Throttle percent Futaba 8FG, headspeed?

[-G's]

Goblin 500 running a jive 100LV connected to a Savox 4750-1200 18t pinion and Pulse 45c batteries. As per a PM from Kontronick guy I have the jive programmed in mode 4 idle 1 55%, idle 2 60%, and idle 3 65%. I have also programmed the end points.
Running the Mr. Mel HS calc using 90% motor eff. I should be getting 2600-ish RPM @ 65%.
Head-speed today was tached @ 2486 zero pitch idle 2 65%.
Any ideas where my 100rpm discrepancy is?

[Wh1teAfr1can]

Originally Posted by -G's

Goblin 500 running a jive 100LV connected to a Savox 4750-1200 18t pinion and Pulse 45c batteries. As per a PM from Kontronick guy I have the jive programmed in mode 4 idle 1 55%, idle 2 60%, and idle 3 65%. I have also programmed the end points.
Running the Mr. Mel HS calc using 90% motor eff. I should be getting 2600-ish RPM @ 65%.
Head-speed today was tached @ 2486 zero pitch idle 2 65%.
Any ideas where my 100rpm discrepancy is?

are you letting the rpm stabilize at zero pitch before you lift off the ground?

[-G's]

are you letting the rpm stabilize at zero pitch before you lift off the ground?

. Yes; I center the col stick, take the heli out of TH and wait until the RPMs stabilize.

[Wh1teAfr1can]

so you have "calibrated" the end points? you should never do this. the Jive reads your throttle end points when you program modes. so you are feeding it a throttle percentage that is slightly off what its supposed to be.

go back to a normal linear curve 0-100 and set your end points back to 100/100 and program mode 1 then mode 4. then reset your throttle curves back to 55 60 and 65 and dont touch the end points and you will get the desired head speed.

[-G's]

go back to a normal linear curve 0-100 and set your end points back to 100/100 and program mode 1 then mode 4. then reset your throttle curves back to 55 60 and 65 and dont touch the end points and you will get the desired head speed.

Finally did it today exactly as shown in the video.........and...............2526. Only a 40 RPM increase?

Tached using heli tach for iPhone.

[Wh1teAfr1can]

i wouldn't trust those apps i had one that was 200 rpm under.

[GimpyGolden]

iPhone tach, motor Kv and efficiency are not exact. Expect up to as much as 10% discrepancy.
That said 40 rpm is pretty damn close.

[-G's]

iPhone tach, motor Kv and efficiency are not exact. Expect up to as much as 10% discrepancy.
That said 40 rpm is pretty damn close.

According to the online calc I should get 2600-ish so 2526 is 74 short. What I'm really trying to find out is if I should stuff a different pinion in it.
Is motor timing a possibly? Can it be adjusted with Progdisc?

Hopefully tomorrow I'll be able to get an independent source to verify HS.

Thanks again!

[-G's]

Hopefully tomorrow I'll be able to get an independent source to verify HS.

Update: Same tachometer as original measurement, clocked HS today at 2486 again.......

[MrMel]

It's within the tolerances, motors have +-5% tolerances in KV depending on production, different ESC's gives different KV due to timing, KSA mode etc changes.

Sum it up and the calc does it best it can, for many it's a perfect match but not for all.
Just adjust throttle curve to match.

[-G's]

Thanks MrMel!
Just for kicks I ran the calc again and it shows 2512 @ 65%. I'm not sure if I missed that or if I was looking in the wrong place. Anyway, I think a 19 or 20T pinion is in order.