Why do some modern glider wings like the Schleicher 29 have a tadpole shape rather than a teardrop shape?Why...
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Why do some modern glider wings like the Schleicher 29 have a tadpole shape rather than a teardrop shape?
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Why do some modern glider wings like the Schleicher 29 have a tadpole shape rather than a teardrop shape?
Why and when to use flaps?Do negative flaps increase glide ratio?Why do some light sport aircraft have clipped wings?What are the vertical pieces of metal on the Slingsby Swallow wing for?Why are modern aircraft wings often pointed instead being more rectangular?Regarding the 1902 Wright glider. Why is the airspeed, Va, calculated adding the ground speed, Vg, and wind speed, Vw?Why did the DC-3 have wing sweep?What aerodynamic characteristics arise from trailing edge sweep angle?What are the benefits of using thick trailing edge flaps?If both propellers and wings are airfoils, then why do propellers deflect air perpendicularly to the rotor, but wings not?Why does the A320’s maximum allowable aileron deflection decrease, rather than increase, when the flaps are extended?
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Why do some modern glider wings have a tadpole shape rather than a teardrop shape, like the schleicher 29? or did they just add a flat plate at the trailing edge for flaps and ailerons?
see pic
aerodynamics
asked 9 hours ago
FredFred
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Why do some modern glider wings have a tadpole shape rather than a teardrop shape, like the schleicher 29? or did they just add a flat plate at the trailing edge for flaps and ailerons?
see pic
aerodynamics
asked 9 hours ago
FredFred
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add a comment
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$begingroup$
Why do some modern glider wings have a tadpole shape rather than a teardrop shape, like the schleicher 29? or did they just add a flat plate at the trailing edge for flaps and ailerons?
see pic
aerodynamics
asked 9 hours ago
FredFred
6012 silver badges10 bronze badges
$endgroup$
Why do some modern glider wings have a tadpole shape rather than a teardrop shape, like the schleicher 29? or did they just add a flat plate at the trailing edge for flaps and ailerons?
see pic
aerodynamics
aerodynamics
asked 9 hours ago
FredFred
6012 silver badges10 bronze badges
asked 9 hours ago
FredFred
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asked 9 hours ago
FredFred
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asked 9 hours ago
FredFred
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3 Answers
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The flaps and ailerons are "reflexed" on this glider. They have been raised to a setting above the normal zero position, above the airfoil's normal chord line. A number of flapped gliders have this feature.
Two main benefits are a reduction in pitching moment as the pressure distribution on the wing is moved forward, so less downforce work for the tail, reducing trim drag, and lower induced drag because with the trailing edge partially unloaded it has an effect like reducing wing area and moves the best L/D speed up a bit. So overall, best glide angle is a bit better, and the speed it's achieved is a bit higher.
You use reflex for "penetration", going as flat as possible as fast as possible, for whatever reason, like getting through an area of sink in a hurry.
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
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do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
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Flapped airfoils will have a suction peak once the flap is deflected away from its zero deflection position. This means more load on the boundary layer and earlier flow separation at the same lift coefficient. In order to avoid this suction peak over a range of flap angles, the airfoil contour is optimized on the top side for a small positive deflection and on the lower side for a small negative deflection. Now you get that "tadpole" shape between those two flap deflections, but also more flap effectivity and lower drag.
This effect is increased on the upper side for negative flap deflections. They are standard on gliders in order to shift the laminar bucket of the airfoil to the actual lift coefficient. I bet the lower side contour of the wing in the photo is smooth across the flap hinge line.
answered 8 hours ago
Peter KämpfPeter Kämpf
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You can position the flaps/ailerons on the ASG 29 not only downwards but also upwards. The flap/aileron is triangle shaped as you can (barely) see on this photo of an ASG 29 wing joint:
Basically you can reduce the lift (and therefore drag) of the wing by moving the flaps/ailerons upwards, extracting better speed from the wing.
answered 8 hours ago
ChrisChris
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3 Answers
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active
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votes
3 Answers
3
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oldest
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active
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$begingroup$
The flaps and ailerons are "reflexed" on this glider. They have been raised to a setting above the normal zero position, above the airfoil's normal chord line. A number of flapped gliders have this feature.
