Category: Longerons

While I wait for the centre fuselage parts to dry I decided to skip ahead a little today and get the longerons down. To fit them to the fuselage first they need to be notched to fit around the vertical bars at the back of the fuselage.

Given the amount of work that’s already gone into the longerons this is one scary task so I decided to really slow down and take my time. Preperation started last night by reading the manual, studying the drawings and research others’ builder logs.

This morning I felt confident enough to give it a go.

Having read the other build logs I knew that the longerons may not fit in the bulkhead cut outs so first task of the day was to check with a scrap piece of angle. As expected it didn’t fit so I filed the notches a little to make room.

After all 6 notches were done I set up the longerons on the benches and clamped the aft deck in place as per the drawings and triple checked the measurements and orientation.

Once I was satisfied that it was correct I marked the notch.

Then I removed the deck and drilled two 3/32 holes and cut the notch with a hacksaw.

After several iterations of trial and error I finally had a nice fit around the vertical bar. I double checked it was correct by fitting it to the fuselage and popped on the aft deck too.

I’m pleased with that! So I fitted both longerons and flipped the fuselage over ready for the centre fuselage when that’s done.

Next was a little bit of workshop re-organising. While searching for the aft deck earlier I realised that the huge fuselage crate was taking up a lot of room in the workshop unnecessarily so I relocated the few parts that were left in there and removed it from the workshop. I also took some time to finish packing away some of the hardware. After an hour or so of sorting out nuts and bolts I still had a bench load of stuff left to pack away!

That’s for another day though.

Just one task today and that was to trim the aft end of the J-Stiffeners as per the plans. I pretty much followed what other builders logs did here and drilled a 1/4″ hole and then cut with the dremel. Then I filed it all to final shape.

The next task on the longerons is drilling the aft canopy deck to the longerons. This involved placing the deck on the 28 1/4 mark and making sure the longeron bend matched the curve of the deck. It did so I clamped it in place with lots of clamps then drilled it in place.

Once both longerons were drilled to their decks I then had to find a place to store them for a while. I chose to rest them above the wings where they are out of the way and safe.

Lastly for today, I found the J Stiffeners and cut them to the 3 different lengths on the plans.

That’s all for today.

Helpfully, Vans provide a full scale template of the curve/bend required and suggest making a cardboard template for accuracy. To be honest, I’ve never had much joy with the accuracy of cardboard templates but luckily I had a bit of 4mm plywood lying around so I decided to use that instead. I cut out the paper template and stuck it to the plywood. Then, using a stanley knife with new blade, I carefully followed the curve of the paper template. I repeated the cut numerous times until I cut through the plywood and had a nice template.

Earlier in the week a very kind RV builder offered to lend me their bending dies which involved a quick trip over to Wycombe airfield to collect them and swoon at their flying RV. With that in hand I felt quietly confident about getting these bends done.

The first problem I encountered however is that the longerons wouldn’t fit in the vise because various items on the workbench were in the way. I decided to relocate the vise to the portable workbench instead. Once there I then sat the dies in the vise but found that they would sink to the bottom of the vise and be tricky to keep in place. I popped a piece of wood below the dies and it was problem solved.

I then put the longerons in the dies in the vise and set about squeezing the vise until I could feel the dies touch the longerong and the felt it bend slightly. On first attempt it was clear I didn’t bend it enough. So on the second round I added another 1/4 turn of the vise handle. Unfortunately that was too much and I over bent the longeron. Not a problem as it is easily unbent by gripping it in the vise and unbending by hand. Eventually the bend matched the template perfectly.

Once the curve was bent it was time to do the sharp downward bend. This was a lot more draconian and involved clamping the longeron in the vise and whacking it with the mallet several times. Nothing too difficult though but it did make everything on the workbench ‘dance’! The last task was to twist the sharp bend so the end of the longeron was at 17 degrees. I used a large wrench to make the twist without any difficulty.

After lunch my wife joined me to help bend the right longeron. It is amazing how much easier (and more fun) it was with an extra pair of hands.

That’s two longerons bent! I’m not 100% confident that all the angles are perfect but it was pushing 30 degrees in the workshop and I was losing motivation fast. Time to stop for the day before I make a silly mistake. I popped them on the floor before I left to avoid any silly accidents overnight.

Not bad for a days work, but I think it does need another check.

I couldn’t put it off any longer, those longerons needed to by cut. I brought home another tape measure from work to make sure sure sure there was no mistake. I also recruited my son to come and double check the plans and the measurement marks.

While reading one of the builders blogs earlier in the week I noticed they had a small chop saw so I couldn’t resist and treated myself to one too. I am delighted I did, it arrived perfectly set up and cut through the longeron like butter. I’m very pleased with it.

Once cut I checked the measurement again…

I’m pleased with the cut, a bit of filing will trim that to perfection but I’ll wait until much later in the project to do that. Next I marked the longerons for left and right and forward too. Then I trimmed the aft ends of the longerons as per the plans.

Finally I marked the bend location along with marks at every inch to help with the bending process.

That’s all for today. I’ll do the bend another time.

The bulkhead parts are still drying so I can’t do any work on those today so I decided to locate the long angles that were shipped with the wings and dust them off. The instructions say to cut the longerons to exactly 173 7/16″. I measured the longerons and marked it then checked again with 2 different tape measures to be sure. I then left it at that for the night. There is no way I want to make a silly mistake on these as it would be a nightmare to get replacements.