VStabi Pioneer of Flybarless

For safe use of a model helicopter it is needed to have a reliable power source. It isn't needed to get a redundant power supply - but it is needed to get a strong power suplly which is up to the needed requirements (e.g. power consumption of the servos).

We have to take a view on the maximum current draw of our servos. Using standard servos it may be up to 8A, with a HV brushless servo we have measured up to 15A. Therse values must be multiplied with the number of swash servos used in the model to get any kind of a idea what might go on in your helicopter. We have measured 20A for standard and 35A for HV servos.

Unfortunately there are many standard BEC out ther which may not be strong enough to handle these current draw. A voltage drop (caused by the "bottleneck" BEC and high consumtion of the servos) below 3,7V causes (depending a bit on the Radio) some fatal behavious of the model up to a complete model loss and damage. If you have any undervoltage warnings in the VBar event log (pro needed) it is definitely forbidden to fly the model until they are solved.

Using the following method you will be able to check your power supply on the bench. Attention: A inapporpriate check can cause a damaged ESC / BEC - we will take the BEC to its limits here.

To test the power supply it is needed to use the pitch pump (setup, swash tab, expert) of the pro version. We set the value to 100 and start with fast pitch (collective) pump at the sticks (motor off, hold the heli down). After 1 minute check the event log. If there is one or more entries with undervoltage now - or the model has shown reception losses in another way - don't fly until you get it solved.

A common used method to solve the voltage drops is a additional battery. This will be used as buffer for the current peaks and could possibly safe the model due a BEC failure in flight. The battery capacity, current, hookup must match to the BEC and used RC electronics. Most used batteries are 4 or 5 cell NiMH which needs only low maintenance.

Another method will be using a capacitor with enough capacity (min. 16V 4700 uF). It is very small and leightweigt, easy to connect and needs no maintenance.

Please have a look at the following pages linked below. We measured a lot of power sources and want to share our experiences with our customers to fly their models safe. This analysis can be transferred to all model helicopters, indepandent form flybars or flybarless and which system may be in use. We have reproduceable measurements and diagrams here made under constant conditions.