4.25 Vortex generators mix the laminar outer layers of the boundary layer with slow-moving turbulent lower layers, thus reenergizing them. The plane is directly over a point on the ground that is 3 nautical miles from the takeoff point and the altimeter reads 12,152 feet. Max camber Power required is the power needed to maintain straight and level flight, i.e., to overcome drag and to go fast enough to give enough lift to equal the weight. ,8Ot_8KOgiy*I&lw4d^ "(y ,)r^oZq+#^?u^Jx!u3tpG_$=FJ[)M[U2>c^C:jf%r@cig=" Z#!E:C(qGL^P[li40M=MtvQy{vKHSv,@1i+6>8e;j>PYqV~zT5,e$CR%*n#f%CzL. QZ-o{s[h)9,zIxHDmfw8nO2yZOp_S,1,t'KXP9PXA x!`DVHw$Gn{?J dB~x%~ndpg+>2[B8J*3B}%\3iv}k^v~~h jKj 2qY!ZW` YWDv]m8keDzkbW`@w%=1CUd )bh#7 l&/B3AIuQLKH)q*#%U'9DIayeB47fcoP& I4xiZM A8xrABZ|*NTwD! Adapted from James F. Marchman (2004). It can tell us how much speed we can gain by descending to a lower altitude, converting potential energy to kinetic energy, or how we can perhaps climb above the static ceiling of the aircraft by converting excess speed (kinetic energy) into extra altitude (potential energy). 13.25 If an aircraft maintaining a constant bank angle increases its airspeed while maintaining a level, coordinated turn, what will the effect be on the radius of the turn? 13.3 (Reference Figure 5.4) What speed is indicated at point A? Do you think this is a reasonable speed for flight? But even in high-performance aircraft capable of steep climb angles where this is no longer the case, it can be geometrically shown that the steepest climb angle also occurs when the ratio of vertical speed to airspeed is maximized. If there is an increase in air pressure, it will: Affect air density by increasing the density. 1. Best Rate of Climb Fortunately, the answer is yes. It allows the aircraft to reach takeoff velocity at a lower groundspeed than for a no-wind condition. 11.9 If in descending, gliding flight, a component of ________ acts in the same direction as thrust. Power required is drag multiplied by TAS. For the prop aircraft Raymer defines TOP as follows: It should be noted here that it is often common when conducting a constraint analysis for a propeller type aircraft to plot the power-to-weight ratio versus wing loading rather than using the thrust-to-weight ratio. In this manner, we can find values of weight, wing area, and thrust that match our desired cruise capability. There are many good textbooks available on aircraft design and the Raymer text referenced earlier is one of the best. 2.6 The corrections that must be made to indicated airspeed (IAS) to obtain calibrated airspeed (CAS) are: 2.7 The correction from equivalent airspeed (EAS) to true airspeed (TAS) is dependent on: 2.8 An airplane is operating from an airfield that has a barometric pressure of 28.86 in. Figure 9.3: James F. Marchman (2004). How sensitive is the maximum range for the Cessna 182 to aspect ratio and the Oswald efficiency factor, i.e. The above relationship means that, for a given weight of the airplane, the rate of climb depends on the difference between the power available and the power required, or the excess power. We would then have to decide which of these three requirements was most important and which was least important and then start varying design parameters in an iterative manner until we got all three objectives to result in the same weight, wing area, and engine thrust. Using the PA-PRcurves in 2-3 for a propeller airplane find: _______ a. 3.9 For a cambered airfoil, the center of pressure (CP), 3.10 For a cambered airfoil, an increase in velocity results in, 3.11 A decrease in the AOA of any airfoil will result in, 3.12 The aerodynamic center (AC) is located at, 25% chord subsonically and 50% chord supersonically. It says that we need a higher thrust-to-weight ratio to climb than to fly straight and level. Figure 6.1: Finding Velocity for Maximum Range }*vxqS?Vi5Li^E[NIW_~;O`"P?yz].O^7x%zGv!6ytG6)R=7?Y>zJ4L} +|l\ } 17-57). Both approaches are minimizing the same angle on the right triangle comprised of the vertical speed, horizontal speed, and airspeed vectors. Note also that the units of the graph need not be the same on each axis for this method to work. High thrust will minimize the takeoff ground run but once thrust becomes as high as the weight of the plane we might as well take off vertically! 10.5 What effect does a tailwind have on takeoff performance? 