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53 Cards in this Set
- Front
- Back
What is the basic drag equation?
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Drag = CsubD x q x S =
CsubD x density x V^2 x S / 295 |
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The coefficient of drag is...
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ratio of drag pressure to dynamic pressure
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The aspect ratio =
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b^2 / S
where b is the wing span |
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When is a wingtip vortex formed?
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When higher pressure air below wing flows around wingtips into low pressure region, around tips, at the top
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Are low or high wing aircraft more effected by ground effect?
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Low wing
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What are the five types of parasite drag?
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Skin friction drag,
Form drag, Interference Drag, Leakage Drag, Profile Drag |
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What are three ways to reduce skin friction drag?
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Skin smoothness, laminar flow airfoils, and laminar flow control
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How do you find min drag?
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W / LD max
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For a jet, what performance points happen at LD max?
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Dmin
Best engine out glide Max endurance Best angle of climb |
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What is the third type of drag?
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compressibility and wave drag
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Wingtip vortices create a pattern of ____ ______
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disturbed air
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The net downwash about a finite wing tilts the lift vector _____
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aft
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The induced AOA is equal to ___ of the _______ angle
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half ; downwash
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Upon entering ground effect, what three things happen?
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Induced drag is decreased ;
Nose down pitching moment ; AS indicator reads low, falsely |
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Upon EXITING ground effect, what three things happen?
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Induced drag is increased ;
Nose UP pitching moment ; AS indicator reads higher, correctly |
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What is the equation for the pitching moment about the CG?
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MsubCG = CsubM x q x S x c
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How do wings contribute to static pitch stability?
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CG forward of AC: stabilizing
CG aft of AC: de-stabilizing |
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What is the effect of the fuselage on static pitch stability?
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de-stabilizing with gust
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How do the engine nacelles affect static pitch stability?
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If engines mounted aft of CG: stabilizing
If mounted forward of CG: de-stabilizing |
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What effect does the vertical tail have on yaw stability?
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Strongly stabilizing
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What effect does dihedral have on roll stability?
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Stabilizing for low wing
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Which has a lower stall speed with same wing area and weight? Straight or swept wing
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Straight has lower
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Compared to a straight wing, a swept wing must fly at a _____ AOA to achieve max lift.
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higher
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A straight wing stall is followed by a sudden reduction of CL. A swept wing does not have such a sudden drop off. T/F?
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True
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A swept wing aircraft is _____ sensitive to AOA changes than straight wing.
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less
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Lift distribution in the span wise direction is in the shape of a(n) _______?
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Ellipse
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Maximum lift in a straight wing occurs at the ?
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Wing root
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Lift on a straight wing is ____ at the wingtips?
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Zero
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Stall of a wing will occur where ratio of _____ CL and ____ CL is _____ ?
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local ; wing ; highest
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What is considered to be the most efficient planform?
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Elliptical; the entire trailing edge stalls at once
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The taper ratio of a _____ wing is zero.
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delta
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Stall starts where ____ _____ is highest
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wing loading
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Swept wing AC have (low/high) aspect ratios, which means they have HIGH induced drag
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low
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For a jet, the area slower than L/D max is referred to as ?
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region of reversed command
NOT backside of power curve |
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In the region of reversed command, less thrust is required to maintain altitude at a given airspeed. T/F?
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False
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Name three methods to slow an aircraft flying at min drag
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1) use speed brakes to increase drag
2) retard throttle and reduce thrust (won't be able to maintain altitude) 3) slowly increase AOA with control stick |
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What is the equation for rate of sink in FPM?
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101.3 X V [ (D - T) / (W) ]
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What controls the rate of climb or descent in steady flight?
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throttle setting
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Wind shears are caused by? (three things)
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Tstorms, fronts, and low-level jet streams
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The downward air flow below a Tstorm is called a ?
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downburst (most dangerous type of wind shear)
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What three types of bursts are created when a downburst hits the ground?
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Tailwind, headwind, and Xwind bursts
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What two factors must exist as a rule to have a possibility of LLWS?
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Temp gradient of >10 F across a front AND frontal speed of +30 kts
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What is the most hazardous condition caused by LLWS during takeoff?
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An increasing tailwind shortly after takeoff, resulting in pitch down motion = crash
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During approach to landing, what are the two dangerous LLWS conditions?
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1) headwind to tailwind shift (or reduced HW), causes pitch down and crash
2) Headwind shear causing pitch up and possible overshoot |
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During heavy rain during low level ops, Cd increase and lift values decrease at a studied amount around __%?
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30%
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According to a study, 0.1 inch of evenly distributed frost on the aircraft's wings will ______ stall speed by __%, effectively _______ the takeoff run
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increase ; 35% ; doubling
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What are the two types of "prop wash"?
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Thrust stream turbulence - high velocity air from props or jet exhaust (mostly a concern on ground)
Wake Turbulence - caused by wingtip vortices |
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L / D =
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CsubL / CsubD
W / D |
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The angle that RW leaving the wing makes with the free stream RW is called the _______ angle?
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Downwash
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The rearward component of the tilted lift vector is called ______ _____?
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induced drag
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Why is induced drag lower in ground effect?
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Because the downwash is reduced, the physical surface x ft below the plane blocks "shortens" the downwash
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What is the parasite drag (Dsub p) equation?
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Csub D (q)(S)
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On a total drag curve, where does L/D max occur?
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Intersection of the induced and parasite drag curves
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