gliding back to your departure airport

[Harold]

If a small single engine plane can out-climb its engine-out glide ratio from
take off through the top of climb point, wouldn't it follow that it can
always theoretically make it back to the departure airport in the event of
engine failure ? Assuming straight out departure, no wind, and the altitude
loss in the 180 turnback is offset by the runway portion you didn't use. If
my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I be
guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?

[Roger Tracy]

This is a good thing to test at altitude and know ahead of time. There's
going to be a certain height AGL that you just can't get turned around.
You should know what that is for your plane.


"Harold" > wrote in message
...
> If a small single engine plane can out-climb its engine-out glide ratio
from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ? Assuming straight out departure, no wind, and the
altitude
> loss in the 180 turnback is offset by the runway portion you didn't use.
If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>
>

[Roger Long]

Altitude loss to get a 172 turned around after practice is about 600 feet.
If the pilot is surprised, panicked, or out of practice, it will be more.
If the pilot it very surprised, panicked, and out of practice, it may be
exactly equal to the altitude the maneuver was started at when he stalls due
to a combination of too much bank and pull on the yoke.

--
Roger Long

[Bob Gardner]

Keep in mind that it will not be a 180 degree turn but more like 210 degrees
(unless you plan to make your power-off landing parallel to runway surface).
There have been many, many studies of the "Impossible Turn." Google that
term and you will learn a lot.

Bob Gardner

"Harold" > wrote in message
...
> If a small single engine plane can out-climb its engine-out glide ratio
from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ? Assuming straight out departure, no wind, and the
altitude
> loss in the 180 turnback is offset by the runway portion you didn't use.
If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>
>

[Harold]

Well obviously, but I'm not talking about in the pattern area like the
Impossible Turn is. I'm talking about 10 minutes after departure at 7k feet
where the departure airport, if you can make it, is the best landing option.
Then for all intents and purposes its a 180 degree turn.

> Keep in mind that it will not be a 180 degree turn but more like 210
degrees
> (unless you plan to make your power-off landing parallel to runway
surface).
> There have been many, many studies of the "Impossible Turn." Google that
> term and you will learn a lot.
>
> Bob Gardner
>
> "Harold" > wrote in message
> ...
> > If a small single engine plane can out-climb its engine-out glide ratio
> from
> > take off through the top of climb point, wouldn't it follow that it can
> > always theoretically make it back to the departure airport in the event
of
> > engine failure ? Assuming straight out departure, no wind, and the
> altitude
> > loss in the 180 turnback is offset by the runway portion you didn't use.
> If
> > my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
> be
> > guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
> >
> >
>
>

[Peter Duniho]

"Harold" > wrote in message
...
> [...] If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?

Do you descend at 700fpm gliding at 85 knots (which you should reference as
*indicated* airspeed, not true) with the wings level? Or did you verify
that descent rate in a turn?

Several factors prevent the simplistic analysis you've made from being
valid:

* The turn itself increases descent rate

* You need to turn a net of closer to 270 degrees: 225 to get you on an
intercept course back to the runway, then another 45 degrees the other
direction to align yourself for touchdown.

* Typically you are climbing into a headwind; that becomes a tailwind
halfway through your turn and through the remainder of the descent. The
tailwind will either push you past the runway, or you need to steepen your
descent by increasing the descent rate. Either way, that interferes with
the basic "if I climb at such-and-such a rate, then instantly turn 180
degrees and descend at a different rate, can I make it back to the runway"
simplification. Assuming "no wind" conditions doesn't make sense, because
that assumption is almost never correct and the consequence is significant.

Don't forget the reaction time it takes to start the turn, and the time
spent at something other than best glide airspeed. For the vast majority of
pilots, a large proportion of the post-engine-failure flight will be done
quite a bit away from optimally.

If you have a hard time believing this, it's easy enough to experiment.
Find yourself a nice quiet airport where you can depart straight out. Climb
straight out to 2000' AGL, then cut the power. Wait a second or two (since
you won't be surprised by the power cut), then go ahead and start your turn
back to the runway. Note the altitude loss at the point at which you are
back aligned with the runway. This will give you the absolute *minimum*
altitude you might successfully attempt such a turn-back.

For extra credit, time the post-power-cut flight, noting your airspeed as
well. This will allow you to figure out how far you actually flew during
the descent, which will give you an idea of whether you'd have actually had
enough runway left to land on by the time you got all set up. For extra
accuracy, take someone along to keep track of the actual airspeed, or use a
GPS to track the experiment (to get distance directly, rather than depending
on speed over time).

