Lancair crash at SnF

Shirl wrote:
WingFlaps wrote:
I've also heard a lot of BS in this thread about not having good
palces to put the plane. There is nearly always somewhere flat to put
the plane within 90 degrees of the runway centerline -even a road.
Malls have big parking lots!

I don't know about where you live, but malls here have lots of light
poles, concrete islands, park-and-rest benches and ... and ... vehicles
everywhere. And having gone through it once, I'm no longer fooled by
what *looks* "flat" at 500, or even 50 feet.

This guy ended up in somebody's yard and missed all the suburban traffic
last year. I drove through the neighborhood (about a mile from my
house) to see if it's where I'd have landed. Hmm.

http://www.nwcn.com/statenews/oregon....3a6a3952.html

" FAIRVIEW, Ore. -- A pilot flying a small plane he had purchased just
minutes earlier crash-landed in a dense suburban neighborhood near the
Troutdale Airport Wednesday after the plane's engine quit. "

tman inv@lid wrote in
:

Hold on while I try to correct some nits in what Bertie said and see
what happens

Bertie the Bunyip wrote:
Nope, the wind is going to help you in almost every way if you're
turning back.
[ many good points supporting this assertion, but... ]
also, your best LD speed is going to occur at a lower
airspeed,
Well, technically, your best LD speed is related to angle of attack,
and
not the groundspeed, so that won't change. Your best glide speed
certainly will be less...

OK, not the LD, you're right. but your best glide speed is realted to
your ground speed. To take an extreme example to illustrate this point,
imagine that your published best glide is 70 and you're trying to glide
into a 70 knot headwind. You're going nowhere. Increase your speed and
you will make headway.
In the tailwind scenario, your best glide distance over the ground will
be better at a lower speed than published. the stronger the wind, the
lower the speed required until you arive at your min sink speed.

There is no inertia involved in making a downwind turn. None.

Here's why I wonder about that. Let's suppose 65 KAS before and after
a
180 turn from a 10 KT headwind. OK, before the turn, your groundspeed
is 55KTS and after the turn your groundspeed is 75KTS. Your intertial
frame of reference is tied to the g/speed, not the a/speed. So -- the
kinetic energy of the aircraft and contents is about 33% higher
(75/55)^2. That energy is only going to come from one place with no
power -- trading in altitude (potential energy) for kinetic energy.

Nope, your inertial frame of reference owes nothing to the ground
whatsoever. None. Zero, nil zilch zippo. You ar entirely a creature of
the air and owe nothing to the ground whatsoever ( except in the
vertical, of course) The earth simply isn't that important in the bigger
scheme of things! If it were, you'd have trouble making left or right
hand tunrs in your car....


Bertie

On Apr 24, 6:41 pm, tman inv@lid wrote:
Hold on while I try to correct some nits in what Bertie said and see
what happens

Bertie the Bunyip wrote:

There is no inertia involved in making a downwind turn. None.

Here's why I wonder about that. Let's suppose 65 KAS before and after a
180 turn from a 10 KT headwind. OK, before the turn, your groundspeed
is 55KTS and after the turn your groundspeed is 75KTS. Your intertial
frame of reference is tied to the g/speed, not the a/speed. So -- the
kinetic energy of the aircraft and contents is about 33% higher
(75/55)^2. That energy is only going to come from one place with no
power -- trading in altitude (potential energy) for kinetic energy.

See the previous post. There's a change in kinetic energy, but
very, very little. Many people make the mistake of thinking that the
earth has an effect on the airplane. It does, but only vertically, by
gravity. Gravity has no horizontal Component. Like a gyroscope, which
is rigid with respect to space and cares not one bit about the earth,
the airplane's mass, as it moves in the horizontal, is affected only
by its relationship to space and the air it flies in.
That isn't to say that the earth isn't going to get in the
way a little harder. Landing downwind, as with landing into the wind,
involves transferring the weight from the wings to the wheels, and
downwind means much more groundspeed and maybe loss of control as the
roll continues at higher speed while the flight controls feel a
decreasing airspeed, or maybe the airplane will run out of runway.
Bang.
We do illusions created by drift turns with students, usually
in a strong wind and at around 500 feet, so that they can see that the
ball stays centered in the turn while they get the visual impression
that the airplane is skidding or slipping on the downwind and upwind
sides of the turn. The airspeed does not change. Not so's you could
read it. If we put the student under the hood and make him fly on
instruments while we do this, he can't tell us when he's turning into
the wind or out of it. Can't feel anything, can't see any performance
changes on the gauges.

