37-06 -> 08: Riveting on the Roll Bar

The Roll Bar

The roll bar itself was riveted on in a fairly easy manner. I riveted it on with the forward bushing and the canopy lock pin in place, to make certain there was no misalignment of this pin which may have caused binding later. Since i painted the roll bar prior to installation, it means there are a few rivets which will not be painted - i think at this stage i will not worry about these. They acatually look pretty good in their natural state - but i can always touch the heads up with a brush later on if i choose. 

Van's really is clever - this flap of side skin was not riveted way back in Chapter 30 (aft fuse attach). This was becuase they knew i would need to pull the skin back here, in order to set the pull rivets. 

The locking pin bushing and the locking pin were in place when riveting on the roll bars, to make sure everything stayed in alignment and there would be no binding of the pins later.

The finished roll bars. I think the un-finished rivets look ok. Both pins are very free and ride in the bushings easily.

Roll Bar Brace

The roll bar brace was clecod in place, then i used the rotisserie to rotate the whole fuselage onto its side. This gave excellent access. The forwrad most rivets were easy - all pull rivets, inclusing some cherry rivets. 

You can see how the locking ring is in place in each rivet, locking the steel mandrel in position.

Below is a video of the cherry rivet setting process - as the rivet is set, the stem is pulled into the rivet head, deforming it into a bulb. When it is fully set, the shear ring on the stem breaks (the first click). Further pulling then drives the locking ring down into the rivet, and locks the stem into position. The stem them breaks off flush with the top of the locking ring (the second click). The anvel ring and the stem them shoot across the shop trying to get into your eyeball, but ending up in the toolbox. 

The rear end of the roll bar brace was a little more challenging - the rivets between the skin and the brace side brackets were fine, and i used a squeezer for these. The rivets between the roll bar brace / brackets and the aft bulkhead were some of the most challenging of the project so far. My very long straight cupped set was invaluable here. These would have been almost impossible without the rotisserie.

My long straight set was the only one which i could get to fit here.

The rivets between the roll bar brace side brackets and the skin were done with the squeezer.

Skin Stiffners / Skin

The final step was to rivet the side skins onto the fuselage longerons, and attach a skin stiffner to the skin. I used the squeezer for the stiffner, and the gun and bar or set the skin to longeron rivets. 

That's the roll bar Chapter 37 complete - next up is to work on the forward skins, and the canopy frame.

Final Painting Chapter 35 & 37

I left off Chapter 35 - Upper Forward Fuselage at the point where the parts needed to be painted in the final cockpit colour, before being riveted in. Similarly, i left Chapter 37 - Roll Over Structure at the same point. 

The problem was that it has been winter here in Australia, and i have been unable to break out the Stewart Systems EkoCrylic, as it needs to be shot above 15c. I shelved a bunch of components from the above chapters and moved onto the parts preparation of the canopy. 

Spring is now here, and we have had a couple of days in a row above 20c, so i decided to get stuck in and paint all the remaining parts in one go. Each of the parts was scuffed with scotchbrite, then blown off with compressed air. I then cleaned each part carefully with Iso, and masked all the areas which i did not want to be the final cockpit color. 

The cockpit colour will only go on the bits you will be able to see when the canopy is open.

Parts ready to go!

I am using Stewart Systems EkoCrylic, in Boulder Grey. I initially mixed up 100grams of Part A, along with 4:1 of flattener. I then added 4:1 Part B and let it sit for 5 minutes, before adding half of the Part B weight in water. 

I sprayed on the first coat as a fog coat, then after around 20 minutes - once the paint was still sticky but there was no transfer onto my glove - i increased the flow a little and started a wet coat. I ran out of paint about half way through the roll-bar on the wet coat, so mixed up another 50grams of Part A as above. It is so hard to guesstimate how much you need on little parts like this. 

I reckon they all came out so nice - no runs anywhere. The colour is deep and the gloss is awesome. The 4:1 flattener gives a nice semi-satin finish. Overall i am very very happy with this paint. 

This is right after spraying - you can see some orange peel. This all totally went away as the paint flowed out and set. 

This is the area where i added the proseal to seal around the aft canopy seal angle and it's flange holes. I think it came out great painted, and i'm glad i did it now before it was installed in the airframe. The remaining sealant will be on the inside of the forward flanges, and i should be able to keep this looking neat by using electrical tape over the flange gaps.

Such a beautiful satin finish using 4:1 flattener

These are actually the side skins for the canopy - i painted the section which may be able to be seen from inside the canopy, just in case.

