Question

AERODYNAMICS

5- What is the effect of a headwind which is 20% of the landing speed on a landing distance?

6- What is the effect of a tailwind which is 20% of the landing speed on a landing distance?

7- Consider the case of two airplanes of the same type and c.g. position but of different gross weights. The use of the maximum coefficient of braking friction will bring both airplanes to a stop in the same distance. As a result, both airplanes would have identical acceleration and identical stop distances from a given velocity. What is the principal difference between the two airplanes as they reach a stop?

8- In the prediction of takeoff distance from the handbook data. What are the primary considerations must be given for Reciprocating powered airplane and Turbine powered aircraft?

Answer 1

5- A 39% decrease in landing length occurs at a headwing which is 20% of the landing speed.

6- A 47% increase in landing distance occurs at a tailwing which is 20% if the landing speed.

7-The heavier airplane would have a greater kinetic energy to be dissipated by the brakes and the principal difference between the two airplanes as they reach a stop would be that the heavier airplane would have the hotter brakes.

8- Primary considerations for Reciprocating powered airplane are:

• Pressure altitude and temperature - to define the effect of density altitude on distance.
• Gross weight - a large effect on distance.
• Specific humidity - to correct cakeoff distance for the power loss associated with water vapor.
• Wind - a large effect due to the wind or wind component along the runway.

Primary considerations for Turbine powered airplane are:

• Pressure altitude and temperature - to define the effect of density altitude.
• Gross weight.
• Temperature - an additional correction for nonstandard temperatures to account for the thrust loss associated with high compressor inlet air temperature. For this correction the ambient temperature at the runway conditions is appropriate rather than the ambient temperature at some distant location.
• Wind.

In addition, corrections are necessary to account for runway slope, engine power deficiencies, etc.