Banner Drag. A small plane pulls a square advertisement banner (10m x 10m) through the air at U = 25 km/hour. Estimate the total drag force (N) and power required of the plane to pull the banner for (a) using laminar flat plate results, (b) using turbulent smooth plate results in Table 9.1 [Note: the banner has two sides]. Ans OM: (a) F: 10⁰ N, P: 10¹ W; (b) F: 10¹ N, P: 10² W

Banner Drag. A small plane pulls a square advertisement banner (10m x 10m) through the air at U = 25 km/hour. Estimate the total drag force (N) and power required of the plane to pull the banner for (a) using laminar flat plate results, (b) using turbulent smooth plate results in Table 9.1 [Note: the banner has two sides]. Ans OM: (a) F: 10⁰ N, P: 10¹ W; (b) F: 10¹ N, P: 10² W

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.29P: Air at 20C flows at 1 m/s between two parallel flat plates spaced 5 cm apart. Estimate the distance...

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If a missile takes off vertically from sea level and leavesthe atmosphere, it has zero drag when it starts and zerodrag when it finishes. It follows that the drag must be amaximum somewhere in between. To simplify the analysis,assume a constant drag coefficient, CD, and constant verticalacceleration, a. Let the density variation be modeled by thetroposphere relation. Find an expression for thealtitude z* where the drag is a maximum. Comment onyour result.
The main cross-cable between towors of a coastal suspension bridge is 27.9 cm in diameter and 60 m long. Estimate the total drag force in (N] on this cable in crosswinds of 67.5 km/h. Assume the temperature of air is 15°C. Assume the drag coefficient is 1.5. The tolerance of your answer is 2%. PROPERTIES Air at 15"C Density = 123 kglm Dynamic viscosity 1.79 x 10 Ns/m?
Some engineers want a good estimate of drag and boundary-layerthickness at the trailing edge of a miniature wing. The chord and span ofthe wing are 6 mm and 30 mm, respectively and a typical flight speed is5 m/s in air (kinematic viscosity = 15 × 10−6 m2/s; density = 1.2kg/m3). An engineer may decide to make a superseding model withchord and span of 150 mm and 750 mm, respectively. Measurements onthe model in a water channel flowing at 0.5 m/s (kinematic viscosity = 1× 10−6 m2/s, density = 1000 kg/m3) give a drag of 0.19 N and aboundary-layer thickness of 3 mm. Estimate the corresponding values forthe prototype
The net drag of a moving body is produced by both pressure and shear stress effects. In most instance these two effects are considered together and an overall drag coefficient CD, defined as CD = D/(1/2 rU2A)。The drag coefficient are depend on what physical effects or dimensionless number.
Consider again a semi truck traveling at 55 mph on the freeway. The ambient air is at 1 atm and 80F. The trailer of the truck can be considered as a 8-ft-wide, 10-ft-high, 48-ft-long rectangular box. Assuming flat plate boundary layer behavior and no flow separation, estimate the drag force acting on the top and side surfaces and the power [hp] required to overcome this drag. Does the analysis seem reasonable for the actual drag force for the truck? Explain.
Skydiver Luke jumps with his parachute of diameter D = 12m out of an airplane. The combined mass of the parachute and Luke is 100 kg. The drag coefficient for the fully open parachute is C_{D} = 1.4 . Neglecting acceleration and considering a linear change of air density with altitude, estimate Luke's fall time between altitudes of 3000 m and 2000 m. For the density of air at these two altitudes, assume pair (3000m) = 1.0 kg/m³ and pair (2000m) = 1.1 kg/m³.
The 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 EN
An aircraft weight 980 KN flying steady and level at true airspeed of 720 km/hr at sea level. The airplane drag polar equation is Cp-0.015+0.05 C₁2, wing area is S=187 m². What is drag forces? If the aircraft flight at steady and sea level. (175 degree)
The parachute in the chapter-opener photo is, of course,meant to decelerate the payload on Mars. The wind tunneltest gave a drag coefficient of about 1.1, based upon theprojected area of the parachute. Suppose it was falling onearth and, at an altitude of 1000 m, showed a steady descentrate of about 18 mi/h. Estimate the weight of the payload.
Q1/ Boeing 737 - 60 flies at altitude 15000m above sea level with speed 85 m/s and total drag coefficient equal to ( 5) . Find the drag force at this fly condition. Given data IR=287,g=9.81 m/s2 , rho O=0.3648 kg/m2 and wing area = 120m^ ^ 2^ *
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 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.
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.