I then cleco'd on the forward fuselage and roll bar parts - i just had to see it start to look like an aeroplane! Doing it like this will mean a few rivets are not painted in cockpit paint colour, but i don't think this matters. It still looks awesome. I can always touch these rivet heads up with a brush, or perhaps use my airbrush, but i think i will probably just leave them. 

Next up is to rivet all this onto the airframe for the final time. 

37-01 -> 05: Roll Over Bar

Like every chapter, the Roll Bar starts with prepping parts. The roll bars consist of a forward and aft roll bar, which are each split into left/right parts, held together in the centre by a doubler. This needs to be riveted on, to join the left and right halves of the roll bars, before moving onto the rest of the chapter. So i prepped and primed the roll bars and the doublers before riveting them together, then will shoot a second coat of primer over the roll bars where the following steps (ake countersinking) will occur. 

When riveting the roll bars together, the plans have you cleco the roll bars to the fuselage (to the roll bar bases), then set the bottom outer, and centre upper rivets in the roll bar doublers. You can then remove from the aircraft to finish the rivets off. 

I found that there was a bit of stress in the parts, and they were hard to get aligned well on the aircraft (the clecos on the doublers were hard to get in). I had a lot more success with clecoing the roll bars together on the bench, and inserted a bunch of rivets to help with alignment. I then cleco'd the assembly to the aircraft, and set the required rivets, before removing and finishing them off on the bench. 

The parts cleco'd together on the aircraft.

Not aligned very well - the clecos were hard to get in. Not sure why, but alignment was difficult.

I cleco'd together on the bench, then used as many rivets as i could to aid in alignment..

...before clecoing back onto the aircraft, for setting a few of the rivets.

Oh, and this little rivet represented the 20,000th of the project! 

Once the forward and aft roll bars were riveted together, i added some curve to the roll bar splices by rolling it around the edge of the work bench, to assist in getting it to fit. I was then able to slide on the aft roll bar over the top, and cleco both of them to the splices. All holes were then reamed to #30, and the parts pulled apart and deburred. 

The splice rolled roughly to the shape of the roll bar

The splice clecod into position

Half way through the reaming process

Once this was all put back together, i was able to complete the countersinking of the forward roll bar flanges. This is countersunk for AD4 rivets (as the roll bar splices are riveted to the forward roll bar using solid rivets). 

I had to suicide countersink the ones in the corners.

Checking that the countersinks were deep enough to fit the dimples in the roll bar brace.

To countersink the aft roll bar, i clecod on the aft window shim and this gets countersunk to 120 degrees for CS4-4 pull rivets.

On page 37-06, there is one single rivet hole which needs to be countersunk for a CS4-4 flush pull rivet - this sits underneath the plate which holds the bushing for the canopy locking pin. Since i had the countersink cage setup, and was going to prime the outside faces of the roll bar anyway again, i countersunk this hole now. 

Then all the parts were removed, deburred again, cleaned, etched and primed.

The roll bars got a second coat of primer - to make sure all the new countersinks were painted. 

Riveting Together the Roll Bar

The splice strips were riveted to the forward roll bar using sold rivets. I was able to set all of them using the squeezer. 

The locking pin cover plates were installed into the aft roll bar. The forward plates are installed when the roll bars are riveted to the roll bar bases on the aircraft.

The aft roll bar was then installed over the top of the splice strips, and pull rivets were used to attach it. 

The tiny holes remaining in the roll bar splice will be the drilling locations for the aft window, when it gets installed.

Next, i dimpled then riveted on the side brackets to the roll bar brace

The hole in this location is aligned with the centre screw hole for the aft window - so you can get a nut onto the screw. Clever!

Drilling the roll bars to the aircraft

The final step was to slide the roll bars over the roll bar braces - this was initially slightly difficult, until i realised that the splice strips were sitting up slightly and stopping the roll bars sliding all the way down. Fortunately, there is an access area to allow you to later access to the bolt heads at the bottom of the roll bar bases - so you can get a finger in and make sure the splices are sliding down properly. I used a wooden block and a mallet to make sure they were seated, then match drilled the bases. 

This is why you leave out the last few rivets on the tailcone skins waaaaaay back when - so you can pull the skin out of the way to match drill / rivet the roll bars. 

It is starting to look more like an aeroplane and less like a canoe every day!

Once drilled, i removed the roll bar assembly, and deburred all the parts. I diligently made sure to clean up all the swarf! 

 

Before these can be riveted to the fuselage, i need to final paint them in cockpit color - but it is just too cold in the shed at the moment - so they were added to the ever increasing number of parts waiting to be painted before installation.