30th May 2009 - Fuselage and empennage signed off

Had a good day today with my inspector signing off the fuselage and empennage of my W10. In the UK we build under the control of the Light Aircraft Association (LAA was PFA) and a qualified inspector has to inspect the work at pre-specified stages through the build. Today I got two of the major stages signed off.

Complete empennage structure for alignment, dimensions, welding and quality
Fuselage structure for alignment, dimensions, welding and quality. Fittings attached.

Basically, I'm now ready to paint and cover the fuselage and empennage, but I'm going to wait until I've test hung the engine and sorted out all the firewall locations so I can weld any brackets I need to support things like the battery before I paint. Still it feels good to have the framework together and looking like a Tailwind - pity it all has to come apart again.
I'm sorry there has been no entries over the last week but I've been working flat out to get the aircraft ready for the inspection today. Basically, this has been an iterative process of test fitting items, making adjustments, refitting, etc. It's extraordinary how much time this takes to get things exactly right. Holding things together with clecos can mask a number of problems. For example, one of the nuts needed to secure the autopilot servo to it's rails couldn't be installed as it was too close to the tab holding the rail itself - no problem with a cleco through. I've also had to add nutplates in various places where it was not possible to get a conventional nut into place as other components are added. For example, the centre support for the rudder torque tube bolts through the inner floor panel into a plate welded to the fuselage structure. The outer floor panel has to be installed before the inner and the plate is between the two - not possible to get at so rivet on a nut plate. Likewise the side cheeks have screws along the top edge which screw through the side windows and into tabs on the upper stub longeron but you can't get at these with the tank in place and the tank has to be in place before the side cheeks to get all the cabling into place - more nut plates. All this has taken time repeatedly installing and removing panels.

The only disaster during the week was with the main windscreen. The holes in the plexiglass windscreen were drilled to final size and countersunk. The windscreen was then screwed into place first down the centre and then down the left side - all OK. Next as I was screwing down the right side there was a loud noise and I looked up to find that the windscreen had cracked all the way from the left edge just behind the front spar carry-through to the centre. The screen was duly removed and the crack appeared to have started on the edge of one of the supporting tabs on the left windscreen bow. I assume that in tightening the windscreen down it had bent too sharply across the edge and caused the crack. So the edges of the tabs were all bevelled to reduce the possible stress and a replacement piece of windscreen procurred - polycarbonate this time. This material is much stonger than plexiglass and also more flexible (and more expensive) but this time it was cut out and drilled without a problem and fits nicely.

I also spent a long time getting the fit of the doors exactly right. The right hand door was hung slightly too far in at the top and was rubbing on the edge of the combing. To solve this the top hinge bracket was cut off the door post and a new one fabricated, welded into place and re-drilled with more clearance.

Installing the seat belts was more work, the seat side panels and flap lever cover had to be cut out to allow the belts to pass through and a supporting strip fabricated at the back of the baggage compartment to support the cables for the shoulder straps.

Anyway, it all came together in the end and passed the inspection with flying colours.

I'm now going to take a break from building until mid July. Hopefully by then the engine should be back from the shop and I can get it mounted and finish off the firewall. Next post is scheduled for Friday 10th July

22nd May 2009 - Changing the workshop layout

I'm building in a single garage attached to the house measuring 8ft by 19ft so I'm pretty tight for space. As much of the work as possible has been done on the drive outside weather permitting. Up until now I've had a full length workbench along the left side of the workshop which I've used for jigging the fuselage sides and supporting the structure as it has been constructed. This has mean't repeatedly installing and removing the gear/engine mount and gear legs to get the fuselage into and out of the garage. Next major jobs are the installation firewall forward and the construction of the wings so I've reduced the workbench to a 8ft * 4ft area which should be just about OK to build each wing panel and this lets me keep the fuselage on it's gear which makes it much easier to get in and out. It's a snug fit but just about workable. Once I've done the basic firewall forward install and located the various items that mount to the firewall I'll strip the fuselage for painting and then it can be stored offsite until the wings are finished but I don't want to do this until all the welding is completed and that can't happen until I have put in supporting structure for items such as the battery which will mount on the firewall - too many dependencies! Anyway today was cleaning tidying and reworking the space so no progress on the build.

