Flaps on take-off and landing

Johnson Bar


You can also use the flaps to "jump over" a fence or ditch
that you see at the last moment before a forced landing if
they are up for the glide.

But the flaps move the center of lift aft on the wing and
you need back elevator pressure to force the main gear
(trike) or tailwheel on the ground to prevent weather vaning
and skidding the wheels under braking. The flaps will tend
to lift the lift the tail and you need to follow through on
the flare to lever the balance point on the main gear.

A tailwheel airplane will use some forward elevator for a
wheel landing, but when the tail comes down [or is lowered]
you still need the stick full aft. Of course during taxi
you must use the ailerons and elevator to control for cross
and tailwinds.


"Cubdriver" usenet AT danford.net wrote in message
...
| On Thu, 14 Sep 2006 07:55:05 +0200, Mxsmanic

| wrote:
|
| Similarly, I retract the
| flaps completely as soon as I'm completely on the runway
for landing,
| so that the wind doesn't push me around. Is this the
correct way to
| do it?
|
| The first plane with flaps that I flew was a PA-18 Super
Cub. When I
| reached for the flap lever (it has a name, but I forget),
what I got
| was a rocket from my instructor in the back seat. "Don't
touch
| anything till you stop rolling!" Of course the PA-18 is a
taildragger
| and more sensitive to a pilot's inattention.
|
| A year later I took Damian Delgaizo's bush-flying course
in Andover
| NJ. The plane was an Aviat Husky with a similar flap
lever, and we
| made much greater use of it. The splendid trick was to fly
over a
| cornfield (whatever) in ground effect, then dump the flaps
as soon as
| the mains crossed the threshold of the (grass) field, so
that the
| Husky stopped within 250 feet.
|

Jim Macklin wrote:
...
You can also use the flaps to "jump over" a fence or ditch
that you see at the last moment before a forced landing if
they are up for the glide.
...
Yes and that's one lesson I'll never forget. The instructor had me do a
power-off "short approach" and told me I was *not* allowed to apply
power no matter how bad I thought it was! The pucker factor increased
enormously and I could see the edge of the hill under the runway
looming. Certain that we were going to crash into it, I was begging to
add power. The instructor calmly demonstrated how to use flaps just to
get a few more feet and complete the landing. It was a good lesson but
I think he owes me some new underwear.

Stubby wrote
The instructor calmly demonstrated how to use flaps just to
get a few more feet and complete the landing. It was a good
lesson but I think he owes me some new underwear.

Best glide distance with flaps is always less that best glide
distance flaps up. Bad demonstration...bad lesson learned.
The reason that most GA airplanes use flaps is to increase
drag and steepen the glide angle without increasing the speed.

Bob Moore

Gliding with the flaps up and about 5 knots faster than
"best glide" allows the pilot to "stretch" the glide by a
slight increase in pitch attitude bringing the speed to the
best glide speed. If you fly at best glide you have no
option to stretch the glide since any increase of decrease
in speed will steepen the glide.

Also, if there is any wind, you want minimum sink if flying
downwind and you need a faster speed when flying into the
wind. Extreme example, wind 50 knots, airspeed 50 knots,
flight path vertical with no forward progress.

Flap extension reduces the stalling speed, often only a few
knots, but lift increases as does drag. The airplane will
balloon and slow very fast, the extra distance and altitude
gained is only a few feet, but if all you need is to clear a
5 foot cattle fence or a 10 foot wide ditch, that is a
technique that is useful.


--
James H. Macklin
ATP,CFI,A&P

"Bob Moore" wrote in message
. 122...
| Stubby wrote
| The instructor calmly demonstrated how to use flaps just
to
| get a few more feet and complete the landing. It was a
good
| lesson but I think he owes me some new underwear.
|
| Best glide distance with flaps is always less that best
glide
| distance flaps up. Bad demonstration...bad lesson learned.
| The reason that most GA airplanes use flaps is to increase
| drag and steepen the glide angle without increasing the
speed.
|
| Bob Moore

Jim Macklin wrote
Flap extension reduces the stalling speed, often only a few
knots, but lift increases as does drag. The airplane will
balloon and slow very fast, the extra distance and altitude
gained is only a few feet, but if all you need is to clear a
5 foot cattle fence or a 10 foot wide ditch, that is a
technique that is useful.

