Head speed

[odieser]

Okay I am running stock gearing in my scale Hurricane with a Tonix Z20 980Kv motor with a 13T pinion
(front gear 42T rear gear 61T and 20T owb)
using the head calculators with 90% effeciency which I think is close I get 2000 rpm
Now for the question
I wish to run near to 1750 rpm's swinging 550 blades with my fuselage so I just lower my throttle curve to achieve this (near to 65% on the curve is 1750 or there abouts) or do I regear with possible a 50T front main and 13T pinion to achieve this at near 100% throttle curve.
Which is the more effecient ( as far a motor ) goes?
Thanks all
Mark

[MartinS819]

You'll want to re-gear instead of reducing throttle. Motors are most efficient at 90-100% throttle. Go too low and it may get hot or cause other things to run hot.

[bugdozer]

I've found the head-speed calcs are not really that close to reality. The best way to check your speed is with a tach. I have an inexpensive optical tach, $23. I cut a slot in a chunk of foam, put the tach in the slot and place it under the tips of the blades. Do this outside on a sunny day and you can see the readout on the tach without getting close to the heli and the spinning blades.

[istandalone]

i got one of those cheapo digital tachs, made by globee or something like that. it says you must be within 12" for an acurate reading. actually i've found that it's just as accurate at up to 32". that's almost three feet, and i feel much more comfortable at that distance. 12" was too close lol.