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.....................RESTORATION OF SCHWEIZER 1-26A, SERIAL #026

................................................................(Click on the image to view the larger version.)





These are all the parts it takes to put the fuselage back together again other than the frame.  At this point I hadn't taken the fabric off the wings yet so the few moving parts in them are not included here.  The top image starts at the bottom with the spacers from the canopy frame then moves up to the nose area faring pieces that give the fabric covering a smoother shape.   Next are the tow release, spoiler and elevator trim cables along with a tub of miscellaneous pulleys and other small parts.  There are many bags of nuts, bolts and the parts they attach.  The long tube at the left is the control stick torque tube that will connect to the elevator and ailerons. At the top you can see the chromed control stick, nose bulkhead, rudder pedals and all the tubing that provide the fairing for the fabric around the cockpit and nose areas.  The bottom image includes the instruments, push rods, brackets, control horns, rear fuselage stringer attachments and, the nose and tail cones.  Some of the parts have already been cleaned and given a prime coat to prevent rusting until the final epoxy based primer was sprayed to seal everything up.





The starting point once everything was removed for refurbishment was building a new set of canopy rails.  Normally these would be an extension of the cockpit belly pan, but the crash this sailplane experienced in the early 1960s destroyed this area so my father simply made substitute rails out of angle aluminum.  Over the years these had become very corroded and needed to be replaced.  The old ones were used as templates to locate the holes where they are cherry riveted to the main longerons.  This was very time consuming and required a lot of planning to make sure they fit properly so the canopy would line up with the cockpit turtle deck area right behind it. The left rail (right side of image) is the hinge attachment side since the pilot enters the cockpit from the right side of the aircraft.  The black spaces in the other rail are where the latching fixtures are installed.  The wing carry-thru was also temporarily bolted in for the wing fitting and alignment of some other control system parts.




This is an example of fitting the cockpit turtle deck rail to the angled piece that integrates it into the cockpit rail.  Again, this is a critical joint since it must match the canopy framework, which was also going to get an extensive work over (see below).  You can see some of the corrosion on the original rails in the lower right corner of the image.  Eventually, after a lot of trial fittings, the angled piece got drilled but not riveted to the rail.  The final installation would have to wait until the finished rail was riveted to the longeron since they required the cherry rivets, whereas the angle could be installed with regular rivets. This was a good example of the need to work slowly and plan many steps ahead in order to eliminate having to back track by taking out rivets that creates its own problems.





The top image is the aft fuselage turtle deck stringers with the bulkheads temporarily bolted to the fittings so everything can be glued up.  The holes below each stringer were meant for string that would go through slots in the stringer to hold them in place while the glue dried.  We decided to use pins to hold the stringers in position while the epoxy setup and this worked well.  The bottom image shows a much larger fairing piece made out of 1/64 th  plywood from the local hobby shop.  You can see the difference from the original rebuild picture in the previous section.  It came to me with a black plastic material as the fairing, but we found Poly Tak would melt this particular type of plastic so wood was the best choice from an attachment (gluing) standpoint to the stringers and later for the fabric covering.  The whole thing was then taken off the fuselage and given a good coat of aircraft grade varnish that will stand up to the Poly Tak's MEK based solvents.  I learned quickly to always do test samples where dissimilar items are coming together to make sure they are compatible.

 




The top image is the latching side of the canopy frame.  It looks very messy and in fact had significant rusting so it and the other main canopy frame rails had to be replaced.  I also replaced the long tube that holds the parts that actually go into the brackets build into the fuselage rails shown above.  This was easier than trying to clean the corrosion and rust out of the original one.  I was lucky to have a great metal works shop in the hangar next door and they made quick work of the elongated holes that contain the latch mechanisms handles.  This new tube eventually got brazed onto the new frame piece just as it is shown on the drawings.   The bottom image is the other side of the canopy where the hinges are attached to the frame.  They were corroded and the steel tube also rusted beyond saving.





This is how I went about fixing the problem.  The jig was build on a solid foundation using the original canopy frame since it must have fit the fuselage rails in the past.  They may be hard to see but there are a number of small "L" shaped brackets along both sides of each frame piece to hold the new square tubing in exactly the same position for welding.  The wood pieces on each end hold it down against the table, which is a $3 piece of scrap from the Home Depot aircraft supply store and placed across saw horses.  The vertical pieces were designed to hold the hoops at the proper angle to match the front instrument panel bulkhead and the rear turtle deck bulkhead framing.  This is all done before the old frame pieces are cut off the hoops.  You can see the latch tube has been cut off at this point since it was attached to the bottom of the right frame and would have made it impossible to build the jig.  You can also see the new latch tubing and the new square frame tubing that will be installed.





The main concern when cutting the hoops off the rails was retaining the proper height of the front and rear hoops since they had to match the cockpit turtle deck that didn't need any rebuilding.  The metal shop owner said to put a mark on the hoop about an inch up from the rail then measure the distance from the mark to the rail to establish a base line value for each corner.  Then cut off the hoops vertically through the rail on either side of the joint instead of trying to cut it flush with the rail with a cut off disk.  Now you just grind off the excess rail material until the end of the hoop tube is the base line distance from the mark.  I wrote these numbers down on the jig so they were always available during the grinding and measuring.  The expert welder in the shop then reattached the hoops to the new rails and you can see the canopy fairing and old canopy fit very nicely.  Again, this was all very time consuming and I was lucky to have people next door to assist.





