Taurus FAQ

  • 49′ 1½ wingspan
  • Glide ratio 41:1
  • Rotax 503 retractable engine and propeller
  • Unique side-by-side seating – perfect for training
  • Retractable undercarriage
  • 78 knot cruise under power
  • 3.1 gph at 78 knots cruise
  • Perfect for thermaling or slope soaring
  • Comfortable training or pure sports aircraft
  • Electric engine option – Taurus Electro G2

I wish to know more about the batteries used in Taurus Electro G2
Battery type is a special-made LiPoly battery, 10 Ah capacity per cell, 25 C discharge rate. The system includes 4 boxes where the batteries are located, the BMS also. The standard battery configuration is 128 cells, optional are 192 cells. They fit in the same 4 boxes in both cases.

The basic option gives you total capacity of 4.75 kWh, from which it is sensible not to use more than 80% due to battery cell life. Effectively you end up with 3.8 kWh of useful energy. This version fully meets European microlight standards regarding the empty weight! The battery pack weighs 10.5 kg per box, there are 4 boxes, totalling at 42 kg.

The optional pack adds capacity to reach 7.10 kWh total, again by taking 80% »sensible discharge level« you are effectively at 5.7 kWh of useful energy. This battery pack weighs 13.9 kg per box, there are also 4 boxes on board, totalling at 55.6 kg.

What is the endurance of the Taurus Electro G2 in real life?
In terms of endurance the following margins apply for the basic battery pack:
20 kW power output: 11 min 30 sec
30 kW power output: 7 min 40 sec
40 kW power output: 5 min 40 sec (theoretical, expected is 1 min on 40 kW, then reduced power)

The data may change because of ambient temperature. 80% sensible discharge level is taken into account.

In terms of endurance the following margins apply for the optional battery pack:
20 kW power output: 17 min 10 sec
30 kW power output: 11 min 20 sec
40 kW power output: 8 min 35 sec (theoretical, expected is 1 min on 40 kW, then reduce power)

The data may change because of ambient temperature. 80% sensible discharge level is taken into account. Please note that in horizontal flight only 7 kW is needed, so theoretical endurance reaches 1 hour.

What are the variables influencing the top-of-climb capability?
There are a lot of factors for this, from cockpit load, runway condition (how much energy you burn for the taxi&take-off), ambient temperature, thermal properties of different components, controller parameters, etc. Ambient temperature is the most important factor of all.

What maintenence is required for the powertrain?
The maintenance is virtually care-free!
Battery system takes care of itself but needs to be recharged to full charge at least once every 90 days to keep them »healthy«.
Controller maintenence: nothing, just clean the cooling duct.
Motor maintenence: check main bearing for axial free play and tighten main bearing every 10 hours of motor operation.

Is it mandatory to wait a long time until engine is hot before start?
Absolutely not. The colder – the better for the engine. It will not be recommended to apply full power however if the batteries are below 5 deg. Celsius.

How does the Propeller stop and the engine retract? Is it all fully automatic?
Yes. Fully automatic systems include the brake, which is all electric, and positioning via a magnetic 16-bit hall-sonde encoder. When the propeller is correctly positioned, it can retract. The stopping, positioning and retraction of the propeller work flawlessly at the press of a single button.

Is engine and controller cooling adequate even in the summer time Australian conditions?
The cooling is proving to be sufficient. In any case, there is a protection logic built in which will slowly reduce the power on the system if it will be picking up temperature too fast (considers also temperature gradient, not just limit temperatures!)

Is it possible to retract the engine right after stopping it, or is it mandatory to wait while the batteries cool down?
Batteries essentially do not become over 50 deg.C hot. It’s not necessary to cool them down – you can retract immediately at any time, mid-flight or on the ground!

Is it possible to extract and restart the engine mid-flight?
Of course. As with the retraction, it is all automatic.

Is there a recommendation »don’t take-off when the remaining power is under a certain percent« ?
The system will not allow you to do that. If less than 3 minutes of battery endurance is indicated, it will not go to take-off power and it will produce a warning.

How long does it need to charge at 220V?
3.5 hours for the standard battery configuration, 5 hours for the optional configuration. This is when the batteries are completely empty! You can monitor all this via the ESYS-MAN instrument. Charging is also possible form the Pipistrel’s Solar Trailer.

Is charging with 380 is recommended?
No, the charger is a single-phase 220V or 110V.

Is there any built-in safety in case of too high temperature or controller dysfunctions ?
There is a multilayer logic in place. The controller takes care of itself. In case of too high temperature it will first reduce power (up to 5%) and then switch itself off in case of severe over-heating. BUT BEFORE THIS OCCURS THE FOLLOWING WILL HAPPEN:
We have an on-board computer now. It measures not only the temperatures of all components of the system (motor, controller, 4 temperature probes per battery box etc), but also a bunch of other parameters and has the limit temperatures as well as limit temperature gradients programmed inside. For example, if the motor is heating up more than a certain amount of degrees-per-minute, it will reduce power to track the maximum permitted temperature gradient (slope), in order not to reach the limit temperature at all. The same goes for the controller, as well as for the batteries. Manual override is possible, of course. There are warnings which display on the screen, too.

Will parachute remain usable in case of battery overheat / fire ?
Thanks to the super-precise Battery Management System, which was specially developed by Pipistrel just for Taurus Electro G2, battery issues are extremely unlikely. Furthermore, the batteries are placed in self-containted metal boxes in the fuselage. In event of an overheat/fire, the parachute remains fully functional.

How is throttle control executed?
The system uses throttle-by-wire concept. The throttle input is received at the ESYS-MAN, filtered with protection logic and the reference for the RPM is then sent over to the motor controller via CAN bus. It is all very elaborate, not via a simple potentiometer as it is common with other aircraft.