Notes About Making the Fiberglass Windshield Fairing

Source: 2026 Issue 1 Beartracks, David Kragnes

Finally got to windshield install. Thought I might have some tips.
I have built 3 boats, don’t ask why I spent time on something that doesn’t fly, so when I got to the lay up of the windshield faring I thought I might have some worthwhile tips. The plans lay out good advice for prep of the windshield and cowling. 
I have used System Three so my thoughts focus on that type of epoxy. I believe West Systems behaves much the same. Once you have the windshield in place and the area taped and waxed, mix up about 1/5 cup of epoxy, the bottom 1/3 of an empty beverage can is the perfect mixing cup, plan ahead you don’t want to have to stop the process to empty more mixing cups, have the cut cloth strips and a 1 inch stiff bristle brush ready. Wear rubber disposable gloves. 
You don’t need to make a big mess. Lightly paint epoxy down the center of the area, press the first layer of dry cloth on the damp surface then use the stiff brush to stipple, dab a little at a time, epoxy into the cloth only wetting till it is clear. You want to see the weave. Remember the cloth is the strength so keep it as dry as you can and have the cloth turn clear. Now in a 70ish degree shop wait 2 hours. You can save the brush in a can soaking in MEK. 
Mix the next batch and repeat. Inside a day the epoxy will bond and letting it set a little will make the next layer easier. If you catch it just as it is firm but tacky, shop temperature will dictate the time. the next layer will stick nicely in place for you to stipple. Dry is good but cloth should go clear with no bubbles underneath, again being in the right time frame makes it easier as you can push down a bump if it is cottage cheese or so consistency. Start early in a day and this will all time out nicely. 
When you are happy with the number of layers again give it a couple hours. Now since you have been a good craftsman the last layer looks like you can see the weave, as you start sanding you don’t want the first thing cut to be the cloth (reducing strength), so mix a little epoxy with thickener, micro balloons or wood flour, till you have thin peanut butter, and paint a nice smooth finish on the surface. This will give a nice layer to do less sanding on. 

Making the Windshield Lower Fairing Strip

Because of variations from builder to builder, if Bearhawk Aircraft were to provide the lower windshield fairing, it probably wouldn’t fit well. For that reason, it’s best if each builder fabricates his own.
If you’re a sheet metal guy with shrinkers and stretchers, you can make this out of aluminum, but most will find it much easier, if a little messy, to make this out of fiberglass right on the airplane.
If you’ve never used fiberglass, it’s easy to learn. Go down to your local boat shop and pick up some fine-weave cloth and a slow-setting epoxy mix. If they have the glass in four-inch strips, that’s what you’ll want. Also round up a box of nitrile gloves, a roll or two of clear packing tape, disposable paper cups and sticks for mixing, a disposable bristle brush, squeegee (old credit cards work great), and some wax or mold release. The first step in the process is to cover every bit of the airplane and the floor within three or four feet of the windshield with protective sheeting because you’re going to make a terrific mess.
To keep the fiberglass from sticking to the fuselage or windshield, everything should be liberally coated with mold release (automotive wax will work). Mask the boot cowl and windshield with tape (electrical, packing tape, etc) and then wax that tape. Apply at least one layer of the tape perpendicular to the joint between the windshield and boot cowl, and it will bridge gaps at the bottom of the windshield and make a smoother intersection in that area, which will make your life easier, when putting the fiberglass strips in place.

