Mailing List lml@lancaironline.net Message #17026
From: <Sky2high@aol.com>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: [LML] Front oleo castering
Date: Sun, 05 Jan 2003 21:46:30 -0500
To: <lml>
In a message dated 1/5/2003 5:57:30 PM Central Standard Time, ian.crowe@sympatico.ca writes:

I have had my front oleo rebuilt by Lancair and it appears that it has excessive "Stiction"  that is a combination of inherent stickiness and friction.


Ian,

For a while, Lancair was experimenting with 30 weight fork oil instead of the usual 20 wt.  I had to go back to the 20 wt. because the 30 wt became very stiff in the cold weather.

<I am inclined to think that the situation should be avoided by better handling of the side to side fuel consumption.>

Consider that a 200 pound pilot with his belt buckle at BL18 provides a moment of 3600 inch pounds whilst fuel being used from a full wing tank out at about BL110 is equivalent to about 5 gallons of fuel (3600/110=32 pounds).  If you don't have a system that draws evenly from both wings, assuming starting with full tanks and flying solo, draw the first 10 gallons from the left tank and then 5 from the right, 5 from the left etc.

Assume that 17 gallons of  fuel fills the wing from BL50 to BL115 and that the use of 3 gallons moves the "CG" in about 10 inches.  So, for a wing:
060x18=1080
070x18=1260
080x18=1440
090x18=1620
100x18=1800
110x12=1320
----------------------
             8520  moment
And a 1/4 tank would have a moment of about 1500.

pilot and left wing - 1/4 right wing = 3600 + 8520 - 1500 = 10620

Say the aileron lift is at BL125, then 10620/125=85 pounds of lift needed at the aileron.

Scott Krueger
N92EX


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