Dan

gatt wrote in
news:ru6dnZlbZ5BGu4zVnZ2dnUVZ_qjinZ2d@integraonlin e:

Dylan Smith wrote:


We don't know it was an 'impossible turn'. We don't even know what
altitude they were at, whether the engine was still developing power
or
not, or whether the plane caught fire, or ... there simply isn't
enough
information to

Except we know they didn't make it. Assuming the pilot was reasonably
proficient, that suggests the turn couldn't be made.


No, it suggests that he probably wasn't prficient, but we don't know and
are unlikely to ever know. There's always a min height that it can be
performed from and only a lot of practice will tell you what that is for
each departure. As i've said before, only proficiency in handling an
airplane in this situation and a carefully thought out self briefing
before the departure can give even a chance of success in the turnback
manuever. Add in a bit of luck and you have it, but it's almost always
safer to go straight ahead if at all possible.


Bertie

On Apr 24, 6:41 pm, tman inv@lid wrote:
Here's why I wonder about that. Let's suppose 65 KAS before and after a
180 turn from a 10 KT headwind. OK, before the turn, your groundspeed
is 55KTS and after the turn your groundspeed is 75KTS. Your intertial
frame of reference is tied to the g/speed, not the a/speed. So -- the
kinetic energy of the aircraft and contents is about 33% higher
(75/55)^2. That energy is only going to come from one place with no
power -- trading in altitude (potential energy) for kinetic energy.

In your world, it's gonna be pretty hard for a sailplane to circle in
a drifting thermal. In my world, it's not a problem.

gatt wrote in
news:T-Sdnb-eo8vLtIzVnZ2dnUVZ_tWtnZ2d@integraonline:

Buttman wrote:
On Thu, 24 Apr 2008 17:05:06 +0200, Stefan sayeth:

Brian schrieb:

Your right in that many aircraft it is possible. But the problem is
it isn't possible for many pilots when the engine quits. It is not
a maneuver that is routinly practiced.
Now this problem could be solved.

You're suggesting instructors practice engine failures with their
students on takeoff? Oh boy, better hope Dudly doesn't see this...

One way to practice this would be to establish a "runway altitude" at,
say, 1000ft AGL, get the airplane into takeoff configuration on
heading at that altitude over a road or something, simulate a failure
at a specified altitude--say, 1,500 feet--and see what altitude you're
at when you get back to your reciprocal heading. If it's above your
starting altitude, you made it.

Wind, density altitude and aircraft weight are significant variables.

Of course, a proficient pilot will have considered all these variables
as well as the terrain downrange before takeoff, so they already know
what they will do if the engine quits at a specific altitude. On
probably as many checkrides and flight reviews as not, the instructor
has asked me what I will do if I lose power on takeoff so I already
know
where there transmission lines are, about how far it is to the lake,
etc.

-c


More importantly, perhaps, is the fact that if you make nice gentle
turns in an average lightplane, you simply won't make it. You have to
make the turn at a very high angle of bank to have even a hope of making
it in time. If you make it at say, 30 deg of bank at about 65 you're
going to lose the guts of 800 feet just manuevering to line up with the
runway if you fly the airplane accurately. You're going to be very low
at the end of this manuever to say the least. The best way to do it is
with a steep bank. Very steep. This will, of course, mean a high sink
rate, but the time required to make the turn will be cut drastically and
you'll be closer to the centerline when you've come about, so less time
and alt wasted trying to get lined up. To do this you must be absolutely
completely comfortable doing a steep power off turn at a reltively low
airspeed when you do it. Not imagining you can do it based on experience
doing steep turns with the power on, you have to be able to
simultaneously offload the wing at a rate that won't get the nose too
low as to get an excessive alt loss and make this drastic turn at the
same time without stalling. All this while your brain has become akin to
that of a lizard looking a rather big snake. IOW, you have to have
practiced this and other aerobatic manuevers so that they are second
nature. It can be done and it can be done in almost any airplane, but it
requires a lot of practice, experience, careful planning and a lot of
luck. Better to go straight ahead if you can.


