First, let me say I am not a engineering student but just a average person trying to get his pilots license and enjoy working with aerospace problems. My problem is: “An aircraft is flying at 150 mph. The atomspheric pressure is 14.1 lbs./sq in and the temperature is 50 degrees F. Find the total or stagnation pressure at the point on the airfoil. If the pressure at a point on the upper surface of the airfoil is measured and found to be 13.9 lbs/sq in., what is the local air speed at this point?” I am trying to use the Bernoulli principle to solve this problem P1 + ½ρV^2 = P2 + ½ρV^2 I have converted a few things to help work with the equation: 150 mph x 1.4667 = 220 ft/sec 50 F + 459.6 = 509.6 degrees Rankine. 14.1 x 144 = 2030 lbs/sq. ft. I understand that as the velocity increases the pressure decreases in the venturi tube and that as velocity decreases the pressure will increase but I am still having trouble solving the entire equation and I guess understanding how to calculate everything in the problem. Here is what I have though and please correct me if I am wrong or have mathematical errors or failed reasoning 101. Solving for P1 (dynamic pressure) 2030 + ½ (.0023769 slugs)(220)^2 =2030 + (.00118845)(48400) =2030 +57.52 =2087 lbs/sq ft. How do I go about solving the the second part of the word problem if the pressure is measured at 13.9 lbs/sq in., what is the local air speed? Do I just plug in 2001 lbs/sq. ft (13.9 x 144) for P2 and solve for V^2? Also, let me apologize for the ole school units. My book came from a old bookstore and it by a professor at University of Kansas (Vincent Muirhead). I would like to have the Intro to Flight by Anderson but I refuse to give 180.00 for a book.