Sink rate is entirely dependent on span loading, span efficiency,
and drag. Wing area doesn't effect it, other than more area generally means a
lower aspect ratio, and therefore lower span efficiency. So more wing area
generally hurts the sink rate, contrary to the standard hang glider pilot train
of thought.
Look at the sailplanes, with 100 sq. ft. Of wing area, very high span loadings,
but also very high span efficiencies and low drag. Their sink rates are down at
60 fpm.
Not flying anymore, but still reading the Oz Report.
(editor's note: I will continue to look at how the VX compares
with the VR re sink rate.)
On Sunday, I set a new world record for speed around a 50 KM FAI triangle after
failing to break the record on Saturday (see below). The new record is 44.55 kmh.
My old record was 40.80 kmh. I did the same task as the day before but in
reverse order, going to a turnpoint nine and a half miles north of Quest Air and
just north of the Florida Turnpike, then eleven miles west to Center Hill and
back southeast 12 miles to Quest in one hour seven minutes and forty seconds. My
goal was to do the task in one hour. Maybe next time.
The forecast for today was especially good with very light winds and a high
cloud base. Still cloud base was only 4,700' at Quest and I left the 400 meter
cylinder around the Quest Air start point at 4,500'. That meant I had to come
back with 1,100' of altitude when I entered the finish cylinder.
There were plenty of cu's scattered around to the north so it was easy to stay
high and I made the first turnpoint in 18 minutes. I was trying for 20 minutes
per keg, so I was off to a good start. The next leg 11 miles west presented more
problems finding good lift. The cu's were forming and dissipating quickly and
now I was low, at 1,500' AGL four miles from the Center Hill turnpoint. I had
been keeping my eye on a big dark cloud at that location, but I found only 200
fpm underneath it and since I was low and had searched for a couple of miles
under the cloud finding only light lift, I stayed with this for three minutes.
The wind was out of the north at 8 mph and although it was away from the
turnpoint I decided to head further south in search of stronger lift under the
same cloud. I saw a Black Vulture turning low to my south, came over it and
hooked 800 fpm up to 5,500'. It was then a race to the turnpoint and back to the
same cloud.
I didn't find that lift when I came to the cloud, went to the next one, and then
the next one, newly forming, and finally at the fourth one four miles from goal.
I found good enough lift to get me up just high enough to make goal with enough
altitude to get the world record.
I see a number of places where I could have been faster. I think that it would
be quite possible to shave 7 minutes off the time required to do the task.
I spoke with Joe Gregor, who wrote the accident report on Terry's accident, at
Quest shortly after Terry's death. You can find Joe's report
here.
In my original article on the accident I wrote that, "A competitor augered
(literally) himself into the ground today, doing two three sixties very low." (I
didn't know who it was at the time). I was criticized by Terry's friends who
were with him at Quest Air at the time for this description as they apparently
couldn't believe Terry would do this. They were unhappy with me despite the fact
that I was just describing what I and others witnessed.
Well, if they still doubt the accuracy and validity of that original observation, I
suggest that they check out Joe's report.
The forecast was for winds at 5 to 10 mph out of the east southeast. On Friday
it was 21 mph at cloud base right out of the east. Dustin Martin dropped by on
his way to Brazil to tell us about the winds.
On Saturday I was waiting for a better triangle day, but the earlier winds died
down and with beautiful cu's everywhere the sky began calling. Then Paul Tjaden
mentioned how vulnerable he thought my 50 km FAI triangle world record looked at
40.8 kmh. I went back to my desk pulled up SeeYou put in a 50 KM FAI triangle
task and raced out to the launch line.
The lift was not so great at first but we finally found lift to get up to 4,880'
right over Quest with a sailplane, whose pilot was hanging around taking
pictures of us. I could see the flashes from the cockpit.
A 50 KM triangle is not much of a task. Paul was just recovered from his cold
and from our 150 KM attempt a few days earlier. The idea is to cover the
50 KM in an hour (say, that's 50 kmh). With this short a task you've got to come
back no lower than 2% of 50 KM below your start altitude (3290'). I'd set the
world speed records for the 25 KM and 50 KM FAI triangles in 2001 at Wallaby
Ranch, also in the middle of May, and hadn't thought about defending them since
then:
Once you set a record, you figure it is someone else's job to take it away from
you. But, 50 KM looked like a sweet distance for an afternoon of fun, so we were
game for a try.
The first leg was only twelve miles to Center Hill. Cu's every where. Five miles
out I found our first thermal. By tightening up in the better core I was able to
climb in the VR to cloud base in five and a half minutes at 420 fpm. Paul was
making wider circles, which he felt the VX liked more, and climbed to cloud base
in 7:15 at 330 fpm. I was flying at 38 mph and Paul was flying at 30 mph. I was
in 630 fpm while Paul was in 470 fpm. His sink rate was 140 fpm while mine was
210 fpm. Later we talked about him getting the VX up on a tip.
The dry fields out by Center Hill were working so it was no trick getting up
from 1,500' and getting to the second turnpoint just north of the Florida
Turnpike which also had dry fields nearby and black clouds over head. Getting
home required that we come in at 1,200' in order to be able to meet the world
record criteria. The last leg was the fastest with only one climb required to
get home with 500'above the limit.
The time was an hour and fifteen minutes, for a speed of 40.24 kmh just short of
matching the record. It was clear that just a few different choices (like
pulling in more on the final glide), it would have been a new world record. Next
time, an hour.
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The Oz Report, a near-daily, world wide hang gliding news ezine, with reports on competitions, pilot rankings, political issues, fly-ins, the latest technology, ultralight sailplanes, reader feedback and anything else from within the global HG community worthy of coverage. Hang gliding, paragliding, hang gliders, paragliders, aerotowing, hang glide, paraglide, platform towing, competitions, fly-ins. Hang gliding and paragliding news from around the world, by Davis Straub.