Bertie

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

WingFlaps wrote:

A Lancair crashed just moments after takeoff here in Mesa, Arizona,
today, too. Plane was headed for California. There was smoke trailing
from the plane on takeoff and controllers cleared them to turn back
around and land. They tried -- they made the left turn but crashed into
the orange orchard. Three fatalities, all in their late 20s. Sympathies
and prayers to the families.

When will pilots learn to stop trying to do the impossible turn... and
go for a straight ahead landing on soemthing horizontal?

I saw the local news report and the suggestion was that he hit where
he did to avoid populated areas. A picture shown did suggest that
straight ahead was problematic.

Ron Lee

In rec.aviation.student tman inv@lid wrote:
Here's why I wonder about that. Let's suppose 65 KAS before and after a
180 turn from a 10 KT headwind. OK, before the turn, your groundspeed
is 55KTS and after the turn your groundspeed is 75KTS. Your intertial
frame of reference is tied to the g/speed, not the a/speed. So -- the
kinetic energy of the aircraft and contents is about 33% higher
(75/55)^2. That energy is only going to come from one place with no
power -- trading in altitude (potential energy) for kinetic energy.

This simply does not make any sense.

Kinetic energy, like velocity, is a relative quantity. You cannot look at
an object and say, "it has X joules of KE". You can only talk about KE
relative to some frame of reference. Just like velocity.

So forget about KE. It's in the same boat as velocity, so look at
velocity. You make a turn and suddenly you gain a bunch of groundspeed.
Where does the extra speed come from? It comes because you're maneuvering
relative to a medium, the air, which is itself moving. Your KE relative to
that medium is exactly the same as it was, so no energy has to come from
anywhere.

--
Michael Ash
Rogue Amoeba Software

On Fri, 25 Apr 2008 01:27:52 +0000 (UTC), Bertie the Bunyip
wrote in :

The best way to do it is with a steep bank. Very steep.


The bank angle may be quantified:


http://groups.google.com/group/rec.a...1d80a2e846a88b
John T. Lowry

Best turnaround bank angle phi (least altitude loss per angle
turned through) for a gliding airplane is given by:

cos(phi) = (sqrt(2)/2)*sqrt(1-k^2)

where k = CD0/CLmax + CLmax/(pi*e*A)
where CD0 is the parasite drag coefficient,
CLmax is the maximum lift coefficient for the airplane's flaps
configuration,
e is the airplane efficiency factor, and
A is the wing aspect ratio.

I know most ng readers hate those darned formulas, but that's the
way the world works. For GA propeller-driven airplanes, k is a
small number (0.116 for a Cessna 172, flaps up) and so the best
turnaround bank angle is very closely the 45 degrees cited by
Rogers and, much earlier, by Langewiesche (Stick and Rudder,
p. 358). For the above Cessna, for instance, it's 45.4 degrees.
For a flamed-out jet fighter, however, things are considerably
different. The formulas above, along with formulas for the banked
stall speed, for banked gliding flight path angle, and for the
minimum altitude loss in a 180-degree turn, can all be found in my
recent book Performance of Light Aircraft, pp. 294-296.
The following seven pages then treat the return-to-airport
maneuver, rom start of the takeoff roll to contact with the runway
or terrain, in excruciating detail. Including wind effects, the
typical four-second hesitation when the engine stops, etc.

John. -- John T. Lowry, PhD Flight Physics; Box 20919; Billings MT
59104 Voice: 406-248-2606