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Wikipedia says that the F-8 was to have

a landing speed of no more than 100 mph (160 km/h)

This web page says that the F-8 did have

Stalling speed 157 mph.

The two don't explicitly discuss exactly the same thing, but I do note that e.g. the quoted cruise speed of 570 mph agrees on both. Unfortunately, neither page seems to specify the actual landing speed of the final aircraft.

From an aerodynamics perspective, this doesn't really make sense to me: it seems awfully difficult, to not say outright impossible, to have a stall speed that is significantly higher than the landing speed. Intuitively, the two should be just about the same, or the landing speed should be higher than the stall speed.

  • Did the F-8 actually have a stall speed of around 1.6 times its landing speed as suggested?
  • Is that even possible?
  • What were the stall and landing speeds of the F-8?
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    $\begingroup$ I'm imagining a landing procedure involving approaching the landing strip from below and following a parabolic flight path to get sort of dumped onto the runway. If you're trying this without the flaps, that is xD $\endgroup$ – bendl Oct 17 '17 at 18:22
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The stall speed your source is referring to may be the speed for a clean stall which means with the flaps are in flight position (= ).

Flaps on powered planes usually increase lift as well as drag. This means basically that you can fly slower and stall happens at a lower speed.

Here are the speeds from the F-8D flight manual (big pdf):

enter image description here

From the chart, in landing configuration with 19,000 lbs gross weight, the stall speed is ~113 knots.


does ground effect come in to play for landing scenarios? – Owen

Ground effect reduces the touch down speed by reducing the stall speed below the value mentioned in the manuals.

The strength of the ground effect depends on the construction of the plane. Low wing planes have stronger ground effect then high wing planes.
This means that the difference of landing speed and touch down speed is grater for a Low wing plane. On the other hand the ground effect increases the flare phase of the landing for a Low wing plane.

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    $\begingroup$ For completeness, since 133 kts is ~130 mph and Wiki is saying that the Navy asked for an airplane with a 100 mph stall speed, do you have another page from the manual that gives landing speeds? Or just a reason why the Navy let up on that criteria? $\endgroup$ – Marius Oct 17 '17 at 12:14
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    $\begingroup$ 113kts... which is still 30% over the original vision of a sub 100mph (<87kts) landing speed. This is also engine-off (idle) stall speed. A powered stall could be much slower at high AoA but certainly more of a stunt than standard landing procedure. The same manual gives standard approach as 130KIAS with the nose falling through at 90KIAS on rollout, so the <100mph landing speed was really just an initial concept, not really what ended up being practical. The flight manual also suggests to go around at >105KIAS with 4000ft runway remaining, so not exactly a short lander... $\endgroup$ – J... Oct 17 '17 at 12:15
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    $\begingroup$ @Marius Page 130 of the linked flight manual ;) $\endgroup$ – J... Oct 17 '17 at 12:15
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    $\begingroup$ does ground effect come in to play for landing scenarios? $\endgroup$ – Owen Oct 17 '17 at 17:48
  • $\begingroup$ @Owen updated the answer $\endgroup$ – Timothy Truckle Oct 18 '17 at 15:51
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Regarding the points about the possibility of having landing speeds lower than the stall speed, this entirely possible. Aircraft with large flap systems combined with the use of leading edge extensions can result in very large maximum lift coefficients for an aircraft. In some cases the maximum lift coefficient (cl max) in landing configuration can be more than double that of the clean cl. This is because flaps and leading edge extensions increase the camber and in some cases the area of the wing significantly.

Here is an example of a graph showing the effect of different flap types on section lift coefficient:

http://www.ballyshannon.com/air/aoaliftgraph.jpg

As to F-8 specifics, others have answered these questions better than I could.

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    $\begingroup$ By stall speed I am referring to clean stall speed which is usually the "stall speed listed for an aircraft" $\endgroup$ – DJ319 Oct 17 '17 at 12:55
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    $\begingroup$ Does the ground effect affect the landing stall speed? $\endgroup$ – chux Oct 17 '17 at 21:06
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    $\begingroup$ Ground effect would also increase the maximum Cl of the aircraft but ground effect is only considered to act up to 1 and a half wingspans above the ground. I doubt any manufacturer would include ground effect in their calculations of the landing stall speed. The calculations for ground effect are extremely complex and the region of the flight envelope they effect is small. I think if you are relying on ground effect for a nice slow landing you are in trouble, this is just an opinion though. $\endgroup$ – DJ319 Oct 18 '17 at 7:29

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