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  • Fiberglass windscreen fairing

    I glassed the windshield fairing today. A few have posted questions about what to use. For anybody who has fiberglassed before, you won't learn anything here.
    For those who haven't, I will tell you what I bought, and how I did it. Most of it I already had, but I did buy a roll of fiberglass from ACS.

    First you have to get the windshield in the correct orientation. I won't go into that because each will be slightly different. Heat molded plastic on a heated welded fuselage. There will be some variation.

    I used 2" blue masking tape, some PVA mold release (car wax will work), 4" fiberglass tape from ACS (very good quality), and Aeropoxy, although most any brand of laminating resin will work. Polyester resin would also work, and is cheaper. By the time you get the correct ratio for a long working time you might have wasted enough glass and resin that epoxy might have been cheaper. Use "slow" hardener as this will take a while and it is best to do it in one go. Not one batch of epoxy, I used 4 batches. But just keep laminating until you are done. It will come out better, and you will only make a mess one time. I use cheap plastic cups, but if you are only doing one job, you might want to splurge and get the fancy cups with the measurements printed on the cup. You won't need a lot of them. I use plastic silverware for mixing, and the cheapest disposable small paint brushes I can find. I use "plumbers" rosin brushes.

    Old cloths, disposable gloves, sharp scissors, acetone and paper towel should be kept handy. Clean the scissors at the end with acetone.

    I coated the windscreen and boot cowl with masking tape. 70% was very easy. As you go farther aft, the windscreen pulls away from the boot cowl. You will use the tape to bridge the gap. The tape becomes a "mold". You want it to look good. See the picture where the ruler shows a straight line from the windscreen to the boot cowl. You are going to look at this every time you go flying.

    I drew a black magic marker around the approximate width of the finished fairing and made sure I covered it up. I will trim it and grind it to shape later. Don't make it too small.

    Wax the "mold" so the glass won't stick. Let it dry. I cut the fiberglass tape into 18", 24" and 30' inch strips. Enough for 10 layers. I overlap at least a 1/2", and I stagger the overlaps at random. If you put the overlaps all in one place it will be twice as thick there.

    I make up about 6 ounces of resin at a time, and keep making it until I was done.

  • #2
    Here are more pics. My fairing will be almost 4" high at the aft edges, and 1" at the middle of the cowling. That 1" was the minimum I wanted for the lower bevel for the fairing and was one of my limitations in locating the windscreen on the cowling. I will use either 1" or 1 1/4 inch of fiberglass on the windscreen. I will try to make it exactly the same measurement all the way around.

    So in the middle of the cowling, my fairing will be 1" x 1", and I will try to make a nice transition to a bit under 4" at the rear. A few of the BH videos on youtube have good examples of how they will look. You also have to plan the transition to how this fiberglass fairing will mate up with the metal strip/angle that bolts thru the windscreen to the fuselage tabs. Rollies BH 5 fairing goes over the top of the metal strip. Mine will butt up against it, edge to edge.

    I will remove it tomorrow and post pics.

    Fiberglassing like this probably takes less skill than most other things. But for most kit builders this is probably the only fiberglassing they will do on the BH.

    Comment


    • #3
      I like to cover a small table or surface with wax paper. And wet out the cut strips of fiberglass cloth laying flat on the table. The wet out strips of cloth take a lot longer to for the epoxy to get hot and go off. Mark

      Comment


      • svyolo
        svyolo commented
        Editing a comment
        If the temp was a little warmer, I probably would have resorted to that. I use slow hardener, and temp was only about 60 F. It has been a long time, but I have seen epoxy start on fire. Getting it out of the cup, and increasing the surface area definitely keeps it from "going off". I only mix up a little at at time.

    • #4
      Thanks for the great write up... one of those things to put in beartracks

      The wing strut fairings are those offered by the factory or is it a custom fabrication also... or are those parts borrowed from other planes
      ..................
      i did a quick search and the wing strut fairings are offered by the factory at very reasonable prices
      Last edited by way_up_north; 07-07-2020, 01:40 PM.

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      • #5
        Those fairings are pretty repeatable and can be mass produced and trimmed to fit. I am not sure the same can be said of the windscreen. Too many variables.

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        • #6
          Originally posted by svyolo View Post
          Those fairings are pretty repeatable and can be mass produced and trimmed to fit. I am not sure the same can be said of the windscreen. Too many variables.
          I edited my post to clarify I was only talking about the wing strut fairing...i and other builders really appreciate a post like yours... especially when it comes to finishing...it’s a great step by step post
          Last edited by way_up_north; 07-07-2020, 02:21 PM.

