I am frequently asked what kind of servos should be used for a specific airplane, or what kind of battery, etc. Most times the question takes the form of “Is XYZ good enough for this plane that I am building?”
The short answer is yes. If you are buying a radio, a servo, a battery or an engine in today’s market, for use in a normal airplane, it’s adequate for your purposes.
When the modern radio control system was first available in the late 1960s (digital proportional control of each function on the airplane) the airborne components were huge and heavy. The servos produced a moderate but adequate amount of torque. Response speeds were also moderate but adequate. Engines in those days were not phenomenally powerful. With care, the average guy could build an airplane which, although a bit heavy by today’s standards, could provide robust performance, execute most maneuvers, and return safely to the ground. Here’s a good photo from RC Modeler magazine in 1968, showing huge radio components packed into a 42 inch plane called the Wildfire. Combine that with fabric and dope, and this model probably weighs a ton. This is actually where most of the fun came from back in those days. It was a challenge to build an airplane light enough to fly with available power, and strong enough to carry the weight of the radio. It was possible, but it was a bit of a challenge.
Fast forward half a century and think about the question again, about some servo or battery being good enough for your airplane. Even with stock gear you have more power, less weight, stronger servos, and more battery capacity than the guys from the 1960s and 70s ever dreamed of. If you buy special components your specs are even more impressive.
In the 80s a lot of guys started using quarter scale servos in their giant aircraft, which were a new thing at the time. For pattern planes and super high performance aircraft the manufacturers offered fancy servos with quicker response times and more torque than a standard servo. Also metal gears became available. Some folks started using 5 cell receiver batteries producing 6 volts, for even more torque and faster response. The disadvantage of higher voltage of course is faster current drain and reduced battery duration. But the question is about components being good enough, and the answer is that a lot of equipment came on the market to provide higher performance than standard batteries and servos.
I’m just a guy who builds toy airplanes and likes to see them fly. I don’t build giant scale, I don’t compete in pattern aerobatics contests, I don’t fly jet models, and I don’t build feather weight micro models. The wingspan of my planes tends to range from about 32 inches to 8 feet. So I just use standard servos of the type supplied with a new radio. In other words, plastic gears, analog, about 8 or 9 bucks. If I ever need more performance I’ll use two on one channel, such as one per elevator half or one per aileron. In the 1990s I used to build 049 powered airplanes with two standard servos and a full size four cell double A receiver battery, because that’s what these planes were designed for and it worked great. Almost all planes were designed for that kind of equipment, because that’s what was available. Nowadays I tend to use triple A batteries and micro servos in 049 size, and mini servos in 10 to 15 size, but for everything else I use standard batteries (four nickel cells) and standard servos. I don’t worry about modern standard RC gear handling the job because I know it will.
Please do not assume, as many have, that I am telling you to use standard servos, 20 year old transmitters, nickel batteries, etc, because that’s what I do. That’s not what I’m saying at all. I am only trying to answer the question “Is this servo, battery, radio or engine good enough?” The reason I’m telling you how I do it is because it answers the question. I’m a cheapskate, I use cheap standard gear and it always works, thus providing a bench mark for beginners. If you want to use metal geared servos, cutting edge battery technology, digital servos (which draw current like nobody’s business), computer radios, high torque servos, etc, go for it. Just remember that you will have to match one fancy component to another, such as a high capacity battery to feed your hungry digital servos. Or you’ll have to look up the torque specs on your super miniature servos. It’s a hobby, so have fun. But that’s not exactly what I’m talking about. If you’re building a normal, average airplane, and you’re wondering if your gear is good enough, don’t worry. For a standard plane, standard equipment is good enough. Just look at the photos in the old magazines from the 60s and 70s if you don’t believe me.