Finally, keep in mind that not all airplanes have the characteristic yours
does. In fact, I'd say it's unusual to find an airplane that climbs and
descends at exactly the same airspeed and vertical speed. Especially
powerful aircraft will climb more steeply than they descend, while slower,
lower-powered airplanes will climb less steeply than they descend.

Pete

[Jim]

Due to the vertical lift loss during your more than 180 degree turn back to
the airport, you will loose more than 700fpm and your glide range will
decrease if you try to maintain your best glide speed during your turn. I
believe Barry Schiff wrote that this maneuver is best done at a fairly high
rate of turn which involves an approximate 45-50 degree bank to keep the
radius of turn small. This will enable you to then level the wings and then
obtain your best glide speed in the shortest time while getting you back to
the runway in the shortest distance. Not a maneuver for the non-proficient
or the startled and hesitant.
--
Jim Burns III

Remove "nospam" to reply

"Harold" > wrote in message
...
> If a small single engine plane can out-climb its engine-out glide ratio
from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ? Assuming straight out departure, no wind, and the
altitude
> loss in the 180 turnback is offset by the runway portion you didn't use.
If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>
>

[Peter Duniho]

"Harold" > wrote in message
...
> Well obviously, but I'm not talking about in the pattern area like the
> Impossible Turn is. I'm talking about 10 minutes after departure at 7k
feet
> where the departure airport, if you can make it, is the best landing
option.
> Then for all intents and purposes its a 180 degree turn.

To my knowledge, no one has ever said you can't. Other than aircraft that
cannot climb as steeply as they descend (and there are a number of aircraft
that are like that), obviously after a 10 minute climb, it would be very
likely you could make it back to your original departure airport.

I would never say "guaranteed". Other than aircraft performance, there are
still other reasons you wouldn't be able to make it. For example, climbing
with a tailwind will hinder your ability to make it back to the airport
(just because you take off into the wind, that doesn't mean you'll be
climbing out into the wind, even if you depart straight out).

So, a literal answer to your question is "no", you cannot guarantee that you
can make it back. However, it's true that for many aircraft, once you've
climbed that far, the original departure airport is often going to be a very
good choice for an emergency landing site, at least shortly after takeoff.

Does *that* answer your question?

Pete

[Larry Dighera]

On Tue, 21 Oct 2003 20:02:00 GMT, "Harold" > wrote
in Message-Id: >:

>If a small single engine plane can out-climb its engine-out glide ratio from
>take off through the top of climb point, wouldn't it follow that it can
>always theoretically make it back to the departure airport in the event of
>engine failure ? Assuming straight out departure, no wind, and the altitude
>loss in the 180 turnback is offset by the runway portion you didn't use. If
>my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I be
>guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>

The mathematics of turning back to the airport have been thoroughly
discussed in the newsgroup a while back. I suggest you do a
www.deja.com search for articles authored by John Lowry on the
subject. Here's an example:

http://groups.google.com/groups?selm=7bf3bb%24h91%241%40news.mcn.net&oe=UTF-8&output=gplain

From: John T. Lowry )
Subject: Re: Min Turnaround Alt. on Single Engine Aircraft-Engine
Failure Question
Newsgroups: rec.aviation.piloting
Date: 1999/02/26


Dear Mike, Henrik, and All:
For the single engine-out return-to-airport maneuver, all the
various parameters (aircraft weight and flaps settings, runway length
and elevation, wind speed and direction) matter. But a crucial
performance number is, instead of just best glide ratio (which is
important once the turn is made) or minimum sink rate, the maximum
turn rate PER altitude lost, dTheta/dh. As close to (banked) stall as
possible. That rate is:

Max(dTheta/dh) =
-g*Rho*S*CLmax*sin(theta)*sqrt(cos^2(theta)+k^2)/(2*W*k)

where g is 32.2 ft/sec^2, Rho is density, S wing area, W weight, and

k = CD0/CLmax + CLmax/(Pi*e*A)

where CD0 is the parasite drag coefficient, e the airplane efficiency
factor, and A the wing aspect ratio. The optimum bank angle is just a
little (except for flamed-out jets) OVER 45 degrees and is given by

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

You'll find a full discussion in Chapter 9, Glide Performance, of my
forthcoming Performance of Light Aircraft published by AIAA.

John.

