leading edge flaps

"Arquebus257WeaMag" wrote...
This questions has been killing me, what is the name of the leading
edge flaps that you find on airliners for example. Ive heard the name
slats, but I know there is another name for it.

In general, they can be called "leading edge flaps."

Some of them are specific designs, such as the "Kreuger flaps" on 727s and the
inboard segment of 747s. Others, such as the outboard segments of the 747s,
look like, and perform the same function when extended, as the "leading edge
slats" on the F-86, A-4, and A-6. However, because of the manner in which they
are stowed and deployed on the 747, they are still called "leading edge flaps."

Flaps and slats increase the wing camber which produces obvious advantages.
Extensible flaps and slats increase the wing area which produces obvious
advantages.

The slat (not to be confused with the leading edge flap) energizes the upper
surface boundary layer, thus delaying upper surface flow separation and stall.
This effect increases the stall angle-of-attack, increases directional
stability, but sometimes increases or decreases the coefficient of lift,
depending on the wing system design.

The net effect of both slat and flap extension working in unison is to increase
lift, increase stall angle-of-attack, and increase directional stability. This
serves to reduce the landing speed. It also serves to increase aircraft "G"
(normal acceleration) above the clean wing value at a given airspeed.




Kurt Todoroff


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Consent, not compulsion.

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"Kurt R. Todoroff" wrote in message
...
Flaps and slats increase the wing camber which produces obvious
advantages.
Extensible flaps and slats increase the wing area which produces obvious
advantages.

The slat (not to be confused with the leading edge flap) energizes the
upper
surface boundary layer, thus delaying upper surface flow separation and
stall.
This effect increases the stall angle-of-attack, increases directional
stability, but sometimes increases or decreases the coefficient of lift,
depending on the wing system design.

The net effect of both slat and flap extension working in unison is to
increase
lift, increase stall angle-of-attack, and increase directional stability.
This
serves to reduce the landing speed. It also serves to increase aircraft
"G"
(normal acceleration) above the clean wing value at a given airspeed.

Very nice, Kurt.

Of all the lift devices the Krueger flap is in my opinion the oddest
one. Its hinged at the front and pivots forward into 'lift' position.
Stick out your hand, palm down, fingers folded back flat. Now
straighten your hand so that your fingers are bent down about 30
degrees from the plane of your palm. You have imitated a Kruger flap.
FWIW the L1011 had a neat mode of spoiler operation - with the
trailing edge flaps in land (33 degrees) position the wing spoilers
were positioned up 8 degrees. Slight movement of the yoke fore or aft
from the trimmed position raised or lowered the spoilers effecting a
useful change in lift with minimal change in AOA. Made it very easy to
stay on a glideslope or maintain a set rate of descent.
Walt BJ

"WaltBJ" wrote in message
om...
Of all the lift devices the Krueger flap is in my opinion the oddest
one. Its hinged at the front and pivots forward into 'lift' position.
Stick out your hand, palm down, fingers folded back flat. Now
straighten your hand so that your fingers are bent down about 30
degrees from the plane of your palm. You have imitated a Kruger flap.
FWIW the L1011 had a neat mode of spoiler operation - with the
trailing edge flaps in land (33 degrees) position the wing spoilers
were positioned up 8 degrees. Slight movement of the yoke fore or aft
from the trimmed position raised or lowered the spoilers effecting a
useful change in lift with minimal change in AOA. Made it very easy to
stay on a glideslope or maintain a set rate of descent.

The L-1011 lives on as a launch platform and offers performance superior in
both rate of climb and payload, over the B-52.

"WaltBJ" wrote...
FWIW the L1011 had a neat mode of spoiler operation - with the
trailing edge flaps in land (33 degrees) position the wing spoilers
were positioned up 8 degrees. Slight movement of the yoke fore or aft
from the trimmed position raised or lowered the spoilers effecting a
useful change in lift with minimal change in AOA. Made it very easy to
stay on a glideslope or maintain a set rate of descent.

Also done in the Navy F-14 and S-3, with minor variations.

Also done in many gliders, though manually, as a matter of course in the landing
pattern...

"John R Weiss" wrote:
"WaltBJ" wrote:

FWIW the L1011 had a neat mode of spoiler operation - with the
trailing edge flaps in land (33 degrees) position the wing spoilers
were positioned up 8 degrees. Slight movement of the yoke fore or aft
from the trimmed position raised or lowered the spoilers effecting a
useful change in lift with minimal change in AOA. Made it very easy to
stay on a glideslope or maintain a set rate of descent.

Also done in the Navy F-14 and S-3, with minor variations.

Also done in many gliders, though manually, as a matter of course in the landing
pattern...

In gliders, I raise the spoilers (about halfway) while still on
downwind and leave them partially up (occassionally raising 'em
all the way if needed) all the way down to the flare.

Another commonly used method to stay on the glideslope or maintain
a set rate of descent that hasn't been mentioned is via prop pitch
(e.g: decrease pitch if drifting above glideslope, increase pitch if
drifting below glideslope).