Hog Bipe – Top Wing Construction

Made some progress over the weekend on the Hog Bipe. The top wing is close to being completed. So far, building everything stock and according to plans.

20140518_212136539_iOS 20140518_212147235_iOS

No major issues so far and only one minor issue. The kit only comes with a single piece of 1/6″ x 3″ x 48′ sheeting to be used to sheet the front portion of the top wing. The piece was badly bowed such that I needed to trim it down to just a bit over 2-3/4″ to get a straight and true edges front and back. Fortunately, this was just enough to give me a good glue joint to the top spar.

The top sheeting was also a bit tricky to glue down properly. I started at the left edge and glued the front of the sheeting to the leading edger, one bay at a time, using medium CA and kicker. Once the front of the sheeting was attached, I wet it down with Windex to soften and help it to curve, and then using a toothpick spread TightBond wood glue on top of the ribs and along the spar. I like using wood glue rather than CA for attaching the sheeting to the ribs, especially considering the number of ribs involved in this long wing panel, as it has a longer work time and allows you to fuss and adjust a bit.

I then start at one end and press the sheeting down into the glue on the rib and on then the spar, pinning it as I go. I work one bay at a time and am careful not to let the sheeting buckle as I go. After removing the wing from the building board, I added a fillet of wood glue between the ribs, the spar, the leading edger and the sheeting on the inside.

 20140524_182014680_iOS

After letting the glue dry thoroughly, I pulled the wing off the board and after adding the maple mounting blocks, added the bottom sheeting. I used a slightly different technique this time. Here, I preformed the curved shape by wetting with Windex and gently bending the sheeting around the rounded corner of my workbench. It is not critical that the shape of the sheeting be perfect, just reasonably close.

I then applied wood glue to all ribs, the inside of the leading edge and spar and then dropped the preformed sheeting onto the glue. I then pinned the sheeting to the leading edge, and worked the sheeting back by pressing to the rib and spar just like top sheeting. On one side, I worked the leading edge to spar one bay at a time. Although this worked well, I ended up with a slight gap (about 1/32″) between the front of the sheeting and the leading edge on the last two bays on the outboard edge. I ended up filling it in with a bit scrap. On the other side, I pinned the sheeting to the leading edge first, then went back to pin down to the ribs and spar. This worked much better.

20140526_214330230_iOS

That’s all for now.

SSE – Just About Done

My SSE project is just about done. All I have left to do is final assembly of the main landing gear and final installation of the electronics (receiver, EEC, BEC). I also need to order a set of batteries so I can do a final balance.

I polished up the main gear bracket and clear coated it yesterday. I was unhappy with the look of the clear coat though, as the polished aluminum seemed to lose much of its luster under it. The only reason for the clear coat was to protect the shine, so I stripped it off with a bit of acetone and buffed the aluminum back out again. This time, I put on a simple coat of carnauba wax to protect the aluminum finish.

I also painted the wheel pants white. I was happy with how they came out, until I came back to check on them and found a hair settled into the paint on one. I will see how it looks after the paint fully dries, but I am likely to do a little light sanding and add one more coat of paint to both before final assembly.

I have not been out flying yet this season and I want to get some stick time on some of my old standby birds before trying a maiden on the SSE, so for now, I will move onto my next build.

New Build – Hog Bipe

With my SSE project nearing completion, I cleared off some bench space and kicked off my next build, a Sig Hog Bipe. I will build it as a “fantasy scale” early Army Air Corps plane with the blue fuselage and yellow wings color scheme. I am also thinking about some sort of custom cowl instead of the traditional Sig style open nose.

20140504_210159458_iOS

Of course I am planning an electric conversion. Sig calls for 6.5 – 7.5 lb all up weight and a 0.60 sized glow motor. For electric motor sizing, I’ll round up to an even 8 lbs and plan on 150 watts per lb, which will put me right at 1200 watts. I want to keep with 6S batteries (22.2v), which will then need to draw about 54 amps.

I like to have the motor on had when I start the build, so I can use the motor mount as a template to drill mounting holes in the firewall before assembling the firewall into the fuselage. I am leaning towards a Cobra C-4130-12 motor. Their site includes a prop chart which lists about 1120 watts with a 13×6.5 prop and just a tick under 1200 watts with a 13×8. The 13×8 prop (drawing 54 amps), is just a bit over the 52 amp continuous limit for this motor, so as long as I am not flying max throttle all the time, I should be in a safe zone.

Battery capacity may be an issue though. I am hoping to use the same batteries here as my SSE. For the SSE, I want to keep to 4000 mAh maximum in order to keep to a reasonable weight. But 4000 mAh may not give me enough flying time for a heavier plane drawing higher current. As always, there are trade-offs with electric set ups, and I need to digest on this a bit before I make my final selection.

Since I have not finalized motor selection, I will get started on the wing panels now. Given my slow build rate, by the time I am done there, I will have settled on a motor and have it in hand. I will be back traveling again this week, so I won’t even be able to start until the week after, though.