28th April 2009 - left seat fill panel and left rear window sill

I've been puzzling over how to create a neat join between the seat edge and the door frame and how to link this in with the panelling that will cover the fuselage sides inside the baggage compartment. Today I finally made some progress on this. First a piece of 0.050" thick aluminium sheet was cut out and riveted to the left seat panel in a similar way to the rudder cable cover - http://tailwindbuild.blogspot.com/2008/09/18th-september-2008-left-rudder-cable.html except in this case it was aligned to rest at the top against the fuselage cross member at the bottom-rear-corner of the door opening and angled to fit against the back of the lower section of the seat. An equivalent piece was also riveted into place on the right side. Next a piece of 0.025" aluminium was folded into a "U" shape to fit the gap from the fuselage cross member up to the level of the bottom of the rear window. This is a wedge shape as the fuselage is wider at the top than the bottom but the seats are upright and requires various cut-outs to clear the fuselage tubing. The top front and edges were folded over and riveted to make box structure and the inside edge of the piece was left long enough to protrude behind the seat back and will form the front edge of the mount for the baggage compartment left wall. The bottom edge of the piece is secured behind the filler panel riveted to the floor panel. The top was screwed to a tab welded to the door post. Next another piece of 0.025" aluminium sheet was folded to form the rear window sill and the top mount for the baggage compartment side wall. This will screw to the inside of the window and side panel along it's outer edge and the top box of the previously made section. This will eventually require cut-outs to allow the aileron and flap push-rods to pass through to their respective control horns but by spacing the baggage side wall away from the fuselage covering will protect the controls from the baggage.

24th April 2009 - Seat Belt Brackets

Another few items off the list today - I fabricated and installed the brackets for the seat belts. First templates were cut out from card to fit the various locations then these were copied onto 0.090" thick 4130 steel plate and cut out on the band saw. 1/4" holes were drilled to take the seat belt mount bolts. The brackets were then welded into the fuselage. The brackets for the shoulder straps were positioned at station 111 and welded to the longeron, the cross member and into the cluster (picture 2). The plans actually show them at station 78 but this positions them to the outside of the seat whereas at station 111 they get a straight run to the centre of the seats. This mimics the approach Vans Aircraft use in the RV series. A cable will be used to connect the seat belt shoulder straps to the bracket. The outer brackets for the lap belts were welded into the angles formed between the rear door post and the bottom longeron. The centre bracket is welded between the flap lever support tube and the centre upright. In all cases I'm confident that the bracket fixings are stronger than the seat belt hardware.

23rd April 2009 - Engine mount complete

Spent the morning welding the engine mount. No real issues and the cluster joints were easier than those in the fuselage because it was possible to move the mount round easily to get the torch to the joints. As much of the welding as possible was done with the mount bolted to the jig to ensure that it stayed accurate. The final result is good with the mount holes exactly on the 11.5" * 9.5" grid needed and the mount plates parallel to the firewall within 0.1 degrees ( despite what it looks like in the first picture). This is the last of the big welding jobs in the build. The engine is away at the engine specialists doing the shock load inspection so when it comes back I can test fit it to make sure everything fits and then get the mount powder coated.

Remember you can click on the pictures to get a larger image.

22nd April 2009 - Engine mount

The tubing arrived so I made a start on the engine mount. First job was the cut four short lengths of 3/4" * 0.120 tubing and weld them to 3/32" thick washers. These take the bolts which pass through the rubber bushes that mount the engine and are shown in the first picture on a piece of scrap board. The undercarriage mount was then bolted through the jig frame (http://tailwindbuild.blogspot.com/2008/05/4th-may-2008-engine-mountings.html) to the work bench. The piece of scrap board was drilled with four holes to the exact pattern required for the mount bolts (11.5" * 9.5") and the holes duplicated in the building board symmetrically about the centre line of the undercarriage mount and 10" up from the bottom of the fuselage as called for in the plans. Next came the magic courtesy of Earl Luce and the EAA web site http://www.eaa.org/video/homebuilders.html?videoId=16346696001 . Four lengths of 1/2" threaded rod were fastened to the holes in the building board with a pair of nuts and washers each. Then an additional nut was positioned on each rod and the engine mounts placed on top. Finally the scrap board was positioned over the rods and washers and nuts added. The board was then leveled exactly 10-3/8" above the workbench (9-3/16" + thickness of the frame) by adjusting the nuts. The top nuts were then tightened to clamp everything in place. Next it was a case of cutting and tacking the various lengths of 1/2" * 0.058" tubing into place (the fourth picture shows the first pair of tubes in position) until finally all the tubing was installed. Tomorrow, it all gets final welded.

21st April 2009 - Right rear window

Just like http://tailwindbuild.blogspot.com/2009/04/17th-april-2009-left-rear-window.html only on the right side. Just the right door to do and that's the glazing finally finished. Total tabs installed now 282.

