I'd like to upgrade my radio to the Futaba 9CH but don't understand the servo packages. I can get either 3001's or 9001's. What's the difference in these servos? Futaba's spec sheet shows that these as similiar, but I may not be reading it right. I'm flying a Raptor 30 currently. Can I use these servos in a 60 sized machine?

I wouldn't recommend either servo for a 60 size heli. The 9001 is a much better servo than the 3001. I wouldn't use the 3001 in any heli. I had a set of 9001's in my caliber 30 and they did just fine. I changed them out and replaced them with 9202's when I had the extra cash. They are now in my Hawk Sport and working fine. 9202's are the minimum I would use in a 60 size heli. For reference, the 9001 is a coreless motor servo and the 3001 has a standard three pole motor.
Later,,,basmntdweller

IF you are in the market, some of the heli mail order places will put together a complete radio system with the RX and servos that you want so you aren't buying stuff you won't be using.
Tower hasn't been real happy to do this in the past.

Korzry here is a servo comparison chart for you to look at. it has servo specs for futaba, hitech, jr and airtronics.


http://www.richmondmfc.org/servo%20chart.htm

the 3001 has 41 oz of torque
the 9001 has 54 oz of torque
the 9202 has 69 oz of torque

if you have the money and are using pcm then go with the 9252 servos, they have 91 oz of torque.

It is better to buy better equipment now then to realize later that you have to upgrade your servos and you wasted the money buying the old servos.

Alan...

Those figures are outdated. The 9202 has around 92 oz.in. of torque at 4.8 volts, if I remember correctly. It has as much torque as the 9252, but at a slower speed. Check out Futabas updated specs, they should be on their site by now.

http://www.futaba-rc.com/servos/futm0029.html
Futaba site says updated, I have no idea if it was done recently though.

Those rating are at 6 volts. the 9202's have about 55 oz of torque and .24 speed.

Servos with coreless motors generally are smoother. I digital servos on all of my helicopters. They are smoother, more precise, and have better holding pwer, but after you pay all the money you find that it really wasn't worth it.

Dyehard: i jhave to disagree with you, you have an elevated torque rating, the 9202 has 55 oz not 92....... the 9252 has 80% more torque at 92 oz.. the 9252 will not run on 6.0 volts. it was designed for 4.8 only. the 9202 can run on 4.8 or 6.0 volts

these are the current ratings for these servos.


Alan...

Alan, you are at least a month out of date on your information. There has been the an awful debate going on for the last several months about the specs on the Futaba servos. It seems that most of the older Futaba servos, including the 9202, were rated quite a bit differently from the industry standard. Ann Marie Cross, head of the Futaba division of Great Planes, asked Futaba, because of all the confusion being caused by the different ratings, to rerate all the Futaba servoes, at both 6 and 4.8 volts, to be in line with how everyone else was rating their servoes. Send an e-mail to [email protected] with "updated servo data chart' in the body of your email for a copy of the new servo chart. The current torque rating of the 9202 is almost identical to the 9252, which isn't suprising, since until the digitals came out it was Futabas standard 60 size servo.
BTW, the 9252 will run quite well on 6 volts.

Dyehard : it's not me but Futaba/ Great planes that is out of date with the servo specs, You are right with the numbers on the 9202/9252 servo. I stand corrected!





Alan...

I understand where you are coming from. Great Planes is who started the whole debate when they posted a list of servo data that didn't agree with what was on the servo packages. It made for a lot of stink that is just now clearing out. Such a shame, considering the servos themselves are some of the best you can buy.

Comparing apples to apples.

I think that torque and speed specifications (if all use the same standards) are helpful, but not as much as we think. And they can lead us into a number of misconceptions.

As most control systems need the servo to move from their current position to another position in order to change the position of a flight control surface (in heli's that would be the swashplate or t/r pitch slider) then it is very important for it to have power available ASAP to do so. This is what makes the biggest difference between the standard analogue servo and a digital one.

The analogue servo may spec at 100 in. oz. of torque but it has to move about 15 degrees before it has developed that torque. On the other hand even a poor digital will develop full torque after only about 3 degrees of movement. To test this, take your servo, power it up and try to move it by hand, you will find that the standard analogue servo will move a bit before building up enoough current to stop your push. Then try it on a digital servo, now you will find that even a weaker one will hold fast because it was able to ramp up to full power as soon as it detected a force trying to change its desired position.

In other words the analogue will give a "mushier" control at center. If ones helicopter control system is not very precise (has a lot of slop in the various bellcranks and control arms), then "feeling" the difference will be a lot harder then if ones helicopter has a tight precise control system.

This is also why a slower (e.g. .22) digital servo will perform a lot better on any gyro then will a much faster analoque (.06). This is because when attempting to hold the tail on heading against outside forces, the gyro will give a multitude of small commands for movement from the servo, as the analoque takes time to ramp up, it in effect will be slower then will the digital. That is because the speed spec is the speed for 60 degrees of travel. So the analoque may have a higher top speed (0.06 compare to 0.22) over a distance (60 degrees) but the other will have a much faster acceleration speed. The digital will attain its top speed within 3 degrees while the analogue will do so in 15.

Like two cars with different acceleration and top speeds. One will win in the quarter mile (digital) but the other in a one mile run.

I hope tis helps more flyers understand the spec relationships and differences in types of servos better.

True, though for the most part the digitals are both quicker around center and faster for 60 degrees of travel. As long as they are reliable and you can afford the price, they are the way to go. So far the 9252 has shown very good reliability and I would recommend them over any analog servo to someone who has advances enough to appreciate the differance. For someone on a budget, but wishing a servo that will still work well in a 60 size heli,the 9202 is still a viable alternative.

There is basically no difference in the 3001 and the 9002 apart from the coreless motor which gives an increase in torque. There is still only one bearing and they still have a fair amount of flex in the output shaft.

I would recommend going for servos with two bearings, coreless motor and metal gears on a 60 size machine... Especially on the pitch!

Dyehard,

Yes, the Futaba 9202 (coreless and double BB supported) do very well on 60 size helicopters, probably the "best buy" in this application.

AJ_UK

Metal gears? Be careful here. IMHO. except for absolute precision (e.g. a Hi-Zoot FAI machine, the metal gears are overkill - they wear faster then the standard Futaba nylon units. Consequently they need regular replacement to maintain the precision for which one paid the extra bucks.)

In some OTHER brands, I have even found the metal gears so badly machined as to fit so tightly that the advertised speed and torque figures where way out to lunch. In fact though the advertised speed was .11 the lowly standard Futaba S-148 (rated at .22) was a lot faster!!!

Needless to say, their current draw was herrendous, even more then any digital I have tested. Surely a crash just waiting to happen.