I have a real simple question. I bought a new plane and engine. A world Models Fun-Fly 40 and a Aviastar 53. My problem is my servoes. All I had in my shop were old S-148 servoes. I found one I think is bad because on the ailerons it's slower than the one on the other wing and does not have the same strength. Any -how I think that they are to weak for the plane. I don't fly 3-D all the time but I do sometimes. Which servoes would you recommend. I have tried off-brand and have not had been satisfied. I want to stay with Futaba. I use a 6EX Transmitter and 4.8 volt battery. Cost is an issue as I am limited on my budget. Thank-you

I am notFutabatec support but you may find some help here -> http://servocity.com/html/futaba_servos.html When I find myself faced with the same questions you pose, I check out the stats, performance and price here for what seems like a good fit for my next project.

As you look at the information, I always keep the Futaba 9252 in mind. At $75.00 with 92 in/oz of torque and speed of .14 sec/60deg they are my datum point. Add a bulletproof reputation and digital performance and they are what I personally compare all other servos to. Using the 9252 as a starting point you will find faster/slower, torquier/weaker, cheaper/more expensive servos but they will always look pretty good.

Hope this helps,


Bill

The S148 servos are not too weak for a .40-.50 size airplane unless you have extraordinarily-large control surfaces or the airplane will be flying extremely fast.  That size servo used to be routinely-used in .60-size Pattern aircraft.  Your difficulty stems from the fact that your servos are old and are most likely no longer working at their intended power and speeds.  If you replace them with equal or slightly-stronger servos, you'll do very nicely, indeed.

Here's where you can look over all the current-production Futaba servos:

http://www.futaba-rc.com/servos/index.html

Thanks Bax, I flew it again and have had no problems. I think that they had been sitting to long and had maybe gotten a little dirty or dusty inside. I looked into getting some newer ones and found the 3004 to be just a little stronger and  I can get them for about 15 a piece brand new.. Still gonna stick with Futaba. James