Source: 2006 Q2 Beartracks, Russ Erb
Those of you who have been working for several years on your Bearhawk may be encouraged or discouraged by this little fact. 26 February 2006 marked the 10th Anniversary of mailing the check to “The Bob” to purchase plans set #164. Building would go much faster if life didn’t keep getting in the way.
My F1 Rocket buddy had been asking lately “So, when do we get to start calling you Betsy Ross?” Shortly after the 10th anniversary I started applying fabric to the fuselage. In keeping with guidance in a former Bear-Tracks, I started by covering the inside of the fuselage first. This is by far more difficult than covering the outside
because of all of the many tubes and appurtenances that must be worked around. You also need to be very aware of which way the fabric wraps around the tube or you could find yourself having insufficient room to wrap the outside fabric around the tubes.
Note that I put the fabric on the outside of the diagonal tube that the front seat attaches to. I did this because my seat design would otherwise penetrate the side fabric when slid to the rear position. Also note that because of the 1/4” tube supporting the door sill, the fabric is attached to the diagonal seat tube in two pieces with a cement seam over the tube. A finishing tape was applied over this seam before the outer fabric was applied.
Also of note are the open areas in the wing roots which will have windows to see the fuel sight gauges. I chose to put my sight gauges on the wing roots instead of in the cabin so that the fuel will stay outside if a leak should develop. Also note that the ceiling fabric runs to the top of the airfoil and not straight across as in the
prototypes. This allows me to see the entire sight gauge instead of just the bottom half. Two longitudinal tubes were added to the “X” across the top of the cabin to help form the fabric for this transition.
The left side wall fabric behind the main door and the vaulted ceiling over the rear seat/cargo area were rib laced to the fuselage tubes to hold the concave shape. The large hole in the front ceiling is for access to the trim system and dome light. The other two holes in the ceiling are for additional dome lights. The rear fuel lines are attached to the door posts simply by fabric wrapped around the door post.
I chose to use the original rounded windows for the rear seat. Attaching the fabric to the window channels was challenging to say the least. Basically the Poly-Tak was stuffed in the channel with a brush and the fabric was pushed into it with a putty knife. The interior fabric was cut to go down inside one side of the channel. The exterior fabric went down inside one side and back up the other, forming a fabric to fabric bond. This picture also shows the finishing tape applied around the round edge with no wrinkles or cuts. This was a bias tape stretched on the outer edges instead of the center like seen around the outside of curved edges. To get the fabric to really lie down inside the channel, I needed an iron that would fit in the channel to stick the fabric down with heat as described in the Poly Fiber manual. The solution was to use a piece of 1/8” aluminum clamped to my small hobby iron.



The dirty little secret of covering the fuselage is that you have to do some sewing somewhere in order to make the transition from the fuselage to the vertical fin. You can do it by hand or by machine, using the appropriate Poly Fiber thread. While the Poly Fiber manual and video imply that you need a heavy duty sewing machine to sew the fabric, that’s not really the case. I used my wife’s home sewing machine with no problems. I sewed a seam from the lower fin leading edge to the upper stringers and then a seam up each stringer. Pat Fagan managed to get away with one seam up the left stringer because of the particular geometry of the cargo door. I didn’t hear about that until after I had done both seams. The method I used would work with or without the cargo door. The picture shows me in the process of sewing the fuselage envelope (top and sides, belly was a separate piece) which I came to refer to as my “Bearhawk Wedding Dress”.
After cementing to the fuselage and heat shrinking, the seams looked like this at the base of the vertical fin before finishing tapes were applied. You can also see a slight bulge from the balsa ribs added as suggested by Peter Stevens. These ribs support the fabric so that it is not pulled way in out of shape by the rib lacing. After applying the first coat of Poly Brush, the fuselage is turned to a very manly shade of pink. You can see the initial application of custom inspection rings for the horizontal stabilizer attachments, later covered with more fabric. Also shown is the rib lacing on the vertical fin ribs.



So when will #164 fly? That’s the classic question for all homebuilders. The classic answer is “We plan to fly before Christmas.” Just don’t ask him which year he’s talking about. My biggest concern is that I’m starting to wonder if Eric Newton is going to fly his Bearhawk out to see me before I can fly mine out to see him!