I have another couple questions. In the interest of learning only, I'm not buying anything atm.

1. When picking out a servo like the HS-55 (which I'm getting for my SlowStick), I know that weight and torque are a factor, but how do you really know which servo is best? For example, how would I know if it were possible to use say, an HS-81 with my Slow Stick. Would that even work? (I'm not looking to do that, I'm just asking theoretically). I know the HS-81 is a little heavier and a little bigger, more powerful, but is it TOO big and TOO heavy for the SlowStick? How would I figure that out in general terms for any plane?

2. When choosing a receiver, what is the difference between DUAL conversion and SINGLE conversion? I'm getting the HFS-04MG with my Slow Stick, which is single conversion, but there's also the Hitec Micro 555 which is dual conversion. What's the difference? And how do you know whether you need to choose positive or negative shift? I think I've been told to choose Negative shift for my Hitec Laser 6 transmitter, but why am I doing that?

Thanks in advance guys...

Cheers,
D.

1. From everything I've read, the Slow Stick can carry more then it's share of weight. You can actually use full size servos with it. In regards to say a HS 81, yes it will work, do you need it, it's more likely whether or not your going to move up to a stronger motor. Then the torque makes a difference, there will be a greater force against the elevator and rudder as you increase speed, and your servo won't slip. Speed always makes a difference in how fast the servo reacts.

2. As I understand it, Dual Conversion reads the signal twice, in order to sort out bad signals, while single conversion just takes the information received. In regards to postive or negative shift, Futaba and Hitec use negative shift while JR and Airtronics(Ibelieve) use postive shift. This has something to do with which side of the high or low frequency that the information is sent out on and read by the receiver.

Good luck.

Thanks very much, makes sense. I suppose what I'm really wondering is, if I buy one of the kits from Mountain Models or any of the smaller ARF kits, would I be safe with HS-55 or should I get HS-81? At what point (how large of a plane/motor) would I need to consider a larger servo than the HS-55 or HS-81?

I would have to say it really depends on what the manufacturer recommends, then what people with experience use and recommend. These forums are always great because their are people out there with the planes and have the first hand knowledge of what's needed. Good luck.

Thanks Randy, I wondered if there was a 'rule-of-thumb' for park flyer servos, but I suppose one can't be so lucky! I appreciate it, anyhow.

I wouldn't say it's a "Rule of Thumb" but in regards to servos in most applications, "It's the fastest, strongest and the best you can afford." Also it has to fit within the size parameters of each given instance. There are times that it can be an overkill, but that will be noticeable. Good luck.

Add to that, "and what looks about right."

There are really only about 5 classes of servos in common use:
Pico (HS-50)
Naro (HS-55, HS-60)
Micro (HS-81, HS-85)
Mini (HS-225)
Standard (HS-425)

...and there's quite a bit of crossover where at least two different classes of servos would work equally well. It's really hard to go wrong.