Hero emulation

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. You can just have fun with it, if it doesn't scare you to death - or kills you.

Some years ago (2003-2004, IIRC), the British Juniors published a series of "smoking vid" DVD's that were sold as a fundraising source for them and showed some of the most crazy low passes you can imagine. I even seem to remember a low pass by an Astir CS where the belly of the glider actually touched the ground at full speed, going straight at the camera. Sure, it was fun....

But then, at the Junior World Gliding Championships at Husbands Bosworth, Leics, in August 2005, Neil Lawson, a well known glider photographer, was killed by the low passing glider he was photographing. No more "smoking vids" after that event. And the championship rules where amended to actively discourage low pass arrivals.

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.

At 12:24 23 February 2018, Bruce Hoult wrote:

The most efficient is to climb *just* enough in the last thermal to
cruise
=
at MC=3DfinalClimbRate 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
fi=
nal glide.

Having done that (and wasted anything from one to five minutes
more than
yo=
u 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.


Thank you Bruce for sparing me the need to spell it out for those
who have not done much competition flying. We "fudge in" extra
altitude for unexpected sink along the final glide. I was once at
120 Kts, full of water, 5 miles from the finish, at 2,000' AGL (at
Hobbs in the early 1980's), and even passed up a 10 Kt dust devil
along the way, only to run into extreme sink and headwind over
irrigated fields in the last couple of miles so that I was just barely
able to make a direct rolling finish. Other times, one runs into
unexpected lift along final glide and winds up with a lot of excess
energy, some of which can be converted to speed points by doing a
flying finish. Now, if all of the minimum finish altitudes are jacked
up, and direct rolling finishes are not allowed, that is again another
matter, but contrary to some people's opinions, there has been a
place in competition soaring for low flying finishes.

RO