At 07:23 19 February 2014, Surge wrote:
On Tuesday, 18 February 2014 12:07:20 UTC+2, Chris Rollings wrote:
That might work but I suspect it would be impossible, in the real
World,
to
get a sufficiently high degree of reliability that we did not get more
accidents from innocent gliders be jettisoned at low altitudes than we
currently get from kiting accidents.

Hi Chris

This is not a personal attack - I appreciate your valuable input but ...

With modern technology we can reliably detect pitch, roll, acceleration
of
a tug plane IMO.
e.g. My Note 2 has a magnetometer, electronic gyros, accelerometers,
barometer, and GPS. I downloaded an artificial horizon app for my Android
phone and when it blends all the sensor data you get a very reliable
pitch
and roll output.
It doesn't even experience gyro drift because it is able to compensate
using the magnetometer to sense gravity.

Another example are all the Ardupilot projects.
If they are capable of flying DIY autonomous drones around for under $300
then I think the technology is available and good enough for us to use.

Even so, I'd rather have a 1 in 1000 chance of accidentally being dumped
than kill a tug pilot and myself through a momentary lapse of
judgement/attention.

I happen to fly at the club in South Africa which had the low altitude,
tug
upset on Sunday 16th Feb 2014, resulting in the death of the tug pilot in
a
Cessna 182A.
I simply refuse to believe that we can fly to the moon and back but can't
devise a reliable automatic tow release mechanism.
How many more tug pilots around the world do we have to kill before we
devise a mechanism which works?

To detect a tug upset reliably I think one would only need:
1. To sense the tug elevator at the back stop +
2. The pitch of the tug (say 20 degrees down and increasing) +
3. The load on the rope (glider still attached).
I can't imagine the above being present in any normal operational
situation.

Paul


Paul, by the time your items 1, 2 & 3 are present it is probably too late,
the tail-plane is almost certainly stalled and even if the glider were
jettisoned at that instant, the tow-plane would probably still pitch down
another 40 or 50 degrees before recovery (I say probably, could someone
please test it with a camera plane alongside at safe altitude, done
deliberately it should be possible to pull the release at exactly the right
moment - might take three or four goes to get on exactly right).

The thing that is constantly under-estimated by those that haven't
experienced it is how quickly it all happens. LESS THAN 3 SECONDS FROM ALL
NORMAL TO ALL OVER. People take at least that long to react to something
unexpected unless it is something they have practiced frequently, certainly
not the case in kiting incidents.