8.20 As altitude increases, power available from a turboprop engine _____________. T/W = (qCD0)/(W/S) + (kn2/q)(W/S) + (1/V)dh/dt + (1/g)dV/dt . Maximum rate of climb for a propeller airplane occurs: at (PA-PR)MAX The lowest point on the PR curve is (L/D)MAX False Propeller aircraft are more efficient than jet aircraft because they process more air and don't accelerate it as much Turboprop aircraft are classified as power producers because: 13.8 (Reference Figure 5.4) An aircraft flying at 200 knots can pull how many G's before stalling the aircraft? See Page 1. While you are at it, just the sake of curiosity you might want to also calculate the arctangent of (vertical speed / airspeed) for the same data point. The method normally used is called constraint analysis. With metric units for speed (meters per second), this is the case. Don't let the length of this answer fool you, it is actually the fastest path to a solution, starting from what we're given to work with in the original question. 6.24 For a thrust-producing aircraft, the maximum climb angle occurs where the maximum _________ exists. It is called: AERO 1020 Final Review: All Past Test Q's/A's, Materials Science and Engineering: An Introduction, CT Basics 2.0 | Module 1: CT Fundamentals Test, MKT201 700 FULL CHAP-Key 700 Trung sa. Calculate (or find in Table 2.1) the approximate Pressure Altitude: 2.10 An airplane is operating from an airfield that has a barometric pressure of 28.86 in. From the above it is obvious that maximum range will occur when the drag divided by velocity ( D/V) is a minimum. To obtain best range the pilot now must, 8.2 Maximum rate of climb for a propeller airplane occurs at, 8.3 The turboprop aircraft has its lowest specific fuel consumption at about 25,000 feet altitude because, This is a compromise between (a) and (b) above, 8.4 The lowest point on the Pr curve is (L/D)max. 3.18 Critical angle of attack can be defined as: 3.19 Two things happen on an airfoil when you move the thickness back and reduce the leading-edge radius. 1.1 Aerodynamic Force (AF) resolves in which aerodynamic components? This is not a condition which we have studied earlier but we can get some idea of where this occurs by looking at the plot of drag versus velocity for an aircraft. 3.2 An aircraft in a coordinated, level banked turn. xYr7 _+(DL/HHMl>K miD%D./3QgBNgl<=Had5>fzhIQ6?|6]ot@{y Along with power setting but that one is somewhat self explanatory. The only problem is that we would find that their relationships in cruise arent necessarily the same as they are in takeoff and landing. '!,9rA%-|$ikfZL G1.3}(ihM For example you can choose a point where the straight line crosses one of the airspeed or vertical speed indices, or where it crosses an intersection of both airspeed and vertical speed indices. 5.21 Wingtip vortices are formed by higher-pressure air beneath a wing moving into __________ pressure air above the wing. Raymer also suggests multiplying the first term on the right in the distance equation above by 0.66 if thrust reversers are to be used and by 1.67 when accounting for the safety margin required for commercial aircraft operating under FAR part 25. 13.13 (Reference Figure 14.10) What angle of bank must an airplane maintain at 380 knots to achieve an eight degrees per second rate of turn? Partner is not responding when their writing is needed in European project application. For example, if the hub-to-ground measurement is 45 inches, subtracting 9 inches will leave an effective radius of 36 inches. What is the mass of the airplane? The more efficient a plane is in things like cruise the lower its value of T/W. Match the type of engine and the type of propeller where the advantages of each are utilized and nothing is wasted. 12.11 What two things are necessary for an aircraft to enter a spin? 7.19 Increasing the weight of a thrust-producing aircraft also increases the value of (L/D)max. Once the value of TOP has been found the relationship above is plotted to give a straight line from the origin of the constraint analysis graph. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. It only takes a minute to sign up. The formula is derived from the power available and power . What other design objectives can be added to the constraint analysis plot to further define our design space? This relationship proves to be a little messy with both ratios buried in a natural log term and the wing loading in a separate term. 11.23 If an aircraft traveling down a runway has a tire pressure of 200 psi and no other information is available, the approximate speed to which total dynamic hydroplaning may occur is __________. The mass flow depends on, 6.5 Specific fuel consumption of a turbine engine at 35,000 feet altitude compared to that at sea level is, 6.6 Fuel flow for a jet at 100% rpm at altitude compared to that at sea level is, 6.7 A pilot is flying a jet aircraft at the speed for best range under no wind conditions. 