The success of the P-51 wasn't because its aerofoil was symmetrical but because of its contours and point of maximum thickness.
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
The success of the P-51 wasn't because its aerofoil was symmetrical but because of its contours and point of maximum thickness.It is definitely a complicated matter. As I heard, the PZL.37 was used partially symmetrical airfoil by accident and out of necessity. The constructor had to fit the bombs inside the wings. But he was highly skeptical. He believed that an airplane with symmetrical airfoil would fly worse. As it turned out, he flew quite well, but his "father" didn't understand it. So - before that people had to think that symmetrical airfoil was a bad idea. What's more - the Germans captured PZL.37, the Soviets captured PZL.37 and ... they did not copy this idea. And they certainly had smart engineers too.
Can someone explain to me in a simple way how a laminar wing lifts an airplane? I always thought an airplane wing had to be convex at the top and flat at the bottom. This causes a difference in air velocity at the top and bottom. And that causes the pressure difference. But when I look at the P-51 wing, I have the impression that it is equally convex at the top and bottom. See figure:
http://historynet.com/wp-content/uploads/2015/07/air_flow.jpg
At school they were perhaps teaching the whole subject of relationships between pressure volume and temperature (Boyles Law etc), generating lift by increasing velocity over the top of the wing and therefore reducing pressure is one example of it.
Thats why I thought it was part of teaching the basic laws of physics rather than how an aircraft flies.One hopes no one is repeating the "Bernoulli effect causes lift."
Probably. A lot of teachers have used the Bernoulli theorem to explain lift. It's a nice story, but it's also wrong. Lift is caused by the deflection of the airflow. You can see this by looking at a different lifting surface: the wing on sail boat, where there is no difference between the length of the trip on the suction and pressure sides
I knew something like that would happen, back to google.Couple of thoughts,, re: Mustang wing through P-51K (but not the LW F/G/H) - NAA/NACA 45-100 airfoil.
I cover all of this and more in my new book Appendices - including the development and tools and methods to arrive at the airfoil co-ordinates beginning with
- Had 1.29% Camber WS 0 through 215, T/C constant 37.2% - then 1.34% at tip chord t tip. The Tip Chord differed in mac TC at 48.01% to mitigate some low speed stall issues.
- T/C at root, WS=0 was 16.13%, tapering to 11.46% at WS=215.
- Geometric twist - total 1 degree 53 minutes 6.43 seconds. + 0.59 minutes 56.46 sec at WS=0; -0.53 minutes 9.7 sec at WS 215.
desired pressure distribution, CM and CL vs AoA
While some small laminar flow properties were achieved (largely by manufacturing processes in fabrication, flush rivets and sealing/priming and sanding leading 40% Chord. the truly dominant values were Low Drag, delayed Mcr and location of shock wave to max T/C which greatly reduced effect of moving CP aft of 25% Chord. The P-51 just didn't have severe pitch down issues at critical Mach.
It only works at high speed and there is no free lunch. Cant find a picture of an Arrow landing but this is how Concorde landed at approximately 160Kts. it needs a large AoA to generate the lift even at those speeds because it was built to cruise at Mach 2. A paper dart can only hold together at throwing speeds, use an elastic band and it becomes a piece of paper again.I understand the idea that a non-zero angle of attack causes the plane to be lifted up. Indeed, when there is flat cardboard outside the window of a fast moving car, this effect can be achieved. But how is such "wing" different from the tail elevator? I remember the movie about the history of building the Avro Canada CF-105 Arrow. There is a scene where a guy makes a paper plane as a "model". Then I thought: "OK, such a >>plane<< can have wings made of a flat sheet of paper because it is light, gravity does not pull it strongly to the ground, but a real heavy plane is another matter, it must have some lift effect."
If you can get such a wing to warp to provide control.Looks like I opened a Pandora's Box ... Because my question caused an avalanche of higher math and some mysterious words. But, to put it simply: the wings of the Blériot XI could have been quite flat? And symmetrical?
If you can get such a wing to warp to provide control.
Basically you're dealing with both variables acting together in tandem.When I was a kid I used to think that this is how an airplane wing works. But then in school during the lesson I heard that the "lift" of the plane is the result of the difference in airspeed over the wing and under the wing. And that for the same reason a strong wind lifts the roofs of houses (because they are convex at the top). So ... something must be wrong with school education.
I am not a pilot or aviation engineer, there are some who post here as you have seen. The Bleriot XI flyer only had elevator controls on the tips of the rear elevator I doubt if that would give anywhere near enough, would you fly it? Probably would, why not give the wings some dihedral to help self levelling and have them straight with the elevator used to give a small AoA. One aircraft I know was built like your model was the Armstrong Whitworth Whitley - Wikipedia It was good for take off and landing but in level flight meant a nose down attitude which was very draggy.The rudder and elevator on the tail are not enough? (maybe you are surprised that I do not understand it, but I rarely fly with planes and only as a passenger, not a pilot)
And another question: if I make such an airplane model:
model-01
... (flat wings, but "enlarged" angle of attack) and mount the engine in it, will it fly correctly? Let's say "the wings" are the center of balance. Of course, I mean "generally correctly", in the sense of: it will take off and move forward ... ?
Couple of thoughts,, re: Mustang wing through P-51K (but not the LW F/G/H) - NAA/NACA 45-100 airfoil.
I cover all of this and more in my new book Appendices - including the development and tools and methods to arrive at the airfoil co-ordinates beginning with
- Had 1.29% Camber WS 0 through 215, T/C constant 37.2% - then 1.34% at tip chord t tip. The Tip Chord differed in mac TC at 48.01% to mitigate some low speed stall issues.
- T/C at root, WS=0 was 16.13%, tapering to 11.46% at WS=215.
- Geometric twist - total 1 degree 53 minutes 6.43 seconds. + 0.59 minutes 56.46 sec at WS=0; -0.53 minutes 9.7 sec at WS 215.
desired pressure distribution, CM and CL vs AoA
While some small laminar flow properties were achieved (largely by manufacturing processes in fabrication, flush rivets and sealing/priming and sanding leading 40% Chord. the truly dominant values were Low Drag, delayed Mcr and location of shock wave to max T/C which greatly reduced effect of moving CP aft of 25% Chord. The P-51 just didn't have severe pitch down issues at critical Mach.
Completely aside from the airfoil effects, separating the boundary layer from the rest of the flow had some important benefits. Note that the P-51 grew an upper lip on its belly intake. The P-38 had a lip added to the side mounted radiators, which improved cooling without reducing radiator size. The P-80 had splitter plates added to the jet intakes, to eliminate duct rumble that came from the boundary layer and outer air mixing in the intake duct, as well as providing a suitable air source for the ECS cooling.
I am not a pilot or aviation engineer, there are some who post here as you have seen. The Bleriot XI flyer only had elevator controls on the tips of the rear elevator I doubt if that would give anywhere near enough, would you fly it? Probably would, why not give the wings some dihedral to help self levelling and have them straight with the elevator used to give a small AoA. One aircraft I know was built like your model was the Armstrong Whitworth Whitley - Wikipedia It was good for take off and landing but in level flight meant a nose down attitude which was very draggy.