21st May 2009 - Baggage compartment nut plates

Hopefully, that's the end of the nut plates for the moment. First job today was to final fit the right inner overdoor panel which screws onto the "U" in the bottom of the outer panel using 5 spire clips. Then the angles which will support the baggage compartment walls, floor and the rear bulkhead panel were drilled to final size and 10 off #8 miniature nut plates riveted to the various tabs to support them. The tabs were countersunk and the angles dimpled to allow the screws to lie flush with the angles. Once everything was drilled and dimpled the angles were then deburred where they had been rough cut with the angle grinder.
I'm intending to use Correx (polyboard as used for estate agents signs - realtors signs for US readers) for the walls and rear bulkhead. I haven't decided about the floor yet, wood aluminium or a double thickness of Correx are all possibilities. I will need to add an additional cross member two thirds of the way up the rear wall to the baggage compartment to put a joint between two sections of the wall to allow the seat belt cables to enter from their attach points at station 111. This is the approach Vans uses in the RV series aircraft.

20th May 2009 - More platenuts

It was too boring for pictures again but got a lot done today.

1. 1 tab and 4 off #6 miniature platenuts installed to mount the right rear window
2. 10 clinch nuts installed to mount the baggage compartment roof bars
3. 9 clinch nuts installed to mount the rear spar carry through cover
4. 6 clinch nuts installed to mount the two inner above door fill panels
5. 5 spire clips installed to mount the left inner above door fill panel
6. 10 holes tapped for # 8 screws and 12 spire clips installed to mount the external antenna panel above the rear spar carry through
7. 24 plate nuts installed to secure the right side and centre of the main windscreen

Tomorrow the main job is to install the platenuts to mount the baggage compartment rails.

19th May 2009 - Platenuts

No pictures today - just lots of plate nuts installed:
4 off #10 to mount the tank side support brackets
8 off #8 on the tabs that will secure the front of the main screen
12 off #8 on the tabs that secure the left side of the main screen
2 off #8 countersunk in the top of the seat side fill panels
12 off #6 in the left and right rear windowsills
4 off miniature #6 in the left rear side window frame
1 additional tab welded into place to secure the far rear of the left rear screen surround

In addition the lower cross member at station 18 was tapped to take #6 screws to secure the rear edge of the front underfloor panel. I had intended to use self tapping screws for this but the 0.028" thick stainless channel that forms the cross member was too hard for the screws with it removing the thread from the screws rather than them cutting a thread in it!

Predictably all of the panels installed yesterday other than the firewall had to be removed today to install the various platenuts - duh...

18th May - Build Order (work in progress)

1. Install firewall
2. Install engine mount and main gear
3. Install tailwheel
4. Install all cable bushings
5. Temporarily install panel and fuel tank
6. Install strobe pack
7. Install cabling to tail-light/strobe
8. Install static port tubing
9. Install pitot tube to junction in rear spar cover box
10. Install VOR antenna cable to junction in rear spar cover box
11. Install GPS, and Comm antenna cables
12. Install wing nav light and strobe light cables to junctions in rear spar cover box
13. Remove panel and fuel tank
14. Install combing and front, left and right side combing trim panels
15. Install fuel tank
16. Install flap torque tube
17. Install flap lever to torque tube pushrod
18. Install rear floor panel (rudder cables pass through this)
19. Install rudder cables, temporarily install rudder, make off rear ends of cables to length, remove rudder
20. Install seat belt shoulder straps
21. Install seat bottom centre panel
22. Install left and right seat bottoms
23. Install outer seat belt lap straps
24. Install elevator pushrod
25. Install baggage compartment angles
26. Install seat side fill panels do not screw into place
27. Install rear window sills, do not screw into place
28. Install rear window diagonal covers
29. Install rear window surrounds, do not screw window surrounds to rear window sills until after fuselage sides are covered
30. Install all stringers
31. Cover fuselage sides
32. Install static ports and connect to static tubing
33. Install rear windows
34. Complete fuselage covering
35. Install brake pipe flexible terminations
36. Install brake master cylinders
37. Install lower fuselage forward skin
38. Install transponder antenna
39. Install fuel tank breather outlet and tubing
40. Install forward floor panel
41. Install rudder pedals
42. Connect flexible brake pipes

