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40

Why no flaps? Flaps change the pitching moment of a wing. After all, they add lift over the full chord, so the sum of the increased lift attacks at about mid-chord, which is a quarter chord aft of the regular lift. If there is no separate tail surface to compensate for the pitching moment caused by that extra lift, the aircraft will quickly pitch nose-down ...

14

Assuming maximum altitude for the highest blimp is 74,000 feet, and the rail to be angled at 15 degrees, it gives us a rail length of 285,000 feet. The HiSentinel stratospheric airship flew that high, and was able to carry only 36 kg. The steel rail/rope would weigh roughly 5.5 million kg. Based on steel density and a good sized rope, to withstand the ...

13

Technically, F-16 and "similar fighters" have leading edge flaps (LEF) (or droop flaps), rather than slats. The difference is that they don't form a gap between themselves and the main surface when deflected. This makes them usable at high speeds, whereas slats are typically used for low-speed takeoff/landing. For fighters, the most important use ...

12

The idea is to generate a vortex near the fuselage. In most cases we do not want any vortexes, as the unnecessary air movement always causes an increase in drag. In this case however, you need them. As the air flow separates from this small triangle wing while at large angles of attack, it gains a rotary motion (if you look at the left wing standing in ...

11

Similar to a leading edge flap, fixed in the extended position with no gaps: The nose is lowered, so at high angles of attack the flow still has its stagnation point at the round nose where on an un-drooped nose it would had slipped below the nose section. This reduces the suction peak near the nose of the upper surface pressure distribution and ...

11

Normally, one degree of flaps in fact only translates to an extension of the leading edge devices (e.g. slats), trailing edge flaps remain fully retracted. On some aircraft this configuration can be used for take-off. Combination of flaps and spoiler is for example used in slow flight on steep descends. The flaps ensure that the wing doesn't stall, the ...

10

The area, or as originally written, length and width*, are but two of many parameters that define the flaps and slats. The final parameters are a result of an iterative process, as shown above. You try a set of parameters, if they don't work, you go back one step, or even two steps (redesigning the wing). For example when the A320 was stretched to become ...

10

This might be a bit late but the short answer is, again, no. Check NACA report 427 and Experimental investigation of a Handley Page 44f wing. Slots at locations other than the vicinity of the leading edge are shown to be rather useless. In addition, there seems to be no correlation between the "rounding" of the channel inlet and a better performance. The ...

9

Unless something broke mid-flight -- which you would have probably been told about as a passenger because of the faster landing speed -- leading edge devices (slats) are used for takeoff, approach, and landing on the A320-family. For takeoff the slats are put in position 18 or 22, and for landing in position 22 or 27, as the table below from an A320-family ...

9

@DamalaniSingh: I wonder why you see the need for a bounty when web pages such as this give a good explanation already. In order to avoid a link-only answer, I will summarize the LEX-related gist here (LEX = leading edge extension). You may know that a delta wing forms a powerful vortex on its suction side at high angle of attack which allows it to work ...

8

No, it will not work in the way you plotted it. First, the corners of the duct should be nicely rounded. With the sharp corners you will get a lot of vorticity, but little lift increase. Actually, lift will drop and drag will go up. Next, a gap works best when connected with a contour break, such as that of a slat or a flap. If you round the corners and ...

8

According to a F16 forum.. Those are the LEF's (leading edge flaps). They are there to produce extra lift to the wings during high AOA and low airspeeds. The reason they are up on the ground is they are wired to the left and right main WOW (weight on wheels) switches. They are schedule to -2 degrees on the ground. The only time they move on the ground is ...

7

It works but your description is not so clear about the real size of the gap. Gliders sometimes have little holes along the wing on the upper side where air from beneath is provided to them by a little duct. The reason is to keep the linear air flow straight a little longer at low speeds. I have not found a live picture. For this I'll have to visit the ...

7

Leading edge extensions like slats are used in airliners. Most of these are controlled ones, so as to improve low speed characteristics. By Adrian Pingstone (Arpingstone) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4761104 The dog tooth extensions were used in some older airliners like the Ilyushin Il-62 and the Vickers ...

6

The strakes function as giant vortex generators. They generate vortices at high AOAs to improve airflow over the rudder at low speeds. During the Q400 test program it was found that there was some local flow separation at the lower area of the rudder (reducing rudder power and possibly creating unpleasant vibration) and this is a classic, relatively hassle-...

6

Yes leading edge devices indeed postpone stall to a higher Angle of Attack. They are particularly useful for: Airfoils which are prone to leading edge stall. Deflection of the trailing edge flap creates upwash at the wing nose, which reduces stall AoA mainly on thinner wing profiles. Aeroplanes which use lift dumpers as speed brakes. Deflection of the ...

