New Fuselage Cowl Panels

The sheet metal panels on the forward fuselage were made when we rounded the fuselage.  They weren't in bad shape but new holes were needed for the screws along the firewall.  Also the extension behind the firewall was made as one piece which made it almost impossible to remove.  I decided to split it into 3 pieces.

 I ordered 16 feet of 0.025" 2024-T3 aluminum 4 feet wide from Airparts so I'd have plenty to make all the cowl panels and a mistake or 2.  I don't really have room for a piece that big and I need to cut off a bunch of small pieces.  I decided to try storing it the way they do for rolled aluminum for siding trim work.  That stuff comes rolled in a box and you open a flap along one corner to pull  out what you need as you go.  Airparts shipped the aluminum coiled in a stout corrugated box so it seemed like it would work.

I positioned the coil in the box so the end would come out the corner where the box is joined.  I figured the other corners would be stronger so I'd put the slit in the weak corner.  Even though I only opened one end I reinforced the corner of the other end around the slit with strapping tape.

After cutting the slit in the corner I cut the strap holding the coil tight and taped up the end I opened to keep the box as strong as possible.  This coil has a lot more force than the soft trim aluminum.
With the trim aluminum you just grab the end and pull.  Good luck with this coil.  I didn't want to damage any of the aluminum so I tried pulling the end with the sheet metal pliers.  You just hold your foot against the box and pull.  It works great.

 I don't like to make cuts with snips if I can avoid it.  They just make a mess of the edge.  Instead I rolled the box on it's side so the aluminum lay on the clean, swept floor.  I used a straight edge and knife to score the aluminum.  The Stanley knife did not make a deep enough grove.  The cheap little Plexiglas cutter works great.  You just score it until you can see a good bump on the backside.

 When you have a good score line just fold along the line and break off the piece.  File the edge and you're ready to go.

 This is the panel the windscreen goes on.

I used the original for a pattern.  The screws along the firewall and the fuel tank opening will change.  The rest of the screw and rivet holes stay the same.

 The holes for the cabane struts were originally cut with the panel on the plane, when the biplane wings were built.  I decided to make the new holes just a little more neatly since I was working with a flat piece of aluminum.

 With the old holes drawn on from the old pattern I smoothed the lined and rounded the corners for the new holes.

 The holes were slightly different on each side but the idea is the same.

 I used the nibbler to rough out the holes so it would be easier to clean them up with the files.

To file this floppy piece I placed a board under it supporting each edge as I filed it.

 The old firewall extension was cut into 3 pieces and used as patterns for the 2 side pieces.  I added a tab to the bottom edge to overlap the bottom panel.

 The bottom tab was bent to fit the panel and a flange was bent along the top edge to stiffen the side.  Nut plates will be riveted on for the screws along the top edge.  The nut plates for the lower edge are on the bottom panel.  I overlapped the side panel around the bottom panel because I didn't want rain to run into the bottom panel.

The nutplate holes were located from the top cowl which overlaps the sides.

 I have a venturi to provide vacuum for the Turn and Bank indicator.  It saved me when I got into some fog so I'm keeping it.  The piece of angle allows me to bolt it to the frame at the start of the stringers on the bottom of the fuselage.  The plate is to overlap the lower panel to keep it sealed against fire.

It turned out I needed to make it bigger to work.

 The venturi is at the aft end of the panel The forward end needs to slip on top of the flange on the bottom edge of the firewall.  Those 2 conflict so I added a slot for the panel to slide aft around the venturi, move the forward edge above the lip and then slide it back forward into position.  This meant the piece above the venturi needed to be longer.  I also added more width for some screw to hold it all tight together.

Now you can remove the panel to work on the brake cylinders.

The Engine cowl panels are next.

Windscreen Repairs

The original windscreen was from the front pit of a PT-19.  I think the fuselage it came from once sat near the road going into Owosso, Michigan.  OK, that was over 50 years ago.

You can see it was very low, sort of racy looking.  In fact it was so low Dad hit it pretty hard with his face one day.  Yes, that's Pete Bowers at Rockford 1966.

 The frame got modified.  The base is still the original PT-19 windscreen as are the clamp strips which hold the glass in the frame.  The 2 front corner pieces were cut off and longer ones made to raise the top of the frame.

Over time, the wear of people pulling themselves out by grabbing the top corners of the frame caused the corners to crack badly.  I decided to repair the windscreen before making the new cowl panel under it.

 

I removed the glass and the corner pieces.  I used the corner pieces as patterns for new pieces, which I made from 0.025" 2024-T3 aluminum.

The problem was how to put a nice bend on the corner where the screws go for the glass retainers.  I decided to press the corner into some stiff felt.  I used 2 pieces of 1/4" thick spruce, 1" apart, stuck to a piece of  2" Gorilla Tape to form the die.  The felt was laid on top of the strips.

A piece of 3/8" wide aluminum was used to press the piece into the die.  It worked but I couldn't get the angle I needed.

I moved the wood strips to a 3/4" gap and used a 1/16" strip of rubber, in place of the felt, to protect the aluminum.

That worked to get the needed angle.

The corners were formed to fit just as the originals so they could be riveted to the original holes from the 1967 modifications.

To solve the corner cracking problem I made some corner stiffeners from 0.035" mild steel scraps and welded the corners closed.

I started with a card stock pattern to work out the shape and bend lines.

Each corner is slightly different so patterns and blanks were made to fit each.

I found after my first failed attempt that I needed to bend the front corner angle first and then the other bends to fit.

I left extra metal along the back to trim after bending.

Each bend was marked and then formed using sheet metal pliers.

With the top screw holes added and the back edges trimmed the parts were ready for welding.

The corners were welded, the pieces sand blasted, and painted to match the frame.

I like the industrial look of the rivets and screws left unpainted.

The new Plexiglas panels don't need sealing but if you've ever found yourself flying in light rain it can be real annoying to have water leaking in on you.  The airflow around the windscreen is such that the rain goes over your head and back onto the fuselage.  I used the same seal material I used for the Cessna 140 skylight windows.
I put a strip along the edge of the frame and pressed the glass into it for a tight seal, it's very sticky and soft.

I trimmed any excess from the outside of the glass with a plastic razor blade scraper.

The windscreen ready for the new cowl panel.