Can't create energy out of thin air Jim. You would clear the
same 5 foot fence just by increasing the angle of attack and
in both cases, glide a shorter distance if you were at best
L/D to start with.

Bob Moore

Flap extension does cause an immediate (manual flaps)
increase in lift, rotating the aircraft also increases lift
but the flaps seem to work better in the case of just
"jumping" a few feet because they also lower the stall speed
giving a slightly greater margin at the same energy level.



"Bob Moore" wrote in message
. 122...
| Jim Macklin wrote
| Flap extension reduces the stalling speed, often only a
few
| knots, but lift increases as does drag. The airplane
will
| balloon and slow very fast, the extra distance and
altitude
| gained is only a few feet, but if all you need is to
clear a
| 5 foot cattle fence or a 10 foot wide ditch, that is a
| technique that is useful.
|
| Can't create energy out of thin air Jim. You would clear
the
| same 5 foot fence just by increasing the angle of attack
and
| in both cases, glide a shorter distance if you were at
best
| L/D to start with.
|
| Bob Moore

Nope.

As long as you are flying in the green arc, the wing alone will ALWAYS give
you better lift.


Karl
"Curator" N185KG
screw bottom feeders


"Jim Macklin" wrote in message
news:2njOg.22663$SZ3.21477@dukeread04...
Flap extension does cause an immediate (manual flaps)
increase in lift, rotating the aircraft also increases lift
but the flaps seem to work better in the case of just
"jumping" a few feet because they also lower the stall speed
giving a slightly greater margin at the same energy level.

A friend of mine was a pilot for the State of Illinois.
They were flying the governor to Washington, DC in the King
Air [about 20 years ago]. Somewhere near Cleveland [I
think] they saw a flicker and then had a DC 9 at their
altitude pass right to left a few hundred feet in front.
Turned out the sector controller had forgotten to issue the
higher altitude to the DC 9. The Governor did get a
personal phone call from the Sec DOT ad the Admin at the FAA
with an apology.

The form the pilot filled out had this question, "What the
PICs first action after the near mid-air?"

The pilot wrote down, "Changed shorts"




"Stubby" wrote in
message . ..
|
|
| Jim Macklin wrote:
| ...
| You can also use the flaps to "jump over" a fence or
ditch
| that you see at the last moment before a forced landing
if
| they are up for the glide.
| ...
| Yes and that's one lesson I'll never forget. The
instructor had me do a
| power-off "short approach" and told me I was *not* allowed
to apply
| power no matter how bad I thought it was! The pucker
factor increased
| enormously and I could see the edge of the hill under the
runway
| looming. Certain that we were going to crash into it, I
was begging to
| add power. The instructor calmly demonstrated how to use
flaps just to
| get a few more feet and complete the landing. It was a
good lesson but
| I think he owes me some new underwear.

Stubby wrote:


Jim Macklin wrote:
...

You can also use the flaps to "jump over" a fence or ditch that you
see at the last moment before a forced landing if they are up for the
glide.

...
Yes and that's one lesson I'll never forget. The instructor had me do a
power-off "short approach" and told me I was *not* allowed to apply
power no matter how bad I thought it was! The pucker factor increased
enormously and I could see the edge of the hill under the runway
looming. Certain that we were going to crash into it, I was begging to
add power. The instructor calmly demonstrated how to use flaps just to
get a few more feet and complete the landing. It was a good lesson but
I think he owes me some new underwear.
That is why I like to plan just a little high and slip the last couple
of feet for the runway. During my commerical check ride I was coming up
a little short on a similated engine out and pointed the nose down to
gain airspeed. Work just find and landed right on the numbers. The
examiner said that was great. I passed the check ride.

--

Regards, Ross
C-172F 180HP
KSWI

Ross Richardson wrote:

During my commerical check ride I was coming up
a little short on a similated engine out and pointed the nose down to
gain airspeed. Work just find and landed right on the numbers.

I'm guessing that you were below best glide speed at the time?