Set up a piece of plywood on some saw horses close to where you’ll be working as a temporary work surface and cover it with polypropylene sheeting (or a trash bag, or wax paper). Stretch it tight and staple it so it won’t move while you’re working on it.
You’re going to use this surface to stretch your glass strips out on and soak them prior to laying them up on the windshield. Depending on the thickness of the cloth you’re using, you’ll be laying up a minimum of six layers with seven to ten being better.
You’ll need help doing this, or you’ll make even a bigger mess than normal. Lay out enough strips to make ten layers and make them at least six inches longer than needed so you don’t have to worry about positioning. You’re going to be doing a lot of trimming and sanding after it cures, so better to have too much. Mix up more resin then you think you can possible use because you definitely don’t want to run short. Using a stiff brush, saturate each of the strips. You’ll see the strip go transparent as it becomes thoroughly wet. We do it this way because the working time of the epoxy is longer when spread out in the strips. When it is in the cup, the mixture will start to warm itself, leading to a faster cure time.
Have your helper grab one end of a piece and the two of you walk it over the nose and lay it in place around the bottom of the windshield. Press it down and use a small squeegee to get any bubbles out.
Keep laying strips on top of one another, trying to keep the edges even and the strips centered. However, it isn’t critical they be perfect because you’ll be sanding later. What is critical is that you try to squeegee out as much resin as you can from each layer and make sure there are no bubbles or dry spots, as indicated by white areas. Pay particular attention to the bottom, rear corners and you may want to cut some short strips and widen out the ends to cover the gaps. If in doubt, make the fairing larger than necessary, since you can always cut it off later.
When everything has cured, but before removing it, run masking tape from side to side on the fairing that indicates where you’ll trim it. Then carefully mark the edges of the tape so you have straight lines from end to end to trim to. From this point on it is more body work than airplane work. Use a lightweight, non-shrinking filler like Polyfiber Superfil. Avoid automotive fillers like Bondo, which are too heavy. A good filler will sand easily. Use a compatible filler- if you used epoxy in the fiberglass, you’ll have to use epoxy-based filler. If polester vinyl resin is used, you can use a filler based on epoxy or vinyl-ester. When the unit is all finished, you’ll want to mount it to the boot cowl with #8 screws, using nut plates under the aluminum. Don’t drill any holes from the fairing into the windshield.
Laying the soaked cloth strips in position is messy and needs two sets of hands. Cover everything in sight to protect it. The material will stretch and conform but be sure to roll out any bubbles and excess resin.
Trim the edges then sand and fill as if you’re doing sheetrock or automotive body work.

Installing the Instrument Panel

Bolting it in place
The kit has a number of tabs welded across the tubing at the panel station. These tabs should be bumped back slightly to allow you to install the panel with a slight upward facing angle. 7 degrees seems to be a good compromise, and artificial horizons and direction gyros are available for that angle mounting. Use #8 screws through those tabs, but since they are so accessible, plain hex nuts will work fine behind the panel. The bigger tabs in the middle are for the throttle and prop controls.
Securing the top of the panel
If you extended the top of your boot cowl aft, be sure to pad the sharp edge with something like split automotive fuel line. This is essential to protect your face in case of a sudden deceleration.
You’ll need to have some sort of angle at the top of the panel where it meets the boot cowl. If you have access to a metal shrinker, use it to match the curve of the instrument panel. It is also perfectly acceptable to bend a few .032 angles and spread them around the curve. Use countersunk #6 screws with nut plates on one side of the angle, and rivet the other with flush rivets.

