Mks hv-300 / 380

[callum]

Heya,

Came across the 300 and 380 Servo's from MKS.. There spec is quite good.. But.. Upon reading about the HV-300:

This is the servo for you if you are running flybarless and you want to run 8.4v - 12.0v on your servos. It is ideal to use more torque at the sacrafice of speed for flybarless because it is already so quick. This servo at 12v is so fast it could be a tail servo and with so much torque it nearly has enough torque in one servo to do the job of all three!


- Operating Voltage: 8.4V/12V
- Operating Temperature Range:
-10 to +60 Degree C
- Operating Speed : (8.4V): 0.18sec / (12V):0.13sec
- Stall Torque : (8.4V) : 26.9kg-cm / (12V) : 38.4kg-cm
- Motor Type: Coreless Motor
- Potentiometer Drive: Indirect Drive
- Bearing Type: Dual Ball Bearings
- Gear Type: Titanium Gears
- Case : Aluminum-magnesium alloy shell
- Connector Wire Length: 15cm
- Weight: 2.79 oz. (79g)
- Wire Length: 15cm
- Dimensions: 40 × 20 × 45 mm
- Deadband:Less than .001ms


Someone please help me out here.. How is 0.18 sec fast? DS610s @ 6v are faster, Or am I missing something?

[gorber]

They are saying that fbl is quick, so the servo doesn't have to be (but it does need to be torquey).

[callum]

Yeah, I know for sure it has to have more torque since the servo's are loaded more.

I doubt I would be able to crack-stick with those servos? Even if I was running FBL?

[gorber]

I have 352s on a flybarred Srimok and it is pretty fast (the speed is 0.15 sec/60 deg at the voltage I run). But I don't put the demands on it that you probably do.

[5exi]

Or you could look at the Turnigy HV servo's on hobbyking
There the same servo's just rebranded they even kept the no. The same.

Only problem with HV servo's you have to run them on at least the min voltage stated i'e 8 volts

Otherwise you won't gain anything,

[Andy from Sandy]

Using my own model as an example to go from full negative to full positive pitch on the blades the servo only moves about 30 degrees. So using them servos the speed would be 0.09 seconds. Doing a flip around the hover point would require -5 to +5 degrees of travel that is only half of my pitch range so now the speed is 0.045 seconds.

How much faster does a servo need to be for your flying style?

[callum]

Gah..

Just read that the MK HV Series is not compatible with Flybarless.

[gorber]

I saw some MKS servos fail on a FBL Srimok once. I don't know whether they were HV or not. I think it is the most expensive crash I have ever witnessed.

[Mark_T]

How much faster does a servo need to be for your flying style?

I'm surprised at you Andy, when did logic ever have a place in a debate fueled by unsubstantiated manufacturer performance claims?

[maderdog_1024]

What do your other "sponsored" pilots use in their MA55 helis ? That should give you an idea of what specs to look for.

[Andy from Sandy]

What do your other "sponsored" pilots use in their MA55 helis ? That should give you an idea of what specs to look for.

I am probably trying to teach granny to suck eggs but...

There is a point where a servo although appearing to have plenty of torque has a speed that cannot be attained when put under load. This is where a slower servo but with more torque ends up actually being faster when placed under the same load.

Just looking for a fast servo is not the whole story. By way of example the bls351 is slower than the bls451 but under a high load the 351 ends being faster.

[Smoothound]

I'm a bit confused to be honest as to why MKS would say that these particular servos are not compatible with FBL? Looking at the specs I can see no reason why not??

[maderdog_1024]

Im going to use the MKS/Turnigy servos on a 90 gasser and run them from a 3s lipo. It really needs lightning fast servos for all the insane 3D its going to do. lol

Would be interesting to get speed at full load figures for servos then you would have a more accurate measure.

[Mark_T]

I'm a bit confused to be honest as to why MKS would say that these particular servos are not compatible with FBL? Looking at the specs I can see no reason why not??

I'll see if I can find the link where this was explained, but if memory serves, the problem was that the motor was not up to the sustained work load.

This is the other problem with these wonderful specs we see on servos as they don't take account of what will happen once the servo is worked hard and has got hot.

As Andy has shown, the real difference between fast and very fast servos is absolutely tiny when you consider each movement as being a command to start, move and a stop over relatively short distances with probably as much time in the start and the stop as the actual movement.

Also I strongly suspect that when looking at quoted torque ratings we are only seeing the static holding figures, not the dynamic torque figures. The ability to hold accurately to the set position is important of course, but the ability to move under load to a new position accurately is what we should be more interested in.

[maderdog_1024]

Have a look at hobbykings new Mi Range of servos they are fast according to the specs

0.08 at 4.8v and 0.07 at 6v