ORIGINAL: mdjohnson
Hello All
To those who have added opinions, thank you very much. I have been reseaching this a bit and have found that there is indeed a compromise in speed vs resolution. JR claims that their 8411 has 5900 steps but a transit speed at 6V of .22 sec. This is in direct contrast to the Hitec 7966 claim of .08 sec @6V. They however have a larger step to them which woud make sense as the quicker you move the servo it has to take larger ''steps'' for the desired travel. I have read that the quicker the servo, the coarser the stepping thus coarser resolution. The slower the servo, the finer the resolution and thus more ''step'' accuracy. This backs up the majority of opinions here and confirms the choice of many on the NSRCA equipement list. It is my understanding therefore that in pattern the resolution of the servo is more desireable than the speed as accuracy is tantemount and in 3D type flying the speed of the servo would be more desirable as radical and very quick control movements are called for.
Is this sound thinking? Anybody else?
Cheers
MJ
One thing to keep in mind is that the difference might not be as stark as the above scenario suggests.
What is not being taken into account is
servo arm length and control surface throws. A pattern plane control surface has a much smaller range of travel, and at the same time uses all (ideally!) of the servo throw available. Therefore the differences in steps are very minimal indeed.
I am using a pair of HS-5955TGs for elevator and rudder in a 2M plane, simply because I had them. I've got only 8 flights on the plane, but using the full servo range available (minus a small cushion for tweaking) they seem pretty precise to me. No shortage of torque!
Using a pair of Futaba 9551s on ailerons, and they are excellent as well.
My concern with the Hitec servos you mentioned above is the"HB" designation for Karbonite gears. Early on, I had several gear failures with HB-geared micro servos used in small electrics, where the gears shattered. I don't know if this is an issue with the HB gear trains with the standard-sized servos - or whether Hitec has "reformulated" the Karbonite material - but in any event I personally wouldn't use them in a glow or gas pattern plane, that's for sure. However, not having actually used the servos in question, I stand to be corrected on that opinion!
