Sender: "Marvin Kaye" <marv@lancaironline.net>
To: lml@lancaironline.net
Date: Sat, 13 Nov 2004 16:24:30 -0500
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From: "Dan Schaefer" <dfs155@adelphia.net>
Subject: Engine Runups
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Charlie K. wrote:

<<Just a(nother)  word of warning-- if the ropes are tied to the landing
gear
by the tire area--an extreme amount of stress is placed on the main landing
gear actuator and --if hydraulic pressure is not available (ie circuit
breaker pulled) -- the lock pin that holds the landing gear in the down
position can/will be sheared.>>

Hmmm! Interesting. IMHO (and speaking from the perspective of about 40+
years in the aerospace industry) landing gears are (should be) designed to
withstand the largest loads in the aft and vertical directions, which are
seen during landing. Don't know if anyone has ever instrumented a Lancair's
gear to find out, but I'd bet that the aft directed loads developed even in
a squeaker landing is higher than most imagine. (Not to mention the vertical
loads seen resulting from the too often observed perfect landing two feet
above the runway)! Additionally, designers must take into account that
airplanes often land slightly (or worse) sideways so the gear must be able
to withstand those loads as well.

If you can fail ANY part of your main gears from the static thrust of your
engine alone, almost all of which will be imposed on the gear in the aft
direction, when the airpane is restrained by chocks or ropes (or whatever),
the airplane is not safe to land.

And lastly, in the aircraft pictured, I can't believe that the gear
actuators react any of the primary fore and/or aft loads.

Dan Schaefer