Remote Control Information

Indoor Radio Control Equipment

Servos - Equipment suitable for indoor radio controlled aeroplanes is getting smaller and cheaper all the time. Mass produced micro servos have halved in weight and price over a couple of years, so that you can now get a sub-6g servo such as the Hitec HS-50 for under £20. These servos are fine for many indoor R/C planes, although if you want to get down to smaller and lighter planes you might need one of the Westechnik 2.5g servos.

Currently we build planes at about 18" to 22" span using just motor and elevator control. This is what we call a virtuous circle - one 2.5g servo costs about the same as two HS-50s, but saves 9g which could be as much as 20% of the weight of the finished plane. That means you can make the plane smaller, which in turn means you don't need so much power to fly, so you can use a cheap 6g motor and less cells saving more weight and money. A smaller plane can be constructed with less strengthening than a larger one so it's easier to make it light, so the overall result is a smaller, lighter and cheaper aeroplane. This is how we arrived at our current designs for indoor radio controlled planes (see the indoor r/c planes page)

Receivers - again, receivers have got smaller and lighter very quickly. We have used Ceto, Potensky and Multiplex receivers in our planes, these all weigh between 4.5g to 7g depending on whether you take the case off. Some points to note are that the Ceto and Multiplez receivers use the tiny JST connectors which match the Westechnik servos, while the Potensky uses standard Hitec style connectors to match Potensky/Hitec/Futaba etc servos. The Potensky is good therefore for park flyers where you are more likely to be using the larger, cheaper 9g servos that are now readily available. The Multiplex seems to be able to run on just three cells, but remember that your servos might need more volts, and that the voltage may drop when the motor is switched on if you're using less than six cells. There are some other receivers out there at about 3g to 4g but we haven't tried them - check carefully what frequency they operate on, some are fixed and some are not available on 35MHz (which is what we use in U.K. along with 27MHz)

Speed Controllers - also known as ESC's (electronic speed controller). The main points to note are how many cells are you going to use and what current will your motor draw? Many speed controllers have a battery eliminator cicuit (BEC) which produces power for the radio system. These often have a 'motor cut-off' feature which switches off the motor or reduces power to it before the battery runs down so that the radio system still functions. You need to check the specifications of your speed controller carefully. A speed controller with BEC and motor cut-off designed for use with 7 or 8 cells may not be very useful on just 5 cells as the motor cut off may occur almost immediately. This was not a problem on our early indoor r/c planes as we generally ahd to use 6 - 8 cells anyway. However, we are now building planes that only need 4 or 5 cells to fly, so choice of speed controller is more critical. We use speed controllers that don't have motor cut-off or BEC, such as the 1 Amp Ztron ESC (rated for 4 cells but we've used it on 5), although we still run all the radio from the flight battery. In practice, the aeroplane has landed due to lack of thrust before the radio runs out of juice, but remember that we are using just one Westechnik servo in this application, which draws less than two HS-50s.

Infra-red Control

We are currently experimenting with Ztron infra red control systems. We've flown a 12" Fokker Triplane (the Infra-Red Baron) and we are now looking at twin motor steering systems. Infra red control allows a lower component count but is generally designed for flying one model at a time, which is not really a problem for short flights. Sergio Zigras of Ztron has produced a combined receiver/twin motor controller which we will be testing with a view to making sub-18" multi engined scale models. However, Ztron also produces infra red receivers that will run standard servos, or magnetic actuators although there is less opportunity for weight saving here as the servo and cells required for it still make up a large proportion of the weight. Actuators give a centre off with left and right selectable control, or a pulsed proportional system. We found it difficult to make very small actuators for our requirements, although we will revisit this after our multi engined experiments.

Radio control for Park Flyers

For park flyers the choice of equipment is much easier. Any of the receivers mentioned should be o.k. They do have reduced range compared with normal 'outdoor' receivers, but the aim of a park flyer is to build something small and fly it close. If you build something big you shouldn't be flying it on the park, should you? For servos, either the Hitec HS-50, Potensky, or any of the numerous 9g servos should suffice depending on type of model. A speed controller with BEC and motor cut-off can be used as you'll probably be using 7 or 8 cells.

Summary

For suppliers, see our suppliers page.