# Landing Gear – Rational Spin-Up and Spring-Back Loads

June 18, 2016

There is a relatively simple method in the FAR part 23 appendix for calculating rational landing gear spin-up and spring-back loads. This method is referenced to and better explained in NACA-TN-863 which also has some other very interesting and useful data.

This Spreadsheet has a method for calculating the rational horizontal loads for the part 23 basket of cases. Note that the  braked roll horizontal loads is calculated using the arbitrary 0.8 coefficient of friction from the regulations.

This method can provide a significant load saving and weight saving over the simple method. However! As always there are caveats; this method assumes that the aircraft is landing on a well prepared runway, therefore the loads generated by the method are likely to under-predict loads for rough field landings.  If you are designing an aircraft intended for rough field use it is recommended that a rational approach is used to assess the load generated by rough ground or that the arbitrary horizontal loads from the regulation are used.

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### 2 Comments on "Landing Gear – Rational Spin-Up and Spring-Back Loads"

• could you please explain how the Fvmax is computed in your app? what did you assume for nj and We?

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