Flaps on take-off and landing

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.

Try it. It is not a long term effect, just a quick change
to get over the short fence or narrow ditch.


"karl gruber" wrote in message
...
| 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.
|
|
|

"Jim Macklin" writes:

Try it. It is not a long term effect, just a quick change
to get over the short fence or narrow ditch.

So it's like ground effect, right?

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Fri, 15 Sep 2006 16:49:12 +0200, Mxsmanic
wrote in :

So it's like ground effect, right?

No. It's like increasing the angle of attack on a thicker wing
section which stalls at a lower speed.

Ground effect is completely different:

http://en.wikipedia.org/wiki/Ground_effect
The term Ground effect (or Wing In Ground effect) refers to the
increase in lift experienced by an aircraft as it approaches
within roughly 1/4 of a wingpspan's length of the ground or other
level surface (such as the sea)

http://www.avweb.com/news/airman/185905-1.html