Two main benefits are a reduction in pitching moment as the pressure distribution on the wing is moved forward, so less downforce work for the tail, reducing trim drag, and lower induced drag because with the trailing edge partially unloaded it has an effect like reducing wing area and moves the best L/D speed up a bit. So overall, best glide angle is a bit better, and the speed it's achieved is a bit higher.
You use reflex for "penetration", going as flat as possible as fast as possible, for whatever reason, like getting through an area of sink in a hurry.
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
$endgroup$
$begingroup$
do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
add a comment
|
$begingroup$
The flaps and ailerons are "reflexed" on this glider. They have been raised to a setting above the normal zero position, above the airfoil's normal chord line. A number of flapped gliders have this feature.
Two main benefits are a reduction in pitching moment as the pressure distribution on the wing is moved forward, so less downforce work for the tail, reducing trim drag, and lower induced drag because with the trailing edge partially unloaded it has an effect like reducing wing area and moves the best L/D speed up a bit. So overall, best glide angle is a bit better, and the speed it's achieved is a bit higher.
You use reflex for "penetration", going as flat as possible as fast as possible, for whatever reason, like getting through an area of sink in a hurry.
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
$endgroup$
$begingroup$
do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
add a comment
|
$begingroup$
The flaps and ailerons are "reflexed" on this glider. They have been raised to a setting above the normal zero position, above the airfoil's normal chord line. A number of flapped gliders have this feature.
Two main benefits are a reduction in pitching moment as the pressure distribution on the wing is moved forward, so less downforce work for the tail, reducing trim drag, and lower induced drag because with the trailing edge partially unloaded it has an effect like reducing wing area and moves the best L/D speed up a bit. So overall, best glide angle is a bit better, and the speed it's achieved is a bit higher.
You use reflex for "penetration", going as flat as possible as fast as possible, for whatever reason, like getting through an area of sink in a hurry.
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
$endgroup$
The flaps and ailerons are "reflexed" on this glider. They have been raised to a setting above the normal zero position, above the airfoil's normal chord line. A number of flapped gliders have this feature.
Two main benefits are a reduction in pitching moment as the pressure distribution on the wing is moved forward, so less downforce work for the tail, reducing trim drag, and lower induced drag because with the trailing edge partially unloaded it has an effect like reducing wing area and moves the best L/D speed up a bit. So overall, best glide angle is a bit better, and the speed it's achieved is a bit higher.
You use reflex for "penetration", going as flat as possible as fast as possible, for whatever reason, like getting through an area of sink in a hurry.
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
answered 9 hours ago
John KJohn K
42.3k1 gold badge78 silver badges145 bronze badges
42.3k1 gold badge78 silver badges145 bronze badges
$begingroup$
do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
add a comment
|
$begingroup$
do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
$begingroup$
do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
do airliners use this "reflexing" technique? It seems their upper airfoil shape has been greatly flattened for high speed cruise efficiency.
$endgroup$
– Robert DiGiovanni
8 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
$begingroup$
I've never seen that but it's an interesting point because airliners cruise at low indicated airspeed relatively close to max L/D. Likely it's simply not practical to make a double slotted fowler flap system typical of airliners reflex up. You only see it on simple plain flaps.
$endgroup$
– John K
6 hours ago
add a comment
|
$begingroup$
Flapped airfoils will have a suction peak once the flap is deflected away from its zero deflection position. This means more load on the boundary layer and earlier flow separation at the same lift coefficient. In order to avoid this suction peak over a range of flap angles, the airfoil contour is optimized on the top side for a small positive deflection and on the lower side for a small negative deflection. Now you get that "tadpole" shape between those two flap deflections, but also more flap effectivity and lower drag.