18th May 2009 - Start of fuselage test build

The fuselage is basically complete ready for painting and covering, but I've never had all the components installed at the same time and I need to ensure that all the mountings are drilled to final size and that where necessary nutplates or clinch nuts are installed. There is also a logical order of build that I need to understand such that the various components can be installed without having to remove others. I'll develop this on a separate page on the blog. For the test build, I'm going to put the aircraft together starting with the firewall and working rearwards so today I started by deburring the firewall, dimpling the holes where it screws to the fuselage and the holes round the edges and bottom where it will rivet to the side cheeks and underfloor panel. The holes in the mount tabs on the fuselage were drilled to final size and countersunk for #6 stainless steel screws and the firewall screwed into position. Next the underfloor panel was dimpled where it rivets to the firewall and where it screws to the fuselage. Cut outs were made to clear the stub struts which were not there when the panel was originally made. It was then mounted in position. Holes were drilled in the panel for the brake pipe connections. Next, two supports were fabricated out of 0.063" thick 4130 steel plate and drilled to take the fuel tank breather outlet and the transponder antenna These were welded onto the lower cross member at station 18 with their bottoms lying flush against the underfloor panel. Matching holes were then drilled in the underfloor panel. Last job today was to install the left cheek panel which also needed cutting out round the stub strut. Tomorrow, after the right cheek, it's installation of nutplates to mount the main windscreen. I think it's probably going to take 10 or so days to get the fuselage fully built but at that point it should be ready for painting (after it's all been taken apart again!).

17th May 2009 - Cable Runs

I made big progress today installing the mounts for all the cabling as well as the pitot and static systems. First I made a simple jig on the drill press to cut out evenly spaced 5/8" holes in some strips of 0.063" steel. These holes will be lined with SB625-7 plastic bushings to protect the cables. The plates were made with varying numbers of holes from 1 to 5 depending on the cabling density in various parts of the fuselage - there are probably more routes than needed but the experience with the RV9A of trying to get additional cables through a limited number of routes persuaded me to be more generous this time. Also, the wiring scheme keeps sensitive antenna cabling separate from power cabling The basic routing is from the panel, over the fuel tank and down between it and the firewall, then under the floor through to the baggage compartment. Once clear of the elevator pushrod the cabling will then sit on the inside of the fuselage through to the tail and then up the front of the horizontal stabiliser spar to the rear light/strobe. Behind the baggage compartment the route also branches up to the top of the fuselage and then forward into the rear spar cover where the pitot tube and wing cables will enter the wings and where the GPS and Comm antenna are mounted. Five smaller plates to take SB375-4 bushes were also welded round the fuselage uprights and top cross member at station 111 to take the static tubing from the left to the right side of the fuselage (picture 4).
In detail the routes are as follows:
Route 1: Panel to strobe pack power behind station 78, panel to tail nav light, panel to wing nav lights, strobe pack to tail strobe, strobe pack to wing strobes
Route 2: Panel to wing mounted pitot tube, panel to comm antenna behind rear spar carry through, panel to static ports at station 111
Route 3: Panel to GPS antenna behind rear spar carry through, panel to wing mounted VOR antenna
Route 4: Panel to autopilot servo behind station 48
Route 5: Panel to transponder antenna situated on the left side of the floor between station 0 and 18, fuel tank to breather port situated on the right side of the floor between station 0 and 18