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          • #7
            I used blue painters masking tape because I was hoping it wouldn't pull off the plastic film on the windscreen. The adhesive on the painters tape isn't that strong. It did allow me to adjust the individual strips without pulling off too much of the plastic, but when I pulled the fairing off, the plastic protective stuff also came off. I will tape some heavy paper over it for protection so I don't scratch it up.

            Comment


            • svyolo
              svyolo commented
              Editing a comment
              I use Mark's technique occasionally, but I didn't do it this time. Thinking about it, it would have been entirely appropriate, and I would probably do that if I was going to do it again. If you are doing this in hot weather, you will appreciate Mark's tip. 15 or 20 degrees makes a huge difference in how fast epoxy or polyester go off.

          • #8
            I preferer grinding on fiberglass all in one go but it started raining. I got the windshield fairing pretty close to final outline. I usually us an angle grinder with a 36 or 40 grit disc. Anything finer usually loads up pretty fast. I have a 6 X 48 belt sander and I mostly used that with a 60 grit belt. Tyvek suit, respirator, and googles. About an hours work, including grinding down the vertical fin fairings.
            Last edited by svyolo; 07-11-2020, 08:45 PM.

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            • #9
              I did my best to try to measure where I wanted the online to be, but ended up just eyeball engineering probably a third of it. I cut it proud of the line, and ground the glass down to the line with the belt sander. The belt sander made quick work of it and did a good job getting the curves fair. In a perfect world, the left and right would be a perfect mirror image. In reality, the two will never be viewed simultaneously, so having them look good individually is more important than the two looking identical.

              The fitment issue I had was it was a battle between fitting the windshield to the wing leading edge, and not having enough clearance on the cowl. In the end the leading edge of the wing sets proud of the windscreen leading edge by a little under 1/2", and the middle of the fairing will have to be recessed in the center so the engine cowl sheetmetal will have to sit under it by a similar amount.

              The last couple of pics are one side of the vertical fin fairing, if I decide to use it.

              Comment


              • Mark Goldberg
                Mark Goldberg commented
                Editing a comment
                The windshield lower fairing looks good John. Mark

            • #10
              Thanks a lot for the writeup and the pictures.
              Nice job.

              Comment


              • #11
                Can you share who your supplier is and what cloth products you used? How many layers did you apply to the rear fairing and the windshield fairing?
                Brooks Cone
                Southeast Michigan
                Patrol #303, Kit build

                Comment


                • #12
                  Windshield fairing I used 4" glass tape from ACS and some scrap carbon fiber, only because I had the CF. I wouldn't have bought it for this. I used 6 layers of glass and 3 of CF. If I was using only glass, I would have used 10 layers. My 8 layers are .135" thick. The tape was barely wide enough at the door post, but it was enough. Less tightly woven fabric would require more layers.

                  Epoxy I used Aeropoxy from ACS. I was low on System 3 and thought I would try it. I like it, but West System or System 3 are available locally and just as good in most respects. If you can get epoxy locally, it will save on shipping. You buy epoxy by the quart or gallon. A quart of resin plus hardener plus the hardener is enough. Buying by the gallon is cheaper if you are going to use it for other things. West and System 3 sell pumps that fit their bottles. It is much easier to dispense. Without that, you need to either measure volume or weight.

                  The tail fairing I used 3 layers of glass, and 2 of CF. If I was doing it again I would use mostly CF. 1 Layer of glass at the bottom, that touches the airframe. I think it is strong enough.

                  I have bought fiberglass from lots of sources over the years, and CF from only a few. The stuff ACS sells is as good or better than any I have used before. Very tight weave. Their prices are very competitive.

                  Comment


                  • #13
                    The glass tape I used is listed as 8.7 oz/sq yard which is a little heavier than most cloth at 5 or 6 oz. If you use lighter cloth you will need more layers.

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                    • #14
                      This company has great pricing on carbon fiber: https://www.sollercomposites.com/Carbon-3K-Fabrics.html
                      Rob Caldwell
                      Davidson, North Carolina
                      EAA Chapter 309
                      BH Model B Quick Build Kit Serial # 11B-24B / 25B
                      Build Log: https://bearhawk4place.blogspot.com/
                      YouTube Channel: http://bearhawklife.video

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                      • #15
                        Since I have to look at this piece all the time I would like it to look good. With the glass and epoxy and the strange shape it is tough to be able to tell how fair it came out with my eyeballs. I just put some epoxy mixed with wood flour (micro balloons for most folks, I just happen to have the wood flour) to fill the glass weave, and I will put a cheap coat of gray or white primer on it to see how fair the shape is before I start to finish it.

                        Mix the micro and epoxy to a consistency to thinpeanut butter, or a little thinner. I slapped it on with a cheap brush and smoothed it with a plastic scraper. It is very light, and easy to sand.

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