Gear Load Factor (Reaction Load) Question

  • Thread starter Richtdow
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  • #1
Richtdow
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TL;DR Summary
Why does an increase in gear load factor decrease shock stroke?
Using the equation to determine shock stroke I input a gear load factor. For the aircraft landing gear that I am designing, I am assuming a gear load factor of 5 which is what is generally used for Navy fighter aircraft. This is because I am designing landing gear for a STOL aircraft and I want it to be able to drop right onto the landing spot more like a carrier landing. The question I have is why does an increase in gear load factor decrease the shock stroke? Perhaps I don't understand the concept of gear load factor very well, but I would assume that a harder landing would demand a greater shock stroke.
 

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  • #2
jrmichler
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Aircraft landing gear design starts with an assumed vertical velocity component. The landing gear absorbs that vertical velocity component by compressing the shock strut. The load on the airframe depends on how fast that vertical velocity is reduced to zero. If the landing gear has long struts with soft springs and low damping, the force is low while the compression distance is long. If the landing gear is rigid, with no compression distance, then the force is very high and things get broken.

Your analysis is turning that around by starting with the allowable load factor, and using that to find the required shock strut compression distance. A low load factor requires a long stroke to gradually decelerate the vertical velocity component. A high load factor stops the vertical component faster, so needs less distance.
 
  • #3
Richtdow
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That makes sense and thank you. It looks like taking into consideration the time necessary to decelerate the vertical component to zero is a factor that I was overlooking.
 

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