openrcforums

Hi,

I use the RPM sensor to get the RPM of my EDF and, once set the poles number I get a reading not true, around 20% of the real RPM when checked with an other system.
Where is the issue ? HW or software ?

MP

What RPM sensor? Some have a number of pole setting as well. You need to set the number on one and leave 1 on the other.

It is the FrSky S-Port RPM sensor where I set the poles number with 4 leds and the FW of the Tx is ErSky9xr where there is nothing to set.

There is a "Num Blades" setting in the "Telemetry" menu on erskyTx.
How many poles have you set on the sensor?

Mike

How many poles have you set on the sensor?

That's the question !

I believe the true RPM is given by my old Jeti Box associated with the MRPM sensor and, when set to 10 poles, I get around 24000 RPM
I checked the FrSky sensor equally with a Tx running OTX which give the same 20-25% reading when the sensor set to 10 poles.(according the level of the pack).

Mike you tell me I can set the "Num Blades" on ErSky 9X, right ?

Yes, "Num Blades" is in the Telemetry menu. Set this to 1 if the RPM sensor is set to the required number of poles.
It is possible you may need to set the number of poles in the sensor to half the actual number!

Mike

OK Mike, I dismanteld an old BL motor and count the number of coils, when I get 12 coils the pole number will be 6 or 12 ?

MP

https://helihack.co.uk/poles

Thanks kalle, very interresting; I suspect I have an issue with a 64mm EDF since I get only 19.000 rpm where it is claimed 3900 kv.

Is the Esc liable, is there a parameter to set.
The maiden flight - 800gr F22- was very slow, as expected...

Any idea .

MP