On Thu, 18 Jan 2007 17:00:16 +0000 (UTC),
(Dane Spearing) wrote:

In article ,
Nathan Young wrote:
50 ft is 99% luck. Pitch for lowest speed above stall, and pray
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
whatever is in front of you is soft. Hell, if you have really bad
luck, you might hit a tree while still in the clouds.

-Nathan

"Pitch for lowest speed above stall"?!? While this may provide for the lowest
possible forward airspeed/groundspeed, you're going to have one helluva sink
rate. In addition, your ability to manuver and flare with be severely
degrated.

Good question. First off, just to make crystal clear, I am not
advocating the low speed descent in a normal engine out scenario. In
that case, standard practice of best glide and then once visual
maneuver as required, culminating in a flare just above stall speed.

However, this scenario is quite a bit different. IMC to 50ft is
crappy weather. Unless you departed off a runway in the middle of a
flat bean field, there is a high likelyhood of the plane hitting
something (like a tree) on the way down, and if that occurs, I want
the plane's energy to be at it's minimum. Hence, my comment about
keeping the airspeed just above a stall.

I also want to mention that if the weather is IMC to 50 ft, there is a
good chance that a few clouds will go to the surface. In which case,
even in the beanfield scenario, you may hit the ground without ever
going visual.

Your point(s) about controllability at stall point and sink rate are
great ones. You probably don't want VS0 + 1mph. Maybe VS0 + 5 or 10
mph. Just enough extra speed to allow a reasonable flare (assuming
you go visual at some point before impact).

But adding speed is a big trade off, because if you hit something
before going visual, that's a lot of extra energy to dissipate on a
crash.

In my plane, best glide is 80mph. Stall is 50mph. What I was trying
to avoid was impacting something at 80mph. That's 2.5x the energy to
dissipate in the crash.

Vertical speed & forward speed vs crash survivability data would be
interesting to see. At best glide & idle throttle my Cherokee
descends at about 950fpm, which is about 11mph or the equivalent of a
free-fall from 4 feet.. I haven't checked the engine out descent rate
at VS0 + 1mph, so I have no idea what the fpm would be. That will
be a fun test next time I go flying. Previously, I did test out
70mph and 90 mph, and found minimal increase (100fpm) on the VSI.

-Nathan