It will be easier to cut out the instrument panel blank before you permanently install it. Several providers offer services for CNC-cut panels, and many builders find those services to be a good value. You’ll be spending a lot of time looking at the panel, so careful craftsmanship is crucial. If you’ll be cutting your own panel, this means slow going with shears, a die grinder, and a file. Consider that a CNC-cut panel might save several days of work.
As you locate your panel equipment, be sure to allow clearance for the welded tabs and the tube at the bottom of the panel, and for the attaching angle at the top. For large EFIS screens and radios, install doubling angles to stiffen the panel. Long, heavy radios will require support on their forward ends (back of the radio).
From the human factors standpoint, switches that are spread around the panel in clumps will be easier to locate than switches installed all in a row. Peel and stick label machines are great for temporary or long term labels. Keep in mind that you might want to change your labels after the first few hours of flight testing.
When it comes to instrument panel electronics, the best advice we can give is to wait until the last possible moment to buy them. The technology is changing fast, and an expensive purchase this year will only spend time aging while you finish the rest of your construction. If your avionics are installed in racks, see if you can purchase the racks in advance, so that you can just slide the expensive part in later.
If you’ll be installing traditional round instruments, buy or borrow a locating template, and ideally, a punch. You can cut round holes with a circle cutter mounted in a drill press, but be very careful not to get your fingers caught in it. And no matter how tempting it may be, never try to use one of these cutters in a hand-held drill motor. Test your method on scrap material before you try it on the panel blank.
The Matco type of punch is more expensive but an absolutely fool proof way of cutting a perfect instrument hole.
A fly-cutter allows flexibility in the size of the hole, but you have to be precise, when setting it up for instruments. Also, all work must be done in a drill press.
The hand nibbler is a simple tool that will let you cut square holes and edges in aluminum with ease and virtually no distortion.
When it comes to cutting square holes, first mark a layout with a super fine-point felt tip marker. Drill a hole at each corner with a 1/8” bit, set 1/16” inside of the final line so that the final line will be tangent to the drilled hole. Next, drill a hole (or series of holes) in the middle so that you can get your cutting tool into the piece. Cut increasingly larger pieces out of the middle, and as you get to within 1/16” or so from the final line, use a file. Be careful not to cut a square corner with the file where you drilled the original 1/8” hole, since that would create a stress riser. Note that with shears, if you cut too much material off in one pass, you’ll be more likely to get distortion in the good piece. Remove less material with each pass as you approach the final line.

Installing the Firewall

The firewall is attached with the mounting flange extending forward. First, run a 3/8” drill bit or reamer through the five bushings on the fuselage. They are slightly undersized and may have weld scale inside of them. Do the same thing on the engine mount. Don’t let the drill move around and wallow out the holes. There are pilot holes in the firewall for the top two holes, but before drilling anything in the firewall itself, be aware that it is stainless steel, which is quite hard. The key to drilling it is to use high quality drill bits, and keep them cool.
Verify firewall’s position before drilling the holes, ensuring that the firewall is centered on the fuselage left to right, and the vertical centerline of the firewall is parallel to the vertical centerline of the fuselage.
Drill out one of the top holes, then slide a bolt through the mount, the firewall, and the appropriate fuselage bushing. Then clamp the firewall in place with the other pilot hole centered in the other top bushing and drill it out. Run bolts through both holes and use them to index the firewall in position while you drill the other three holes.
Next, drill the 3/16” holes for the steel tabs. Center punch each of the mounting tabs from the cabin side, and drill the tab and the firewall at the same time, with the drill on the cabin side of the firewall. Enlist some help to push on the other side of the firewall with a block of wood to keep it from flexing. Cleco these holes as you go. When you are ready to attach the firewall permanently, use AN3 bolts.
You can put Nyloc nuts on the back side, or mount nut plates in the tabs. Don’t use sheet metal screws or Tinnerman nuts unless the Tinnermans are for machine screws (Monadnocks). If you want to install firewall insulation, do it now and don’t bolt through it. Cut out the insulation for the tabs so there is metal-to-metal contact between the fuselage steel and the firewall.

Installing the Boot Cowl

Before we get started on installing the boot cowl, let’s talk about the overall concept and what we’re trying to accomplish. The boot cowl is the band of metal that wraps around the fuselage, just behind the removable cowl. It connects the firewall to the instrument panel, providing a base to mount the windshield to, and gives the firewall flange support so that the cowling can be cantilevered out to the prop flange. Most of the boot cowl’s circumference is made from 2024-T3 aluminum, though the bottom center section is made of stainless. While it isn’t a particularly complicated structure, it is going to take some thinking to understand all the various aspects of it. The boot cowl can be attached with screws, or permanently riveted in place. In both methods, make provisions to access the bottom area for inspection.