This image is a little deceiving since it looks like a rudder cable is going around a corner.  I merged two images to show what the two cable guides looked like from the same angles on each side.  They are Teflon versus wood but you can see they are constructed differently.  I think what happened was dad ran out of enough large pieces to cut out the one on the right so it matched the left.  He stacked some smaller pieces together to make up the bottom of the right guide as can be seen from the screw head along the bottom edge.  The problem was resolved by picking up a scarp piece of Teflon from a local plastics distributor that had some holes in just the right places.  I cut some slots and trimmed a little here and there to come up with one that matched the left image.  These shots also show the installation of the arm rests and the oxygen regulator mounting.  I have put a flat plate on the mount and Velcroed a Mountain High oxygen controller on it to save space for my knees.




Now that all the black primer has been removed from the nose cone bulkhead I have started fitting the elevator trim cabling.  The fuselage is upside down at this point so for the experts it really isn't mounted backwards.  I found I could make good use of adele clamps to help hold the cable housing in place and the one on the mounting bracket (bottom image) allowed for an improved angle that freed up the cable movement.  The black vertical piece is the shield for the tow release cable that dad installed in place of the original aluminum tube.  He also installed aircraft grade pulleys at the top and bottom of this shield for the release cable to eliminate the friction.  You will see other examples of where he  reduced friction though the use of Teflon or ball bearings in the fuselage and wings.





In this image you can see the cockpit skin being held in position.  The flanged pieces are the base for the seat pan that is held in place with large sheet metal screws into blind nuts.  The other interesting thing here is the bolted on seat belt fasteners that are seen on each end of the black cross member at the right of the image.  The original belt fasteners can be seen built into the framework which can be seen as the gusset type piece in the lower right corner.  It appears the purpose of the bolt-on "kit" is to move the attachment point further forward so the belt goes around your waist at a better and more comfortable angle.  While they were part of the final installation I found the belt make that I used (Hooker) worked better for me using the original factory locations.  The cables running along the bottom are for the elevator and the large pulley in the bottom right is for the wheel brake cable. Holes and flange in the bottom are for the skid bolts.



This is a shot of the elevator bell crack in the aft fuselage.  The only thing unusual here is that the rotation point has been changed from a bolt inside tube to a ball bearing unit.  My father had access to a large aircraft factory salvage yard so these were easy to come by at the time.  This is just one of the points where he used ball bearings to help decrease the control system drag  and reduce the flying effort over long periods airborne.  The log book has a number of flights over 10-hours and some over 11 by Harry so this became important.





There are couple of things going on here.  At the base of the vertical fin you can see the aluminum fairing used to transition the fabric off the fin onto the fuselage where the rudder cables will eventually come out.  The front of the fairing comes together at the front by wrapping around the leading edge up and bolting to the end of the center stringer.  On the fin spar down inside the fuselage you can see the Teflon fair guides for the elevator cables, again to reduce any friction and minimize wear on the cable.  At the bottom of the picture you can see one of the side stringer attachment brackets held on to the vertical tubing with adele clamps.  These all needed to be stripped and repainted with epoxy based primer to prevent any corrosion in the future.  The point here was to make sure everything that was under the fabric was given substantial protection since it probably wouldn't be seen again for 10-15 year, depending on how much time the glider spent outside in the elements.




This was the bulkhead in the nose section used for holding the variometer vacuum bottles and the routing of pitot/static lines from the nose cone.  You can see a little bit of corrosion under the Vent label so the panel had to be replaced using the exiting tubing.  We weren't really sure how the bottles were held in place other than the neck went through the hole and the lid screwed back on.  However, there was no obvious point of attachment to hold the bottom of the bottle in a horizontal position so an entirely different method was designed that will be seen later. At the bottom of the picture you can see the old style rudder pedals.  You can also see the elevator bell crank and cables going aft.  The gray tube from the bell crank is the actuator that goes to the control stick.



The nose fairing tubes have been temporarily installed to confirm their locations.  Harry labeled them and drew a diagram of the mounting order, along with most of the other fairing tubes, so this part went quickly.  You can also see the spoiler cable running through pulleys on the left side of the image and the tow release cable and pulleys in the center.  Dad added pulleys for the tow release instead of having the cable go through a semi-circular tube to make the turn to the release arm. 




The top image shows the bottom of the nose section where the fairing tubes are attached to the front of the cockpit skin.  You can see the added short tubes used to smooth out the transition when the fabric goes onto or leaves the belly pan so it doesn't have a depression that causes drag.  The bottom image is the rear part of the cockpit skin showing some of the shorter tubes that take out the fabric depression that mainly just make it look good.




The initial rebuild is nearing completion.  The fuselage has almost all the parts installed to see how everything fits.  The canopy isn't on due to the C-clamps helping to hold the cockpit skin in place so the clekos don't pop out and hit something like the 180 right next to it.  That is how much tension is created by the curvature of the skin.  At this point you can see there are actually 9 upper nose fairing tubes, one extra tube along the sides and the flaring pieces at the nose cone and instrument bulkheads.  Dad was always tinkering with things so when he rebuilt the nose section he re-spaced the fairing tubes to give a little more round shape to the nose.  I don't recall if dad built the nose fairings or if that is something Harry added during a recovering periiod.  You can also see the back side of the instrument panel that Harry built so he could install some other items that he felt aided in winning contests.  Notice the wood block on the roll over structure.  It is a little taller since dad added about 3/4" to the height to help with clearnce over my head.



Here are the seat and floor pans laid into the cockpit area to check for fit and give it a little more finished look.  This will eventually all get stripped primed and painted before final installation.  The seat pan gets attached to the red pieces you saw in a previous picture of the cockpit skin with large PK screws into blind nuts.  The boot in this picture is a canvas material but will get redone in maroon leather as will the arm rests.



Updated 8/13/12
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