Elevation

Saturday 29th March 2008 (5hr 5min)

Riveted VS skin to forward spar and mid-span rib. Riveted in VS-706 tip rib VS-704 root rib and VS-705 nose rib. Replaced bad rivets in rear spar assembly and riveted it in place. Levelled table, drilled out and replaced bad rivets on left elevator top and bottom skin stiffners. Riveted top skin to the spar. Weighted left elevator and pop-riveted main spar to bottom skin. Riveted E-905 root rib and E-907 trim spar to bottom skin. Replaced faulty rivets in right elevator stiffners.

Dorothy and I continued our riveting partnership by completing the internal skin to spar and mid span rib rivets. I then inserted the two root ribs and completed the riveting of these plus the rear spar and the tip rib after fixing some bad rivets in the rear spar assembly that had been identified in the inspection. Being mostly around the edge of the skin, these rivets were easy. Only the three rivets through the two root rib flanges and the forward spar were a little tricky but the air squeezer easily got these done as the access is much easier that the similar joint at the root of each elevator.

Mick Bevin (my inspector) had suggested replacement of a number of rivets in the elevator stiffners. These had been put in before I realised the importance of adjusting pressure on the rivet gun and I had mashed some rivets by using too much pressure. Drilling out rivets is something you get a lot of practice at and I can generally get them out without touching the hole. Still, the process of setting the original rivet stretches the hole so you need a fatter replacement rivet. One way of making a fat rivet is to pre-squeeze a rivet of the next length up so that the shank expands and shortens. This will fill up the slightly enlarged hole. Doing this with an air squeezer is not easy but it is one way of developing a sensitive trigger finger.

I put on the elevator horn without any problem and then went on to rivet the elevator top skin to the spar. About 3-4 rivets either side of the hinge openings could be reached with the 4in thin-nose yoke.

Next, I weighted the elevator in the closed position with building sand divided among several of Dorothy's freezer food bags. Some people go to great lengths to get solid rivets through the bottom skin into the spar. I just went with the Vans suggestion and pop-riveted the join. Maybe I should have tried harder as the results were not wonderful, with a depression around each rivet. Good thing they are on the bottom. While the elevator was weighed down, I also riveted the root rib to the top and bottom skin and the trim spar to the bottom skin.

The trailing edges did not initially lie exactly on top of each other and had to be pulled into alignment and clamped using side-jaw clecos. This makes we worry about twist. Some builders have reported that they have perfectly straight trailing edges but with the two trailing edges aligned with each other only one elevator horn lines up with its elevator while the other one is well off. The solution seems to be to undo the end rib rivets and/or the trailing edge rivets, get everything into alignment while weighted down and re-rivet. I hope to avoid this by riveting both elevator trailing edges while mounted to the HS assembly and held 'in trail'.

On to the Vertical Stabiliser!

Friday 28th March 2008 (1hr 45min)

Prepared & primed R710 rudder brace. Assembled VS skeleton & skin in blocks.

I seem to be jumping around quite a lot from one assembly to another. A prime example was this evening when I worked on one rudder piece before going on to the vertical stabiliser.

I avoided the previous mistake (not leaving enough edge distance on the R-710) and cut strictly along the line from one guide hole to the next. For sure, there are no edge distance issues this time! After prepping the edges and cleaning/etching, I applied two coats of primer. It was not worthwhile getting out the spray booth for just one part so I used a paint pad to apply the primer. My pal Byran is applying all his primer in this way and is very satisfied with the results. I could see brush marks in the brace after it dried so I think I will stick with spraying. In any case, part of the point in spraying the primer was to acquire good spray painting skills by the time I come to put final coat paint on visible bits such as the cockpit interior.

In assembling the VS skeleton, I departed slightly from the Vans manual (temporarily ignoring the big lesson from last weekend) and followed George Orndorff's method instead. George feels that leaving off the root ribs (both the VS-704 main rib and the VS-705 nose rib) to improve access for rivetting the VS702 main spar and VS-707 mid-span rib to the skins. This could be further improved by also leaving off the VS-706 tip rib except that solid rivets are called for to attach this to the tip of the VS-702 main spar. However, I was determined to stick to somebody's method if not Van's so I riveted the tip rib on as per George's video.

Tool Trouble

Thurs 22nd Nov 3hr 50min

Prepared edges of R-901 skins, R-913 counterbalance skin and rudder ribs. Deburred and dimpled skins and ribs. Set countersink cage for #40 holes on R-916 trailing edge extrusion.

Dimpling the last 3-4 holes at the narrow end of the R-903 and R-904 rudder ribs is very tricky. Even the pop-rivet dimple dies are no use as there is not enough separation between the flanges to get the long nail that pulls the dies together into the holes. I looked on Doug Reeves Vansairforce forums and found various approaches. One is to drill and countersink a piece of mild steel and use it as the female die to make the dimple. Another builder had adapted his DRDT2 dimpler as pictured here.

