2nd November 2008 - Back Underway

Finally I got the chance to get back into the workshop for a few minutes. First job was to refit the aluminium section that closes the gap between the combing and the firewall round the recently installed windscreen central support and the windscreen tabs. Jobs like this take significant amounts of time but don't seem to move the project forward much. Tuesday I should be collecting the fuel tank from the aluminium welder so next job was to prepare for the installation of the straps that will support the tank. The tank end blank was secured into position to provide the positioning.

20th October 2008 - Windscreen mounts, tabs 161-194

I bought some more Argon this morning, so first job was to complete the weld across the back of the channel that will support the rear of the windscreen. This and the channel on top of the rear spar carry through were then drilled for screws to fasten the aluminium panel which will close the gap between the windscreen and the top fabric. This will sit on a neoprene seal to ensure that the joint is watertight. Next I welded tabs 161 -194 onto the side and front windscreen bows. These were then drilled with an 1/8" drill as was the centre windscreen bow. The windscreen was then positioned into the rear channel and starting from the back was match drilled onto the tabs with a cleco positioned into each hole as it was drilled. The drill used was a special version for drilling acrylic. This has a much steeper angle on the point and does not grab the plastic in the way a normally ground drill can. Finally, the windscreen was clecoed into position front to back. Next job is to trim the edges back to the windscreen bows but this will have to wait for a bit as I'm probably not going to get anything done over the next week or so but normal service should be resumed first week in November.

19th October 2008 - Left side window frame

I started today by jigging and tack welding into place strips of stainless steel behind the channel that supports the back of the windscreen. Then started final welding this into place when my Argon ran out when about a third of the way across so the rest will have to wait for another day. With no welding possible there was no option but to bend some aluminium so I started on the framing for the left side window. This sits on the outside of the fuselage butting against the window bows at the top and the stub longerons at the bottom. First job was to create a section of angle to support the bottom of the window from the inside. This will screw onto the tabs already in place to support the side of the combing. The outside of the window at the bottom will be supported by the aluminium skin that cover the first 18" of the fuselage. Next the two sections of angle that surround the top front door post were fabricated. the rear one is a U section that will screw to the outside of the window; the internal dimension of the U has to be equal to the diameter of the door post (3/4") plus the thickness of the window (2mm). The front one is a "step" shape that forms the support on the inside of the window; in this case the thickness of the step needs to be exactly 3/4". A 2mm spacer was sawn out of wood to mimic the thickness of the windscreen and can be seen clecoed between the two sections. It took two goes to bend the rear section to exactly the correct width but the front one worked first time. The front/back dimension of the box created around the door frame by the two sections is about 1-1/8" to allow room to duct the cables and pitot tube up to the wing root from behind the panel.

18th October 2008 - Windscreen

I started work today by installing the piece of stainless steel channel that forms the top of the fuselage over the rear spar carry through. This has the front edge of the top fabric wrapped round it and a section of spruce inserted into the bottom to anchor the fabric. Then a section of aluminium sheet screws through the section and into the spruce to close the gap to the back of the windscreen. This sheet will also provide a suitable mounting for the GPS aerial. Next the windscreen itself was clamped into position using a piece of wood to keep the rear edge flat. The windscreen is a sheet of 4mm acrylic (perspex). The centre windscreen bow was then shaped to fit against the natural curve of the windscreen. This took quite a few iterations but eventually there was a good fit from front to back. The windscreen was then removed and a suitably sized stand-off fabricated for where the centre bow passes over the front spar carry through. Then the centre bow was welded into place; front, back and to the stand-off. I was unconvi9nced that the aluminium sheet would provide a neat rear edge to the windscreen which wants to bow and the sheet would probably not be strong enough to fully prevent this so I welded a second piece of stainless steel channel on edge to capture the rear of the windscreen, keep it in a straight line and anchor it against the three windscreen bows. This works very well as can be seen in the picture. Next I need to weld 30 or so tabs to the outside windscreen bows and across the top of the firewall. The windscreen will be match drilled to these and then cut to final shape. I've have made work for myself by using the channel at the back of the windscreen as to create a seal to the aluminium top panel I will need to weld a ledge to the back of it across the entire width to create a weather seal rather than just using tabs.

17th October 2008 - Left windscreen bow and wing attach brackets

My TIG welding machine will only do DC welding whereas you need AC for aluminium so yesterday I took the completed fuel tank to the local aluminium welding guru to be finished. Today was another beautiful autumn day so Paul and I took the Vans from Andrewsfield (pictured) to Old Buckenham for lunch. We flew along the east coast before cutting inland and the third picture is of Southwold, one of the most picturesque Suffolk villages. I did get a bit of work done later in the day and welded the left front spar attach bracket and left windscreen bow to the fuselage.

14th October 2008 - Rear spar carry through tie rods, left wing attach brackets

Now that the position of the rear spar carry through has been established fairly accurately the last couple of tubes that form the main fuselage structure could be added. The right one welds between the rear spar carry through and the upper fuselage diagonal just in front of station 78. The left welds back to the top fuselage cross member at the station. Later plates that form the upper seat belt mounts will be welded between the rear of these tubes and the longerons. Next the wing attach brackets for the left side of the fuselage were fabricated. Again it took much longer to make these than seems reasonable but it is critical to get the dimensions exact to fit inside the spar attach brackets.

13th October 2008 - Right side door

As previously noted the left side door had been made too tall and would not have opened under the wing. To get this correct for the right door I made a template of the bottom half of the main wing rib. This was attached to the root rib template referenced via the cord line. A straight edged piece of scrap timber was then clamped to the fuelage stretching horizontally across the door opening to define the position of the top of the door opening. This was set 3/8" lower than the bottom of the main rib template to allow for the door panel to overlap and create a good seal. Then the right door was fabricated in the same way as the left. See http://tailwindbuild.blogspot.com/2008/08/14th-august-2008-left-door.html , http://tailwindbuild.blogspot.com/2008/08/17th-august-2008-seat-bottoms.html , and http://tailwindbuild.blogspot.com/2008/08/18th-august-2008-left-door-latch.html for details. Finally the left hand door was shortened to the same dimensions as the right so it should now open!