Calculating landing distance for Flight

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Discussion Overview

The discussion revolves around calculating the landing distance of an aircraft, considering various parameters such as approach speed, descent angle, load factor, and deceleration upon touchdown. The scope includes homework-related calculations and the application of physics principles to solve the problem.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant presents the problem statement and relevant equations for calculating landing distance, including approach distance, flare distance, and ground roll.
  • Another participant suggests using the work-energy equation for ground roll calculations, noting the importance of mass in the context of force.
  • A third participant argues that for ground roll, the initial horizontal velocity and deceleration are sufficient, indicating that mass does not affect the calculation when neglecting air resistance.
  • A later reply acknowledges this perspective, indicating a realization that the problem simplifies to a force equation.

Areas of Agreement / Disagreement

Participants generally agree on the approach to the problem, but there is some initial confusion regarding the role of mass in the ground roll calculation. The discussion reflects a refinement of understanding rather than a consensus on a single method.

Contextual Notes

There is a lack of clarity regarding the assumptions made about air resistance and the specific conditions under which the calculations are valid. The dependence on mass in the ground roll equation is also highlighted as a point of contention.

Who May Find This Useful

This discussion may be useful for students and practitioners interested in aerodynamics, aircraft landing dynamics, and the application of physics in engineering contexts.

praveenpandiyan
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Homework Statement


An a/c has an approach speed of45 m/s with descent angle of 7.1 deg. if the a/c load factor is 1.2 and constant deceleration at touch down is .25g (g=9.81).its total landing distance approx over a 15m high obstacle is

Homework Equations



R=v/g(n-1)
Sa=(h-hf)/tan( teta)
Sf=Rsin(teta)
hf=R(1-cos(teta)
Sg=v2m/(2*F)
R-radius,hf-flare height,Sa-approach dist,Sf-flare distance,Sg-ground roll
S=Sa+Sf+Sg

The Attempt at a Solution


well i have found value for approach and flare distance.but for ground roll I am lacking mass to consider for calculation or do i miss smeting?.. any suggestion wld be helpfull.[/B]
 
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praveenpandiyan said:

Homework Statement


An a/c has an approach speed of45 m/s with descent angle of 7.1 deg. if the a/c load factor is 1.2 and constant deceleration at touch down is .25g (g=9.81).its total landing distance approx over a 15m high obstacle is

Homework Equations



R=v/g(n-1)
Sa=(h-hf)/tan( teta)
Sf=Rsin(teta)
hf=R(1-cos(teta)
Sg=v2m/(2*F)
R-radius,hf-flare height,Sa-approach dist,Sf-flare distance,Sg-ground roll
S=Sa+Sf+Sg

The Attempt at a Solution


well i have found value for approach and flare distance.but for ground roll I am lacking mass to consider for calculation or do i miss smeting?.. any suggestion wld be helpfull.[/B]
in your work-energy equation for Sg, m/F per Newton 2 is given! Or use the kinematic equations instead.
 
You have an initial horizontal velocity at touchdown and the deceleration. That's enough. For ground roll, and leaving aside air resistance, mass doesn't matter.
 
yeah.i see it now,its a simple force eqn. thanks all
 

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