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

--------------------------------------------------------
Here's the formula for best glide

http://groups.google.com/groups?selm=79k5ds%24596%241%40news.mcn.net&oe=UTF-8&output=gplain

From: "John T. Lowry" >
Subject: Re: Formula for Vbg
Date: 1999/02/07
Message-ID: >#1/1
References: >
>
X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4
Organization: Montana Communications Network
Newsgroups: rec.aviation.piloting


Dear Phil, and All:
There is a fixed relationship between speed for best glide Vbg and
speed for minimum descent rate Vmd -- Vbg = 1.3161*Vmd -- but (since
you probably don't have Vmd) that won't help you much.
Vbg depends on the drag characteristics of the airplane, depending
on 1) W/sigma (W gross weight), 2) reference wing area S, 3)wing
aspect ratio A, 4)parasite drag coefficient CD0, and 5) airplane
efficiency factor e, according to
Vbg = sqrt(2*W/sigma*S)*(Pi*e*A*CD0)^-1/4

If you're willing to cut the engines and feather the props, to find
Vbg experimentally, here's a rough outline of the procedure. Go to
some nice high altitude and pick a vertical interval of pressure
altitudes, say for purposes of illustration from 14000 ft down to
13000 ft. Time repeated glides down through that interval and record
the product KCAS*delta_t, where delta_t is the time needed for the
glide. When you've found, by trial and error, the speed V which
maximizes that product, that speed is Vbg.

John

----------------------------------------------------

[Bob Gardner]

That wasn't implicit in your post (although "top of climb" is a heck of a
hint). Most such questions deal with failure during the initial climb.

Bob Gardner

"Harold" > wrote in message
...
> Well obviously, but I'm not talking about in the pattern area like the
> Impossible Turn is. I'm talking about 10 minutes after departure at 7k
feet
> where the departure airport, if you can make it, is the best landing
option.
> Then for all intents and purposes its a 180 degree turn.
>
> > Keep in mind that it will not be a 180 degree turn but more like 210
> degrees
> > (unless you plan to make your power-off landing parallel to runway
> surface).
> > There have been many, many studies of the "Impossible Turn." Google that
> > term and you will learn a lot.
> >
> > Bob Gardner
> >
> > "Harold" > wrote in message
> > ...
> > > If a small single engine plane can out-climb its engine-out glide
ratio
> > from
> > > take off through the top of climb point, wouldn't it follow that it
can
> > > always theoretically make it back to the departure airport in the
event
> of
> > > engine failure ? Assuming straight out departure, no wind, and the
> > altitude
> > > loss in the 180 turnback is offset by the runway portion you didn't
use.
> > If
> > > my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't
I
> > be
> > > guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
> > >
> > >
> >
> >
>
>

[BTIZ]

Most gliders can do this and the pilots train to that standard..

Departure problems below 200ft AGL, tow plane power problems.. rope breaks
or tow hook failures.. and the idea is to land straight ahead as quickly as
possible and get stopped.

Above 200ft AGL (which most glider/tow combinations can get to about 3000ft
after start of take off roll), if the rope breaks, tow plane says.. GET
OFF!!.. the glider pilot can pitch down for airspeed and begin a turn back
to the departure runway.. land opposite the direction of take off and have
enough energy to roll back to the starting point.

A nice tow pilot will allow the tow to "Drift down wind the cross wind" on
climb out, so if something does happen the glider can turn into the wind
when returning to the runway.. turning away from the wind can push the
glider to far away (tailwind on base) and make returning to the runway more
difficult.

This maneuver is part of the practical test standards, though most DE's will
wait until 300ft or higher and most CFIGs will review the procedure on BFRs.

Our "Training glider" has a L/d of 23-1. Schweizer 2-33.

BT

"Harold" > wrote in message
...
> If a small single engine plane can out-climb its engine-out glide ratio
from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ? Assuming straight out departure, no wind, and the
altitude
> loss in the 180 turnback is offset by the runway portion you didn't use.
If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>
>

[dennis]

The glider has a couple of things going for it. Power planes are seldom over
12:1 glide ratio and it is achieved at a higher speed than the glider.
This means that the power plane covers about half the THEORETICAL glide
distance of the glider. Said loudly.

The speed ratio between the wind and the aircraft is a factor. A given wind
speed will be a higher percentage of the glider's best glide speed and will
result in a greater advantage to it's L/D downwind compared to a power plane
with the same wind. The wind also works to advantage for the glider's on tow
part by decreasing the distance that it covers on climb, compared to a power
plane at typical climb speeds.

Finally, for some ancient and illogical reason, power plane standard procedure
is to stay on center line of the runway for climbout. It's considered bad form
to put yourself in a safer position for a turn back to the field. The
exception is an IFR departure. They typically maintain runway heading. Lots
of luck making a turn back under IFR.