6

In modern gliders, active tripping of the laminar boundary layer helps to reduce or avoid a laminar separation bubble. There are three ways of doing this: Noppenband (dimple tape): Close-up picture of a spool of Noppenband (picture source) Zig-Zag-tape: Spool of zig-zag tape (picture source) Blowhole tripping: a line of tiny holes (0.8 mm diameter, ...

5

The beauty of the pure delta configuration was you could get a reasonably low supersonic drag configuration in a planform with a lot of wing area, essential for really high altitude cruise and for reasonable landing speeds without high lift devices. It was a good overall compromise for Concorde's mission. The Avro Arrow, produced then scrapped in Canada ...

5

Most modern airliners have some form or other of mechanism that does exactly that, mostly for the slats (which are more important in stall prevention, anyway). E.g. on modern Airbusses, there is a Slat Alpha Lock function which prevents slat retraction at high angles of attack, on the Boeings there is a Slat Auto-Gap function extending slats from mid to ...

5

Finally! The Vought OS2U Kingfisher (first flight 1938). At least the OS2U-2 model... Production variant with minor equipment changes and powered by a 450 hp (336 kW) Pratt & Whitney R-985-50, 158 built. [emphasis mine] ... had default Maxwell slots, thanks to a wartime NACA report.[1] The report makes no mention of the plane's model, but another ...

5

Slats increase the stall angle, flaps do not, that is the key issue - safety margin. Plus on aeroplanes with high wing loading even triple slotted fowler flaps may not cut the mustard, slats are simply required additionally. Pic from this answer, showing that the stall AoA actually decreases in this example. The second pic in the referenced answer shows the ...

5

Slats are a necessity when the wing uses slotted flaps or Fowler flaps for maximum lift. Those flaps cannot reach over the whole span of the wing to leave room near the wingtips for ailerons. Once the flaps are extended, they increase the incidence of the wing along the flap span. This leaves the outer wing at a lower incidence, but in the vortex field of ...

4

Definitely use the local Reynolds number on each of the flaps! The flap will only work properly if it is allowed to produce its own, fresh boundary layer. If instead it inherits the slow, thick boundary layer of the wing or flap ahead of it, the flow would soon separate and the flap would loose most of its effectiveness. Note that a Reynolds number is ...

4

Because with a delta wing the trailing edge has the elevators and it's too far aft to have a flap. They depend on wing area and the ability to operate at much higher AOAs than straight wings to get the speeds down. As for slats, they don't increase Clmax all that much, only a little bit from the increase in chord in drooping the leading edge. The main ...

4

It did not need them. Concorde could operate from most commercial airports and did not need especially long runways. Retractable canards add drag and the mechanism is a point of failure. I fail to see how Tu-144 canards is a “superior” feature as they were added to support a less effective wing. Very much related: Why is the Tu-144 the only commercial ...

4

The aspect ratio of a wing is defined as: $$\text{AR} \equiv \frac{s^2}{A} ,$$ where $s$ is the wingspan and $A$ is the total wing area. Some types of flaps are not only increasing wing camber, but also the wing area: The Fowler, Fairey-Youngman and Gouge types of flap increase the wing area in addition to changing the camber. (Wikipedia) Since the ...

4

Neither the Dash 8 nor ATR families (which cover the bulk of regional TP market) do. Your last two sentence pretty much summarizes it. Some of the additional lift potential of a slatted wing is from the camber increase when the slat is extended, but most is from the ability of the wing to operate well beyond the normal stalling AOA of around 15-16 degrees, ...

3

The suction peak is the point of lowest pressure on an airfoil, in other words the highest point on a typical pressure or Cp graph of an airfoil. On an airfoil it's typically located just after the leading edge on the upper surface, take a look at this image for instance. In that image you can also see that as you increase the angle of attack of the ...

3

I can answer on the F-16 :) The general system description tells us that the Leading Edge Flaps may be positioned from 2 degrees (1 inch) up to 25 degrees (12-1/2 inches) down. I assume it is similar on the F-22 and F-35, since the Leading Edge Flap subsystem provides high lift for takeoff and landing and optimizes performance in each flight phase.

2

A basic problem you have with this design is weather - what do you do when a storm passes through? Due to their large surface area, your blimps at lower altitudes are going to be pushed around a lot by high winds, probably to destruction. Storms, and the associated high winds, can extend upwards of 40k feet, in extreme cases. You might think about ...

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