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Radio - Servo - Gyro - Gov - Batt > New Futaba Servo???????
 
 
seattle_helo
Key Veteran
Location: Seattle, WA USA

Are they manufactured in Japan by any chance?
08-29-2008 01:35 AM
HOMEPAGE  
 
 
heli_headcase
Key Veteran
Location: Hovering around Atlanta

The BLS252 has "Made in Taiwan" molded into the bottom case cover.


HHC

So many heli's - too little time...
08-29-2008 03:14 AM
 
 
seattle_helo
Key Veteran
Location: Seattle, WA USA

Copy that. Thank you.
08-29-2008 04:47 AM
HOMEPAGE  
 
 
hyflyr
Senior Heliman
Location: Baton Rouge, LA

If the Japanese price is the same I would bet the leads are the only difference. How could they not charge more in Japan if they had to make a special run for the lower deadband. The 451's are for the car guys and the 252's are for air. The car guys are just as serious about their controls as us heli freaks. They need 2uS deadband every bit as much as we do. At the current exchange rate the are both at $97 a piece in Japan. We are getting Jacked over here is all.
08-29-2008 05:42 AM
 
 
heli_headcase
Key Veteran
Location: Hovering around Atlanta

Huh?

Quote 
They need 2uS deadband every bit as much as we do.

I'd think the cars would benefit from 1uS DB. But I'm also thinking as long as there are constant large control inputs the "electrical freeplay" isn't very noticeable as, say, precisely hovering a heli - a task requiring the smallest and most subtle motions. And since car steering is a single function operation, using a large swing of the servo arm, control resolution is maintained. Heli's using electronic cyclic-pitch mixing are using roughly 50% output arm swing per flight function, and this dictates the tighter (1uS) DB for best available control accuracy per function.

I'm betting Futaba's latest digital heli-specific servos are even better than 1uS, thus matching the 2048 step resolution available from the 14 and 12MZ systems. I can't measure real deadband numbers less than 1uS but playing with the minimum trim step in the 14MZ has shown that something good is happening in there, I just can't assign a number to it


HHC

So many heli's - too little time...
08-29-2008 06:02 AM
 
 
abrajim
Senior Heliman
Location: bogota colombia

heli_headcase have you try the deadband of the bls451?

sorry for my english
09-11-2008 06:22 PM
 
 
heli_headcase
Key Veteran
Location: Hovering around Atlanta

Sure did...

Quote 
have you try the deadband of the bls451

Yes, and it fits the pattern of 2uS DB for a servo not specifically designed for heli use. It's a fantastic servo in general and if your "thing" is lots of largish cyclic movement, you'll never notice the 'electronic play' that it has.


HHC

So many heli's - too little time...
09-12-2008 02:11 AM
 
 
Rymps
Veteran
Location: Indianapolis and Windsor CO

heli_headcase
Can you tell the dead band when flying? I don't think i could or many others. How can you tell? I would like to know more. Thanks
09-12-2008 03:09 AM
 
 
heli_headcase
Key Veteran
Location: Hovering around Atlanta

Can I tell?...

Yes, if a specific comparison is made between two distinctly different servos on the same heli setup. The key here is having the best possible resolution when it helps, IE: Pattern contest work and scale flight where you want every last little stick input 'heard' by the heli. And again, if you are flying the currently popular eCCPM mechanics as opposed to mechanical mixing, the servo precision must double to maintain the same degree of flight accuracy.

Some may notice the difference, some may not, but there's nothing wrong with using the best stuff possible if available. Your results may vary...


HHC

So many heli's - too little time...
09-12-2008 03:21 AM
 
 
ron g
Heliman
Location: Baton Rouge, LA

"Fits the pattern" does this mean it is 2uS or you think it is? How are you measuring the deadband? I would be curious to see the difference in a BLS451 and the BLS253. It may just be the difference in the gearing and or motors on a 252 vs 451. Just curious. Does not really make much sense that there would be such a significant difference.

you are a gentleman and a scholar, and your looks are only exceeded by mine.
09-12-2008 04:08 AM
HOMEPAGE  
 
 
abrajim
Senior Heliman
Location: bogota colombia

 i am wondering what deadband of the 8717 is?

sorry for my english
09-12-2008 04:08 AM
 
 
heli_headcase
Key Veteran
Location: Hovering around Atlanta

Quote 
does this mean it is 2uS or you think it is?

