WAMASC Technical Information
2.4GHz Radio Issues
Many people do not have fail safe set up properly, let alone understand its purpose. The throttle should always go to idle with the loss of radio contact and control surfaces should centralise.
This has several benefits. It is an audible warning to you that the model has either an engine problem OR has gone into fail safe. It reduces airspeed, thus reduces crash damage and risk to the public. An aircraft that is slower has more time for recovery of radio contact before it meets the ground. A trainer with dihedral may well enter a gentle glide to the ground during fail safe.
With the model on the ground and the engine not running, set it up so that if the Tx goes off air (e.g., is switched off), then controls should centralise and the throttle goes OFF. Then check it with the aircraft suitably restrained and the engine running.
If running 2.4GHz equipment, be very aware that covering and construction materials of the model can have a significant effect on both range and directionality. If in doubt, mount the antennae on the outside of the model using Velcro or double sided tape, and protect it inside a small radome which could be standard Mylar or Teflon type covering or canopy material. Some plastics have a large absorption at microwave frequencies so not all plastics are suitable. It is critical that antennas be mounted for good radio visibility to the ground.
When doing a range test, walk around the aircraft in a 360° circle, alternatively have someone rotate the aircraft relative to you so that you may check for dead zones.
Setting up the fail safe with AR7000 receiver:
This procedure is not documented in the manual.
After initial binding & servo setup, perform another bind to allow failsafe to acquire correct neutral control surface positions. With TX off, insert bind key to RX charge receptacle, switch RX switch on and verify RX is in bind mode indicated by rapid flashing on RX & satellite RX. At this point remove bind key, RX will remain in bind mode. Select desired stick positions on TX and switch on whilst holding Bind / Range test button. Wait till flashing lights on RX & satellite RX go solid. Switch RX off & switch TX off, then switch TX on and RX on. Test for correct operation by entering extreme control commands & switching TX off, observing that servos reset to the desired failsafe position and throttle returns to idle.
Battery Information:
Generally speaking, 2.4Ghz radios are more demanding of battery packs and less tolerant to high resistance and low capacity than, say, older 36MHz sets.
Many aircraft fitted with Spectrum radio have “gone off the air” and crashed at around the 15 -20 minute mark from initial switch-on and the fault has been isolated to inadequate battery packs.
It seems many Spektrum sets have been supplied with an unbranded, 4.8V NiCd battery pack of unknown quality and approximately 600 – 800mAh capacity. This is quite inadequate and these battery packs should be discarded as soon as possible. Feel free to ask the retailer what happened to the genuine battery packs the radio should have been supplied with.
Fit at a minimum, a quality, brand name battery pack (such as Sanyo) of 4.8 volts and 1200mAh or larger capacity. Better still, use a 5 cell pack of 6.0V and 1200mAh or more capacity. Do not use a higher voltage than 6.0V as damage to servos may result.
Please be aware that if using other than a 4.8V battery pack then you will need to purchase a suitable charger for it as the standard supplied charger is only suitable for 4.8V packs.
Tony Belts
AUS 42905
7 March 2010
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