16th May 2009 - Brake flexible hose terminations

I've spent the last couple of days planning out the routing of all the bits and pieces needed to make the various aircraft systems work: pitot, static, fuel, cabin heat, cabin air, engine controls, wiring, tank venting and brakes as I want to get all the appropriate mounting plates welded to the fuselage structure ready for painting. I think I've got it all sorted back from the firewall, but I'm going to need to temporarily hang the engine to finalise the various firewall mounted items that will need supporting brackets (e.g. the battery). Today I welded into place a couple of plates that will mount the AN fittings that connect the flexible brake pipes coming from the master cylinders to the aluminium tubing that will run down the back of the main gear legs to the brakes. The tubes will eventually be covered by the gear leg fairings and the fuselage intersection fairings. I also reworked the straps across the top of the fuel tank as these were too loose. I'm still maintaining my "to-do" list http://tailwindbuild.blogspot.com/2009/03/25th-march-2009-list.html of jobs needed to get the fuselage ready for priming/painting and it's slowly getting shorter. Trouble is I'm also building up a list of "to-dos" ready for when it is painted!

14th May 2009 - Installing the Stub Struts

The stub struts mount to the lower longeron at station 18 and are angled up 35 degrees from the horizontal. So the first job was to make a jig to support the stub strut in position for tack welding. Once this was positioned the end of the stub strut was through progressive iterations shaped to fit round the various tubes meeting at the station 18 cluster - much easier to say than do! The stub strut was then clamped into position on the jig and tack welded. The jig was then removed and the stub strut final welded into position all the way round. Next a reinforcing plate made of 0.049" thick 4130 steel was shaped to fit onto the bottom of the stub strut and round the lower longeron. This was welded into place progressively, clamping each section tight to the underlying structure, starting at the outboard edge and welding that section before moving the clamps inboard. The inner end of the plate was cut so that the outer sections could be curved round the longeron and the central section welded to the cross member. Then as always the process was repeated for the other side. The last picture shows the struts in place in the stubs. The struts join to the wing 48" out from the fuselage and within the margins of measurement error appear to be correctly positioned. Next job is to re-install the fuel tank and work out a cable rounting from behind the panel to under the baggage compartment. If I can find a way to do this tidily it should be possible to keep all the cabling and pitot/static tubing neatly hidden.

13th May 2009 - Stub struts and strut forks

Serious structural work today. The struts hold the wings in position so it's important to get this bit correct. Although the plans are fairly clear I wasn't sure exactly how to go about making the ends on the strut and stub strut but thanks to Jim Stanton and his article in a back issue of the Tailwind times (TT10) the approach became clear. The struts are made from streamline 4130 steel tubing 2.5" wide, 1.0" deep and with a wall thickness of 0.049". The cross section of the tube is like an elongated egg shape to minimise drag.
An 11' length of tubing is sufficient to make the two struts and two stub struts (these are welded to the fuselage). The 11' length was cut in half and then the first job was to flatten the end of the tubing that will be used for the stub strut. The line on the tubing marks the start of the taper down to the end. Once the end was down to rough size (0.095" gap), the sides of the tube were cut off to make a wedge shape. Next job was to cut a piece of 0.095" thick steel plate 1-1/4" long and matching the wedge shape to fit into the end of the tubing. With the end clamped in the vice this was then welded into position as in the second picture. Next, strengthening plates made from 0.065" thick plate were cut out and clamped to the sides of the joint (3rd picture). These were then welded into position. This creates a flat area roughly 1-1/4" square with an even thickness of about 0.325"and a 3/8" hole was then drilled centrally in this flat to take the mounting bolt. A second end was made in the same way on the other length of tubing. The two stub struts were then cut from the lengths of streamline tubing ready for welding to the fuselage.
The lower end of the first strut was then prepared. First, a piece of 0.065" thick steel sheet was folded into a "U" shape to fit over the end of the stub strut. The end of the sreamline tubing was flattened to create a rectangular end the same size as the outside dimension of the "U" which was welded into place as shown in the 5th picture. Finally strengthening plates were welded to the outside of the tubing and the fork drilled to take a 3/8" diameter bolt. As before, the process was then repeated for the second strut. Next job is to weld the stub struts to the fuselage.

