The length of a proposed submarine is 100 m and the planned speed is 20 km/hr. In order to estimate the power requirements for the propulsion system, the vehicle resistance must be evaluated. It was proposed to build a wind tunnel model of the submarine and test it in air. If using the similitude assumption (e. g., keeping Re the same), what is the required length of the wind tunnel model if test speed is 80 m/sec

Afour cylinder four-stroke in-line engine has a stroke of 160mm, connecting rod length of 150mm, a reciprocating mass of 3kg and its firing order is 1-3-4-2. the spacing between cylinders is 100mm. i. show that the engine is in balance with regard to the primary inertia forces and primary 3. a and secondary inertia couples. li determine the out of balance secondary inertia force ii. propose ways of balancing this out of balance force and discuss the challenges that will arise