Mailing List lml@lancaironline.net Message #62200
From: <rwolf99@aol.com>
Sender: <marv@lancaironline.net>
Subject: Single Seat Lancair 320 Flight Controls
Date: Thu, 31 May 2012 15:17:31 -0400
To: <lml@lancaironline.net>
Jeffrey -
 
It would not be too difficult to adapt a 320/360 to a single seat.  "All you gotta do is..." 
 
1)  You need to move the forward elevator pushrod to the side.  Obviously you can't run it thru your body, and there will not be room under the seat.
 
2)  To accomplish this, you will have to make a new forward weldment to which the control stick attaches.  I would use the same attach points to the front spar.  Extend the new weldment to one side and attach the forward elevator pushrod to that end.  You will have to have the same distance between the pushrod attach point and the axis of rotation.  (Duplicate the tabs which are presently at the center of the weldment at the new attach point at the end.)  Have the stick pivot at the same distance from the axis of rotation also.  This is not a good explanation, but the redesign of this weldment is something you will have to figure out.  One complication -- presently the sticks attach at the ends of the weldment -- now it will attach in the middle -- so some creativity is required.  The key point is to have the distances between the pivot points and the attach points of pushrods identical, so that the handling qualities don't change.  (Note that the existing stops in the aileron system are at the stick.  You will have to provide for this in your new design.)
 
3)  You will need to install longer aileron pushrods from the inner idlers to the stick. 
 
4)  I would not change the hardward aft of the baggage bay, where the present idler and bobweight are located.  You can accomplish this by installing an idler to the forward face of the baggage bulkhead.  I have attached a crude sketch of such an arrangement.  This will be much simpler than the forward weldment, as it simply translates the fore-aft pushrod motion back to the vehicle centerline.  You should probably install a phenolic hard point where these loads are applied to the baggage bulkhead.
 
5)  Make a short pushrod to connect this idler to the existing idler/bobweight contraption aft of the bagage bulkhead.
 
Once you get this all built, do a structural integrity test to make sure the pitch control structure is robust.  Apply full aft stick and then increase the applied force to 167 pounds (FAR 23.397) and make sure it holds together.  Do the same with forward stick.  For ailerons, use 67 pounds.  Look for things like aileron pushrod bowing and front weldment bending.  Oh, and disbonding of the structure from the baggage bulkhead.
 
My drawing does not show the pushrod displace all the way to the side of the vehicle.  If you do that, it will not align with the vehicle centerline.  However, I think it will be okay if you do that.
 
I don't get the feeling that this is a huge undertaking.  I'm not sure why you'd want to do it, but as long as the distances between the appropriate pivot points are maintained, you should do fine.
 
Enjoy!
 
- Rob Wolf
 
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