Main Gear Legs, Rounded Edges

·         Wayne Eckertson

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I would like to round the edges of landing gear legs for aesthetic reasons. I would like to sand off the edges of the gear legs to create a full bullnose finish. (See attached JPG.) Are there any limitations or recommendations in doing this? I am building my J230 under the US E/AB so certification limitations do not apply.

Wayne

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·         Doug Smith

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Hi Wayne,

The gear legs are subject to a fairly complex loading, with the main loads being bending and torque. The change you're describing will reduce the cross sectional area of the leg (important for torque stiffness) by a couple of percent and the moment of area (important for bending strength) by about 3.5% (assuming you only do it on the leading edge: double those figures if you plan on doing it on both ends). Depending on your aircraft and how you use it that might or might not be significant... (will it be 1543lb MTOW [700kg] or less? Used on rough/short strips or long glassy ones? Greaser landings every time or the occasional runway-denter?) So I guess it's up to you if you're happy with that sort of change :-).

If you decide to go ahead make sure you blend the change from square to rounded out over a few inches - I'd want at least a 5:1 taper ratio. That will minimise stress concentration due to the change in section. Also make sure you wear proper protective gear when you do it - most importantly a proper mask (not just a paper dust mask) - fibreglass dust isn't nice.

Best Regards,
Doug.