File Size2.12 MB
Tags   Impact     Landing Gears     NACA     Technical Notes  
naca-tn-2596 An Impulse Momentum Method for Calculating Landing Gear Contact Conditions in Eccentric Landings.pdfDownload 

National Advisory Committee for Aeronautics, Technical Notes - An Impulse Momentum Method for Calculating Landing Gear Contact Conditions in Eccentric Landings

An impulse-momentum method for determining impact conditions for
landing gears in eccentric landings is presented. The analysis is pri-
marily concerned with the determination of contact velocities for
impacts subsequent to initial touchdown in eccentric landings and with
the determination of the effective mass acting on each landing gear.
These parameters determine the energy-absorption requirements for the
landing gear and, in'conjunction with the particular characteristics of
the landing gear, govern the magnitude of the ground loads.

Changes in airplane angular and linear velocities and the magnitude
of landing—gear vertical, drag, and side impulses resulting from a
landing impact are determined by means of impulse—momentum relation-
ships without the necessity for considering detailed force—time varia-
tions. The effective mass acting on each gear is also determined from
the calculated landing—gear impulses. General equations applicable to
any type of eccentric landing are written and solutions are obtained
for the particular cases of an impact on one gear, a simultaneous finpact
on any two gears, and a symmetrical impact. In addition a solution is
presented for a simplified two-degree- of- freedom system which allows
rapid qualitative evaluation of the effects of certain principal

The general analysis permits evaluation of the importance of such
initial conditions at ground contact as vertical, horizontal, and side
drift velocities, wing lift, roll and pitch angles, and rolling and
pitching velocities, as well as the effects of such factors as landing-
gear location, airplane inertia, landing-gear length, energy-absorption
efficiency, and wheel angular inertia on the severity of landing
impacts. A brief supplementary study which permits a limited evalua-
tion of variable aerodynamic effects neglected in the analysis is pre-
sented in the appendix.

Application of the analysis indicates that landing-gear impacts in
eccentric landings can be appreciably more severe than impacts in
symmetrical landings with the same sinking speed. The results also
indicate the effects of landing—gear location, airplane inertia, initial
wing lift, side drift velocity, attitude, and initial rolling velocity
on the severity of both initial and subsequent landing-gear impacts.

A comparison of the severity of impacts on auxiliary gears for tricycle
and quadricycle configurations is also presented.

Have A Comment On This Article? Post It Here.

Comments are moderated and will not be published until approved. Your email address will be kept confidential. Please review our Comment Policy before posting your comment.


Microsoft Excel Spreadsheets

FREE ANALYSIS SPREADSHEETS 3 Over the last 10 years we have developed hundreds of spreadsheet tools to help us with our structural analysis work. We have made these available through the Abbott Aerospace web site and the XL Viking project. We have now brought them into the technical library. They have been updated, improved and the collection has been expanded to cover more analysis methods than ever before.

The XL-Viking Add-In for Excel

XL-Viking 2 We created the XL-Viking Excel add-in to satisfy our own need to make Excel a better engineering tool. XL-Viking shows your Excel Formula in a way that makes sense and brings essential new functionality to Microsoft Excel by providing an additional user interface and easy to use functions.

The Indispensable Tool For Engineers, Mathematicians, Scientists, Accountants and Teaching Professionals!


Technical Papers & Reports

This is our collection of public domain references. All of the material we make available has been placed in the public domain by the authors/owners. If you believe this is not the case and any of the library material is not in the public domain please let us know. If you have any reference material that you would like to see included in the library we would love to hear from you.

Market Analysis and Market Information

Our newest addition to the library is an on-going series of articles on the aircraft and aerospace market. These are part quantitative and part qualitative and introduce a new aspect to the competencies within Abbott Aerospace.