20th April 2008 - Undercarriage rework

The tubing for the engine mount arrives soon so I wanted to get the undercarriage mount exactly correct first. As originally built, with the wheels level, the fuselage was about 0.9 degrees low to the left. Although this doesn't sound very much it represents about 0.6" over the width of the fuselage. I decided to correct this and get it as accurate as possible. Part of the difference was removed by re-drilling the undercarriage socket mount holes but this only yielded an improvement of about 0.3 degrees so the tie rod between the top of the two undercarriage leg sockets was cut at the weld with the left socket allowing the left leg to pivot down slightly. A piece of 1/4" plate was then cut into a disc and tack welded between the socket and the cross tube to fill the slight gap created. This corrected the remaining error so the undercarriage mount was then removed and the joint final welded. The extra mount holes were also filled with weld metal. The mount was then replaced and everything re-measured. As always with welding there was some slight movement and an error of between 0.1 and 0.2 degrees had returned but that will have to be near enough. The toe-in was re-measured at exactly 1.5 degrees for both wheels. The line of the extended axle between the wheels is exactly parallel to the firewall, and the sideways displacement of each wheel from the fuselage is the same within the limits of measurement accuracy so I assume the aircraft will track straight which is pretty important for a tail dragger.

18th April 2009 - Static port support plates

Just a few minutes to work on the aircraft today, so I completed one of the small outstanding jobs by fabricating and welding into place small plates of 0.032" steel which will be used to mount the static ports. These were bent into a shallow "L" section with the short edge edge of the L welded to the fuselage upright. These are positioned either side of the fuselage just in front of station 111 and jigged so that the long leg of the "L" lies flush with the stringers so that the fabric can be glued to the plates with no distrubance to the airflow. The two static ports will be joined by an inverted U tube to ensure that the static reading is not influenced by any sideways movement of the fuselage through the air (slipping).

17th April 2009 - Left rear window revisited

I hadn't been happy with the left rear window as previously built and after finishing it also realised that I hadn't really thought through fitting the fabric. Firstly, the window would have to be screwed in place after the fabric was fitted and my uneven screw positions would show, albeit under the paint. Secondly, with the positioning of the lower mount tabs the fabric would not be able to be folded round the window opening and stuck neatly to the inside of the window frame to make a smooth surface for the window to screw to. Finally, I didn't want to build the right side the same but did want them to match. Only one solution: re-do it. There were two possible options: completely reposition the upper stringer or move the lower mount tabs so that they wouldn't interfere with the window. The first solution will be how I do it next time I build a Tailwind, but more work than was reasonable this time. So, I cut off the lower mount tabs and re-welded new tabs to the bottom of the stub stringer. One extra tab was also welded into place to improve the support of the over-door panel (number 267!). Then a new window surround was made and match drilled to the mount tabs. Finally a new window was cut out and drilled to the surround with a neat even row of holes this time. As before the holes were deburred and dimpled in the frame and countersunk in the window to take #6 screws. I also decided to change the shape of the window this time and set the angle of the front edge to be a mirror image of the line of the back of the front side window. I think it looks better but design isn't my strong point.

16th April 2009 - Stripping the engine

For the last two days I've been working on the engine I bought to power the Tailwind. It needs an inspection to make sure any propellor strike has done no damage, This inspection requires splitting the crankcase and includes examining the crank for straightness and for any cracks, in addition all of the bottom end bearings are replaced together with the bolts holding the timing gears. To simplify the work for the engine shop the cylinders were removed together with all of the engine ancilliaries. The cylinders were cleaned, degreased and then treated with protective oil and then sealed in plastic and boxed up ready for refitting later. All looks in good shape with no corrosion evident and the crank turns very smoothly and evenly so hopefully there is no damage. The rear view of the engine shows the accessories housing where the magnetos, fuel pump, vacuum pump, oil filter and tacho drive fit.

14th April 2008 - Left side windows

I started today by cutting out a piece of 2mm acrylic sheet to make the left door window. I'd been puzzling how to mount this but eventually decided to use the simple approach of screwing it to the window surround. I've got a large stock of countersunk #6 Torx head stainless screws left over from the Vans so match drilled the window to the frame and then countersunk the acrylic and dimpled the surround to take the #6 screws. This has the advantage that the window is easily replaceable and is very secure. Next I fabricated the aluminium panel used to mount the rear window. This was match drilled to the tabs installed previously - http://tailwindbuild.blogspot.com/2009/03/26th-march-2009-left-rear-window-mount.html . The rear edge and the bottom edge were folded inwards 90 degrees to stiffen the panel and the top edge and front edge bent in slightly using an edge roller to fit tightly against the door frame and top longeron. At this point a problem became apparent: I wanted to have the bottom of the rear window in line with the bottom of the door window and bottom of the front window. However, the line of the stub stringer that forms lower mount for the rear window frame starts at the door post exactly level with the bottom of the window in the door and then slopes downwards as the fuselage narrows towards the rear. In order to keep the window bottom in-line it was necessary to start the opening 4 inches behind the door post, shorten two of the mount tabs and use an uneven placement of the lower window mounting screws. The rearwards start does have the advantage that it will hide the aileron and flap linkages and the screws will be hidden by the fabric which will cover the rear window frame. I don't think the fact that there is an angle between the bottom of the window and the stringer will look odd once the covering is in place. I'm continuing to keep my to-do list up-to-date http://tailwindbuild.blogspot.com/2009/03/25th-march-2009-list.html and was able to completely remove one item today. I'd been assuming that I would mount a VOR antenna on the horizontal stabiliser. However, I emailed the guru of antenna for homebuilt aircraft - Bob Archer and he very kindly sent me a design for a dipole antenna and matching balun that can be built inside the wooden wing. Not only will this be much neater but the cost will be much less than a commercial VOR antenna.