I know 100% the S9451 and BLS451 are both 2uS DB. The "pattern" is the numbering system as I described earlier in the thread.

Quote 
How are you measuring the deadband?

With the DB measurement function of my Hitec HFP-10 servo programmer. It's a universal tester when doing many of its operations, only programming Hitec servos uses the minor functions. A pricy box but very handy to have around. I take it on the road when attending events.

Quote 
It may just be the difference in the gearing and or motors on a 252 vs 451.

Gearing and motors only has an effect on speed and torque. The DB is a function of the 'amplifier' circuit and its ability to generate an error pulse that drives the motor when the commanded position and feedback pot position don't agree.

Quote 
i am wondering what deadband of the 8717 is?

I'm willing to bet it's 1uS or better. I don't have the wide selection of JR digital servos that I have of Futaba but all JR 'large' digitals I've checked are 1uS so far.


HHC

So many heli's - too little time...
09-12-2008 04:47 AM
 
 
Four Stroker
Veteran
Location: Atlanta

I put three BLS451 servos in my Kalt Mercury 50 with a Sanyo RC 2400 4.8 volt pack. I finally got around to test flying it yesterday. These servos are definitely smoother than the 9250's that I was using which was obvious in hovering maneuvers. I did not notice the deadband being a problem. I was overall very pleased. These servos did not draw any more current in my usual flying than the 9250's. Of course, the 9250's are some of the original "jumpy" digital servos. I had to use an extension on all three CCPM servos. The lugs are in a different place and I had to make 2 mm spacers to get the servos in the sideframes.
09-19-2008 10:35 PM
 
 
ron g
Heliman
Location: Baton Rouge, LA

I am still not convinced that because the BLS451 has a 4 in the part number that it is has a 2uS deadband. How does the BLS451 directly compare to the BLS253? I find it hard to believe they would use different control circuitry for essentially the same exact servo. It makes no sense from a manufacturing perspective. The manufacturer is not charging anymore for either so why would they change the control board?

you are a gentleman and a scholar, and your looks are only exceeded by mine.
09-19-2008 11:35 PM
HOMEPAGE  
 
 
Four Stroker
Veteran
Location: Atlanta

Servo parameters have always been set by a few external (to the chip) components.
09-20-2008 01:20 AM
 
 
heli_headcase
Key Veteran
Location: Hovering around Atlanta

Quote 
I am still not convinced that because the BLS451 has a 4 in the part number that it is has a 2uS deadband.

What would it take to convince you? It's not my job to do so, I just provided the spec as measured and there's a pattern to the part numbers, accept it or not.

Quote 
Servo parameters have always been set by a few external (to the chip) components.

But digital (uP controlled) servos are all programmed for performance type. External components (caps and resistors) only take on the jobs of signal buffering/shaping, bypass and noise reduction. Oh, motor drivers too... Just look at the Multiplex and Hitec as well as Hyperion and other digital servos on the market. All are programmable by the user via a programming device to set parameters such as DB, speed, end points, direction and fail-safe.


HHC

So many heli's - too little time...
09-20-2008 08:59 AM
 
 
Four Stroker
Veteran
Location: Atlanta

You are correct Steve. Digital servo amplifiers could be programmed for different mechanics or applications. I suspect that the Futaba digital servos are programmed somewhere in production or testing since a new set are perfectly matched and the pots aren't that good. Futaba USA denies the existence of a programmer.

My point was that yes indeed, different servos have different control loop parameters.

P.S. The Hi Products AD-46 blades have reappeared as AD-50.
09-20-2008 04:14 PM
 
 
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