1.11 Equilibrium is defined as "a state of balance or equality between opposing forces." Arc Sine ratio of Vv/Airspeed = climb angle A tailwind is encountered. The goal of maximum wing loading may not be as obvious to the novice designer but this means the wing area is kept to a minimum which gives lower drag. This data can give us a place to start by suggesting starting values of things like takeoff weight, wing area, aspect ratio, etc. 5.3 An aircraft will enter ground effect at approximately what altitude? One finds the desired takeoff distance in feet on the vertical axis and projects over to the plot for the type of aircraft desired, then drops a vertical line to the TOP axis to find a value for that term. 2.22 _____________________ results when the CAS has been corrected for compressibility effects. Then the solution is the point with the steepest angle from the origin of the graph. RWY 27L & 27R), and the winds are 360/5, which choice(s) is/are true? 5.20 The most aerodynamically efficient AOA is found at. Rate of climb at maximum power for a small aircraft is typically specified in its normal operating procedures but for large jet airliners it is usually mentioned in emergency operating procedures. We can use the above relationship to make plots of the thrust-to-weight ratio versus the wing loading for various types of flight. The greatest danger(s) is that. Looking again at the aircraft in Homework 8 with some additional information: 1. By optimum we mean that we are looking for the minimum thrust-to-weight ratio that will enable the airplane to meet its performance goals and we would like to have the highest possible wing loading. The constraint analysis may be performed several times, looking at the effects of varying things like wing aspect ratio on the outcome. 8 0 obj Hg and a runway temperature of 20C. The maximum rate of climb at a given speed will then depend on the difference between the power available from the engine at that speed and the power required for straight and level flight. Under what conditions can the maximum angle of climb be achieved for jet and propeller aircraft? 12.21 When taking off in a microburst, a pilot should be aware of what change in performance when going from a headwind to a tailwind? For rate of climb, the maximum rate would occur where there exists the greatest difference between power available and power required (Fig. 13.24 If an aircraft maintaining a constant bank angle increases its airspeed while maintaining a level, coordinated turn, what will the effect be on the rate of turn (ROT)? Effect of Desired Landing Characteristics on Aircraft Design Space. CC BY 4.0. It does this by looking at two important ratios, the thrust-to-weight ratio (T/W), the wing loading or ratio of weight-to-planform area (W/S). 2.15 The standard unit of measure for static pressure for pilots and altimeter settings is: 2.17 At _____________ altitude the static pressure is about half that at sea level. The plot that will be different from all of these is that for takeoff. In the equation above we have a very general performance equation that can deal with changes in both speed and altitude and we find that these changes are functions of the thrust-to-weight ratio, T/W, and the wing loading W/S. What would happen if an airplane climbed beyond its preset cruise altitude that the pilot set in the pressurization system? In the proceeding chapters we have looked at many aspects of basic aircraft performance. Each plot of the specific power equation that we add to this gives us a better definition of our design space. The maximum angle of climb occurs where there is the greatest difference between the thrust available and the thrust required. In computing FAR 25 climb performance, the effects of one engine inoperative must include not only a decrease in thrust, but an increase in drag due to: 1) windmilling drag of inoperative engine or windmilling or feathered drag of propeller. We need to note that to make the plot above we had to choose a cruise speed. 6.21 The lowest values of ct occur between 95 and 100% rpm. stream Stall Cutoff for cap W over cap S values. CC BY 4.0. 9.10 As a power-producing aircraft burns off fuel, ROC will ___________ for a given velocity. Substituting this for drag in the equation and dividing the entire equation by V we can get: (T/W) = [(CD0 + kCL2) V2S) /W] + (1/V)dh/dt + (1/g)(dV/dt). Normally we would look at turns at sea level conditions and at takeoff weight. If, for example, we went all out to create a plane that could takeoff in a very short distance and then look at its performance in straight and level cruise we would probably find that it isnt very good. Connect and share knowledge within a single location that is structured and easy to search. 