there isn’t in this one. We did have a generator in an earlier plane (back in 2012), but we removed it as it really wasn’t helping and was causing some mechanical problems.
For the plane in the above video we were aiming for a bit over 1hr flight and it only needed quite small avionics battery. To change the VTOL motor batteries would have been hard as they are high capacity (8.8Ah of 6S) so it would have taken a lot out of the petrol engine to charge them.