Apr 21, 2024     form blocks and aluminum layout - (4 hours)       Category: Wings

I haven't been updating the log as much as planned, but I'm still getting some time each day on the Bearhawk.

Over the past few weeks, I have completed all the cutting templates, and most of the forming templates. One of the issues that took some extra time was fulling in areas on the forms where I had found nicks. I'm probably being over cautious, but I'd rather keep trying to get as close to perfection as I can and not simply accept stuff as okay if I can make it better.

I am debating whether I should deviate slightly from the normal process and build individual forming blocks for the various sections of the wings. In Eric Newton's construction manual, he advocates making a single form from the full sized template. I see the logic- every part is from the same forming block and guaranteed to match size wise and you spend a whole lot less time creating forms. Then you're going to spend time fluting, and getting all flanges to 90 degrees.

The option I'm considering is to make the separate form blocks, and shape each section with a 6-10 angle back and carve the flutes into the form. The result should be less time getting everything in shape since the extra angle will allow for spring back and the flutes are always going to be in the same place. Theoretically, it should mean only minor tweaking with each produced part.

I am also looking at how to create my flanging dies. I've got a few ideas, but so far haven't settled on one specific way.

The other area I've spent a bit of time on recently is getting ready for my first aluminum order. I am hoping to source everything locally, and have contacted the local Metal Supermarket. They can get me the 2024-t3 sheets in either 4x8 or 4x12 sheets. I played around with some potential cutting plans trying to minimize waste and get all the parts. On Monday, I'll call and get prices and I can compare which will be the least expensive way to obtain the material. I should be able to start bending aluminum in early May.

  Mar 04, 2024     Cutting Forms - (2.0 hours)       Category: Wings

Working on the Bearhawk has been a bit challenging due to family issues, but I finally managed to squeeze in a few hours to make the cutting forms.

The first thing I did was to wait for my order from Aircraft Spruce of 3ft of 1/4x .028 tubing. I cut this into 1/2" sections to be used as bushings. this proved to be a bit more challenging than anticipated. I tried it first using the bandsaw, which worked fine until the blade dulled out. I tried a few variations using my Dremel rotary tool. I found I got the best results when I clamped the tubing in the vise, held onto the end with a pair of pliers and then cut.

On the wing template, I enlarged each tooling hole to 1/4", used a 1/2" spade bit to countersink the outer edge and then used a hammer to tap the bushings into place. With these set, I clamped a plank to the template, drilled at least 2 holes and used a 3/16 (10x24) machine screw and wing nut to secure everything in place.

I left the clamps on and used a stack of washers that had a 9/16' outer thickness and traced around the template to give me a line to cut and sand to final shape. I repeated the process with the other templates.

  Jan 07, 2024     Master Wing Template, Aileron Template, Flap Template - (8.5 hours)       Category: Wings

Beginning on New Year's day, I started by using plan sheet 4, the full size wing template on mylar and attached it to a reclaimed piece of oak. I then placed a second piece behind it and tacked with a few small nails before carefully cutting the assembly out on the band saw. I made the first cut to about 1/4" from the line and then made a second cut to about 1/16".

I spent about 2 hours using drawings 9 & 10 to make accurate copies of the templates for the ailerons, flaps and aileron pocket ribs and the associated cutting templates. The next day I took them out to the shop, glued them onto pieces of oak. For the forming templates, I again doubled the stack. I predrilled the jig fixture holes and any area where the material would have a corner. Using the band saw, I again cut these to 1/16" beyond the line.

I ended up spending some time doing a bit of research on how to create a jig for my belt sander. I needed to put together a way I could ensure the sanding edge would be perpendicular to the face of the template. I found with a bit of shimming and a couple of clamps, I could get the belt sander to do what I needed. Using this set up, I was able to sand all of the templates to the line and finish this step.

  Jan 01, 2024     Why a Bearhawk 5 - (1.0 hour) Category: Research

Why did someone who has no tailwheel experience and no plans to do back country flying decide to build a Bearhawk Model 5 from scratch?
It is said that the decision of airplane (whether to build or buy) is always a series of compromises. My journey is no different. When I thought about my mission, it is mostly going to be local and mid length (200 NM) cross country flights with a few 500+ NM trips per year. The cross country trips will be with my spouse and my 50+ pound service dog, so I automatically want something with at least 4 seats and baggage capability. I will almost exclusively be going from paved airport to paved airport, so a tri gear would be the preference. I want a decent cruise speed, and my spouse wants high wings.

At this point, the almost perfect airplane would be a Cessna 182. However, I don't like the prices of purchase or ongoing maintenance with certificated planes. Besides, one of my personal goals is to earn my A&P. I have thought of buying a fuselage with a data plate from a scrapyard and doing a complete rebuild, but I think the need for the certificated parts would make the project cost prohibitive.

So the question I had to answer was how to fulfill most of our mission. I excluded any 2 place planes (a dog who is the size of a young child needs her own seat). There aren't a ton of options left at this point. Van's RV-10 is nice, but it has low wings and the price of the kits is staggering. The RV is going to land at 60 -70 kts. Sling's Highwing plane looks nice, but from what I've been able to ascertain, it's even more expensive than the RV and the kits are still pretty new. I don't want to be a first builder. And to be honest, I like the idea of building from scratch. Let's just call it my version of arts and crafts.

The Bearhawk line has been around since the early 90's with the four place model. The line has several models that have been added over the years, but they all share common elements: tube and fabric fuselage, all metal wings with a Riblett airfoil. They carry a good load at reasonable speeds. Doing some research on the Bearhawk yeilded a video with Budd Davisson talking about the Bearhawk kits. In the video, he says the Bearhawk isn't a bush plane, it's a real honest plane that just happens to land and take off short. He continues with saying the Bearhawk can be anything you want it to be.

Well, that's what I'm going to try for. My Bearhawk is going to be a traveling machine with more emphasis on comfort than on creating a STOL machine. The Model 5 has roughly the same interior space of the 182, but I can build it from scratch, so I think it's the best compromise. The biggest hurdle is I'll need to get a tailwheel endorsement.