Re: DC10 / MD11 Gear

Date:         16 Sep 97 02:35:27 
From:         stevec00@juno.com (Joel S Cole)
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Quoting "john r." <john@guava.demon.co.uk> Mon Sep 15 10:01:42 1997
>I was once told that the DC10 airfrane was much harder on its tyres and
>undercarriage due to the fact that on takeoff very little lift is
>generated by the wings untill rotation. I think it was only 10 - 15% of
>the weight transfered.
>Compared with the 747 and L1011 which had values more like 30%.
>Sitting in a 747 you can watch the wings rise a lot befor rotation.
>
>Could this explain the many landing and t/off incidents of the DC10 /
>MD11.
>Does anyone have any facts ?

	Having operated B747s, DC10's and MD11's at one time, FedEx has
some experience with tire wear on these.  It is hard to correlate the
wear with a/c type, as each operate with different tire sizes &
manufacture as well as different loads.  After many studies of the causes
of tire wear, the #1 cause is scuffing during sharp taxi turns followed
by #2 touchdown.  I doubt Takeoff is much of a factor unless the time
required to reach Vr is significantly larger.
	Same goes with Landing Gear(i.e. undercarriage).  How do you
"compare wear" between a/c with different TOGW, different number of
struts and wheels.  The purpose of the FAR's is to design the aircraft to
be able to withstand the same loads.  Many gear parts have Safe Life
Limits which is an indication of the margin of safety built into the
design.
	And I would think the wing deflection would depend on the length
and stiffness of the wing, which is different between the two a/c types.
I would guess the wing deflects differently between the B747-200 and the
new wing of the B747-400.
	Maybe I missed the intent of the question.

     		STeve Cole~

  Anyone have info of a DC10 incident somewhere in Europe in 1976(?)
where aircraft rolled over on landing?