Category Archives: Fuselage

SkyBolt Install

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Time: 8 Hours

I need to explain to those who are unfamiliar with how the RV-8 has its fiberglass cowl attached to the aluminum fuselage. The stock way of doing this is with piano hinge mated to the aluminum and fiberglass using the center pin to hold both halves tight together. This has worked well on thousands of RV’s out flying. There are challenges to this method, including difficulty getting the pin in and out when removing or replacing the cowl. Especially along the top and bottom of the cowl due to the curve. Another option out there is to use the Skybolt fastening system like many production aircraft. Even the Lear 45 I fly has similar fasteners holding the avionics doors in place. The Skybolt system uses receptacles mated on the fuselage and spring loaded pins mated on the fiberglass. When the two parts are brought together the pins get pushed in and turned to lock into the receptacle. These make installing and removing the cowling incredibly easy and reduce the risk of chipping/scratching the paint that’s usually associated with the hinges. I decided early into my build that I like the look of these fasteners and would use them on my RV-8. So like many projects in the build in order to do one task there are always other tasks that need to be finished first. I started out wanting to seal the firewall inside the baggage area and realized that I needed to have the Skybolt tabs riveted in place first. So that’s what led me to this task. Show my goal was to get The tabs riveted along the top curved edge of the firewall leaving the sides for later. The cowls have two main sections when it comes to the Skybolts, the perimeter of the firewall and to sides of the cowl the run from the nose aft to the firewall. The goal will be for the aft Skybolt of the sides, running from the nose aft to the firewall, will be in sync with the perimeter Skybolts. That way everything looks symmetrical, this will be much easier to show later on in the billed as I get to that stage. But for now I have to do a lot of planning so that that winds up. I will have some lead way in moving the tabs to get that all to work if I leave one or two tabs above the center line open. Those will be able to be moved or spaced so that all line up just right. For now I just need to be close so that a 1/8″ here or there won’t be noticed to get the spacing right. So for now I started working on the tabs which included cleaning up the edges and countersinking the holes that will attach the receptacles.

To start I’m going to center one tab, dead center of the top of the firewall. From there I will work my way outboard until I get to the sides and see how the spacing looks.

As I worked my way outboard I need to find out a rough area for the centerline of the cowl. I got a pretty close location mark with the help of my buddy Glenn. With that mark I was able to figure out the line that would represent the centerline of the Skybolts that will be above the cowl centerline.

With that one tab set I adjusted my spacing on the remaining tabs between this one and the top one to get even spacing. Once I was happy with this I removed the two lower tabs on both sides as I will drill those later. Then I match drilled the tabs with the firewall and forward skin.

I marked each tab with a piece of tape and a number so that I could replace them exactly where they go. After drilling I remove them all and deburred the holes. I also countersunk all the holes on the forward skin for flash rivets. After all the tabs were returned to their correct spots I used my pneumatic squeezer to rivet them all in place. Keep in mind I left the lower couple of rivets on the lowest tabs out so that I could get the next tab in place once I need to. My goal is that I will have some wiggle room up or down with the remaining tabs to get them aligned with the ones that will be on the cowl sides. That way they all look symmetrical. I made quick work of riveting the tabs in place after getting all the holes cleaned up.

After those were finished I moved to the bottom of the firewall. Here there are two small areas that would normally have small hinge sections but will now have two Skybolts.

I added a small piece of .032″ aluminum to the corners to close up the gap that will be between the cowl and firewall. It should also help align everything when installing the cowl. I cleaned up all these holes and got them riveted as well. Slow progress only because I have so little to do and 55 days until I go build my engine.

Wheel Pants Finishing

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Time: 4 Hours

Now that I had the intersection fairing pretty close to perfect I removed them for a light sanding and priming. 

I then removed the wheel pants from the gear and put them back together off the plane. This allowed me to sand all the edges where the two halves meet as they sit on the workbench. I worked the seam with a small file to get a small gap between the two parts that will allow for the paint. After cleaning up the mess I made with all the sanding I put on two coats of smooth prime with sanding in between to fill pin holes. 

Smooth prime works pretty good and is easy to clean up since it’s water based. I cleaned up the pants after the final sanding and applied several coats of filler primer to help reveal any remaining pin holes. 
In between the right and left wheel pants I shot several coats of primer on the canopy skirt after all the work to cover up the rivets. When I was happy with the finish I removed the tape and paper and cleaned off the canopy itself. While I was at it I removed a bunch of the blue protective film from the aft part of the fuselage. 

To help keep any new dust off the RV I put the custom cover on as well as a couple bed sheets I bought from target to cover the tail. 

The right side wheel pant was much worse than the left side with respect to pin holes and surface condition. There are a lot more pits and voids that need to be filled. I did two coats of smooth prime and that took care of most of the pin holes but there are still several deeper pits so I sprayed them with filler primer to better help see those and I filled them with Super Fill. 
After that cures I sanded them and reprimed to call the outsides good, I’ll let the painter fine tune so they come out perfect after paint. I still need to fine tune the wheel opening to have a nice even gap at the front and back of the tire. I also will put several coats of just epoxy to help smooth out the inside surface so dirt doesn’t stick as well. 

I will call these done for now and I’m pretty happy with how they turned out. 

