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Session Speaker M. SivapragasamSession 04Aircraft Accelerated Flight 2 M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologySession ObjectivesAt the end of this session, student will be able to: Differentiate take off and landing requirements of different types of aircraftCalculate the take off performance of an aircraftExplain balanced field length requirements for aircraft take offCalculate the landing performance of an aircraftCalculate the climb performance of an aircraftM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyConventionalShortSuper shortExtremely shortVertical Rocket assisted

Types of TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & Technology

Take off using a conventional runwayGround roll distance is determined by the requirement to clear a 50ft (35ft for commercial) obstacle

Land on a conventional runway and decelerate after clearing a 50ft obstacleFlare is a deceleration maneuver to reduce airspeed and altitudeConventional TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off and clear 50 foot obstacle in between 1000 and 1500 ftLand and stop between 1000-1500 ft after clearing 50 foot obstacle

Aerostar 600Cessna 182De Havilland Canada Dash 7Short TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off and clear 50 foot obstacle in between 500 and 1000 ftLand and stop between 500-1000 ft after clearing 50 foot obstacle

SSTOL concept from Advanced CompositesAnronov AN-28Great Lakes Sport TrainerSuper Short TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off and clear 50 foot obstacle in under 500 ftLand and stop under 500 ft after clearing 50 foot obstacle ESTOL

Aeronca ChampionSherpha K650TCanaero ToucanExtremely Short TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyNo need for runway or obstacle avoidance requirementAircraft can take off and land without the need for a runwayF35

The Harrier and V-22 Osprey Vertical Takeoff VehiclesVertical TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyThe use of rockets (usually solid rockets) to shorten takeoff distanceC130

To decrease landing distance use rockets opposed to direction of flight to fall out of the sky.

Rocket-assisted TO/LM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake-off and LandingTake-off Field LengthThe take-off field length is generally split into three sections:Take-off Distance: The ground distance required from brakes release at the start of the runway, accelerating from rest until the aircraft reaches a 'screen' height above the runway.Take-off Run: The ground distance required from brakes release at the start of the runway, accelerating from rest until the aircraft reaches a point between lift-off and a 'screen' height above the runway. This point can vary between different airworthiness requirements.M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off Field LengthAccelerate-Stop Distance: The ground distance required from brakes release till the aircraft reaches a decision speed and then the brakes are applied until the aircraft comes to a complete stop.

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off Distance ComponentsThe take-off distance can be split into four different phases:Ground accelerationRotation phaseTransition phaseInitial climb out to screenTypically, the aircraft take-off manoeuvres corresponding to the take-off distance phases listed above can be split as seen in figure

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off Distance ComponentsGround acceleration until lift-off speedAir acceleration until climb safety speedTransition to climbClimb to required altitudeSpeedJAR25Decision speed (V1)V1 > VEF > VmcgRotation speed (VR)VR > V1VR > 1.05VmcaMinimum take-off safety speed (V2)V2 > 1.2VsV2 > 1.1VmcaM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTake off Distance Components

Before the aircraft becomes airbornethe aircraft is accelerating along the ground until rotation at the rotation speed (VR)transition to lift-off speed (VLOF)and climb out to achieve take-off safety speed (V2) at the screen, usually 35 ft.M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunTo calculate the ground roll, we need to write the equations of motion for the vehicle as it moves down the runway.See figure below

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunThe forces that act on it are the aerodynamic forces ofLift and Drag (L and D), the thrust force (T), The ground normal force (R) and the ground friction force (R), where is the coefficient of rolling friction.We can now write the equations of motion along the runway and perpendicular to it.M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground Run

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyFriction Coefficients ()Runway SurfaceFriction Coefficients ()CONCRETEwetdry0.03 - 0.0350.04 - 0.05Grasswetdry0.07 - 0.10.09 - 0.13Hard Snow-0.05 - 0.055Dry Soft Groundsand0.2 - 0.3M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunRe-arranging we have During takeoff, high lift devices like Flaps, Slats etc are deployed and the landing gear is also exposed. Here C Lg and C Dg refer to lift and drag coefficients of the aircraft in such a configuration. Obviously both the coefficients are large

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunIn order to be able to integrate the above equations, we need some functional relationships. We assume that Thrust T depends on V as follows