You subtract reaction time, reconfiguration time, screw around trying to get
the thing to run, and it is very, very unlikely that a power plane will get
back to the runway at any time during their climb out. Unless it is a long
runway and you started from the end.




In article <afjlb.63635$La.24804@fed1read02>, "BTIZ"
> wrote:
>Most gliders can do this and the pilots train to that standard..
>
>Departure problems below 200ft AGL, tow plane power problems.. rope breaks
>or tow hook failures.. and the idea is to land straight ahead as quickly as
>possible and get stopped.
>
>Above 200ft AGL (which most glider/tow combinations can get to about 3000ft
>after start of take off roll), if the rope breaks, tow plane says.. GET
>OFF!!.. the glider pilot can pitch down for airspeed and begin a turn back
>to the departure runway.. land opposite the direction of take off and have
>enough energy to roll back to the starting point.
>
>A nice tow pilot will allow the tow to "Drift down wind the cross wind" on
>climb out, so if something does happen the glider can turn into the wind
>when returning to the runway.. turning away from the wind can push the
>glider to far away (tailwind on base) and make returning to the runway more
>difficult.
>
>This maneuver is part of the practical test standards, though most DE's will
>wait until 300ft or higher and most CFIGs will review the procedure on BFRs.
>
>Our "Training glider" has a L/d of 23-1. Schweizer 2-33.
>
>BT
>
>"Harold" > wrote in message
...
>> If a small single engine plane can out-climb its engine-out glide ratio
>from
>> take off through the top of climb point, wouldn't it follow that it can
>> always theoretically make it back to the departure airport in the event of
>> engine failure ? Assuming straight out departure, no wind, and the
>altitude
>> loss in the 180 turnback is offset by the runway portion you didn't use.
>If
>> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
>be
>> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>>
>>
>
>

[David Hill]

dennis wrote:
<snip>
> You subtract reaction time, reconfiguration time, screw around trying to get
> the thing to run, and it is very, very unlikely that a power plane will get
> back to the runway at any time during their climb out. Unless it is a long
> runway and you started from the end.

After getting my private, I was wondering about this, particularly
because the airport I usually fly out of (PDK) is surrounded by
development that leaves no place, at any time of day, to even dream of
setting down safely in the event of an engine failure.

Not getting answers that satisfied me, I went out and did some tests
myself, at altitude. Used GPS, a partner to log altitudes and
waypoints, etc. Came to the conclusion that if everything went
*perfect*, and you *knew* it was going to happen, it would take 500' agl
to make it back, in a Warrior.

But what I did was pick the brains of my friends who were glider pilots,
worked on Vms turns, high bank angle turns, popping 10 degrees of flap
for the turn and popping it out for the glide, etc., etc. After
practicing all that, and knowing what was coming, 500' was the best I
could do. Which to me means 800'-1000' in real life, if you practiced
it a lot.

It was an eye-opener for me to see how little margin for error I have
operating out of PDK. It has changed my standard departure. I climb at
Vx to pattern altitude, just to gain the most altitude while I'm still
within reach of the airport boundaries. The one good thing about PDK is
it has 4 runways aligned 3 different ways, and lots of taxiways and ramp
space between them, so just getting back to the airport itself you have
a better chance of putting it down safely, if not on a runway.

Plus the crash trucks don't have as far to go. :-)

--
David Hill
david at hillREMOVETHISfamily.org
Sautee-Nacoochee, GA, USA

filters, they're not just for coffee anymore
The following needn't bother to reply, you are filtered:
Juan E Jimenez, Barnyard BOb, Larry Smith, John Nada

[David Megginson]

David Hill > writes:

> After getting my private, I was wondering about this, particularly
> because the airport I usually fly out of (PDK) is surrounded by
> development that leaves no place, at any time of day, to even dream of
> setting down safely in the event of an engine failure.

Confirm this with someone who knows better, but from what I've heard,
you need only about 20 ft of deceleration to have a chance of
surviving a landing in a Cherokee/172/Musketeer-class aircraft. That
suggests that setting down in a developed area (an unoccupied part,
preferably) might be survivable.

To take a real-world example, an instructor taking a sightseeing
flight out of Buttonville (near Toronto) had an engine failure over
solid development, so she set the plane down deliberately in a grove
of small trees on the front lawn of the IBM plant. The trees smashed
up the plane nicely, but in doing so, they dissipated enough energy
that she and her passengers walked away. Here's the story (with
photo):

http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1065737415378&call_pageid=968332188492&col=968793972154

I read afterwards that she went back to work later that day.