This effect is increased on the upper side for negative flap deflections. They are standard on gliders in order to shift the laminar bucket of the airfoil to the actual lift coefficient. I bet the lower side contour of the wing in the photo is smooth across the flap hinge line.
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
$endgroup$
add a comment
|
$begingroup$
Flapped airfoils will have a suction peak once the flap is deflected away from its zero deflection position. This means more load on the boundary layer and earlier flow separation at the same lift coefficient. In order to avoid this suction peak over a range of flap angles, the airfoil contour is optimized on the top side for a small positive deflection and on the lower side for a small negative deflection. Now you get that "tadpole" shape between those two flap deflections, but also more flap effectivity and lower drag.
This effect is increased on the upper side for negative flap deflections. They are standard on gliders in order to shift the laminar bucket of the airfoil to the actual lift coefficient. I bet the lower side contour of the wing in the photo is smooth across the flap hinge line.
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
$endgroup$
add a comment
|
$begingroup$
Flapped airfoils will have a suction peak once the flap is deflected away from its zero deflection position. This means more load on the boundary layer and earlier flow separation at the same lift coefficient. In order to avoid this suction peak over a range of flap angles, the airfoil contour is optimized on the top side for a small positive deflection and on the lower side for a small negative deflection. Now you get that "tadpole" shape between those two flap deflections, but also more flap effectivity and lower drag.
This effect is increased on the upper side for negative flap deflections. They are standard on gliders in order to shift the laminar bucket of the airfoil to the actual lift coefficient. I bet the lower side contour of the wing in the photo is smooth across the flap hinge line.
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
$endgroup$
Flapped airfoils will have a suction peak once the flap is deflected away from its zero deflection position. This means more load on the boundary layer and earlier flow separation at the same lift coefficient. In order to avoid this suction peak over a range of flap angles, the airfoil contour is optimized on the top side for a small positive deflection and on the lower side for a small negative deflection. Now you get that "tadpole" shape between those two flap deflections, but also more flap effectivity and lower drag.
This effect is increased on the upper side for negative flap deflections. They are standard on gliders in order to shift the laminar bucket of the airfoil to the actual lift coefficient. I bet the lower side contour of the wing in the photo is smooth across the flap hinge line.
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
edited 5 hours ago
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
answered 8 hours ago
Peter KämpfPeter Kämpf
172k14 gold badges438 silver badges702 bronze badges
172k14 gold badges438 silver badges702 bronze badges
add a comment
|
add a comment
|
$begingroup$
You can position the flaps/ailerons on the ASG 29 not only downwards but also upwards. The flap/aileron is triangle shaped as you can (barely) see on this photo of an ASG 29 wing joint:
Basically you can reduce the lift (and therefore drag) of the wing by moving the flaps/ailerons upwards, extracting better speed from the wing.
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
$endgroup$
add a comment
|
$begingroup$
You can position the flaps/ailerons on the ASG 29 not only downwards but also upwards. The flap/aileron is triangle shaped as you can (barely) see on this photo of an ASG 29 wing joint:
Basically you can reduce the lift (and therefore drag) of the wing by moving the flaps/ailerons upwards, extracting better speed from the wing.
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
$endgroup$
add a comment
|
$begingroup$
You can position the flaps/ailerons on the ASG 29 not only downwards but also upwards. The flap/aileron is triangle shaped as you can (barely) see on this photo of an ASG 29 wing joint:
Basically you can reduce the lift (and therefore drag) of the wing by moving the flaps/ailerons upwards, extracting better speed from the wing.
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
$endgroup$
You can position the flaps/ailerons on the ASG 29 not only downwards but also upwards. The flap/aileron is triangle shaped as you can (barely) see on this photo of an ASG 29 wing joint:
Basically you can reduce the lift (and therefore drag) of the wing by moving the flaps/ailerons upwards, extracting better speed from the wing.
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
answered 8 hours ago
ChrisChris
1,4105 silver badges14 bronze badges
1,4105 silver badges14 bronze badges
add a comment
|
add a comment
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