While machine countersinking the hole in the steel with the bench drill and the #40 countersink cutter mounted in the hex adapter (that I usually use for my deburring bit), I managed to break the pilot off the countersink cutter. This was because the steel piece was not held securely and the pilot jammed in the hole when it came up off the table and the hole being countersunk moved out of the vertical plane. That will mean that I can't countersink the R-916 rudder trailing edge until I replace the countersink cutter (or borrow one temporarily from someone else).

I got down to the last two holes on each rib using the pop-rivet dimple dies and I tried using the mild steel die on the final holes with the normal male #40 dimple and a light hammer. However, I am not happy with the results. The test rivet did not sit properly into the hole. This is probably because the countersink cutter did not do its job properly before I thrashed it.

The final solution I came across was from Dan Checkoway, whose own website is legendary. He says simply bend the flanges out until you can get at them and then bend them back again. However, I wonder if the metal will be work-hardened by this process. In the end, I decided to partly follow Dan's advice. I gently parted the two flanges until I could just get the female pop-rivet die and nail into the last hole. The flange sprang partly back into position once the nail was in, leaving only a small 'permanent' deflection from its normal position. Once the dimple was made, I had to spring the flange slightly further out of position to get the nail head back out. However, after all the dimples were made, I was easily able to get the flanges back to square using the flanging tool. this picture shows a test rivet sitting in the last hole of the R-903.

Edge prep, Countersinking and Dimpling

Wed. 14th Nov 4hr 20min

Stripped vinyl from VS 901 skin. Deburred and #40 dimpled skin. Deburred, dimpled and edge preped spars. Prepped edges of skins and VS 808PP doubler. Countersunk fwd side of VS808. Dimpled #30 fwd side of Aft VS803 spar.

I had to go to Roscommon (West of Ireland) for a conference so I rearranged my schedule to work on the project during the afternoon and travel in the evening.

I dissassembled the VS and got down to preparing the edges of all the parts. I am particularly pleased with the technique for holding and supporting the edges of the large parts. Even the top and bottom edges of the VS skins proved to be very easy. Those engineering type vices that I got in Lidl and which attach to the edge of my bench were invaluable again. this time, I used some lengths of teak either side of (and between) the two skin edges. Wehn doing the top and bottom, which are a continuous V shape, I just used a shoter piece of timber in the middle..

You need to be careful about which holes to countersink on the VS808PP and dimple on the VS803 spar. It helps if you know how the finished unit will be fitted to the fuse. That makes it obvious that the lower end of the forward side of the VS803 needs to be flat so it can can be fitted tight against the bulkhead. That means it has to be dimpled in that area to take countersunk rivets and the doubler plate behind it needs to be countersunk to accept those dimples as it is too thick to be dimpled itself.

Angle of Attachment

Sun. 11th. 8hrs

Measured, cut and finished the HS908 attach angles. Match-drilled them to the forward spar.Started on the HS by assembling the skeleton and match-drilling the skin. Prepared the main nose and cap ribs

Friday was my son’s graduation ceremony (Mechanical Engineering – Trinity College Dublin) so no work on the plane. On Saturday, I just felt like a full day of goofing off and spent some time with my wife for a change. However, today I wanted to tackle this outstanding attach angle project. It went much better this time and I have two perfect attach angles to show for my efforts. I really need to get a finer Sharpie marker however. The so-called ‘fine’ tip is not really fine enough at all and the lines are not precise enough for my liking. It would be good to be able to use a metalwork scribe but that would be to invite stress fractures so its better not to have one in the shop.

That completed the work in the HS up to primer stage. While I have the primer in stock, I don’t yet have the other elements organised for the priming job.
So, being unable to move on to the assembly of the HS until priming is finished, I moved on to begin the preparation of parts for the next major structure; the Vertical Stabiliser. I believe I may prepare all the emp parts up to primer stage and do all the parts at the same time. This would mean setting up a spray booth just once.

The VS skeleton went together without problems. I thought about using the cradle blocks for the skin and then slipping the skeleton down inside. The manual is silent on how the skeleton should be wrapped. In the end, I just stood the skeleton on the bench and placed the skin over it and then just clecoed the skin on, beginning at the leading edge of the nose spars and working back. This seemed to work really well. It is in huge contrast to the complex assembly method that George Orndorff shows in his video. He was obviously dealing with an earlier kit in which the ribs were formed but not match-drilled. I would safely say that having the skin attachment holes on the rib flanges pre-punched saves at least two hours, if not four.

I see from his website that Smitty used some 4in foam blocks between the clecos on the underside of his VS to hold it off the table while he match-drilled the top. I decided that the number of clecos involved would distribute the weight well enough. Besides, the clecos are all attached into ribs and/or spars, where there is a lot of structural strength, rather than free-floating skin. Also, the pressure applied to the drill in match-drilling existing pre-punched holes is very small. I was glad that I saved myself the effort of locating suitable foam as the results were perfect.