Your exact firewall location, fore and aft, may change depending on how you install it, so you’ll have to do a little fitting of the sheet metal. The sheet metal pieces for the sides and top of the boot cowl in the kit are cut oversize, fore and aft, to allow for trimming to an exact fit. Once everything is together, you’ll need to trim them. There are some differences between boot cowl installation on the kits and that which Bob outlines in Beartracks, so this is a rare case where kit manual guidance will supersede plans/Beartracks guidance.

Here is the sequence of events necessary for installing the boot cowl, assuming the firewall is already fastened in place. The underlying concept is that you’ll need to build up all of the parts that the boot cowl is attached to, then you’ll connect those points with aluminum sheets and the stainless tunnel.
1. Position the Station B Bulkhead. This is the piece that the back of the stainless tunnel attaches to on the belly. It is shaped like a trapezoid, and is about 3 inches tall and as wide as the fuselage. If your kit doesn’t have tabs on the Station B tubing (very unlikely), install the floorboards across Station B, so that you can attach the bulkhead to the floorboards. On most kits there are tabs on the front of the Station “B” tubing to which the bulkhead mounts so the floorboards do not need to be in position. Mount the bulkhead to the tabs, with top flange facing back, and the bottom flange facing forward. There have been some changes to the configuration of this bulkhead over the years. The bulkhead can go in front of or behind the tubing at station B. Use what works best with your combination of tabs, and if it isn’t making sense, please contact Bearhawk Aircraft for clarification.
2. Position the Stainless Tunnel. Cleco the formed stainless steel tunnel flush w/front of firewall. It goes on the outside (bottom) of firewall cut out flange. In some instances, it may fit better on the inside (top of the firewall cut-out flange), which is preferred. You’ll get a better fit if you snip the corners of the firewall flange so the center portion can be bent down to match the slope of the tunnel. Before snipping it, drill a 1/8” hole in the corner and snip to the hole so there is a relief radius in the corner to prevent cracking. The front of the tunnel must be trimmed so it is the same angle as the firewall. The rear lip of the tunnel goes on the bottom (outside) of the rear bulkhead flange.
3.Install the Instrument Panel. Around the top of the boot cowl, the boot cowl pieces will go from the top of the firewall to the top of the instrument panel.
4. Install the Fuselage Side Formers. Early kits used welded steel formers to shape the boot cowl at the front of the door openings. Later kits use aluminum pieces that are attached to welded tabs on the fuselage. This simplifies fabrication, and also provides better opportunity for corrosion protection, by eliminating nooks and crannies that are hard to paint.
5. Fabricate the Boot Cowl Top. The top of the boot cowl is going to be the hardest to make, because it must allow for the big diagonal steel tubes (cabanes). There will be a seam in the panel somewhere, either forward of the cabanes or behind them. If you allow for the seam aft of the cabanes, then you’ll have no seam to seal to the elements. The windshield geometry leaves about three inches of boot cowl exposed between the windshield and the cowling, so a seam aft of the cabanes will fall inside the cabin. A seam forward of the cabanes will be outside of the cabin. Start with poster-board and make a pattern that goes from the top of the instrument panel to the top of the firewall. If you make the seam on the aft side of the cabanes, you might as well make a removable access panel that will allow service to the top of the instruments. For this, cut a 15” wide panel out of the centerpiece that goes from the top of the instrument panel forward to the tubing “V”. This panel will attach to the instrument panel top flange on the aft side, and will attach to the remaining boot cowl sheet along its sides. Either rivet a strip and butt the edges of the panel and the boot cowl, or overlap the sides of the panel over the boot cowl. Make these panels out of poster board to allow for careful fitting around the cabanes, and then copy those patterns onto aluminum sheet. If you are planning to have this panel overhang the instrument panel as a glare shield, leave enough extra length so that you can pad the sharp edge. Cut the sheets to shape, and install them with clecos through the firewall flange and instrument panel flange, eventually using #8 screws or 1/8″ rivets at 3 inch spacing.
