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The P-51 Mustang was the first aircraft intentionally designed to use laminar flow airfoils. However, wartime NACA research data shows that Mustangs were not manufactured with a sufficient degree of surface quality to maintain much laminar flow on the wing. The RAF found that the Bell P-63, despite being designed with laminar airfoils, also was not manufactured with sufficient surface quality to have much laminar flow.
The B-24 bomber's "Davis" airfoil was also a laminar flow airfoil, which predates the Mustang's. However, the designers of the B-24 only knew that their airfoil had very low drag in the wind tunnel. They did not know that it was a laminar flow airfoil.
The boundary layer concept is credited to the great German aerodynamicist, Ludwig Prandtl. Prandtl hypothesized and proved the existence of the boundary layer long before the Mustang was a gleam in anyone's eye.
Highly maneuverable fighter planes have no dihedral and some fighter aircraft have the wing tips lower than the roots, giving the aircraft a high roll rate. A negative dihedral angle is called anhedral. The AV-8B Harrier II above has a negative dihedral or anhedral
Ah no, the P-51s V-max was not better than the thick-winged Typhoon [525 IAS] significantly less than the 'laminar flow' winged Tempest [545 IAS], in fact the P-51s developed a bit of a blue-note terminal-velocity dive wing-shedding rep..but the P-51 was fast for the power it had available, on the level...
Ah no, the P-51s V-max was not better than the thick-winged Typhoon [525 IAS] significantly less than the 'laminar flow' winged Tempest [545 IAS], in fact the P-51s developed a bit of a blue-note terminal-velocity dive wing-shedding rep..but the P-51 was fast for the power it had available, on the level...
You might recall that the original P-51's performance was good, but not spectacular. My guess is that the wing performance was well below predicted.
- Luckily for the P-51, the British had the better performing merlin engine to use in it. In my opinion, this made all the difference.
Maybe the real-world 'laminar flow' wings were the best real world approximations of theoretical laminar flow wings? Some designers and producers doing their job better than another?
We can take a look at the available engine power the 1st Mustangs have at disposal. With engine same as at P-40D/E, the Mustang I was some 40 mph faster. The greater top speed was not something that could be attributed to the wing, but speed difference was simply to great.
The P-51B and later models, with Merlins comparable to the Spitfires VIII/XI, were some 30 mph faster than those Spits.
On the level, as opposed to going up or downhill.. The Mustang was not the fastest zoom/dive fighter inspite of its clean airfame..
Well... not really. It was virtually impossible to get the required profile accuracy and surface finish with the aircraft building techniques of the time.
The use of fiberglass and other composites has made production of these precision airfoils much easier. To give you an idea of how sensitive the NACA 6-series laminar profiles are to imperfection, sailplane owners would occasionally use 1000-grit sandpaper, attached to precision aluminum straight-edges to carefully smooth the leading edge and upper surface, even if they could not see any flaws. Some claimed significant performance gains.
Good points. The P-51 was a very clean aircraft. As a matter of fact, when I recently read a lament that there was not a greater attempt to improve the P-40, I realized that the North American engineers were familiar with the P-40 (having been asked to build it themselves) when they decided to design the P-51. In some respects, the P-51 was, indeed, an updated P-40.
The improvements would have been much greater, though, if the theoretical advantages of the laminar-flow wing were realized. On paper, there could have been a 25-30% reduction of drag from the wing. It should be mentioned, however, that even using today's construction techniques, such an improvement would be very, very unlikely. It turns out that the wind-tunnel data for those airfoils does not scale up accurately to the long cords and high speeds of the actual aircraft.
- Sailplanes (and military drones) have much narrower wings and fly at lower speeds.