Electric R/C Flight
By Heather Mardon
Unique Electric Aircraft Categories
There are several types of aircraft that are unique to electric power, they are as follows:
A rapidly growing category due to the availability of micro radio gear and small motors. Ideally suited to indoor flight electrics are clean and quiet. Most weigh under 400g and should ideally have wing loadings of less than 6oz/sqft. The low wing loading means lower speed flight The need for lower speed will become apparent the first time you ever try flying a plane indoors, the walls and ceiling can close in at a very rapid rate. Distance judgement is very important with indoor flying.
The largest motor commonly used in indoor would be the speed 280. Much above this results in a plane too heavy and fast for indoor use. There are a few exceptions to this, I have seem some highly aerobatic planes flown indoors on high power brushless setups, but there flying style is closer to that of a helicopter than a plane!
A very common indoor motor/gearbox combo is the GWS IPS system. This can power models of up to about 250g all up weight.
A hotliner is a sleek glider like design with a very high power motor (usually a brushless). They can be used for general fun flying or competition (F5B & F5F class).
These gliders usually have fairly high wing loadings due to there batteries and motor but can still thermal, just faster!. Most hotliners range from about 1.4m wingspan up to about 2.1m. In most cases they are all moulded glass/carbon affairs but a few entry level models will have sheeted foam wings instead.
At the fun level their motors will draw anywhere from 40A up to about 80A. Competition grade setups can draw up to 100 amps!!! You can see why they call them flying welders. At this sort of current draw the batteries can only handle a few seconds motor run at a time without melting down.
The concept of hotliners is to use the motor to rapidly gain hight and speed, then power off. The blades of the prop will fold flush to the fuselage for less drag. This stored energy of height and speed is then expended in fast dives and aerobatics. These planes have excellent energy retention so you may get several minutes of fun before lighting the fire again.
F5B competition is a multi task event. The first stage is to complete as many legs of the 150m course as possible in 200 seconds using up to 10 bursts of motor power. After this there is a 10minute duration task followed by a spot landing.
(FYI the 2002 record number of legs in 200s was 43, that gives an average speed of well over 116kmph)
The difference between F5B & F5F is just the number of cells allowed in the plane and its aerodynamic restrictions. F5F is 10cells, F5B is up to 27 cells.
By there name parkflyers are planes that can be flown in a park! There is no hard and fast definition of what constitutes a parkflyer but a bit of common sense needs to prevail here. I would suggest that a suitable model would have a weight of under 500 grams and a wing loading of less than 10oz/sqft as a reasonable rule of thumb. Electrics are park friendly due to there low noise and ease of use, no need to take starting equipment along with you, just pockets full of charged battery packs.
The number one concern when flying a model in a park is safety. I would safely fly my own Dragon fly in the park, but not a sport 400, even though they weigh about the same. Why? One has a top speed of about 20km/hr , the other about 60km/hr. This means the sport 400 covers a lot more ground and has far more stored potential energy. Just use common sense and ask yourself the following question "If this thing hits me in the head at full throttle, am I going to need a trip to the emergency ward!" (Or at least some first aid) If the answer is yes then perhaps it is better flown at the club field.
Until next time
Keep your Watts Up