12th May 2009 - Right hand door panelling and window

I started today by laying out the right door window and given that I had enough lexan left over I remade the left front side window which had been double drilled to fit the left door http://tailwindbuild.blogspot.com/2009/04/13th-april-2009-left-door-skin.html . The rest of the day was spent making the right door skin and fitting it and the window as per the left door. I got a good fit this time so a thin neoprene strip on the front door post should make it draft proof. I've got one minor bit of rework to do on both doors. Now the skins are on the door latches fit too tightly behind the rear door posts so I need to space them off the door frame by about 1/8" each otherwise when the fuselage is covered they won't close at all.

11th May 2009 - Right side panelling

It's always seems harder to motivate myself to do the components for the second side of the aircraft. The first side has all the intellectual challenge of solving how to do something, whereas the second side is just repetition. However today I got stuck in and fabricated and installed the filler panel between the right seat and the door frame, the right rear window sill and the cover for the frame diagonal and the right internal over-door filler panel. The last picture shows the way in which the rear edge of the seat filler panel, the edge of the window sill, the edge of the diagonal cover, the forward edge of the rear baggage compartment upright and the upper edge of the right side baggage floor support create the framework that will take the baggage compartment wall panel.

10th May 2009 - Baggage compartment angles and tabs

I started today by positioning and installing another 28 tabs: 3 to secure the right interior over door panel, 7 to fix the rear spar carry through cover, 8 to fix the left and right baggage compartment roof lining side supports, 1 to fasten the right seat filler panel, 7 to mount the rear bulkhead angles and 2 to fix the front of the baggage floor side angles. That makes a total of 315 so far but hopefully that's pretty much it. Next job was to bend strips of 0.050" aluminium to make the baggage compartment floor support angles and the baggage compartment rear bulkhead support angles. These were cut to length and match drilled to the tabs to create the basic baggage compartment framework. The rear spar carry through cover was then match drilled to it's tabs. The rear of this acts as the front edge for the baggage compartment roof lining. Next a piece of 0.025" aluminium sheet was folded to provide a cover for the left fuselage side diagonal behind the rear side window. This was drilled to the rear window sill and creates an upper edge for the baggage compartment side wall. Finally, two lengths of 0.025" aluminium sheet were folded to create the roof lining side supports and these were match drilled to their tabs. The roof lining does not extend all the way to the side of the fuselage as a space is required for the aileron and flap pushrods to connect to the levers on the torque tubes. The last picture is looking up in the fuselage with the front to the top of the picture and shows the gap between the upper longeron and the edge of the right hand roof lining support

7th May 2009 - Left interior above door fill panel, rear spar cover

I spent much of last week diagnosing and fixing a blocked sewer. The problem eventually turned out to be a complete fracture of a pipe caused, presumably, by the ground drying and settling. Of course the section in concrete didn't move whereas the section in the soil did by about 5" downwards. This snapped the 4" pipe completely which blocked everything. Given that all this happened a 30"underground it resulted in some back-breaking digging to get at it and graft in a new section of pipe. Anyway all is now "flowing" so it's back to building. Today I fabricated the left interior above door filler panel and welded into place 3 tabs to secure it. This followed the usual process of making a cardboard template and then cutting the aluminium to match. I also fabricated a panel to cover the rear spar carry through. This was bent to fit into the channel that carries the back edge of the window and its rear edge will form the support for the roof lining for the baggage compartment. Two tabs secure the panel at the front. There are still another five to add to the rear spar carry through at the rear. The combination of the roof lining , the rear spar cover and the interior above door panels will allow me to run the cables and pitot tubing to the wings invisibly and keep things neat and tidy.