It's interesting that the BLS255HV and BLS451 servos have the same specs at 6.0V:
Speed: 0.10 sec
Torque: 142 oz • in
The BLS255HV servo specs at 7.4V are:
Speed: 0.08sec/60 (7.4V)
Torque: 12.0kg cm (7.4V) ==> 166.6 oz • in
That's an improvement, but it's not a huge improvement.
So when I saw the Futaba BLS157HV specs, the torque numbers floored me:
Speed: 0.11sec/60 ° (7.4V)
Torque: 37.0kg • cm (7.4V) ==> 513.8 oz • in (!!!!)
Speed: 0.14sec/60 ° (6.0V)
Torque: 31.0kg • cm (6.0V) ==> 430.5 oz • in (!!!!)
Shouldn't these be the ticket? Or, is this just a case of pure overkill, with a servo that has massive torque -- which in turn may need massive amps? I mean, there must be a torque value that's high enough to move the swash for even the most demanding moves. For example, there are a lot of guys out there using BLS451 @ 6V on 700-class helis. While these servos don't have eye-popping specs, the pilots that use them aren't complaining that the heli isn't doing what it's told.
So my questions are (and these are for a 700-class FBL heli, flying hard 3D):
1) what really is the minimum amount of torque you need for "good" heli response? For lack of a better explanation, I guess "good" means that the heli is doing everything you're telling it to do, without ever feeling that the heli seems "disconnected." I reckon that if you installed some servos rated at 75 oz-in and 0.25 sec on any 700-class heli, it wouldn't fly so well. LOL!
2) what's the minimum servo speed needed (for cyclic servos)? For example, I know lots of guys that prefer using the Futaba BLS351 (206 oz • in and 0.13 sec @6V) over the BLS451 as a cyclic servo. It seems they believe the higher torque outweighs the slightly slower speed.
Matt, what do you think?
