, choosing Performance Mono, FeCalc says 120A, 1662Watt and 45mph, in reality (logged with EagleTree) I'm at 60A constant, approx. 1300Watt burst/90A burst, and close to 50mph!!!
To get some datas closer to what I have, I need to choose Performance Rigger in FeCalc, and just by changing COG I can be very close to FeCalc, so this demonstrate that estimating is not an exact science!

[ghostofpf1]

hope this helps
Steve

[domwilson]

Thanks