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Date: Mon, 15 Jun 2009 13:45:55 -0400
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From: "Robert Pastusek" <rpastusek@htii.com>
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Subject: RE: [LML] IV (-P) Aileron Crossover Tube
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Bill Wade wrote: 

 I'm trying to set up the joystick torque tubes- I have the type where the 
forward arms are oriented down, not up as shown in the Manual. Setting up 
the 10 degree slope called for means that the aileron crossover tube won't 
clear the nose wheel housing. It seems plain that the forward torque tube 
bearings have to be raised enough for it to clear.

 My question is: what's a good height for the crossover tube? If it just 
clears the housing it seems it'll be below the lower edge of the instrument 
panel. In that position could someone's leg hit it? If it was set higher 
could it interfere with engine and prop control placement? My instinct is to

have it just above the bottom of the instrument panel but I'd like to know 
what has worked for other builders.


Bill,
I'd recommend you move the mounting brackets for the forward ends of the
aileron torque tubes up just enough to allow the cross-over tube to clear
the top of the nose wheel well. 1/4" of clearance is enough; perhaps 3/8" if
you're concerned. The crossover tube moves up vertically when you move the
ailerons, so the neutral stick position is the closest the crossover tube
will come to the nose gear tunnel. It won't matter that the crossover tube
is slightly below the bottom of the instrument panel, and you'll thank
yourself a hundred times for the space when you start installing avionics
and wiring.

No way will your legs/knees be able to touch the cross over tube--give it a
sit test to note that you can't extend your legs/knees completely
horizontally...you probably can't even touch it without picking your feet up
off the fuselage floor.

Do pay attention to where the throttle/mixture/pitch controls run in this
area...especially if you're changing the control configuration/location at
all, as these controls extend straight behind the panel for several inches,
and must be kept well clear of the crossover tube--allowing space for the
tube to move vertically as you activate aileron control. 

Last point. When you raise the front mounting point for the aileron torque
tubes, you upset the 90 degree geometry between the aileron torque tubes and
the vertical aileron push rods. Be sure to relocate (tilt) the rear aileron
torque tube mounting frame slightly to maintain the geometry. Basically,
start with where the aileron control tube passes into the fuselage as the
reference point. Move up to the rear aileron torque tube pivot point. Move
this point aft (tilted toward the rear of the fuselage) to generate a 90
degree angle between the (not quite) vertical control rod and the aileron
torque tube. Hold this geometry and "swing" the forward end of the torque
tube to the position you established based on crossover tube spacing. (It's
harder to write than to do, and it doesn't have to be perfect. The spherical
bearings will allow a couple of degrees of mis-alignment, but the closer you
can get to a 90 degree angle between the torque tube and the vertical push
rod, the better. Write or call if questions on this.

Bob Pastusek