During the WRE with the Jonkers JS-1, I practiced several early
starts of the kind that would be necessary to meet the 1,000 mile goal I was
after. Of course these occurred in weak, relatively low morning thermals. To fly
1,000 miles or more over a 10 hour period or so requires more than 100 mph
average groundspeed, even early in the day when conditions are such that simply
staying up is the accomplishment. How does one doe that and also achieve high
cross country speeds?
On one of these mornings I did a direct comparison of two runs along the same
early morning street using typical flight techniques and Macready theory on the
first run, and the pitch-based dynamic maneuvering for energy harvesting, which
I have continually refined since 1997, on the second run. The lift was so light
that I could not sustain level flight in the first run but could run upwind for
a while with minor altitude loss and then had to stop and circle to get back up
to altitude. Similarly, when doing the dynamic maneuvering run I lost a little
bit of altitude along the same street but converted the extra energy into much
higher speeds against the wind (both runs were flown into the wind to remain
near the airport).
Here's the first cut of a video put together by Jonathan Dietch which compares
the two runs, generated from the flight log. The gains from the run shown in
this video, which is not optimized because the dynamic run was so much faster
that it included me crossing a sink street and contacting a lateral street, but
stopped there before those benefits. Even so, the dynamic run is 155% faster
with all things equal. The optimized comparison, that concludes along the same
street, was nearly 200% faster.
Soaring contests are often won by a few percentage points. This manifests the
parity in top designs and similarity of skills among top pilots and the flight
techniques they employ. However, such percentage gains are produced by
logarithmic gains in total energy and efficiency. For an example, for one pilot
to fly 5% faster than another, all things being equal, requires that he actually
fly more than 10% better overall since his speed is a function of the square of
the total energy for the flight. In the conservative case comparison shown in
the video above, a 155% increase in speed requires harvesting more than 240% of
the atmospheric energy than using traditional MacCready Speed-to-Fly theory and
course variation to follow the best energy lines. These things are evident to a
careful observer of Jonathan's video.
Jonathan is helping me refine the data so that I can share it at a lecture which
I have been invited to give at the World Gliding Championships by a good friend,
Loek Boermans, who is President of OSTIV- the scientific arm of the world
gliding community. I hope to return to Uvalde in a couple of weeks to do that.
