2048

[jbiter]

Does anyone know if it matters which digital servos to use with the 14MZ. In other words, can all digital servos see the 2048 resolution?

Jeff

[Russ McC]

Hi Jeff,

I think all the servos see the 2048, there are some “suggested” servos and 9252 is not on the list but I can definitely see/feel the improvement in resolution using 9252s.
Suggested servos
9154
9151
9250
9255
These are all digital servos and the 9250 has been around for a long time, well before the 9252. The 9250 used to be the favored high speed digital tail servo before the days of the 401 & 601 and is called for general heli use. I have seen a half dozen of these servos fail on the tail so I would not recommend this for any heli use, but maybe they have improved it’s reliability, I don’t know. So what I’m getting at is that if they suggest this fairly old digital servo then it would be reasonable that the newer and probably all the digitals will be good and be improved be 2048. I would also think that even the non digital servos would be improved by the 2048 :glasses2:

[jbiter]

Thanks for the reply.

Yes, this question came up because the 9252 was not on the list.

My helis are still using 9202s on the cyclic (mCCPM). I was planning on upgrading the servos before I installed the new receiver but maybe I should try the new receiver in one of them to see if non-digitals see the 2048. Experimentation good :)

Has anybody tried using the Revolution whip with the new receiver. Any adverse affects?

Jeff

[Shannon Davis]

I noticed a difference in watching the swash on my Tempest just by changing the rec. from the 149 to the 14 channel. I have 9252's on by helis. I have not flown the new radio yet but hope to this week.

[bob00]

Hi Jeff,

I've been flying with a revolution whip - no problems so far - solid range check too, a little better than my 10x / 955 that it replaced.

Regards,
- Rob

[jbiter]

Thanks Rob.

I thought it would probably be ok. I was wondering because one of my helis suddenly had a decreased range check when I switched to the 14mz. Since I don't normally do a range check prior to every flight, I'm not sure if this problem existed with my 9Z. The solution on this helicopter turned out to be antenna location and after moving it, the range returned to normal.

Jeff

[MadMan]

I think the faster the servo, the more you are going to feel the resolution difference - no? I'm testing these as they are what looks like the fastest non-tail Futaba digitals and I am putting them on ECCPM cyclic this week.

Futaba S9451

SPECS: Speed: .13 Sec/60 Degrees @4.8V - .10 Sec/60 Degrees @ 6V
Torque: 97 oz-in @ 4.8V - 121 oz-in @ 6V
(7.0 kg/cm @ 4.8V - 8.7 kg/cm @ 6V)
Weight: 2oz (56g)
Length: 1.6" (41mm)
Width: 0.8" (20mm)
Height: 1.5" (38mm)

[Chuckie]

Remember the signal that comes out of the receiver to the servos is really an analog signal, a square pulse about 50 times a second with a pulse width or duration of 0.0015 second. All servos work off the same basic pulse signal duration and update rate and that is why they all will work with the 14mz or other Futaba, JR, or other manufactures equipment. The 9251 being the one case where it is used solely with the 601 where the pulse signal from the control unit to servo is like 300 times per second.

The 1024 or 2048 thing is the number of steps and distance of each step the servo can move as you move the stick on the tx. With higher resolution the finer the servo arm will move between the steps and the more steps you will have. It’s hard to see the difference but when you’re flying you feel a difference, more precise control over the model with 2048.

Finally, Futaba clams the 14mz has a 40 percent increase in frame rate, which is the signal update rate from the tx to the rx. Futaba could not have made an improvement unless the signal in the older radios was designed inefficiently. I read this as, the older radios could not send different position signals at 50 times a second to all servos at the same time. So as you moved the sticks the rx is receiving or sending older position signals to the servos.

So all servos should work better with the higher resolution and frame rate of the G3 receiver because much of the improvement is between the tx and rx. For the Rx it’s able keep up with the changes from the tx and pass along signals at 50 times per second to the servos. The servos like 9252 can keep up with the speed of the changes as they are already fast servos.

What I speculate is the newer Futaba servos have been made to respond more accurately to the incoming signal and have improved control over the position of the servo arm than older servos. I’ve posted my observations on flying the 9255s in my Tempest 3D and even though I have only a few flights on them the servos definitely have more control around center than 9252s.

The reason Futaba recommends new servos is probably because the older servos were designed with a lower resolution in mind and not as precise and so new ones are needed to match the improvements in the 14mz.

Chuckie

[slammers]

As Chuckie said, the signal into the servo is an analogue pulse position signal. The 14MZ being 2048 resolution will create this pulse train in finer increments than previous receivers. However, the servo has to be able to distinguish this position information in order to get the benefits.

With 2048 steps the pulse output from the receiver can be moved in approximately .5 micro second increments. Older or Inexpensive servos would probably not be able to detect such small changes in this input pulse position. And if they can not then the added resolution of the 14 has absolutely no effect in control response.


Shawn

[X]

So which is the best servo for this radio, I am currently using 9252 on my Extreme.

Thanks,
x