Agreed, on all points, and especially on the manual's pretense regarding
flexing of the gear leg, which seems a bit unlikely. Not knowing either the
force to stretch the bungee enough to load the 2.5mm (3/32 inch) diameter
safety cable, or the cable's tensile strength (and not having the nose gear
leg handy to make measurements) I'll make a guess that the breaking force
for a single length of the cable is 1200lbs and the pivot point on the gear
leg is located at around 1/4 of the overall length (for a 3:1 mechanical
advantage), which computes to 1600lbs at the wheel to break the cable with
none of the load taken by the bungee (for a load shared by four parallel
cables - but the calculated value is an approximation because it is actually
a single cable wrapped over the assembly). I'll go out on a limb here
(because I'd rather guess than calculate) and say that a mere 1600lbs is not
going to flex that beefy gear leg by much, and definitely not enough for the
eye to perceive. Later I'll get out my (ancient) Mechanics of Materials
textbook and do the calculation for the deflection of the gear leg under
load.
Now that I see how little it takes to break the safety cable it makes me
wonder why the nose heavy Europa has a steel assembly instead of one
fabricated from aluminum.
Best regards,
Rob Housman
A070
-----Original Message-----
From: owner-europa@post.aviators.net
Subject: RE: Trike Nose Leg Bungee Breaking.
Hi! Rob.
IMHO The main item to protect is the propeller and its attendant parent
attaching point !
In my case thank the Lord for the safety strap/cable. IMHO I would like to
know the load at which the nose leg tube provides "flexing" ? and then next
I would like to know its yield load? Having bent mine DOWN with a
"wheelbarrow" bounced landing! All these questions because I don't believe
the theory that the leg is ACTUALLY providing sufficient "FLEXING" on its
own even with moderately heavy landings.
When a) and b) bounced it , it was with such force that the TAIL of the nose
wheel spat got a bash and also gravel rash from the runway ! { a) and b)
shall remain nameless! But that's where I believe the rot started with my
bungee}
Regards
Bob Harrison G-PTAG
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