All the best,


David

[G.R. Patterson III]

Harold wrote:
>
> If a small single engine plane can out-climb its engine-out glide ratio from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ?

Sure, except that you have to get turned around first. There is always some
altitude below which you will not be able to return to the airport. This tends
to be between 600 and 900' AGL in a typical powered aircraft.

George Patterson
To a pilot, altitude is like money - it is possible that having too much
could prove embarassing, but having too little is always fatal.

[Tom Pappano]

David Hill wrote:
> dennis wrote:
> <snip>
>
>
> After getting my private, I was wondering about this, particularly
> because the airport I usually fly out of (PDK) is surrounded by
> development that leaves no place, at any time of day, to even dream of
> setting down safely in the event of an engine failure.

I would think, in a "172" or similar class airplane, if you have your
seatbelts and shoulder harnesses on, flaps down, minimum controllable
airspeed, and *maintain control*, you should be able to land on (or
into) almost anything and survive with minor injury. I know of two
landings on top of houses that were both "walk aways".

Another engine fail on takeoff landing here was at night into a
park full of mature oak trees. Front seat guys were seriously banged
up, but they also were not wearing seat belts. Three rear seat pax,
also unbelted, received minor injuries.

Tom Pappano, PP-ASEL-IA

[alexy]

"Harold" > wrote:

>If a small single engine plane can out-climb its engine-out glide ratio from
>take off through the top of climb point, wouldn't it follow that it can
>always theoretically make it back to the departure airport in the event of
>engine failure ? Assuming straight out departure, no wind, and the altitude
>loss in the 180 turnback is offset by the runway portion you didn't use.
I'm not clear what you mean by that.
> If
>my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I be
>guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>
If by your statement above, you mean that the runway is long enough
that if you can't turn back, you can land straight ahead, then of
course your statement is trivially true. If not, how can you turn back
from 10'?
--
Alex
Make the obvious change in the return address to reply by email.

[Larry Dighera]

On Wed, 22 Oct 2003 01:52:18 GMT, Tom Pappano > wrote
in Message-Id: >:

>Front seat guys were seriously banged up, but they also were not wearing
>seat belts. Three rear seat pax, also unbelted, received minor injuries.

Life may be "like a box of chocolates for some folks," but the laws of
physics are seldom broken. :-)

Anyone who doesn't faithfully use lap and shoulder belts, is a damn
fool.

[BTIZ]

True on all counts...

BT

"dennis" > wrote in message
k.net...
> The glider has a couple of things going for it. Power planes are seldom
over
> 12:1 glide ratio and it is achieved at a higher speed than the glider.
> This means that the power plane covers about half the THEORETICAL glide
> distance of the glider. Said loudly.
>
> The speed ratio between the wind and the aircraft is a factor. A given
wind
> speed will be a higher percentage of the glider's best glide speed and
will
> result in a greater advantage to it's L/D downwind compared to a power
plane
> with the same wind. The wind also works to advantage for the glider's on
tow
> part by decreasing the distance that it covers on climb, compared to a
power
> plane at typical climb speeds.
>
> Finally, for some ancient and illogical reason, power plane standard
procedure
> is to stay on center line of the runway for climbout. It's considered bad
form
> to put yourself in a safer position for a turn back to the field. The
> exception is an IFR departure. They typically maintain runway heading.
Lots
> of luck making a turn back under IFR.
>
> You subtract reaction time, reconfiguration time, screw around trying to
get
> the thing to run, and it is very, very unlikely that a power plane will
get
> back to the runway at any time during their climb out. Unless it is a long
> runway and you started from the end.
>
>
>
>
> In article <afjlb.63635$La.24804@fed1read02>, "BTIZ"
> > wrote:
> >Most gliders can do this and the pilots train to that standard..
> >
> >Departure problems below 200ft AGL, tow plane power problems.. rope
breaks
> >or tow hook failures.. and the idea is to land straight ahead as quickly
as
> >possible and get stopped.
> >
> >Above 200ft AGL (which most glider/tow combinations can get to about
3000ft
> >after start of take off roll), if the rope breaks, tow plane says.. GET
> >OFF!!.. the glider pilot can pitch down for airspeed and begin a turn
back
> >to the departure runway.. land opposite the direction of take off and
have
> >enough energy to roll back to the starting point.
> >
> >A nice tow pilot will allow the tow to "Drift down wind the cross wind"
on
> >climb out, so if something does happen the glider can turn into the wind
> >when returning to the runway.. turning away from the wind can push the
> >glider to far away (tailwind on base) and make returning to the runway
more
> >difficult.
> >
> >This maneuver is part of the practical test standards, though most DE's
will
> >wait until 300ft or higher and most CFIGs will review the procedure on
BFRs.
> >
> >Our "Training glider" has a L/d of 23-1. Schweizer 2-33.
> >
> >BT
> >
> >"Harold" > wrote in message
> ...
> >> If a small single engine plane can out-climb its engine-out glide ratio
> >from
> >> take off through the top of climb point, wouldn't it follow that it can
> >> always theoretically make it back to the departure airport in the event
of
> >> engine failure ? Assuming straight out departure, no wind, and the
> >altitude
> >> loss in the 180 turnback is offset by the runway portion you didn't
use.
> >If
> >> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't
I
> >be
> >> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
> >>
> >>
> >
> >

