Why still no dive acceleration difference?

[Crumpp]

To demostrate how important of 4-blade design compared to 3-blade,

That is a very generic graph with absolutely no conditions given. It is impossible to draw conclusions from about aircraft dive performance.

Good design can achieve the same efficiency and thrust with either 3 blades or 4 blades at the power levels of WWII aircraft.

As for propeller efficiency, there is a good reason why n=.85 is a good assumption to make for CSP propeller efficiency. Take the top of your single pitch effiiciency curve for the F4U and that is the efficiency a CSP will maintain throughout the envelope. It will adjust the blade angle to maintain that.

Examine n under various conditions and advance ratios in this article. This is a good primer for propeller performance btw.

You will see that n has a very small variance and even remains the same at different advance ratio because of the shape of the curve at that blade angle.

http://www.nar-associates.com/techni...ncy_screen.pdf

More blades = more drag but those airplanes have more thrust than the blades add drag because of their weight.

Align those aircraft by weight and you will see the important of it to achieving a high Vne.

That being said, mach limits and dynamic pressure limits have a much more practical impact on determining Vne.

Fw190A8A6? Bf109G6as Spitfire IX,XIV, these a/c are outdived by P47P51Tempy. Why?

Weight = additional available thrust. The propeller thrust is going to zero at the equilibrium point. It will vary but it not nearly the factor that weight becomes....

The excess propeller thrust is why the Bf-109 and FW-190 have such high initial dive acelerations under the conditions the article is talking about. If you dove all of those aircraft from Vmax, they would have no excess propeller thrust and would be using a component of weight as thrust.

Fw190A,as heavy as P51

Maybe, maybe not. Using the load plans, the P51D has the potential to add 550 more pounds of thrust at take off weight to increase its Vmax depending on the angle of dive. Granted that is not very much give the relationship of velocity and power. Power requirements are cubed in relation to velocity. Keep in mind your graphical representation from the 1940's flying magazine does not give us a scale but only shows relative advantage.

The radial of the FW190 will consume more gas and oil so its weight will change faster but the P51 has more gas and potential to change weight at a slower rate. The P51 also has a lower Drag picture so does not require as much thrust to achieve a higher speed. That is why it is faster than the FW-190A8 with a less powerful engine. Laminar flow has what is termed the "drag bucket" in the middle of the polar that occurs around cruise co-efficients of lift. It has no bearing on either low speed or Vmax performance except that laminar flow airfoils as a general characteristic exhibit lower CLmax. For your games purposes, that is irrelevant as you do not have to guess CLmax but can easily calculate it from stall speed with a given weight.

The Mustang achieves a higher Vmax in level flight so it was also achieve a higher Vmax in a dive provided it does not reach mach limitations or dynamic pressure limitations.

You can see from this sustained turn performance analysis the general effects of thrust and aerodynamic limitations of these designs.