3.2 The main variable(s) in the geometry of an airfoil are: 3.3 The angle between the relative wind and the chord line of an airfoil is the, 3.4 For a symmetrical airfoil, at 0o AOA, air passing over the wing results in, An equal increase in velocity over the top and bottom of the wing. I've made the recommended changes and have decent reverse thrust. 9.5 To obtain maximum glide distance, a heavily loaded airplane must be flown at a higher airspeed than if it is lightly loaded, 9.6 The increase in the Pr curves for a weight increase is greater at low speeds than at high speeds because the increase in. 13.14 (Reference Figure 14.10) What airspeed must an aircraft maintain at 50 degrees of bank to achieve 10,000 feet radius of turn? Figure 9.1: James F. Marchman (2004). One way to approach this would be to go back to the equations in earlier chapters and iterate among them, trying to find wing areas, weights, and engine sizes that would accomplish our design objectives. Constraint analysis is essentially a way to look at aircraft weight, wing area, and engine thrust for various phases of flight and come to a decision about meaningful starting values of all three parameters for a given set of design objectives. Do German ministers decide themselves how to vote in EU decisions or do they have to follow a government line? pressure altitude / nonstandard temperature conditions. But through good use of things like constraint analysis methods we can turn those compromises into optimum solutions. 3. mean camber line Now, to simplify things a little we are going to use a common substitution for the dynamic pressure: We will also define the lift coefficient in terms of lift and weight using the most general form where in a turn or other maneuver lift may be equal to the load factor n times the weight. An iterative solution may be necessary. 12.6 The best way to control airspeed is with the ___________, while the best way to control altitude/descent rate is with the ____________. Aircraft Design: A Conceptual Approach, AIAA, Washington, DC. We could put these limits on the same plot if we wish. You are correct that Vy will give you the max RoC. 3.7 The Center of Pressure __________ move with a change in AOA for a symmetrical airfoil, while it ____________ move with a change in AOA for a cambered airfoil. Excess thrust is the difference between the total drag of the aircraft, and the thrust output of the powerplant. 11.12 Which of the following aircraft derive more lift due to high power settings? Another factor to consider would be the desired maximum speed at the cruise altitude. 5.2 Wingtip vortices contribute to which type of drag? Modern propellers on larger aircraft would always be equipped with automatic feathering provisions. What is the typical climb angle (versus the ground) of a single engine piston plane? Figure 9.7: Kindred Grey (2021). This limits your maximum allowable propeller diameter to 72 inches (36" x 2" = 72"). 2.19 Standard temperature for degrees C is ___________. These two ratios are tied together in aircraft performance through the same power relationship that we looked at when we first examined climb and glide. The size of the turn circle as determined by the angle of bank and airspeed, The number of degrees per second that the aircraft is turning as determined by the angle of bank and airspeed, 13.12 (Reference Figure 14.10) An aircraft traveling at 150 knots and 45of bank will have a radius of turn of. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 11.17 Headwinds and tailwinds affect the landing distance by the same amount as they affect the takeoff distance. Steeper approach angle with a touchdown closer to the approach end of the runway, 11.22 A high roundout during landing may result in ______, Slowing of the aircraft well above the runway with increasing angle of attack. 12.22 According to the textbook, one study showed that 0.1 in. (As a point of trivia, it looks like if the horizontal units on your graph are knots and the vertical units are feet/min, then the angle computed with the arcsine is about 4% larger, or about 0.6 degrees larger, than the angle computed with the arctangent.). Thanks for contributing an answer to Aviation Stack Exchange! 7.22 The value of (L/D)max changes when the gear and flaps are lowered. 10.16 As a rule of thumb, a 5% increase in takeoff distance can be expected for every _______ of uphill slope. 5.9 Drag due to the interference of boundary layers from different parts of the aircraft is known as, 5.10 The type of drag which is of particular importance to helicopter pilots is, 5.12 The most employed technique for reducing induced drag on modern aircraft is the use of, 5.14 Laminar flow airfoils have less drag than conventional airfoils, 5.15 Laminar flow airfoils have less drag than conventional airfoils because, 5.16 An airplane flying at CL MAX will have.
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