13th April 2009 - Left Door Skin

A couple of days ago I ordered the tubing to make the engine mount. The tubing kit I had ordered from ACS had included a length of 1/2" * 0.049 which would have been OK for an O-200 mount but the plans call for 1/2" * 0.058" for an O-235. Today I fabricated the skin for the left hand door. First a sheet of 0.025" 6160-T6 aluminium sheet was cut to approximate size to cover the complete door frame. Then this was slotted to fit over the two hinges. Next, the outline of all of the tubing was drawn onto the sheet. The sheet was then removed and holes laid out for the #4 screws that secure the skin to the door frame. The skin was then replaced on the frame and holes match drilled with a 2.3mm drill through the skin and the frame - a total of 37 in all. The 2.3mm holes in the frame were then tapped out to take #4 screws and the holes in the sheet opened up to allow the screws to pass through. I've found some really neat 1/4" long pan head #4 screws that take a 1/16" allen key to tighten them. The front edges of the door skin were then folded at right angles to butt against the forward door post and the remaining edges trimmed to give about 1/2" overlap at the rear and bottom and 1/4" at the top where the door has to open under the wing. The door skin was then temporarily screwed into place on the door frame and the door hung on the fuselage. The gap along the front of the door from the bottom up to the the window was just right to allow a strip of door seal rubber to completely close it. The gap above the bottom of the window started OK but then widened unacceptably towards the top. This was corrected by notching the front bottom edge of the above door panel by about 3/16" and then pivoting the top of the side window angles rearward from their bottom fastening and re-drilling through the side window - this closed the gap perfectly but will mean I need to replace the left side window as it now has slotted and/or duplicated holes in the rear edge. The final job today was to cut out for the window. The line of the bottom of the front side window was carried across to the door and a couple of holes drilled to locate its position on the inside. The opening was drawn by using the spacing from these holes to the door frame cross member all the way round the frame. 1/4" holes were drilled at the four corners and a 1mm thick stainless steel cutting blade in the angle grinder used to cut out round the hole. The angle grinder works superbly cutting aluminium sheet creating a straight clean edge that just needs a quick file to clean up.

3rd April 2009 - Forward fuselage complete

No post yesterday because I was half way through a whole set of tasks. But they all came together today with the completion of the structure of the forward fuselage and it's glazing. Jobs completed included: fabricating the right fuselage cheek panel and match drilling it to the support tabs and the firewall; fabricating the right windscreen support angles shown in the first picture, installing tabs 264 to 266 to support the two overdoor panels; fabricating the right overdoor panel and the right overdoor angle which closes the gap to the main screen; and trimming to final size the panel at the rear of the main screen. I won't be able to get into the workshop next week but it's always satisfying when you can look at a section that is not only complete but feels right.

1st April 2009 - Left over-door panel

First job today was to complete the fairing between the bottom of the windscreen and the firewall. The holes through the screen were drilled out for #8 screws, the fairing dimpled and the screen countersunk. Next the fairing was match drilled to the firewall using a #40 drill. This will rivet in place during final assembly together with the upper mount for the cowl. The main objective for the day was to close the gap between the top of the door and the windscreen on the left side of the aircraft. First the dummy root rib was positioned to identify where joints in the panelling could be positioned to be hidden. Note the way that the top of the screen follows as much of the line of the top of the root rib as possible. This was done deliberately http://tailwindbuild.blogspot.com/2008/10/10th-october-2008-windscreen-support.html to make the intersection between the fuselage and wing as clean as possible. Next a piece of 0.025" thick 6160-T6 aluminium was cut out to fit over the spar attach brackets. The top was trimmed flush with the top of the windscreen. The bottom was folded into a "U" section to stiffen the edge where the door will seal. The "U" will also provide a support for the wing strobe and nav light cables and the pitot tube. An internal trim panel will then be screwed to the inside leg of the "U" and tabs on the top longeron to tidy up the interior. Next a piece of the 0.025" sheet was cut out and folded into a right angle section to form the joint between the top of the above door panel and the screen. This was then shaped using the shrinker to conform to the shape of the top of the screen. It was then match drilled to the windscreen support tabs and the holes dimpled/countersunk as before. That completes the above left above door panel with the exception of welding in place attach tabs for it and the internal trim panel.