Strut cover and wheel well installation

Alright folks - it's finally come time to install the strut cover and wheel well (the NB nose box wheel cover). There's a lot more to it than I originally thought - hence why it's taken me a while to post.

First the strut cover is installed. Then the channel between the strut cover and the wheel well must be prepped and glassed. The NB wheel cover is then bonded in place and the edges around the wheel well is finally glassed.

I should note that I decided to keep the wheel well 'per plans' and did not install wheel well doors. While it might be a pain to retro fit these later on, I'm of the opinion of getting the airplane in the air before I'm too old to enjoy it!

So let's begin... here is the strut cover I had made earlier - in need of a good trim.

My good friend Emmanuel came by to help me out... here we are dry fitting the strut cover and figuring out how the heck we are going to trim it.



We started out by trimming the strut cover's front lip - I made a line to mark where the strut cover had to be trimmed - parallel to the edge of the NG5 strut plate. 

We then trimmed the aft end. It's important to note that the strut cover has a specific fore/aft location - since the flange curvature has to match the bottom lip of the NG30 panels. Here it looks like there is a gap between the strut cover and the F22 bulkhead - but the strut cover was moved aft into its proper location later. Also important to note, the aft end of the strut cover was trimmed at about a 5 to 10 degree angle so that it fit flush against the F22 bulkhead.

With the fore and aft ends trimmed, it was time to trim the side flanges. I simply traced the line parallel with the foam edges.

Once I had my marks, I trimmed the flanges with the bandsaw and test fitted the strut cover once again. Perfect-o! Also, I cut the clearance hole that allows the actuator through. I projected where the hole should go and then slowly opened it bigger - through trial and error until the actuator was able to penetrate through. I then extended and retracted the strut a few times to make sure there was enough clearance.

The strut cover can slide side to side about 1/8". To make sure it would bond in the exact place I wanted, I pre-drilled 4 holes through the strut cover and onto the NG30 panels - making sure there was a 0.25" equally spaced gap between the strut and the cover walls. I then inserted nails to hold it in place. 

Notice the channel between the strut cover and F22 is narrower than the strut cover - this was intentional. It will later be opened up to the correct width after the strut cover is bonded in place.

Before mixing up wet flox, I sanded all the edges smooth and flush..

Baker's zip-lock trick to apply a nice bead of wet flox...

I suppose I could have removed the strut from the fuselage - but I wanted to be able to test fit it in the retracted position just after laying the strut cover down - after cure, there was no going back - so if there were any clearance issues - this was the time to know. In order to keep the strut out of the way, I tied the wheel to my garage roof truss to hold it in the extended position.

Using the nails as locator pins, I positioned the strut cover into place.

 

I noticed the ends required some weights in order to have them 100% flush... here I am poking it...

So I rigged this contraption up... and laid a heavy vice on top of it! It's a 2x4 with two pucks at the ends... pressing the strut cover ends down flush...

Notice how the front has a 2x4 puck that bears all the front weight to the strut cover end...

And the aft puck bears all the back weight to keep the aft strut cover end down flush... cling wrap underneath to keep the puck from bonding to the excess flox..

Taaaa-daaaaa! Strut cover is installed! I extended and retracted the gear a few times to make sure there was proper clearance and that everything had cured right.

Now that the strut cover was on, I had to trim and glass the channel between the strut cover and the F22 bulkhead... notice the black lines on the fuselage belly, aft of the F22 notch...

Also, the wheel well hole needed to be finely trimmed. To assure symmetry, I placed a piece of cardboard over the wheel well opening... went under and traced one side.  

I then cut the cardboard and traced the outline on the mirrored side.

So I have some trimming to do in order to get a perfectly symmetrical wheel well opening...

Hello router...

Here I'm trimming the edges of the channel flush with the strut cover walls.

The router did not allow enough depth to get to the other glass surface. Notice the glass lip that still needs to be trimmed flush with the rest of the wheel well opening...

So I flipped the fuselage right-side-up and used the router to trim it flush...

I then sanded the surfaces that were going to mate with the NB wheel cover...

I put the NB wheel box in place and inserted a scrap piece of foam to keep it stretched open - and hence proper dimension.

When I was happy with its placement, I pre-drilled holes and inserted nails to keep everything in place.

Before bonding the wheel well, I retracted the gear and made sure everything cleared.

With all systems being a go, I mixed up wet flox...

I then installed the NB wheel box in place using the nails as locator pins. I then added a bunch of 2x4 pucks around the flange and a bunch of small heavy items on top of the pucks to keep the NB wheel well flanges flush with the floor.

I then crawled under the fuselage and cleaned up any excess flox...

After cure, I flipped the fuselage up-side-down and went on to work on the channel between strut cover and the F22 notch.

I used a dremel to trim the channel roof so that it created a nice transition from channel to NB wheel cover.

The channel walls had already been cut to proper width... but I wanted to do something about the step between the strut cover and the F22 notch...

So I created a ramp out of urethane foam. I inserted a block inside...

And sanded away until I got a nice transitional ramp between strut cover and F22 channel..



Emmanuel helped me sand the top edges round - so they would transition smoothly between strut cover corners and channel corners...

See how the top corners now transition nice and smoooooth?

Ok... so now we are ready to glass the channel... I started out by sanding all mating surfaces smooth and applied plain epoxy to everything...

I then covered the urethane ramp with micro slurry...

And tucked that sucker in there!

I then mixed up flox and applied it to all corners and transition edges...

I prepregged 2 plies of BID and positioned it in place.. it took a while to remove air bubbles..

The strut cover and aft channel in perfect harmony...

After cure, I trimmed and sanded things smooth... I could have used peel ply but I figured it wouldn't have liked the sharp corners and tight radii...

So close.. almost there! Now to glass the foam around the wheel well edges...

A flox corner is needed all around the wheel well bottom edge. So I started out by cutting out a groove with the dremel...

And then used a metal file to sand the glass edge. This is very important to do to make sure the flox will bond properly with the glass.

The metal file makes sure you have a pure glass mating surface instead of mating with speckles of leftover foam...

Going ALL around...

Even the edges that the glass will come in contact with the channel need to be prepped...

Now that is one groovy groove! ::ok, cheesy joke!::

Ok, I think we are ready for flox! I sanded all mating surfaces...

Wait, one more thing - I added masking tape so excess flox or resin would not bond to the NB wheel cover...

First, I slurried the foam...

I then mixed up flox and applied it all around...

I also added flox to transition between foam and NB wheel cover - hence the two-layer flox bead...

I then prepregged 2 plies of BID and tapped it into position... cutting the edges to proper length...

I removed the cling wrap and removed air bubbles by hand...

I made sure the flox corners made good contact with the wet glass prepreg.

And then the other side...

Voila!! I then trimmed the top skirt so that it would not fall under its own weight and ruin the flox corner.

I let it cure overnight...

After a full cure, I trimmed the skirt using the multitool...

Then a razor blade to get closer...

And then sanded the surface flush...

Daaaaamn that is a nice wheel well! It actually looks pretty sloppy in the picture... but you just wait till after finishing and painting!

Testing the retract again... looking good!

I'll add the plexiglass window (through the instrument panel) later on. Also, there is some feathering work that takes place during finishing to reduce air separation aft of the wheel well.