[BTIZ]

George.. where do you get all these neat quotes for your sig line

BT

"G.R. Patterson III" > wrote in message
...
>
>
> Harold wrote:
> >
> > If a small single engine plane can out-climb its engine-out glide ratio
from
> > take off through the top of climb point, wouldn't it follow that it can
> > always theoretically make it back to the departure airport in the event
of
> > engine failure ?
>
> Sure, except that you have to get turned around first. There is always
some
> altitude below which you will not be able to return to the airport. This
tends
> to be between 600 and 900' AGL in a typical powered aircraft.
>
> George Patterson
> To a pilot, altitude is like money - it is possible that having too
much
> could prove embarassing, but having too little is always fatal.

[David Hill]

David Megginson wrote:
> Confirm this with someone who knows better, but from what I've heard,
> you need only about 20 ft of deceleration to have a chance of
> surviving a landing in a Cherokee/172/Musketeer-class aircraft. That
> suggests that setting down in a developed area (an unoccupied part,
> preferably) might be survivable.

Tom Pappano wrote:
> I would think, in a "172" or similar class airplane, if you have your
> seatbelts and shoulder harnesses on, flaps down, minimum controllable
> airspeed, and *maintain control*, you should be able to land on (or
> into) almost anything and survive with minor injury. I know of two
> landings on top of houses that were both "walk aways".

I've heard this too. And it makes sense to me. And I would shoot for
trees if that were the best option and I had time and altitude to pick
the spot. The problem with the area surrounding PDK is that it is so
densely developed one would be hard pressed, especially in a low
altitude emergency situation, to pick an appropriate and unoccupied place.

I personally would not deliberatly shoot for a house; can't tell who's
inside.

The biggest issue for me around PDK is powerlines. There are multiple
multilane roads on three sides of PDK, but even if they weren't *always*
occupied by heavy traffic, they are criss-crossed with power lines every
few hundred feet. Snag a powerline, and you've lost control, at the
very least.

Take a look at www.terraserver.com; search for Lat: 33.873596938 and
Lon: -84.30184815. All the trees you see surrounding the airport are in
someone's (tiny) yard, except for a stretch just off the end of 27 (the
least used runway). There's a golf course off west, but if you can
glide to that, you're high enough to get back to the airport; plus it's
at 90 degrees to the main runways anyway.

Like I said, I figure in this particular place, the best way to increase
my chances of survival is get as much altitude within the shortest
distance as possible.

--
David Hill
david at hillREMOVETHISfamily.org
Sautee-Nacoochee, GA, USA

filters, they're not just for coffee anymore
The following needn't bother to reply, you are filtered:
Juan E Jimenez, Barnyard BOb, Larry Smith, John Nada

[Newps]

There was a good article by Barry Schiff last year in AOPA Pilot about
this. I went out and tried it in my 182. I had originally thought that
you would need a healthy shove forward on the controls to keep from
stalling. This is not the case, the plane will simply nose down to
maintain the trimmed airspeed. I need 200 feet to complete a 180 and
another 150 feet to get back to the departure runway. That is only
using a 45 degree bank, the article shows that 60 degrees is optimal.



Roger Tracy wrote:

> This is a good thing to test at altitude and know ahead of time. There's
> going to be a certain height AGL that you just can't get turned around.
> You should know what that is for your plane.
>
>
> "Harold" > wrote in message
> ...
>
>>If a small single engine plane can out-climb its engine-out glide ratio
>
> from
>
>>take off through the top of climb point, wouldn't it follow that it can
>>always theoretically make it back to the departure airport in the event of
>>engine failure ? Assuming straight out departure, no wind, and the
>
> altitude
>
>>loss in the 180 turnback is offset by the runway portion you didn't use.
>
> If
>
>>my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
>
> be
>
>>guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>>
>>
>
>
>

[Newps]

Larry Dighera wrote:


>
> The mathematics of turning back to the airport have been thoroughly
> discussed in the newsgroup a while back. I suggest you do a
> www.deja.com search for articles authored by John Lowry on the
> subject.