Substituting the above assumption into the equations derived earlier and collecting terms of V 2 M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunHere, A and B are defined as:M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunDividing both sides by V and realising V = (ds/dt) and rearranging we haveIn the previous slide we had shownHere if we assume A and B to be constant as a first approximation,The above equation for ds can be integrated between V1 and V2M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunHere we consider the case of staring from rest then the above equation simplifies toWhere, A and B are defined as:M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunAs before we want to find the condition when S is minimumThis happens when we have Maximum value for A which depends on Thrust/weight ratio and friction coefficient Minimum value for B, here we have control only over C Lg and C DgReduce this by cleaner aircraftM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground RunImprove C L g by better high lift devices and also higher angle of a/c during ground runSimply making the front landing gear taller achieves this !!We can find the optimum value by differentiating and equating to zeroM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTakeoff : Ground EffectWhen an aircraft is flying near the ground its efficiency improvesBecause of interference between the horse-shoe vortex and groundOne of the methods for correcting for ground effect is to modify value of K h = height of the wing above the groundb = wingspane = Oswald efficiency factorM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyLanding RunThe opposite of the takeoff procedure is the landing procedure.Just as in the takeoff, the landing maneuver consists of two parts:The terminal glide over a 50 ft obstacle to touchdownThe landing ground runSome calculations include a flare from the landing glide to the touchdown.However, for a maximum performance landing (short field landing procedure), very little flare is used.M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyLanding RunHere we will neglect the flare portion of landing and assume the aircraft touches down at slightly higher speed than it would after flaring.The equations of motion governing the landing ground run are the same as those for takeoff. However, the constants A and B can be quite different. Thrust can be zero or even negative (reverse thrust)The runway rolling friction can be much larger due to braking.M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyLanding RunThe boundary conditions are differentAt the beginning of the ground roll the velocity is that at touchdown, VTDAt the end of the ground run, the velocity is V2, usually zeroDifferential equation of motion for the landing run is the same as that for takeoff:Results are different

For V 2 = 0, we haveM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyBalance Field LengthIn order for a multi-engine commercial aircraft to takeoff from a runway, the runway must at least be as long as the Balanced Field Length (BFL). BFL is determined by considering two options available to the pilot if an engine fails.continue the takeoff on the remaining engines to clear the 50 ft (15m) obstacle and establish a takeoff distanceapply the brakes as soon as possible after the engine failure and to bring the aircraft to a halt in some distance.If the two distances are the same, that distance is called the BFL M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyBalanced Field LengthAssuming a speed (and distance along the runway) when that the engine failure occurs.Continue the takeoff on the remaining engines and compute the additional distance for the vehicle to clear a 50 ft obstacle, determining the takeoff distanceStarting with the speed assumed in (1), assume two additional seconds go by and then the engines are shut down, brakes applied and the ground roll to stop calculated.M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyCompare the distance in (2) with that in (3).If the distance to stop is shorter than the distance to fly over the 50 ft obstacle, increase the guess in step (1).If the distance to stop is shorter than that required to clear the 50 ft obstacle, then decrease the failure airspeed in step (1). Continue this procedure until the total takeoff distance and the total distance to stop are the same.This distance will be the balance field length, and the associated velocity found is called the critical engine failure speedBalanced Field LengthM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyAll TO/L data recorded throughout entire flight test program

Tests devoted to TO/L done at:Various gross weightsClean and several dirty configurationsStandard to contaminated runway conditions

Must rely on statistical average of as many tests as possibleGreatly affected by factors that cannot be measured and properly accounted for

Typically delayed in flight test program b/c of amount of support and time required

Flight Test Basics M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyConducted prior to any TO/L tests due to:Always present possibility of a refused takeoff in those testsNeeded to determine parameters used in TO/L testsParameters:Thrust transientsDragRolling CfGround Handling

787 High Speed Taxi Test: Reached 100 knots first test, VR actually about 150 knots High-Speed Taxi TestM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & Technology

Vmc = minimum control speed (OEI)V1 = critical engine failure recognition speedVR = rotate speedVlo = liftoff speedV2 = cleared obstacle speed Takeoff Critical LocationsM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyRejected Takeoff Distance: The distance required for the vehicle to stop from full throttle at V1 speed for a specified altitude, weight, and configuration.

Also known as aborted or refusal takeoff

Rejected Takeoff Test

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTo reduce risk to multi-million dollar aircraft, brakes are first tested individually in a simulated environment.Rejected Takeoff Test

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyFull scale aircraft test- Aircraft is accelerated to V1 at max throttle- A 3 second delay given to simulate pilot time to recognize situation- Engines are set to max reverse and brakes are applied

Rejected Takeoff TestM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyAircraft Steady Gliding Flight

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyAircraft Steady Level Flight

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologySteady Climbing Flight

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologySteady Climbing, Descending Turn

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & Technology

Climbing Flight is angle between Tand Centre lineM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight small angle approximation

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & Technology

Climbing FlightM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Max Angle of climb

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Max Angle of climb

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight R/C

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight R/C For our idealized jet airplane, best rate of climb does not occur at minimum power requiredMaximum rate of climb occurs at the velocity where excess power is greatestThe velocity for maximum rate of climb is determined for any aircraft as follows :Plot power required and available versus true airspeedChoose the velocity where the distance between the two curves is greatest.