6. Make the Boot Cowl Sides. Now that the stainless tunnel and the boot cowl top are in place, we’ll connect the two with boot cowl side panels. Use side clamp clecos to get the sheets close to their final location, and then trim the top of the side sheet so that it has a 1” overlap with the boot cowl top section. Use clecos to match drill the boot cowl top and sides at 3 inch spacing for screws or rivets. Once the boot cowl side is attached to the boot cowl top, wrap the side around toward the tunnel and match drill the boot cowl side to the instrument panel flange and the firewall flange with 3 inch spacing. The side will stop approximately 5 inches from the tunnel, allowing for an access panel. Beartracks shows breaking the top end of the side pieces 90 degrees before riveting them to the middle piece to stiffen it. This is not necessary and the supplied side pieces aren’t long enough to allow for that. If you desire stiffening in that area, break a piece of .032 or .025 into a 3/4” angle and rivet it in with the same rivets used to join the center piece with the side pieces.
7. Create the Lower Access Panel. The side pieces won’t meet the tunnel at the bottom. They will be short of the tunnel by about 5”, which is intentional as inspection panels will fill the gap. Find the bottom access panels provided in the kit to cover the openings on each side of tunnel. They overlap the sides about 3/4” inch. Get them in position, drill and cleco, but, when drilling, give some consideration about the location of the nut plates that will eventually hold these panels in place. The forward edge of these panels will be held in place by the fasteners that hold on the cowling. These small bottom panels are designed to be removable so install nut plates on the inside of the bottom edge of the boot cowl side skin. Also put nutplates on the inside of the tunnel flange lined up with the holes drilled in the last step. Sheet metal screws and Tinnermans are also acceptable. You’ll want to take those panels off when doing annual inspections. Break the edges to form a 1/4”, 5° lip.
8. Rivet or bolt boot cowl sides to firewall and door frame formers.
Aft of the tunnel on the belly, there is an aluminum sheet piece that extends to the front stringer bulkhead at Station C. This gives you a place to mount shock strut seals. When fitting this piece around the shock struts, leave room for movement of the struts, as depicted in the linked article. The piece will also need to have two slight bends in it to make it line up with the stringers and the tunnel bulkhead. Locate these bends by temporarily clamping the sheet in place. Make marks where the stringers hit it at the rear and where it intersects the center two bends in the tunnel bulkhead. Connect these two marks with slight bends (approximately 15 degrees), being mindful of the bend radius. You can attach the sides of this piece with un-padded Adel clamps along the longerons. It can also be attached to the optional side panels that go under the front doors.
The plans don’t address any aluminum side panels that cover the fuselage area under the door sills and above the landing gear and wing strut, but these side panels give a convenient place to attach strut and landing gear fairings and make a good transition from the side to the sheet metal on the bottom.
To protect the fabric where it wraps around the door sills from people getting in and out, fabricate a “scuff shield” of .016 stainless or .025 aluminum. It will be an angle as wide as the door sills that laps over the outside and has a 3/4” lip facing down. This not only protects the fabric but also forms a convenient place to attach the metal side panels to. To attach the top edges of the side panels to the scuff shields, nut plates on the back side of the side panels are preferable, but Tinnermans will work fine.
Where the side panels under the doors meet the lower longerons, leave them long enough to wrap around the longerons and continue 3/4” under the belly to attach the belly aluminum to. To make a smooth transition around the longeron, after the metal is bolted in place but still unbent, form the aluminum around the longeron by running a block of wood back and forth along the longeron to gradually force the aluminum around the corner.
Space Adel clamps along the bottom longeron with their legs laying horizontal and facing inward. Fasten both the bottoms of the side panels and the ends of the belly panel to these Adels.
To make an aft attachment for the lower side panels, use unpadded Adel clamps to attach a 3/4” hardware store aluminum angle between the longeron and the door sill. This angle should lay right under the back edge of the aluminum side panel. It will need to be notched to go over a diagonal tube mid-way up.
Have the “L” of the angle oriented so the open edge faces back so the fabric can wrap around the other side. Install nut plates on that piece of angle to accept screws through the side panels. The fabric will wrap around the angle and continue no further.