Yeah he's a genius. That's why he keeps wrecking aircraft.

[Jeff Franks]

> If by your statement above, you mean that the runway is long enough
> that if you can't turn back, you can land straight ahead, then of
> course your statement is trivially true. If not, how can you turn back
> from 10'?


Do it the way the Space Shuttle does it (theoretically). If they have an
abort between liftoff and 4 min 20 sec (I think), they are supposed to
execute an RTLS abort (Return to Launch Site). Problem is that no matter
what the situation is, they can't do squat until the SRB's are off the
stack. Once those puppies are lit, your in for a 2 minute ride whether you
want one or not.

After the SRB's seperate, the shuttle is supposed to fly around with just
the External Tank attached for long enough to burn up fuel and then they cut
the engines (if there are any burning) and drop the tank, then glide safely
home (again...theoretically). After the 4:20, I guess they file a missed
approach and are diverted.....to SPAIN!!!!

I truly hope that it is never required, but I've always wondered if this
thing would actually work. We all know that the Shuttle has a glide ratio
somewhere between my Ford Ranger and a brick 0, so it would be interesting
to see how this thing would actually play out.

I don't think this procedure is ever going to make it into our C150 POH's.
But who knows. 100 years ago, we weren't supposed to be able to fly either.
Hrmmm. "Introducing the all new 2067 Model Cessna 150, complete with your
choice of Wheel Pants or JATO packs....."


Jeff

wow...sorry, way off topic........More on RTLS if you care:

http://makeashorterlink.com/?G2B044B46

[Mike Rapoport]

Not unless you are planning to glide straight ahead. You will lose a lot of
altitude in the turn.

Mike
MU-2


"Harold" > wrote in message
...
> If a small single engine plane can out-climb its engine-out glide ratio
from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ? Assuming straight out departure, no wind, and the
altitude
> loss in the 180 turnback is offset by the runway portion you didn't use.
If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I
be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?
>
>

[G.R. Patterson III]

BTIZ wrote:
>
> George.. where do you get all these neat quotes for your sig line

This particular one comes from "To War in a Stringbag", by Commander Lamb, RN.
IIRC, he was relating an incident early in the war in which he was scud-running
in Scotland.

When I run into something in my reading that I like, I change my sig file for
a while. When I get tired of it, I'll change it to one of my favorites, such
as this one.

George Patterson
To a pilot, altitude is like money - it is possible that having too much
could prove embarassing, but having too little is always fatal.

[Wolfgang K.]

"Newps" > schrieb im Newsbeitrag
news:qnnlb.838361$YN5.947383@sccrnsc01...
> There was a good article by Barry Schiff last year in AOPA Pilot about
> this. I went out and tried it in my 182. [schnipp]

i'd be interested in the article - any link to that?

regards from loww, vie, vienna, austria
wolfgang

[John Galban]

"Harold" > wrote in message >...

> Well obviously, but I'm not talking about in the pattern area like the
> Impossible Turn is. I'm talking about 10 minutes after departure at 7k feet
> where the departure airport, if you can make it, is the best landing option.
> Then for all intents and purposes its a 180 degree turn.
>

Absolutely. As long as you have continued climbing at a higher rate
than the descent will be.

About 2 years ago I got to practice this. On an early morning
takeoff for a 300 mile cross-country flight, the OAT was cool and the
plane was light, so I climbed out at 900 ft./min. to reach my cruising
altitude quickly. At around 9K ft. the engine got real loud and I
realized I had broken something in the exhaust. I shut down the
engine so as not to catch the cowl on fire. I was 6 miles away from
the airport and knew I had climbed at much better than the 750 ft./min
descent rate, so the return glide was really a no-stress event. When
I got back to the pattern, I actually had about 1K ft. too much
altitude and had to circle to lose it before deadsticking on to the
same runway I had departed.