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Max R\C

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Effect of altitude

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Effect of altitude

Typical Thrust and Power change with altitudePower required reduces as density drops hence Drag reduces with altitudeHowever, Power available drops faster, hence R/C decreases with altitudeM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Propeller aircraft

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyClimbing Flight Jet Aircraft

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyCeilingThe ceiling is the altitude at which R/C has reached some minimum valueAbsolute ceilingIs defined as the altitude at which the R/C = 0Is dictated when PA is just tangent to the PR curveService ceilingis defined as that altitude where R/Cmax = 100 ft/min, is the practical upper limit for steady, level flightM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyProcedurecalculate values of R/Cmax for different altitudes, plot R/Cmax versus altitudeextrapolate this latter curve to 100 fpm and 0 fpm to get the the service and absolute ceilingsCeilingM. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyTime to Height

M. S. Ramaiah University of Applied Sciences#M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyExample: F-15 KWeapon launched from an F-15 fighter by a small two stage rocket, carries a heat-seeking Miniature Homing Vehicle (MHV) which destroys target by direct impact at high speed (kinetic energy weapon)F-15 can bring ALMV under the ground track of its target, as opposed to a ground-based system, which must wait for a target satellite to overfly its launch site.

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyGliding Relations

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyGliding Relations

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyMaximum Gliding Range

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyMaximum Gliding Range

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologySink Rate

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologySink Rate

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyL/D and Velocity for min sink rate

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyMustang Example

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyExample: High aspect ratio glider

To maximize range, smallest q occurs at (L/D)maxA modern sailplane may have a glide ratio as high as 60:1So q = tan-1(1/60) ~ 1qM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example Use the vehicle characteristics for the very large capacity transport aircraft A380 Estimate the rate of climb for this aircraft at two distinct points in the climb profile: 600 meters (2,000 feet) and 210 knots - IAS 8,000 meters (26,200 feet) and 290 knots - IAS Estimate the thrust produced by the engines under both conditions Find the Lift to Drag ratio for both conditions Assume the International Standard Atmosphere applies to both aircraft statesM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example An aircraft similar in size and performance as the Airbus A380Four turbofan engines each developing 34,400 kg (338,000 N) at sea levelMaximum takeoff mass is 540,000 kg. (1.188 million pounds)

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C ExampleVisualize the scene and sketch a free body diagram of the systemFor this analysis we will ignore the second term in the Right Hand Side(RHS) of the differential equation (acceleration term)The pilot is interested in climbing as fast as possible using all the engine thrust to climb

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C ExampleAircraft is treated a point mass for this calculationAnd we treat both start and end points

600 m600 mM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C ExampleStep 1: Estimate true airspeed using atmospheric modelStep 2: Estimate the lift coefficient needed to sustain flight using the basic lift equationStep 3: Estimate drag coefficientStep 4: Estimate total drag (D)Step 5: Estimate the thrust produced by the engines at altitude (T)Step 6: Find the rate of climb (dh/dt)

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C ExampleUsing the standard expression to estimate the true mach number of the aircraft at altitude,The true mach number is 0.3267, the speed of sound at 600 meters is 337.96 m/s and the density of air is 1.156 k / m3.

The true airspeed (TAS) is 110.41 m/s or 214.6 knotsUse the fundamental lift equation to estimate the lift coefficient under the known flight condition

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C ExampleThe lift coefficient need for flight is calculatedThe Drag coefficient is computed using the Drag polarCD0 is interpolated from values

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C ExampleThrust is always given with dependencies on Mach number and Altitude Sea level and static thrust is the highest

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C at 8000 m

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C : L/D calculation

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Example

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyR/C Observations R/C is highest at sea level and low Mach number maximum thrust is available Reduces non-linearly with increasing altitude depends on density drop tapers of to zero as it nears the service altitude R/C is also affected by aircraft Weight and Climb speed. Next slide shows the effect of weight on R/C

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyEffect of Weight on R/C

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologyEffect of Temperature on R/C

M. S. Ramaiah University of Applied Sciences#Faculty of Engineering & TechnologySummaryIn this session following topics were discussed:Take off and landing requirements of different types of aircraftTake off performance of an aircraftBalanced field length requirements for aircraft take offLanding performance of an aircraftClimb performance of an aircraftM. S. Ramaiah University of Applied Sciences#Faculty of Engineering & Technology