On Friday, February 23, 2018 at 2:51:44 PM UTC+3, Stéphane Vander Veken wrote:
Why low passes? Well, to have fun, of course, but also because, according to some, going into ground effect some distance before the arrival line is the most efficient way to finish a competition flight.

However, according to most "mathematical minds", the energy loss incurred by having to accelerate to VNe and keep the speed at VNe until going into ground effect, can never be compensated by that ground effect. Certainly not if you still have enough energy when crossing the arrival line to pull up and do a 360 before landing. That energy is lost for the flight.

The most efficient is to climb *just* enough in the last thermal to cruise at MC=finalClimbRate and arrive at the finish line with zero altitude and land through it.

However if you misjudge that and end up short then it's a very bad day, so everyone puts an extra 500 ft or 1000 ft in the bank before starting the final glide.

Having done that (and wasted anything from one to five minutes more than you really needed to climbing), you can get a minute or more back by speeding up 20 or 30 km before the finish to again plan to arrive at the finish at zero altitude .. but with a much higher speed.