Finish Gate Accident no. 2

Hahaha...

I'l try this in the 2-33 at Vne (about 80 knots) and
see if I get over 200 ft 'regained'

I doubt it. But then again, that's maybe off topic.
I think your calculations are for gliders that don't
fly like they have a parachute attached to the back,
right?


I'm sure even the Blanik will get numbers fairly close
to what you write, but I'lll give it a go (at altitude).

Passengers love to 'zoom' so this should be fun...

At 06:30 27 March 2005, Bruce Hoult wrote:
In article ,
M B wrote:

It occurs to me that if someone is on final glide
at
the end of a competition, they may pick a speed (like
85 knots) which their computer says is optimal for
points, but which is both:

1) too fast for a rolling finish/landing
and
2) too slow for a pull up, turn around, and landing.

Is that an accurate assessment? Would a competition
pilot be put in a situation where he must decide between
points and safety of the landing?

It seems to me that 85 knots is a little too slow to
do a full circuit
from, but plenty do do a 180, or a 360, or an abbreviated
circuit
similar to a rope-break exercise.

Someone gave a figure of 9 ft of pullup for each knot
of speed. That's
about right for speeds around 110 knots, but is a gross
overestimate for
speeds around 80 or 90 knots (and an underestimate
for higher speeds).

The true numbers are quadratic. If you want a rule
of thumb I suggest
the following:

take speed in knots, double it, drop off the last
digit,
square what is left giving height for a pull-up in
feet.

This calculation gives just over 90% of the theoretical
maximum pull-up,
which is proabably not a bad figure taking into the
drag loses.

Note that this is for a pull up to a zero speed hammerhead.
For a pull
up to flying speed you need to subtract the appropriate
height for your
circuit speed e.g. 100 ft for 50 knots.


examples, from zero-height finish, 50 knot circuit
speed:

50 knots - 100 - 10, squared = 100 ft gain, 0 ft AGL
@ 50 kt
60 knots - 120 - 12, squared = 144 ft gain, 44 ft
AGL @ 50 kt
80 knots - 160 - 16, squared = 256 ft gain, 156 ft
AGL @ 50 kt
90 knots - 180 - 18, squared = 324 ft gain, 224 ft
AGL @ 50 kt
100 knots - 200 - 20, squared = 400 ft gain, 300 ft
AGL @ 50 kt
120 knots - 240 - 24, squared = 576 ft gain, 476 ft
AGL @ 50 kt
150 knots - 300 - 30, squared = 900 ft gain, 800 ft
AGL @ 50 kt

A pull up from 85 knots to 50 knots will give you about
a 200 ft height
gain, plus whatever height your finish was at. We
give students rope
breaks at 200 ft, right? So a competent and alert
pilot should have no
trouble deciding whether to land straight ahead after
the pull up or do
an abbreviated circuit.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

Mark J. Boyd