Electric Power Information

We have used many different electric motors in our aeroplanes. Rather than give you lots of detailed technical information, here are the set ups that we have found most succesful for the sort of aeroplanes we fly. The smaller motors are towards the top of the page, with bigger stuff lower down, including suitable combinations for parkflyers. Details of where to get these items can be found on our suppliers page. We are not particularly interested in duration. Indoors, we want to achieve realistic and prototypical performance which is usually achieved by carrying the lightest possible battery pack not by carrying lots of capacity for a long flight. Remember, if your electric plane flies about for 10 minutes indoors you are likely to piss off all the other people who also want a go.

Simon's Small Stuff - Capacitor Powered Free Flight

If you want to make great little electric planes about 10" - 14" span why not try capacitor power? The capacitor is a bit like a high voltage low capacity cell. A 3.3 Farad capacitor weighs just a bit less than a 50mA/h nicad cell (about 3.5g) but it has the ability to give out about 3.5 volts initially as opposed to the nicad cell's 1.2 volts or so. This means that one capacitor has enough urge to get a small motor to fly one of our very lightweight 2mm foam planes such as the Jiglet or the Flitzer. Total weight will be about 10 - 12g. The duration will be from 30 seconds to a minute depending on the plane, but you can recharge in about 20 seconds from three nicad cells in series (3.6v). My capacitor powered planes are still flying after about two years of this abuse. The set up I use is the CMS-1 motor(5g), with a 3.3F Gold Cap capacitor, direct drive to a Union 80mm plastic prop cut down to about 70mm and scraped thinner, or make your own prop from yoghurt pot plastic. If you want to go slightly bigger, say 18", you can use the 4.7F capacitor and get a slightly longer flight.

Battery Power for Free Flight

The next step up from capacitor power would be a KP00 motor (5g) and two 50mA/h nicad cells(about 4g each). The motor can be used direct drive as above with the Union 80mm propeller, or it can be supplied with a gearbox and variable pitch propeller allowing fine tuning of the thrust. Three and four blade props are available which make it good for scale aircraft. I have used this set up on a 2mm foam 18" Me.109 and it flies very well.

The main problem you are likely to come across is that the plane will fly for a long time so you have to trim it very carefully to avoid hitting the walls or ceiling, which is why we started using micro radio control systems. Start off with a very short charge until you have it trimmed out. Electric power is also great for multi engined planes where there might not be room for rubber motors in the nacelles, and you can add another cell if you need a bit more power, but these tiny motors can be damaged if you draw too much current from them for too long, so try to keep it below one amp. It is also possible now to buy timer circuits which allow you to set different periods for full power, cruise and cut off allowing a burst of power to get off the ground to a safe height without carrying on into the rafters!

The sort of planes that will fly on a KP00 motor can also be flown outdoors on very calm days. For larger outdoor F/F planes use the KP01 motor and 2 x 50mA/h cells which is capable of flying heavier planes more able to cope with a bit of breeze - I have successfully flown a 26" span Piper Cub on this set up, but be careful not to charge it up too much or you might lose it like me!

Useful Motors for Indoor R/C planes

There are two set ups that we have found particularly good for indoor r/c planes. Currently we use the Westechnik Micro 4.5-0.6 motor which ways about 6g and costs only about £5. We gear this motor about 3 or 4 to 1 on 5 x 50mA/h nicad cells and the KP01 plastic propeller scraped with a knife to make it thinner. This set up is ideal for indoor r/c planes up to about 22" span and about 60g weight which are much more 'hall friendly' than the bigger types. See the Gladiator, Moustique, DH2 and more on the indoor r/c page for examples of planes using this set up. By using a cheap motor the money saved can be spent on a single 2.5g servo for rudder control (you don't really need elevator on this size of aeroplane). You can use up to seven cells on this motor but it may shorten its life. We hope to be able to use less cells in future allowing smaller aeroplanes by using step up chips to run the radio system at five volts from a three cell pack. At this point we may start using the KP00 motor for indoor R/C. One of these chips has been trialled successfully in my Twin Thing for some time now, and we are now experimenting with more powerful versions to run the servos.

Our earlier indoor r/c planes were a bit bigger and needed more power. For these we used the Westechnik DC 5-2.4 motor geared about 10:1 with one of their carbon props on 6 or 7 x 50mA/h cells. The motor weighs about 10g. Using small ballraces and 2mm carbon rod shafts a lightweight gearbox can be made. These motors are quite expensive but very efficient allowing the use of the 50mA/h cells which saves a lot of weight on the bigger models.

Park Flyer Motors

The best value motor we have found so far for small park flyers is the Potensky POT-2A which costs about £15 including gearbox and propeller. We have used this in the 24" Corsair, and bigger powered gliders (like the Caprice) - see the park flyer page for details. We usually run this on 7 x 120mA/h nicad cells, or you can use 7 or 8 x 150mA/h NiMh cells. Current draw is about 1.2A. This motor is similar to the Ceto TP03. For bigger park flyers you may need something like a Graupner Speed 280, which is typical of the motors supplied with a lot of 'off the shelf' park fly models, however we have little experience of this as we don't usually build planes that big (we only have small parks!)

Summary

For suppliers, see our suppliers page.