There are many variables which affect the touchdown shock level of an aircraft. These include:
- Descent or sink rate
- Forward and side velocities
- Roll, pitch, and yaw angles and corresponding rates
- Weight and center of gravity
- Cross wind, wind shear, gusts, etc.
- Runway contact loads
- Aircraft landing gear design
- Structural dynamics of the aircraft and launch vehicle system
The aircraft’s kinetic energy at touchdown is dissipated by the landing gear, primarily by the struts. Each strut is filled with oil that is forced at a controlled rate through an orifice as the strut is compressed on touchdown. An efficient landing gear design thus reduces the loads transmitted into the airframe during landing.
* * *
A portion of the aircraft landing shock analysis can be performed using the surface roughness from San Francisco Runway 28R. The runway has since been resufaced, but the historical data may still be used for conservatism.
The data is given in terms of Runway Length(ft) & Elevation(ft).
The original measured data is given at SF28R.txt
The data with the severed bump modification (smoothing) is given in: SF28R_severe_bump.txt
* * *
Federal Aviation Administration, FAR Part 25, Airworthy Standards: Transport Category Airplanes, Subpart C, Section 25.473.
* * *
– Tom Irvine