Obstacles, Flaps And Ground Effect

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Obstacles, Flaps And Ground Effect

• Linday GreenSuperiorlabs.inc

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Table of Content

• Take-off Landing Phase of aircraft
• Clearing Obstacles
• Climb Gradient
• Correct Flap Settings
• Reduced AoA
• Slats
• Crosswinds

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Take-off Landing Phase of aircraft

• Most aircraft misadventure happen during the
  take-off and landing phase of the flight.
• Collisions with obstacles during climb out,
  runway overruns on landing occur every now and
  then.
• In this presentation, we introduces some facts
  which helps in the performance of Aircraft in
  this part of the flight.

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Clearing Obstacles

• Advisable to clear any obstacle in your flight
  path by at least 50 ft.
• Check your aircraft climb
• gradient during preflight,
• Information about the
• airports you are going to visit
• on obstacles near the climb
• Out and/or landing path. 
• Check the latest NOTAMs for any new obstructions
  not listed on the charts or in the AIP.

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Climb Gradient

• Calculating the height gain per mile (climb
  gradient) is easy Rate-of-climb (ft/min) /
  Ground Speed (NM/min)
• For example
• 500 ft/min climb and a ground speed of 66 Kts
  (1.1 mile per minute)
•  Dividing 500 ft / 1.1 NM gives a height gain per
  mile of 454 ft / NM.
• This will give you a good indication if you will
  be able to maintain safe terrain and obstacle
  clearance.

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Climb Gradient(contt..)

• Start with a no wind situation for this
  calculation, any headwind component will increase
  the climb gradient to your advantage.

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Correct Flap Settings

• Flaps reduce aircraft stalling speed by
  increasing lift.
•  it enables you to lift-off at a lower airspeed.
• Resulting in a shorter ground run.
• It also reduces the rate of climb (and angle) due
  to a somewhat higher drag.
• You must always use the recommended flap setting
  for the given circumstances.

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Correct Flap Settings (contt..)

• Never, ever reduce a flap setting while in a turn
  or on final.
• In a turn stall speeds are higher and reducing
  flaps could mean a low level stall /
• Extending flaps to the first position usually
  adds quite some lift and a small amount of drag
  spin event.
• the second position will increase both lift and
  drag

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Correct Flap Settings (contt..)

• the third position adds much more drag and almost
  no lift at all.
• The increase in drag helps to stabilize the
  airspeed.

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Reduced AoA

• Keep in mind that with flap extension the wing
  will stall at a lower angle of attack.
• In turbulent conditions a wing drop is more
  likely then.
• Especially so when the flap and ailerons are
  combined,
• E.g. flaperons. Pipistrel aircraft are known for
  this 'feature'.

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Slats

• Slats are leading edge flaps.
• have the effect of increasing AoA, camber, lift
  and wing area thus reducing stall speeds.
• either move forward or are extended from below
  the leading edge automatically or under pilot
  control.

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Crosswinds

• While on approach to a runway with a considerable
  amount of crosswind, it is wise not to use full
  flaps on some type of aircraft without proper
  training from a qualified instructor.
• On these aircraft the full flap setting does not
  lower stall very much, but they increase drag
  enormously. 
• The glide angle will be very steep.
• need to add power to reduce the flight path
  angle. 
• Do maintain power until touchdown, especially so
  in crosswinds.

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Crosswinds(contt..)

• With flaps extended your groundspeed is even
  lower and the effects of the crosswind will be
  that much higher.
• Make sure enough runway is available, else you
  need to change to a more favorable runway or
  divert to another airport.

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