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The German Zeppeins of World War I were dirigibles with the following typical characteristics:
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- A smooth aluminum sphere hangs in air on a 0.5 m-long cable. The sphere has a diameter of 10 cm and weighs 1.5 N (it is hollow). It is observed that a steady wind causes the sphere and cable to be displaced so that = 20°. Assume that the weight of the cable and the drag force on the cable are negligible. (a) What is the magnitude of the (horizontal) drag force on the sphere? (b) What is the wind speed U? Answer: (a) D≈ 0.55 N, (b) U≈ 15 m/s Uarrow_forwardIcebergs can be driven at substantial speeds by the wind.Let the iceberg be idealized as a large, flat cylinder, D >> L,with one-eighth of its bulk exposed, as in Fig.. Letthe seawater be at rest. If the upper and lower drag forcesdepend on relative velocities between the iceberg and thefluid, derive an approximate expression for the steady icebergspeed V when driven by wind velocity U.arrow_forwardFluid Mechanics Problem: A ship is 150 m long and has a wetted area of 5000 m2.If it is encrusted with barnacles, the ship requires 7000 hp to overcome friction drag when moving in seawater at 15 kn and 20oC. What is the average roughness of the barnacles? How fast would the ship move with the same power if the surface were smooth? Neglect wave drag. Note: Treat the ship hull as a flat plate. Use eq. 7.48b to find effective barnacle roughness height.Use equation (7.45) White for the drag coefficient CD = D/.5pV2A , where A is the hull (plate) area, to find the ship velocity for smooth plate.arrow_forward
- The airplane as described has a stalling speed at sea level of 100 mph at the maximum take-off weight of 15,900 lb. The ambient air density at standard sea level is 0.002377 slug/ft3. Calculate the value of the maximum lift coefficient for the airplane.arrow_forwardDrag Force on a Raindroparrow_forwardThe large block shown is x = 72 cm wide, y = 54 cm long, and z = 9.0 cm high. This block is passing through air (density of air p = 1.43 kg/m³) at a speed of v = 8.61 m/s. Find the drag force F41 acting on the block when it has the velocity vj and a drag coefficient I = 0.812. V2 Fa.1 N %3D Find the drag force F42 acting on the block when it has the velocity vz with a drag coefficient I = 0.893. F42 N Find the drag force Fa.3 acting on the block when it has the velocity vz with a drag coefficient I = 1.06. F4.3 = N ENarrow_forward
- Show stepsarrow_forwardAnswer this olearrow_forwardYou are designing an airfoil for a new hobby RC plane. Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm. Here, “a” is the depth of your wing and “b” is the thickness. Your plane travels through the air at approximately 20mph (8.9m/s). As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the Reynold’s number? Hint: “D” is taken to be the thickness for an elliptical crosssection. b) What is the Nusselt number? c) What is the convection coefficient? d) What is the average temperature of your wing? Assume an ellipse perimeter of approximately 200mm.arrow_forward
- You are designing an airfoil for a new hobby RC plane. Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm. Here, “a” is the depth of your wing and “b” is the thickness. Your plane travels through the air at approximately 20mph (8.9m/s). As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the average temperature of your wing? Assume an ellipse perimeter of approximately 200mm.arrow_forwardTheory of Flight A- Airbus 320 fly in steady level flight with altitude 11000m, find the lift force required to steady level flight. At steady level flight aircraft has weight as (65000 kg), wing area is (124 m?), aircraft speed is (147 m/s) and lift coefficient is (1.3) Atmosphere data for 11000m shown in table below Туре of atmosphere layer Stratosphere Rang (m) Temperature gradient (a) k/m Temperature (k) 0-11000 -0.0065 288-216.6 Given data (R=287, g=9.81 m/s?, and po=1.225 kg/m³)arrow_forwarda)What is the impact of increasing Reynolds number on skin friction and pressure drags over an airfoil? What can be happened for separation in this case? b) What is an adverse pressure gradient and where does it occur on an airfoil (show that on a sketch)? c) Why lift-to-drag ratio is an important parameter for an aircraft? d)How can changing in altitude affect the aircraft power required, PR? Show thatmathematically and graphically?arrow_forward
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