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The internal bracing is badly designed.  The bracing wires attack the spars at their weakest end where there is no strut or compression rib to take the resultant stress.  It is obvious that this faulty arrangement leads to spar deflections at the points where the lugs are attached.  These deflections at were often of the magnitude of 6 mm. and more.

As this result was discovered at the overhaul when the spars were already deformed, it could not be remedied by simply fitting a strut or compression rib.  Therefore a thick three-ply panel reinforced by two triangular glued struts was fixed between the spares at this place.

The designer of the machine proffered the opinion that this internal bracing is not needed as a drift truss, because the wing is strong enough without it, but that it serves more to keep the spars in place during assembling, an assertion which must be taken "cum grano salis".

Though there are no real compression ribs in the drag truss, still there are some double extra strong ribs, intended to serve as compression ribs.

That a better drift is needed is shown also in

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