In rec.aviation.student WingFlaps wrote:
On Apr 25, 3:12?am, Dylan Smith wrote:
In gliders, every glider pilot is taught "the impossible turnback" from
200 feet (which, in the typical low performance training glider, is
about equal to turning back at 600 feet in a C172).

It's the L/D that makes it much harder in a typical powered plane.
This means that all manouvers lose energy much faster. The turn back
needs at least 2 turns as well as acceleration if there is any wind.
You will note that nearly all the accidents are stall spins -a moments
thought about the situation will make you realize why this is. The
turns are made tight because there is not enough height/time for a
lazy turn.

Let's work some real numbers for a 172 at 500'. Say climb was a Vx 59
knots. The plane must first be accelerated to 65 for best glide. The
pilot carries out some trouble checks say 10s. Calls on the radio =10
s and plans his return. Note that 20s have probably elapsed. The plane
has already travelled ~0.4 miles and at a 10:1 glide ratio has lost
200' (assuming he did get it to best glide in the first place). Can
he make 2 turns and land back -no way!

It's worse than just the L/D difference would make you expect in a few
ways.

The glider's best glide speed is considerably lower. Typical best glide
speeds are 50-55kts. Also, for best performance while doing a 180 you want
to fly at min sink speed rather than best glide speed, which in a typical
glider will put you down at 40-45kts.

This speed difference has two effects, neither of them good. First, your
sink rate will be considerably higher. At 10:1 and 65kts you're sinking at
650fpm. At 30:1 and 55kts you're sinking at under 200fpm. Second, a turn
done at lower speed is smaller and faster, so you're spending more time at
that 650fpm sink rate than the glider is spending at under 200fpm.

Another speed-related effect is that the glider is taking off much faster
than his best glide speed. A typical glider tow may be at 65kts. The extra
speed is energy to be burned off in the turn. A modern medium-performance
glider will come out of a 180-degree rope-break turn at the same altitude
he started! In the Cessna in your example you have the opposite problem,
you have to trade altitude for speed just to get *up* to best glide, and
then you keep losing it at an extremely high rate.

Rope breaks are also extremely obvious when they happen, so reaction time
is essentially instantaneous. There are other glider launch emergencies
which aren't so obvious, such as the tow plane losing power, where things
can get more difficult. In the case of the piece-of-cake 200' rope break
you'll have the controls deflected in less than a second from the event
unless you really screwed up your pre-takeoff mental preparation.

In conclusion: fly gliders, it's safer!

More serious conclusion: these things are much easier in gliders because
they're basically made for it. Don't carry it over to powered flight.

--
Michael Ash
Rogue Amoeba Software