Because of heat, & some of the characteristic change dramatically after certain air speed, so shape of the future aircraft will utilize this concept further.
9:28 This bit here has always been a bit misleading. The jumps and dips in lift coefficient as Mach number increases are being equated with jumps and dips in lift. This isn't exactly true, because the dynamic pressure is increasing with the square of Mach number for a given ambient pressure. So even if CL drops in a given transonic region, it's possible for the lift to increase due to the increase in dynamic pressure...
This video and the first part are extremely well done. In this part I think the discussion could be improved by clarifying what the frame of reference is, i.e. when there is a shock wave in front of the plane is it because we are considering the air to be moving at the speed of the plane? The ambient air is just standing still. No vehicle has touched it yet.... If there are pressure waves radiating out in front of it why do they magically congeal at a certain point?
Finally some accurate information regarding science. The only inaccuracy is the fact that they claim that temperature is the only factor that alters the speed for mack one which is not true. The simple equation actually is: pv=nrt This gives you the equivalent state of state of the air to retain the same density which is the real issue. And yes I am a real engineer.
The simple equation actually is: a=sqrt(gamma R T). For a calorically perfect gas in which Cv and Cp are constants, the speed of sound is a function of temperature only. And yes I am a real pilot.
@@piers4130you’re absolutely right. Not sure why this fella was trying to assert that density affects the speed of sound. Temperature is effectively the only thing that does. And I’m also an actual engineer. Just goes to show, just because someone says they’re an engineer doesn’t mean they know what they’re talking about.
