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Re: Europa-List: Stabilizing the airframe when on the monowheel trailer

Subject: Re: Europa-List: Stabilizing the airframe when on the monowheel trailer
From: Sidsel & Svein Johnsen <sidsel.svein@oslo.online.no>
Date: Wed, 26 Jan 2005 21:04:13

There is another point that should be addressed:

One should be very careful when locking the airframe, or the wings, to a 
trailer.  If you lock it by the drag pin sockets, or wing pins, or at any 
other two or more stiff points spread across or along the fuselage, you must 
consider that the trailer is not infinitely rigid.  You wish to prevent the 
aircraft from moving about, but you do not want to use the aircraft to 
prevent the trailer from twisting and bending as it moves along, and 
especially as it hits the bumps.  A flat-bed trailer, or an open-frame 
trailer like the standard mono-wheel trailer, does not have too good torsion 
stiffness.  An enclosed trailer with metal walls and roof is stiffer, but I 
would still not trust it to never excert an uneven force on the aircraft.

I have a covered trailer for my tri-gear (built by David Schofield).  The 
aircraft will be secured by shaped clamps over the two main wheels, and a 
strap from a u-bolt under the tail to prevent it from ducking.  A tri is of 
course easy to secure.

The wings are carried along each side wall.  To avoid the problem described 
above (the wing adding stiffness to the wall), the wing is held against the 
wall in only one place, at its CG, by a yoke-like clamp going cordwise.  At 
this same section of the wing, it rests against a shaped support on the wall 
side of the wing.  The forces from the support and the yoke is taken only in 
way of the spar and the close-out section at the trailing edge of the wing). 
The weight of the wing is carried only at the ends - under the spar root 
(where there is also lateral suppor) and at the leading edge close to the 
tip (flat support, hinged to ensure that it always lies dead flat under the 
leading edge.  No side support here.  Cushioned, of course).

Regards,
Svein
A225 - XS Trigear - now in Norway 




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