The bottom panel that goes from the landing gear shock strut to the side of the fuselage. The top hole is for the shock strut, the bottom left for the landing gear fitting, and the lower right cut for the rear landing gear fitting and lift strut. The break in the surface is not as severe as it appears. It is a slight crease to line up with the belly stringers.

October 2018 Addition from builder Dave B. in Edmonds, WA:
I opted for #6 screws and nut plates all around, more than strong enough and allow easy removal of panels in the future. I ended up not using the top panel provided with the kit as I wanted a larger opening to access the back of the instrument panel, the access panel I made is about 24″ wide and runs almost to the windshield. Contrary to the manual I started with the side panels since they would be lapped by the top panels and once I had them secured I trimmed to make the top opening symmetric about the aircraft CL.

I’d read several posts about either breaking the edge of the top of the side panels or installing some angle for stiffness, but I found once everything is buttoned up there didn’t seem to be a need. No discernible flex when I reef on the instrument panel and everything is rock solid. If I notice any pillowing as I load up the instrument panel I can always add some supports but I don’t see that being necessary.

One thing that made this particularly fun was the fact the plane made by the front of the firewall flange isn’t planar and varies +/- 1/16″ or so when measured against the instrument panel. Nothing on a welded frame this size is perfectly symmetric so don’t count on that… I also created quite a problem for myself and had to remake the starboard boot cowl extension panel because I allowed the firewall in that area to get kicked forward about 1/4″ when I match drilled everything. I ended up putting bolts and washers through the motor mounts to suck the firewall tight against the frame and secure it while I wrapped the rest of the boot cowl and it was all good after that.

Some final cleanup to do before paint but I’m done working these for a while. With the instrument panel in place I can finally start cutting and mounting some racks.

Dave mounted an optional bell fairing at the bottom of the firewall to help promote cooling airflow. Several builders have reported that this works well.

Bob’s Method for Boot Cowl Fabrication

Source: 1998 Beartracks, Bob Barrows

The boot cowl is the sheet metal installed on the fuselage from the firewall back to the instrument panel and station P-B.

We use .025 2024T3 Alclad for the top and side sections an .032 5052H-32 for the bottom section which is called the tunnel.

The tunnel serves two functions – both to act as the bottom skin of the boot cowl and to allow an efficient flow path for the exhaust cooling air from the engine.

Install the firewall and the instrument panel before beginning the boot cowl or the tunnel.

The tunnel is made to fit between the firewall cutout (see drawing #18) and the T3 former shown on drawing 16 Sta B-P. Tabs are welded on this former in about 8 locations as needed to attach the tunnel and the cowl side skin that wrap down around the bottom of the fuselage to meet the tunnel.

The boot cowl and tunnel are held in place by using plate nuts (#6 or #8) and screws. Clip or Tinnerman Nuts and screws were used to attach at station B-P .032 side formers (see drawing #16). Use a 3″ spacing on your screws.

Making The Tunnel

This part is somewhat difficult to make, I usually have to do it twice before I get a good one.

You will need to use a bending brake, a hand seamer and some method to shrink the back edge a little. First bend as shown using a bending brake.

The side skins are attached to the tunnel as shown below.

The top skins are attached to the side skins as shown below.

The top skin is approximately 28″ wide across the top of the firewall and at the instrument panel.

Dimple the top and side skins and use flush head screws to attach to the firewall.

Holes are cut in the top skin to accommodate the T14 fuselage tubes. The skin is slit from these holes to the firewall to allow for installation.