Wheel Pant Intersection Fairings

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Time: 4 Hours

I worked the fairings a little more trying to get the aft edge to sit nice. With these cut as they are scribed from RVBits.com the aft edge sticks out around 3/8″ aft of the gear leg fairing. I didn’t like this look and wanted the aft edge of the two fairings to meet so that it looked like one vertical line from top down to the curve. This causes the aft edge of the intersection fairing to open which I was ok with but I wanted the rest to be tight. You have a couple options from the instructions, one being to use a zip tie through a hole drilled through both sides and zip it tightly closed. The second is a small screw and nut to close it up. I didn’t like the zip tie idea so pondered the screw. What I came up with was to use a nutplate on the inside of the fairing with the threaded part portuding through a drilled hole. This eliminates a need for a nut that looked like an eyesore to me. 

Now I can use a screw that is cut to the perfect length and only have a small bit sticking out and barely noticeable if you really look. Once I was happy with that fit I countersunk all the holes for the tinnerman washers. The epoxy had cured from the holes I filled in the last post so I sanded those down and and drilled for the nutplates that will hold the intersection fairings on. Using the pneumatic squeezed I made quick work of riveting them on. 

While I was already riveting I did the two air valve doors as well but I used blind rivets as they helped my get them to lay flat as I squeezed them as the spring action tried to lift them up. 

I put all the parts in place and attached the intersection fairings and did some final sanding. These things are so nice and thin that I decided to just put a slight bevel along the edge to give a nice clean look. 

So I haven’t decided what if anything I will do with top of the fairing where it splits. I may just leave it and be happy with it. So now I just need to work all the surface of the wheel pants so I can fill pin holes and prime them as well as the fairings. 

Wheel Pant Fairings

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Time: 6 Hours

I sanded the seams of both wheel pants to start the day. I will say that sanding the flox is tough work and it’s is surprising how strong cotton fibers in epoxy gets! My arms and hands are pretty sore, must be cause I’m old! After I had them sanded I put the gear leg fairings back on followed by the wheel pants. Now I started on the intersection fairing that ties the gear leg to the wheel pant. You can make these from scratch or use pre made ones. I opted for the later and bought some from RVBits sold by Cleaveland Tools. These are really nice and have a great shape. You still need to trim them and shape the aft edge based on your needs. My first task was to create a template and mark both side for the shape I wanted. 

Once I had a shape I was happy with I did a rough cut with the band saw. 

Then I slipped them in place and and marked for drill holes. I’m going to do four screws, two forward and two aft. I clamped them in place to check the fit. 

After I was happy and had them marked I drilled through them and the wheel pant and clecko’d them in place. 

I then made the mark for the top aft edge so it meets the gear leg and drew a curve to the very aft tip. With the Dremel I sanded them down and finished with my hands. 

I’m really happy with the shape and fit except the aft seam. It’s going to take a little work to get it to fit nice without clamping them. Overall I’m happy with the look. I will drill and install the four nutplates needed to attach these and screw them down before working on the aft end seam so they will be secure. 

More Wheel Pant Work

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Time: 6 Hours

I repeated the syringe process for the the forward bracket on both sides with the same great results. After those had cured I marked the bottom of the pant for an even edge distance from the tire so that I could trim them. Vans gives you a minimum of 5/8″ space between the tire and the edge of the fiberglass but I have read that you need more like 3/4″ to an inch to allow side loads on the tire which would hit the fiberglass if the gap is too small. 

After getting both trimmed I moved on to the valve stem doors. Normally in order to check the tire pressure or inflate them you would have to remove the forward half of the wheel pants. I decided that I wanted to put in a 1″ doing loaded door so that I could do these tasks with removing a single screw. I ordered mine from Wicks Aircraft Supply but they are available from various shops. I rolled the fuselage around slightly to get the valve stem on the aft side of the tire and at a equal distance from the ground, about 6 1/8″ for mine. I then chocked the tires to hold that position and used my cross hair laser to mark the center of the stem. I then put the pants back on and drilled a hole on the cross hair. After I had the initial hole drilled I removed the pants and opened the hole up to 1″. I tried several different locations on how I wanted the door to swing, as seen with the different drill holes. Not sure why I decided on the top ones but it just looked better to me. 

I used some Super Fill to smooth out the edges of the areas that I built up for the brackets and sanded those after they cured. I also sanded the inside edge where the nutplates would go and riveted them in place.   I also riveted the outboard bracket in place. 

 Now that the nutplates were in place I could put the pants on and have them perfectly in their final place versus with just cleckos which have a little play. 

Now I could work on the seam and the transition between the forward half and the aft half.  After I sanded the edges I added some white electrical tape to the edge of the forward half of the pants so that epoxy/flox won’t stick to that edge. 

I then covered the white tape with clear packing tape. The electrical tape should leave a nice even gap after removed for a nice seam. It will need to be opened up a little down the road by the painter for the paint thickness. I mixed up some epoxy/flox and filled the seam as well as low spots on the aft section of the pants. After curing I will sand the edges down flush to make a nice transition between the two halves. 

In between work on the pants I had added a light layer of epoxy/fairing filler to smooth the transition from the side skirts and the glass I put over the rivets. After that was sanded I put three coats of UV Smooth Prime to fill any pin holes.