John Galban=====>N4BQ (PA28-180)

[JerryK]

"Harold" > wrote in message
...
> Well obviously, but I'm not talking about in the pattern area like the
> Impossible Turn is. I'm talking about 10 minutes after departure at 7k
feet
> where the departure airport, if you can make it, is the best landing
option.
> Then for all intents and purposes its a 180 degree turn.
>

In that case you might want to use ft/nm as a better measurement.

jerry

[Jack Herer]

"Harold" > wrote in message >...
> If a small single engine plane can out-climb its engine-out glide ratio from
> take off through the top of climb point, wouldn't it follow that it can
> always theoretically make it back to the departure airport in the event of
> engine failure ? Assuming straight out departure, no wind, and the altitude
> loss in the 180 turnback is offset by the runway portion you didn't use. If
> my best glide is 85 KTAS and it loses 700 fpm at that speed, shouldn't I be
> guaranteed I can make it back if I climb at 84 KTAS and 701 fpm ?

I have a close friend who was an experienced pilot (IFR rating - 6
years of flying - owned his own plane) and had engine failure on
takeoff and did not make it back to the airport. He was practicing a
short field take off which probably didn't help the situation but
impacted terrain about 1/4 mile short of the runway (he hit power
lines that were right next to this airport). Anyway, he died of
injuries from the crash. The wing sheared during the impact dumping
fuel into the cockpit and started a bad fire but fortunately death
occurred upon impact.

Reports placed him at about 700 ft of altitude when engine failure
occurred but it could have been lower than this value.

[David Megginson]

Martin Hotze > writes:

> My examiner showed me at the ppl exam some 180 degree turns with a
> C172 at climb-out speed and he lost less than 100ft altitude.

A standard-rate 180-degree turn takes one minute, so even ignoring the
higher wing loading in the turn, a power-off descent rate of less than
100 fpm doesn't make sense for a 172. Which climb-out speed was he
using, Vx, Vy, or enroute climb? If he had enough extra speed, he
could have traded some of it for altitude, but that runs out pretty
fast.


All the best,


David

[Jeff Franks]

There was a good article in Plane & Pilot (i think) a few months back about
making your mind up about these kinds of problems well before you need them.
Especially if your flying from your "home" strip, you should already know
where you'd put it down if you lost the engine and you already have the
go/no go altitude in your brain before you depart. If your below your limit
when the engine quits, you don't second guess yourself, you just push over
to best glide and land straight ahead (or as close to it as possible).

It also mentioned that you should consciously fight the urge to save the
plane or "get back to the runway". The kneejerk reaction is to think that
if we can just get back to there, then everything will be ok.


>
> I have a close friend who was an experienced pilot (IFR rating - 6
> years of flying - owned his own plane) and had engine failure on
> takeoff and did not make it back to the airport. He was practicing a
> short field take off which probably didn't help the situation but
> impacted terrain about 1/4 mile short of the runway (he hit power
> lines that were right next to this airport). Anyway, he died of
> injuries from the crash. The wing sheared during the impact dumping
> fuel into the cockpit and started a bad fire but fortunately death
> occurred upon impact.
>
> Reports placed him at about 700 ft of altitude when engine failure
> occurred but it could have been lower than this value.

[Mike Rapoport]

Then he lost a lot of airspeed.

Mike
MU-2

"Martin Hotze" > wrote in message
...
> "Mike Rapoport" > wrote:
>
> > Not unless you are planning to glide straight ahead. You will lose a
lot of
> > altitude in the turn.
>
>
> My examiner showed me at the ppl exam some 180 degree turns with a C172
> at climb-out speed and he lost less than 100ft altitude.
>
> #m
> --
> http://www.crunchweb.net/87billion/

[David Megginson]

Martin Hotze > writes:

>> higher wing loading in the turn, a power-off descent rate of less than
>> 100 fpm doesn't make sense for a 172. Which climb-out speed was he
>> using, Vx, Vy, or enroute climb? If he had enough extra speed, he
>> could have traded some of it for altitude, but that runs out pretty
>> fast.
>
> well it worked. and I survived :-)

How about details? What was the entry airspeed and exit airspeed, and
how did he make the turn?


All the best,


David

[JerryK]

In the sim at Flight Safety, we did these type of turn at 45-60 degrees.


"David Megginson" > wrote in message
...
> Martin Hotze > writes:
>
> >> higher wing loading in the turn, a power-off descent rate of less than
> >> 100 fpm doesn't make sense for a 172. Which climb-out speed was he
> >> using, Vx, Vy, or enroute climb? If he had enough extra speed, he
> >> could have traded some of it for altitude, but that runs out pretty
> >> fast.
> >
> > well it worked. and I survived :-)
>
> How about details? What was the entry airspeed and exit airspeed, and
> how did he make the turn?
>
>
> All the best,
>
>
> David